ANATOMY
DESCRIPTIVE AND SURGICAL
BY
HENRY (GRAY, F.B.S.
1 1, '— '
FELLOW OF THK ROYAL COLLEGE OF SURGEONS; LECTURER OX ANATOMY AT ST. GEORGE 8
HOSPITAL MEDICAL SCHOOL, LONDON
SEVENTEENTH EDITION
THOROUGHLY REVISED AND RE-EDITED WITH ADDIT1OXS
BY
JOHN CHALMERS DACOSTA, M.I).
PROFESSOR OF T«K PRINCIPLKS OF SURGERY AND OF CLINICAL SURGERY IN THE JEFFERSON MEDICAL COI.I.1.CK
PHILADELPHIA
EDWARD ANTHONY SPITZKA, M.D.
PROFESSOR OF GENERAL ANATOMY IN THE JEFFERSON MEDICAL COLLEGE, PHILADELPHIA
Illustrate*) witb 1149 Engravings
LEA & FEBIGER
PHILADELPHIA AND NEW YORK
1908
Entered according to the Act of Congress, in the year 1908, by
LEA & FEBIGER,
in the Office of the Librarian of Congress. All rights reserved.
THIS
NEW AMERICAN EDITION OF GRAY'S ANATOMY
IS DEDICATED TO
WILLIAM W. KEEN, M.D, LL.D, HON. F.KC.S. [ENG. AND EDIN.]
THE DISTINGUISHED PROFESSOR OF SURGERY IN JEFFERSON
MEDICAL COLLEGE
AS AN EVIDENCE OF
THE ADMIRATION, THE AFFECTION AND THE GRATITUDE OF HIS COLLEAGUE
AND FORMER ASSISTANT
THE EDITOR
EDITORS' PREFACE.
THE fact that this new edition has been demanded so soon after the publication
of the sixteenth edition is gratifying evidence of the continued popularity and
usefulness of "Gray."
In this edition there have been many alterations, a number of eliminations, and
additions of important anatomical facts. One hundred and thirty-three new
illustrations have been inserted and thirty-eight old ones have been improved
and re-engraved, and it is hoped and believed that the cuts will warrant more
than ever the approbation of students and teachers. In the illustrations of the
Nerve System special effort has been bestowed on combining the features visible
to the naked eye with those seen only under high magnifying powers. By the
knowledge of macroscopic and microscopic structures the attentive student is
enabled to resolve or reconstruct, in the three dimensions of space, and with his
mental eye see the opaque interior resolved into intricate yet well-defined pro-
jecting and associating mechanisms. Such study is assisted by new illustrations
depicting hidden structures in accordance with this principle. Much that could
not be described in detail within the confines of a text-book has been summarized
in such way as to be of assistance even to advanced students.
Histology and embryology have been treated by resumes, as heretofore. Free
quotations have been made from numerous treatises, monographs, and reports,
the invariable intention being to give proper credit to the authors.
A universally accepted international nomenclature of anatomical items is
eminently desirable. A transition from the old to the new will of necessity be
gradual, because in the minds of many the older names are not only fixed but
also cherished. The Latin or international nomenclature is in many respects a
distinct advance in accuracy and simplicity. It has gained many advocates, but
has not as yet completely displaced older designations to the degree its enthu-
siastic advocates would wish. In this edition the custom previously adopted is
still pursued, and the names, according to the new nomenclature, have been
introduced in parentheses, following those still in current use in English-speaking
countries.
The section on the Nerve System, which has been largely rewritten by Dr.
Spitzka, has been prepared with due regard to the advances recently made in the
morphological and embryological aspects of the subject. The more important
physiological and pathological data have been presented in their anatomical
bearings, in order to demonstrate with greater clearness the mutual relations of
the structure and functions of the nerve system.
The Digestive System, the Ductless Glands, and the Female Organs of Gener-
ation have also received careful consideration by the editors, and they trust these
portions of the book will be found to merit the approval of students and teachers.
The editors wish to thank Mr. William A. Hassett, of Lea & Febiger, for
indexing the book, for seeing it through the press, and for the valuable aid he
has ungrudgingly given.
JOHN CHALMERS DA COSTA,
EDWARD ANTHONY SPITZKA.
(v)
PUBLISHERS' NOTE TO SEVENTEENTH EDITION.
A NEW edition of Grays Anatomy is always an event of importance to the
English-speaking world of medicine. For fifty years it has been easily the leading
work in all medical literature, broadly considered, and, a fortiori, preeminent in its
own field, a position which the many excellent treatises that have appeared from
time to time have only rendered more conspicuous. During its first half-century
it has given hundreds of thousands of students their foundation in medicine, and
has been the one book carried from college for guidance in the basic questions
underlying the practice of medicine and surgery. Its value for reference leads to a
large absorption of each new edition on the part of practitioners desiring to be
posted on the most recent developments and bearings of anatomy. This double
demand brings about three important results for its readers: In the first place,
rendering possible frequent new editions, whereby Gray may always be consulted
for the latest knowledge; secondly, warranting an otherwise impossible expense
for revisions and improvements; and thirdly, combining these advantages with a
low price. A glance at the intrinsic causes which have led to these conditions may
not be amiss.
Henry Gray's genius was twofold. He united a profound understanding of
human structure with equal insight into the best methods of imparting knowledge
to other minds. Reflecting this unique combination of powers, his Anatomy
sprang to the front and has never lost its precedence. It joins a text of inimitable
didactic quality with engravings of equal force and clearness. If Gray had dis-
cerned nothing else than the great advantage to his readers of having the names of
the various parts engraved directly on the body of an illustration, he would have
performed a notable service. His work, still unique in this respect, was also the
first to employ colors. It is hardly to be wondered at that students and teachers
alike find their labors cut in half and the permanence of knowledge doubled by
the use of such a book.
The early death of Henry Gray has enlisted in successive revisions of this
work the services of many leading anatomists. Passing over the intervening
editions, and bearing in mind the close relations between anatomy and surgery,
it is scarcely necessary to allude to the advantage of uniting in this new issue the
knowledge of so eminent a surgeon as Dr. Da Costa, and of Dr. Spitzka, equally
eminent as a specialist in anatomy. Professor Spitzka also possesses the ability
(vii)
viii PUBLISHERS' NOTE
of a skilful artist, and his delineations therefore convey his grasp of structure
directly to the eye of the reader.
As ample directions are given for dissecting, this single volume will serve everv
requirement of the student throughout his course. The new nomenclature and
that still in common use have been introduced in a manner rendering the work
universal in the prime essential of terminology. The Table of Contents is so
arranged as to give a complete conspectus of anatomy, a feature of obvious
value. The whole book is thoroughly organized in its headings and the sequence
•of subjects, so that the student receives his knowledge of the parts in their
anatomical dependence.
As a teaching instrument the new Gray's Anatomy embodies all that careful
thought and unstinted expenditure can combine in book form, and it now enters
its second half-century well equipped to excel even its own record.
CONTENTS.
DESCRIPTIVE AND SURGICAL ' ANATOMY,
OSTEOLOGY— THE SKELETON.
PAGE
The Skeleton 33
Number of the Bones 33
Form of Bones 33
Long Bones 33
Short Bones 33
Flat Bones 34
Irregular Bones 34
Surfaces of Bones 34
Structure of Bone 34
Bloodvessels of Bone 39
Chemical Composition of Bone .... 41
Ossification and Growth of Bone ... 42
THE VERTEBRAL OR SPINAL COLUMN.
General Characters of a Vertebra.
The Cervical Vertebrae
Atlas
Axis
Seventh Cervical
The Thoracic or Dorsal Vertebra? .
Peculiar Dorsal Vertebrae ....
The Lumbar Vertebra?
Structure of the Vertebrae
Development of the Vertebrae ....
Development of the Atlas
Development of the Axis
Development of the Seventh Cervical .
Development of the Lumbar Vertebrae
Progress of Ossification in the Spine Gener-
ally
The Sacral and Coccygeal Vertebra;
Sacrum
Differences in the Sacrum of the
Male and Female ....
Peculiarities of the Sacrum
Coccyx
The Vertebral Column or Spine in General .
Surface Form of the Vertebral Column .
Surgical Anatomy of the Vertebral Column
THE SKULL.
The Cerebral Cranium.
The Occipital Bone
The Parietal Bone
The Frontal Bone
Vertical Portion of the Frontal Bone .
Horizontal or Orbital Portion of the
Frontal Bone
The Temporal Bone
Squamous Portion of the Temporal
Bone
The Mastoid Portion of the Temporal
Bone
The Petrous Portion of the Temporal
Bone
49
50
52
53
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55
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PAGE
The Sphenoid Bone 92
The Body of the Sphenoid Bone . . 92
The Greater or Temporal Wings of the
Sphenoid Bone 95
The Lesser or Orbital Wings of the
Sphenoid Bone 96
The Pterygoid Processes of the Sphe-
noid Bone 96
The Sphenoidal Spongy Bone ... 97
The Ethmoid Bone 98
The Horizontal Lamina or Cribriform
Plate of the Ethmoid Bone . . .99
The Vertical or Perpendicular Lamina
or Plate of the Ethmoid Bone . . 100
The Lateral Mass or Labyrinth of the
Ethmoid Bone 100
Development of the Cranium .... 102
The Fontanelles 102
Supernumerary or W'ormian Bones . 103
Congenital Fissures and Gaps . . . 104
Bones of the Face.
The Nasal Bones . 104
The Superior Maxillary Bones .... 105
The Body of the Superior Maxilla . . 105
The Processes of the Superior Maxillae 109
Malar Process of the Superior Max-
illa 109
Nasal Process of the Superior Max-
illa 109
Alveolar Process of the Superior
Maxilla 109
Palate Process of the Superior
Maxilla 110
Changes Produced in the Upper Jaw by Age 112
The Lachrymal Bone 112
The Malar Bone 113
The Palate Bone 115
The Horizontal Plate of the Palate
Bone 116
The Vertical or Perpendicular Plate of
the Palate Bone 117
The Inferior Turbinated Bone . . . 119
The Vomer 120
The Maxillary Bone, Inferior Maxilla, Man-
dible or Lower Jaw 122
The Horizontal Portion or Body of the
Mandible 122
The Perpendicular Portion or Kami of
the Mandible 124
Changes Produced in the Lower Jaw by
Age '.125
The Sutures 127
The Skull as a Whole.
The Vertex of the Skull
88 ; The Base of the Skull
129
130
(ix)
CONTENTS
PAGE
The Lateral Region of the Skull ... 136
The Temporal Fossa 137
The Mastoid Portion 138
The Zygomatic or Infra temporal Fossa 138
The Spheno-maxillary or Pterygo-pala-
tine Fossa 139
The Anterior Region of the Skull ... 139
Orbits, Orbital Cavities or Orbital Fossae 140
The Nasal Cavity 142
Shape of the Skull ' 146
Dimensions of the Skull 147
Surface Form of the Skull 148
Fixed Points for Measurement of the Skull 150
Surgical Anatomy of the Skull .... 150
The Hyoid or Lingual Bone 155
THE THCRAX.
The Sternum 1 57
The Ribs 161
Common Characters of the Ribs . . 161
Peculiar Ribs 163
The Costal Cartilages 165
Surface Form of the Chest 166
Surgical Anatomy of the Chest .... 167
THE UPPER EXTREMITY.
The Shoulder Girdle.
The Clavicle 169
Surface Form of the Clavicle . . . 172
Surgical Anatomy of the Clavicle . . 172
The Scapula 172
Surface Form of the Scapula . . . 178
Surgical Anatomy of the Scapula . . 178
The Arm.
The Humerus .7 179
Surface Form of the Humerus . . . 185
Surgical Anatomy of the Humerus . 185
The Forearm.
The Ulna '. . 186
Surface Form of the Ulna . . . .191
The Radius 192
Surface Form of the Radius . . . 194
Surgical Anatomy of the Radius and
Ulna 194
The Hand.
The Carpus 195
Common Characters of the Carpal Bones 195
Bones of the Upper Row .... 197
Scaphoid or Navicular Bone . . 197
Semilunar Bone 198
Cuneiform Bone 199
Pisiform Bone 199
Bones of the Lower Row .... 200
Trapezium 200
Trapezoid 200
Os Magnum 201
Unciform 201
PAGE
The Metacarpus 202
Common Characters of the Metacarpal
Bones 202
Peculiar Characters of the Metacarpal
Bones 203
The Phalanges of the Hand 206
Surface Form of the Bones of the Hand 206
Surgical Anatomy of the Bones of the Hand 207
Development of the Bones of the Hand . 207
THE LOWER EXTREMITY.
The Pelvic Girdle.
The Pelvis 209
The False Pelvis 209
The True Pelvis 209
Position of the Pelvis 211
Axes of the Pelvis 211
Differences Between the Male and the
Female Pelvis 212
The Os Innominatum 213
The Ilium 215
The Ischium 217
The Pubis 219
The Cotyloid Cavity or Acetabulum . 220
The Obturator or Thyroid Foramen . 220
Surface Form of the Pelvis .... 222
Surgical Anatomy of the Pelvis . . 222
The Thigh.
The Femur or Thigh Bone 223
Surface Form af the Femur . . .231
Surgical Anatomy of the Femur . . 232
The Leg.
The Patella or Knee-cap 233
Surface Form of the Patella . . . 234
Surgical Anatomy of the Patella . . 234
The Tibia or Shin Bone 234
Surface Form of the Tibia .... 239
The Fibula or Calf Bone 239
Surface Form of the Fibula . . . 241
Surgical Anatomy of Bones of the Leg 244
The Foot.
The Tarsus 244
The Calcaneus or Heel Bone . . . 244
The Astragalus or Ankle Bone . . . 246
The Cuboid 248
Scaphoid or Navicular Bone . . . 249
Cuneiform or Wedge Bones .... 249
The Metatarsal Bones 252
Common Characters of Metatarsal Bones 252
Peculiar Characters of Metatarsal Bones 252
The Phalanges of the Foot 255
Development of the Foot 255
Construction of the Foot as a Whole . 256
Surface Form of the Foot .... 258
Surgical Anatomy of the Foot .... 258
Sesamoid Bones 259
THE ARTICULATIONS OR JOINTS.
Structures Composing the Joints . . . 261
Bone 261
Cartilage 261
Ligaments 263
Synovial Membranes 264
Forms of Articulation:
Synarthrosis 266
Amphiarthrosis . 266
Diarthrosis 267
The "Kinds of Movement Admitted in
Joints 268
Ligamentous Action of Muscles .... 270
ARTICULATIONS OF THE TRUNK.
Articulations of the Vertebral Column .
Articulations of the Atlas with the Axis . 276
Articulations of the Spine with the Cranium.
Articulation of the Atlas with the Occipital
Bone
Articulation of the Axis with the Occipital
Bone . 280
Surgical Anatomy of Articulations of the
Spine ......... 281
CONTENTS
XI
Articulation of the Lower Jaw or the Tem-
poro-mandibiilar Articulation . . 282
Surface Form 284
Surgical Anatomy 284
Articulations of the Ribs with the Vertebrae
or the Costo-vertebral Articulations . . 285
Articulation of the Cartilages of the Ribs
with the Sternum, etc., or the Costo-
stornal Articulations 289
Articulations of the Cartilages of the
Ribs with Each Other or the Inter-
chondral Articulations .... 291
Articulations of the Ribs with their Car-
tilages or the Costo-chondral Artic-
ulations 292
Articulations of the Sternum .... 292
Articulations of the Vertebral Column with
tlio Pelvis 292
Articulations of the Pelvis 294
Articulation of the Sacrum and Ilium . 294
Ligaments passing between the Sacrum
and Ischium 294
Articulation of the Sacrum and Coccyx 296
Articulation of the Ossa Pubis . . . 298
ARTICULATIONS OF THE UPPER EXTREMITY.
Sterno-clavicular Articulation .... 299
Surface Form 301
Surgical Anatomy 301
Acromio-clavicular Articulation or Scapulo-
clavicular Articulation .... 301
Surface Form 303
Surgical Anatomy 303
Proper Ligaments of the Scapula . . . 303
The Shoulder-joint 305
Surface Form of the Shoulder-joint . 309
Surgical Anatomy of the Shoulder-
joint 309
The Elbow-joint 310
Surface Form of the Elbow-joint . . 314
Surgical Anatomy of the Elbow-joint . 314
Radio-ulnar Articulation 315
Superior or Proximal Radio-ulnar Artic-
ulation 316
Surface Form 316
Surgical Anatomy 316
Middle Radio-ulnar Ligaments . . . 316
Inferior or Distal Radio-ulnar Artic-
ulation 317
Surface Form 319
Radio-carpal or Wrist-joint 319
Surface Form of wrist-joint . . . 320
Surgical Anatomy of Wrist-joint . . 320
Articulations of the Carpus 321
Articulations of the First Row of Carpal
Bones 321
Articulations of the Second Row of Car-
pal Bones 321
Articulations of the Two Rows of Car-
pal Bones 322
PAGE
Carpo-metacarpal Articulations .... 323
Articulation of the Metacarpal Bone of
the Thumb with the Trapezium . 323
Articulations of the Metacarpal Bones of
the Four Inner Fingers with the Carpus 324
Articulations of the Metacarpal Bones
with Each Other . .... 326
Metacarpo-phalangeal Articulations . . 326
Surface Form of Metacarpo-phalangeal
Articulations 327
Articulations of the Phalanges .... 327
ARTICULATIONS OF THE LOWER EXTREMITY.
The Hip-joint 327
Surface Form of the Hip-joint . . . 335
Surgical Anatomy of the Hip-joint . 335
The Knee-joint 336
Surface Form of the Knee-joint . . 345
Surgical Anatomy of the Knee-joint . 345
Tibio-fibular Articulation 347
Superior Tibio-fibular Articulation . 347
Middle Tibio-fibular Ligament or Inter-
osseous Membrane . ... 348
Inferior Tibio-fibular Articulation . . 348
The Tibi-o-tarsal Articulation or Ankle-joint 349
Surface Form of Ankle-joint . . . 353
Surgical Anatomy of Ankle-joint . . 353
Articulations of the Tarsus 354
Articulation of the Os Calcis and As-
tragalus or the Calcaneo-astragaloid
Articulation 354
Articulation of the Os Calcis with the
Cuboid or the Calcaneo-cuboid Artic-
ulation 355
The Ligaments connecting the Os Calcis
and Scaphoid or the Calcaneo-
scaphoid Articulation Ligaments 355
Surgical Anatomy 356
Articulation of the Astragalus with the
Scaphoid Bone or the Astragalo-
scaphoid Articulation .... 356
The Articulation of the Scaphoid with
the Cuneiform Bones 357
The Articulation of the Scaphoid with
the Cuboid 357
The Articulations of the Cuneiform
Bones with Each Other or the Inter-
cuneiform Articulations .... 357
The Articulation of the External Cunei-
form Bone with the Cuboid . 358
Surgical Anatomy 358
Tarso-metatarsal Articulations .... 359
Articulations of the Metatarsal Bones with
Each Other 360
The Sy no vial Membranes in the Tarsal
and Metatarsal Joints 360
Metatarso-phalangeal Articulations . . 361
Articulations of the Phalanges .... 361
Surface Form 362
Surgical Anatomy 362
THE MUSCLES AND FASCLE.
General Description of Muscles .... 363
General Description of Tendons . . . 366
General Description of Aponeuroses . . 366
General Description of Fasciae .... 366
MUSCLES AND FASCIAE OF THE CRANIUM AND
FACE.
Subdivision into Groups 368
The Cranial Region 368
Dissection 368
Superficial Fascia 368
Surgical Anatomy 369
The Occipito-frontalis 369
Surgical Anatomy 371
The Auricular Region 371
Dissection 371
Attrahens Auriculam or Aurem . . 372,
Attollens Auriculam or Aurem. . . 372
Retrahens Auriculam or Aurem . . 372
The Palpebral Region 372
Dissection 372
Orbicularis Palpebrarum .... 372
Corrugator Supercilii 373
Levator Palpebrse 373
Tensor Tarsi or Horner's Muscle . . 373
The Orbital Region 374
Levator Palpebra Superioris . . . 375
Superior Rectus 375
Inferior Rectus 375
Xll
CONTENTS
PAGE
The Orbital Region —
External Rectus 375
Superior Oblique
Inferior Oblique ..'.....
Fasciae of the Orbit 377
Surgical Anatomy 377
The Nasal Region 373
Pyramidalis Nasi 37g
Levator Labii Superiorly Alaeque Nasi 378
Dilator Naris Posterior ..... 378
Dilator Naris Anterior 378
Compressor Nasi 378
Compressor Narium Minor .... 378
Depressor Alse Nasi 378
The Superior Maxillary Region .... 379
Levator Labii Superions .... 379
Levator Anguli Oris 379
Zygomaticus Major 379
Zygomaticus Minor 379
The Mandibular Region 380
Dissection 380
Levator .Labii Inferioris or Levator
Menti 380
Depressor Labii Inferioris or Quadratus
Menti 380
Depressor Anguli Oris or Triangularis
Menti 380
The Intermaxillary Region ..... 381
Dissection 381
Orbicularis Oris 381
Buccinator 382
Risorius or Santorini's Muscle . . . 383
The Temporo-mandibular Region . . . 383
Masseteric Fascia 383
Masseter Muscle 383
Temporal Fascia 384
Dissection 384
Temporal Muscle 384
The Pterygo-mandibular Region . . . 385
Dissection 385
External Pterygoid Muscle .... 386
Internal Pterygoid Muscle .... 386
Surface Form of Muscles of Head and Face 387
MUSCLES AND FASCI.E OF THE NECK.
Subdivision in Groups 387
The Superficial Cervical Region .... 388
Dissection 388
Superficial Cervical Fascia .... 388
Platysma Myoides 388
Deep Cervical Fascia 389
Surgical Anatomy 391
Sterno-mastoid orSterno-cleido-mastoid 391
Surface Form 393
Surgical Anatomy .'.... 393
The Infra-hyoid Region 393
Dissection 393
Sterno-hyoid 394
Sterno-thyroid 394
Thyro-hyoid 395
Omo-hyoid 395
The Supra-hyoid Region 396
Dissection 396
Digastric 396
Stylo-hyoid 396
Mylo-hyoid 397
Dissection 397
Genio-hyoid 397
The Lingual Region 398
Dissection 399
Genio-hyo-glossus 399
Hyo-glossus 399
Chondro-glossus 399
Stylo-glossus 399
Palato-glossus or Constrictor Isthmi
Faucium 400
Muscular Substance of the Tongue . 400
Surgical Anatomy 402
The Pharyngeal Region
Dissection . . . .t
Inferior Constrictor . .
Middle Constrictor ....
Superior Constrictor ....
Stylo-pharyngeus ....
The Palatal Region
Dissection ....
Levator Palati
Circumflexus or Tensor Palati
Palatine Aponeurosis
Azygos Uvulae
Palato-glossus or Constrictor Isthmi
Faucium
Palato-pharyngeus
Salpingo-pharyngeus ....
Surgical Anatomy
The Anterior Vertebral Region ....
Rectus Capitis Anticus Major or Lorigus
Capitis
Rectus Capitis Anticus Minor .
Rectus Capitis Lateralis ....
Longus Colli
The Lateral Vertebral Region ....
Scalenus Anticus
Scalenus Medius .
Scalenus Post ic us
Surface Form of Muscles of the Neck
MUSCLES AND FASCIAE OF THE TRUNK.
Subdivision into Groups
Muscles of the Back.
Subdivision into Groups
The First Layer
Dissection
Superficial Fascia
Deep Fascia
Trapezius
Ligamentum Nuchae
Latissimus Dorsi
The Second Layer
Dissection
Levator Anguli Scapulas
Rhomboideus Minor
Rhomboideus Major
The Third Layer
Dissection
Serratus Posticus Superior ....
Serratus Posticus Inferior ....
Vertebral Aponeurosis
Lumbar Fascia or Aponeurosis
Splenius
Splenius Capitis
Splenius Colli
The Fourth Layer . !
Dissection . .
Erector Spinae
Ilio-costalis or Sacro-lumbalis .
Musculus Accessorius ad Ilio-cos-
talem
Cervicalis Ascendens ....
Longissimus Dorsi
Transversalis Cervicis or Trans-
versalis Colli
Trachelo-mastoid
Spinalis Dorsi
Spinalis Colli
Complexus
The Fifth Layer .
Dissection
Semispinalis Dorsi
Semispinalis Colli
Multifidus Spinae ....
Rotatores Spinae
Supraspinales
Interspinales
Extensor Coccygis
Intertransversales . ...
Rectus Capitis Posticus Major .
PAGE
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CONTEXTS
Xlll
The Fifth Layer —
Rectus Capitis Posticus Minor . . . 424
Obliquus Capitis Inferior .... 424
Obliquus Capitis Superior .... 424
Surface Form of Muscles of the Back . . 426
Muscles and Fascice oj the Thorax.
Intercostal Fascia 426
Intercostal Muscles 427
External Intercostals 427
Internal Intercostals 427
Infracostales 427
Triangularis Sterni 427
Levatores Costarum 428
Diaphragm 429
Ligamentum Arcuatum Internum . . 429
Ligamentum Arcuatum Externum . 429
Central Tendon of the Diaphragm . . 431
The Openings of the Diaphragm . . 431
Muscles of Inspiration and Expiration 434
Muscles of the Abdomen,
The Superficial Muscles of the Abdomen . 434
Dissection 434
Superficial Fascia 435
Deep Fascia 435
External or Descending Oblique . . 435
Aponeurosis of External Oblique . 436
External Abdominal Ring . . . 437
External Pillar or Inferior Crus . 438
Internal Pillar or Superior Crus . 438
Intercolumnar Fibres .... 438
Poupart's Ligament .... 438
Gimbernat's Ligament . . . 439
Triangular Fascia or Colles's Liga-
ment 439
Ligament of Cooper .... 439
Suspensory Ligament of the Penis 439
Suspensory Ligament of the Clitoris 439
Internal or Ascending Oblique . . . 439
Aponeurosis of Internal Oblique . 441
Cremaster Muscle 441
Transversalis 444
Dissection 444
Rectus Abdominis 444
Pyramidalis 446
The Linea Alba 446
The Lineae Semilunares . . . 447
The Lineae Transversse .... 447
The Transversalis Fascia .... 447
Internal or Deep Abdominal Ring . 448
The Inguinal or Spermatic Canal . . 450
The Deep Crural Arch 450
Cooper's Ligament 450
Surface Forms of Muscles of the Abdomen 450
The Deep Muscles of the Abdomen . . 451
The Fascia Covering the Quadratus
Lumborum 451
Quadratus Lumborum 451
Muscles of the Pelvic Outlet.
The Muscles of the Ischio-rectal Region . 451
The Corrugator Cutis Ani .... 451
External Sphincter Ani 452
Internal Sphincter Ani 453
Levator Ani 453
Pubococcygeus Muscle .... 454
Iliococcygeus Muscle .... 456
foccygeus 457
The Muscles and Fascia? of the Perinaeum in
the Male 457
Superficial Fascia 457
The Central Tendinous Point of the
Perinaeum 458
Transversus Perinei Superficialis . . 459
Accelerator LTrina? 459
Erector Penis 460
Triangular Ligament .... 460
Compressor or Constrictor LTrethrae . 462
PAGE
The Muscles of the Perinn-um in the Female 462
Transversus Perinei Superficialis . . 462
Sphincter Vaginae 463
Erector Clitoridis 463
Triangular Ligament .... 464
Compressor Urethras 4(14
MUSCLES AND FASCI.K OF THE UPPER
EXTREMITY.
Subdivision into Groups 464
Dissection of Pectoral Region and Axilla . 465
The Muscles and Fasciae of the Thoracic '
Region.
The Anterior Thoracic Region .... 465
Superficial Fascia 465
Deep Fascia 465
Pectoralis Major 466
Dissection 469
Costo-coracoid Membrane or Clavipec-
toral Fascia 469
Pectoralis Minor 470
Subclavius 470
The Lateral Thoracic Region . . . .471
Serratus Magnus 471
Surgical Anatomy 471
Dissection 471
Muscles and Fascia? oj Shoulder and
Superficial Fascia
Deep Fascia ' . . • .
The Acromial Region
Deep Fascia
Deltoid
Surgical Anatomy .
The Anterior Scapular Region .
Dissection
The Subscapular Fascia ....
Subscapularis
The Posterior Scapular Region .
Dissection
Supraspinatus Fascia ....
Supraspinatus Muscle . ...
Infraspmatus Fascia ....
Infraspinatus Muscle ....
Teres Minor
Teres Major
The Muscles and Fascice of the Arm.
The Anterior Humeral Region .
Dissection
Deep Fascia
Coraco-brachialis
Biceps or Biceps Flexor Cubiti .
Brachialis Anticus
The Posterior Humeral Region .
Triceps or Triceps Extensor Cubiti
Subanconeus
Surgical Anatomy
Muscles and Fascice of the Form r in.
Dissection .
Deep Fascia
The Anterior Radio-ulnar Region .
The Superficial Layer
Pronator Radii Teres .
Surgical Anatomy .
Flexor Carpi Radialis .
Palmaris Longus ....
Flexor Carpi Ulnaris
Flexor Sublimis Digit orum
The Deep Layer
Dissection
Flexor Profundus Digitorum .
Flexor Longus Pollicis .
Pronator Quadratus ...
Surgical Anatomy
\rm.
472
472
472
472
472
473
473
473
473
473
474
474
474
474
474
474
475
475
476
476
476
477
477
478
479
479
480
480
480
480
481
481
481
481
481
482
482
483
484
484
484
484
485
486
XIV
CONTENTS
PAGE
The Radial Region 486
Dissection 486
Supinator Longus 486
Extensor Carpi Radialis Longior . . 487
Extensor Carpi Radialis Brevior . . 487
The Posterior Radio-ulnar Region . . . 488
The Superficial Layer 48S
Extensor Communis Digitorum . 488
Extensor Minimi Digiti . . . 489
Extensor Carpi Ulnaris . . . 489
Anconeus 489
The Deep Layer 489
Supinator Radii Brevis . . . 489
Extensor Ossis Metacarpi Pollicis 491
Extensor Brevis Pollicis . . . 491
Extensor Longus Pollicis . . . 491
Extensor Indicis 492
Surgical Anatomy 493
Muscles and Fasciae of the Hand.
Dissection 493
Ligamentum Carpi Volare 493
Anterior Annular Ligament 493
The Synovial Membranes of the Flexor Ten-
dons at the Wrist 494
Surgical Anatomy 494
Burssc about the Hand and Wrist . . . 494
Posterior Annular Ligament 495
The Deep Palmar Fascia 495
The Superficial Transverse Ligament of
the Fingers 496
Surgical Anatomy 496
The Radial Region 497
Abductor Pollicis 497
Opponens Pollicis 498
Flexor Brevis Pollicis 499
Adductor Obliquus Pollicis .... 499
Adductor Transversus Pollicis . . . 499
The Ulnar Region ........ 500
Palmaris Brevis 500
Abductor Minimi Digiti 500
Flexor Brevis Minimi Digiti ... . 500
Opponens Minimi Digiti .... 500
The Middle Palmar Region 501
Lumbricales 501
Interossei 501
Surface Form of Muscles of the Upper Ex-
tremity ... 502
Surgical Anatomy of Muscles of the Upper
Extremity 505
MUSCLES AND FASCIAE OF THE LOWER
EXTREMITY.
Subdivision into Groups 509
Muscles and Fasciae of the Iliac Region.
Dissection 510
Iliac Fascia 510
Psoas Magnus 512
Psoas Parvus 512
Iliacus 512
Surgical Anatomy 513
Muscles and Fasciae of the Thigh.
The Anterior Femoral Region .
Dissection
Superficial Fascia
Deep Fascia or Fascia Lata
Surgical Anatomy ....
Tensor Fascia? Femoris ....
Sartorius
Quadriceps Extensor ....
Rectus Femoris
Vastus Externus
Vastus Internus ....
Crureus
Subcrureus
Surgical Anatomy
514
514
514
515
517
517
518
518
518
520
520
520
521
521
The Internal Femoral Region .
Dissection
Gracilis
Pectineus
Adductor Longus ....
Adductor Brevis
Adductor Magnus
Hunter's Canal
Surgical Anatomy
The Muscles and Fasciae of the Hip
The Gluteal Region
Dissection
Gluteus Maximus
Gluteus Medius
Gluteus Minimus
Pyriformis
Obturator Internus
Gemelli
Gemellus Superior ....
Gemellus Inferior ....
Quadratus Femoris . . . .
Obturator Externus
Surgical Anatomy
The Posterior Femoral Region .
Dissection
Biceps or Biceps Flexor Cruris .
Semitendinosus
Semimembranosus
Surgical Anatomy
PAGE
522
522
522
522
522
523
523
524
525
525
525
525
526
526
527
528
529
529
530
530
531
531
532
532
532
533
533
534
Muscles and Fasciae of the Leg.
The Anterior Tibio-fibular Region . . . 534
Dissection 535
Deep Fascia of the Leg . . ' . . . 535
Tibialis Anticus 535
Extensor Proprius Hallucis . . . 535
Extensor Longus Digitorum . . . 536
Peroneus Tertius 537
The Posterior Tibio-fibular Region . . . 537
Dissection 537
The Superficial Layer 537
Gastrocnemius 537
Soleus 538
Tendo-Achillis 538
Plantaris 539
The Deep Layer 540
Deep Transverse Fascia . . . 540
Popliteus . 540
Flexor Longus Hallucis . . .541
Flexor Longus Digitorum . . . 541
Tibialis Posticus 541
The Fibular Region 542
Dissection 542
Peroneus Longus 542
Peroneus Brevis 543
Surgical Anatomy of Tendons around Ankle 544
Muscles and Fasciae of the Foot.
Dissection 544
Anterior Annular Ligament 544
Internal Annular Ligament 545
External Annular Ligament 545
Dissection of the Sole of the Foot . . . 545
Plantar Fascia .... ... 545
Central Portion of Plantar Fascia . . 545
Lateral Portions of Plantar Fascia . 546
Bursa? about the Ankle and Foot . . . 546
Surgical Anatomy 546
The Dorsal Region . . . . . . . 546
Fascia 546
Extensor Brevis Digitorum .... 54*3
The Plantar Region 547
The First Layer 547
Dissection 547
Abductor Hallucis 547
Flexor Brevis Digitorum . . . 547
Fibrous Sheaths of the Flexor
Tendons 548
Abductor Minimi Digiti . . . 548
CONTENTS
xv
The Plantar Region —
Tin- Second Layer ...... 549
Flexor Accessorius . . . . . 549
Lumbricales 549
The Third Layer 549
Flexor Brevis Hallucis .... 549
Adductor Obliquus Hallucis . . 549
Flexor Brevis Minimi Digiti . . 550
Adductor Transversus Hallucis . 551
The Plantar Region —
The Fourth Layer 551
Interossei Muscles 551
Dorsal Interossei . . . .551
Plantar Interossei . • . . 551
Surface Form of Muscles of the Lower Ex-
tremity 552
Surgical Anatomy of Muscles of the Lower
Extremity 554
THE BLOOD-VASCULAR SYSTEM.
The Circulation of the Blood .... 557
The Cavity of the Thorax .... 558
The Upper Opening of the Thorax . . . 558
The Lower Opening of the Thorax . . . 558
THE PERICARDIUM.
Structure of the Pericardium .... 560
Fibrous Layer 560
Serous Pericardium 562
Arteries of the Pericardium .... 563
Nerves of the Pericardium .... 563
The Vestigial Fold of the Pericardium 563
Surgical Anatomy of the Pericardium . . 563
THE HEART.
Position of the Heart 564
Size and Weight of the Heart .... 566
Capacity of the Cavities of the Heart . . 566
Fat upon the Heart 566
Component Parts of the Heart .... 567
Right Forechamber or Auricle . . . 567
Left Forechamber or Auricle . . . 570
Right Ventricle 571
Left Ventricle 573
Structure of the Heart . . ... 576
Endocardium 576
Myocardium 576
Muscular Structure of the Heart . . 577
The Auriculo-ventricular Fasciculus or
Bundle of His 579
Vessels and Nerves of the Heart . . . 580
Surface Form of the Heart 580
Surgical Anatomy of the Heart .... 580
Peculiarities of Vascular System in Fostus. 581
The Foramen Ovale 581
The Eustachian Valve 581
The Ductus Arteriosus 582
The Umbilical Arteries 583
Fretal Circulation 583
Changes in the Vascular System at Birth . 584
THE ARTERIES.
Distribution of the Arteries 77.". . 585
Anastomosis of the Arteries 585
Histology of the Capillaries and Arteries . 586
Blood-vessels of the Blood-vessel Wall . 588
Lymphatics of Arteries 588
Nerves of Arteries 588
Arterial Sheath 588
PULMONARY ARTERY.
Right Pulmonary Artery 589
Left Pulmonary Artery 589
THE AORTA.
The Ascending Aorta.
Relations of the Ascending Aorta . . .591
Branches of the Ascending Aorta . . . 592
The Coronary Arteries 592
Right Coronary Artery 592
Left Coronary Artery 593
Peculiarities of Coronary Arteries . . 593
The Arch of the Aorta.
Relations of the Arch of the Aorta . . . 594
Peculiarities of the Arch of the Aorta . . 594
Surgical Anatomy of the Arch of the Aorta 594
Branches of the Arch of the Aorta . . . 595
Peculiarities of the Branches . . . 595
The Innominate Artery 596
Relations 596
Branches 596
Thyroidea Ima 596
Peculiarities 597
Surgical Anatomy 697
ARTERIES OF -THE HEAD AND NECK.
The Common Carotid Artery.
Relations of the Common Carotid Artery . 600
Peculiarities of the Common Carotid Artery 601
Surface Marking of the Common Carotid
Artery
Surgical Anatomy of the Common Carotid
Artery
The External Carotid Artery ....
Relations
Surface Marking
Surgical Anatomy
Branches
Superior Thyroid Artery .
Branches
Surgical Anatomy ....
Lingual Artery
Relations
Branches
Surgical Anatomy ....
Facial or External Maxillary Artery
Relations
Branches
Peculiarities
Surgical Anatomy ....
Occipital Artery
Branches
Posterior Auricular Artery
Branches
Ascending Pharyngeal Artery
Branches
Surgical Anatomy ....
Superficial Temporal Artery .
Surgical Anatomy .... 613
Internal Maxillary Artery . . . 613
Branches of First Portion . 615
Surgical Anatomy . . 615
Branches of Second Portion . 616
Branches of Third Portion . 616
Surgical Anatomy . . 617
Surgical Anatomy of the Triangles of the
Neck . 618
Anterior Triangle of the Neck . . . 618
Posterior Triangle of the Neck . . . 620
XVI
CONTENTS
PAGE
The Internal Carotid Artery ..... 620
Cervical Portion 621
Relations 622
Petrous Portion 622
Cavernous Portion 622
Cerebral Portion 623
Peculiarities 623
Surgical Anatomy 623
Branches 623
Tympanic 623
Arterise Receptaculi .... 623
Predural or Anterior Meningeal . 623
Ophthalmic 624
Branches 624
Precerebral or Anterior Cerebral . 628
Branches 628
Medicerebral or Middle Cerebral . 629
Branches 629
Postcommunicant or Posterior
Communicating 630
Prechoroid or Anterior Choroid . 630
The Bloodvessels of the Brain.
The Central Ganglionic System .... 632
The Cortical Arterial System .... 632
ARTERIES OF THE UPPER EXTREMITY.
The Subclavian Artery.
First Part of the Right Subclavian Artery . 633
Relations 633
First Part of the Left Subclavian Artery . 635
Relations 635
Second and Third Parts of Subclavian Artery 635
Relations 635
Third Portion of the Subclavian Artery . 636
Peculiarities of the Subclavian Artery . . 636
Surface Marking of the Subclavian Artery . 637
Surgical Anatomy of the Subclavian Artery 637
Branches of the Subclavian Artery . . . 639
Vertebral Artery 639
Relations 639
Branches 640
Surgical Anatomy 641
Basilar Artery 641
Branches 641
Circulus or Circle of Willis . . . 642
Thyroid Axis 642
Branches 643
Internal Mammary Artery .... 645
Relations 646
Branches 646
Surgical Anatomy 647
Superior Intercostal Artery .... 647
Deep Cervical Branch .... 647
Surgical Anatomy of the Axilla .... 647
Boundaries 647
Contents 648
Surgical Anatomy 648
The Axillary Artery.
Relations of the Axillary Artery 7 . . 650
Peculiarities of the Axillary Artery . . 651
Surface Marking of the Axillary Artery ' . 651
Surgical Anatomy of the Axillary Artery . 651
Branches of the Axillary Artery . . . 652
Superior Thoracic Artery .... 652
Acromial Thoracic Artery or Thoracic
Axis 653
Branches 653
Long Thoracic or External Mammary
Artery 653
Alar Thoracic Artery 653
Subscapular Artery 653
Circumflex Arteries 653
The Brachial Artery.
Relations of the Brachial Artery . . . 654
Surgical Anatomy of the Bend of the Elbow 655
Peculiarities of the Brachial Artery . . 655
Surface Marking of the Brachial Artery . 656
Surgical Anatomy of the Brachial Artery . 656
Branches of the Brachial Artery
Superior Profunda Artery .
Nutrient Artery ....
Inferior Profunda Artery .
Anastomotica Magna
Muscular Branches .
PAGE
. : 657
. . 657
. . 658
. . 658
. . 658
. . 658
The Anastomosis around the Elbow-joint 659
The Radial Artery 659
Relations 659
The Deep Palmar Arch ... 660
Peculiarities 660
Surface Marking 660
Surgical Anatomy 660
Branches 661
Radial Recurrent 661
Muscular Branches 661
Anterior Radial Carpal . . .661
Superficialis Volae 661
Posterior Radial Carpal . . . 661
Dorsalis Pollicis 661
Dorsalis Indicis 661
Princeps Pollicis 662
Radialis Indicis 662
Perforating Arteries .... 662
Palmar Interosseous .... 6G2
Palmar Recurrent Branches . . 662
The Ulnar Artery '. . 662
Relations 663
Peculiarities 663
Surface Marking 663
Surgical Anatomy . . . . . . 663
Branches . 664
Anterior Ulnar Recurrent . . . 664
Posterior Ulnar Recurrent . . 664
Interosseous Artery .... 664
Muscular Branches 665
Anterior Carpal 665
Posterior Carpal 665
Deep Palmar Arch 666
Superficial Palmar Arch . . . 666
Relations 666
Branches 666
Surface Marking .... 667
Surgical Anatomy .... 667
ARTERIES OF THE TRUNK.
The Descending Aorta.
The Thoracic Aorta 667
Relations 667
Surface Marking 668
Surgical Anatomy 668
Branches 668
Bronchial Arteries 668
(Esophageal Arteries .... 668
Pericardiac Arteries .... 668
Posterior Mediastinal Arteries . 668
Intercostal Arteries and Branches 669
Surgical Anatomy .... 670
The Abdominal Aorta 670
Relations 671
Surface Marking 672
Surgical Anatomy 672
Branches 673
The Creliac Axis or Artery . . 673
Relations 673
Branches 673
Surgical Anatomy .... 676
The Superior Mesenteric Artery . 677
Branches .... . 677
Blood-supply of the Right Iliac
Fossa 678
The Inferior Mesenteric Artery . 679
Suprarenal Artery 680
The Renal Arteries 680
The Spermatic Arteries . . . 681
The Ovarian Arteries . . . .681
The Inferior Phrenic Arteries . . 682
The Lumbar Arteries .... 682
Branches .... 682
CONTENTS
xvn
The Common Iliac Arteries.
Branches of Common Iliac Arteries . . 683
Peculiarities of Common Iliac Arteries. . 684
Surface Marking of Common Iliac Arteries 684
Surgical Anatomy of Common Iliac Arteries 684
The Internal Iliac Artery 685
Relations 685
Peculiarities 686
Surgical Anatomy 687
Branches 687
Superior Vesical Artery . . . 687
Middle Vesical Artery .... 688
Inferior Vesical Artery .... 688
Middle Hsemorrhoidal Artery . 688
Uterine Artery 688
Vaginal Artery 688
Surgical Anatomy .... 689
Obturator Artery 689
Branches 689
Peculiarities . . . . . 690
Internal Pudic Artery .... 690
Relations 691
Peculiarities 691
Surgical Anatomy . . . .691
Branches 691
Sciatic Artery 603
Branches 694
Lateral Sacral Artery .... 694
Branches 694
Gluteal Artery 695
Branches 695
Surface Marking 695
Surgical Anatomy .... 695
The External Iliac Artery 695
Relations 695
Surface Marking 696
Surgical Anatomy 696
Branches 697
Internal or Deep Epigastric Artery 697
Branches . . • . . . . 697
Peculiarities 697
Surgical Anatomy .... 698
Deep Circumflex Iliac Artery . . 698
ARTERIES OF THE LOWER EXTREMITY.
The Femoral Artery.
Scarpa's Triangle 698
Hunter's Canal or the Adductor Canal . 699
The Common Femoral Artery .... 700
Relations 701
The Superficial Femoral Artery .... 701
Relations 701
Peculiarities 702
Surface Marking 702
Surgical Anatomy 702
Branches 704
Superficial Epigastric .... 704
Superficial Circumflex Iliac . . 704
Superficial External Pudic . . 704
Deep External Pudic .... 704
Deep Femoral or Prof unda Femoris 704
Relations 705
Branches .... 705
The Superficial Femoral Artery —
Muscular Branches 706
Anastomotica Magna .... 706
Branches 706
The Popliteal Artery.
The Popliteal Space 707
Dissection 707
Boundaries 707
Position of Contained Parts . . . 708
Peculiarities 708
Surface Marking 709
Surgical Anatomy 709
Branches 709
Superior Muscular Branches . . 709
Inferior Muscular Branches . . 709
Cutaneous Branches . . . .710
Superior Articular Arteries . . 710
Azygos Articular Artery . . .710
Inferior Articular Arteries . . . 71Q
Circumpatellar Anastomosis . . 710
The Anterior Tibial Artery 710
Relations 71 1
Peculiarities 71 1
Surface Marking 711
Surgical Anatomy 7n
Branches 712
Posterior Recurrent Tibial . . 712
Superior Fibular 712
Anterior Recurrent Tibial . . . 713
Muscular Branches 713
Malleolar Arteries 713
The Dorsalis Pedis Artery 713
Relations 713
Peculiarities 713
Surface Marking 714
Surgical Anatomy 714
Branches 714
Cutaneous Branches .... 714
Tarsal Artery 714
Metatarsal Artery 715
Communicating Artery . . .715
The Posterior Tibial Artery 715
Relations 715
Peculiarities 716
Surface Marking 716
Surgical Anatomy 716
Branches 716
Peroneal Artery 717
Relations 717
Peculiarities '." . . .717
Branches 717
Cutaneous Branches .... 718
Nutrient Artery 718
Muscular Branches 718
Communicating Branch . . . 718
Malleolar or Internal Malleolar
Artery 718
Internal Calcanean Arteries . .718
Internal Plantar Artery . . .718
External Plantar Artery . . . 719
Surface Marking . . . .719
Surgical Anatomy .... 719
Branches 719
THE VEINS.
Subdivisions of the Veins
Anastomosis of Veins
Histology of the Veins ....
The Superficial or Cutaneous Veins .
The Deep Veins
THE PULMONARY VEINS.
THE SYSTEMIC VEINS.
Veins of the Head and Neck.
Veins of the Exterior of the Head and Face
721
722
722
723
723
725
Veins of the Exterior of the Head and Face —
Frontal Vein 725
Supraorbital Vein . .* . . . . 726
Angular Vein 726
Anterior Facial Vein 726
Common Facial Vein 726
Superficial Temporal Vein .... 727
The Pterygoid Plexus and the Internal
Maxillary Vein 727
Temporo-maxillary Vein .... 727
Posterior Auricular Vein .... 727
Occipital Vein 727
CONTENTS
PAGE
The Veins of the Neck . . . . . . 728
External Jugular Vein 728
Posterior External Jugular Vein . . 728
Anterior Jugular Vein 728
Internal Jugular Vein . . . . . 729
Lingual Veins 729
Pharyngeal Veins 730
Superior Thyroid Vein .... 730
Middle Thyroid Vein .... 730
Veins of the Thyroid Gland . . 73-1
Surgical Anatomy 732
Vertebral Vein 732
Anterior Vertebral or Anterior
Deep Cewical Vein .... 733
Posterior Vertebral or Posterior
Deep Cervical Vein .... 733
The Veins of the Diploe 733
The Dural or the Meningeal Veins . . 734
The Cerebral Veins 734
Superficial or Cortical Cerebral Veins . 735
Supercerebral or Superior Cerebral
Veins 735
Medicerebral or Median Cerebral Veins 735
Subcerebral or Inferior Cerebral Veins . 735
Velar, Deep Cerebral, Central or Ven-
tricular Veins, Veins of Galen . 735
Vena Corporis Striati |. . . . 735
Choroid Vein '..'.... 735
Basilar Vein ....... 735
Superficial Cerebellar Veins . . . 736
Deep Cerebellar Veins 736
Veins of the Pons 736
Veins of the Oblongata .... 736
The Sinuses of the Dura, Ophthalmic Veins
and Emissary Veins 736
Longitutinal or Superior Longitudinal
Sinus 736
Torcular Herophili 737
Falcial or Inferior Longitudinal Sinus . 738
Tentorial or Straight Sinus .... 738
Lateral Sinus 738
Surgical Anatomy 739
Occipital Sinus 739
Cavernous Sinus 739
Surgical Anatomy 740
Sphenoparietal Sinus or Sinus Alae Parvae 740
Ophthalmic Veins 740
Circular Sinus 742
Superpetrosal or Superior Petrosal Sinus 742
Subpetrosal or Inferior Petrosal Sinus 742
Transverse or Basilar Sinus .... 743
Emissary Veins 743
Surgical Anatomy 743
Veins of the Upper Extremity and Thorax.
The Superficial Veins of Upper Extremity . 745
Superficial Veins of the Hand and Fin-
gers 745
Anterior Ulnar Vein 745
Posterior or Dorsal Ulnar Vein . . 745
Common Ulnar Vein 745
Radial Vein 745
Median Vein 745
Median Cephalic Vein 746
Median Basilic Vein .... 746
Basilic Vein 746
Cephalic Vein 747
The Deep Veins of the Upper Extremity . 747
Interosseous Veins 747
Deep Palmar Veins 747
Brachial Veins 747
Axillary Vein ......... 747
Branches 748
Surgical Anatomy 748
Subclavian Vein 749
Innominate or Brachio-cephalic Veins 750
Right Innominate Vein 750
Left Innominate Vein • 750
Peculiarities 750
The Deep Veins of the Upper Extremity —
Internal Mammary Vein
Inferior Thyroid Veins .
Intercostal Veins
Precava or Superior Vena Cava
Relations
Azygos Veins
Surgical Anatomy .
Bronchial Veins
The Spinal Veins
Dorsi-spinal Veins
Meningo-rachidian Veins
Veins of the Bodies of the Vertebra or
Venae Basis Vertebrarum ....
Veins of the Spinal Cord or Medulli-
spinal Veins
Veins of the Lower Extremity, Abdomen
and Pelvis.
The Superficial Veins of the Lower Extrem-
ity
The Superficial Veins of the Foot .
Internal or Long Saphenous Vein
External or Short Saphenous Vein
Surgical Anatomy
The Deep Veins of the Lower Extremity
The Deep Veins of the Foot
Posterior Tibial Veins
Anterior Tibial Veins
Popliteal Vein
Femoral Vein
External Iliac Vein
Deep Epigastric Vein
Deep Circumflex Iliac Vein
Hypogastric or Internal Iliac Vein
Surgical Anatomy
Obturator Vein
Sciatic Veins
Gluteal Veins . . . . ' .
Superior Vesical Plexus ....
Prostatic or Prostatico-vesical Plexus .
Inferior Vesical Plexus
Surgical Anatomy
The Dorsal Veins of the Penis .
The Vaginal Plexuses and Veins .
The Uterine Plexuses and Veins
Common Iliac Vein
Peculiarities
Postcava, Ascending or Inferior Vena
Cava
Relations
Peculiarities
Lumbar Veins
Spermatic Veins
Ovarian Veins
Renal Veins
Suprarenal Veins
Phrenic Veins
Hepatic Veins :
THE PORTAL SYSTEM OF VEINS.
Superior Mesenteric Vein
Splenic Vein . . . .
Inferior Mesenteric Vein ,
Gastric Veins . . . .
Cystic Vein .
Portal Vein
The Cardiac Veins.
Great Cardiac or Left Coronary Vein
Posterior or Middle Cardiac Vein
Left Cardiac Vein
Anterior Cardiac Vein ....
Right Cardiac or Small Coronary Vein
Coronary Sinus
Vena? Thebesii
PAGE
750
751
752
752
752
752
753
753
753
753
754
755
755
756
756
756
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757
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758
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759
760
761
761
761
761
761
761
762
762
762
763
763
764
764
764
764
764
765
765
766
767
767
767
767
768
768
768
768
769
769
770
771
771
771
771
771
771
CONTENTS
xix
THE LYMPHATIC SYSTEM.
Subdivision into Superficial and Deep Sets 773
Lymphatic or Conglobate Glands . . . 774
Hemolymph nodes 774
Surgical Anatomy 775
THE THORACIC DUCT AND THE RIGHT
LYMPHATIC DUCT.
Radicals of Origin and Tributaries of Tho-
racic Duct 776
Structure of the Thoracic Duct .... 777
The Right Lymphatic Duct 777
Tributaries 778
LYMPHATICS OF THE CRANIAL REGION, FACE
AND NECK.
The Lymphatic Glands of the Head and Face 778
The Occipital or Suboccipital Glands . 779
The Posterior Auricular, Retro-auricu-
lar or Mastoid Glands .... 779
Parotid Lymph Glands 779
The Subparotid Glands . ... 781
The Internal Maxillary or Zygomatic
Glands . 781
The Facial Glands or Genial Glands . 781
The Lymphatic Vessels of the Cranial Region 781
The Lymphatic Vessels of the Face, the In-
terior of the Nose, Tongue, Floor of the
Mouth, Pharynx, Larynx and Thyroid
Gland 782
The Lymphatic Glands of the Neck . . 783
The Superficial Cervical Glands . . 783
The Submaxillary or Lateral Supra-
hyoid Glands 784
The Submental or Median Suprahyoid
Glands 784
The Retro-pharyngeal or Post-pharyn-
geal Glands 784
The Deep Cervical, Carotid, or Sterno-
mastoid Glands 785
The Lymphatic Vessels of the Neck . . 786
Surgical Anatomy 786
THE LYMPHATICS OF THE UPPER EXTREMITY.
The Lymphatic Glands of the Upper Ex-
tremity 787
The Superficial Lymphatic Glands . 787
The Deep Lymphatic or the Axillary
Glands 787
The Lymphatic Vessels of the Upper Ex-
tremity 790
The Superficial Lymphatic Vessels of
the Upper Extremity 790
The Deep Lymphatic Vessels of the
Upper Extremity .... 790
Surgical Anatomy 791
THE LYMPHATICS OF THE LOWER EXTREMITY.
The Lymphatic Glands of the Lower Ex-
tremity 791
The Superficial Inguinal Lymphatic
Glands 791
Surgical Anatomy 794
The Deep Lymphatic Glands of the
Lower Extremity . . . 794
The Deep Inguinal or Deep Fem-
oral Lymphatic Glands . . . 794
The Anterior Tibial Gland . . 794
The Popliteal Glands .... 794
The Gluteal and Ischiatic Glands 794
The Lymphatic Vessels of the Lower Ex-
tremity 794
The Superficial Lymphatic Vessels of
the Lower Extremity 795
The Deep Lymphatic Vessels of the
Lower Extremity 795
THE LYMPHATICS OF THE PELVIS AND
ABDOMEN.
The Iliac or Ilio-pelvic Glands .... 795
The External Iliac Glands .... 795
The Internal Iliac or Hypogastric Glands 796
The Common Iliac Gland .... 796
The Abdomino-aortic Glands .... 797
The Right Juxta-aortic Glands . . 797
The Left Juxta-aortic Glands . . . 798
The Retro-aortic Glands .... 798
The Pre-aortic Glands 798
The Glands along the Mesenteric
Arteries 798
The Glands connected with the
Cosliac Axis and its Branches . 798
The Gastric Glands 793
The Splenic Glands 798
The Hepatic Glands .... 798
The Lymphatic Vessels of the Abdomen and
Pelvis 799
The Superficial Lymphatic Vessels of
the Walls of the Abdomen . . 799
The Superficial Lymphatic Vessels
of the Gluteal Region . . . 799
The Superficial Lymphatic Vessels
of the Scrotum and Perinaeum . 799
The Superficial Lymphatic Vessels
of the Penis 799
The Deep Lymphatic Vessels of the
Abdominal Wall ... . 799
The Lymphatic Vessels of the Um-
bilicus 799
The Lymphatic Vessels of the Peri-
toneum 800
The Lymphatic Vessels of the
Bladder 800
The Lymphatic Vessels of the Pros-
tate Gland 800
The Lymphatic Vessels of the Male
Urethra 801
The Lymphatic Vessels of the Fe-
male Urethra 801
The Lymphatic Vessels of the
Uterus . 801
The Lymphatic Vessels of the Fal-
lopian Tube 801
The Lymphatic Vessels of the
Ovary 801
The Lymphatic Vessels of the
Vagina 802
The Lymphatic Vessels of the
Testicle 802
The Lymphatic Vessels of the
Vas Deferens 802
The Lymphatic Vessels of the
Seminal Vesicles 802
The Lymphatic Vessels of the
Kidney, Ureter, and Suprarenal
Capsule 802
The Lymphatic Vessels of the Liver 802
The Lymphatic Vessels of the
Bile-ducts 803
The Lymphatic Vessels of the
Stomach 804
The Lymphatic Vessels of the
Pancreas 804
The Lymphatic Vessels of the
Spleen 804
THE LYMPHATIC SYSTEM OF THE INTESTINES.
The Lymphatic Glands of the Small Intestine 805
The Lymphatic Vessels of the Small Intestine 806
The Lymphatic Glands of the Large Intestine 806
The Colic Glands 806
The Rectal Glands . 806
XX
CONTENTS
The Lymphatic Vessels of the Large Intestine
Lymphatics of the Anus and Rectum
THE LYMPHATICS OF THE THORAX.
PAGE
806
807
The Lymphatic Glands of the Thoracic Wall
or the Parietal Lymphatics . . . 807
The Internal Mammary Glands . . 807
The Intercostal Glands 808
The Diaphragmatic Lymphatics . . 808
The Visceral Lymphatics .... 808
The Anterior Mediastinal 'Glands . 808
The Posterior Mediastinal Glands . 808
The Peritracheo-bronchial Glands 809
PAGE
The Lymphatic Vessels of the Thoracic Wall 810
The Cutaneous Lymphatics .... 810
Lymphatics of the Mammary Gland . 810
Lymphatics of the Great Pectoral
Muscle 811
Surgical Anatomy 811
The Pulmonary Lymphatics . . . 812
The Pleural Lymphatics . . . 812
The Cardiac Lymphatics .... 812
The Thymic Lymphatic Vessels . . 813
The Lymphatic Vessels of the (Esoph-
agus 813
The Lymphatic Vessels of the Thoracic
Trachea 813
THE NERVE SYSTEM.
THE SPINAL CORD AND BRAIN WITH THEIR
MENINGES.
Fundamental Facts regarding the Devel-
opment of the Nerve System .... 816
Development of Nerve Tissue ..... 818
In the Wall of the Neural Tube . . . 818
In the Neural-crest Tissue .... 819
Structure of the Nerve System .... 819
The Neurone ........ 820
Nerve-cell Body ...... 820
Unipolar cells ..... 820
Bipolar cells ...... 820
Multipolar cells .... 820
Nerve-cell Body. Internal Mor-
phology ....... 822
TheDendrites ....... 822
TheAxone ........ 823
The Collaterals ....... 823
NERVE-FIBRES AND NERVES.
827
Origin and Termination of Nerves . . .
The Supporting Tissue Elements of the
Nerve System ....... 832
The Neuroglia ....... 832
Chemical Composition of Nerves .... 833
THE CENTRAL NERVE SYSTEM.
Preliminary Considerations ..... 833
The Spinal Cord.
External Morphology of the Spinal Cord . 835
The Enlargements of the Spinal Cord . . 837
Conus .......... 838
Filum ...... ... 838
Fissures and Grooves of the Spinal Cord . . 838
Columns of the Spinal Cord ..... 839
Development of the Spinal Cord .... 840
Muscular Supply from Motor Segments of
the Cord ..........
Internal Structure of the Spinal Cord . . .
Gray Substance of the Cord ....
White Substance of the Cord . . .
Longitudinal Fibres of the Cord . . .
Marginal Tract of the Cord ....
Ground Bundles of the Dorsal Column .
Ground Bxindles of the Lateral Column
Ground Bundles of the Ventral Column
Myelinization of the Axones of the Cord
843
843
843
851
852
853
854
855
Dissection of the Spinal Cord ..... 856
The Membranes of the Cord.
The Spinal Dura
Structure
The Arachnoid
Structure
The Pia of the Cord .
856
858
858
859
859
The Pia of the Cord —
Structure .
Surgical Anatomy .
860
860
The Brain or Encephalon.
General Appearance and Topography of
the Brain , . 860
Dimensions of the Brain ' 862
The Development of the Brain and the
Usual Classifications of its Subdivisions . 863
Brief Consideration of the Phases of Devel- '
opment of the Brain-tube .... 865
The Fore-brain 865
The Mid-brain 869
The Hind-brain 869
Flexures of the Brain-tube 869
Dorsal and Ventral Lamina? or Longitudinal
Zones of the Brain 870
Descriptive Anatomy of the Adult Human Brain.
Parts derived from Hind-brain (Rhomben-
cephalon) 874
The Oblongata 874
Fissures of Oblongata 874
Areas of Oblongata 875
The Pyramids 875
Lateral Area 876
Dorsal Area 876
The Pons and Pre-obloiigata 877
The Ventral Surf ace 877
The Pre-oblongata 878
The Fourth Ventricle of the Brain . . . 878
"Floor" of the Fourth Ventricle . . 879
Membranous Portion of the "Roof" of
the Fourth Ventricle 881
Internal Structure of the Postoblongata . . 881
Pyramidal Decussation 881
Decussation of the Lemnisci .... 882
The Formatio Reticularis .... 884
TheRaphe 885
TheRestis 885
The Nucleus of the Olive or Inferior
Olivary Nucleus 885
The Arcuate Fibre Systems .... 886
Internal Structure of the Pons and Pre-
oblongata 887
The Transverse Fibres 887
The Longitudinal Fibres 887
The Nuclei Pontis 887
The Pre-oblongata 887
The Superior Olivary Nucleus . . . 887
The Nucleus Incertus 888
Fibre-tracts in the Pre-oblongata . . . 888
The Medial Lemniscus 888
The Lateral Lemniscus 888
The Medial Longitudinal Bundle . . 888
The Cerebellar Peduncle 888
Summary of Gray Masses in the Pre-oblon-
gata 888
CONTENTS
xxi
PAGE
Central Connections of the Cranial Nerves
attached to the Hind-brain . . . . 888
The Nuclei of Origin 889
The Nuclei of Termination .... 889
The Hypoglossal Nerve 889
The Accessory Nerve 890
The Vagus and Glosso-pharyngeal Nuclei 890
The Acoustic Nerve 892
The Facial Nerve 893
The Abducent Nerve 894
The Trigeminal Nerve 894
The Cerebellum 895
Lobes and Fissures of the Cerebellum . 896
TheLingula 897
The Central Lobe 897
The Culminal Lobe ..... 897
The Clival Lobe 898
The Cacuminal Lobe .... 898
The Tuberal Lobe 898
The Gracile Lobe . . . . .898
The Pyramidal Lobe .... 898
The Uvular Lobe 898
The Nodular Lobe 898
The Internal Structure of the Cere-
bellum 899
Isolated Gray Masses or Nuclei of the
Cerebellum 899
The Cerebellar Peduncles 900
The Medullary Vela 901
The Fibres Proper of the Cerebellum . 902
Microscopic Appearance of the Cerebel-
lar Cortex 902
Weight of the Cerebellum .... 903
The Mid-brain - ... 904
External Morphology 905
ThePregemina 905
The Prebrachium 905
The Postgeniculum 905
TheCrura 905
The Tamia Pontis 906
The Cimbia or Tractus Peduncu-
laris Transversus 906
Internal Structures of the Mid-brain . 906
The Aqueduct and Central Gray
Aqueduct 907
The Substantia Nigra or Interca-
latum 907
The Quadrigemina 907
The Tegmen turn 908
Fountain Decussation . . . .910
The Crusta or Pes .... 910
Summary of the Gray Masses in the
Mid-brain 910
Deep Origin of Cranial Nerves Arising
in the Mid-brain . . . . .910
The Trochlear-nerve Nucleus . . 910
The Oculomotor-nerve Nucleus . 911
Parts Derived from the Fore-brain . . .911
External Morphology 911
TheThalami ....
The Tuberculum Anterius . 913
Internal Structure of the
Thalamus and its Connec-
tions 914
The Connections of the Thala-
mus 914
TheEpiphysis 915
Structure 915
Postcommissure . . . . 915
Postperforatum . . . • 916
The Albicantia 916
Third Ventricle 916
External Morphology of the Optic Por-
tion of the Hypothalamus . . 917
TheTuber 917
The Hypophysis
TheTerma 917
The Optic Tract and its Central
Connections 917
Chiasni 919
The Cerebral Hemispheres 919
External Morphology 919
Configuration of Each Hemicere-
brum 922
Cerebral Fissures and Gyres . . 922
Cerebral Lobes and Fissures . . 923
The Interlobar Fissures . . . 924
The Sylvian Fissure and its
Kami 924
The Central Fissure ... 926
The Occipital Fissure ... 926
The Calcarine Fissure ... 926
The Frontal Lobe 926
The Parietal Lobe 930
Gyres of the Parietal Lobe
The Occipital Lobe 931
The Temporal Lobe 931
Gyres of the Temporal Lobe . 932
Thelnsula .... . . 933
The Rhinencephalon or Olfactory
Lobe 934
Internal Configuration of the Cerebral
Hemispheres 938
The Cortex 939
TheCallosum 939
Development of . . . .941
The Lateral Ventricles . . . .941
The Choroid Fissure or Rima . . 946
The Paraplexus and Velum . . 946
The Hippocampus and Fornix . . 947
The Septum Lucidum .... 952
The Precommissure 952
The Gray Masses in the Hemicere-
brum 952
TheCaudatum
The Lenticula
The Amygdala
TheClaustrum
The Internal Capsule ....
The External Capsule ....
Intimate Structure of the Cere-
bral Cortex and its Special Type
in Different Regions .... 958
Special Types of Gray Substance . 959
Summary of the Cerebral Fibre
Systems 961
Connections of the Striatum . . 964
The Olfactory Pathways .
Peripheral Pathway .... 964
Central Pathway 964
Weight of the Brain .... . . 965
Cortical Localization and Function.
Motor Area . . .
Sensor Area
The Language Areas 968
The Association Areas 969
Cranio-cerebral Topography .... 970
The Meninges or Meningeal Membranes of
the Brain.
Dissection
The Dura of the Brain
Structure
The Arteries of the Dura
The Veins of the Dura .
The Lymphatics of the Dura
The Nerves of the Dura .
Processes of the Dura ....
TheFalx
TheTentorium
TheFalcula
The Diaphragma Sellse .
The Arachnoid of the Brain ....
The Subarachnoid Space ....
Structure
The Arachnoid Villi or Pacchionian Bodies
972
972
973
974
974
974
974
975
975
975
976
976
976
977
977
979
XX11
CONTENTS
PAGE
The Pia of the Brain 980
The Velum or the Fela Chorioidea
Superior 981
THE SPINAL NERVES.
The Roots of the Spinal Nerves . . 982
The Ventral Root .....'. 982
The Dorsal Root 982
The Ganglia of the Spinal Nerves . . . 983
Distribution of the Spinal Nerves . . . 984
Points of Emergence of the Spinal Nerve . 985
The Cervical Nerves.
The Roots of the Cervical Nerves . . . 986
The Dorsal Division of the Cervical Nerves 986
The Ventral Division of the Cervical
Nerves 988
The Cervical Plexus 989
Superficial Branches 989
Deep Branches, Internal Series . . 992
Surgical Anatomy 993
Deep. Branches, External Series . . 993
Surgical Anatomy 994
The Brachial Plexus 994
Relations 998
Branches 998
Surgical Anatomy 1009
The Thoracic or Dorsal Nerves.
The Roots of the Thoracic Nerves . . . 1010
The Dorsal Divisions of the Thoracic Nerves 1010
The Medial Branches 1010
The Lateral Branches 1010
The Cutaneous Branches .... 1010
The Ventral Divisions of the Thoracic
Nerves or the Intercostal Nerves . 101 1
The Ventral Division of the First
Thoracic Nerve 1011
The Ventral Divisions of the Upper
Thoracic Nerves 1011
The Ventral Divisions of the Lower
Thoracic Nerves 1013
The Last Thoracic Nerve .... 1014
Surgical Anatomy 1014
The Lumbar Nerves.
The Roots of the Lumbar Nerves . . . 1015
The Dorsal Divisions of the Lumbar Nerves 1015
Medial Branches 1015
Lateral Branches 1015
The Ventral Divisions of the Lumbar Nerves 1015
The Lumbar Plexus 1016
Branches 1017
The Sacral and Coccygeal Nerves.
The Roots of the Upper Sacral Nerves . . 1023
The Dorsal Divisions of the Sacral Nerves . 1023
The Upper Sacral Nerves .... 1023
The Lower Sacral Nerves .... 1023
The Ventral Divisions of the Sacral Nerves 1025
The Dorsal Divisions of the Coccygeal
Nerve 1025
The Ventral Division of the Coccygeal
Nerve 1025
The Sacral or Sciatic Plexus and the Pudic
or Pudendal Plexus 1026
Branches 1027
The Coccygeal Plexus 1034
Surgical Anatomy 1034
THE CRANIAL NERVES.
The First or Olfactory Nerve.
Surgical Anatomy 1038
The Second or Optic Nerve.
TheChiasm
Surgical Anatomy ....
1038
1038
The Third or Oculomotor Nerve.
Surgical Anatomy . 1040
The Fourth or Trochlear Nerve.
Branches of Communication .... 1041
Branches of Distribution 1041
Surgical Anatomy 1041
The Fifth, Trigeminal or Trifacial Nerve.
The Gasserian or Semilunar Ganglion . . 1042
Ophthalmic Nerve 1043
Branches 1043
The Superior Maxillary Nerve .... 1046
Branches 1046
The Mandibular or Inferior Maxillary Nerve 1050
Branches 1051
Surface Marking 1055
Surgical Anatomy 1055
The Sixth or Abducent Nerve.
Branches of Communication 1057
Surgical Anatomy 1058
The Seventh or Facial Nerve.
Branches of Communication 1060
Branches of Distribution 1060
Surgical Anatomy 1064
The Eighth or Acoustic Nerve.
The Cochlear Nerve 1064
The Vestibular Nerve 1065
Surgical Anatomy 1065
The Ninth or Glosso-Pharyngeal Nerve.
The Superior or Jugular Ganglion . . . 1066
The Inferior or Petrous Ganglion . . . 1066
Branches of Communication . . . 1067
Branches of Distribution .... 1067
The Gustatory Path 1067
Surgical Anatomy 1067
The Tenth, Vagus or Pneumogastric Nerve.
The Ganglion of the Root of the Vagus
Nerve 1069
Connecting Branches 1069
The Ganglion of the Trunk of the Vagus
Nerve 1069
Connecting Branches 1069
Surgical Anatomy 1072
The Eleventh or Accessory Nerve.
The Bulbar or Vagal Part of the Accessory
Nerve ". 1073
The Spinal Portion of the Accessory Nerve 1074
Surgical Anatomy 1074
The Twelfth or Hypoglossal Nerve.
Branches of Communication .... 1075
Branches of Distribution 1076
Surgical Anatomy 1077
THE SYMPATHETIC NERVE SYSTEM.
Structure of the Sympathetic System . . 1079
The Gangliated Cord.
The Cervical Portion of the Gangliated Cord 1081
The Superior Cervical Ganglion . . 1081
The Middle Cervical or Thyroid Gan-
glion 1085
The Inferior Cervical Ganglion . . . 1086
Surgical Anatomy 1087
CONTENTS
XXlll
The Thoracic Portion of the Gangliated Cord 1087 The Cardiac Plexus —
The Lumbar Portion of the Gangliated Cord 1089 The Superficial or
The Pelvic or Sacral Portion of the Gangli-
ated Cord . 1089
The Great Plexuses of the Sympathetics.
The Cardiac Plexus 1090
The Great or Deep Cardiac Plexus . 1090
Ventral Cardiac
Plexus
The Pulmonary Plexus
The CEsophageal Plexus .
The Epigastric or Solar Plexus
The Hypogastric Plexus .
The Pelvic or Sacral Plexus
1090
1091
1091
1091
1095
1095
THE ORGANS OF SPECIAL SENSE.
THE TONGUE.
The Body 1097
The Base or Root 1097
The Apex or Tip 1097
The Dorsum of the Tongue 1097
The Margin of the Tongue 1097
The Under or Inferior Surface .... 1097
Structure of the Tongue 1098
THE NOSE.
The Outer Nose.
Structure 1106
The Nasal Fossae.
The Anterior Nares 1108
The Posterior Nares 1108
Outer Wall 1109
The Inner Wall 1110
Surgical Anatomy 1112
THE EYE.
The Fascia or Capsule of Te"non . . .1113
The Tunics of the Eye.
The Fibrous or External Coat : The Sclerotic
and Cornea 1117
The Sclera or Sclerotic Coat . . .1117
The Cornea . 1118
The Choroid, Ciliary Body, and Iris; the
Tunica Media ; the Uveal Tract . . 1121
The Choroid . . . ' 1121
Tapet.um 1124
The Ciliary Body 1125
The Iris 1127
The Tunica Interna or Retina .... 1130
The Refracting Media.
The Aqueous Humor 1138
The Vitreous Body 1139
The Crystalline Lens . 1140
Surgical Anatomy of the Eye .... 1144
The Appendages of the Eye.
The Eyebrow 1147
The Eyelid . . 1147
The Meibomian or Tarsal Glands . . 1 149
The Conjunctiva
The Lachrymal Apparatus .
The Lachrymal Glands .
The Lachrymal Sac .
The Nasal" Duct ....
Surface Form
Surgical Anatomy ....
THE EAR.
The External Ear.
The Pinna or Auricle ....
Structure of the Pinna .
The External Auditory Canal
The Cartilaginous Portion .
The Osseous Portion
Surface Form .
1150
1151
1151
1152
1152
1152
1153
1154
1156
1158
1158
1159
1160
The Middle Ear, Drum or Tympanum.
The Tympanic Cavity 1160
The Drumhead or Membrana Tympani . 1165
The Ossicles of the Tympanum . . . .1168
The Malleus or Hammer .... 1168
The Incus or Anvil 1169
The Stapes or Stirrup 1170
The Internal Ear or Labyrinth.
The Osseous Labyrinth 1174
The Vestibule 1174
The Semicircular Canals . . . .1175
The Cochlea 1175
The Membranous Labyrinth 1179
The Utricle 1179
The Saccule 1180
The Membranous Semicircular Canals . 1180
Surgical Anatomy 1186
THE SKIN.
The Corium, Cutis Vera, Dermis or True
Skin H90
The Cuticle, Scarf Skin or Epidermis . . 1191
The Appendages of the Skin . . . .1195
The Nails 1195
The Hairs 1197
The Sudoriferous or Sweat-glands . . 1200
The Sebaceous Glands . .1201
THE ORGANS OF DIGESTION.
THE ALIMENTARY CANAL.
The Mouth, Oral or Buccal Cavity.
The Vestibule 1204
The Cavity of the Mouth Proper . . . 1204
The Lips 1204
The Cheeks 1205
The Gums 1205
The Teeth 1205
General Characters 1205
Temporary, Deciduous or Milk Teeth . 1206
Permanent Teeth 1206
Arrangement of the Teeth .... 1208
Structure of the Teeth 1210
Development of the Teeth . . . .1214
The Palate 1220
The Hard Palate . 1220
The Palate —
The Soft Palate or Velum Pendulum
Palati 1221
The Tonsil or Amygdala .... 1223
The Salivary Glands 1224
The Parotid Gland 1224
Surface Form 1225
The Submaxillary Gland .... 1226
The Sublingual Gland 1227
Structure of Salivary Glands . . . 1227
Surface Form . 1229
The Pharynx.
The Nasal Part ....
The Oral Part
The Laryngeal Part
Structure
1231
1231
1232
1232
XXIV
CONTENTS
Surgical Anatomy of the Mouth, Cheeks,
Lips, Gums, Tonsils, Palate, Salivary
Glands and Pharynx 1234
The (Esophagus.
Relations 1237
Anomalies 1238
Structure 1238
Movements and Innervations of the (Esoph-
agus 1240
Surgical Anatomy 1240
THE ABDOMEN.
Boundaries 1241
Development of the Alimentary Canal, Vis-
cera and Peritoneum 1245
Development of the Alimentary Canal . . 1247
The Peritoneum.
Structure ' of the Peritoneum .... 1256
Retro-peritoneal Fossae 1270
Surgical Anatomy 1274
The Stomach.
Relations of the Stomach ....
Surfaces
The Cardia
The Pylorus
Alterations in Position
Supports of the Stomach ....
Structure
Movements and Innervation of Stomach
Surface Form
Surgical Anatomy
The Small Intestine.
The Duodenum
The First or Superior Portion .
The Second or Descending Portion
The Third, Pre-aortic, Horizontal or
Transverse Portion
The Fourth or Ascending Portion
The Jejunum and Ileum
Differences between the Jejunum and
Ileum
The Jejunum
The Ileum
Structure of the Small Intestine, including
the Duodenum .
1277
1277
1278
1279
1280
1281
1281
1288
1288
1288
1290
1292
1293
1293
1294
1297
1297
1297
1297
1298
The Large Intestine.
The Caecum 1308
The Vermiform Appendix . . . .1311
The Ileo-ca3cal Valve or the Valve of
Bauhin 1315
The Colon 1317
The Ascending Colon 1317
The Transverse Colon 1317
The Descending Colon 1317
The Sigmoid Flexure, Pelvic Colon or
Sigmoid Colon 1317
The Rectum 1320
The Common Anal Canal .... 1323
Structure of the Large Intestine . . . 1324
Movements and Innervations of the Intes-
tines 1330
Surface Form of the Intestines . . . .1331
Surgical Anatomy of the Intestines . .1331
The Liver.
The Superior Area or Surface .... 1336
The Anterior Area or Surface .... 1336
The Lateral or Right Area or Surface . . 1336
The Under or Visceral Area or Surface . 1336
The Posterior Area or Surface .... 1337
Fissures of the Liver 1338
Lobes of the Liver 1339
Supports and Movability of the Liver . . 1342
Abnormalities of the Liver 1342
Structure of the Liver 1345
The Excretory Apparatus of the Liver . 1349
The Hepatic Duct 1350
The Gall-bladder 1350
The Cystic Duct 1351
Surface Relations of the Liver .... 1353
Surgical Anatomy of the Liver .... 1354
The Pancreas.
Dissection
The Right Extremity or Head of the Pan-
creas
The Neck of the Pancreas
The Body and Tail of the Pancreas
Structure of the Pancreas
Surface Form
Surgical Anatomy
1355
The Spleen.
Surface of the Spleen
Supports and Movability of the Spleen
Surface Form
Surgical Anatomy
1357
1357
1357
1359
1360
1360
1361
1363
1366
1366
ORGANS OF VOICE AND RESPIRATION.
THE LARYNX.
The Cartilages of the Larynx . . . .1370
The Thyroid Cartilage 1370
The Cricoid Cartilage 1371
The Arytenoid Cartilages . . . .1372
The Cornicula Laryngis or Cartilages
of Santorini 1373
The Cuneiform Cartilages or Cartilages
of Wrisberg 1373
The Epiglottis or the Cartilage of Epi-
glottis 1373
Structure of the Larynx 1373
Interior of the Larynx 1376
THE TRACHEA AND BRONCHI.
Relations 1384
The Right Bronchus 1384
The Left Bronchus 1386
Structure of the Trachea 1386
Surface Form of Larynx 1389
Surgical Anatomy of Larynx and Trachea . 1389
THE PLEURAE.
Reflections of the Pleura 1392
Structure of the Pleura 1395
Surgical Anatomy 1395
THE MEDIASTINAL SPACE, INTERPLEURAL SPACE
OR MEDIASTINUM.
The Superior Mediastinum 1
The Anterior Mediastinum 1
The Middle Mediastinum 1396
The Posterior Mediastinum 1397
THE LUNGS.
Apex of the Lungs • 1
Base of the Lungs 1398
Surfaces of the Lungs 1
Borders of the Lungs 1
Lobes of the Lungs 1402
CONTENTS
xxv
The Root of the Lung
The Foetal Lung .
Structure of the Lung
The Bronchus .
PAGE
1402
1402
1403
1403
Changes in the Structure of the Bronchi in
the Lungs 1403
Surface Form of the Lungs 1405
Surgical Anatomy of the Lungs .... 1406
THE DUCTLESS GLANDS.
THE THYROID BODY OR GLAND.
Accessory Thyroids 1409
Structure of the Thyroid 1409
Surgical Anatomy 1411
THE PARATHYROID GLANDS 1412
Structure T 1413
Surgical Anatomy 1413
THE THYMUS GLAND.
Structure of the Thymus Gland .... 1414
THE CAROTID GLAND OR CAROTID BODY.
Surgical Anatomy
THE COCCYGEAL GLAND OR COCCYGEAL
BODY
THE PARASYMPATHETIC BODIES
1417
1417
1417
THE URINARY ORGANS.
THE KIDNEYS.
Surfaces of the Kidneys . . . . . . 1420
Borders of the Kidneys 1423
General Structure of the Kdney . . . 1423
Surface Form , 1434
Surgical Anatomy 1434
THE URETER.
The Ureter Proper 1435
Relations of the Ureter 1435
Structure of the Ureter 1436
Surgical Anatomy 1437
THE SUPRARENAL CAPSULE OR GLAND.
Relations of the Suprarenal Capsule . . 1437
Accessory Suprarenal Glands .... 1438
Structure of Suprarenal Glands '. 1438
THE CAVITY OF THE PELVIS.
Boundaries
Contents
1440
1440
The Urinary Bladder.
Surfaces . . - 1442
The Fundus or Base 1443
The Summit or Apex 1445
The Urachus or Middle Umbilical Ligament 1445
Structure of the Bladder 1446
Objects Seen on the Inner Surface of Bladder 1447
Surface Form 1449
Surgical Anatomy 1449
The Male Urethra.
The First or Prostatic Portion .... 1450
The Second, Muscular or Membranous Por-
tion 1451
The Third, Penile, Pendulous, Cavernous or
Spongy Portion 1452
Structure of Male Urethra 1453
Surgical Anatomy 1454
The Female Bladder and Urethra.
The Female Urethra 1455
Structure 1455
THE MALE ORGANS OF GENERATION.
THE PROSTATE GLAND.
The Base , 1461
The Apex 1461
Surfaces 1461
The Lateral Lobes 1461
The So-called Middle Lobe 1461
Structure 1462
Surgical Anatomy 1462
COWPER'S GLANDS.
Structure 1463
THE PENIS.
The Root 1464
The Body of the Penis 1465
Structure of the Penis 1465
Surgical Anatomy 1470
THE TESTICLES AND THEIR COVERINGS.
Descent of the Testis.
Surgical Anatomy 1472
The Coverings of the Testicle.
The Testicular Bag or Scrotum .... 1472
The Intercolumnar or Spermatic Fascia . 1474
The Cremasteric Fascia 1474
The Infundibuliform Fascia 1475
The Tunica Vaginalis 1476
The Spermatic Cord.
Structure 1476
Surgical Anatomy 1478
The Testicles.
The Tunics of the Testicle 1481
Structure of the Testicle and Epididymis . 1482
THE SEMINAL VESICLES.
The Ejaculatory Ducts 1487
Structure 1487
Surgical Anatomy 1487
THE FEMALE ORGANS OF GENERATION.
EXTERNAL ORGANS.
The Large Lips or Labia Majora . . . 1489
The Small Lips, Nympha; or Labia Minora . 1490
The Vestibule . 1491
The Clitoris . .
Glands of Bartholin
The Vaginal Bulb .
1493
1495
1495
XXVI
CONTENTS
Relations
Structure
INTERNAL ORGANS.
The Vagina.
The Womb or Uterus.
1496
1496
The Fundus 1499
The Body of the Uterus 1499
The Neck or Cervix Uteri 1500
Folds and Ligaments 1501
The Cavity of the Uterus 1503
The Cavity of the Cervix or Cervical Canal 1503
Surgical Anatomy 1508
THE ADNEXA OR APPENDAGES OF UTERUS.
The Fallopian Tube.
Structure of the Fallopian Tube . . 7 1510
The Epo-ophoron, Parovarium or Organ of
Rosenmiiller
The Paro-ophoron
The Ovary.
Supports and Connections of the Ovary
Descent of the Ovary
The Ovary at Different Ages .
Structure
Surgical Anatomy of the Appendages
The Mammary Gland.
Description of a Well-developed Breast
The Nipple .... ..'.-'*
Prolongation of Mammary Tissue .
Structure of Mammary Gland and Nipple .
Surgical Anatomy . .
The Male Breast
Surgical Anatomy
1511
1512
1513
1513
1513
1514
1515
1516
1516
1518
1518
1520
1522
1522
THE SURGICAL ANATOMY OF INGUINAL AND FEMORAL
HERNIA.
Dissection 1523
Inguinal Hernia.
Oblique Inguinal Hernia 1532
Congenital Hernia 1535
Infantile and Encysted Hernia . . 1535
Hernia into Funicular Process
Direct Inguinal .Hernia .
Femoral Hernia.
Varieties of Femoral Hernia
1535
1535
1536
SURGICAL ANATOMY OF THE PERINEUM.
Dissection . ...... 77. 1537 1 Surgical Anatomy
Ischio-rectal Region.
Dissection ...... .... 1538
„, D .
The Permaeum Proper ^n the Male.
Position of the Viscera at the Outlet of the
Pelvis .......... 1552
1553
The Female Perineum.
The Pelvic Fascia ........ 1556
The obturator Fascia ...... 1558
The Recto-vesical Fascia or the Visceral
Layer of the Pelvic Fascia .... 1558
CHRONOLOGICAL TABLE OF THE DEVELOPMENT OF THE FOSTUS .... ."" . . . . 1559
INDEX . 1561
DESCRIPTIVE AND SURGICAL
ANATOMY.
OSTEOLOGY-THE SKELETON.
T
HE entire skeleton in the adult consists of 200 distinct bones. These are:
The spine or vertebral column (sacrum and coccyx included) .... 26
Cranium 8
Face 14
Hyoid bone, sternum, and ribs 26
Upper extremities 64
Lower extremities 62
200
In this enumeration the patellae are included as separate bones, but the smaller
sesamoid bones and the ossicula auditus are not reckoned. The teeth belong to
the tegumentary system. Different anatomists make different computations as
to the number of bones in the skeleton. Some describe the skeleton as containing
206 distinct bones, adding the ossicles of the ear to the previously stated number.
By adding the epipteric bones, the sphenoidal turbinal bones, the sesamoid bones,
and others, the number may be greatly augmented.
Bones are divisible, according to their shape, into four classes: long, short, flat,
and irregular.
Long Bones. — The long bones are found in the limbs, where they form a
system of levers, which sustain the weight of the trunk and confer the power
of locomotion. A long bone consists of a shaft and two extremities. The shaft
is a hollow cylinder, contracted and narrowed to afford greater space for the
bellies of the muscles; the walls consist of dense, compact tissue of great thick-
ness in the middle, but becoming thinner toward the extremities; the spongy
tissue is scanty, and the bone is hollowed out in its interior to form the medullary
canal. The extremities are generally somewhat expanded for greater convenience
of mutual connection, for the purpose of articulation, and to afford a broad
surface for muscular attachment. Here the bone is made up of spongy tissue
with only a thin coating of compact substance. The long bones are not straight,
but curved, the curve generally taking place in two directions, thus affording
greater strength to the bone. The bones belonging to this class are the clavicle,
humerus, radius, ulna, femur, tibia, fibula, metacarpal and metatarsal bones, and
the phalanges.
Short Bones. — Where a part of the skeleton is intended for strength and com-
pactness, and its motion is at the same time slight and limited, it is divided into
a number of small pieces united together by ligaments, and the separate bones
are short and compressed, such as the bones of the carpus and tarsus. These
bones, in their structure, are spongy throughout, excepting at their surface, where
3 ( 33 )
34 THE SKELETON
there is a thin crust of compact substance. The patellae also, together with the
other sesamoid bones, are by some regarded as short bones.
Flat Bones. — Where the principal requirement is either extensive protection
or the provision of broad surfaces for muscular attachment, we find the osseous
structure expanded into broad, flat plates, as is seen in the bones of the skull
and the shoulder-blades. Flat bones are composed of two thin layers of com-
pact tissue enclosing between them a variable quantity of cancellous tissue. In
the cranial bones these layers of compact tissue are familiarly known as the tables
of the skull ; the outer table is thick and tough ; the inner table is thinner, denser,
and more brittle, and hence is termed the vitreous table. The intervening can-
cellous tissue is called the diploe. The flat bones are: the occipital, parietal, frontal,
nasal, lachrymal, vomer, scapula, os innominatum, sternum, ribs, and patella.
Irregular Bones. —The irregular or mixed bones are such as, from their pecu-
liar form, cannot be grouped under either of the preceding heads. Their structure
is similar to that of other bones, consisting of a layer of compact tissue externally
and of spongy, cancellous tissue within. The irregular bones are: the vertebrae,
sacrum, coccyx, temporal, sphenoid, ethmoid, malar, superior maxilla, inferior maxilla,
palate, inferior turbinated, and hyoid.
Surfaces of Bones. — If the surface of any bone is examined, certain eminences
and depressions are seen, to which descriptive anatomists have given the following
names.
These eminences and depressions are of two kinds: articular and non-articular.
Well-marked examples of articular eminences are found in the heads of the
humerus and femur and of articular depressions in the glenoid cavity of the
scapula and the acetabulum. Non-articular eminences are designated according
to their form. Thus a broad, rough, uneven elevation is called a tuberosity; a
small, rough prominence, a tubercle; a sharp, slender, pointed eminence, a spine;
a narrow, rough elevation, running some way along the surface, a ridge, line, or
crest.
The non-articular depressions are also of very variable form, and are described
as fossae, grooves, furrows, fissures, notches, sulci, etc. These non-articular emi-
nences and depressions may receive blood-vessels, nerves, tendons, ligaments, or
portions of organs, or may serve to increase the extent of surface for the attach-
ment of ligaments and muscles. They are usually well marked in proportion to
the muscular development of the subject.
A prominent process projecting from the surface of a bone which it has never
been separate from or movable upon is termed an apophysis (from d^ot/'Uffa;, an
excrescence) ; but if such process is developed as a separate piece from the rest of
the bone, to which it is afterward joined, it is termed an epiphysis (from iKiyufftz,
an accretion). The main part of the bone, or shaft, which is formed from the
primary centre of ossification, is termed the diaphysis, and is separated, during
growth, from the epiphysis by a layer of cartilage, at which growth in length of
the bone takes place. Some bones are hollow and contain sinuses, which are
spaces for air. Canals or foramina are channels or openings in bone through
which nerves or vessels pass.
Structure of Bone. — Bone is a highly specialized form of connective tissue.
In reality, it is white fibrous tissue, calcified and structurally modified until it
becomes osseous tissue. Bone is not simply a crude mass resulting from the
calcification of cartilage or fibrous tissue; it is a distinct tissue, of a definite struc-
ture, the constituent parts of which are arranged symmetrically. Its structure
varies somewhat in different vertebrates.1
1 Arquitectura del Aparato de Sustentacion en los Vertebrados. Por el Dr. Saturnine Garcia Hurtado. Our
description applies to human bone.
STRUCTURE OF BONE
35
There are two varieties of bone: dense or compact bone (substantia compacta],
and cancellous, loose, or spongy bone (substantia spongiosa).
Compact Bone is dense, like ivory, and is always placed upon the exterior of
bones. Even this apparently compact tissue is porous; it differs from cancellous
bone in the greater density of its tissue and in the arrangement of its osseous
plates into Haversian systems. Compact bone is surrounded by periosteum.
OSTEOGENETIC
CELLS
LAMELL/E
LACUN/E
CANALIOUL
HAVERSIAN
CANAL
COMPLETE
HAVERSIAN
SYSTEM
FIG. 1. — Diagram of the structure of osseous tissue. A small part of a transverse section of the shaft of a long
bone is shown. At the uppermost part is the periosteum covering the outside of the bone ; at the lowermost part
is t he endosteum lining the marrow-cavity. Between these is the compact tissue, consisting largely of a series of
Haversian systems, each being circular in outline and perforated by a central canal. In the first one is shown
only the area occupied by a system; in the second is seen the concentric arrangement of the lamellae; and in the
others, respectively, canaliculi; lacuna1; lacunae and canaliculi; the contents of the canal, artery, vein, lymphatic
and areolar tissue; lamellae, lacunae, and canaliculi; and, finally, all of the structures composing a complete sys-
tem. Between the systems are circumferential and intermediate lamellae, only a few of which are represented as
lodging lacunae, though it is to be understood that the lacunae are in all parts. The periosteum is seen to be
made up of a fibrous layer and a vascular layer, and to have upon its attached surface a stratum of cells. From
the fibrous layer project inward the rivet-like fibres of Sharpey. (F. H. Gerrish.)
The outer portion of the wall of a long bone, the cortex of the head of a bone,
and the outer and inner layers of a flat bone are composed of compact osseous
tissue, which is the hardest substance in the body with the exception of dentine
and enamel ; it is tough and elastic, and much force is required to break it.
Cancellous Bone is found in the interior of bones. The name, which means
lattice-work, indicates the structure, which consists of slender fibres and lamellse
joined to form a reticulum, the small meshes of which are marrow-spaces. The
36 THE SKELETON
spicules of cancellous bone contain lacunae and canaliculi, but no Haversian
systems. In some regions the inner portion of the wall of a long bone, about the
marrow-cavity, is composed of cancellous bone. Toward each extremity of the
shaft the amount of cancellous tissue increases, the marrow-cavity diminishes in
size, and the cancellous tissue is arranged in lines that approach each other toward
the extremity, like the sides of an arch, and form a support for the epiphysis
(Fig. 131). In the epiphysis the bone-plates are, as a rule, at right angles to
the plane of the articular surface (the lines of greatest pressure) ; and they are
bound together or strengthened by other bone-fibres, which are usually in corre-
spondence with the planes of the articulation (the lines of greatest tension) (Fig.
164). The nearer the bone-spicules are to the medullary cavity the stronger they
are (Hurtado).
In the flat and the irregular bones, the cancellous tissue is between the layers
of compact bone, and is called the diploe.
A Short Bone is composed chiefly of cancellous tissue, which is encased in a
thin coat of compact substance (substantia corticalis).
A Long Bone consists of a shaft, or diaphysis, and two extremities, or epiphyses.
The shaft is an osseous tube, the outer layer of which is compact, and the inner
layer of which is cancellous. It surrounds the medullary cavity (cavum medullare),
which, in the recent condition, contains the medulla, or marrow (medulla ossium),
which substance enters into the nearest Haversian canals. This cavity is widest
at the centre of the shaft, and narrows toward the ends, where it is encroached
upon by the cancellous layer which lies within the compact layer.
There are two varieties of marrow: Yellow marrow (medulla ossium flava) is
found in the medullary cavities of the shafts of the long bones. It is composed
of a network of fibrous tissue carrying many blood-vessels, fat-cells, and a few
large nucleated masses of protoplasm — the true marrow-cells, or myelocytes.
The yellow color, of the marrow is due to fat. Yellow marrow is derived from
red marrow by an increase in fat and diminution in marrow elements; it plays
no part in blood-formation. At the periphery of the marrow cavity the fibrous
tissue of the network forms a firm, fibrous membrane lining the cavity. This
represents an inner periosteum, and is called the endosteum.
Red marrow (medulla ossium rubra) is found in the diploe of the cranial bones, in
the cancellous tissue of the vertebrae, ribs, and sternum, and in the articular ends
of the long bones. Red marrow contains much less fat and is less solid than yellow
marrow. It consists of a delicate network of connective tissue, supporting a
dense capillary plexus ; some fat; and numerous cellular elements. The delicate
fibrous membrane surrounding red marrow is called the endosteum. The
cellular elements of red marrow (Fig. 2) comprise, first, marrow-cells, or myelocytes,
which are protoplasmic masses, capable of amoeboid movements, and containing
large nuclei. They are not found in normal blood, but are abundant in leukaemia;
second, small, nucleated, reddish cells called erythroblasts, resembling the nucleated
red cells of the blood of the embryo, and eventually by the loss of their nuclei
becoming red blood-corpuscles; third, non-nucleated red blood-corpuscles; fourth,
giant-cells containing one or more nuclei. They are varieties of leukocytes. The
leukocyte group also contains the osteoclasts, eosinophiles, and mast-cells.
Gelatinous or mucoid marrow is formed by the absorption of the fat and the
cellular elements of yellow marrow, and by the serous infiltration of the inter-
cellular substance. It is produced by starvation, old age, and certain pathological
conditions.
Each extremity of a long bone is separated from the shaft by a layer of car-
tilage known as the cambium layer, the epiphysial cartilage, or the epiphysial
disk (Fig. 8). Growth from the cartilages causes an increase in the length of
the bone. The cartilages ossify during development, and effect a bony union
STRUCTURE OF BONE
37
between the shaft and the head of the bone. Certain bony processes are
separated from the bone by cartilage, which later ossifies.
A Flat Bone is composed of two layers of compact bone with a layer of can-
cellous bone (the diploe) interposed. There is no general marrow-cavity; but
the spaces between the bone-spicules intercommunicate and contain marrow.
FIG. 2. — Cells of red marrow of the guinea-pig, a-d. Myelo-plaques. e-i. Marrow-cells proper, j-t. Erythro-
blasts — some in process of division. (Schiifer.)
The Periosteum is a fibrous membrane adhering to the surface of the bone in
nearly every .part except at the cartilage-covered extremities. When strong ten-
dons or ligaments are attached to the bone, the periosteum is incorporated with
them. By means of the periosteum many vessels reach and enter the hard bone
through Volkmann's canals. This is shown by stripping the periosteum from the
surface of living bone, when small bleeding points are seen, each of which
marks the entrance of a vessel from the periosteum. It thus becomes obvious
that the loosening of the periosteum, by depriving a portion of the bone of its
nourishment, may produce necrosis. The membrane is firmly attached to the
bone by trabeculse of fibrous tissue, which pene-
trate the bone at right angles to its surface, and
carry blood-vessels. These trabeculse are called
the fibres of Sharpey (Fig. 3). They do not di-
rectly enter the Haversian systems, but only the
circumferential and intermediate lamellae — parts
that are formed by periosteal action. Prolonga-
tions from some of these vessels reach the Haver-
sian canals, and even the bone-marrow. In the
extremities of a long bone, vessels from the peri-
osteum penetrate the layer of compact bone and
reach the cancellous tissue. In the newborn and
in the young the periosteum is composed of three
layers: an outer or fibrous layer, containing some
blood-vessels, and composed of bundles of white
fibrous tissue; a middle or fibro-elastic layer, con-
taining some blood-vessels, fibrous tissue, and
much elastic tissue ; and an inner or osteogenetic layer, which is very vascular and
contains numerous cells, which are converted into osteoblasts. These are the
cells that form osseous tissue.
m
FIG. 3. — Fibres of Sharpey from the
parietal bone (adult man) isolated by
dissociation. (After Kolliker.)
38
THE SKELETON
Transverse Section of Compact Bone (Figs. 1, 4, and 6). — As previously stated,
dense bone differs from cancellous bone in the fact that the bone-plates of the
former are arranged in Haversian systems, so named from the anatomist
Havers. A Haversian system consists of a central canal, running in a more or
less longitudinal or slightly curved or. spiral direction and called the Haversian
canal ; from five to ten bone-plates, or lamellae, arranged concentrically around the
canal; gaps, called lacunae, between the lamellae, which spaces contain bone-cor-
puscles; minute channels, or canaliculi, radiating from the lacunae and passing
through the lamella? — some reaching other lacunae, some reaching the Haver-
sian canal, and others passing to adjacent Haversian systems. The canaliculi
contain processes from the bone-corpuscle. From a study of transverse sections
it would be thought that the lamellae always run longitudinally in straight lines
or in curves determined by pressure and tension; but Prof. Dixon proved that
in the human femur many of the bone-plates are arranged spirally, and thus
increased strength is obtained. The same is probably true of other bones.
FIG. 4. — Transverse section of compact tissue of bone. Magnified about 150 diameters. (Sharpey.)
There are four varieties of lamellae: (1) the periosteal, peripheral, superficial,
or external; (2) the Haversian, or concentric; (3) the interstitial, ground, or inter-
mediate; and (4) the perimedullary, or internal. The periosteal lamellae are some-
times called primary, as they are the first to appear, and are formed by the direct
transformation of the inner layer of the periosteum into bone. In the shaft of
a long bone there are several layers of periosteal lamellae, but no one layer is
extensive enough to surround the bone completely.
In the outer surface of the layer of periosteal lamellae depressions exist that
are known as Howship's foveolae, or lacunas. These depressions are made by
large cells, called osteoclasts, which destroy bone. There are no Haversian
canals in this outer layer, but there are some large channels that convey blood-
vessels into the bone, and are known as Volkmann's canals. Many small arteries
from the periosteum enter the periphery of the shaft, and also of the epiphyses.
A large trunk enters the shaft by the nutrient foramen (foramen nutricius), pass
along the nutrient canal (canalis nutricius), and reaches the medullary canal.
This vessel is called the nutrient artery.
The Haversian or concentric lamellae are circular layers arranged around a
central space, or canal, known as the Haversian canal. There is no fixed num-
ber of these layers, there being usually from five to ten. The layers of each system
are parallel to one another, but the layers of different systems cross at various
BLOOD-VESSELS OF BONE
39
angles. Between these layers are small, irregular spaces, called lacunae; and
extending radially out from the lacunae and piercing the various lamellae are
delicate canals, known as canaliculi, which connect the lacunae. The lacuna
nearest to the Haversian canal communicates with it by means of canaliculi;
and canaliculi also communicate with other Haversian systems. The Haversian
canal contains blood-vessels — an artery or a vein, or both an artery and a vein —
and a nerve. The vessel in the canal is covered with endothelial cells, and the
canal itself is lined with them. The space thus formed is a lymph-space, and
into these lymph-spaces the canaliculi empty. Beneath the periosteum and at
the periphery of the medullary cavity there are lymph-spaces that are in direct
communication with the canaliculi of the Haversian systems. In each lacuna is
a bone-cell— a corpuscle that almost fills the space, and sends arms, or processes,
out into the canaliculi (Fig. 5). This bone-cell is an osteoblast.
The interstitial or intermediate lamellae occupy the spaces between the
Haversian systems. They represent the remains of peripheral lamellae. They
are usually short and very
-Spe
lacunae
irregular, but possess
i 1*1*1*1
and canaliculi, which are ar-
ranged as in the Haversian
systems. The perimedullary
lamellae are irregular and few
in number.
FIG. 5. — Nucleated bone-cells and their
processes, contained in the bone-lacunae and
their canaliculi, respectively. From a section
through the vertebra of an adult mouse.
(Klein and Noble Smith.)
FIG. 6. — Combined transverse and longitudinal section of
compact bone. Off. Longitudinal Haversian canal and
anastomosing canals, o. Communicating with medullary
cavity. Si. Intermediate systems. Spe. Circumferential
lamellae. Spi. Perimedullary lamella;. os. Osteoblasts.
(Poirier and Charpy.)
The osteoblasts are irregular, flattened, stellate masses of protoplasm, pos-
sessing a number of processes. The protoplasm is granular, and each cell con-
tains a large and distinct nucleus. Osteoblasts are met with in the deeper layer
of the periosteum, in the endosteum, and in the lacunae.
Longitudinal Section of Compact Bone (Figs. 6 and 7). — We do not see con-
centric rings, as in a transverse section, but rows of lacunae parallel to the course
of the Haversian canals — and these canals appear like half-tubes instead of
circular spaces. The tubes are seen to branch and communicate, so that each
separate Haversian canal runs only a short distance. In other respects the
structure closely resembles that of a transverse section.
Lamellae of Cancellous Bone. — There are no Haversian canals, and canaliculi
open into the medullary spaces, which act as do the Haversian canals in com-
pact bone.
Blood-vessels of Bone. — Small arteries derived from the periosteum enter
the minute orifices of the compact bone (Volkmann's canals) and reach the
40
THE SKELETON
Haversian canals of the bony substance. Prolongations from these vessels
reach the marrow and communicate with branches from the nutrient artery.
The cancellous tissue is supplied by fewer but larger vessels, which are derived
from the periosteum, and which often penetrate the cortex of compact bone
and ramify in the cavities of the spongy tissue.
FIG. 7.— From a ground longitudinal section through the diaphysis of the human ulna. All canals are filled
with pigment, which is here black. Haversian canals are cut longitudinally. X 90.. (Szymonowicz.)
The medullary canal of a long bone is supplied by a large artery (sometimes
more than one) called the nutrient artery. It enters the bone by {he nutrient
foramen, which is usually near the centre of the shaft, runs in an oblique canal
through the compact structure, giving off branches to this structure, and enters
the medullary cavity, and sends branches upward and downward. These branches
communicate with branches from the periosteal vessels and subdivide into capil-
laries, which pass into comparatively large vessels. The walls of the vessels are
very thin, and in some places deficient; the venous blood enters the spaces of
the red marrow, and the current becomes extremely slow. Small veins collect
the venous blood and emerge from the bone.
In the humerus the nutrient canal is directed toward the elbow-joint; in the
radius and the ulna the nutrient canals are directed toward the elbow-joint; in
the femur, the canal is directed toward the hip-joint; and in the tibia and the
fibula, the canals are directed toward the ankle-joint. As Professor Cunningham
states it: "In the upper limb the vessels flow toward the elbow; while in the
CHEMICAL COMPOSITION OF BONE 41
lower limb they pass from the knee." The red marrow of the extremities and
the medulla of the entire shaft, and the bone of the shaft, except the circum-
ferential lamellae, are supplied by the nutrient artery. The circumferential
lamellae, wholly, and the cancellous tissue of the extremities, in part, and the
medulla of the shaft to a very small extent are supplied by vessels from the
periosteum. The extremities of a bone also receive articular arteries. In most
of the flat bones, and in some of the short bones, one or more large apertures exist
for the passage of blood-vessels to the central parts of the bone.
Veins emerge from the long bones in three places: 1. One or two large veins
accompany the nutrient artery. 2. Numerous veins emerge at the articular
extremities. 3. Many small veins arise in and emerge from compact substance.
The latter two classes do not accompany arteries. The veins in the marrow
and in the bone are devoid of valves; but immediately after emerging from the
bone they have numerous valves.
In the flat cranial bones the veins are numerous and large; as seen in diploic
canals, the walls of which are composed of osseous tissue, perforated, here and
there, for branches from adjacent cancelli. In all cancellous tissue the venous
channels are similarly arranged, and the veins have very thin coats and are
without valves. When the bone is divided, the vessels remain open; they do
not retract into their bony canals, and readily absorb any septic matter that
may be present.
The lymphatics are chiefly periosteal; but some enter the bone, along with the
vessels. Cruikshank has traced them into the substance of the bone and Klein
has described them as running in the Haversian canals. The perivascular spaces
of the Haversian canals are lymph-spaces.
Nerves, medullated (myelinic] and non-medullated (amyelinic'), are found in
bone. They are distributed freely to the periosteum, and some of the fibres ter-
minate in this structure as Pacinian corpuscles. Nerves accompany the nutrient
arteries into the interior of the bone, and also reach the marrow from the peri-
osteum by way of Volkmann's canals and the Haversian canals. They certainly
supply the arterial coats. It is not, as yet, determined whether nerves do or do
not terminate in bone-tissue. Stroh maintains that occasionally they terminate
in bone-corpuscles. According to Kolliker nerves are most numerous in the
articular extremities of the long bones, in the vertebrae, and the large flat bones.
Chemical Composition of Bone. — Bone consists of an animal and an earthy
part intimately combined.
The animal part may be obtained by immersing the bone for a considerable
time in dilute mineral acid, after which process the bone comes out exactly the
same shape as before, but perfectly flexible, so that a long bone (one of the ribs,
for example) can easily be tied into a knot. If now a transverse section is made,
the same general arrangement of the Haversian canals, lamellae, lacunae, and
canaliculi is seen, though not so plainly, as in the ordinary section.
The earthy part may be obtained separate by calcination, by which the animal
matter is completely burned out. The bone will still retain its original form, but
it will be white and brittle, will have lost about one-third of its original weight,
and will crumble with the slightest force. The earthy matter confers on bone
its hardness and rigidity, and the animal matter its tenacity.
The mineral matter consists of phosphate, carbonate, and fluoride of calcium,
chloride of sodium, and phosphate of magnesium.
The animal basis is largely composed of ossein, or fat collagen. When boiled
with water, especially under pressure, fat collagen is almost entirely resolved
into gelatin.
The organic matter of bone forms about one-third; the inorganic matter,
two-thirds. The exact composition, according to Professor Cunningham, is, of
42
THE SKELETON
organic matter, 31.04 parts; of inorganic matter, 68.97 parts. Of the earthy
matter, five-sixths is calcium phosphate. Even after the removal of all the
marrow a small percentage of fat is still found in bone.
Some of the diseases to which bones are liable mainly depend on the dispro-
portion between the two constituents of bone. Thus in the disease called rickets,
so common in the children of the poor, the bones become bent and curved, either
from the superincumbent weight of the body or under the action of certain mus-^
cles. This depends upon some defect of nutrition by which bone becomes deprived
of its normal proportion of earthy matter, while the animal matter is of unhealthy
quality. In the vertebra of a rickety subject Bostock found in 100 parts 79.75
animal and 20.25 earthy matter. Osteomalacia is a disease of adults charac-
terized by the decalcification of existing bone and by the failure in calcification
of new osteoid material. In this disease the bone shows a diminution in
inorganic and an increase in organic material. Senile atrophy renders bones
porous and brittle, and portions of bone may actually be absorbed, as is seen in
the disappearance of the alveolae in old age. In senile atrophy of the calvaria
the outer table becomes very thin, porous, and brittle, and the inner table often
becomes rough and thicker from the formation of new bone. In senile atrophy
of a long bone there is absorption of bone from the surface by osteoclasts in
Howship's lacunae, and absorption of the inner surface. The bone becomes
porous and the medulla becomes more fatty. This change is not, as was so
long taught, a decrease in organic matter
and an increase in mineral matter, but is an
actual alteration in the structure of the bone.
Ossification and Growth of Bone. — For
the early development of the skeleton the
reader is referred to text-books on embry-
ology. Embryonic connective-tissue cells of
the mesoblast develop membrane. Membrane
may become bone directly or cartilage may be
deposited, which cartilage by the process of
ossification is formed into bone. The tissue
which is eventually to become bone contains
cellular elements which evolve into osteoblasts,
or bone-forming cells. Osteoblasts exist in the
connective tissues which become bone by in-
tramembranous ossification, and in the deeper
layers of the tissue called perichondrium which
invests cartilage and which becomes the osteo-
genetic layer of the periosteum. In view of
the fact that in the total skeleton some bones
are preceded by membrane (parietal bones, frontal bone, upper part of tabular
surface of occipital bone, most of bones of the face), and others are preceded by
rods of cartilage (the long bones), two kinds of ossification are described — viz.,
the intramembranous and the intracartilaginous. Professor Cunningham says all
true bone may be correctly regarded as of membranous origin, though its appear-
ance is preceded in some instances by the deposition of cartilage ; in this case
calcification of the cartilage is an essential stage in the process of bone forma-
tion, but the ultimate conversion into true bone, with characteristic Haversian
systems, leads to the absorption and disappearance of this primitive calcified
cartilage. Intramembranous ossification forms membrane bones, that is, forms
bone directly from fibrous tissue, there being no intermediate cartilaginous
stage.
Intracartilaginous ossification consists in the ossification of cartilage.
FIG. 8. — Schematic diagram, showing epi-
physis and diaphysis and line of ossification.
Ep. Epiphysis of endochondral bone. zpt.
Zone of proliferation, zc. Zone of calcifica-
tion, ca. Cartilage. (Poirier and Charpy.)
OSSIFICATION AND GROWTH OF BONE
43
Intramembranous Ossification. — In the case of bones which are developed in
membrane no cartilaginous mould precedes the appearance of the bone-tissue.
The membrane, which occupies the place of the future bone, is of the nature of
connective tissue, and ultimately forms the periosteum. At this stage it is seen
to be composed of fibres and granular cells in a matrix. The outer portion is
more fibrous, while internally the cells or osteoblasts predominate; the whole
tissue is richly supplied with blood-vessels. At the outset of the process of bone-
formation a little network of bony spiculre is first noticed radiating from the point
or centre of ossification. When these rays of growing bone are examined with a
microscope, they are found to consist at their growing point of a network of fine,
clear fibres and granular corpuscles, with an intervening ground substance
(Fig. 9). The fibres are termed osteogenetic fibres, and are made up of fine fibrils
I'ninn of
adjacent
spicnlcs.
Osteoblasts.<
Jsteogenetic
fibres.
Calcific depdtit
between the
fibres.
Bony
spicules.
FIG. 9. — Part of the growing edge of the developing parietal bone of a foetal cat. (After J. Lawrence.)
differing little from those of white fibrous tissue. Like them, they are probably
deposited in the matrix through the influence of the cells — in this case the osteo-
blasts. The osteogenetic fibres soon assume a dark and granular appearance from
the deposition of calcareous granules in the fibres and in the intervening matrix,
and as they calcify they are found to enclose some of the granular corpuscles or
osteoblasts. By the fusion of the calcareous granules the bony tissue again assumes
a more transparent appearance, but the fibres are no longer so distinctly seen.
The involved osteoblasts form the corpuscles of the future bone, the spaces in
which they are enclosed constituting the lacuna?. As the osteogenetic fibres grow
out to the periphery they continue to calcify, and give rise to fresh bone-spicules.
Thus a network of bone is formed, the meshes of which contain the blood-vessels
and a delicate connective tissue crowded with osteoblasts. The bony trabecula?
thicken by the addition of fresh layers of bone formed by the osteoblasts on their
surface, and the meshes are correspondingly encroached upon. Subsequently
successive layers of bony tissue are deposited under the periosteum and around
the larger vascular channels, which become the Haversian canals, so that the bone
increases much in thickness.
Intracartilaginous Ossification. — Just before ossification begins the bone is
entirely cartilaginous, and in the long bone, which may be taken as an example, the
process commences in the centre and proceeds toward the extremities, which for
some time remain cartilaginous. Subsequently a similar process commences in one
44
THE SKELETON
or more places in those extremities and gradually extends through them. The
extremities do not, however, become joined to the shaft by bony tissue until growth
has ceased, but are attached to it by a layer of cartilaginous tissue termed the
epiphyseal cartilage (Fig. 8).
The first step in the ossification of the cartilage is that the cartilage-cells, at
the point where ossification is commencing and which is termed a centre of ossifica-
tion, enlarge and arrange themselves in rows (Fig. 10). The matrix in which they
are embedded increases in quantity, so that the cells become further separated
from each other. A deposit of calcareous material now takes place in this matrix,
FIG. 11. — Part of a longitudinal section of
the developing femur of a rabbit, a. Flat-
tened cartilage-cells, b. Enlarged cartilage-
cells, c, d. Newly formed bone. e. Osteo-
blasta. /. Giant-cells or osteoclasts. g, h.
Shrunken cartilage-cells. (From Atlas of His-
tology, Klein and Noble Smith.)
between the rows of cells, so that they become separated from each other by longi-
tudinal columns of calcified matrix, presenting a granular and opaque appearance.
Here and there the matrix between two cells of the same row also becomes calci-
fied, and transverse bars of calcified substance stretch across from one calcareous
column to another. Thus there are longitudinal groups of the cartilage-cells
enclosed in oblong cavities, the walls of which are formed of calcified matrix,
which cuts off all nutrition from the cells, and they, in consequence, waste, leav-
ing spaces called the primary areolae (Sharpey).
At the same time that this process is going on in the centre of the solid bar of
cartilage of which the foetal bone consists, certain changes are taking place on
OSSIFICATION AND GROWTH OF BONE
45
its surface. This is covered by a very vascular membrane, the perichondrium,
entirely similar to the embryonic connective tissue already described as constituting
the basis of membrane-bone, on the inner surface of which, that is to say, on the
surface in contact with the cartilage, are gathered the formative cells, the osteo-
blasts. By the agency of these cells a thin layer of bony tissue is being formed
between the perichondrium and the cartilage, by the intramembranous mode of
ossification just described. There are, then, in this first stage of ossification, two
processes going on simultaneously: in the centre of the cartilage the formation
of a number of oblong spaces, formed of calcified matrix and containing the
withered cartilage-cells, and on the surface of the cartilage the formation of a
layer of true membrane-bone. The second stage consists in the prolongation
into the cartilage of processes of the
deeper or osteogenetic layer of the
perichondrium, which has now be-
come periosteum (Fig. 10, ir). The
processes consist of blood-vessels and
cells — osteoblasts, or bone -formers, and
osteoclasts, or bone -destroyers. The
latter are similar to the giant-cells
(myelo-plaques) found in marrow,
and they excavate passages through
FIG. 12. — transverse section from t he femur of a
human embryo about eleven weeks old. o. A med-
ullary sinus cut transversely, and 6, another, longi-
tudinally, c. Osteoblasts. d. Newly formed osseous
substance of a lighter color, e. That of greater age.
/. Lacunce with their cells, g. A cell still united to
an osteoblast.
FIG. 13. — Vertical section from the edge of the
ossifying portion of the diaphysis of a metatar-
sal bone from a foetal calf. a. Ground-mass of
the cartilage. 6. Of the bone. c. Newly formed
bone-cells in profile, more or less embedded in in-
tercellular substance, d. Medullary canal in pro-
cess of formation, with vessels and medullary
cells. e,f. Bone-cells on their broad aspect, g.
Cartilage-capsules arranged in rows, and partly
with shrunken cell-bodies. (After Miiller.)
the new-formed bony layer by absorption, and pass through it into the cal-
cified matrix (Fig. 10). Wherever these processes come in contact with the
calcified walls of the primary areolre they absorb it, and thus cause a fusion
of the original cavities and the formation of larger spaces, which are termed
the secondary areolae (Sharpey), or medullary spaces (Miiller). In these second-
ary spaces the original cartilage-cells, having disappeared, become filled
with embryonic marrow, consisting of osteoblasts and vessels, and derived in
46
THE SKELETON
the manner described above, from the osteogenetic layer of the periosteum
(Fig. 11).
Thus far there has been traced the formation of enlarged spaces (secondary
areolae), the perforated walls of which are still formed by calcified cartilage-
matrix, containing an embryonic marrow, derived from the processes sent in
from the osteogenetic layer of the periosteum, and consisting of blood-vessels
and round-cells, osteoblasts (Fig. 11). The wails of these secondary areolae are
at this time of only inconsiderable thickness, but they become thickened by
the deposition of layers of new bone on their interior. This process takes place
in the following manner: Some of the osteoblasts of the embryonic marrow,
after undergoing rapid division, arrange themselves as an epithelioid layer on
the surface of the wall of the space (Fig. 12). This layer of osteoblasts form a
bony stratum, and thus the wall of the space becomes gradually covered with a
layer of true osseous substance. On this a second layer of osteoblasts arrange
themselves, and in their turn form an osseous layer. By the repetition of this
process the original cavity becomes very much reduced in size, and at last only
remains as a small circular hole in the centre, containing the remains of the
embryonic marrow — that is, a blood-vessel and a few osteoblasts. This small
cavity constitutes the Haversian canal of the perfectly ossified bone. The successive
layers of osseous matter which have been laid down and which encircle this central
canal constitute the lamellae of
which, as we have seen, each
Haversian system is made up.
As the successive layers of os-
teoblasts form osseous tissue,
certain of the osteoblastic cells
remain included between the
various bony layers. These
persist as the corpuscles of the
future bone, the spaces enclos-
ing them forming the lacunae
(Figs. 12 and 14). The canal-
iculi, at first extremely short, are
supposed to be extended by ab-
sorption, so as to meet those of
neighboring lacunae.
FIG. 14. — Osteoblasts from the parietal bone of a human embryo G5iir>Vi arp thp pVmncrpc; whirli
thirteen weeks old. a. Bony septa with the cells of the lacunas.
b. Layers of osteoblasts. c. The latter in transition to bone- may be observed at One partlC-
corpuscles. (After Gegenbauer.) <f . • • •«
ular point, the centre of ossifi-
cation. While they have been going on here a similar process has been set up
in the surrounding parts and has been gradually proceeding toward the end of
the shaft, so that in the ossifying bone all the changes described above may be
seen in different parts, from the true bone in the centre of the shaft to the hyaline
cartilage at the extremities. The bone thus formed differs from the bone of the
adult in being more spongy and less regularly lamellated.
Thus far, then, we have followed the steps of a process by which a solid bony
mass is produced, having vessels running into it from the periosteum, Haversian
canals in which those vessels run, medullary spaces filled with foetal marrow,
lacunae with their contained bone-cells, and canaliculi growing out of these
lacunae.
This process of ossification, however, is not the origin of the whole of the
skeleton, for even in those bones in which the ossification proceeds in a great
measure from a single centre, situated in the cartilaginous shaft of a long bone, a
considerable part of the original bone is formed by intramembranous ossification
OSSIFICATION AND GROWTH OF BONE 47
beneath the perichondrium or periosteum ; so that the girth of the bone is increased
by bony deposit from the deeper layer of this membrane. The shaft of the bone
is at first solid, but a tube is hollowed out in it by absorption around the vessels
passing into it, which becomes the medullary canal. This absorption is supposed
to be brought about by large "giant-cells," the so-called osteoclasts of Kolliker
(Fig. 11). They vary in. shape and size, and are known by containing a large
number of clear nuclei, sometimes as many as twenty. The occurrence of
similar cells in some tumors of bones has led to such tumors being denominated
"myeloid."
As more and more bone is removed by this process of absorption from the
interior of the bone to form the medullary canal, so more and more bone is
deposited on the exterior from the periosteum, until at length the bone has attained
the shape and size which it is destined to retain during adult life. As the ossifi-
cation of the cartilaginous shaft extends toward the articular ends it carries with
it, as it were, a layer of cartilage, or the cartilage grows as it ossifies, and thus the
bone is increased in length. During this period of growth the articular end, or
epiphysis, remains for some time entirely cartilaginous ; then a bony centre appears
in it, and it commences the same process of intracartilaginous ossification; but
this process never extends to any great distance. The epiphyses remain separated
from the shaft by a narrow cartilaginous layer for a definite time (Fig. 8).
This layer ultimately ossifies, the distinction between shaft and epiphysis is
obliterated, and the bone assumes its completed form and shape. The same
remarks also apply to the processes of bone which are separately ossified, such as
the trochanters of the femur. The bones, having been formed, continue to
grow until the body has acquired its full stature. They increase in length by
ossification continuing to extend in the epiphyseal cartilage, which goes on grow-
ing in advance of the ossifying process. They increase in circumference by
deposition of new bone, from the deeper layer of the periosteum, on their external
surface, and at the same time an absorption takes place within, by which the
medullary cavity is increased.
The medullary spaces which characterize the cancellous tissue are produced by
the absorption of the original foetal bone in the same way as the original medul-
lary canal is formed. The distinction between the cancellous and compact tissue
appears to depend essentially upon the extent to which this process of absorption
has been carried ; and we may perhaps remind the reader that in morbid states of
the bone inflammatory absorption produces exactly the same change, and con-
verts portions of bone naturally compact into cancellous tissue.
The number of ossific centres is different in different bones. In most of the
short bones ossification commences by a single point in the centre, and proceeds
toward the circumference. In the long bones there is a central point of ossifica-
tion for the shaft or diaphysis; and one or more for each extremity, the epiphysis.
That for the shaft is the first to appear. The union of the epiphyses with the
shaft takes place in the reverse order to that in which their ossification began, with
the exception of the fibula, and appears to be regulated by direction of the nutrient
artery of the bone. Thus the nutrient arteries of the bones of the arm and fore-
arm are directed toward the elbow, and the epiphyses of the bones forming this
joint become united to the shaft before those at the shoulder and wrist. In the
lower limb, on the other hand, the nutrient arteries pass in a direction from the
knee; that is, upward in the femur, downward in the tibia and fibula; and in
them it is observed that the upper epiphysis of the femur and the lower epiphysis
of the tibia and fibula become first united to the shaft.
Where there is only one epiphysis, the medullary artery is directed toward
that end of the bone where there is no additional centre, as toward the acromial
end of the clavicle, toward the distal end of the metacarpal bone of the thumb
48 THE SKELETON
and great toe, and toward the proximal end of the other metacarpal and meta-
tarsal bones.
Besides these epiphyses for the articular ends, there are others for projecting
parts or processes, which are formed separately from the bulk of the bone. For
an account of these the reader is referred to the description of the individual
bones in the sequel. ,
A knowledge of the exact periods when the epiphyses become joined to the
shaft is often of great importance in medico-legal inquiries. It also aids the sur-
geon in the diagnosis of many of the injuries to which the joints are liable; for it
not infrequently happens that on the application of severe force to a joint the
epiphysis becomes separated from the shaft, and such an injury may be
mistaken for a fracture or dislocation.
THE VERTEBRAL OR SPINAL COLUMN OR THE SPINE
(COLUMNA VERTEBRALIS).
The spine is a flexuous and flexible column formed of a series of bones called
vertebrae (from verier e, to turn).
The vertebrae are thirty-three in number, and have received the names cervical,
dorsal or thoracic, lumbar, sacral, and coccygeal, according to the position which
they occupy; seven being found in the cervical region, twelve in the thoracic, five
in the lumbar, five in the sacral, and four in the coccygeal.
This number is sometimes increased by an additional vertebra in one region, or
the number may be diminished in one region, the deficiency being supplied by
an additional vertebra in another. These observations do not apply to the cervical
portion of the spine, the number of bones forming which is seldom increased or
diminished.
The vertebrae in the upper three regions of the spine remain separate through-
out life, and are known as true or movable vertebrae; but those found in the
sacral and coccygeal regions are in the adult firmly united, so as to form two
bones — five entering into the formation of the upper bone or sacrum, and four into
the terminal bone of the spine or coccyx. The fused vertebrae are known as
false or immovable vertebrae.
GENERAL CHARACTERS OF A VERTEBRA.
•Each vertebra consists of two essential parts — an anterior solid segment, the
body, or centrum, and a posterior segment, the arch (arcus vertebra;), or the neural
arch. The neural arch is formed of two pedicles and two laminae, supporting
seven processes — viz., four articular, two transverse, and one spinous.
The bodies of the vertebrae are piled one upon the other, forming a strong
pillar for the support of the cranium and trunk; the arches forming a hollow
cylinder behind the bodies for the protection of the spinal cord (spinal canal or
neural canal). The different vertebrae are connected together by means of the
articular processes and the intervertebral fibrocartilages ; while the transverse
and spinous processes serve as levers for the attachment of muscles which
move the different parts of the spine. Lastly, between each pair of vertebrae
apertures exist through which the spinal nerves pass from the cord. Each of
these constituent parts must now be separately examined.
Body, or Centrum (corpus vertebra'). — The body is the largest part of a vertebra.
Above and below it is flattened; its upper and lower surfaces are rough for the
attachment of the intervertebral fibro-cartilages, and each presents a rim around
its circumference. In front it is convex from side to side, concave from above
downward. Behind it is flat from above downward and slightly concave from
THE CERVICAL VERTEBRAE 49
side to side. Its anterior surface is perforated by a few small apertures, for
the passage of nutrient vessels; while on the posterior surface is a single large,
irregular aperture, or occasionally more than one, for the exit of veins from the
body of the* vertebra — the venae basis vertebrae.
Pedicles. — The pedicles are two short, thick pieces of bone, which project
backward, one on each side, from the upper part of the body of the vertebra, at
the line of junction of its posterior and lateral surfaces. Each pedicle (radix
arcus vertebra) is a root of the vertebral arch. The concavities above and below
the pedicles are the superior and inferior intervertebral notches or grooves (incisura
vertebralis superior et inferior) ; they are four in number, two on each side, the
inferior ones being generally the deeper. When the vertebra? are articulated the
notches of each contiguous pair of bones form the intervertebral foramina (fora-
mina intervertebralia) , which communicate with the spinal canal and transmit
the spinal nerves and bloodvessels.
Laminae. — The laminae are two broad plates of bone which complete the neural
arch by fusing together in the middle line behind. They enclose a foramen, the
spinal or vertebral foramen (foramen vertebrate), which serves for the protection of
the spinal cord. When the vertebrae are joined they form, with their ligaments,
the vertebral canal (spinal or neural canal, canalis vertebralis). The lamina? are
connected to the body by means of the pedicles. Their upper and lower borders
are rough, for the attachment of the ligamenta subflava.
Processes. Spinous Process (processus spinosus). — The spinous process projects
backward from the junction of the two laminae, and serves for the attachment of
muscles and ligaments.
Articular Processes. — The articular processes (zygapophyses], four in number,
two on each side, spring from the junction of the pedicles with the laminae. Each
superior process (processus articularis superior) projects upward, its articular
surface (fades articularis superior) being directed more or less backward; each
inferior process (processus articularis inferior) projects downward, its articular
surface (fades articularis inferior) looking more or less forward.1
Transverse Processes (processus transversi). — The transverse processes, two in
number, project one at each side from the point where the lamina joins the
pedicle, between the superior and inferior articular processes. They also serve
for the attachment of muscles and ligaments.
The Cervical Vertebrae (Vertebrae Cervicales) (Fig. 15).
The cervical vertebrae are smaller than those in any other region of the spine,
and may be readily distinguished by the foramen in the transverse process, which
does not exist in the transverse process of either a dorsal or lumbar vertebra.
Body. — The body (centrum) is small, comparatively dense, and broader from
side to side than from before backward. The anterior and posterior surfaces
are flattened and of equal depth; the former is placed on a lower level than the
latter, and its inferior border is prolonged downward, so as to overlap the upper
and fore part of the vertebra below. Its upper surface is concave transversely,
and presents a projecting lip on each side; its lower surface is convex from side
to side, concave from before backward, and presents laterally a shallow concavity
which receives the corresponding projecting lip of the adjacent vertebra.
Pedicles. — The pedicles are directed outward and backward, and are
attached to the body midway between the upper and lower borders, so that
the superior intervertebral notch is as deep as the inferior, but it is, at the same
time, narrower.
1 It may, perhaps, be as well to remind the reader that the direction of a surface is determined by that of a
line drawn at right angles to it. — ED. of 15th English Edition.
50
THE SKELETON
Laminae. — The laminae are narrow, long, thinner above than below, and
overlap each other, enclosing the spinal foramen, which is very large, and of a
triangular form.
Processes. Spinous Process. — The spinous process is short, and bifid at the
extremity, to afford greater extent of surface for the attachment of muscles, the
two divisions being often of unequal size. They increase in length from the fourth
to the seventh vertebra.
Anterior tubercle of trans-
verse process.
Costo-transverse foramen for
vertebral artery and vein and
sympathetic plexus.^
Posterior tubercle, of
transverse process.
Costal cartilage.
Transverse process.
^-Superior articular
process.
Inferior articular process.
FIG. 15. — Cervical vertebra.
Articular Processes. — The articular processes are flat, oblique, and of an oval
form: the superior are directed backward and upward; the inferior forward and
downward.
Transverse Processes. — The transverse processes are short, directed down-
ward, outward, and forward, bifid at their extremity, and marked by a
groove along their upper surface, which runs downward and outward from the
superior intervertebral notch and serves for the transmission of one of the cer-
vical nerves. They are situated in front of the articular processes and on the
outer side of the pedicles. The transverse processes are pierced at their base by
a foramen, for the transmission of the vertebral artery, vein, and a plexus of
sympathetic nerves. This foramen is known as the transverse foramen, the costo-
transverse foramen, and the vertebrarterial foramen (foramen transversarium) .
Each process is formed by two roots: the anterior root, sometimes called the
costal process, arising from the side of the body, and the homologue of the rib
in the thoracic region of the spine; the posterior root springs from the junction of
the pedicle with the lamina, and corresponds with the transverse process in the
thoracic region. It is by the junction of the two that the foramen for the vertebral
vessels is formed. The extremity of each of the anterior roots forms the anterior
tubercle (tuberculum anterius) and the extremity of each of the posterior roots the
posterior tubercle (tubercidum posterius) of the transverse processes.1
The peculiar vertebrae in the cervical regions are the first, or atlas; the second,
or axis; and the seventh, or vertebra prominens. The great modifications in the
form of the atlas and axis are designed to admit of the nodding and rotatory
movements of the head.
Atlas. — The atlas (Fig. 16) is so named from supporting the globe of the head.
The chief peculiarities of this bone are that it has neither body nor spinous process.
The body is detached from the rest of the bone, and forms the odontoid process of
1 The anterior tubercle of the transverse process of the sixth cervical vertebra is of large size, and is some-
times known as "Chassaignac's" or the "carotid tubercle" (tuberculum caroticum). It is in close relation with
the carotid artery, which lies in front and a little external to it; so that, as was first pointed out by Chassaignac,
the vessel can with ease be compressed against it. — ED. of 15th English Edition.
THE CERVICAL VERTEBRAE
51
the second vertebra; while the parts corresponding to the pedicles join in front to
form the anterior arch. The atlas is ring-like, and consists of an anterior arch, a
posterior arch, and two lateral masses. The anterior arch (arcus anterior) forms about
one-fifth of the ring; its anterior surface is convex, and presents about its centre a
tubercle (tuberculum anterius), for the attachment of the Longus colli muscle; pos-
teriorly it is concave, and marked by a smooth, oval facet, called the circular facet
(fovea dentis), covered with cartilage, for articulation with the odontoid process of the
Tubercle.
Transverse
process.
Diagram of section of odontoid
process.
Diagram of section of
transverse ligament.
Foramen for
vertebral artery.
Groove for vertebral artery
and 1st cervical nerve.
Rudimentary spinous process. .
FIG. 16.— First cervical vertebra, or atlas.
axis. The upper and lower borders give attachment to the anterior occipito-atlantal
and the anterior atlanto-axial ligaments, which connect it with the occipital bone
above and the axis below. The posterior arch (arcus posterior) forms about two-
fifths of the circumference of the bone; it terminates behind in a tubercle (tuber-
culum posterius) , which is the rudiment of a spinous process, and gives origin to
the Rectus capitis posticus minor. The diminutive size of this process prevents
any interference in the movements between the atlas and the cranium. The pos-
terior part of the arch presents above and behind a rounded edge for the attach-
ment of the posterior occipito-atlantal ligament, while in front, immediately
behind each superior articular process, is a groove (sulcus arteries vertebralis] ,
sometimes converted into a foramen by a delicate bony spiculum, which arches
backward from the posterior extremity of the superior articular process. These
grooves represent the superior intervertebral notches, and are peculiar from being
situated behind the articular processes, instead of in front of them, as in the
other vertebrae. They serve for the transmission of the vertebral artery, which,
ascending through the foramen in the transverse process, winds round the lateral
mass in a direction backward and inward. They also transmit the suboccipital
(first spinal) nerve. On the under surface of the posterior arch, in the same
situation, are two other grooves, placed behind the lateral masses, and repre-
senting the inferior intervertebral notches of other vertebrae. They are much
less marked than the superior. The lower border also gives attachment to the
posterior atlanto-axial ligament, which connects it with the axis. The lateral
masses (masses laterales) are the most bulky and solid parts of the atlas, in order
to support the weight of the head; they present two articulating surfaces above,
and two below. Each superior process (fovea articularis superior) is of large size,
oval, concave, and approaches its companion in front, but diverges from it
behind; it is directed upward, inward, and a little backward, forming a kind of
cup for the corresponding condyle of the occipital bone. The two processes are
admirably adapted to the nodding movements of the head. Not infrequently
they are partially subdivided by a more or less deep indentation, which encroaches
upon each lateral margin. Each inferior articular process (fades articularis inferior)
52 THE SKELETON
is circular in form, flattened or slightly concave, and directed downward and
inward, articulating with the axis. The inferior processes permit the rotatory
movements. Just below the inner margin of each superior articular surface is
a small tubercle, for the attachment of the transverse ligament, which, stretching
across the ring of the atlas, divides it into two unequal parts or arches; the anterior
or smaller segment receiving the odontoid process of the axis, the posterior allow-
ing the transmission of the spinal cord and its membranes. This part of the
spinal canal is of considerable size, to afford space for the spinal cord ; and hence
lateral displacement of the atlas may occur without compression of this structure.
The transverse processes are of large size, project directly outward and down-
ward from the lateral masses, and serve for the attachment of special muscles
which assist in rotating the head. They are long, not bifid, and perforated at
their base by a canal for the vertebral artery, which is directed from below,
upward, and backward.
Odontoid process.
Rough surface for check ligaments. —
_Articular surface for
atlas.
Articular surface for transverse ligament. .
Spinous process.-!
mrunr- •^p, _
i Transverse process.
i
Inferior articular process.
FIG. 17. — Second cervical vertebra, or axis.
Axis. — The axis (epistropheus) (Fig. 17) is the pivot upon which the first
vertebra, carrying the head, rotates, hence the name, axis. The most distinctive
character of this bone is the strong, prominent process, tooth-like in form (hence
the name odontoid process, or dens), which rises perpendicularly from the upper
surface of the body. The body is deeper in front than behind, and prolonged
downward anteriorly so as to overlap the upper and fore part of the next
vertebra. It presents in front a median longitudinal ridge, separating two
lateral depressions, for the attachment of the Longus colli muscle of either side.
The odontoid process presents two articulating surfaces covered with cartilage:
one in front, of an oval form, for articulation with the atlas (fades articularis
anterior) ; another behind (fades articularis posterior), for the transverse ligament
— the latter frequently encroaching on the sides of . the process. The apex is
pointed, and gives attachment to the middle odontoid ligament (ligamentum
apids dentis). Below the apex the process is somewhat enlarged, and presents
on either side a rough impression for the attachment of the lateral fasciculi of
the odontoid or check ligaments, which connect it to the occipital bone; the base
of the process, where it is attached to the body, is constricted, so as to prevent
displacement from the transverse ligament, which binds it in this situation to the
anterior arch of the atlas. Sometimes, however, this process does become dis-
placed, especially in children, in whqm the ligaments are more relaxed: instant
death is the result of this accident. The internal structure of the odontoid process
is more compact than that of the body. The pedicles are broad and strong, espe-
cially their anterior extremities, which coalesce with the sides of the body and the
THE THORACIC OR DORSAL VERTEBRA
53
root of the odontoid process. The laminae are thick and strong, and the spinal
foramen large, but smaller than that of the atlas. The transverse processes are very
small, not bifid, and each is perforated by the foramen for the vertebral artery,
which is directed obliquely upward and outward. The superior articular surfaces
(fades articulares superiores) are round, slightly convex, directed upward and
outward, and are peculiar in being supported on the body, pedicles, and trans-
verse processes. The inferior
articular surfaces (fades articu- Body,
lares inferior es) have the same
direction as those of the other
cervical vertebra3. The superior
intervertebral notches are very
shallow, and lie behind the artic-
ular processes ; the inferior in
front of them, as in the other
cervical vertebrae. The spinous
process is of large size, very
strong, deeply channelled on its
under surface, and presents a
bifid, tubercular extremity for
the attachment of muscles which
serve to rotate the head upon
the spine.
Seventh Cervical (Fig. 18).—
The most distinctive character
of this vertebra is the existence
of a very long and prominent
spinous process; hence the name vertebra prominens. This process is thick, nearly
horizontal in direction, not bifurcated, and has attached to it the lower end of the
ligamentum nuchae. The transverse process is usually of large size, its posterior
tubercles are large and prominent, while the anterior are small and faintly marked ;
its upper surface has usually a hollow groove, and it seldom presents more than a
trace of bifurcation at its extremity. The foramen in the transverse process is
sometimes as large as in the other cervical vertebrae, but is usually smaller on one
or both sides, and is sometimes wanting. On the left side it occasionally gives
passage to the vertebral artery; more frequently the vertebral vein traverses it on
both sides; but the usual arrangement is for both artery and vein to pass in front
of the transverse process, and not through the foramen. Occasionally the anterior
root of the transverse process exists as a separate bone, and attains a large size.
It is then known as a cervical rib.
Spinous process.
FIG. 18. — Seventh cervical vertebra, or vertebra prominens.
The Thoracic or Dorsal Vertebrae (Vertebrae Thoracales).
The thoracic vertebrae are intermediate in size between those in the cervical and
those in the lumbar region, and increase in size from above downward, the upper
vertebra? in this segment of the spine being much smaller than those in the
lower part of the region. A thoracic vertebra may be at once recognized by the
presence on each side of the body of one or more facets or half-facets for the heads
of the ribs.
Bodies. — The bodies of the thoracic vertebra? resemble those in the cervical and
lumbar regions at the respective ends of this portion of the spine; but in the middle
of the thoracic region their form is very characteristic, being heart-shaped , and as
broad in the antero-posterior as in the lateral direction. They are thicker behind
than in front, flat above and below, convex and prominent in front, deeply con-
54
THE SKELETON
cave behind, slightly constricted in front and at the sides, and marked on each
side, near the root of the pedicle, by two demi-facets, one above, the other below
(fovea costalis superior et inferior). These are covered with cartilage in the recent
state, and, when articulated with the adjoining vertebrae, form, with the inter-
vening fibro-cartilage, oval surfaces for the reception of the heads of the corre-
sponding ribs. The tenth, eleventh, and twelfth thoracic vertebrae each possesses
one complete facet for the head of the rib, instead of two demi-facets.
Superior articular process.
Demi-facet for head of rib.
Facet for tubercle of rib.
Demi-facet for head of rib.
Inferior articular process.
FIG. 19. — A thoracic vertebra.
Pedicles. — The pedicles are directed backward, and the inferior intervertebral
notches are of large size, and deeper than in any other region of the spine.
Laminae. — The laminae are broad, thick, and imbricated — that is to say, over-
lapping one another like tiles on a roof. The spinal foramen is small, and of a
circular form.
Processes. Spinous Processes. — Each spinous process is long, triangular on
transverse section, directed obliquely downward, and terminates in a tubercular
extremity. They overlap one another from the fifth to the eighth vertebra, but
are less oblique in direction above and below.
Articular Processes. — The articular processes are flat, nearly vertical in
direction, and project from the upper and lower part of the pedicles; the
superior being directed backward and slightly outward and upward, the inferior
forward and a little inward and downward.
Transverse Processes. — The transverse processes arise from the same parts
of the arch as the posterior roots of the transverse processes in the neck, and
are situated behind the articular processes and pedicles; they are thick, strong,
and of great length, directed obliquely backward and outward, presenting a
clubbed extremity, which is tipped on its anterior part by a small concave surface,
for articulation with the tubercle of a rib (fovea costalis transversalis] . The
twelfth, the eleventh, and sometimes the tenth thoracic vertebra has no facet on
the transverse process. Besides the articular facet for the rib, three indistinct
tubercles may be seen arising from the transverse processes: one at the upper
border, one at the lower border, and one externally. In man they are compara-
tively of small size, and serve only for the attachment of muscles. But in some
animals they attain considerable magnitude, either for the purpose of more closely
THE THORACIC VERTEBRAE
55
connecting the segments of this portion of the spine or for muscular and liga-
mentous attachment.
The peculiar thoracic vertebrae are the first, ninth, tenth, eleventh, and twelfth
(Fig. 20).
f An entire facet above;
\ a demi-facet below.
'-A demi-facet above.
— One entire facet.
( An entire facet.
J No facet on transverse
process, which is ru-
|_ dimentary.
An entire facet.
(No facet on trans-
verse process.
Inferior articular
process, convex
and turned out-
ward.
FIG. 20. — Peculiar thoracic vertebrae.
First Thoracic Vertebra. — The first thoracic vertebra presents, on each side of
the body, a single entire articular facet for the head of the first rib and a half-
facet for the upper half of the second. The body is like that of a cervical vertebra,
being broad transversely, its upper surface is concave, and lipped on each side.
The articular surfaces are oblique, and the spinous process thick, long, and almost
horizontal.
Ninth Thoracic Vertebra. — The ninth thoracic vertebra has no demi-facet
below. In some subjects, however, the ninth has two demi-facets on each side;
when this occurs the tenth has only a demi-facet at the upper part.
56 THE SKELETON
Tenth Thoracic Vertebra. — The tenth thoracic vertebra has (except in the
cases just mentioned) an entire articular facet on each side, above, which is
partly placed on the outer surface of the pedicle. It has no demi-facet below.
Eleventh Thoracic Vertebra. — In the eleventh thoracic vertebra the body ap-
proaches in its form and size to the lumbar. The articular facets for the heads
of the ribs, one on each side, are of large size, and placed chiefly on the pedicles,
which are thicker and stronger in this and the next vertebra than in any other
part of the thoracic region. The spinous process is short, and nearly horizontal
in direction. The transverse processes are very short, tubercular at their extrem-
ities, and have no articular facets for the tubercles of the ribs.
Twelfth Thoracic Vertebra. — The twelfth thoracic vertebra has the same
general characters as the eleventh, but may be distinguished from it by the in-
ferior articular processes, being convex and turned outward, like those of the
lumbar vertebrae; by the general form of the body, laminae, and spinous process,
approaching to that of the lumbar vertebrae; and by the transverse processes
being shorter, and marked by three elevations, the superior, inferior, and external
tubercles, which correspond to the mammillary, accessory, and transverse pro-
cesses of the lumbar vertebrae. Traces of similar elevations are usually to be found
upon the other thoracic vertebrae (vide ut supra).
The Lumbar Vertebrae (Vertebrae Lumbales) (Fig. 21).
The lumbar vertebrae are the largest segments of the vertebral column, and can
at once be distinguished by the absence of the foramen in the transverse process,
the characteristic point of the cervical vertebrae, and by the absence of any articu-
lating facet on the side of the body, the distinguishing mark of the thoracic
vertebrae.
Superior articular process
FIG. 21. — Lumbar vertebra.
Body. — The body is large, and has a greater diameter from side to side than
from before backward, slightly thicker in front than behind, flattened or slightly
concave above and below, concave behind, and deeply constricted in front and at
the sides, presenting prominent margins, which afford a broad basis for the sup-
port of the superincumbent weight.
Pedicles. — The pedicles are very strong, directed backward from the upper
part of the bodies; consequently, the inferior intervertebral notches are of con-
siderable depth.
Laminae.— The laminae are broad, short, and strong, and the spinal fora-
men triangular, larger than in the thoracic, smaller than in the cervical, region.
THE LUMBAR VERTEBRAE 57
Processes. Spinous Processes. — The spinous processes are thick and broad,
somewhat quadrilateral, horizontal in direction, thicker below than above, and
terminating by a rough, uneven border.
Articular Processes. — The superior articular processes are concave, and look
backward and inward; the inferior are convex, and look forward and outward;
the former are separated by a much wider interval than the latter, embracing
the lower articulating processes of the vertebra above.
Transverse Processes. — The transverse processes are long, slender, directed
transversely outward in the upper three lumbar vertebrae, slanting a little upward
in the lower two. They are situated in front of the articular processes, instead
of behind them, as in the thoracic vertebrae, and are homologous with the ribs. Of
the three tubercles noticed in connection with the transverse processes of the
twelfth thoracic vertebra, the superior one on each side becomes connected in this
region with the back part of the superior articular process, and has received the
Inf. articular process.
/
Costal process. ^ .- '^L^^ Mammillary process.
Accessory process.
Sup. articular process.
FIG. 22. — Lumbar vertebra.
name of mammillary process (processus mammillaris) ; the inferior is represented
by a small process pointing downward, situated at the back part of the base of
the transverse process, and called the accessory process (processus accessorius):
these are the true transverse processes, which are rudimental in this region of
the spine. The external one is the so-called transverse process, the homologue
of the rib, and hence sometimes called the costal process (processus costarius)
(Fig. 22). Although in man the costal processes are comparatively small, in some
animals they attain considerable size, and serve to lock the vertebrae more
closely together.
Fifth Lumbar Vertebra. — The fifth lumbar vertebra is characterized by having
the body much thicker in front than behind, which accords with the prominence
of the sacro- vertebral articulation; by the smaller size of its spinous process; by
the wide interval between the inferior articulating processes; and by the greater
size and thickness of its transverse processes, which spring from the body as well
as from the pedicles.
58
THE SKELETON
Structure of the Vertebrae. — The body is composed of light, spongy, cancel-
Ions tissue, having a thin coating of compact tissue on its external surface per-
forated by numerous orifices, some of large size, for the passage of vessels; its
interior is traversed by one or two large canals, for the reception of veins, which
converge toward a single large, irregular aperture or several small apertures at the
posterior part of the body of each bone. The arch and processes projecting from
it have, on the contrary, an exceedingly thick covering of compact tissue (Fig. 23).
FIG 23. — Bony structure of a lumbar vertebra. (Poirier and Charpy.)
Development-. — Each vertebra is formed of four primary centres of ossification
(Fig. 24), one for each lamina and its processes, and two for the body.1 Ossifica-
tion commences in the lamina; about the sixth week of foetal life, in the situation
where the transverse processes afterward project, the ossific granules shooting
backward to the spine, forward into the pedicles, and outward into the transverse
and articular processes. Ossification in the body commences in the middle of
the cartilage about the eighth week by two closely approximated centres, which
By 4 primary centres.
\2for body (8th week).
1 for each trans-
verse process,
16 years.
Ifor each lamina (6th week).
FIG. 24. — Development of a vertebra.
By 2 additional plates.
)-•! for upper surface
of body,
1 for under surface
of body,
FIG. 25.
21 years.
2 (sometimes 1) for spinous process (16 years).
FIG. 26.
speedily coalesce to form one central ossific point. According to some authors,
ossification commences in the lamina? only in the upper vertebrae — i. e., in the
cervical and upper thoracic. The first ossific points in the lower vertebra? are those
which are to form the body, the osseous centres for the lamina; appearing at a
subsequent period. At birth these three pieces are perfectly separate. During
the first year the lamina? become united behind, the union taking place first in
the lumbar region and then extending upward through the thoracic and lower cer-
vical regions. About the third year the body is joined to the arch on each side in
such a manner that the body is formed from the three original centres of ossifica-
1 By many observers it is asserted that the bodies of the vertebra are developed from a single centre which
speedily becomes bilobed, so as to give the appearance of two nuclei ; but that there are two centres, at all events
sometimes, is evidenced by the fact that the two halves of the body of the vertebra may remain distinct through-
out life and be separated by a fissure through which a protrusion of the spinal membrane may take place, con-
stituting an anterior spina bifida. — ED. of the 15th English Edition.
THE LUMBAR VERTEBRA
59
By S centres.
"or anterior arch (1st year),
not constant.
tion, the amount contributed by the pedicles increasing in extent from below
upward. Thus the bodies of the sacral vertebrae are formed almost entirely from
the central nuclei ; the bodies of the lumbar are formed laterally and behind by the
pedicles ; in the thoracic region the pedicles advance as far forward as the articular
depressions for the head of the ribs, forming these cavities of reception; and in
the neck the lateral portions of the bodies are formed entirely by the advance of
the pedicles. The line along which union takes place between the body and the
neural arch is named neuro-central suture. Before puberty no other changes occur,
excepting a gradual increase in the growth of these primary centres; the upper
and under surfaces of the bodies and the ends of the transverse and spinous pro-
cesses being tipped with cartilage, in which ossific granules are not as yet deposited.
At sixteen years (Fig. 26) three secondary centres appear, one for the tip of
each transverse process, and one for the extremity of the spinous process. In
some of the lumbar vertebra?, especially the first, second, and third, a second
ossifying centre appears at the base of the spinous process. At twenty-one years
(Fig. 25) a thin, circular, epiphyseal plate of bone is formed in the layer of cartilage
situated on the upper and under surfaces of the body, the former being the thicker
of the two. All these become joined, and the bone is completely formed between
the twenty-fifth and thirtieth year of life.
Exceptions to this mode of development occur in the first, second, and seventh
cervical, and in the vertebra? of the lumbar region.
Atlas (Fig. 27). — The number of centres of ossification of the atlas is very vari-
able. It may be developed from two, three, four, or five centres. The most
frequent arrangement is by three
centres. Two of these are destined
for the two lateral or neural masses,
the ossification of which commences
about the seventh week near the
articular processes, and extend
backward; these portions of bone
are separated from one another be-
hind, at birth, by a narrow interval
filled in with cartilage. Between
the third and fourth years they unite
either directly or through the me-
dium of a separate centre developed
in the cartilage in the middle line.
The anterior arch, at birth, is al-
together cartilaginous, and in this
a separate nucleus appears about
the end of the first year after birth,
and, extending laterally, joins the
neural processes in front of the pedi-
cles. Sometimes there are two nu-
clei developed in the cartilage, one
on either side of the median line,
which join to form a single mass.
And occasionally there is no sepa-
rate centre, but the anterior arch is formed by the gradual extension forward
and ultimate junction of the two neural processes.
Axis. — The axis (Fig. 28) is developed by seven centres. The body and arch
of this bone are formed in the same manner as the corresponding parts in the other
vertebrae: one centre (or two, which speedily coalesce) for the lower part of the
body, and one for each lamina. The centres for the laminae appear about the
FIG. 27.— Atlas.
By 7 centres.
2d year.
6th month.
1 for each lateral mass.
- — 1 for body (4th month).
1 for under surface of
body.
FIG. 28.— Axis.
S additional centres.
for tubercles on superior articular process.
FIG. 29. — Lumbar vertebra.
60 THE SKELETON
seventh or eighth week, that for the body about the fourth month. The odontoid
process consists originally of an extension upward of the cartilaginous mass in
which the lower part of the body is formed. At about the sixth month of foetal
life two osseous nuclei make their appearance in the base of this process; they
are placed laterally, and join before birth to form a conical bilobed mass deeply
cleft above; the interval between the cleft and the summit of the process is formed
by a wedge-shaped piece of cartilage, the base of the process being separated
from the body by a cartilaginous interval, which gradually becomes ossified at
its circumference, but remains cartilaginous in its centre until advanced age.1
Finally, as Humphry has demonstrated, the apex of the odontoid process has
a separate nucleus, which appears in the second year and joins about the twelfth
year. In addition to these there is a secondary centre for a thin epiphysial plate
on the under surface of the body of the bone. J. Bland Sutton and others main-
tain that the odontoid process is the "dissociated body of the atlas."2
Seventh Cervical. — The anterior or costal part of the transverse process of the
seventh cervical is developed from a separate osseous centre at about the sixth
month of foetal life, and joins the body and posterior division of the transverse
process between the fifth and sixth years. Sometimes this process continues as
a separate piece, and, becoming lengthened outward, constitutes what is known
as a cervical rib. This separate ossific centre for the costal process has also been
found in the fourth, fifth, and sixth cervical vertebrae.
Lumbar Vertebrae. — The lumbar vertebra (Fig. 29) have two additional centres
(besides those peculiar to the vertebrae generally) for the mammillary tubercles,
which project from the back part of the superior articular processes. The trans-
verse process of the first lumbar is sometimes developed as a separate piece, which
may remain permanently unconnected with the remaining portion of the bone,
thus forming a lumbar rib — a peculiarity that is rarely met with.
Progress of Ossification in the Spine Generally. — Ossification of the laminae of
the vertebras commences in the cervical region of the spine, and proceeds gradually
downward. Ossification of the bodies, on the other hand, commences a little
below the centre of the spinal column (about the ninth or tenth thoracic vertebra),
and extends both upward and downward. Although the ossific nuclei make their
first appearance in the lower thoracic vertebrae, the lumbar and first sacral ver-
tebras are those in which these nuclei are largest at birth.
Attachment of Muscles. — To the Atlas are attached nine pairs: the Longus
colli, Rectus capitis anticus minor, Rectus lateralis., Obliquus capitis superior and
inferior, Splenius colli, Levator anguli scapulae, First Intertransverse, and Rectus
capitis posticus minor.
To the Axis are attached eleven pairs: the Longus colli, Levator anguli scapulae,
Splenius colli, Scalenus medius, Transversalis colli, Intertransversales, Obliquus
capitis inferior, Rectus capitis posticus major, Semispinalis colli, Multifidus spinae,
Interspinales.
To the remaining vertebrae, generally, are attached thirty-five pairs and a
single muscle: anteriorly, the Rectus capitis anticus major, Longus colli, Scalenus
anticus medius and posticus, Psoas magnus and parvus, Quadratus lumborum,
Diaphragm, Obliquus abdominis internus, and Transversalis abdominis; pos-
teriorly, the Trapezius, Latissimus dorsi, Levator anguli scapulae, Rhomboideus
major and minor, Serratus posticus superior and inferior, Splenius, Erector spinae,
Ilio-costalis, Longissimus dorsi, Spinalis dorsi, Cervicalis ascendens, Transversalis
colli, Trachelo-mastoid, Complexus, Biventer cervicis, Semispinalis dorsi and colli,
Multifidus spinae, Rotatores spinae, Interspinales, Supraspinales, Intertransversales,
Levatores costarum.
1 See Cunningham, Jour. Anat., vol. xx. p. 238. — ED. of the 15th English Edition.
2 Ligaments: their Nature and Morphology.
THE SACRAL AND COCCYGEAL VERTEBRAE
The Sacral and Coccygeal Vertebrae (False or Immovable Vertebrae).
61
The sacral and coccygeal vertebrae consist, at an early period of life, of nine
separate pieces, which are united in the aduli so as to form two bones, five enter-
ing into the formation of the sacrum, four into that of the coccyx. Occasionally,
the coccyx consists of five bones.1
Sacrum (os sacrum). — The os sacrum (sacer, sacred), the sacred bone.
So called, according to some, because it was the part selected in sacrifices.
Another view is that the name is derived from an opinion of the Jewish rabbis,
that this part of the skeleton strongly resists decay and becomes the germ from
which the new body will be raised. The sacrum is a large, triangular bone (Fig.
30), situated at the lower part of the vertebral column, and at the upper and
back part of the pelvic cavity, where it is inserted like a wedge between the two
innominate bones; its upper part or base articulating with the last lumbar ver-
tebra, its apex with the coccyx. It is composed of five segments of bone (sacral
vertebrae, or vertebra sacrales}. The sacrum is curved upon itself, and placed
very obliquely, its upper extremity projecting forward, and forming, with the
last lumbar vertebra, a very prominent angle, called the promontory (promontorium) ,
or sacro-vertebral angle; while its central part is directed backward, so as to give
increased capacity to the pelvic cavity. It presents for examination an anterior and
posterior surface, two lateral surfaces, a base, an apex, and a central canal.
FIG. 30.— Sacrum, anterior surface.
Surfaces. Anterior or Pelvic Surface (fades pelvina). — The anterior surface
is concave from above downward, and slightly so from side to side. In the
middle are seen four transverse ridges (lineoe transversce) , indicating the original
division of the bone into five separate pieces. The portions of bone intervening
1 Sir George Humphry describes this as the usual composition of the coccyx. On the Skeleton, p. 456.
62
THE SKELETON
between the ridges correspond to the bodies of the vertebrae. The body of the first
segment is of large size, and in form resembles that of a lumbar vertebra; the suc-
ceeding ones diminish in size from above downward, are flattened from before
backward, and curved so as to accommodate themselves to the form of the sacrum,
being concave in front, convex behind. At each end of the ridges above men-
tioned are seen the anterior sacral foramina (foramina sacralia anteriora), analogous
to the intervertebral foramina, four in number on each side, somewhat rounded
in form, diminishing in size from above downward, and directed outward and
forward; they transmit the anterior branches of the sacral nerves and the lateral
sacral arteries. External to these foramina is the lateral mass (pars lateralis),
consisting at an early period of life of separate segments; these become blended,
in the adult, with the bodies, with each
other, and with the posterior transverse
processes. Each lateral mass is traversed
by four broad, shallow grooves, which
lodge the anterior sacral nerves as they
pass outward, the grooves being sepa-
rated by prominent ridges of bone, which
give attachment to the slips of the
Pyriformis muscle.
If a vertical section is made through
the centre of the sacrum (Fig. 31), the
bodies are seen to be united at their cir-
cumference by bone, a wide interval being
left centrally, which, in the recent state,
is filled by intervertebral substance. In
some bones this union is more complete
between the lower segments than between
the upper ones.
Posterior or Dorsal Surface (fades dor-
salis) . — The posterior surface (Fig. 32) is
convex and much narrower than the ante-
rior. In the middle line are three or four
tubercles, which represent the rudimen-
tary spinous processes of the sacral verte-
brae. Of these tubercles, the first is
usually prominent, and perfectly distinct
from the rest; the second and third are
either separate or united into a tubercular
ridge (crista sacralis media], which dimin-
ishes in size from above downward; the
fourth usually, and the fifth always,
remaining undeveloped. The gap which results from failure of the laminae to
meet in the mid-line is called the hiatus sacralis. External to the spinous pro-
cesses on each side are the laminae, broad and well marked in the first three
pieces; sometimes the fourth, and generally the fifth, are only partially developed
and fail to meet in the middle line. These partially developed laminae are prolonged
downward as rounded processes, the sacral cornua (cornua sacralia), and are con-
nected to the cornua of the coccyx. Between them the bony wall of the lower end
of the sacral canal is imperfect. External to the laminae is a linear series of
indistinct tubercles representing the articular processes (cristce sacrales articulares) ;
the upper pair are large, well developed, and correspond in shape and direction
to the superior articulating processes of a lumbar vertebra; the second and third
are small; the fourth and fifth (usually blended together) are situated on each
FIG. 31. — Vertical section of the sacrum.
THE SACRAL AND COCCYQEAL VERTEBRA
63
side of the sacral canal and assist in forming the sacral cornua. External to the
articular processes are the four posterior sacral foramina (foramina sacralia pos-
teriora); they are smaller in size and less regular in form than the anterior,
and transmit the posterior branches of the sacral nerves. On the outer side of
Erector spime.
Latissimus dorsi.
Erector spiwe.
_ Upper half of fifth
posterior sacral foramen.
FIG. 32. — Sacrum, posterior surface.
the posterior sacral foramina is a series of tubercles, the rudimentary transverse
processes of the sacral vertebrae (cristce sacrales laterales] . The first pair of trans-
verse tubercles are large, very distinct, and correspond with each superior angle of
the bone; they together with the second pair, which are of small size, give attach-
ment to the horizontal part of the sacro-iliac ligament; the third gives attachment
to the oblique fasciculi of the posterior sacro-iliac ligaments ; and the fourth
and fifth to the great sacro-sciatic ligaments. The interspace between the spinous
and transverse processes on the back of the sacrum presents a wide, shallow
concavity, called the sacral groove: it is continuous above with the vertebral
groove, and lodges the origin of the Multifidus spinae.
Lateral Surface. — The lateral surface, broad above, becomes narrowed into a
thin edge below. Its upper half presents in front a broad, ear-shaped surface for
articulation with the ilium. This is called the auricular surface (fades auricularis) ,
and in the fresh state is coated with fibro-cartilage. It is bounded posteriorly by
deep and uneven impressions, for the attachment of the posterior sacro-iliac liga-
ments. The chief prominence is called the tuberosity (tuberositas sacralis) . The
lower half is thin and sharp, and terminates in a projection called the inferior lateral
angle; below this angle is a notch, which is converted into a foramen by articula-
tion with the transverse process of the upper piece of the coccyx, and transmits
the anterior division of the fifth sacral nerve. This lower, sharp border gives
attachment to the greater and lesser sacro-sciatic ligaments, and to some fibres
of the Glutens maximus posteriorly, and to the Coccygeus in front.
64 THE SKELETON
Base (basis oss. sacri). — The base of the sacrum, which is broad and expanded, is
directed upward and forward. In the middle is seen a large oval articular surface,
which is connected with the under surface of the body of the last lumbar vertebra
by a fibre-cartilaginous disk. It is bounded behind by the large, triangular orifice
of the sacral canal. The orifice is formed behind by the laminae and spinous process
of the first sacral vertebra: the superior articular processes project from it on each
side; they are oval, concave, directed backward and inward, like the superior
articular processes of a lumbar vertebra; and in front of each articular process i§
an intervertebral notch, which forms the lower part of the foramen between the
last lumbar and first sacral vertebra. Lastly, on each side of the large oval articular
plate is a broad and flat triangular surface of bone, which extends outward,
supports the Psoas magnus muscle and lumbo-sacral cord, and is continuous
on each side with the iliac fossa. This is called the ala of the sacrum (ala
sacralis) , and gives attachment to a few of the fibres of the Iliacus muscle. The
posterior part of the ala represents the transverse process of the first sacral
segment.
Apex (apex oss. sacri). — The apex, directed downward and slightly forward,
presents a small, oval, concave surface for articulation with the coccyx.
Spinal Canal. — The spinal canal in this region is called the sacral canal (canalis
sacralis). It runs throughout the greater part of the bone; it is large and tri-
angular in form above, small and flattened, from before backward, below. In
this situation its posterior wall is incomplete, from the • non-development of the
laminae and spinous processes (hiatus sacralis). It lodges the sacral nerves,
and is perforated by the anterior and posterior sacral foramina, through which
these pass out.
Structure. — It consists of much loose, spongy tissue within, invested externally
by a thin layer of compact tissue.
Differences in the Sacrum of the Male and Female. — The sacrum in the
female is shorter and wider than in the male; the lower half forms a greater
angle with the upper, the upper half of the bone being nearly straight, the lower
half presenting the greatest amount of curvature. The bone is also directed more
obliquely backward, which increases the size of the pelvic cavity; but the sacro-
vertebral angle projects less. In the male the curvature is more evenly dis-
tributed over the whole length of the bone, and is altogether greater than in
the female.
Peculiarities of the Sacrum. — This bone, in some cases, consists of six pieces;
occasionally, the number is reduced to four. Sometimes the bodies of the first
and second segments are not joined or the laminae and spinous processes have not
coalesced. Occasionally, the upper pair of transverse tubercles are not joined to
the rest of the bone on one or both sides; and, lastly, the sacral canal may be open
for nearly the lower half of the bone, in consequence of the imperfect development
of the laminae and spinous processes. The sacrum, also, varies considerably with
respect to its degree of curvature. From the examination of a large number of
skeletons it would appear that in one set of cases the anterior surface of this bone
was nearly straight, the curvature, which was very slight, affecting only its lower
end. In another set of cases the bone was curved throughout its whole length,
but especially toward its middle. In a third set the degree of curvature was less
marked, and affected especially the lower third of the bone.
Development (Fig. 33). — The sacrum, formed by the union of five vertebrae,
has thirty-five centres of ossification.
The bodies of the sacral vertebrae have each three ossific centres: one for the
central part, and one for the epiphyseal plates on its upper and under surface.
Occasionally the primary centres for the bodies of the first and second piece of the
sacrum are double.
65
The arch of each sacral vertebra is developed by two centres, one for each
lamina. These unite with each other behind, and subsequently join the body.
The lateral masses have six additional centres, two for each of the first three
vertebrae. These centres make their appearance above and to the outer side of
the anterior .sacral foramina (Fig. 33), and are developed into separate segments
(Fig. 34); they are subsequently blended with each other, and with the bodies
and transverse processes to form the lateral mass.
Lastly, each lateral surface of the sacrum is developed by two epiphyseal plates
(Fig. 35): one for the auricular surface, and one for the remaining part of the
thin lateral edge of the bone.
Additional centres
for the first three pieces.*
At birth.
Two epiphyseal laminx
for each lateral surface.®
At
25th year.
At 4k years.
FIG. 33. — Development of the sacrum.
FIG. 34.
FIG. 35.
Period of Development.— At about the eighth or ninth week of fetal life ossifi-
cation of the central part of the bodies of the first three vertebrae commences,
and at a somewhat later period that of the last two. Between the sixth and
eighth months ossification of the laminae takes place; and at about the same
period the centres for the lateral masses for the first three sacral vertebrae make
their appearance. The period at which the arch becomes completed by the junc-
tion of the laminae with the bodies in front and with each other behind varies in
different segments. The junction between the laminae and the bodies takes place
first in the lower vertebrae as early as the second year, but is not affected in the
uppermost until the fifth or sixth year. About the sixteenth year the epiphyses
for the upper and under surfaces of the bodies are formed, and between the eigh-
teenth and twentieth years those for each lateral surface of the sacrum make their
appearance. The bodies of the sacral vertebrae are, during early life, separated
from each other by intervertebral disks. But about the eighteenth year the two
lowest segments become joined together by ossification extending through the
disk. This process gradually extends upward until all the segments become
united, and the bone is completely formed from the twenty-fifth to the thirtieth
year of life.
Articulations. — With four bones': the last lumbar vertebra, coccyx, and the
two innominate bones.
Attachment of Muscles.— To eight pairs: in front, the Pyriformis and Coc-
cygeus, and a portion of the Iliacus to the base of the bone; behind, the Gluteus
maximus, Latissimus dorsi, Multifidus spinae, and Erector spinae, and sometimes
the Extensor coccygis.
Coccyx (os coccygis}. — The coccyx (xoxxoz, cuckoo], so called from having
been compared to a cuckoo's beak (Fig. 36), is usually formed of four small
segments of bone, the most rudimentary parts of the vertebral column (vertebrae
coccygeae or caudate vertebrae). In each of the first three segments may be traced
a rudimentary body, articular and transverse processes; the last piece (some-
5
66
THE SKELETON
times the third) is a mere nodule of bone, without distinct processes. All the
segments are destitute of pedicles, lamina?, and spinous processes, and, conse-
quently, of intervertebral foramina and spinal canal. The first segment is the
largest; it resembles the lowermost sacral vertebra, and often exists as a separate
Cornua.
Anterior surface.
Posterior surface.
FIG. 36. — Coccyx.
piece; the last three, diminishing in size from above downward, are usually
blended together so as to form a single bone. The gradual diminution in the size
of the pieces gives this bone a triangular form, the base of the triangle joining
the end of the sacrum. It presents for examination an anterior and posterior sur-
face, two borders, a base, and an apex.
Surfaces. Anterior Surface. — The anterior surface is slightly concave, and
marked with three transverse grooves, indicating the points of junction of the
different pieces. It has attached to it the anterior sacro-coccygeal ligament and
Levator ani muscle, and supports the lower end of the rectum.
Posterior Surface. — The posterior surface is convex, marked by transverse grooves
similar to those on the anterior surface; and presents on each side a lineal row
of tubercles, the rudimentary articular processes of the coccygeal vertebrae. Of
these, the superior pair are large, and are called the cornua of the coccyx (cornua
coccygea) ; they project upward, and articulate with the cornua of the sacrum, the
junction between these two bones completing the fifth posterior sacral foramen for
the transmission of the posterior division of the fifth sacral nerve.
Borders. — The lateral borders are thin, and present a series of small eminences,
which represent the transverse processes of the coccygeal vertebrae. Of these,
the first on each side is the largest, flattened from before backward, and often
ascends to join the lower part of the thin lateral edge of the sacrum, thus com-
pleting the fifth anterior sacral foramen for the transmission of the anterior
division of the fifth sacral nerve; the others diminish in size from above down-
ward, and are often wanting. The borders of the coccyx are narrow, and give
attachment on each side to the sacro-sciatic ligaments, to the Coccygeus muscles
in front of the ligaments, and to the Gluteus maximus behind them.
Base. — The base presents an oval surface for articulation with the sacrum.
This articulation is known as the sacro-coccygeal symphysis (symphysis sacro-
coccygea) .
Apex. — The apex is rounded, and has attached to it the tendon of the external
Sphincter muscle. It is occasionally bifid, and sometimes deflected to one or
other side.
Development. — The coccyx is developed by four centres, one for each piece.
Occasionally one of the first three pieces of this bone is developed by two centres,
placed side by side. The ossific nuclei make their appearance in the following
order: in the first segment, shortly after birth; in the second piece, at from five
THE VERTEBRAL COLUMN
67
to ten years; in the third, from ten to fifteen
years; in the fourth, from fifteen to twenty
years. As age advances these various seg-
ments become united with each other from
below upward, the union between the first
;in<l second segments being frequently delayed
until after the age of twenty-five or thirty.
At a late period of life, especially in females,
the coccyx often becomes joined to the end
of the sacrum.
Articulation. — With the sacrum.
Attachment of Muscles. — To four pairs
and one single muscle : on either side, the
Coccygeus ; behind, the Gluteus maximus
and Extensor coccygis, when present ; at the
apex, the Sphincter ani ; and in front, the
Levator ani.
1st cervical '
or Atlas.
2nd cervical '
or Axis.
6-
7-1
1st thoracic. -\
The Vertebral Column or Spine in General.
The spinal column (columna vertebralis) ,
formed by the junction of the vertebrae, is
situated in the median line, at the posterior
part of the trunk; its average length is about
two feet two or three inches, measuring along
the curved anterior surface of the column.
Of this length the cervical part measures
about five, the thoracic about eleven, the lum-
bar about seven inches, and the sacrum and
coccyx the remainder. The female spine is
about one inch less than that of the male.
Viewed in front, the ventral surface presents
two pyramids joined together at their bases,
the upper one being formed by all the verte-
brae from the second cervical to the last lum-
bar, the lower one by the sacrum and coccyx.
When examined more closely, the upper
pyramid is seen to be formed of three smaller
pyramids. The uppermost of these consists
of the six lower cervical vertebrae, its apex
being formed by the axis or second cervical,
its base by the first thoracic. The second
pyramid, which is inverted, is formed by the
four upper thoracic vertebrae, the base being
at the first thoracic, the smaller end at the
fourth. The third pyramid commences at the
fourth thoracic, and gradually increases in
size to the fifth lumbar.
Viewed laterally (Fig. 37), the spinal col-
umn presents several curves which correspond
to the different regions of the column, and are
called cervical, thoracic, lumbar, and pelvic.
The cervical curve commences at the apex of
the odontoid process, and terminates at the
1st lumbar.-
r,
Sacrum.
Coccyx.
FIG. 37. — Lateral view of the spine.
68 THE SKELETON
middle of the second thoracic vertebra; it is convex in front, and is the least
marked of all the curves. The thoracic curve, which is concave forward, com-
mences at the middle of the second, and terminates at the middle of the twelfth
thoracic vertebra. Its most prominent point behind corresponds to the spine
of the seventh thoracic vertebra. The lumbar curve commences at the middle
of the last thoracic vertebra, and terminates at the sacro-vertebral angle. It is
convex anteriorly; the convexity of the lower three vertebrae being much greater
than that of the upper two. The pelvic curve commences at the sacro-verte-
bral articulation and terminates at' the point of the coccyx. It is concave ante-
riorly. The thoracic and pelvic curves are the primary curves, and begin to be
formed at an early period of foetal life, and are due to the shape of the bodies
of the vertebrae. The cervical and lumbar curves are compensatory or secondary,
and are developed after birth in order to maintain the erect position. They are
due mainly to the shape of the intervertebral disks.
Some writers teach that the spine has a normal deviation to the right side.
Quain, Hyrtl, and others maintain this view. The curve is said to be in the
thoracic region. Bichat assigned muscular action as the chief cause of the curve.
Most persons use the right arm in preference to the left, especially in making
long-continued efforts, when the body is curved to the right side. In support
of this explanation is the observation made by Beclard that in some individuals
who were left-handed the lateral curvature was directed to the left side. Sappey
and others deny the existence of this curve.
The movable part of the spinal column presents for examination an anterior,
a posterior, and two lateral surfaces; a base, a summit, and the spinal canal.
Surfaces. Anterior Surface. — The anterior or ventral surface presents the bodies
of the vertebrae separated in the recent state by the intervertebral disks. The bodies
are broad in the cervical region, narrow in the upper part of the thoracic, and
broadest in the lumbar region. The whole of this surface is convex transversely,
concave from above downward in the thoracic region, and convex in the same
direction in the cervical and lumbar regions.
Posterior Surface. — The posterior or dorsal surface presents in the median line
the spinous processes. These are short, horizontal, with bifid extremities, in the
cervical region. In the thoracic region they are directed obliquely above, assume
almost a vertical direction in the middle, and are horizontal below, as are also
the spines of the lumbar vertebrae. They are separated by considerable intervals
in the loins, by narrower intervals in the neck, and are closely approximated in
the middle of the thoracic region. Occasionally one of these processes deviates a
little from the median line — a fact to be remembered in practice, as irregularities
of this sort are attendant also on fractures or displacements of the spine. On
either side of the spinous processes, extending the whole length of the column,
is the vertebral groove formed by the laminae in the cervical and lumbar regions,
where it is shallow, and by the laminae and transverse processes in the thoracic
region, where it is deep and broad. In the recent state these grooves lodge the
deep muscles of the back. External to each vertebral groove are the articular
processes, and still more externally is the transverse process. In the thoracic region
the latter processes stand backward, on a plane considerably posterior to that
of like processes in the cervical and lumbar regions. In the cervical region the
transverse processes are placed in front of the articular processes, and on the
outer side of the pedicles, between the intervertebral foramina. In the thoracic
region they are posterior to the pedicles, intervertebral foramina, and articular
processes. In the lumbar region they are placed also in front of the articular
processes, but behind the intervertebral foramina.
Lateral Surfaces. — The lateral surfaces are separated from the posterior surface
by the articular processes in the cervical and lumbar regions, and by the trans-
THE VERTEBRAL COLUMN 69
verse processes in the thoracic region. These surfaces present in front the sides of
the bodies of the vertebrae, marked in the thoracic region by the facets for articula-
tion with the heads of the ribs. More posteriorly are the intervertebral foramina,
formed by the juxtaposition of the intervertebral notches, oval in shape, smallest
in the cervical and upper part of the thoracic regions, and gradually increasing in
size to the last lumbar vertebra. They are situated between the transverse pro-
cesses in the neck, and in front of them in the back and loins, and transmit the
spinal nerves.
Base. — The base of that portion of the vertebral column formed by the twenty-
four movable vertebrte is formed by the under surface of the body of the fifth
lumbar vertebra; and the summit by the upper surface of the atlas.
Spinal Canal (canalis vertebralis). — The vertebral or spinal canal follows the
different curves of the spine; it is largest in those regions in which the spine
enjoys the greatest freedom of movement, as in the neck and loins, where it is
wide and triangular; and is narrow and rounded in the back, where motion is
more limited. The centre of gravity of the spine is in the upper lumbar region,
slightly to the right of the median plane (Struthers).
Surface Form. — The only parts of the vertebral column which lie closely under the skin, and
so directly influence surface form, are the apices of the spinous processes. These are always distin-
guishable at the bottom of a median furrow, which, more or less evident, runs down the mesial
line of the back from the external occipital protuberance above to the middle of the sacrum below.
In the cervical region the furrow is between the Trapezii muscles ; in the back and loins it is between
the Erector spinae muscles. In the neck the furrow is broad, and terminates in a conspicuous
projection, which is caused by the spinous process of the seventh cervical vertebra (vertebra
prominens). Above this the spinous process of the sixth cervical vertebra may sometimes be
seen to form a projection; the other cervical spines are sunken, and are not visible, though the
spine of the axis can be felt, and generally also the spines of the third, fourth, and fifth cervical
vertebrae. In the thoracic region the furrow is shallow, and during stooping disappears, and then
the spinous processes become more or less visible. The markings produced by these spines are
small and close together. In the lumbar region the furrow is deep, and the situation of the lumbar
spines is frequently indicated by little pits or depressions, especially if the muscles in the loins
are well developed and the spine incurved. They are much larger and farther apart than in the
thoracic region. In the sacral region the furrow is shallower, presenting a flattened area which
terminates below at the most prominent part of the posterior surface of the sacrum, formed by
the spinous process of the third sacral vertebra. At the bottom of the furrow may be felt the
irregular posterior surface of the bone. Below this, in the deep groove leading to the anus, the
coccyx may be felt. The only other portions of the vertebral column which can be felt from the
surface are the transverse processes of three of the cervical vertebrae — viz., the first, the sixth,
and the seventh. The transverse process of the atlas can be felt as a rounded nodule of bone
just below and in front of the apex of the mastoid process, along the anterior border of the sterno-
mastoid. The transverse process of the sixth cervical vertebra is of surgical importance. If
deep pressure be made in the neck in the course of the carotid artery, opposite the cricoid carti-
lage, the prominent anterior tubercle of the transverse process of the sixth cervical vertebra can
be felt. This has been named Chassaignac's tubercle, and against it the carotid artery may be
most conveniently compressed by the finger. The transverse process of the seventh cervical
vertebra can also often be felt. Occasionally the anterior root, or costal process, is large and
segmented off, forming a cervical rib.
Surgical Anatomy. — It is frequently necessary to locate certain vertebrae. Several of them
can be easily found and identified. The seventh cervical spine is conspicuously prominent, and
when the skin above it has been marked with a blue pencil the spine of the sixth cervical above
and of the first thoracic below may be located. The spine of the third thoracic vertebra is on a
level with the root of the spine of the scapula. The spine of the fourth lumbar vertebra is on a level
with the highest point of the iliac crest. When one or two vertebrae have been definitely recog-
nized the other ones can be found by counting the spines from a fixed point or from fixed points.
Over the fifth lumbar spine there is no prominence, but a depression. The third sacral spine
is on a level with the posterior superior spines of the ilium. The level at which the spinal cord
terminates should be known to the surgeon if he proposes to tap the spinal theca (lumbar punc-
ture), for diagnostic or therapeutic purposes or as a preliminary to the injection of cocaine or
eucaine (spinal anaesthesia). In an adult the cord terminates at the lower border of the first
lumbar vertebra, and the theca terminates opposite the body of the third sacral vertebra. In a
child the cord terminates opposite the body of the third lumbar vertebra, and the theca ends at
70 THE SKELETON
about the same level as in an adult. Hence, in either a child or an adult, a puncture below the
level of the fourth lumbar vertebra will inflict no injury upon the cord. In children the puncture
is made just beneath the vertebral spine, and in adults about one-half an inch to either side of
the vertebral spine, although, even in adults, the needle is made to enter the dura in the middle
line. In either case the needle is directed upward and forward. As previously pointed out, the
surgical anatomy of an infant's spine is not identical with the surgical anatomy of an adult's
spine. An infant's spine is larger comparatively than an adult's spine, because the lower limbs
are less developed in the former (A. H. Tubby). The umbilicus of an infant is opposite the body
of the fourth lumbar vertebra; in an adult it is opposite the spine of the third lumbar vertebra.
In an infant the base of the sternum is on a level with the top of the seventh cervical spine, and
in an adult of the second thoracic spine (A. H. Tubby).
Occasionally the coalescence of the laminae is not completed, and consequently a cleft is left
in the arches of the vertebrae and in the dura, through which a protrusion of the arachnoid
membrane and sometimes of the spinal cord itself takes place, constituting a malformation
known as spina bifida or hydrorrhachitis. This disease is most common in the lumbo-sacral
region; but it may occur in the thoracic or cervical region, or the arches throughout the whole
length of the canal may remain unapproximated. In some rare cases, in consequence of the
non-coalescence of the two primary centres from which the body is formed, a similar condition
may occur in front of the canal, the bodies of the vertebrae being found cleft and the tumor pro-
jecting into the thorax, abdomen . or pelvis, between the lateral halves of the bodies affected.
The construction of the spinal column of a number of pieces, securely connected together
and enjoying only a slight degree of movement between any two individual pieces, though per-
mitting of a very considerable range of movement as a whole, allows a sufficient degree of
mobility without any material diminution of strength. The main joints of which the spine is
composed, together with the very varied movements to which it is subjected, render it liable to
sprains, which may complicate other injuries or may exist alone; but so closely are the individual
vertebrae articulated that these sprains are seldom severe, and an amount of violence sufficiently
great to produce tearing of the ligaments would tend to cause a dislocation or fracture. The
further safety of the column and its less liability to injury is provided for by its disposition
in curves instead of in one straight line. For it is an elastic column, and must first bend before
it breaks : under these circumstances, being made up of three curves, it represents three columns,
and greater force is required to produce bending of a short column than of a longer one that is
equal to it in breadth and material. Again, the safety of the column is provided for by the inter-
position of the intervertebral disks between the bodies of the vertebrae, which act as admirable
buffers in counteracting the effects of violent jars or shocks. Fracture dislocation of the spine
may be caused by direct or indirect violence, or by a combination of the two, as when a person,
falling from a height, strikes against some prominence and is doubled over it. The fractures
from indirect violence are the more common, and here the bodies of the vertebrae are compressed,
whilst the arches are torn asunder; whilst in fractures from direct violence the arches are com-
pressed and the bodies of the vertebrae separated from each other. It will therefore be seen that
in both classes of injury the spinal marrow is the part least likely to be injured, and may escape
damage even where there has been considerable lesion of the bony framework. For, as Mr.
Jacobson states, "being lodged in the centre of the column, it occupies neutral ground in respect
to forces which might cause fracture. For it is a law in mechanics that when a beam, as of timber,
is exposed to breakage and the force does not exceed the limits of the strength of the material,
one division resists compression, another laceration of the particles, while the third, between
the two, is in a negative condition."1 Applying this principle to the spine it will be seen that,
whether the fracture dislocation be produced by direct violence or by indirect force, one segment,
either the anterior or posterior, will be exposed to compression, the other to laceration, and the
intermediate part, where the cord is situated, will be in a neutral state. When a fracture dis-
location is produced by indirect violence the displacement is almost always the same, the upper
segment being driven forward on the lower, so that the cord is compressed between the body of
the vertebra below and the arch of the vertebra above.
The parts of the spine most liable to be injured are (1) the dorso-lumbar region, for this part
is near the middle of the column, and there is therefore a greater amount of leverage, and more-
over the portion above is comparatively fixed, and the vertebrae which form it, though much
smaller, have nevertheless to bear almost as great a weight as those below; (2) the cervico-tho-
racic region, because here the flexible cervical portion of the spine joins the more fixed thoracic
region; and (3) the atlanto-axial region, because it enjoys an extensive range of movement, and,
being near the skull, is influenced by violence applied to the head. In fracture-dislocation spinous
processes and portions of the laminae may be removed (laminectomy} in order to free the cord
from pressure, and to permit the surgeon to explore, to arrest hemorrhage, to remove bone
fragments, or to apply sutures. Laminectomy is also resorted to in some cases of paraplegia due
to Pott's disease of the spine.
i Holmes's System of Surgery, 1883, vol. i. p. 529. — ED. of the 15th English Edition.
THE OCCIPITAL BONE
71
THE SKULL.
The skeleton of the head is called the skull. The cranium is the skull without
the mandible. The calvaria or cerebral cranium is the skull without the bones of
the face. The skull is supported on the summit of the vertebral column, and is
of an oval shape, wider behind than in front. It is composed of a series of flat-
tened or irregularly shaped bones which, with one exception (the lower jaw), are
immovably joined together. It is divided into two parts, the cerebral cranium or
calvaria and the visceral cranium or face, the former of which constitutes a case
for the accommodation and protection of the brain, while opening on the face
are the orifices of the nose and mouth; between the cerebral cranium above and
the face below the orbital cavities are situated. The cerebral cranium (xpdvos, a
helmet) is composed of eight bones — viz., the occipital, two parietal, frontal, two
temporal, sphenoid, and ethmoid. The face is composed of fourteen bones —
viz., the two nasal, two superior maxillary, two lachrymal, two malar, two palate,
two inferior turbinated, vomer, and inferior maxillary or mandible. The ossiculi
auditus, the teeth, and Wonnian bones are not included in this enumeration.
Cranium, 8 bones
Skull, 22 bones
Face, 14 bones
ital.
! Two" Parietal.
Frontal.
Two Temporal.
Sphenoid.
Ethmoid.
Two Nasal.
Two Superior Maxillary.
Two Lachrymal.
Two Malar.
Two Palate.
Two Inferior Turbinated.
Vomer.
Inferior Maxillary or Mandible.
The Hyoid Bone, situated at the root of the tongue and attached to the base
of the skull by ligaments, has also to be considered in this section.
THE CEREBRAL CRANIUM (CRANIUM CEREBRALE) (THE CALVARIA).
The Occipital Bone (Os Occipitale).
The occipital bone (ob, caput, against the head) is situated at the back part
and base of the cranium, is trapezoid in shape and is much curved on itself (Fig.
38). It presents at its front and lower part a large oval aperture, the foramen
magnum (foramen occipitale magnum) , by which the cranial cavity communicates
with the spinal canal. The portion of bone behind this opening is flat and
expanded and forms the tabula, tabular portion, or squamous part (squama
occipitalis) ; the portion in front is a thick, el ngated mass of bone, the basilar
process (pars basilaris) ; while on each side of the foramen is situated a lateral
or condylic portion (pars lateralis), bearing the condyle, by which the bone articu-
lates with the atlas. The bone presents for examination two surfaces, four borders,
and four angles.
Surfaces. External Surface.— The external surface is convex. Midway between
the summit of the bone and the posterior margin of the foramen magnum is a
prominent tubercle, the inion or external occipital- protuberance (protuberantia
72
THE SKELETON
occipitalis externa), and, descending from it as far as the foramen, a vertical
ridge, the external occipital crest (crista occipitalis externa). This protuberance
and crest give attachment to the ligamentum nuchte, and vary in prominence
in different skulls. Passing outward from the occipital protuberance is a semi-
circular ridge on each side, the superior curved or superior nuchal line (linea
nuchca superior). Above this line there is often a second less distinctly
marked ridge, called the highest curved line (linea nuchce suprema); to it the epi-
cranial aponeurosis is attached. The bone between these two lines is smoother
and denser than the rest of the surface. Running parallel with these from the
middle of the crest is another semicircular ridge on each side, the inferior curved
or inferior nuchal line (linea nuchae inferior}. The surface of the bone above the
linea suprema is rough and porous, and in the recent state is covered by the
Linea
suprema
SUPERIOR
CONSTRICTOR
of Pharynx.
FIG. 38.— Occipital bone. Outer surface.
Occipito-frontalis muscle. It is called the occipital portion or the planum
occipitale. The superior and inferior curved li-nes, together with the surfaces of
bone between and below them, serve for the attachment of several muscles.
The superior curved line gives attachment internally to the Trapezius, externally
to the muscular origin of the Occipito-frontalis, and to the Sterno-cleido-mastoid
to the extent shown in Fig. 38; the depressions between the curved lines to the
Cornplexus internally, the Splenius capitis and Obliquus capitis superior exter-
nally. The inferior curved line and the depressions below it afford insertion to
the Rectus capitis posticus, major and minor. The portion of the tabula below
the superior curved line is called the nuchal plane (planum nuchale), and it gives
attachment to certain of the neck muscles.
The foramen magnum (foramen occipitale magnum) is a large, oval aperture, its
long diameter extending from before backward. It transmits the lower portion
THE OCCIPITAL BONE 73
of the oblongata and its membranes, the accessory nerves, the vertebral
arteries, the anterior and posterior spinal arteries, and the occi pi to-axial
ligaments. Its back part is wide for the transmission of the oblongata, and the
corresponding margin rough for the attachment of the dura enclosing it; the
fore part is narrower, being encroached upon by the condyles; it has projecting
toward it, from below, the odontoid process, and its margins are smooth and
bevelled internally to support the oblongata. The middle of the anterior
wall of the foramen magnum is called by Broca the basion. The lateral or
condylic portions (partes laterales} are on either side of the foramen magnum
and bear the condyles for articulation with the atlas. Each condyle (condylus
occipitalis) is convex, oval, or reniform in shape, and directed downward and
outward. The condyles converge in front, and encroach slightly upon the anterior
segment of the foramen. On the inner border of each condyle is a rough tubercle
for the attachment of the ligaments (check) which connect this bone with the
odontoid process of the axis; while external to them is a rough tubercular promi-
nence, the transverse or jugular process (processus jugularis), channelled in front
by a deep notch (incisura jugularis), which forms part of the jugular foramen
or foramen lacerum posterius. The under surface of this process presents an
eminence (processus intrajugularis) which represents the paramastoid process of
some mammals. The eminence is occasionally large, and extends as low as the
transverse process of the atlas. This surface affords attachment to the Rectus
capitis lateralis muscle and to the lateral occipito-atlantal ligament; its upper or
cerebral surface presents a deep groove which lodges part of the lateral sinus,
while its external surface is marked by a quadrilateral rough facet, covered with
cartilage in the fresh state, and articulating with a similar surface on the petrous
portion of the temporal bone. On the outer side of each condyle, near its fore
part, is a foramen, the anterior condyloid foramen (canalis hypoglossi or the hypo-
glossal canal) ; it is directed downward, outward, and forward, and transmits the
hypoglossal nerve, and occasionally a meningeal branch of the ascending pharyn-
geal artery. This foramen is sometimes double. Behind each condyle is a
fossa1 (fossa condyloideus), sometimes perforated at the bottom by a foramen,
the posterior condyloid foramen (canalis condyloideus), for the transmission of a
vein to the lateral sinus. The basilar process (pars basilaris) is a strong quadri-
lateral plate of bone, which is wider behind than in front, and is situated in front
of the foramen magnum. Its under surface, which is rough, presents in the
median line a tubercular ridge, the pharyngeal spine or tubercle (tuberculum
pharyngeum), for the attachment of the tendinous raphe* and Superior con-
strictor of the pharynx; and on each side of it rough depressions for the attach-
ment of the Rectus capitis anticus, major and minor.
Internal Surface. — The internal or cerebral surface (Fig. 39) is deeply concave.
The posterior or tabular part is divided by a crucial ridge into four fossae. The
two superior fossae receive the occipital lobes of the cerebrum, and present slight
eminences and depressions corresponding to their convolutions. The two inferior,
which receive the hemispheres of the cerebellum, are larger than the former, and
comparatively smooth; both are marked by slight grooves for the lodgement of
arteries. At the point of meeting of the four divisions of the crucial ridge is an
eminence, the internal occipital protuberance (protuberantia occipitalis interna). It
nearly corresponds to that on the outer surface, though it is often on a slightly
higher level, and is perforated by one or more large vascular foramina. From
this eminence the superior division of the crucial ridge runs upward to the supe-
rior angle of the bone; it presents a deep groove, the sagittal sulcus (sulcus sagit-
1 This fossa presents many variations in size. It is usually shallow, and the foramen small: occasionally
wanting on one or both sides. Sometimes both fossa and foramen are large, but confined to one side only; more
rarely, the fossa and foramen are very large on both sides. — ED. of 15th English Edition.
74
THE SKELETON
talis) , for the superior longitudinal sinus. The margins of the groove give attach-
ment to the falx cerebri. The inferior division, the internal occipital crest (crista
occipitalis internet) , runs to the posterior margin of the foramen magnum, on the
edge of which it becomes gradually lost; this ridge, which is bifurcated below, serves
Superior angle.
Lateral
Angle.
Inferior angle.
FIG. 39. — Occipital bone. Inner surface.
for the attachment of the falcula. It is usually marked by a single groove, which
commences at the back part of the foramen magnum and lodges the occipital
sinus. Occasionally the groove is double where two sinuses exist. A transverse
groove (sulcus transversus) passes outward on each side to the lateral angle.
The grooves are deep channels for the lodgement of the lateral sinuses, their
prominent margins affording attachment to the tentorium.1 At the point of
meeting of these grooves is a depression, the torcular,2 placed a little to one or
the other side of the internal occipital protuberance. More anteriorly is the fora-
men magnum, and on each side of it, but nearer its anterior than its posterior
part, the internal openings of the anterior condyloid foramen. On the supe-
rior aspect of the lateral portion of the bone the jugular tubercle (tuberculum
jugulare) is seen. This corresponds to the portion of bone which roofs in the
anterior condyloid foramen. The internal openings of the posterior condyloid
1 Usually one of the transverse grooves is deeper and broader than the other; occasionally, both grooves are
of equal depth and breadth, or both equally indistinct. The broader of the two transverse grooves is nearly
always continuous with the vertical groove for the superior longitudinal sinus. — ED. of 15th Knglish Edition.
2 The columns of blood coming in different directions were supposed to be pressed together at this point
(torcular, a wine-press). — ED. of 15th English Edition.
THE OCCIPITAL BONE 75
foramina are a little external and posterior to the openings of the anterior con-
dyloid foramina, protected by a small arch of bone. At this part of the internal
surface there is a very deep groove in which the posterior condyloid foramen,
when it exists, has its termination. This groove is continuous, in the complete
skull, with the transverse groove on the posterior part of the bone, and lodges
the end of the same sinus, the lateral. In front of the foramen magnum is the
basilar process, presenting a shallow depression, the basilar groove (clivus), which
slopes from behind, upward and forward, and supports the oblongata and part
of the pons Varolii, and on each side of the basilar process is a narrow channel,
which, when united with a similar channel on the petrous portion of the temporal
bone, forms a groove (sulcus petrosus inferior) which lodges the inferior petrosal
sinus.
Borders. Superior Border. — The superior border, lambdoidal margin (margo
lambda ideus) , extends on each side from the superior to the lateral angle, is
deeply serrated for articulation with the parietal bone, and forms, by this union,
the lambdoid suture.
Inferior Border. — The inferior border extends from the lateral to the inferior
angle; its upper half, mastoid margin (margo mastoideus}, is rough, and articu-
lates with the mastoid portion of the temporal, forming the masto-occipital suture ;
the inferior half articulates with the petrous portion of the temporal, forming
the petro-occipital suture; these two portions are separated from one another by
the jugular process. In front of this process is a deep notch, which, with a
similar one on the petrous portion of the temporal, forms the jugular foramen
(foramen lacerum posterius). This notch is occasionally subdivided into two
parts by a small process of bone (processus intraj ugularis) , and it generally
presents an aperture at its upper part, the internal opening of the posterior
condyloid foramen.
Angles. Superior Angle. — The superior angle is received into the interval
between the posterior superior angles of the two parietal bones; it corresponds
with that part of the skull in the foetus which is called the posterior fontanelle
(lambda).
Inferior Angle. — The inferior angle is represented by the square-shaped surface
of the basilar process. At an early period of life a layer of cartilage separates this
part of the bone from the sphenoid,
but in the adult the union between
them is osseous.
Lateral Angles. — The lateral an- ___
gles correspond to the outer ends of 1^4 for occipital
the transverse grooves, and are re- ^ "^HlF P°rtion-
ceived into the interval between the
posterior inferior angles of the pari-
etal and the mastoid portion of the the* pieces j^ffi ^%\~~1 f°r each condyloid •)
temporal. The junction of the oc- separate. ufr\ )l]u portion.
cipital, parietal, and temporal bones ^^^d&^&^ \ &
was named the asterion by Broca. \^jj — i for basilar portion, j "?
Structure. The Occipital bone FIG. 40. — Development of occipital bone. By seven centres.
consists of two compact lamina?,
called the outer and inner tables, having between them the diploic tissue; this bone
is especially thick at the ridges, protuberances, condyles, and anterior part of the
basilar process; while at the bottom of the fossa?, especially the inferior, it is thin,
semitransparent, and destitute of diploe.
Development (Fig. 40). — At birth the bone consists of four distinct parts: a
tabular squamous or expanded portion, which lies behind the foramen magnum ; two
condylic parts, which form the sides of the foramen; and a basilar part, which lies
76 THE SKELETON
in front of the foramen. The number of nuclei for the tabular part vary. As
a rule, there are four, but there may be only one (Blandin) or as many as eight
(Meckel). They appear about the eighth week of foetal life, and soon unite to
form a single piece, which is, however, fissured in the direction indicated in
Fig. 40. The basilar and two condyloid portions are each developed from a single
nucleus, which appears a little later. The upper portion of the tabular surface
— that is to say, the portion above the transverse fissure— is developed from mem-
brane, and may remain separated from the rest of the bone throughout life, when
it constitutes the interparietal bone, which is called the os incae, because of its fre-
quent occurrence in Peruvian skulls. The rest of the bone is developed from
cartilage. At about the fourth year the tabular and the two condyloid pieces
join, and about the sixth year the bone consists of a single piece. At a later period,
between the eighteenth and twenty-fifth years, the occipital and sphenoid become
united, forming a single bone.
Articulations. — With six bones: two parietal, two temporal, sphenoid, and atlas.
Attachment of Muscles. — To twelve pairs: to the superior curved line are
attached the Occipito-frontalis, Trapezius, and Sterno-cleido-mastoid. To the
space between the curved lines, the Complexus,1 Splenius capitis, and Obliquus
capitis superior; to the inferior curved line, and the space between it and the
foramen magnum, the Rectus capitis posticus, major and minor; to the transverse
process, the Rectus capitis lateralis; and to the basilar process, the Rectus capitis
anticus, major and minor, and Superior constrictor of the pharynx.
The Parietal Bone (Os Parietale).
The parietal bones (paries, a wall) are paired bones and form, by their union, the
sides and roof of the cerebral cranium. Each bone is of an irregular quadrilateral
form, and presents for examination two surfaces, four borders, and four angles.
Surfaces. External Surface (fades parietalis). — The external surface (Fig. 41)
is convex, smooth, and marked about its centre by an eminence called the
parietal eminence (tuber parietale), which indicates the point where ossification
commenced. Crossing the middle of the bone in an arched direction are two
well-marked curved lines or ridges, the upper and lower temporal lines or ridges
(linea temporalis superior et inferior); the former gives attachment to the tem-
poral fascia, while the latter indicates the upper limit of the origin of the
Temporal muscle. These lines form the temporal crest. Above these ridges
the surface of the bone is rough and porous, and covered by the aponeurosis
of the Occipito-frontalis ; between them the bone is smoother and more polished
than the rest; below them the bone forms part of the temporal fossa. This
portion of bone is called the planum temporale, and affords attachment to the
Temporal muscle. The superior stephanion is the intersection of the upper
temporal ridge with the coronal suture. The inferior stephanion is the intersec-
tion of the lower temporal ridge with the coronal suture. At the back part of
the superior border, close to the sagittal suture, is a small foramen, the parietal
foramen (foramen parietale), which transmits the emissary vein of Santorini from
the scalp to the superior longitudinal sinus. It sometimes also transmits a
small branch of the occipital artery. Its existence is not constant, and its
size varies considerably. The point on the sagittal suture, between the parietal
foramina, is the obelion.
Internal or Cerebral Surface (fades cerebralis) . — The internal surface (Fig. 42) is
concave, presents depressions for lodging the convolutions of the cerebrum and
numerous furrows, for the ramifications of the middle meningeal artery; the
1 To these the Biventer cervicis should be added, if it is regarded as a separate muscle. — ED. of 15th English
Edition.
THE PARIETAL BONE
with opposite pariet
77
Squamous portion of
temporal bone.
FIG. 41. — Left parietal bone. External surface.
Posterior
superior
angle.
^Anterior
superior
angle.
Posterior
inferior
angle.
FIG. 42. — Left parietal bone. Internal surface.
Anterior
inferior
angle.
78 THE SKELETON
latter runs upward and backward from the anterior inferior angle and from the
central and posterior part of the lower border of the bone. The depression for
the middle meningeal artery at the anterior and inferior portions of the cerebral
surface of the bone is called the sulcus arteriosus. Sometimes a distinct canal
exists for the artery, but it never remains a canal for a long distance. Along
the upper margin of the bone is part of a shallow groove, which, when joined
to the opposite parietal, forms a channel for the superior longitudinal sinus (the
sulcus sagittalis). The elevated edges of the groove afford attachment to the
falx. Near the groove are seen several depressions, Pacchionian depressions (foveolae
granulares [Pacchioni]}. They are most frequently found in the skulls of old per-
sons, and lodge the arachnoid villi (Pacchionian bodies}. The internal opening of
the parietal foramen is also seen when that aperture exists. On the inner surface
of the posterior inferior portion of the bone is a portion of the groove for the lodge-
ment of the lateral sinus.
Borders. Superior Border. — The superior border, sagittal margin (margo sagit-
talis), the longest and thickest, is dentated to articulate with its fellow of the
opposite side, forming the sagittal suture.
Inferior Border. — The inferior border, squamous margin (margo squamosus), is
divided into three parts: of these, the anterior is thin and pointed, bevelled at
the expense of the outer surface, and overlapped by the tip of the great wing
of the sphenoid; the middle portion is arched, bevelled at the expense of the
outer surface, and overlapped by the squainous portion of the temporal; the
posterior portion is thick and serrated for articulation with the mastoid portion
of the temporal.
Anterior Border. — The anterior border, frontal margin (margo frontalis), deeply
serrated, is bevelled at the expense of the outer surface above and of the inner
below; it articulates with the frontal bone, forming the coronal suture.
Posterior Border. — The posterior border, occipital margin (margo occipitalis),
deeply denticulated, articulates with the occipital, forming the lambdoid suture.
Angles. Anterior Superior Angle (angulus frontalis). — The anterior superior
or frontal angle, thin and pointed, corresponds with that portion of the skull
which in the foetus is membranous, and is called the anterior fontanelle (bregma).
Anterior Inferior Angle (angulus sphenoidalis) . — The anterior inferior or
sphenoidal angle is thin and lengthened, being received in the interval between
the great wing of the sphenoid and the frontal. Its inner surface is marked by a
deep groove, sometimes a canal, for the anterior branch of the middle meningeal
artery. At the anterior inferior angle the parietal, temporal, and frontal bones
and the greater wing of the sphenoid bone meet. This spot is called the
pterion.
Posterior Superior Angle (angulus occipitalis) . — The posterior superior or occip-
ital angle corresponds with the junction of the sagittal and lambdoid sutures. In
the foetus this part of the skull is membranous, and is called the posterior fonta-
nelle (lambda).
Posterior Inferior Angle (angulus mastoideus. — The posterior inferior or mas-
toid angle articulates with the mastoid portion of the temporal bone, and
generally presents on its inner surface a broad, shallow groove for lodging part
of the lateral sinus.
Development. — The parietal bone is formed in membrane, being developed
by one centre, which corresponds with the parietal eminence, and makes its first
appearance about the seventh or eighth week of foetal life. Ossification gradually
extends from the centre to the circumference of the bone: the angles are conse-
quently the parts last formed, and it is in their situation that the fontanelles exist
previous to the completion of the growth of the bone. Occasionally the parietal
bone is divided into two parts, upper and lower, by an antero-posterior suture.
THE FRONTAL BONE
79
Articulations. — With five bones: the opposite parietal, the occipital, frontal,
temporal, and sphenoid.
Attachment of Muscles. — One only, the Temporal.
The Frontal Bone (Os Frontale).
The frontal bone (frons, the forehead) resembles a cockle-shell in form, and
consists of two portions — a vertical or frontal portion, situated at the anterior
part of the cranium, forming the forehead; and a horizontal or orbital portion,
which enters into the formation of the roof of the orbits and nasal fossae.
Vertical Portion of the Frontal Bone (Pars Frontalis).
Surfaces. External Surface (fades Jrontalis] (Fig. 43). — In the median line,
traversing the bone from the upper to the lower part, is occasionally seen a
slightly elevated ridge, and in young subjects a suture, the frontal (metopic)
suture, which represents the line of union of the two lateral halves of which the
- , External
angular process. angvlar proceS8.
Nasal I spine.
FIG. 43. — Frontal bone. Outer surface.
bone consists at an early period of life; in the adult this suture is usually oblit-
erated and the bone forms one piece; traces of the obliterated suture are, how-
ever, generally perceptible at the lower part. On either side of this ridge, a little
below the centre of the bone, is a rounded eminence, the frontal eminence (tuber
frontale). These eminences vary in size in different individuals, and are occa-
sionally unsymmetrical in the same subject. They are especially prominent in
cases of well-marked cerebral development. The whole surface of the bone
above this part is smooth, and covered by the aponeurosis of the Occipito-
frontalis muscle. Below the frontal eminence and separated from it by a slight
80 THE SKELETON
groove is the superciliary ridge (arcus superciliaris} , broad internally, where it
is continuous with the nasal eminence, but less distinct as it arches outward.
These ridges are caused by the projection outward of the frontal air sinuses,1
and give attachment to the Orbicularis palpebrarum and Corrugator supercilii.
Between the two superciliary ridges is a smooth, flat surface, the glabella.
Nearly corresponding with the glabella is the ophryon, a point in the mid-line
on a level with the upper border of the eyebrows, which is the centre of the
narrowest transverse diameter of the forehead. Beneath the superciliary ridge
is the orbital margin or supraorbital arch (mar go supraorbitalis), a curved and
prominent margin, which forms the upper boundary of the orbit and separates
the vertical from the horizontal portion of the bone. The outer part of the
arch is sharp and prominent, affording to the eye, in that situation, considerable
protection from injury; the inner part is less prominent. At the junction of the
internal and middle third of this arch is a notch, sometimes converted into a
foramen, and called the supraorbital notch or foramen (incisura supraorbitalis or
foramen supraorbitale) . It transmits the supraorbital artery, vein, and nerve. A
small aperture is seen in the upper part of the notch, which transmits a vein
from the diploe to join the supraorbital vein. To the median side of the
supraorbital notch there is often a notch (incisura frontalis) for the passage
of the frontal artery and frontal nerve. The supraorbital arch terminates
externally in the external angular process (processus zygomaticus) and internally
in the internal angular process. The external angular process is strong, prominent,
and articulates with the malar bone; running upward and backward from it are
two well-marked lines, which, commencing together from the external angular
process as the temporal ridge, crest or line (linea temporalis), soon diverge from
each other and run in a curved direction across the bone. These are the
upper and lower temporal ridges; the upper gives attachment to the temporal
fascia, the lower to the Temporal muscle. Beneath them is a slight concavity
that forms the anterior part of the temporal fossa and gives origin to the
Temporal muscle. The internal angular processes are less marked than the
external, and articulate with the lachrymal bones. Between the internal angular
processes is a rough, uneven interval, the nasal notch, which articulates in the
middle line with the nasal bone, and on either side with the nasal process of the
superior maxillary bone. From the concavity of this notch projects a process,
the nasal process, which extends beneath the nasal bones and nasal processes of
the superior maxillary bones and supports the bridge of the nose. On the under
surface of this is a long, pointed process, the nasal or frontal spine (spina nasalis
or frontalis), and on either side a small grooved surface enters into the formation
of the roof of the nasal fossa. The nasal spine forms part of the septum of the
nose, articulating in front with the nasal bones and behind with the perpen-
dicular plate of the ethmoid. The junction of the nasal and frontal bones is
called the nasion.
Internal Surface (cerebral surface, fades cerebralis) (Fig. 44). — Along the middle
line is a vertical groove, the sulcus sagittalis, the edges of which unite below to
form a ridge, the frontal crest (crista frontalis) ; the groove lodges the superior
longitudinal sinus, whilst its margins afford attachment to the falx. The crest
terminates below at a small notch which is converted into a foramen by artic-
ulation with the ethmoid. It is called the foramen caecum, and varies in size in
different subjects: it is sometimes partially or completely impervious, lodges a
1 Some confusion is occasioned to students commencing the study of anatomy by the name "sinuses" having
been given to two perfectly different kinds of spaces connected with the skull. It may be as well, therefore, to
state here at the outset, that the "sinuses" in the interior of the cranium which produce the grooves on the
inner surface of the bones are venous channels along which the blood runs in its passage back from the brain,
while the "sinuses" external to the cranial cavity (the frontal sphenoidal, ethmoidal, and maxillary) are hollow
spaces in the bones themselves which communicate with the nostrils, and contain air. — ED. of 15th English
Edition.
THE FRONTAL BONE
81
process of the falx, and when open transmits a vein from the lining membrane of
the nose to the superior longitudinal sinus. On either side of the groove the bone
is deeply concave, presenting depressions for the convolutions of the brain, and
numerous small furrows for lodging the ramifications of the anterior branches
of the middle meningeal arteries. Several small irregular fossae are seen also on
either side of the groove, for the reception of the arachnoid villi.
With superior maxillary.
With nasal'.
Frontal sinus.
\Under surface of nasal process,
With perpendicular plate of ethmoid. ' forming part of roof of nose.
Fio. 44. — Frontal bone. Inner surface.
Border. — The border of the vertical portion is thick, strongly serrated, bevelled
at the expense of the internal table above, where it rests upon the parietal bones,
and at the expense of the external table at each side, where it receives the lateral
pressure of those bones; this border is continued below into a triangular rough
surface which articulates with the great wing of the sphenoid.
Structure. — The vertical portion and external angular processes are very thick,
consisting of diploic tissue contained between two compact laminae.
Horizontal or Orbital Portion of the Frontal Bone (Pars Orbitalis).
This portion of the bone consists of two thin plates, the orbital plates, which
form the vault of the orbit, separated from one another by a median gap, the
ethmoidal notch.
Surfaces. External Surface. — The inferior or external surface of each orbital
plate (fades orbitalis) consists of a smooth, concave, triangular lamina of bone,
marked at its anterior and external part (immediately beneath the external
angular process) by a shallow depression, the lachrymal fossa (fossa glandidae
lacrimalis) for lodging the lachrymal gland; and at its anterior and internal part
6
82
THE SKELETON
by a depression (sometimes a small tubercle), the trochlear fossa (fovea trochlearis),
for the attachment of the cartilaginous pulley of the Superior oblique muscle of
the eye. The ethmoidal notch (incisura ethmoidalis) separates the two orbital
plates; it is quadrilateral, and filled up, when the bones are united, by the cribri-
form plate of the ethmoid. The margins of this notch present several half-cells,
which, when united with corresponding half-cells on the upper surface of the eth-
moid, complete the ethmoidal cells; two grooves are also seen crossing these edges
transversely; they are converted into canals by articulation with the ethmoid, and
are called the anterior and posterior ethmoidal foramina or canals (foramen ethmoi-
dale anterius and foramen ethmoidale postering) : they open on the inner wall of the
orbit. The anterior one transmits the nasal nerve and anterior ethmoidal vessels,
the posterior one the posterior ethmoidal vessels. In front of the ethmoidal
notch, on each side of the nasal spine, is the opening of the frontal air sinus (sinus
frontalis). These are two irregular cavities, which extend upward and outward, a
variable distance, between the two tables of the skull, and are separated from one
another by a thin, bony septum (septum sinuum frontalium), which is often dis-
placed to one side. Within the sinuses imperfect trabeculae of bone often exist. The
sinuses are beneath and give rise to the prominences above the supraorbital arches
called the superciliary ridges (arcus superciliares) . The frontal air sinuses are absent
at birth, become apparent about the seventh year of life, and from this period until
the age of twenty increase gradually in size. Sometimes, however, the sinuses
remain very small or never develop at all — or one side may be large and the other
small — or one may exist on one side and be absent on the other.1 The right sinus
is usually the larger. These cavities are larger in men than in women. The floor
of each sinus is very thin and is over the orbit and the upper border of the lateral
mass of the ethmoid. The thinnest portion of the floor is at the upper and
inner angle of the orbit, and at this point pus is apt to point in cases of
empyema of the sinus. The frontal sinuses are lined by mucous membrane
and each sinus communicates with the middle meatus of the nose by the infun-
dibulum and part of the semilunar hiatus. In some cases the sinuses commu-
nicate with each other by means of an aperture in the septum and occasionally
join the sinus in the crista galli of the ethmoid.2
Internal Surface (cerebral surface, fades cerebralis). — The internal surface of
the horizontal portion presents the convex upper surfaces of the orbital plates,
separated from each other in the mid-
dle line by the ethmoidal notch, and
marked by eminences and depressions for
the convolutions of the frontal lobes of
the brain.
Border. — The border of the horizontal
portion is thin, serrated, and articulates
with the lesser wing of the sphenoid.
Structure. — The horizontal portion is
thin, translucent, and composed entirely
of compact tissue; hence the facility with
which instruments can penetrate the
cranium through this part of the orbit.
Development (Fig. 45). — The frontal
bone is formed in membrane, being
developed by two centres, one for each lateral half, which make their appearance
about the seventh or eighth week, above the orbital arches. From this point
ossification extends, in a radiating manner, upward into the forehead and back-
FIG. 45. — Frontal bone at birth,
two lateral halves.
Developed by
1 Dr. D. Kerfoot Shute. Article on the Skull, in Reference Handbook of the Medical Sciences.
2 Ibid.
THE TEMPORAL BONE
83
ward over the orbit. At birth the bone consists of two pieces, which afterward
become united, along the middle line, by a suture which runs from the vertex
to the root of the nose. This suture usually becomes obliterated within a few
years after birth; but it occasionally remains throughout life, constituting the
metopic suture. Secondary centres of ossification appear for the nasal spine —
one on either side of the internal angular process where it articulates with the
lachrymal bone; and sometimes there is one on either side at the lower end of
the coronal suture. This latter centre sometimes remains ununited, and is
known as the pterion ossicle, or it may join with the parietal, sphenoid, or tem-
poral bone.
Articulations. — With twelve bones: two parietal, the sphenoid, the ethmoid,
two nasal, two superior maxillary, two lachrymal, and two malar.
Attachment of Muscles. — To three pairs: the Corrugator supercilii, Orbicu-
laris palpebrarum, and Temporal, on each side.
The Temporal Bone (Os Temporale).
The temporal bones (tempus, time) are paired bones, situated at the sides and
base of the skull. Each presents for examination a squamous, mastoid, and petrous
portion.
Squamous Portion of the Temporal Bone (Squama Temporalis) .
The squamous portion (squama, a scale), the anterior and upper part of the
' bone, is scale-like in form, and thin and translucent in texture (Fig. 46).
MOUS
If TE
SQUAMOUS SUTURE
TEMPORAL FASCIA
SULCUS FOR MIDDLE
TEMPORAL ARTERY
REMAINS OF
SQUAMOSO-
MASTOID
SUTURE
MASTOID
FOSSA
SUPRA-
MEATAL
SPINE
APEX OF PETROUS
PORTION
MASTOID
FORAMEN f
MASTOID
PORTION
PETROTYMPANIC OH
GLASERIAN FISSURE
VAGINAL PORTION
OF STYLOID
EXTERNAL AUDITORY MEATUS TYMPANIC PORTION
FIG. 46. — Right temporal bone, from without. (Spaltekolz.)
Surfaces. Outer Surface (fades temporalis) . — Its outer surface is smooth, convex,
and grooved at its back part for the middle or deep temporal artery (sulcus a.
temporalis mediae); it affords attachment to a portion of the Temporal muscle and
forms part of the temporal fossa. At its back part may be seen a curved ridge —
part of the temporal ridge or line; it serves for the attachment of the temporal
84 THE SKELETON
fascia and limits the origin of the Temporal muscle. The boundary between the
squamous and mastoid portions of the bone, as indicated by traces of the original
suture, lies fully half an inch below this ridge. Projecting from the lower part of
the squamous portion is a long, arched process of bone, the zygoma or zygomatic
process (processus zygomaticus) . This process is at first directed outward, its
two surfaces looking upward and downward; it then appears as if twisted
upon itself, and runs forward, its surfaces now looking inward and outward.
The superior border of the process is long, thin, and sharp, and serves for the
attachment of the temporal fascia. The inferior, short, thick, and arched, has
attached to it some fibres of the Masseter muscle. Its outer surface is convex
and subcutaneous; its inner is concave, and also affords attachment to the
Masseter. The extremity, broad and deeply serrated, articulates with the malar
bone. The zygomatic process is connected to the temporal bone by three divi-
sions, called its roots — an anterior, middle, and posterior. The anterior, wrhich
is short, but broad and strong, is directed inward, to terminate in a rounded
eminence, the eminentia articularis or articular eminence (tuberculum articulare)
(Fig. 46). This eminence forms the front boundary of the glenoid or mandibular
fossa (fossa mandibular is), and in the recent state is covered with cartilage.
The middle root is known as the post-glenoid process or tubercle, and is very
prominent in young bones. It separates the mandibular portion of the glenoid
fossa from the external auditory meatus, and terminates at the commencement
of a well-marked fissure, the Glaserian (petro-tympanic) fissure (fissura petro-
tympanica [Glaseri]). The posterior root, which is strongly marked, runs from
the upper border of the zygoma backward over the external auditory meatus.
It is termed the supramastoid or temporal crest, and forms part of the lower
temporal ridge. At the junction of the anterior root with the zygoma is a
projection, called the tubercle, for the attachment of the external lateral liga-
ment of the lower jaw; and between the anterior and middle roots is an oval
depression, forming part of the glenoid (mandibular) fossa (fAyvy, a socket), for
the reception of the condyle of the lower jaw. This fossa is bounded, in front,
by the eminentia articularis; behind, by the tympanic plate, which separates it
from the external auditory meatus; it is divided into two parts by a narrow slit,
the Glaserian or petro-tympanic fissure. The anterior or mandibular part, formed
by the squamous portion of the bone, is smooth, covered in the recent state with
cartilage, and articulates with the condyle of the lower jaw. This part of the
glenoid fossa presents posteriorly a small conical eminence, the post-glenoid
process, already referred to. This process is the representative of a prominent
tubercle which, in some of the mammalia, descends behind the condyle of the
jaw, and prevents it being displaced backward during mastication (Humphry).
The posterior part of the glenoid fossa, which lodges a portion of the parotid
gland, is formed chiefly by the tympanic plate, which constitutes the anterior
wall of the tympanum and external auditory meatus. The plate of bone termi-
nates above in the Glaserian fissure, and below forms a sharp edge, the vaginal
process of the styloid (vagina processus styloidei), which gives origin to some of
the fibres of the Tensor palati muscle. The Glaserian fissure, which leads into
the tympanum, lodges the processus gracilis of the malleus, and transmits the
tympanic branch of the internal maxillary artery. The chorda tympani nerve
passes through a separate canal, parallel to the Glaserian fissure, the canal of
Huguier (canaliculus chordcp tympani), on the outer side of the Eustachian
tube, in the retiring angle between the squamous and petrous portions of the
temporal bone.1 Between the posterior bony wall of the external auditory meatus
1 This small fissure must not be confounded with the large canal which lies above the Eustachian tube and
transmits the Tensor tympani muscle.
THE TEMPORAL BONE
85
and the posterior root of the zygoma is the area called the suprameatal triangle of
Prof. Macewen. Through this space the surgeon pushes the gouge in order to
carry it into the antrum of the mastoid process.
Internal Surface (cerebral surface, fades cerebralis}. — The internal surface of
the squamous portion (Fig. 47) is concave, presents numerous eminences and
depressions for the convolutions of the cerebrum, and two well-marked grooves
for the branches of the middle meningeal artery.
parietal
Aquseductus vestibuli.
Depression for dura.
Meatus auditorius internus.
Eminence for superior semicircular canal.
Hiatus Fallopii.
Opening for. smaller petrosal nerve.
Depression for Gasserian Ganglion.
— Bristle passed through carotid canal.
FIG. 47. — Left temporal bone. Inner surface.
Borders. Superior Border. — The superior border, parietal margin (margo
parietalis), is thin, bevelled at the expense of the internal surface, so as to
overlap the lower border of the parietal bone, forming the squamous suture.
Anterior Inferior Border. — The anterior inferior border, sphenoidal margin (margo
sphenoidalis), is thick, serrated, and bevelled, alternately at the expense of the
inner and outer surfaces, for articulation with the great wing of the sphenoid.
Posterior Inferior Border. — The posterior inferior border, occipital margin
(margo occipitalis), is serrated and articulates with the occipital bone.
The Mastoid Portion of the Temporal Bone (Pars Mastoidea).
The mastoid portion (/jtaaroz, a nipple or teat) is situated at the posterior part
of the bone (Figs. 46, 48, and 49).
Surfaces. Outer Surface. — The outer surface of the mastoid is rough, and
gives attachment to the Occipito-frontalis and Retrahens aurem muscles. It
is perforated by numerous foramina; one of these, of large size, situated at the
posterior border of the bone, is termed the mastoid foramen (foramen mastoideum} ;
it transmits a vein to the lateral sinus and a small artery from the occipital to
supply the dura. The position and size of this foramen are very variable. It
is not always present; sometimes it is situated in the occipital bone or in the
suture between the temporal and the occipital. The mastoid portion is con-
86
THE SKELETON
tinned below into a conical projection, the mastoid process (processus mastoideus) ,
the size and form of which vary somewhat. The mastoid process begins to
develop during the second year and does not attain full size until after puberty.
This process serves for the attachment of the Sterno-mastoid, Splenius capitis,
and Trachelo-mastoid muscles. On the inner side of the mastoid process is a
deep groove, the digastric fossa (incisura mastoidea), for the attachment of the
Digastric muscle; and, running parallel with it, but more internal, the occipital
groove (sulcus a. occipitalis) , which lodges the occipital artery. The suprameatai
triangle of Prof. Macewen is bounded by the posterior root of the zygoma, the
posterior bony wall of the external auditory meatus, and an imaginary line join-
ing these two. Through this triangle the surgeon enters his instrument in order
to reach the mastoid antrum. Behind the suprameatai spine is a depression
known as the mastoid fossa (fossa mastoidea), which contains numerous small
openings for bloodvessels.
Tensor tympani.
•Proc. cochleariformis.
'Eustachian tube.
'Carotid canal.
Carotid cana
Fenestra rotunda.
Pyramid.
FIG. 48. ^-Section through the
•Styloid process.
Aqueductus Fallopii.
'Marrow cells.
,tion
the petrous and mastoid portions of the temporal bone, showing the communicati
of the cavity of the tympanum with the mastoid antrum.
Internal Surface. — The internal surface of the mastoid portion presents a deep,
curved groove, the sigmoid fossa or sulcus (sulcus sigmoideus), which lodges part
of the lateral sinus; and into it may be seen opening the mastoid foramen,
which transmits an emissary vein from the lateral sinus to the posterior auricular
or occipital vein and a small artery, the mastoid branch of the occipital artery
(ramus mastoideus). The groove for the lateral sinus is separated from the inner-
most of the mastoid air-cells by only a thin lamina of bone, and even this may be
partly deficient. A section of the mastoid process (Figs. 48 and 49) shows it to be
hollowed out into a number of cellular spaces, communicating with each other,
called the mastoid cells (cellulae mastoideae), which exhibit the greatest possible
variety as to their size and number, and which do not exist at birth, but develop
with the growth of the mastoid process. At the upper and front part of the
bone these cells are large and irregular, and contain air. They diminish in size
toward the lower part of the bone, those situated at the apex of the mastoid
process being quite small and usually containing marrow. These pneumatic
cells extend far beyond the mastoid. Some may reach the floor of the Eustachian
THE TEMPORAL BONE
87
canal; others the jugular portion of the occipital bone; others the roof of the
external auditory canal, and some pass up toward the squamous portion.1 Occa-
sionally they are entirely absent, and the mastoid is solid throughout. In addi-
tion to these pneumatic cells may be seen a large, irregular cavity (Figs. 48 and
49), situated at the upper and front part of the section. It is called the mastoid or
tympanic antrum (antrum tympanicum) , and must be distinguished from the mas-
toid cells, though it communicates with them. The mastoid cells are not developed
until after puberty, but the mastoid antrum is almost as large at birth as it is in
the adult.
It is filled with air, and is lined with a prolongation of the mucous membrane
of the tympanum, which extends into it through an opening, by which it com-
municates with the cavity of the tympanum. The mastoid antrum is bounded
above by a thin plate of bone, the tegmen tympani, which separates it from the
middle fossa of the base of the skull on the anterior surface of the petrous portion
PROMINENCE OVER
SEMICIRCULAR CANAL
FENESTRA OVALIS
OR VESTIBULI
PROCESSUS
COCHLEARIFORMIS
SEPTUM OF
EUSTACHIAN TUBE
PROBE IN
TYMPANIC
CANAL
SEMI CANAL FOR
TENSOR TYMPANI
PROBE IN
TYMPANIC CANAL
FIG. 49. — Right temporal bone cut open. Lateral view of medial half of bone. X 2. (Spalteholz.)
of the temporal bone ; below by the mastoid process ; externally by the squamous
portion of the bone just below the supramastoid crest; and internally by the
external semicircular canal of the internal ear, which projects into its cavity.
The opening by which it communicates with the tympanum is situated at the
superior internal angle of the posterior wall of that cavity; it is a triangular
ope.iing into that portion of the tympanic cavity which is known as the tu mptnic
attic or epitympanic recess or space (aditus ad antrum) — that is to say, that
portion of the tympanum which is above the level of the membrana tympani.
In consequence of the communication which exists between the tympanum and mastoid cells,
inflammation of the lining membrane of the former cavity may easily travel backward to that
of the antrum, leading to caries and necrosis of their walls and the risk of transference of the
inflammation to the lateral sinus or encephalon.
1 Dr. D. Kerfoot Shute, in Reference Handbook of the Medical Science's.
88 THE SKELETON
Borders. Superior Border. — The superior border of the mastoid portion is
broad and rough, its serrated edge sloping outward, for articulation with the
posterior inferior angle of the parietal bone.
Posterior Border. — The posterior border, also, uneven and serrated, articu-
lates with the inferior border of the occipital bone between its lateral angle and
jugular process.
The Petrous Portion of the Temporal Bone (Pars Petrosa [Pyramis]) (Fig. 47).
The petrous portion (nerpoz, a stone), so named from its extreme density and
hardness, is a pyramidal process of bone wedged in at the base of the skull
between the sphenoid and occipital bones. Its direction from without is inward,
forward, and a little downward. It presents for examination a base, an apex,
three surfaces, and three borders, and contains, in its interior, the essential parts
of the organ of hearing.
Base. — The base is applied against the internal surface of the squamous and
mastoid portions, its upper half being concealed; but its lower half is exposed
by the divergence of those two portions of the bone, which brings into view the
oval, expanded orifice of a canal leading 'into the tympanum, the meatus audi-
torius externus (meatus acusticus externus). The curved tympanic plate or part
(pars tympanica) forms the anterior wall, the floor, and a part of the posterior
wall of this meatus, while the squamous portion of the temporal completes it
above and behind. The entrance to the meatus is bounded throughout the
greater part of its circumference by the auditory process, which is the name
applied to the free rough margin of the tympanic plate, and which gives attach-
ment to the cartilaginous portion of the meatus. Superiorly the entrance to
the meatus is limited by the posterior root of the zygoma. At the upper and
posterior portion of the bony meatus is a spine of bone known as the suprameatal
spine or spine of Henle (spina suprameatum) , which is a valuable surgical land-
mark. In most skulls it is distinctly marked.
Apex (apex pyramidis). — The apex of the petrous portion, rough and uneven,
is received into the angular interval between the posterior border of the greater
wing of the sphenoid and the basilar process of the occipital; it presents the anterior
or internal orifice of the carotid canal (foramen caroticum internum), and forms
the posterior and external boundary of the foramen lacerum medium.
Surfaces. Anterior Surface (fades anterior pyramidis). — The anterior surface
of the petrous portion (Fig. 47) forms the posterior part of the middle fossa of
the skull. This surface is continuous with the squamous portion, to which it is
united by a suture, the petro-squamous suture, the remains of which are distinct even
at a late period of life. It presents six points for examination : (1) An eminence
(eminentia arcuata) near the centre, which indicates the situation of the
superior semicircular canal. (2) In front and a little to the outer side of this
eminence a depression indicating the position of the tympanum; here the layer
of bone which separates the tympanum from the cranial cavity is extremely thin,
and is known as the tegmen tympani. (3) A shallow groove, sometimes double,
leading outward and backward to an oblique opening, the hiatus Fallopii (hiatus
canalis facialis) , for the passage of the greater petrosal nerve and the petrosal
branch of the middle meningeal artery. (4) A smaller opening (apertura superior
canaliculi tympanici), occasionally seen external to the latter, for the passage of
the smaller petrosal nerve. (5) Near the apex of the bone, the termination of the
carotid canal, the internal carotid foramen (foramen caroticum internum), the wall
of which in this situation is deficient in front. (6) Above the canal a shallow
depression, the trigeminal depression (impressio trigemini), for the reception of the
Gasserian ganglion.
THE TEMPORAL BONE
89
Posterior Surface (fades posterior pyramidis), — The posterior surface forms the
front part of the posterior fossa of the skull, and is continuous with the inner
surface of the mastoid portion of the bone. It presents three points for exami-
nation: 1. About its centre, a large orifice, the meatus auditorius interims (meatus
acusticus interims), whose size varies considerably; its margins are smooth and
rounded, and it leads into a short canal, about four lines in length, which runs
directly outward and is closed by a vertical plate, the lamina cribrosa, which is
divided by a horizontal crest, the falciform crest (crista faldformis) , into two unequal
portions ( Fig. 50) . Each portion is subdivided by a little vertical crest into two parts,
named, respectively, anterior and posterior. The lower portion presents three sets
of foramina : one group just below the poste-
rior part of the crest, the area cribrosa media,
consisting of a number of small openings
for the nerves to the saccule; below and
posterior to this, the foramen singulare, or
opening for the nerve to the posterior semi-
circular canal ; in front and below the first,
the tractus spiralis foraminosus, consisting
of a number of small, spirally arranged
openings which terminate in the canalis
centralis cochleae and transmit the nerve to
the cochlea; the upper portion, that above
the crista, presents behind a series of small
openings the area cribrosa superior, for the
passage of filaments to the utricle and supe-
rior and external semicircular canal, and, in
front, one large opening, the commence-
ment of the aquseductus Fallopii (canalis
facialis), for the passage of the facial nerve.
2. Behind the rneatus auditorius, a small
slit (apertura externa aquceductus vestibuli),
almost hidden by a thin plate of bone, lead-
ing to a canal, the aquseductus vestibuli,
which transmits the ductus endolymphaticus
together with a small artery and vein. 3.
In the interval between these two openings, but above them, is an angular depres-
sion (fossa subarcuata) which lodges a process of the dura, and transmits a
small vein into the cancellous tissue of the bone. In the child this depression
is represented by a large fossa, the floccular fossa, which extends backward as a
blind tunnel under the superior semicircular canal.
Inferior Surface (fades inferior pyramidis) . — The inferior or basilar surface (Fig.
51) is rough and irregular, and forms part of the base of the skull. Passing from
the apex to the base, this surface presents eleven points for examination: 1. A
rough surface, quadrilateral in form, which serves partly for the attachment of
the Levator palati and Tensor tympani muscles. 2. The large, circular aperture
of the carotid canal, the external carotid foramen (foramen caroticum externum) ; the
canal ascends at first vertically, and then, making a bend, runs horizontally for-
ward and inward; it transmits the internal carotid artery and the carotid plexus.
Within the carotid canal are several openings (canaliculi carotico tympanici) which
transmit tympanic branches of the internal carotid artery and of the carotid plexus.
3. The opening of the aquaeductus cochleae (apertura externa canaliculi cochlea), a
small triangular opening, lying on the inner side of the latter, close to the posterior
and inner border of the petrous portion; it transmits a vein from the cochlea,
which joins the internal jugular. 4. Behind these openings a deep depression, the
FIG. 50. — Diagrammatic view of the fundus
of the internal auditory meatus: 1. Falciform
crest. 2. Anterior superior cribriform area. 2'.
Internal opening of the aqutcductus Fallopii.
3. Vertical crest which separates the anterior
and posterior superior cribriform areas. 4. Pos-
terior superior cribriform area, with (4') open-
ings for nerve-filaments. 5. Anterior inferior
cribriform area. 5'. Spirally arranged, sieve-like
openings for the nerves to the cochlea. 5". Open-
ing of the central canal of the cochlea. 6. Crest
which separates the anterior and posterior infe-
rior cribriform areas. 7. Posterior inferior crib-
riform area. 7'. Orifices for the branches of the
nerve to the saccule. 8. Foramen singulare of
Morgagni, with the anterior portion of the canal
which give^ passage to the nerve to the posterior
semicircular canal. (Testut)
90
THE SKELETON
jugular fossa (fossa jugularis], which varies in depth and size in different skulls; it
lodges the lateral sinus, and, with a similar depression on the margin of the jugular
process of the occipital bone, forms the foramen lacerum posterius or jugular fora-
men. 5. A foramen which is the opening of a small canal (canaliculus tympanicus},
Canals for Eustachian tube and
TENSOR TYMPANI MUSCLE.
Rough quadrilateral surface.
Opening of carotid canal.
Canal for Jacobson's nerve.
Aquseductus cochlese.
Canal for Arnold's nerve.
Jugular fossa.
Vaginal process.
Styloid process.
Stylo-mastoid foramen.
Jugular surface.
Auricular fissure.
STYLO-PHARYNQEU8.
^PB^^~
FIG. 51. — Petrous portion of the left temporal bone. Inferior surface.
for the passage of Jacobson's nerve (the tympanic branch of the glosso-pharyn-
geal); this foramen is seen in front of the bony ridge dividing the carotid canal
from the jugular fossa. 6. A small foramen on the wall of the jugular fossa, for
the entrance of the auricular branch of the vagus (Arnold's) nerve. 7. Behind
the jugular fossa a smooth, square-shaped facet, the jugular surface; it is covered
with cartilage in the recent state, and articulates with the jugular process of
the occipital bone. 8. The vaginal process (vagina processus styloidea], a very
broad, sheath-like plate of bone, which extends backward from the carotid canal,
gives attachment to part of the Tensor palati muscle; this plate divides behind
into two laminae, the outer of which is continuous with the tympanic plate, the
inner with the jugular process. 9. Between these laminae is the ninth point for
examination, the styloid process (processus styloideus}, a sharp spine, about an
inch in length; it is directed downward, forward, and inward, varies in size and
shape, and sometimes consists of several pieces united by cartilage; it affords
attachment to three muscles, the Stylo-pharyngeus, Stylo-hyoideus, and Stylo-
glossus, and two ligaments, the stylo-hyoid and stylo-maxillary. 10. The stylo-
mastoid foramen (foramen stylomasloideum], a rather large orifice, placed between
the styloid and mastoid processes; it is the termination of the aquseductus Fallopii,
and transmits the facial nerve and stylo-mastoid artery. 11. The auricular fissure
(fissura tympanomasloidea), situated between the tympanic plate and mastoid
process, for the exit of the auricular branch of the vagus nerve. This fissure is the
THE TEMPORAL BONE
91
external opening of the canaliculus mastoideus, which passes to the aqueduct of
Fallopius.
Borders. Superior Border (angulus superior pyramidis}. — The superior, the
longest, is grooved for the superior petrosal sinus, and has attached to it the ten-
torium; at its inner extremity is a semilunar notch, upon which the trigeminal
nerve lies.
Posterior Border (angulus posterior pyramidis} . — The posterior border is inter-
mediate in length between the superior and the anterior. Its inner half is marked
by a groove, which, when completed by its articulation with the occipital, forms
the channel for the inferior petrosal sinus. Its outer half presents a deep excava-
tion, the jugular fossa (fossa jugularis), which, with a similar notch on the occipital,
forms the foramen lacerum posterius. A projecting eminence of bone occasionally
stands out from the centre of the notch, and divides the foramen into two parts.
Anterior Border (angulus anterior pyramidis) . — The anterior border is divided
into two parts — an outer, joined to the squamous portion by a suture, the remains
of which are distinct; an inner, free, articulating with the spinous process of the
sphenoid. At the angle of junction of the petrous and squamous portions is
seen the opening of the canalis musculotubarius. This canal is completely or
partially divided into two canals, separated from one another by a thin plate of
bone, the processus cochleariformis (septum canalis musculotubarii) ; they both lead
into the tympanum, the upper one (semicanalis m. tensoris tympani} transmitting
the Tensor tympani muscle, the lower
one (semicanalis tubce auditivce) form-
ing the bony part of the Eustachian
tube or canal.
Structure. — The squamous portion
is like that of the other cranial bones:
the mastoid portion, cellular; and the
petrous portion, dense and hard.
Development (Fig. 52). — The tem-
poral bone is developed by ten centres, 1 for tympanic
exclusive of those for the internal ear
and the ossicula — viz., one of the
squamous portion including the zygo-
ma, one for the tympanic plate, six for
the petrous and mastoid parts, and two
for the styloid process. Just before the
close of foetal life the temporal bone
consists of four parts: 1. The squamo-
zygomatic part, ossified in membrane
from a single nucleus, which appears
If or
squamous
portion,
including
zygoma :
2d month.
plate.
6 for petrous
and mastoid
portions.
2 for styloid process.
By
FIG. 52. — Development of the temporal bone,
ten centres.
at its lower part about the second
month. 2. The tympanic plate, an imperfect ring, in the concavity of which is
a groove, the sulcus tympanicus, for the attachment of the circumference of the
tympanic membrane. This is also ossified from a single centre, which appears
about the third month. 3. The petro -mastoid part is developed from six cen-
tres, which appear about the fifth or sixth month. Four of these are for the
petrous portion, and are placed around the labyrinth, and two for the mastoid
(Vrolik). According to Huxley, the centres are more numerous, and are dis-
posed so as to form three portions: (1) including most of the labyrinth, with a
part of the petrous and mastoid, he has named prootic; (2) the rest of the petrous,
the opisthotic; and (3) the remainder of the mastoid, the epiotic. The petro-
mastoid is ossified in cartilage. 4. The styloid process is also ossified in cartilage
from two centres: one for the base, which appears before birth, and is termed the
92 THE SKELETON
tympanohyal; the other, comprising the rest of the process, is named the stylohyal,
and does not appear until after birth. Shortly before birth the tympanic plate joins
with the squarnous. The petrous and mastoid join with the squamous during
the first year, and the tympanohyal portion of the styloid process about the same
time. The stylohyal does not join the rest of the bone until after puberty, and
in some skulls never becomes united. The subsequent changes in this bone are,
that the tympanic plate extends outward and backward, so as to form the meatus
auditorius. The extension of the tympanic plate, however, does not take place at
an equal rate all around the circumference of the ring, but occurs most rapidly
on its anterior and posterior portions, and these outgrowths meet and blend, and
thus, for a time, there exists in the floor of the meatus a foramen, the foramen of
Huschke; this foramen may persist throughout life. The glenoid cavity is at first
extremely shallow, and looks outward as well as downward; it becomes deeper
and is ultimately directed downward. Its change in direction is accounted for
as follows: the part of the squamous temporal which supports it lies at first below
the level of the zygoma. As, however, the base of the skull increases in width,
this lower part of the squama is directed horizontally inward to contribute to
the middle fossa of the skull, and its surfaces therefore come to look upward and
downward. The mastoid portion is at first quite flat, and the stylo-mastoid fora-
'men and rudimentary styloid process lie immediately behind the entrance to the
auditory meatus. With the development of the air-cells the outer part of the
mastoid portion grows downward and forward to form the mastoid process, and
the styloid process and stylo-mastoid foramen now come to lie on the under sur-
face. The descent of the foramen is necessarily accompanied by a corresponding
lengthening of the aqueduct of Fallopius.
The downward and forward growth of the mastoid process also pushes forward
the tympanic plate, so that the portion of it which formed the original floor of
the meatus and containing the foramen of Huschke is ultimately found in the
anterior wall. With the gradual increase in size of the petrous portion the floc-
cular fossa or tunnel under the superior semicircular canal becomes filled up
and almost obliterated.
Articulations. — With five bones — occipital, parietal, sphenoid, inferior maxil-
lary, and malar.
Attachment of Muscles. — To fifteen : to the squamous portion, the Tem-
poral; to the zygoma, the Masseter; to the mastoid portion, the Occipito-
frontalis, Sterno-mastoid, Splenius capitis, Trachelo-mastoid, Digastricus, and
Retrahens aurem; to the styloid process, the Stylo-pharyngeus, Stylo-hyoideus,
and Stylo-glossus ; and to the petrous portion, the Levator palati, Tensor
tympani, Tensor palati, and Stapedius.
The Sphenoid Bone (Os Sphenoidale) .
The sphenoid bone (oyyv, a wedge) is situated at the anterior part of the base
of the skull, articulating with all the other cranial bones, which it binds firmly
and solidly together. In its form it somewhat resembles a bat with its wings
extended; and is divided into a central portion or body, two greater and two lesser
wings extending outward on each side of the body, and two processes — the ptery-
goid processes — which project from it below.
The Body of the Sphenoid Bone.
The body (corpus) is of large size and hollowed out in its interior so as to form a
mere shell of bone. It presents for examination four surfaces — a superior, an
inferior, an anterior, and a posterior.
THE SPHENOID BONE
93
Surfaces. Superior Surface (fades cerebralis) (Fig. 53). — In front is seen a promi-
nent spine, the ethmoidal spine, for articulation with the cribriform plate of the eth-
moid ; behind this a smooth surface presenting, in the median line, a slight longi-
tudinal eminence, with a depression on each side for lodging the olfactory lobes.
This surface is bounded behind by a ridge, which forms the anterior border of a
narrow, transverse groove, the optic groove (sulcus chiasmatis), behind which lies the
optic chiasm; the groove is continuous on each side with the optic foramen (foramen
opticum) , for the passage of the optic nerve and ophthalmic artery. Behind the
Middle cJnioid process. Ethmoidal
_ Posterior dinoid process. \ „_ .,_ spine.
Foramen opticum.
Foramen lacerum anie-
rius or Sphenoidal
fissure.
Foramen rotundum.
Foramen Vesalii;
Foramen orate:
Foramen .spinosum.
FIG. 53. — Sphenoid bone. Superior surface.
optic groove is a small eminence, olive-like in shape, the olivary process or eminence
(tuberculum sellce) ; and still more posteriorly, a deep depression, the pituitary fossa,
or sella turcica (fossa hypophyseos) , which lodges the circular sinus and the pituitary
body (hypophysis). This fossa is perforated by numerous foramina, for the trans-
mission of nutrient vessels into the substance of the bone. It is bounded in front
by the olivary eminence, and also by two small eminences, one on either side, called
the middle clinoid processes (processus clinoidei medii) (xkivq, a bed), which are
sometimes connected by a spiculum of bone to the anterior clinoid processes. It
is bounded behind by a square-shaped plate of bone, the dorsum ephippii or dorsum
sellae, terminating at each superior angle in a tubercle, the posterior clinoid process
(processus clinoideus posterior) . The size and form of these processes vary con-
siderably in different individuals. They deepen the pituitary fossa, and serve for
the attachment of prolongations from the tentorium. The sides of the dorsum
ephippii are notched for the passage of the abducent nerves, and below present
a sharp process, the petrosal process, which is joined to the apex of the petrous
portion of the temporal bone, forming the inner boundary of the middle lacerated
foramen. Behind this plate the bone presents a shallow depression, which slopes
obliquely backward, and is continuous with the basilar groove of the occipital
bone; it is called the clivus, and supports the upper part of the pons. On either
side of the body is a broad groove, curved something like the italic letter /; it
lodges the internal carotid artery and the cavernous sinus, and is called the carotid
or cavernous groove (sulcus caroticus). Along the outer margin of this groove,
at its posterior part, is a ridge of bone in the angle between the body and greater
wing, called the lingula (lingula sphenoidalis).
Posterior Surface. — The posterior surface, quadrilateral in form, is joined to the
basilar process of the occipital bone. During childhood these bones are separated
94
THE SKELETON
by a layer of cartilage; but in after-life (between the eighteenth and twenty-fifth
years) this becomes ossified, ossification commencing above and extending down-
ward; and the two bones then form one piece.
Anterior Surface. — The anterior surface (Fig. 54) presents, in the middle line, a
vertical ridge of bone, the ethmoidal or sphenoidal crest (crista sphenoidalis) , which
articulates in front with the perpendicular plate of the ethmoid, forming part of
the septum of the nose. On either side of it are irregular openings leading into
the sphenoidal cells or sinuses (sinus sphenoidales) . These are two large, irregular
cavities hollowed out of the interior of the body of the sphenoid bone, often
'erygo- \ \Artic. with
ine I \ vomer.
ma/. '
Groove for alal
of vomer. 7
m~S
Pterygoid ridge.
Internal pterygoid plate.-
Hamular process.-
FIG. 54. — Sphenoid bone. Anterior surface.1
extending into the pterygoid processes and base of the greater wings of the bone,
and separated from one another by a more or less complete perpendicular bony
septum (septum sinuum sphenoidalium) . Occasionally they extend into the basilar
process of the occipital nearly as far as the foramen magnum. Their form and
size vary considerably; they are seldom symmetrical, and are often partially sub-
divided by irregular, osseous lamime. One sinus or both sinuses may be absent.
The septum is seldom quite vertical, being commonly bent to one or the other
side. These sinuses do not exist in very young children, but appear, according
to Laurent, in the seventh year, and, according to Tillaux, not until the twen-
tieth year. After once appearing they increase in size as age advances. They
are partially closed, in front and below, by two thin, curved plates of bone,
the sphenoidal, spongy, or turbinated bones (conches sphenoidales}. At the upper
part of each is a round opening (apertura sinus sphenoidalis) by which the sinus
communicates with the upper and back part of the nose, and occasionally with
the posterior ethmoidal cells or sinuses. The lateral margins of this surface
present a serrated edge, which articulates with the os planum of the ethmoid,
completing the posterior ethmoidal cells; the lower margin, also rough and ser-
rated, articulates with the orbital process of the palate bone, and the upper
margin with the orbital plate of the frontal bone.
Inferior Surface. — The inferior surface presents, in the middle line, a triangular
spine, the rostrum (rostrum sphenoidalis), which is continuous with the sphenoidal
crest on the anterior surface, and is received into a deep fissure between the alae
1 In this ficcure, both the anterior and inferior surfaces of the body of the sphenoid bone are shown, the bone
being held with the pterygoid processes almost horizontal. — ED. of 15th English Edition.
THE SPHENOID BONE 95
of the voraer. On each side may be seen a projecting lamina of bone, which runs
horizontally inward from near the base of thepterygoid process: these plates, termed
the vaginal processes, articulate with the edges of the vomer. Close to the root of
the pterygoid process is a groove (sidcus pterygopalatinus) , formed into a complete
canal when articulated with the sphenoidal process of the palate bone ; it is called
the pterygo-palatine canal, and transmits the pterygo-palatine vessels and pharyngeal
nerve.
The Greater or Temporal Wings of the Sphenoid Bone (Alae Magnae ) .
The greater wings are two strong processes of bone which arise from the sides
of the body, and are curved in a direction upward, outward, and backward, each
being prolonged behind into a sharp-pointed extremity, the alar or sphenoidal
spine (spina angularis) . Each wing presents three surfaces and a circumference.
Surfaces. Superior Surface (fades cerebralis). — The superior or cerebral surface
(Tig. 53) forms part of the middle fossa of the skull; it is deeply concave, and pre-
sents eminences and depressions for the convolutions of the brain. At its anterior
and internal part is seen a circular aperture, the foramen rotundum, for the transmis-
sion of the second division of the trigeminal nerve. Behind and external to this is a
large, oval foramen, the foramen ovale, for the transmission of the third division of
the trigeminal nerve, the small meningeal artery, and sometimes the small petrosal
nerve.1 At the inner side of the foramen ovale a small aperture may occasionally
be seen opposite the root of the pterygoid process; it is the foramen Vesalii, trans-
mitting a small vein. Lastly, in the posterior angle, near to the spine of the sphe-
noid, is a short canal, sometimes double, the foramen spinosum; it transmits the
middle meningeal artery.
External Surface. — The external surface (Fig. 54) is convex and divided by a
transverse ridge, the pterygoid ridge or infratemporal crest (crista infratemporalis) ,
into two portions. The superior or larger, convex from above downward, concave
from before backward, enters into the formation of the temporal fossa, and gives
attachment to part of the Temporal muscle. The inferior portion, smaller in size
and concave, enters into the formation of the zygomatic fossa, and affords attach-
ment to the External pterygoid muscle. It presents, at its posterior part, a sharp-
pointed eminence of bone, the spine, to which are connected the internal lateral
ligament of the lower jaw and the Tensor palati muscle. The pterygoid ridge,
dividing the temporal and zygomatic portions, gives attachment to part of the
External pterygoid muscle. At its inner and anterior extremity is a triangular
spine of bone, which serves to increase the extent of origin of this muscle.
Anterior Surface (fades orbitalw] . — The anterior or orbital surface, smooth and
quadrilateral in form, assists in forming the outer wall of the orbit. It is bounded
above by a serrated edge, for articulation with the frontal bone; below, by a rounded
border which enters into the formation of the spheno-maxillary fissure. Internally, it
presents a sharp border, which forms the lower boundary of the sphenoidal fissure,
and has projecting from about its centre a little tubercle of bone, which gives
origin to one head of the External rectus muscle of the eye; and at its upper part
is a notch for the transmission of a recurrent branch of the lachrymal artery;
externally it presents a serrated margin for articulation with the malar bone. One
or two small foramina may occasionally be seen for the passage of branches of
the deep temporal arteries; they are called the external orbital foramina.
Circumference (Fig. 53). — Commencing from behind, that portion of the cir-
cumference from the body of the sphenoid to the spine is serrated and articulates
by its outer half with the petrous portion of the temporal bone, while the inner
half forms the anterior boundary of the foramen lacerum medium, and presents
1 The small petrosal nerve sometimes passes through a special forame j between the foramen ovale and foramen
spinosum. — ED. of 15th English Edition.
96 THE SKELETON
the. posterior aperture of the Vidian canal (canalis pterygoideus) for the passage of the
Vidian nerve and artery. In front of the spine, the circumference of the great wing
presents a serrated edge, bevelled at the expense of the inner table below and of the
external above, which articulates with the squamous portion of the temporal bone.
At the tip of the great wing a triangular portion is seen, bevelled at the expense of
the internal surface, for articulation with the anterior inferior angle of the parietal
bone. Internal to this, is a triangular, serrated surface, for articulation with the
frontal bone; this surface is continuous internally with the sharp inner edge of
the orbital plate, which assists in the formation of the sphenoidal fissure, and
externally with the serrated margin for articulation with the malar bone.
The Lesser or Orbital Wings of the Sphenoid Bone (Alse Parvse).
The lesser wings (processes of Ingrassias) are two thin, triangular plates of
bone which arise from the upper and lateral parts of the body of the sphenoid,
and, projecting transversely outward, terminate in a sharp point (Fig. 53). The
superior surface of each is smooth, flat, broader internally than externally, and
supports part of the frontal lobe of the brain. The inferior surface forms the
back part of the roof of the orbit and the upper boundary of the orbital or sphe-
noidal fissure or foramen lacerum anterius (fissura orbitalis superior) . This fissure is
of a triangular form, and leads from the cavity of the cranium into the orbit; it is
bounded internally by the body of the sphenoid — above, by the lesser wing;
below, by the internal margin of the orbital surface of the great wing — and is
converted into a foramen by the articulation of this bone with the frontal. It
transmits the third, the fourth, the three branches of the ophthalmic division
of the trigeminal, the abducent nerve, some filaments from the cavernous plexus
of the sympathetic, the orbital branch of the middle meningeal artery, a recur-
rent branch from the lachrymal artery to the dura and the ophthalmic vein.
The anterior border of the lesser wing is serrated for articulation with the
frontal bone; the posterior border, smooth and rounded, is received into the fissure of
Sylvius of the brain. Each inner extremity of this border forms an anterior clinoid
process (processus clinoideus anterior). The lesser wing is connected to the side
of the body by two roots, the upper thin and flat, the lower thicker, obliquely
directed, and presenting on its outer side, near its junction with the body, a small
tubercle, for the attachment of the common tendon of origin of three of the muscles
of the eye. Between the two roots is the optic foramen (foramen opticum), for
the transmission of the optic nerve and ophthalmic artery.
The Pterygoid Processes of the Sphenoid Bone (Processus Pterygoidei) .
The pterygoid processes (xrepus, a wing; e?&>c, likeness), one on each side,
descend perpendicularly from the point where the body and greater wing unite
(Fig. 55). Each process consists of an external and an internal lamina or plate,
which are joined together by their anterior borders above, but are separated below,
leaving an angular cleft, the pterygoid notch or fissure (fissura pterygoidea) , in which
the pterygoid process or tuberosity of the palate bone is received. The two plates
diverge from each other from their line of connection in front, so as to form a V--
shaped fossa, the pterygoid fossa (fossa pterygoidea) . The external pterygoid plate
(lamina later alls processus pterygoidei) is broad and thin, turned a little outward,
and, by its outer surface, forms part of the inner wall of the zygomatic fossa, giving
attachment to the External pterygoid ; its inner surface forms part of the pterygoid
fossa, and gives attachment to the Internal pterygoid. The internal pterygoid plate
(lamina medialis processus pterygoidei) is much narrower and longer, curving
outward, at its extremity, into a hook-like process of bone, the hamular process
THE SPHENOID BONE
97
(hamulus pterygoideus}, around which turns the tendon of the Tensor palati
muscle. The outer surface of this plate forms part of the pterygoid fossa, the
inner surface forming the outer boundary of the posterior aperture of the nares.
On the posterior surface of the base of the process, above the pterygoid fossa, is a
small, oval, shallow depression, the scaphoid fossa (fossa scaphoidea), from which
arises the Tensor palati, and above which is seen the posterior orifice of the Vidian
canal (canal is pterygoideus [Vidii]). Below and to the inner side of the Vidian
FIG. 55. — Sphenoid bone. Posterior surface.
canal, on the posterior surface of the base of the internal plate, is a little promi-
nence, which is known by the name of the pterygoid tubercle. The Superior
constrictor of the pharynx is attached to the posterior edge of the internal plate.
The anterior surface of the pterygoid process is very broad at its base, and forms
the posterior wall of the spheno-maxillary fossa. It supports Meckel's ganglion.
It presents, above, the anterior orifice of the Vidian canal ; and below, a rough
margin, which articulates with the perpendicular plate of the palate bone.
The Sphenoidal Spongy Bone.
The sphenoidal spongy, turbinal or turbinated bones (the bones of Bertin, conches
sphenoidales) are two thin, curved plates of bones, which exist as separate pieces
until puberty, and occasionally are not joined to the sphenoid in the adult. They
are situated at the anterior and inferior part of the body of the sphenoid, an
aperture (apertura sinus sphenoidalis) of variable size being left in the anterior wall
of each, through which the sphenoidal sinuses open into the nasal fossae. They are
irregular in form and taper to a point behind, being broader and thinner in front.
Their upper surface, which looks toward the cavity of the sinus, is concave; their
under surface convex. Each bone articulates in front with the ethmoid, exter-
nally with the palate; its pointed posterior extremity is placed above the vom^r,
and is received between the root of the pterygoid process on the outer side and
the rostrum of the sphenoid on the inner.1
Development. — Up to about the eighth month of fcetal life the sphenoid bone
consists of two distinct parts: a posterior or post-sphenoid part, which comprises
the pituitary fossa, the greater wings, and the pterygoid processes; and an anterior
or pre-sphenoid part, to which the anterior part of the body and lesser wings
belong. It is developed by fourteen centres: eight for the posterior sphenoid
division, and six for the anterior sphenoid. The eight centres for the posterior
1 A small portion of the sphenoidal turbinated bone sometimes enters into the formation of the inner wall of
the orbit, between the os planum of the ethmoid in front, the orbital plate of the palate below, and the frontal
above.— Cleland, Roy. Soc. Trans.. 1862.
98 THE SKELETON
sphenoid are: one for each greater wing and external pterygoid plate, one for
each internal pterygoid plate, two for the posterior part of the body, and one on
each side for the lingula. The six for the anterior sphenoid are: one for each
lesser wing, two for the anterior part of the body, and one for each sphenoidal
turbinated bone.
Post-sphenoid Division. — The first nuclei to appear are those for the greater
wings (ali-sphenoids). They make their appearance between the foramen rotun-
dum and foramen ovale about the eighth
one for each two for anterior week, and from them the external ptervgoid
lesser wing, gart of body. pjates are a]so formed. Soon after, the
nuclei for the posterior part of the body
appear, one on either side of the sella turcica,
and become blended together about the
middle of foetal life. About the fourth
month the remaining four centres appear,
one for each inte^alA'?'' ^ \ tho.se for ; the" internal pterygoid plates being
pterygoid plate. ''•' \ ossified in membrane and becoming joined
one for for°each lingula. \ to the external pterygoid plate about the
each great wing and external ptery- sixth month. The centres for the Ungulte
one for each Sphenoidal turbinated bSedplate' speedily become joined to the rest of the
FIG. 56. — Plan of development of the sphenoid.
By fourteen centres. Pre-sphenoid Division. — The first nuclei
to appear are those for the lesser wings
(orbito-sphenoids). They make their appearance about the ninth week, at the
outer borders of the optic foramina. A second pair of nuclei appear on the inner
side of the foramina shortly after, and, becoming united, form the front part of
the body of the bone. The remaining two centres for the sphenoidal turbinated
bones make their appearance about the fifth month. At birth they consist of small
triangular laminae, and it is not till the third year that they become hollowed out
and cone-shaped. About the fourth year they become fused with the lateral
masses of the ethmoid, and hence, from an embryo logical point of view, may be
regarded as belonging to the ethmoid.
The pre-sphenoid is united to the body of the post-sphenoid about the eighth
month, so that at birth the bone consists of three pieces — viz., the body in the
centre, and on each side the great wings with the pterygoid processes. The lesser
wings become joined to the body at about the time of birth. At the first year
after birth the greater wings and body are united. From the tenth to the twelfth
year the spongy bones are partially united to the sphenoid, their junction being
complete by the twentieth year. Lastly, the sphenoid joins the occipital from the
eighteenth to the twenty-fifth year.
Articulations. — The sphenoid articulates with all the bones of the cranium,
and five of the face— the two malar, the two palate, and vomer; the exact extent
of articulation with each bone is shown in the accompanying figures.1
Attachment of Muscles. — To eleven pairs: the Temporal, External ptervgoid,
Internal pterygoid, Superior constrictor, Tensor palati, Levator palpebrse, Ob-
liquus oculi superior, Superior rectus, Internal rectus, Inferior rectus, External
rectus.
The Ethmoid Bone (Os Ethmoidale).
The ethmoid (/}#//oc, a sieve) is an exceedingly light, spongy bone, of a cubical
form, situated at the anterior part of the base of the cranium, between the two
orbits at the root of the nose, and contributing to form each of these cavities.
1 It also sometimes articulates with the tuberosity of the superior maxilla. — ED. of 15th English Edition.
THE ETHMOID BONE
99
It consists of three parts: a horizontal plate, which forms part of the base of the
cranium; a perpendicular plate, which forms part of the septum nasi; and two
lateral masses of cells.
The Horizontal Lamina or Cribriform Plate (lamina cribrosa) (Fig. 57) forms
part of the anterior fossa of the base of the skull, and is received into the ethmoid
notch of the frontal bone be-
tween the two orbital plates.
Projecting upward from the
middle line of this plate is a
thick, smooth, triangular pro-
cess of bone, the crista galh', so
called from its fancied resem-
blance to a cock's comb. Its
base joins the cribriform plate.
Its posterior border, long, thin,
and slightly curved, serves for
the attachment of the falx.
Its anterior border, short and
thick, articulates with the
frontal bone, and presents two
small projecting alse (processus
alares] , which are received in- mth inferior lurbinated b~°™-
to corresponding depressions
in the frontal, completing the
foramen caecum behind. Its sides are smooth and sometimes bulging; in which
case it is found to enclose a small sinus.1 On each side of the crista galli the cribri-
form plate is narrow and deeply grooved, to support the bulb of the olfactory tract,
and is perforated by foramina for the passage of the olfactory nerves. These fora-
FIG. 57. — Ethmoid bone. Outer surface of right lateral mass
(enlarged).
LAMINA CRIBROSA
CRISTA GALLI
ALAR PROCESS
LAMINA CRIBROSA
UNCIFORM
PROCESS
ETHMOIDAL PERPENDICU-
LABYRINTH LAR LAMINA
FIG. 58. — Ethmoid bone from behind, somewhat
schematic. (Spalteholz.)
POSTERIOR
ETHMOIDAL
FORAMEN
ANTERIOR
ETHMOIDAL
FORAMEN
CRISTA GALLI
ALAR PROCESS
FIG. 59. — Ethmoid bone from above. (Spalteholz.)
mina are arranged in three rows: the innermost, which are the largest and least
numerous, are lost in grooves on the upper part of the septum; the foramina of the
outer row are continued on to the surface of the upper spongy bone. The fora-
mina of the middle row are the smallest; they perforate the bone and transmit
nerves to the roof of the nose. At the front part of the cribriform plate, on each
1 Sir George Humphry states that the crista galli is commonly inclined to one side, usually the opposite to
that toward which the lower part of the perpendicular plate is bent. — The Human Skeleton, 1858, p. 277.
100
THE SKELETON
with Ethmoidal
side of the crista galli, is a small fissure, which transmits the nasal branch of the
ophthalmic nerve; and at its posterior part a triangular notch, which receives the
ethmoidal spine of the sphenoid.
The Vertical or Perpendicular Lamina or Plate (lamina perpendicular™ or
mesethmoid) (Fig. 60) is a thin, flattened lamella of bone, which descends from the
under surface of the cribriform plate, and assists in forming the septum of the nose.
It is much thinner in the middle than at the circumference, and is generally deflected
a little to one side. Its anterior border articulates with the nasal spine of the frontal
bone and crest of the nasal bones. Its posterior border, divided into two parts,
articulates by its upper
half with the sphenoidal
crest of the sphenoid, by
its lower half with the
vomer. The inferior bor-
der serves for the attach-
ment of the triangular car-
tilage of the nose. On
each side of the perpen-
dicular plate numerous
grooves and canals are
seen, leading from the for-
amina on the cribriform
plate; they lodge filaments
of the olfactory nerves.
The Lateral Mass or
Labyrinth (labyrinthus
ethmoidalis) of the ethmoid
consists of a number of
thin-walled cellular cavities, the ethmoidal cells (cellulw ethmoidales) interposed be-
tween two vertical plates of bone, the outer one of which forms part of the orbit,
and the inner one part of the nasal fossa of the corresponding side. There are two
lateral masses, one on each side. The ethmoidal cells are not present at birth,
but appear during the fifth year. In the disarticulated bone many of these cells
appear to be broken; but when the bones are articulated they are closed in at
every part, except where they open into the nasal fossse. The upper surface of
each lateral mass presents a number of apparently half-broken cellular spaces;
these are closed in, when articulated, by the edges of the ethmoidal notch of the
frontal bone. Crossing this surface are two grooves on each side, converted into
canals by articulation with the frontal; they are the anterior and posterior ethmoidal
canals (canalis ethmoidale anterius and posterius), and open on the inner wall of
the orbit. The posterior surface also presents large, irregular cellular cavities,
which are closed in by articulation with the sphenoidal turbinated bones and
the orbital process of the palate. The cells at the anterior surface are completed
by the lachrymal bone and nasal process of the superior maxillary, and those
below also by the superior maxillary. The outer surface of each lateral mass is
formed of a thin, smooth, oblong plate of bone, called the os planum (lamina
papyracea) ; it forms part of the inner wall of the orbit, and articulates, above,
with the orbital plate of the frontal; below, with the superior maxillary; in
front, with the lachrymal; and behind, with the sphenoid and orbital process of
the palate.
From the inferior part of each lateral mass, immediately beneath the os planum,
there projects downward and backward an irregular lamina of bone, called the
unciform process (processus uncinatus), from its hook-like form; it serves to close
in the upper part of the orifice of the antrum, and articulates with the ethmoidal
FIG. 60. — Perpendicular plate of ethmoid (enlarged), shown by
removing the right lateral mass.
THE ETHMOID BONE 101
process of the inferior turbinated bone. It, is often broken in disarticulating the
bones.
The inner surface of each lateral mass forms part of the outer wall of the nasal
fossa of the corresponding side. It is formed of a thin lamella of bone, which
descends from the under surface of the cribriform plate, and terminates below in
a free, convoluted margin, the middle turbinated or the inferior ethmoidal turbinate
bone (concha nasalis media). The middle turbinated bone may contain a cell or
cells, which are really ethmoidal cells. Howard A. Lothrop1 studied 1000 speci-
mens, and found cells in 9 per cent,
of them. He never found cells in
children. As a rule, a turbinate cell
communicates with a posterior eth-
moidal cell, but may join an anterior
ethmoidal cell. The cells may open
into the superior meatus or into the
middle meatus. The whole of this
surface is rough and marked above
by numerous grooves, which run nearly
vertically downward from the cribri-
form plate; they lodge branches of the
IP i • i !• . -i j FIG. 61. — Ethmoid bone. Inner surface of right lateral
olfactory nerve, which are distributed mass (enlarged).
on the mucous membrane covering the
bone. The back part of this surface is subdivided by a narrow oblique fissure, the
superior meatus of the nose (meatus nasi superior) , bounded above by a thin, curved
plate of bone, the superior turbinated bone (concha nasalis superior}. By means of an
orifice at the upper part of this fissure the posterior ethmoidal cells open into the
superior meatus. Below, and in front of the superior meatus, is seen the convex sur-
face of the middle turbinated bone. It extends along the whole length of the inner
surface of each lateral mass; its lower margin is free and thick, and its concavity,
directed outward, assists in forming the middle meatus. It is by a large orifice
at the upper and front part of the middle meatus that the anterior ethmoidal cells,
and through them the frontal sinuses, communicate with the nose by means of a
funnel-shaped canal, the infundibulum (infundibulum ethmoidale). The cellular
cavities of each lateral mass, thus walled in by the os planum on the outer side and
by the other bones already mentioned, are divided by a thin transverse bony parti-
tion into two sets, which do not communicate with each other; they are termed
the anterior and posterior ethmoidal cells or sinuses. The former, more numerous,
communicate with the frontal sinuses above and the middle meatus below by
means of a long, flexuous canal, the infundibulum; the posterior, less numerous,
open into the superior meatus and communicate (occasionally) with the sphe-
noidal sinuses. In some cases the ethmoidal sinuses communicate with the maxil-
lary sinus. In some cases the os planum never develops, and the ethmoidal
sinuses are separated from the orbit merely by membrane.
Development. — By three centres: one for the perpendicular lamella, and one
for each lateral mass. The lateral masses are first developed, ossific granules
making their appearance in the os planum between the fourth and fifth months
of fretal life, and extending into the spongy bones. At birth the bone consists of
the two lateral masses, which are small and ill-developed. During the first year
after birth the perpendicular plate and crista galli begin to ossify, from a single
nucleus, and become joined to the lateral masses about the beginning of the second
year. The cribriform plate is ossified partly from the perpendicular plate and
partly from the lateral masses. The formation of the ethmoidal cells, which com-
pletes the bone, does not commence until the end of the fourth year.
1 Annals of Surgery, May, 1903.
102 THE SKELETON
Articulations. — With fifteen bones: the sphenoid, two sphenoidal turbinated,
the frontal, and eleven of the face — the two nasal, two superior maxillary, two
lachrymal, two palate, two inferior turbinated, and the vomer. No muscles are
attached to this bone.
DEVELOPMENT OF THE CRANIUM.
The cerebral vesicles became enclosed by an envelope of membrane derived from the em-
bryonic connective tissue about the head end of the chorda. This sac from the mesoderm
is converted into fibrous tissue, and is known -as the membranous cranium. In adult life
the dura mater represents the membranous cranium.
In mammals the base and part of the sides of the membranous cranium become cartilaginous,
but the roof and the remaining part of the sides remain membranous. Ossification com-
mences in the roof and begins at a later period in the base. Although ossification begins in
the membrane bones before it does in the cartilage bones, and the bones of the roof appear
before the bones of the base and make considerable progress in their growth, at birth ossification
is more advanced in the base, this portion of the skull forming a solid, immovable groundwork.
The Skull at Different Ages. — The skull at birth is relatively of large size as compared
with the body. The cerebral cranium is large and the face is small. The fontanelles are
open (see below). There are no sutures, but the margins of adjacent bones are widely sepa-
rated by fibrous tissue which runs from the periosteum to the dura mater. The bones of the
vault have no diploe and digital impressions are absent on the cranial surfaces. The parietal
eminences and the frontal eminences are very distinct.1
The orbits and parietal bones are large. If the base is examined it is noted that the
mastoid processes are absent, that the lower border of the symphysis of the jaw is on a level
with the condyles of the occipital bone, and that the pterygoid plates form " a large angle with
the skull base, whereas in the adult the angle is almost a right one," 2 The lower jaw at birth
is shown in Fig. 91 .
The development of individual bones is considered under the appropriate headings. At
puberty various pneumatic cells develop in bone and alter the form of the head and face.
After the eruption of the first set of teeth the age can be determined with reasonable cer-
tainty, and the degree of obliteration of the sutures will also give valuable information. In
the vast majority of individuals the metopic suture becomes a mere trace during the fifth or
sixth years. Ossification at the junction of the coronal and sagittal sutures and osseous union
of the sphenoid and basilar portion of the occipital occur during maturity. The lower jaw of
an adult is shown in Fig. 93. 7
In old age much of the diploe disappears and the bones become thinner and more porous.
The alveolar surfaces of the jaws are absorbed if the teeth are lost, and the lower jaw alters
its form (Fig. 94).
Sexual Differences. — It is not always possible to tell with certainty a woman's skull from
a man's, but certain features are of value in reaching a conclusion. Virchow maintained that
in non-European races it is very difficult to determine the sex from the skull, though among
some savage races the differences may be great.3 It is always to be borne in mind that a
woman's skull may be of the masculine type and a man's skull may be of the feminine type.
There is no constant characteristic significant of the male or female skull. As a general rule,
the female skull is smaller and lighter than the male; the muscular ridges and processes
are less distinct, the mastoid processes are of less size, the orbital margins are thin and
sharp, the forehead is more vertical and the vertex is more flattened, and the edge
of the tympanic plate is " rounder and more tuberculous " (Cunningham). The frontal
air sinuses are smaller in women than in men, one reason why the glabella is more promi-
nent in men. The flattening of the vertex in women, previously referred to, causes the top
of the head to be at a more marked angle with the forehead than in men (Ecker). This
characteristic was recognized by the Greek sculptors (Havelock Ellis). The cephalic index,
which shows the relation of skull breadth to skull length, is of doubtful value in determin-
ing sex.
The Fontanelles (Fonticuli).
Before birth the bones at the vertex and side of the skull are sep'arated from each other by
membranous intervals in which bone is deficient. These intervals are principally found at the
four angles of the parietal bones. Hence there are six fontanelles. Their formation is due to
the wave of ossification being circular and the bones quadrilateral ; the ossific matter first meets
at the margins of the bones, at the points nearest to their centres of ossification, and vacuities
1 J. Bland Sutton in Henry Morris' Human Anatomy. 2 Ibid.
3 Man and Woman, by Havelock Ellis.
SUPERNUMERARY,. WORMIAN OR SUTURAL BONES
103
or spaces are left at the angles, which are called fontanelles, so named from the pulsations of the
brain, which are perceptible at the anterior fontanelle, and have been likened to the rising of water
in a fountain. The anterior or bregmatic fontanelle (fonticulusfrontalis} (Fig. 62), is the largest ;
it is lozenge-shaped, and corresponds to the junction of the sagittal and coronal sutures ; the poste-
rior fontanelle (fonticulus occipitali.?) (Fig- 62), of smaller size, is triangular, and is situated at the
junction of the sagittal and lambdoid sutures ; the remaining ones, the antero-lateral and the pos-
tero-lateral fontanelles (fonticulus sphenoidalis etfoniiculus Ihastoidens} (Fig. 63) , are situated at
the inferior angles of each parietal bone. The antero-lateral fontanelle is closed in from one to two
months after birth; the postero-lateral is not completely closed until the end of the first year. The
posterior fontanelle is closed in one or two months after birth ; the anterior fontanelle remains open
until the middle of the first or the beginning of the second year. Sometimes the anterior fontanelle
remains open beyond two years, and is occasionally persistent throughout life. Each space is grad-
ually filled in by an extension of the ossifying process or by the development of a Wormian bone.
Supernumerary, Wormian,1 Sutural or Epactal Bones (Ossa Triquetra).
In addition to the constant centres of ossification of the skull, additional ones are occasion-
ally found in the course of the sutures. These form irregular, isolated bones, interposed between
the cranial bones, and have been termed Wormian bones or Ossa triquetra. They are most
FIG. 62. — Skull at birth, showing the anterior and
posterior fontanelles.
FIG. 63.— The lateral fontanelles.
frequently found in the course of the lambdoid suture, but occasionally also occupy the situation
of the fontanelles, especially the posterior and, more rarely, the anterior. Frequently one is
found between the anterior inferior angle of the parietal bone and the greater wing of the
FIG. 64. — Wormian bones.
FIG. 65.
FIG. 66.
sphenoid, the epicteric bone or the pterion ossicle (Fig. 63). They have a great tendency to be
symmetrical on the two sides of the skull, and they vary much in size, being in some cases not
larger than a pin's head, and confined to the outer table; in other cases so large that one pair of
these bones may form the whole of the occipital bone above the superior curved lines, as described
1 Wormius, a physician of Copenhagen, is said to have given the first detailed description of these bones.
104
THE SKELETON
by Beclard and Ward. Their number is generally limited to two or three, but more than a
hundred have been found in the skull of an adult hydrocephalic skeleton. In their development,
structure, and mode of articulation they resemble the other cranial bones.
Congenital Fissures and Gaps.
An arrest in the ossifying process may give rise to deficiencies or gaps; or to fissures, which
are of importance in a medico-legal point of view, as they are liable to be mistaken for fractures.
The fissures generally extend from the margins toward the centre of the bone, but the gaps
may be found in the middle as well as at the edges. In course of time they may become covered
with a thin lamina of bone.
BONES OF THE FACE (OSSA FACIEI .
The Facial Bones are fourteen in number — viz., the
Two Nasal. Two Palate.
Two Superior Maxillae. Two Inferior Turbinated.
Two Lachrymal. Vomer.
Two Malar. Inferior Maxilla or Mandible.
, " Of these, the upper and lower jaws are the fundamental bones for mastication,
and the others are accessories; for the chief function of the facial bones is to
provide an apparatus for mastication, while subsidiary functions are to provide for
the sense organs (eye, nose, tongue) and a vestibule to the respiratory and vocal
organs. Hence the variations in the shape of the face in man and the lower
animals depend chiefly on the question of the character of their food and their
mode of obtaining it."1
The Nasal Bones (Ossa Nasalia).
The nasal (nasus, the nose) are two small oblong bones, varying in size and
form in different individuals; they are placed side by side at the middle and upper
Nasal bone.
Nasal proc.
Infra-orbital
foramen.
Ant. nasal spine.
Lachrymal bone.
Orbital surface.
Infra-orbital
groove.
Artie, with malar.
Post, dental
canals.
Maxillary
tuberosity.
FIG. 67. — Nasal and lachrymal bones in situ.
part of the face, forming, by their junction, "the bridge" of the nose (Fig. 67).
Each bone presents for examination two surfaces and four borders.
1 W. W. Keen, American edition, 1887, p. 185.
THE SUPERIOR MAXILLARY BOXES
105
Surfaces. Outer Surface. — The outer surface is concave from above downward,
convex from side to side; it is covered by the Pyramidalis and Compressor nasi
muscles, and gives attachment at its upper part to a few fibres of the Occipito-
frontalis muscle (Theile). It is marked by numerous small arterial furrows, and
perforated about its centre by a foramen (foramen nasale), sometimes double,
for the transmission of a small vein.
Inner Surface. — The inner surface is concave from side to side, convex from
above downward; in which direction it is traversed by a longitudinal groove
(sometimes a canal), for the
With frontal bone.
With
With
'opposite bone.
Outer Surface.
FIG. 68. — Right nasal bone.
frontal spine.
Crest.
With
perpendicular
plate of
ethmoid.
Groove for nasal nerve.
Inner Surface.
FIG. 69. — Left nasal bone.
passage of a branch of the nasal
nerve.
Borders. Superior Border.—
The superior border is narrow,
thick, and serrated, for articula-
tion with the nasal notch of the
frontal bone.
Inferior Border. — The inferior
border is broad, thin, sharp, in-
clined obliquely downward, out-
ward, and backward, and serves
for the attachment of the lateral
cartilage of the nose. This bor-
der presents, about its middle, a notch, through which passes the branch of the
nasal nerve above referred to, and is prolonged at its inner extremity into a sharp
spine, which, when articulated with the opposite bone, forms the nasal angle.
External Border. — The external border is serrated, bevelled at the expense of
the internal surface above and of the external below, to articulate with the nasal
process of the superior maxillary.
Internal Border. — The internal border, thicker above than below, articulates
with its fellow of the opposite side, and is prolonged behind into a vertical crest,
which forms part of the septum of the nose; this crest articulates above down-
ward with the nasal spine of the frontal above, and the perpendicular plate of
the ethmoid, and the triangular septal cartilage of the nose.
Development. — By one centre for each bone, which appears about the eighth week.
Articulations. — With four bones: two of the cranium, the frontal and ethmoid,
and two of the face, the opposite nasal arid the superior maxillary.
Attachment of Muscles. — A few fibres of the Occipito-frontalis muscle.
The Superior Maxillary Bones (Upper Jaw Bones or Maxillae).
The superior maxillae (maxilla, the jaw bone) are the most important bones
of the face from a surgical point of view, on account of the number of diseases to
which some of their parts are liable. Their careful examination becomes, there-
fore, a matter of considerable interest. They are the largest bones of the face,
excepting the lower jaw, and form, by their union, the whole of the upper jaw.
Each maxilla assists in the formation of three cavities, the roof of the mouth, the
floor and outer wall of the nasal fossae, and the floor of the orbit, and also enters
into the formation of two fossae, the zygomatic and spheno-maxillary, and two
fissures, the spheno-maxillary and pterygo-m axillary. The bone presents for exam-
ination a body and four processes — malar, nasal, alveolar, and palate.
The Body of the Superior Maxilla (Corpus Maxillae).
The body is somewhat cuboid and is hollowed out in its interior to form a
large cavity, the antnun of Highmore (sinus maxillaris). Its surfaces are four —
100
THE SKELETON
an external or facial, a posterior or zygoraatic, a superior or orbital, and an
internal or nasal.
Surfaces. External Surface (fades anterior}. — The external anterior or facial
surface (Fig. 70) is directed forward and outward. It presents at its lower part a
series of eminences corresponding to the position of the anterior five alveoli (juga
alveolaria) . Just above those for the incisor teeth is a depression, the incisive or
myrtiform fossa, which gives origin to the Depressor ahe nasijand below it to the
alveolar border is attached a slip of the Orbicularis oris. Above and a little exter-
nal to it the Compressor nasi arises. More external is another depression, the
canine fossa (fossa canina), larger and deeper than the incisive fossa, from which it
is separated by a vertical ridge, the canine eminence, corresponding to the socket of
the canine tooth. The canine fossa gives origin to the Levator anguli oris. Above
the canine fossa is the infraorbital foramen (foramen infraorbitale) , the termination
Outer Surface.
TENDO OCUL
Incisive fossa.
Posterior dental
canals.
Maxillary tuberosity.
FIG. 70. — Left superior maxilla. Outer surface.
of the infraorbital canal ; it transmits the infraorbital vessels and nerve. Some-
times the infraorbital canal opens by two, very rarely by three, orifices on the
face. Above the infraorbital foramen is the margin of the orbit (margo infraor-
bitalis), which affords partial attachment to the Levator labii superioris proprius.
To the sharp margin of bone which bounds this surface in front and separates
it from the internal surface is attached the Dilator naris posterior.
Posterior Surface (fades infratemporalis) . — The posterior or zygomatic or infra-
temporal surface is convex, directed backward and outward, and forms part of the
zygomatic fossa. It is separated from the facial surface by a strong ridge of bone,
the malar process, which extends upward from the socket of the second molar
tooth. It presents about its centre several apertures leading to canals in the
substance of the bone; they are termed the posterior dental canals (foramina alveo-
laria), and transmit the posterior dental vessels and nerves. At the lower part of
this surface is a rounded eminence, the maxillary tuberosity (tuber maxillare),
especially prominent after the growth of the wisdom-tooth, rough on its inner
THE SUPERIOR MAXILLARY BONES 107
side for articulation with the tuberosity of the palate bone, and sometimes with
the external pterygoid plate. It gives attachment to a few fibres of origin of
the Internal pterygoid muscle. Immediately above this is a smooth surface,
which forms the anterior boundary of the spheno-maxillary fossa; it presents a
groove which, running obliquely downward, is converted into a canal by articu-
lation with the palate bone, forming the posterior palatine or palato-maxillary canal
for the descending palatine artery and great palatine nerve.
Superior Surface (fades orbitalis). — The superior or orbital surface is thin,
smooth, triangular, and forms part of the floor of the orbit. It is bounded in-
ternally by an irregular margin which in front presents a notch, the lachrymal notch
(incisura lacrimalis), which receives the lachrymal bone; in the middle articulates
with the os planum of the ethmoid, and behind with the orbital process of the
palate bone; bounded externally by a smooth, rounded edge which enters into the
formation of the spheno-maxillary fissure, and which sometimes articulates at its
anterior extremity with the orbital plate of the sphenoid; bounded in front by part
of the circumference of the orbit, which is continuous on the inner side with the
nasal, on the outer side with the malar process. Along the middle line of the orbital
surface is a deep groove, the infraorbital groove (sulcus infraorbitalis) , for the pas-
sage of the infraorbital vessels and nerve. The groove commences at the middle
of the outer border of this surface, and, passing forward, terminates in a canal,
which subdivides into two branches. One of the canals, the infraorbital canal
(canalis infraorbitalis}, opens just below the margin of the orbit; the other, which
is smaller, runs downward in the substance of the anterior wall of the antrum;
it is called the anterior dental canal, and transmits the anterior dental vessels
and nerve to the front teeth of the upper jaw. From the back part of the
infraorbital canal a second small canal is sometimes given off, which runs down-
ward in the outer wall of the antrum, and conveys the middle dental nerve to
the bicuspid teeth. Occasionally this canal is derived from the anterior dental.
At the inner and fore part of the orbital surface, just external to the lachrymal
groove for the nasal duct, is a depression which gives origin to the Inferior oblique
muscle of the eye.
Internal Surface. — The internal surface (Figs. 71 and 81) is unequally divided
into two parts by a horizontal projection of bone, the palate process (processus
palatinus) : the portion above the palate process is known as the nasal surface (fades
namlis}. It forms part of the outer wall of the nasal fossa. Below the palate
process is the cavity of the mouth. The superior division of the nasal surface
presents a large, irregular opening, the maxillary hiatus (hiatus maxillaris), leading
into the antrum of Highmore. At the upper border of this aperture are numerous
broken cellular cavities, which in the articulated skull are closed in by the ethmoid
and lachrymal bones. Below the aperture is a smooth concavity which forms part
of the inferior meatus of the nasal fossae, and behind it is a rough surface which
articulates with the perpendicular plate of the palate bone, traversed by a groove
which, commencing near the middle of the posterior border, runs obliquely down-
ward and forward, and forms, when completed by its articulation with the palate
bone, the posterior palatine or palato-maxillary canal. In front of the opening of the
antrum is a deep groove, converted into a canal (canalis nasolacrimalis) by the
lachrymal and inferior turbinated bones. The groove is called the lachrymal groove
(sulcus lacrimalis), and lodges the nasal duct. More anteriorly is a well-marked
rough ridge, the inferior turbinated crest (crista conchalis), for articulation with the
inferior turbinated bone. The shallow concavity above this ridge forms part of the
middle rneatus of the nose, while that below it forms part of the inferior meatus.
The portion of this surface below the palate process is concave, rough, and uneven,
and perforated by numerous small foramina for the passage of nutrient vessels.
It enters into the formation of the roof of the mouth.
108
THE SKELETON
The Antrum of Highmore, Maxillary Antrum, or Maxillary Sinus (sinus maxil-
laris), is a pyramidal cavity hollowed out of the body of the maxillary bone.
It varies much in size. It is in most cases a large cavity, but in some is very
small. The apex of the antrum, directed outward, is formed by the malar process;
Bones partially dosing orifice of antrum
marked in outline.
Ethmoid.
Inferior turbinated.
Palate.
Anterior nasal spine.
Bristle passed
through anterior
palatine canal.
FIG. 71. — Left superior maxilla. Internal surface.
its base by the outer wall of the nose. Its walls are everywhere exceedingly thin,
and correspond to the orbital, facial, and zygomatic surfaces of the body of the
bone. The antral floor is, in most persons, on a level with the floor of the nasal
fossa, but in some individuals it is on a lower level. Not unusually the inner
wall of the antrum will be found to contain depressions or pockets. In rare
instances an antral cavity is made into two by a bony septum. Its inner wall or
base presents, in the disarticulated bone, a large, irregular aperture (hiatus
maxillaris), which communicates with the nasal fossa. The margins of this
aperture are thin and ragged, and the aperture itself is much contracted by its
articulation with the ethmoid above, the inferior turbinated below, and the
palate bone behind.1 In the articulated skull this cavity communicates with
the middle meatus of the nasal cavity, generally by two small apertures left
between the above-mentionsd bones. In the recent state usually only one small
opening exists, near the upper part of the cavity, sufficiently large to admit the
end of a probe, the other being closed by the lining membrane of the sinus. That
the opening into the nasal fossa does not afford the best drainage is demon-
strated, when we note that it is at the highest and not at the lowest point of the
antrum. "In rare instances the antrum communicates with the anterior eth-
moidal cells, or the orbital and posterior ethmoidal cells and sphenoidal sinuses."2
At birth the antrum exists, though in a rudimentary state. It attains its full
size from the twelfth to the fourteenth year.
Crossing the cavity of the antrum are often seen several projecting laminae of
bone, similar to those seen in the sinuses of the cranium; and on its posterior wall
1 In some cases, at any rate, the lachrymal bone encroaches slightly on the anterior superior portion of the
opening, and assists in forming the inner wall of the antrum. — ED. of 15th English Edition.
2 D. Kerfoot Shute, in the Reference Handbook of the Medical Sciences.
THE SUPERIOR MAXILLARY BONES 109
arc the posterior dental canals, transmitting the posterior dental vessels and nerves
to the teeth. Projecting into the floor are several conical processes, corresponding
to the roots of the first and second molar teeth;1 in some cases the floor is per-
forated by the teeth in this situation.
It is from the extreme thinness of the walls of this cavity that we are enabled to explain how
a tumor growing from the antrum encroaches upon the adjacent parts, pushing up the floor of
the orbit, and displacing the eyeball, projecting inward into the nose, protruding forward on
to the cheek, and making its way backward into the zygomatic fossa and downward into the
mouth.
The Processes of the Superior Maxillae.
Malar Process (processus zygomaticus). — The malar process is a rough, trian-
gular eminence, situated at the angle of separation of the facial from the zygo-
matic surface. In front it is concave, forming part of the facial surface; behind
it is also concave, and forms part of the zygomatic fossa; above it is rough and
serrated for articulation with the riialar bone; whilst below a prominent ridge
marks the division between the facial and zygomatic surfaces. A small part of
the Masseter muscle arises from this process.
Nasal Process (processus frontalis). — The nasal process is a strong, triangular
plate of bone, which projects upward, inward, and backward by the side of the
nose, forming part of its lateral boundary. Its external surface is concave, smooth,
perforated by numerous foramina, and gives attachment to the Levator labii
superioris alseque nasi, the Orbicularis palpebrarum, and Tendo oculi. Its
internal surface forms part of the outer wall of the nasal fossae; at its upper
part it presents a rough, uneven surface, which articulates with the ethmoid
bone, closing in the anterior ethmoidal cells; below this is a transverse ridge, the
superior turbinated crest (crista ethmoidalis), for articulation with the middle tur-
binated bone of the ethmoid, bounded below by' a shallow, smooth concavity
which forms part of the middle meatus; below this again is the inferior turbinated
crest (already described), where the process joins the body of the bone. Its upper
border articulates with the frontal bone. The anterior border of the nasal process
is thin, directed obliquely downward and forward, and presents a serrated edge for
articulation with the nasal bone; its posterior border is thick, and hollowed into
a groove, the lachrymal groove (sulcus lacrimalis) , for the naso-lachrymal duct: of
the two margins of this groove, the inner one articulates with the lachrymal bone;
the outer one forms part of the circumference of the orbit. Just where the latter
joins the orbital surface is a small tubercle, the lachrymal tubercle ; this serves as
a guide to the position of the lachrymal sac in the operation for fistula lachrymalis.
The lachrymal groove in the articulated skull is converted into a canal (canalis
lacrimalis) by the lachrymal, bone and lachrymal process of the inferior turbin-
ated; it is directed downward, and a little backward and outward, is about the
diameter of a goose-quill, slightly narrower in the middle than at either extremity,
and terminates below in the inferior meatus. It lodges the nasal duct.
Alveolar Process (processus alveolaris). — The alveolar process is the thickest
and most spongy part of the bone, broader behind than in front, and excavated
into deep cavities for the reception of the teeth (alveoli dentales). These cavities
are eight in number, and vary in size and depth according to the teeth they con-
tain. That for the canine tooth is the deepest; those for the molars are the
widest, and subdivided into minor cavities by septa; those for the incisors are
single, but deep and narrow. The limbus alveolaris is the broad inferior margin
of the alveolar process. On the anterior surface are five projections correspond-
1 The number of teeth whose fangs are in relation to the floor of the antrum is variable. The antrum ' 'may
extend so as to be in relation to all the teeth of the true maxilla, from the canine to the dens sapienlice.'' (See Mr.
Salter on Abscess of the Antrum, in a System of Surgery, edited by T. Holmes, 2d ed., vol. iv. p. 356.) — ED. of
15th English Edition.
110
THE SKELETON
Foramen of Stenson.
Palate process of
maxillary bone
ior palatine canal.
ing to the five anterior alveoli. They are called juga alveolaria. The cavities
for the teeth are separated by septa inter alveolaria. The Buccinator muscle arises
from the outer surface of this process as far forward as the first molar tooth.
Palate Process (processus palatinus}. — The palate process, thick and strong,
projects horizontally inward from the inner surface of the bone. It is much thicker
in front than behind, and
Ant nor palatine canal. forms a considerable part
of the floor of the nostril
and the roof of the mouth.
^Foramen of Scarpa. Its inferior surface (Fig.
72) is concave, rough and
uneven, contains numer-
ous little cavities for the
glands of the mucous
membrane, and forms
part of the roof of the
mouth. This surface is
perforated by numerous
foramina for the passage
of the nutrient vessels,
channelled at the back
part of its alveolar bor-
der by a longitudinal
Horizontal plate' \ Xv" / / groo ve, sometimes a canal,
of palate bone. \ \J/ / for the transmission of
the posterior palatine
vessels, and the great pos-
terior palatine nerve from
Meckel's ganglion, and
presents little depressions
for the lodgement of the palatine glands. When the two superior maxillte
bones are articulated together, a large orifice may be seen in the middle
line, immediately behind the incisor teeth. This is the anterior palatine fossa
(foramen incisivum}. On examining the bottom of this fossa four canals are
seen : two branch off laterally to the right and left nasal fossfe, and two, one in
front and one behind, lie in the middle line. The former pair of these openings
are named the incisor foramina or foramina of Stenson ; they are the openings of
the forking incisor canal (canalis incisivus), through which pass the anterior or
terminal branches of the descending or posterior palatine arteries, which ascend
from the mouth to the nasal fossae, and they contain the remains of Jacobson's
organ. The canals in the middle line are termed the foramina of Scarpa, and
transmit the naso-palatine nerves, the left passing through the anterior, and the
right through the posterior, canal. Occasionally in adults' skulls, often in chil-
dren's skulls, on the palatal surface of the process a delicate linear suture may
sometimes be seen extending from the anterior palatine fossa to the interval
between the lateral incisor and the canine tooth. This marks out the inter-
maxillary or pre-maxillary bones or the incisive bone (os incisivum) on each side.
It is the portion of the upper jaw which is in front of the anterior palatine
foramen, and which in some animals exists permanently as a separate piece.
It includes the whole thickness of the alveolus, the corresponding part of the floor
of the nose, and the anterior nasal spine, and contains the sockets of the incisor
teeth. The pre-maxillary bone has a separate centre of ossification and develops
in association with the vertical plate of the ethmoid and the vomer. The incisive
bones, which are always present in the fretus, usually join the rest of the bone
Accessory palatine foramen.
FIG. 72. — The palate and alveolar arch.
THE SUPERIOR MAXILLARY BONES
111
ENDO-GNATHION
ENDO-GNATHION
MCSO-GNATHION
EXO-GNATHION
ENDO-MESO-GNATHION
SUTURE
ENDO-EXO-GNATHION
SUTURE
MESO- EXO-GNATHION
SUTURE
early in development, more or less well-marked sutures (sutura incisiva) indi-
cating the lines of union. In double hare-lip the incisive bones covered by the
median part of the lip are frequently not joined to the palate processes of the
superior maxillary bones, but are fixed to the nasal septum. Albrecht maintains
that instead of two intermaxillary seg-
ments or incisive bones, each carrying
two incisor teeth, there are originally
four, each carrying the rudiment of
one tooth and each of a triangular
shape, the apices approaching at the
anterior palatine canal. The seg-
ments are separated by five sutures.
The maxilla is called the exo-gnathion,
each mesial segment is called an endo-
gnathion, and each lateral segment
a, meso-gnathion. In hare-lip the cleft
may be purely in the soft parts, but may pass into the nostril, the alveolar portion
of the maxilla, or through the palate bone (cleft palate). In hare-lip with cleft
palate (alveolar hare-lip) Kolliker believes that the cleft is between the maxilla and
the intermaxillary bone; that is, between the exo-gnathion and the meso-gnathion.
Albrecht is of the opinion that the cleft is between the endo-gnathion and the meso-
gnathion. In some cases of double hare-lip the pre-maxillary segment contains the
germs of four incisors, and in such a case the cleft must be between the exo-
gnathion and the meso-gnathion. In other cases it contains but two, and in such
a case the cleft must be as indicated by Albrecht, as Fergusson's explanation is
not in accordance with our knowledge of development. Fergusson believed that
if the germs of four incisors are not present the missing ones were lost in the gap.
The upper surface of the palate process is concave from side to side, smooth, and
forms part of the floor of the nose. It presents the upper orifices of the foramina of
FIG. 73. — The pre-maxilla and its sutures. (Albrecht.)
FIG. 74. — Kolliker's theory of alveolar hare-lip.
(Poirier and Charpy.)
FIG. 75. — Alveolar hare-lip according to the theory of
Albrecht. (Poirier and Charpy.)
Stenson and Scarpa, the former being on each side of the middle fine, the latter
being situated in the intermaxillary suture, and therefore not visible unless the two
bones are placed in apposition. The outer border of the palate process is incorpor-
ated with the rest of the bone. The inner border is thicker in front than behind, and
is raised above into a ridge, the nasal crest (crista nasalis), which, with the corre-
sponding ridge in the opposite bone, forms a groove for the reception of the vomer.
In front this crest rises to a considerable height, and this portion is named the incisor
crest. The anterior margin is bounded by the thin, concave border of the opening
of the nose, prolonged forward internally into a sharp process, forming, with a
similar process of the opposite bone, the anterior nasal spine (spina nasalis anterior}.
The posterior border is serrated for articulation with the horizontal plate of the
palate bone.
112
THE SKELETON
Anterior Surface.
Inferior Surface.
Development. — This bone commences to ossify at a very early period, and
ossification proceeds in it with great rapidity, so that it is difficult to ascertain with
certainty its precise number of centres. It appears, however, probable that it is
ossified from four centres, which are deposited in membrane. 1. One which forms
that portion of the body of the bone which lies internal
to the infraorbital canal, including the floor of the orbit,
the outer wall of the nasal fossa, and the nasal process.
2. A second which gives origin to that portion of the
bone which lies external to the infraorbital canal and the
malar process. 3. A third from which is developed the
palatine process posterior to Stenson's canal and the ad-
joining part of the nasal wall. 4. And a fourth for the
front part of the alveolus which carries the incisor teeth
and corresponds to the pre-maxillary bone of the lower
animals. These centres appear about the eighth week,
and by the tenth week the three first-named centres
have become fused together and the bone consists of two
portions, one the maxilla proper, and the other the pre-
maxillary portion. The suture between these two por-
tions on the palate persists till middle life, but is not to
be seen on the facial surface. This is believed by Cal-
lender to be due to the fact that the front wall of the
sockets of the incisive teeth is not formed by the pre-
FIG. 76. — Development of maxillary bone, but by an outgrowth from the facial part
•superior maxillary bone. At . , * . ...» „,
birth. ot the superior maxilla. 1 he antrum appears as a shal-
low groove on the inner surface of the bone at an earher
period than any of the other nasal sinuses, its development commencing about
the fourth month of foatal life. The sockets for the teeth are formed by the
growing downward of two plates from the dental groove, which subsequently
becomes divided by partitions jutting across from the one to the other. If the
two palate processes fail to unite partially or completely, a partial or complete
cleft palate results.
Articulations. — With nine bones : two of the cranium, the frontal and ethmoid,
and seven of the face — viz., the nasal, malar, lachrymal, inferior jturbinated, palate,
vomer, and its fellow of the opposite side. Sometimes it articulates with the orbital
plate of the sphenoid, and sometimes with its external pterygoid plate.
Attachment of Muscles. — To twelve: the Orbicularis palpebrarum, Obliquus
oculi inferior, Levator labii superioris alaeque nasi, Levator labii superioris pro-
prius, Levator anguli oris, Compressor nasi, Depressor ahe nasi, Dilatator naris
posterior, Masseter, Buccinator, Internal pterygoid, and Orbicularis oris.
CHANGES PRODUCED IN THE UPPER JAW BY AGE.
At birth and during infancy the diameter of the bone is greater in an antero-posterior than
in a vertical direction. Its nasal process is long, its orbital surface large, and its tuberosity
well marked. In the adult the vertical diameter is the greater, owing to the development of
the alveolar process and the increase in size of the antrum. In old age the bone approaches
again in character to the infantile condition: its height is diminished, and after the loss of the
teeth the alveolar process is absorbed, and the lower part of the bone contracted and diminished
in thickness.
The Lachrymal Bone (Os Lacrimale).
The lachrymal (lachryma, a tear) is the smallest and most fragile bone of
the face. There are two lachrymal bones. They are situated at the front part
of the inner wall of the orbit (Fig. 67), and resemble somewhat in form, thinness,
THE MALAR BONE 113
and size a finger-nail; hence they are termed theossa unguis. Each bone presents
for examination two surfaces and four borders.
Surfaces. External Surface. — The external or orbital surface (Fig. 77) is divided
by a vertical ridge, the lachrymal crest (crista lacrimalis posterior}, into two parts.
The portion of bone in front of this ridge, the lachrymal sulcus (sulcus lacrimalis},
presents a smooth, concave, longitudinal groove, the free margin of which unites
with the nasal process of the superior maxillary bone, completing the lachrymal
groove. The upper part of this groove (fossa sacci lacrimalis}
lodges the lachrymal sac; the lower part (sulcus lacrimalis)
lodges the nasal duct. The portion of bone behind the ridge
is smooth, slightly concave, and forms part of the inner wall
of the orbit. The ridge, with a part of the orbital surface
immediately behind it, affords attachment to the Tensor tarsi
muscle: it terminates below in a small, hook-like projection,
the hamular process (hamulus lacrimalis), which articulates
with the lachrymal tubercle of the superior maxillary bone,
and completes the upper orifice of the lachrymal groove.
It sometimes exists as a separate piece, which is then called
the lesser lachrymal bone.
Internal Surface. — The internal or nasal surface presents
I ip !• il * 1 • j Illitl UOiie. J\Alfc!I Ilcll »ur-
a depressed furrow, corresponding to the ridge on its outer face. (Slightly enlarged.)
surface. The surface of bone in front of this forms part of
the middle meatus, and that behind it articulates with the ethmoid bone, fill-
ing in the anterior ethmoidal cells.
Borders. — Of the four borders, the anterior is the longest, and articulates with
the nasal process of the superior maxillary bone. The posterior, thin and uneven,
articulates with the os planum of the ethmoid. The superior, the shortest and
thickest, articulates with the internal angular process of the frontal bone. The
inferior is divided by the lower edge of the vertical crest into two parts; the poste-
rior part articulates with the orbital plate of the superior maxillary bone; the
anterior portion is prolonged downward into a pointed process, which articulates
with the lachrymal process of the inferior turbinated bone and assists in the forma-
tion of the lachrymal groove.
Development. — By a single centre, which makes its appearance soon after ossifi-
cation of the vertebne has commenced.
Articulations. — With four bones : two of the cranium, the frontal and ethmoid,
and two of the face, the superior maxillary and the inferior turbinated.
Attachment of Muscles. — To one muscle, the Tensor tarsi.
The Malar Bone (Os Zygomaticum).
The name malar is derived from mala, the cheek. The malar or yoke bone is
also called the cheek bone. There are two malar bones. Each is a small, quad-
rangular bone, situated at the upper and outer part of the face. They form
the prominence of the cheek, part of the outer wall and floor of the orbit, and
part of the temporal and zygomatic fossae (Fig. 78). Each bone presents for
examination an external and an internal surface; four processes, the frontal,
orbital, maxillary, and zygomatic processes; and four borders.
Surfaces. External or Malar Surface (fades malaris). — The external surface
(Fig. 79) is smooth, convex, perforated near its centre by a small aperture, the
malar foramen (foramen zygomaticofaciale), for the passage of nerves and vessels
from the orbit. The malar surface is covered by the Orbicularis palpebrarum
muscle, and affords attachment to the Zygomaticus major and minor muscles.
8
114
THE SKELETON
Internal or Temporal Surface (fades temporalis) . — The internal surface (Fig. 80),
directed backward and inward, is concave, presenting internally a rough,
triangular surface, for articulation with the superior maxillary bone; and exter-
nally, a smooth concave surface, which above forms the anterior boundary of
Frontal process Ext. angular process
Zygoma-
tic proc.
FIG. 78. — Right malar bone in situ.
the temporal fossa, and below, where it is wider, forms part of the zygomatic
fossa. This surface presents, a little above its centre, the aperture of a malar
canal (foramen zygomaticotemporale) , and affords attachment to a portion of the
Masseter muscle at its lower part.
With frontal.
FIG. 79. — Left malar bone. Outer surface.
FIG. 80. — Left malar bone. Inner surface.
Processes. Frontal Process (processus frontosphenoidalis). — Of the four
processes, the frontal is thick and serrated, and articulates with the external
angular process of the frontal bone. To its orbital margin is attached the
external tarsal ligament.
Orbital Process. — The orbital process is a thick and strong plate, which projects
backward from the Orbital margin of the bone. Its supero-internal surface (fades
THE PALATE BONE 115
orbilalis), smooth and concave, forms, by its junction with the orbital surface of the
superior maxillary bone and with the great wing of the sphenoid, part of the floor
and outer wall of the orbit. Its infero-external surface, smooth and convex, forms part
of the zygomatic and temporal fossse. Its anterior margin is smooth and rounded,
forming part of the circumference of the orbit. Its superior margin, rough and
directed horizontally, articulates with the frontal bone behind the external angular
process. Its posterior margin is rough and serrated for articulation with the
sphenoid; internalli/ it is also serrated for articulation with the orbital surface of
the superior maxillary. At the angle of junction of the sphenoidal and maxillary
portions a short, rounded, non-articular margin is generally seen; this forms the
anterior boundary of the spheno-maxillary fissure: occasionally no such non-
articular margin exists, the fissure being completed by the direct junction of the
maxillary and sphenoid bones or by the interposition of a small Wormian bone in
the angular interval between them. On the upper surface of the orbital process
are seen a single or double temporo -malax foramen (foramen zygomaticoorbitale),
the entrance of the temporo-malar canal. This canal may be bifurcated, or
there may be two canals from the beginning; one of these usually opens on the
posterior surface, the other (occasionally two) on the facial surface: they transmit
filaments (temporo-malar) of the orbital branch of the superior maxillary nerve.
Maxillary Process. — The maxillary process is a rough, triangular surface which
articulates with the malar process of the superior maxillary bone.
Zygomatic Process (processus temporalis). — The zygomatic process, long, narrow,
and serrated, articulates with the zygomatic process of the temporal bone.
Borders. — Of the four borders, the antero-superior or orbital border is smooth,
arched, and forms a considerable part of the circumference of the orbit. The
antero-inferior or maxillary border is rough, and bevelled at the expense of its
inner table, to articulate with the superior maxillary bone; affording attachment
by its margin to the Levator labii superioris proprius, just at its point of junction
with the superior maxillary. The postero-superior or temporal border, curved like
an italic letter /, is continuous above with the commencement of the temporal
ridge; below, with the upper border of the zygomatic arch: it affords attachment
to the temporal fascia. The postero-inferior or zygomatic border is continuous
with the lower border of the zygomatic arch, affording attachment by its rough
edge to the Masseter muscle.
Development. — The malar bone ossifies generally from three centres, which
appear about the eighth week — one for the zygomatic and two for the orbital
portion — and fuse about the fifth month of foetal life. The bone is sometimes,
after birth, seen to be divided by a horizontal suture into an upper and larger
and a lower and smaller division. In some quadrumana the malar bone consists
of two parts, an orbital and a malar, which are ossified by separate centres.
Articulations. — With four bones: three of the cranium, frontal, sphenoid, and
temporal; and one of the face, the superior maxillary.
Attachment of Muscles. — To four: the Levator labii superioris proprius,
Zygomaticus major and minor, and Masseter.
The Palate Bone (Os Palatinum).
The palate bones (palatum, the palate) are situated at the back part of the
nasal fossae: they are wedged in between the superior maxillary bones and the
pterygoid processes of the sphenoid (Fig. 81). Each bone assists in the formation
of three cavities: the floor and outer wall of the nose, the roof of the mouth, and
the floor of the orbit, and enters into the formation of two fossie, the spheno-
maxillary (fossa pterygopalatina) and pterygoid fossae (fossa pterygoidea) ; and one
fissure, the spheno-maxillary fissure (fissura orbitalis inferior). In form the palate
116
THE SKELETON
bone somewhat resembles the letter L, and may be divided into an inferior or
horizontal plate and a superior or vertical plate.
Spheno-palatine for.
Sup. turbinated crest.
Inf. turbinated crest.
Sup. turbinated crest.
Inf. turbinated crest.
'Ant. nasal spine.
FIG. 81. — Internal surface of left maxilla.
The Horizontal Plate of the Palate Bone (Pars Horizontalis) (Figs. 72, 82, 83).
The horizontal plate is of a quadrilateral form, and presents two surfaces and
four borders.
Surfaces. Superior Surface (fades nasalis). — The superior or nasal surface,
concave from side to side, forms the back part of the floor of the nasal cavity.
Inferior Surface (fades palatina). — The inferior or palatine surface, slightly
concave and rough, forms the back part of the hard palate. At its posterior part
may be seen a transverse ridge, more or less marked, for the attachment of part
of the aponeurosis of the Tensor palati muscle. At the outer extremity of this
ridge is a deep groove, the pterygopalatine groove (sulcus pterygopalatinus),
converted into a canal by its articulation with the tuberosity of the superior
maxillary bone, and forming the lower end of the posterior palatine canal (canalis
pterygopalatinus) , the opening of which is called the great palatine foramen (fora-
men palatinummajus). Near this groove the orifices (foramina palatina minora)
of one or two small canals, accessory posterior palatine canals (canales palatini)
may be seen. Through the posterior palatine canal emerge the descending
- palatine artery and the great posterior palatine nerve.
Borders. — The anterior border is serrated, bevelled at the expense of its inferior
surface, and articulates with the palate process of the superior maxillary bone.
The posterior border is concave, free, and serves for the attachment of the soft
palate. Its inner extremity is sharp and pointed, and, when united with the
opposite bone, forms a projecting process, the posterior nasal or palatine spine
(spina nasalis posterior}, for the attachment of the Azygos uvulae muscle. The
external border is united with the lower part of the perpendicular plate almost
at right angles. The internal border, the thickest, is serrated for articulation with
its fellow of the opposite side; its superior edge is raised into a ridge, which, united
with the opposite bone, forms a crest (crista nasalis) into which the vomer is
received.
THE PALATE BONE
117
The Vertical or Perpendicular Plate of the Palate Bone (Pars Perpendicularis).
The vertical or perpendicular plate (Figs. 82 and 83) is thin, of an oblong
form, and directed upward and a little inward. It presents two surfaces, an
external and an internal, and four borders.
Surfaces. Internal, Medial, or Nasal Surface (fades nasalis). — The internal sur-
face presents at its lower part a broad, shallow depression, which forms part of
the inferior meatus of the nose.
Orbital process.
Orbital surface.
Maxillary surface.
Maxillary
process.
Horizontal Plate.
FIG. 82. — Left palate bone. Internal view.
(Enlarged.)
'
I
Immediately above this is a
well-marked horizontal ridge,
the inferior turbinated crest
(crixta conchalis), for articula-
tion with the inferior turbin- Superior m
ated bone ; above this, a Second Spheno-palaKne foramen.—
broad, shallow depression,
which forms part of the mid-
dle meatus, surmounted above
by a horizontal ridge less
prominent than the inferior,
the superior turbinated crest
(crista ethmoidalis) , for articu-
lation with the middle turbin-
ated bone. Above the superior
turbinated crest is a narrow,
horizontal groove, which forms
part of the superior meatus.
External, Lateral, or Maxillary
Surface (fades maxillaris). —
The external surface is rough and irregular throughout the greater part of its extent,
for articulation with the inner surface of the superior maxillary bone, its upper
and back part being smooth where it enters
into the formation of the spheno-maxillary
fossa; it is also smooth in front, where it
covers the orifice of the antrum. Toward
the back part of this surface is a deep groove,
the pterygo-palatine groove, converted into
a canal, the posterior palatine canal (canalis
pterygopalatinus) , by its articulation with
the superior maxillary bone. It transmits
the posterior or descending palatine vessels
and the great or anterior palatine nerve
from Meckel's ganglion.
Borders. Anterior Border (Fig. 82).— The
anterior border is thin, irregular, and pre-
sents opposite the inferior turbinated crest
a pointed, projecting lamina, the maxillary
process (processus maxillaris), which is di-
rected forward, and closes in the lower and
back part of the opening of the antrum.
Posterior Border. — The posterior border
(Fig. 83) presents a deep groove, the edges
of which are serrated for articulation with
the pterygoid process of the sphenoid. At the lower part of this border is seen a
pyramidal process of bone, the pterygoid process or tuberosity of the palate (processus
pyramidalis), which is received into the angular interval between the two pterygoid
Orbital proceso.
.10J, surface.
*
Sphenoidal palatine
foramen.
Sphenoidal process.
Articular portion.
Ron-articular portion.
External Surface.
QOS UVUL/E.J
Horizontal
Plate.
Posterior
nasal spine.
FIG. 83.— Left palate bone.
(Enlarged.)
Posterior view.
118 THE SKELETON
plates of the sphenoid at their inferior extremity. This process presents at its back
part a median groove and two lateral surfaces. The groove is smooth, and forms
part of the pterygoid fossa, affording attachment to the Internal pterygoid muscle ;
whilst the lateral surfaces are rough and uneven, for articulation with the anterior
border of each pterygoid plate. A few fibres of the Superior constrictor arise from
the tuberosity of the palate bone. The base of this process, continuous with the
horizontal portion of the bone, presents the aperture of the accessory descending
palatine canals, through which pass the two smaller descending branches of
Meckel's ganglion ; whilst its outer surface is rough for articulation with the
inner surface of the body of the superior maxillary bone.
Superior Border.— The superior border of the vertical plate presents two well-
marked processes separated by an intervening notch or foramen. The anterior,
or larger, is called the orbital process; the posterior, the sphenoidal process.
Processes. Orbital Process (processus orbitalis). — The orbital process, directed
upward and outward, is placed on a higher level than the sphenoidal. It presents
five surfaces, which enclose a hollow cellular cavity, and is connected with the per-
pendicular plate by a narrow, constricted neck. Of these five surfaces, three are
articular, two non-articular or free surfaces. The three articular are the anterior or
maxillary surface, which is directed forward, outward, and downward, is of an
oblong form, and rough for articulation with the superior maxillary bone. The pos-
terior or sphenoidal surface is directed backward, upward, and inward. It ordinarily
presents a small, open cell, the orbital sinus (sinus orbitalis) , which communicates
with the sphenoidal cells, and the margins of which are serrated for articulation with
the vertical part of the sphenoidal turbinated bone. "The orbital may communicate
not only with the sphenoidal sinus and the ethmoidal cells, but, in rare instances,
with the maxillary antrum."1 The internal or ethmoidal surface is directed inward,
upward, and forward, and articulates with the lateral mass of the ethmoid bone.
In some cases the cellular cavity opens on the internal surface of the bone ; it then
communicates with the posterior ethmoidal cells. More rarely it opens on both
surfaces, and then communicates with both the posterior ethmoidal and the
sphenoidal cells. The non-articular or free surfaces are the superior or orbital
surface, directed upward and outward, of triangular form, concave, smooth, and
forming the back part of the floor of the orbit ; and the external or zygomatic surface,
directed outward, backward, and downward, of an oblong form, smooth, lying in
the spheno-maxillary fossa, and looking into the zygomatic fossa. The latter
surface is separated from the orbital by a smooth, rounded border, which enters
into the formation of the spheno-maxillary fissure.
Sphenoidal Process (processus sphenoidalis) . — The sphenoidal process of the
palate bone is a thin, compressed plate, much smaller than the orbital, and
directed upward and inward. It presents three surfaces and two borders. The
superior surface, the smallest of the three, articulates with the under surface of
the sphenoidal turbinated bone; it presents a groove, which contributes to the
formation of the pterygo-palatine canal. The internal surface is concave, and
forms part of the outer wall of the nasal fossa. The external surface is divided
into an articular and a non-articular portion: the former is rough, for articulation
with the inner surface of the internal pterygoid plate of the sphenoid; the latter is
smooth, and forms part of the spheno-maxillary fossa. The anterior border forms
the posterior boundary of the spheno-palatine notch. The posterior border,
serrated at the expense of the outer table, articulates with the inner surface of
the internal pterygoid plate.
The orbital and sphenoidal processes are separated from one another by a deep
notch, the spheno-palatine notch (incisura sphenopalatinum) , which is converted
1 Dr. D. Kerfoot Shute, in the Reference Handbook of the Medical Sciences.
THE INFERIOR TURBINATED BONE
119
into a foramen, the spheno-palatine foramen (foramen sphenopalatinum) , by articu-
lation with the under surface of the body of the sphenoid bone. Sometimes the
two processes are united above, and form between them a complete foramen (Figs.
82 and 83) , or the notch is crossed by one or more spiculae of bone, so as to form
two or more foramina. In the articulated skull this foramen is seen to pass from
the spheno-maxillary fossa into the back part of the superior meatus. It trans-
mits the spheno-palatine vessels and the superior nasal and naso-palatine nerves.
Development. — From a single centre,' which makes its appearance about the
second month at the angle of junction of the two plates of the bone. From this
point ossification spreads inward to the horizontal plate, downward into the
tuberosity, and upward into the vertical plate. In the foetus the horizontal plate
is much larger than the vertical, and even after it is fully ossified the whole bone
is at first remarkable for its shortness.
Articulations. — With six bones: the sphenoid, ethmoid, superior maxillary,
inferior turbinated, vomer, and opposite palate.
Attachment of Muscles.- -To four: the Tensor palati, Azygos uvulae, Internal
pterygoid, and Superior constrictor of the pharynx.
The Inferior Turbinated Bone ( Concha Nasalis Inferior).
The inferior turbinal or turbinated bones (turbo, a whirl) are situated one on
each side of the outer wall of the nasal fossse. Each inferior turbinated bone
(concha nasalis inferior] consists of a layer of thin, spongy bone, curled upon
NASO-PHARYNGEAL
MEATUS
FTG. 84. — Nasal cavity, right lateral wall, from the left. (Spalteholz.)
itself like a scroll — hence its name " turbinated "— and extends horizontally
along the outer wall of the nasal fossa, immediately below the orifice of the
antrum (Fig. 84). Each bone presents two surfaces, two borders, and two
extremities.
120
THE SKELETON
Surfaces. — The internasal surface (Fig. 85) is convex, perforated by numerous
apertures, and traversed by longitudinal grooves and canals for the lodgement
of arteries and veins. In the recent state it is covered by the lining membrane of
the nose. The external surface is concave (Fig. 86), and forms part of the inferior
meatus.
FIG. 85. — Right inferior turbinated bone. Internal
surface.
FIG. 86.— Right inferior turbinated bone.
External surface.
Borders. — Its upper border is thin, irregular, and connected to various bones
along the outer wall of the nose. It may be divided into three portions : of these,
the anterior articulates with the inferior turbinated crest of the superior maxillary
bone; the posterior with the inferior turbinated crest of the palate bone; the middle
portion of the superior border presents three well-marked processes, which vary
much in their size and form. Of these, the anterior and smallest is situated at
the junction of the anterior fourth with the posterior three-fourths of the bone:
it is small and pointed, and is called the lachrymal process (processus lacrimalis) ;
it articulates by its apex with the anterior inferior angle of the lachrymal bone,
and by its margins with the groove on the back of the nasal process of the supe-
rior maxillary, and thus assists in forming the canal for the nasal duct. At the
junction of the two middle fourths of the bone, but encroaching on its posterior
fourth, a broad, thin plate, the ethmoidal process (processus ethmouLalis) , ascends
to join the unciform process of the ethmoid; from the lower border of this pro-
cess a thin lamina of bone curves downward and outward, hooking over the
lower edge of the orifice of the antrum, which it narrows below: it is called the
maxillary process (processus maxillaris) , and fixes the bone firmly to the outer wall
of the nasal fossa. The inferior border is free and thick, more especially in the
middle of the bone. Bone extremities are more or less narrow and pointed, the
posterior being the more tapering. If the bone is held so that its outer concave
surface is directed backward (i. e., toward the holder), and its superior border, from
which the lachrymal and ethmoidal processes project, upward, the lachrymal pro-
cess will be directed to the side to which the bone belongs.1 In a study of 1000 speci-
mens, Howard A. Lothrop2 did not discover cells in the inferior turbinated bone.
Development. — By a single centre, which makes its appearance about the
middle of fcetal life.
Articulations. — With four bones: one of the cranium, the ethmoid, and three
of the face, the superior maxillary, lachrymal, and palate.
No muscles are attached to this bone.
The Vomer (Ploughshare Bone).
The vomer (vomer, a ploughshare) is a single bone, situated vertically at the
back part of the nasal fossae, forming part of the septum of the nose (Fig. 87).
It is thin, somewhat like a ploughshare in form; but it varies in different indi-
viduals, being frequently bent to one or the other side; it presents for examination
two surfaces and four borders.
1 If the lachrymal process is broken off, as is often the case, the side to which the bone belongs may be known
by recollecting that the maxillary process is nearer the back than the front of the bone. — Ki>. of 15th English
Edition. 2 Annals of Surgery, May, 1903.
THE VOMER
121
Surfaces. — The lateral surfaces are smooth, marked by small furrows for the
lodgement of blood-vessels, and by a groove on each side, sometimes a canal, the
naso-palatine groove or canal, which runs obliquely downward and forward to the
intermaxillary suture; it transmits the naso-palatine nerve.
Space for triangular
cartilage of septum.
Rostrum of sphenoid.
A\x.
FIG. 87. — Vomer in situ.
Borders. — The superior border, the thickest, presents a deep groove, bounded
on each side by a horizontal projecting leaf of bone; these leaves are the alae
(alee vomeris). The groove formed by the alae receives the rostrum of the
sphenoid, while the alae are overlapped and retained by the vaginal processes, which
project from the under surface of the body of the sphenoid at the base of the
pterygoid processes. At the front
of the groove a fissure is left for
the transmission of blood-vessels
to the substance of the bone. The
inferior border, the longest, is
broad and uneven in front, where
it articulates with the two supe-
rior maxillary bones ; thin and
sharp behind, where it joins with
the palate bones. The upper
half of the anterior border usually
consists of two laminae of bone,
in the groove between which is
received the perpendicular plate
of the ethmoid; the lower half,
also separated into two lamella?, receives between them the lower margin of the
septal cartilage of the nose. The posterior border is free, concave, and separates
the nasal fossae behind. It is thick and bifid above, thin below.
The surfaces of the vomer are covered by mucous membrane, which is inti-
mately connected with the periosteum, with the intervention of very little, if any,
With sup. maxill. bones and palate.
FIG. 88. — The vomer.
122
THE SKELETON
submucous connective tissue. Hence polypi are rarely found growing from this
surface, though they frequently grow from the outer wall of the nasal fossae,
where the submucous tissue is abundant.
Development. — The vomer at an early period consists of two laminae, separated
by a very considerable interval, and enclosing between them a plate of cartilage,
the vomerine cartilage, which is prolonged forward to form the remainder of the
septum. Ossification commences in the membrane at the postero-inferior part of
this cartilage by two centres, one on each side of the middle line, which extend
to form the two lamimie. They begin to coalesce at the lower part, but their
union is not complete until after puberty.
Articulations.-- With six bones: two of the cranium, the sphenoid and ethmoid;
and four of the face, the superior maxillary and the two palate bones; and with
the cartilage of the septum.
The vomer has no muscles attached to it.
The Maxillary Bone, Inferior Maxilla, Mandible or Lower Jaw (Mandibula).
The mandible, the largest and strongest bone- of the face, serves for the
reception of the lower teeth. It consists of a curved, horizontal portion, the
body, and two perpendicular portions, the rami, which join the back part of
the body nearly at right angles.
The Horizontal Portion or Body of the Mandible (Corpus Mandibulae).
The horizontal portion or body (Fig. 89) is convex in its general outline, and
curved somewhat like a horseshoe. It presents for examination two surfaces and
two borders.
Coronoid process. Condyle.
Groove for facial artery.
FIG. 89. — The mandible. Outer surface. Side view.
— Angle.
Surfaces. External Surface.— The external surface is convex from side to side,,
concave from above downward. In the median line is a vertical ridge, the symphy-
sis, which extends from the upper to the lower border of the bone, and indicates
the point of junction of the two pieces of which the bone is composed at an early
period of life. The lower part of the ridge terminates in a prominent triangular
eminence, the mental process or protuberance (protuberantia mentalis) . This emi-
nence is rounded below, and often presents a median depression separating two
processes, the mental tubercles (tubera mentalia). It forms the chin, a feature
peculiar to the human skull. On either side of the symphysis, just below the
THE MAXILLARY BONE
123
cavities for the incisor teeth, is a depression, the incisive or incisor fossa, for the
attachment of the Levator menti (or Levator labii inferioris) ; more externally is
attached a portion of the Orbicularis oris (accessorii orbicularis inferioris), and,
still more externally, a foramen, the mental foramen (foramen mentale), for the
passage of the mental vessels and nerve. This foramen is placed just below the
interval between the two bicuspid teeth. Running outward from the base of the
mental process on each side is a ridge, the external oblique line (linea obliqud).
The ridge is at first nearly horizontal, but afterward inclines upward and back-
ward, and is continuous with the anterior border of the ramus: it affords attach-
ment to the Depressor labii inferioris and Depressor anguli oris; below it the
Platysma myoides is attached.
Internal Surface. — The internal surface (Fig. 90) is concave from side to side,
convex from above downward. In the middle line is an indistinct linear depres-
QENIO-HYO-QLOSS
GENIO-HYOIDEUS.
Mylo-hyoid ridge.
Body.
FIG. 90. — The mandible. Inner surface. Side view.
sion, corresponding to the symphysis externally; on either side of this depression,
just below its centre, are four prominent tubercles, placed in pairs, two above and
two below; they are called the genial tubercles or mental spines (spince mentales) , and
afford attachment, the upper pair to the Genio-hyo-glossi, the lower pair to the
Genio-hyoidei, muscles. Sometimes the tubercles on each side are blended into
one; at others they all unite into an irregular eminence; or, again, nothing but an
irregularity may be seen on the surface of the bone at this part. On either side of
the genial tubercles is an dval depression, the sublingual fossa (fovea sublingualis) ,
for lodging the sublingual gland; and beneath the fossa a rough depression on
each side which gives attachment to the anterior belly of the Digastric muscle,
the digastric fossa (fossa digdstrica). At the back part of the sublingual fossa the
internal oblique line or mylo-hyoid ridge (linea mylohyoidea) commences; it is at
first faintly marked, but becomes more distinct as it passes upward and outward,
and is especially prominent opposite the last two molar teeth ; it affords attach-
ment throughout its whole extent to the Mylo-hyoid muscle; the Superior con-
strictor of the pharynx with the pterygo-m axillary ligament being attached above
its posterior extremity, near the alveolar margin. The portion of the bone above
this ridge is smooth and covered by the mucous membrane of the mouth; the
portion below presents an oblong depression, the submaxillary fossa (fovea sub-
maxillaris), wider behind than in front, for the lodgement of the submaxillary
124 THE SKELETON
gland. The external oblique line and the internal or mylo-hyoidean line divide
the body of the bone into a superior or alveolar and an inferior or basilar portion.
Borders. — The superior or alveolar portion of the body (pars alveolaris) has
above a narrow border which is wider and the margins of which are thicker
behind than in front. Its narrow margin is called the limbus alveolaris. It is
hollowed into numerous cavities (alveoli dentales) , for the reception of the teeth ;
these cavities are sixteen in number, and vary in depth and size according to the
teeth which they contain. The cavities are separated from one another by septa
inter alveolar ia. The juga alveolaria are prominences on the outer surface over the
three front alveoli. To the outer side of the alveolar border the Buccinator muscle
is attached upon the buccinator crest (crista buccinatoria) as far forward as the
first molar tooth. The inferior or basilar portion (basis mandibidce) is rounded,
longer than the superior, and thicker in front than behind; it presents a shallow
groove, just where the body joins the ramus, over which tjie facial artery turns.
The Perpendicular Portions or Kami of the Mandible (Kami Mandibolse).
The perpendicular portions or rami are of a quadrilateral form. Each presents
for examination two surfaces, four borders, and two processes.
Surfaces. External Surface. — The external surface is flat, marked with ridges,
and gives attachment throughout nearly the whole of its extent to the Masseter
muscle.
Internal Surface. — The internal surface presents about its centre an oblique
foramen (foramen mandibulare) of the inferior dental canal (canalis mandibulce) , for
the passage of the inferior dental vessels and nerve. The margin of this opening
is irregular; it presents in front a prominent ridge, surmounted by a sharp spine,
the lingula (lingula mandibulae) , which gives attachment to the internal lateral
ligament of the lower jaw, and at its lower and back part a notch leading to
a groove, the mylo-hyoidean groove (sulcus mylohyoideus) , which runs obliquely
downward to the back part of the submaxillary fossa, and lodges the mylo-hyoid
vessels and nerve. Behind the groove is a rough surface, for the insertion of the
Internal pterygoid muscle. The inferior dental canal runs obliquely downward
and forward in the substance of the ramus, and then horizontally forward in the
body ; it is here placed under the alveoli, with which it communicates by small
openings. On arriving at the incisor teeth, it turns back to communicate with
the mental foramen, giving off two small canals, which run forward, to be lost in
the cancellous tissue of the bone beneath the incisor teeth. This canal, in the
posterior two-thirds of the bone, is situated nearer the internal surface of the
jaw; and in the anterior third, nearer its external surface. Its walls are com-
posed of compact tissue at either extremity, and of cancellous in the centre. It
contains the inferior dental vessels and nerve, from which branches are distributed
to the teeth through small apertures at the bases of the. alveoli.
Borders. — The lower border of the ramus is thick, straight, and continuous
with the body of the bone. At its junction with the posterior border is the angle
of the jaw (angulus mandibulce). The outer portion of the angle is called the
gonion. The angle is either inverted or everted, and marked by rough, oblique
ridges on each side, for the attachment of the Masseter externally, and the
Internal pterygoid internally ; the stylo-maxillary ligament is attached to the angle
between these muscles. 'The anterior border is thin above, thicker below, and
continuous with the external oblique line. The posterior border is thick,
smooth, rounded, and covered by the parotid gland. The upper 'border of the
ramus is thin, and presents two processes, separated by a deep concavity, the
sigmoid notch (incisura mandibulce). Of these processes, the anterior is the
coronoid, the posterior the condyloid.
THE MAXILLARY BONE 125
Coronoid Process (processus coronoideus) . — The coronoid process is a thin, flat-
tened, triangular eminence of bone, which varies in shape and size in different
subjects, and serves chiefly for the attachment of the Temporal muscle. Its external
surface is smooth, and affords attachment to the Temporal and Masseter muscles.
Its internal surface gives attachment to the Temporal muscle and presents the
commencement of a longitudinal ridge, which is continued to the posterior part
of the alveolar process. On the outer side of this ridge is a deep groove, con-
tinued below on the outer side of the alveolar process; this ridge and part of the
groove afford attachment, above, to the Temporal; below, to the Buccinator
muscle.
Condyloid Process (processus condyloideus) . — The condyloid process, shorter but
thicker than the coronoid, consists of two portions: the condyle (capitulum man-
dibulce) , and the constricted portion which supports the condyle, the neck (collum
mandibulcB). The condyle is of an oblong form, its long axis being transverse, and
set obliquely on the neck in such a manner that its outer end is a little more
forward and a little higher than its inner. It is convex from before backward
and from side to side, the articular surface extending farther on the posterior
than on the anterior aspect. At its outer extremity is a small tubercle for the
attachment of the external lateral ligament of the temporo-mandibular joint.
The neck of the condyle is flattened from before backward, and strengthened
by ridges which descend from the fore part and sides of the condyle. Its lateral
margins are narrow, the external one giving attachment to part of the external
lateral ligament. Its posterior surface is convex; its anterior is hollowed out on
its inner side by a depression, the pterygoid depression (fovea pterygoidea) , for the
attachment of the External pterygoid muscle.
The Sigmoid Notch (incisura maridibuloe), separating the two processes, is a
deep semilunar depression, crossed by the masseteric vessels and nerve.
Development. — The lower jaw is developed principally from membrane, but
partly from cartilage. The process of ossification commences early — earlier than
in any other bone except the clavicle. The greater part of the bone is formed from
a centre of ossification (dentary), which appears between the fifth and sixth week
in the membrane on the outer surface of Meckel's cartilage. A second centre
(splenial) appears in the membrane on the inner surface of the cartilage, and
from this centre the inner wall of the sockets of the teeth is formed; this termi-
nates above in the lingula. The anterior extremity of Meckel's cartilage becomes
ossified, forming the body of the bone on each side of the syrnphysis. Two supple-
mental patches of cartilage appear at the condyle and at the angle, in each of
which a centre of ossification for these parts appears; the coronoid process is also
ossified from a separate centre. At birth the bone consists of two halves, united
by a fibrous symphysis, in which ossification takes place during the first year.
Articulation. — With the glenoid (mandibular) fossae of the two temporal bones.
Attachment of Muscles. — To fifteen pairs: to its external surface, commencing
at the symphysis, and proceeding backward : Levator menti, Depressor labii infe-
rioris, Depressor anguli oris, Platysma myoides, Buccinator, Masseter; a portion
of the Orbicularis oris (Accessorii orbicularis inferioris) is also attached to this
surface. To its internal surface, commencingat the same point : Genio-hyo-glossus,
Genio-hyoideus, Mylo-hyoideus, Digastric, Superior constrictor, Temporal, Inter-
nal pterygoid, External pterygoid.
CHANGES PRODUCED IN THE LOWER JAW BY AGE.
The changes which the lower jaw undergoes after birth relate (1) to the alterations effected
in the body of the bone by the first and second dentitions, the loss of the teeth in the aged, and
the subsequent absorption of the alveoli; (2) to the size and situation of the dental canal; and
(3) to the angle at which the ramus joins with the body.
126
THE SKELETON
SIDE VIEW OF THE LOWER JAW AT DIFFERENT PERIODS OF LIFE.
At birth (Fig. 91) the bone consists of lateral halves, united by fibrous tissue. The body is
a mere shell of bone, containing the sockets of the two incisor, the canine, and the two tem-
porary molar teeth, imperfectly partitioned from one another. The dental canal is of large size,
and runs near the lower border of the bone, the mental foramen opening beneath the socket of
the first molar. The angle is obtuse (175 degrees), and the condyloid portion nearly in the
same horizontal line with the body; the neck of the condyle is short, and bent backward. The
coronoid process is of comparatively large size, and situated at right angles with the rest of
the bone.
FIG. 91. — Lower jaw bone in newborn. (Spalteholz.)
FIG. 92. — In child six to seven years of age.
(Spalteholz.)
After birth (Fig. 92) the two segments of the bone become joined at the symphysis, from
below upward, in the first year; but a trace of separation may be visible in the beginning of the
second year near the alveolar margin. The body becomes elongated in its whole length, but
more especially behind the mental foramen, to provide space for the three additional teeth
developed in this part. The depth of the body becomes greater, owing to increased growth of
the alveolar part, to afford room for the fangs of the teeth, and by thickening of the subdental
portion, which enables the jaw to withstand the powerful action of the masticatory muscles ; but
the alveolar portion is the deeper of the two, and, consequently, the chief part of the body lies
above the oblique line. The dental canal after the second dentition is situated just above the
level of the mylo-hyoid ridge, and the mental foramen occupies the position usual to it in the
adult. The angle becomes less obtuse, owing to the separation of the jaws by the teeth. (About
the fourth year it is 140 degrees.)
FIG. 93. — In the adult. (Spalteholz.)
In the adult (Fig. 93) the alveolar and basilar portions of the body are usually of equal
depth. The mental foramen opens midway between the upper and lower border of the bone,
THE SUTURES 127
and the dental canal runs nearly parallel with the mylo-hyoid line. The ramus is almost vertical
in direction, and joins the body nearly at right angles.
In old age (Fig. 94) the bone becomes greatly reduced in size; for with the loss of the teeth
the alveolar process is absorbed, and the basilar part of the bone alone remains, consequently,
FIG. 94. — In old age. (Spalteholz.)
the chief part of the bone is below the oblique line. The dental canal, with the mental foramen
opening from it, is close to the alveolar border. The rami are oblique in direction, the angle
obtuse, and the neck of the condyle more or less bent backward.
The Sutures.
The bones of the cranium and face are connected to each other by means of
sutures. That is, the articulating surfaces or edges of the bones are more or less
roughened or uneven, and are closely adapted to each other, a small amount of
intervening fibrous tissue, the sutural ligament, fastening them together. The
cranial sutures may be divided into three sets: 1. Those at the vertex of the
skull. 2. Those at the side of the skull. 3. Those at the base.
The sutures at the vertex of the skull are four: the metopic, the sagittal, the
coronal, and the lambdoid.
The Metopic or Frontal Suture (sutura frontalis) is usually noted in adults as a
trivial fissure, just above the glabella. At birth the two halves of the frontal
bone are separated by the suture. This suture is, as a rule, almost completely
or completely closed during the fifth or sixth year, but occasionally it remains
intact.
The Interparietal or Sagittal Suture (sutura sagittalis) is formed by the junction
of the two parietal bones, and extends from the middle of the frontal bone back-
ward to the superior angle of the occipital. This suture is sometimes perforated,
near its posterior extremity, by the parietal foramen ; and in front, where it joins
the coronal suture, a space is occasionally left which encloses a large Wormian
bone.
The Fronto -parietal or Coronal Suture (sutura coronalis] extends transversely
across the vertex of the skull, and connects the frontal with the parietal bones.
It commences at the extremity of the greater wing of the sphenoid on one side,
and terminates at the same point on the opposite side. The dentations of the
suture are more marked at the sides than at the summit, and are so constructed
that the frontal rests on the parietal above, whilst laterally the frontal supports
the parietal.
128 THE SKELETON
The Occipito-parietal or Lambdoid Suture (sutura lambdoidea), so called from
its resemblance to the Greek letter A, connects the occipital with the parietal
bones. It commences on each side at the mastoid portion of the temporal bone,
and inclines upward to the end of the sagittal suture. The dentations of this
suture are very deep and distinct, and are often interrupted by several small
Wormian bones.
The sutures at the side of the skull extend from the external angular process of
the frontal bone to the lower end of the lambdoid suture behind. The anterior portion
is formed between the lateral part of the frontal bone above and the malar and great
wing of the sphenoid below, forming the fronto-xnalar suture (sutura zygomatico-
frontalis) and fronto-sphenoidal suture (sutura sphenofrontalis) . These sutures
can also be seen in the orbit, and form part of the so-called transverse facial
suture. The posterior portion is formed between the parietal bone above and
the great wing of the sphenoid, the squamous and mastoid portions of the temporal
bone below, forming the spheno-parietal, squamo-parietal, and masto-parietal sutures.
The spheno-parietal (sutura sphenoparietalis) is very short; it is formed by the
tip of the great wing of the sphenoid, which overlaps the anterior inferior angle
of the parietal bone.
The squamo-parietal or squamous suture (sutura squamosa) is arched. It is
formed by the squamous portion of the temporal bone overlapping the middle
division of the lower border of the parietal.
The masto-parietal (sutura parietomastoidea) is a short suture, deeply dentated,
formed by the posterior inferior angle of the parietal and the superior border of
the mastoid portion of the temporal.
The sutures at the base of the skull are the basilar in the centre, and on each
side the petro-occipital, the masto-occipital, the petro-sphenoidal, and the squamo-
sphenoidal.
The Basilar Suture (fissura sphenooccipitalis) is formed by the junction of the
basilar surface of the occipital bone with the posterior surface of the body of
the sphenoid. At an early period of life a thin plate of cartilage exists between
these bones, but in the adult they become fused into one (synchondrosis spheno-
occipitalis) . Between the outer extremity of the basilar suture and the termina-
tion of the lambdoid an irregular suture exists, which is subdivided into two por-
tions. The inner portion, formed by the union of the petrous part of the temporal
with the occipital bone, is termed the petro-occipital fissure (fissura petrooccipitalis) .
The outer portion, formed by the junction of the mastoid part of the temporal
with the occipital, is called the masto-occipital suture (sutura occipitomastoidea) .
Between the bones forming the petro-occipital suture a thin plate of cartilage
exists; in the masto-occipital is occasionally found the opening of the mastoid
foramen. Between the outer extremity of the basilar suture and the spheno-
parietal an irregular suture may be seen, formed by the union of the sphenoid
with the temporal bone. The inner and smaller portion of this suture is termed
the petro-sphenoidal fissure (fissura sphenopetrosa) ; it is formed between the
petrous portion of the temporal and the great wing of the sphenoid; the outer
portion, of greater length and arched, is formed between the squamous portion
of the temporal and the great wing of the sphenoid ; it is called the squamo-
sphenoidal suture (sutura sphenosquamosa) .
The cranial bones are connected with those of the face, and the facial bones
with each other, by numerous sutures, which, though distinctly marked, have
received no special names. The only remaining suture deserving especial con-
sideration is the transverse suture. This extends across the upper part of the face,
and is formed by the junction of the frontal with the facial bones: it extends from
the external angular process of one side to the same point on the opposite side,
and connects the frontal with the malar, the sphenoid, the ethmoid, the lachrymal,
THE VERTEX OF THE SKULL 129
the superior maxillary, and the nasal bones on each side (sutura zygomatico-
jrontalis; the orbital portion of the sutura sphenofrontalis, sutura fronto-
ethmoidalis, sutura frontolacrimalis, sutura frontomaxillaris, sutura nasojrontalis) .
The sutures remain separate for a considerable period after the complete for-
mation of the skull. It is probable that they serve the purpose of permitting the
growth of the bones at their margins, while their peculiar formation, together
with the interposition of the sutural ligament between the bones forming them,
prevents the dispersion of blows or jars received upon the skull. Humphry
remarks, "that, as a general rule, the sutures are first obliterated at the parts in
which the ossification of the skull was last completed — viz., in the neighborhood
of the fontanelles; and the cranial bones seem in this respect to observe a similar
law to that which regulates the union of the epiphyses to the shafts of the long
bones." The same author remarks that the time of their disappearance is ex-
tremely variable: they are sometimes found well marked in skulls edentulous
with age, while in others wrhich have only just reached maturity they can hardly
be traced. The obliteration of the sutures takes place sooner on the inner than
on the outer surface of the skull. The sagittal and coronal sutures are as a rule
the first to become ossified — the process starting near the posterior extremity of
the former and the lower ends of the latter.
THE SKULL AS A WHOLE.
The skull, formed by the union of the several cranial and facial bones already
described, when considered as a whole is divisible into five regions: a superior
region or vertex, an inferior region or base, two lateral regions, and an anterior
region, the face.
The Vertex of the Skull.
The superior region, or vertex, presents two surfaces, an external and an
internal.
Surfaces. External Surface. (This surface as seen from above is called the
norma verticalis.) — The external surface is bounded, in front, by the glabella
and supraorbital ridges; behind, by the occipital protuberance and superior
curved lines of the occipital bone; laterally, by an imaginary line extending from
the outer end of the superior curved line, along the temporal ridge, to the exter-
nal angular process of the frontal bone. This surface includes the greater part of
the vertical portion of the frontal, the greater part of the parietal, and the superior
third of the occipital bone; it is smooth, convex, of an elongated oval form, crossed
transversely by the coronal suture, and from before backward by the sagittal,
which terminates behind in the lambdoid. The point of junction of the coronal
and sagittal sutures is named the bregma, and is represented by a line drawn verti-
cally upward from the external auditory meatus, the head being in its normal posi-
tion. The point of junction of the sagittal and lambdoid sutures is called the
lambda, and is about 2f inches above the external occipital protuberance. From
before backward may be seen the frontal eminences and remains of the suture
connecting the two lateral halves of the frontal bone; on each side of the sagittal
suture are the parietal foramen and parietal eminence, and still more posteriorly
the convex surface of the occipital bone. In the neighborhood of the parietal
foramen the skull is often flattened, and the name of obelion is sometimes given
to that point of the sagittal suture which lies exactly opposite to the parietal
foramen.
Internal or Cerebral Surface. — The internal surface is concave, presents depres-
sions for the convolutions of the cerebrum, and numerous furrows for the lodge-
ment of branches of the meningeal arteries. Along the middle line of this
130 THE SKELETON
surface is a longitudinal groove, narrow in front, where it commences at the
frontal crest, but broader behind, where it lodges the superior longitudinal
sinus, and by its margin affords attachment to the falx. On either side of it are
several depressions for the arachnoid villi, and at its back part the internal open-
ings of the parietal foramina. This surface is crossed, in front, by the coronal
suture; from before backward by the sagittal; behind, by the lambdoid.
The Base of the Skull (the Skull being without the Mandible).
The inferior region, or base of the skull, presents two surfaces — an internal
or cerebral, and an external or basilar.
Surfaces. Internal Upper or Cerebral Surface. — The internal or cerebral surface
(Fig. 95) presents three fossie, called the anterior, middle, and posterior fossae of the
cranium.
ANTERIOR FOSSA (fossa cranii anterior). — The anterior fossa is formed by the
orbital plates of the frontal, the cribriform plate of the ethmoid, the anterior
third of the superior surface of the body, and the upper surface of the lesser wings
of the sphenoid bone. It is the most elevated of the three fossae, convex exter-
nally where it corresponds to the roof of the orbit, concave in the median line in
the situation of the cribriform plate of the ethmoid. It is traversed by three sutures,
the ethmo-frontal, ethmo-sphenoidal, and fronto-sphenoidal, and lodges the frontal
lobes of the cerebrum. It presents, in the median line, from before backward, the
commencement of the groove for the superior longitudinal sinus and the frontal
crest for the attachment of the falx; the foramen caecum, an aperture formed
between the frontal bone and the crista galli of the ethmoid, which, if pervious,
transmits a small vein from the nose to the superior longitudinal sinus; behind the
foramen caecum, the crista galli, the posterior margin of which affords attachment
to the falx; on either side of the crista galli, the cribriform plate, which supports the
olfactory bulb, and presents three rows of foramina for the transmission of its
nervous filaments, and in front a slit-like opening for the nasal branch of the
ophthalmic division of the trigeminal nerve. On the outer side of each olfactory
groove, transmits the anterior ethmoidal vessels and the nasal nerve, which latter
runs in a depression along the surface of the ethmoid to the slit-like opening above
mentioned; while the posterior ethmoidal foramen opens at the back part of this
margin under cover of the projecting lamina of the sphenoid, and transmits the
posterior ethmoidal vessels. Farther back in the middle line is the ethmoidal spine,
bounded behind by a slight elevation, separating two shallow longitudinal grooves
which support the olfactory lobes. Behind this is a transverse sharp ridge, run-
ning outward on either side to the anterior margin of the optic foramen, and sepa-
rating the anterior from the middle fossa of the base of the skull. The anterior
fossa presents, laterally, depressions for the convolutions of the brain and grooves
for the lodgement of the anterior meningeal arteries.
MIDDLE FOSSA (fossa cranii media). — The middle fossa, deeper than the pre-
ceding, is narrow in the middle line, but becomes wider at the side of the skull. It
is bounded in front by the posterior margin of the lesser wing of the sphenoid, the
anterior clinoid process, and the ridge forming the anterior margin of the optic
groove; behind, by the superior border of the petrous portion of the temporal and
the dorsum sellae ; externally by the squamous portion of the temporal and the
anterior inferior angle of the parietal bone, and greater wing of the sphenoid. It is
traversed by four sutures, the squamo-parietal, spheno-parietal, squamo-sphenoidal,
and petro-sphenoidal. In the middle line, from before backward, is the optic groove,
THE BASE OF THE SKULL
131
behind which lies the chiasma (optic commissure) ; the groove terminates on each
side in the optic foramen, for the passage of the optic nerve and ophthalmic artery;
Groove for superior longitudinal sinus.
Grooves for anterior meningeal artery.
Foramen csecum.
Crista galli.
Slit for nasal nerve.
Groove for nasal nerve.
Anterior ethmoidal foramen.
Orifices for olfactory nerves.
Posterior ethmoidal foramen.
Ethmoidal spine.
Olfactory grooves.
Optic foramen.
Optic groove.
Olivary process.
Anterior clinoid process.
Middle clinoid process.
Posterior clinoid process.
Groove for 6th nerve.
Foramen lacerum medium.
Orifice of carotid canal.
Depression for Gasserian ganglion.
Meatus auditorius internus.
Slit for dura mater.
Superior petrosal groove.
Foramen lacerum posterius.
Antenor condyloid foramen.
Aquxductus vestibuli.
Posterior condyloid foramen.
Mastoid foramen
Posterior meningeal grooves.
FIG. 95. — Base of the skull. Inner or cerebral surface.
behind the optic groove is the olivary process and laterally the anterior clinoid pro-
cesses, to which are attached processes of the tentorium. Farther back is the sella
turcica, a deep depression which lodges the pituitary gland, bounded in front by a
132 THE SKELETON
small eminence on either side, the middle clinoid process, and behind by a broad,
square plate of bone, the dorsum sellae or dorsum ephippii, surmounted at each supe-
rior angle by a tubercle, the posterior clinoid process ; beneath the latter process is
a notch, for the abducent nerve. On each side of the sella turcica is the cavernous
groove: it is broad, shallow, and curved somewhat like the italic letter /; it com-
mences behind at the foramen lacerum medium, and terminates on the inner
side of the anterior clinoid process, and presents along its outer margin a ridge
of bone. This groove lodges the cavernous sinus, the internal carotid artery,
and the nerves of the orbit. The sides of the middle fossa are of considerable
depth; they present depressions for the convolutions of the brain and grooves
for the branches of the middle meningeal artery; the latter commence on the
outer side of the foramen spinosum, and consist of two large branches, an anterior
and a posterior; the former passing upward and forward to the anterior inferior
angle of the parietal bone, the latter passing upward and backward. The fol-
lowing foramina may also be seen from before backward: Most anteriorly is the
foramen lacerum anterius, or sphenoidal fissure (fissura orbitalis superior), formed
above by the lesser wing of the sphenoid ; below, by the greater wing; internally, by
the body of the sphenoid ; and sometimes completed externally by the orbital plate
of the frontal bone. It transmits the third, the fourth, the three branches of the
ophthalmic division of the trigeminal, the abducent nerve, some filaments from the
cavernous plexus of the sympathetic, the orbital branch of the middle meningeal
artery, a recurrent branch from the lachrymal artery to the dura, and the ophthal-
mic vein. Behind the inner extremity of the sphenoidal fissure is the foramen
rotundum, for the passage of the second division of the trigeminal or the superior
maxillary nerve; still more posteriorly is seen a small orifice, the foramen Vesalii,
an opening situated between the foramen rotundum and ovale, a little internal to
both: it varies in size in different individuals, and is often absent; when present it
transmits a small vein. It opens below into the pterygoid fossa, just at the outer
side of the scaphoid depression. Behind and external to the latter opening is the
foramen ovale, which transmits the third division of the trigeminal or the inferior
maxillary nerve, the small meningeal artery, and the small petrosal nerve.1 On the
outer side of the foramen ovale is the foramen spinosum, for the passage of the middle
meningeal artery; and on the inner side of the foramen ovale is the foramen lacerum
medium. The lower part of this aperture is filled with cartilage in the recent state.
The Vidian nerve and a meningeal branch from the ascending pharyngeal artery
pierce this cartilage. On the anterior surface of the petrous portion of the temporal
bone is seen, from without inward, the eminence caused by the projection of the
superior semicircular canal; in front of and a little outside this is a depression cor-
responding to the roof of the tympanum; the groove leading to the hiatus Fallopii,
for the transmission of the petrosal branch of the Vidian nerve and the petrosal
branch of the middle meningeal artery; beneath it, the smaller groove, for the pas-
sage of the lesser petrosal nerve; and, near the apex of the bone, the depression for
the Gasserian ganglion; and the internal orifice of the carotid canal (foramen
caroticum internum), for the passage of the internal carotid artery and carotid
plexus of nerves.
POSTERIOR FOSSA (fossa cranii* posterior). — The posterior fossa, deeply con-
cave, is the largest of the three, and situated on a lower level than either of the pre-
ceding. It is formed by the posterior third of the superior surface of the body of the
sphenoid, by the occipital, the petrous and mastoid portions of the temporal, and
the posterior inferior angle of the parietal bone; it is crossed by four sutures, the
petro-occipital, the mas to-occipital, the masto-parietal, and the basilar; and lodges
the cerebellum, pons, and oblongata. It is separated from the middle fossa in
1 See footnote, p. 95.
THE BASE OF THE SKULL 133
the median line by the dorsum sellae, and on each side by the superior border
of the petrous portion of the temporal bone. This border serves for the attach-
ment of the tentorium, is grooved for the superior petrosal sinus, and at its
inner extremity presents a notch, upon which rests the trigeminal nerve. The
circumference of the fossa is bounded posteriorly by the grooves for the lateral
sinuses. In the centre of this fossa is the foramen magnum, bounded on either
side by a rough tubercle, which gives attachment to the odontoid or check liga-
ments; and a little above these are seen the internal openings of the anterior
condyloid foramina, through which pass the hypoglossal nerves and meningeal
branches from the ascending pharyngeal arteries. In front of the foramen mag-
num is a grooved surface, formed by the basilar process of the occipital bone and
by the posterior third of the superior surface of the body of the sphenoid, which
supports the oblongata and pons, and articulates on each side with the petrous
portion of the temporal bone, forming the petro-occipital suture, the anterior half
of which is grooved for the inferior petrosal sinus, the posterior half being
encroached upon by the foramen lacerum posterius or jugular foramen (foramen
jugulare). This foramen presents three compartments: through the anterior
passes the inferior petrosal sinus; through the posterior, the lateral sinus and
some meningeal branches from the occipital and ascending pharyngeal arteries;
and through the middle, the glosso-pharyngeal, vagus, and accessory nerves.
Above the jugular foramen is the internal auditory meatus, for the facial and audi-
tory nerves and auditory artery; behind and external to this is the slit-like opening
leading into the aquaeductus vestibuli, which lodges the ductus endolymphaticus;
while between the two latter, and near the superior border of the petrous portion,
is a small, triangular depression, the remains of the floccular fossa, which lodges a
process of the dura and occasionally transmits a small vein into the substance of
the bone. Behind the foramen magnum are the inferior occipital fossae, which
lodge the hemispheres of the cerebellum, separated from one another by the inter-
nal occipital crest, which serves for the attachment of the falcula (falx cerebelli) and
lodges the occipital sinus. The posterior fossae are surmounted above by the deep
transverse grooves for the lodgement of the lateral sinuses. These channels, in
their passage outward, groove the occipital bone, the posterior inferior angle of
the parietal, the mastoid portion of the temporal, and the jugular process of the
occipital, and terminate at the back part of the jugular foramen. Where the lateral
sinus grooves the mastoid portion of the temporal bone the orifice of the mastoid
foramen may be seen. Just previous to the termination of the groove the posterior
condyloid foramen opens into it. Neither foramen is constant.
External Under or Basilar Surface (the view from below is called the norma
basalis). — The external surface of the base of the skull (Fig. 96) is extremely
irregular. It is bounded in front by the incisor teeth in the upper jaw; behind
by the superior curved lines of the occipital bone; and laterally by the alve-
olar arch, the lower border of the malar bone, the zygoma, and an imaginary line
extending from the zygoma to the mastoid process and extremity of the superior
curved line of the occiput. It is formed by the palate processes of the superior
maxillary and palate bones, the vomer, the pterygoid processes, under surface
of the great wing, spinous processes and part of the body of the sphenoid, the
under surface of the squamous, mastoid, and petrous portions of the temporal,
and the under surface of the occipital bone. The anterior part of the base of the
skull is raised above the level of the rest of this surface (when the skull is turned
over for the purpose of examination), surrounded by the alveolar process, which is
thicker behind than in front, and excavated by sixteen depressions for lodging the
teeth of the upper jaw, the cavities varying in depth and size according to the teeth
they contain. Immediately behind the incisor teeth is the anterior palatine fossa
(foramen incisivum) . At the bottom of this fossa may usually be seen four apertures :
134
THE SKELETON
two placed laterally, the foramina of Stenson, which open above, one in the floor of
each nostril, and transmit the anterior branch of the posterior palatine vessels, and
Anterior palatine fossa.
Transmits left naso-palatine nerve.
Transmits anterior palatine vessel.
Transmits right naso-palatine nerve.
Accessory palatine foramina.
Posterior nasal spine.
AZYQOS UVUL/E.
Hamular process.
•Sphenoid process of palate.
Ptery go-palatine canal.
-TENSOR TVMPANI.
Pharyngeal spine for
SUPERIOR CONSTRICTOR.
Situation of Eustachian tube and,
canal for TENSOR TVMPANI.
TENSOR PALATI.
Canal for Jacobson's nerve.
Aquseductus cochlex.
Foramen lacerum postering.
Canal for Arnold's nerve.
Auricular fissure.
FIG. 96.— Base of the skull. External surface.
THE BASE OF THE SKULL 135
two in the median line in the intermaxillary suture, the foramina of Scarpa, one
in front of the other, the anterior transmitting the left, and the posterior (the
larger) the right, naso-palatine nerve. These two lateral canals are sometimes
wanting, or they may join to form a single one, or one of them may open into one
of the lateral canals above referred to. The palatine vault is concave, uneven,
perforated by numerous foramina, marked by depressions for the palatine glands,
and crossed by a crucial suture, formed by the junction of the four bones of which
it is composed. At the front part of this surface a delicate linear suture may
frequently be seen, passing outward and forward from the anterior palatine fossa
to the interval between the lateral incisor and canine teeth, and marking off the
pre -maxillary portion of the bone. At each posterior angle of the hard palate is
the posterior palatine foramen, for the transmission of the posterior palatine vessels
and great descending palatine nerve; and running forward and inward from it a
groove, for the same vessels and nerve. Behind the posterior palatine foramen
is the tuberosity of the palate bone, perforated by one or more accessory posterior
palatine canals, and marked by the commencement of a ridge which runs trans-
versely inward, and serves for the attachment of the tendinous expansion of the
Tensor palati muscle. Projecting backward from the centre of the posterior
border of the hard palate is the posterior nasal spine, for the attachment of the
Azygos uvulae muscle. Behind and above the hard palate is the posterior aper-
ture of the nares, divided into two parts by the vomer, bounded above by the
body of the sphenoid, below by the horizontal plate of the palate bone, and lat-
erally by the internal pterygoid plate of the sphenoid. Each aperture measures
about an inch in the vertical and about half an inch in the transverse direction.
At the base of the vomer may be seen the expanded aloe of this bone, receiving
between them, on each side, the rostrum of the sphenoid. Near the lateral margins
of the vomer, at the root of the pterygoid processes, are the pterygo-palatine canals.
The pterygoid process, which bounds the posterior nares on each side, presents
near its base the pterygoid or Vidian canal (canalis pterygoideus) , for the Vidian nerve
and artery. Each process consists of two plates, which bifurcate at the extremity to
receive the tuberosity of the palate bone, and are separated behind by the ptery-
goid fossa, which lodges the Internal pterygoid muscle. The internal plate is
long and narrow, presenting on the outer side of its base the scaphoid fossa, for
the origin of the Tensor palati muscle, and at its extremity the hamular process,
around which the tendon of this muscle turns. The external pterygoid plate is
broad, forms the inner boundary of the zygomatic fossa, and affords attachment
by its outer surface to the External pterygoid muscle.
Behind the nasal fossae in the middle line is the basilar surface of the occipital
bone, presenting in its centre the pharyngeal spine, for the attachment of the
Superior constrictor muscle of the pharynx, with depressions on each side for
the insertion of the Rectus capitis anticus major*and minor. At the base of the
external pterygoid plate is the foramen ovale, for the transmission of the third divi-
sion of the trigeminal nerve, the small meningeal artery, and sometimes the small
petrosal nerve; behind this, the foramen spinosum, which transmits the middle
meningeal artery, and the prominent spinous process of the sphenoid, which gives
attachment to the internal lateral ligament of the lower jaw and the Tensor palati
muscle. External to the spinous process is the glenoid fossa, divided into two parts
by the Glaserian fissure (page 84), the anterior portion concave, smooth, bounded
in front by the eminentia articularis, and serving for the articulation of the condyle
of the lower jaw; the posterior portion rough, bounded behind by the tympanic
plate, and serving for the reception of part of the parotid gland. Emerging from
between the laminae of the vaginal process of the tympanic plate is the styloid
process, and at the base of this process is the stylo-mastoid foramen, for the exit of
the facial nerve and entrance of the stylo-mastoid artery. External to the stylo-
136 THE SKELETON
mastoid foramen is the auricular fissure, for the exit of the auricular branch of the
vagus, bounded behind by the mastoid process. Upon the inner side of the mas-
toid process is a deep groove, the digastric fossa; and a little more internally the
occipital groove, for the occipital artery. At the base of the internal pterygoid plate
is a large and somewhat triangular aperture, the foramen lacerum medium, bounded
in front by the great wing of the sphenoid, behind by the apex of the petrous por-
tion of the temporal bone, and internally by the body of the sphenoid and basilar
process of the occipital bone : it presents in front the posterior orifice of the Vidian
canal; behind, the aperture of the carotid canal. The basilar surface of this open-
ing is filled in the recent state by fibre-cartilaginous substance; across its upper
or cerebral aspect passes the internal carotid artery. External to this aperture the
petro-sphenoidal suture is observed, at the outer termination of which is seen the
orifice of the canal for the Eustachian tube and that for the Tensor tympani
muscle. Behind this suture is seen the under surface of the petrous portion of the
temporal bone, presenting, from within outward, the quadrilateral, rough surface,
part of which affords attachment to the Levator palati and Tensor tympani mus-
cles; posterior to this surface is the orifice of the carotid canal (foramen caroticum
externum) and the orifice of the aquaeductus cochleae, the former transmitting the
internal carotid artery and the ascending branches of the superior cervical ganglion
of the sympathetic, the latter serving for the passage of a small artery to and a
small vein from the cochlea. Behind the carotid canal is a large aperture, the
jugular foramen, formed in front by the petrous portion of the temporal, and behind
by the occipital; it is generally larger on the right than on the left side, and is
divided into three compartments by processes of dura. The anterior is' for the
passage of the inferior petrosal sinus; the posterior, for the lateral sinus and
some meningeal branches from the occipital and ascending pharyngeal arteries;
the central one, for the glosso-pharyngeal, vagus, and accessory nerves. On
the ridge of bone dividing the carotid canal from the jugular foramen is the
small foramen for the transmission of Jacobson's nerve; and on the wall of the
jugular foramen, near the root of the styloid process, is the small aperture for
the transmission of the vagus nerve. Behind the basilar -surface of the
occipital bone is the foramen magnum, bounded on each side by the condyles,
rough internally for the attachment of the check or odontoid ligaments, and
presenting externally a rough surface, the jugular process, which serves for the
attachment of the Rectus capitis lateralis muscle and the lateral occipito-atlantal
ligament. On either side of each condyle anteriorly is the anterior condyloid fossa,
perforated by the anterior condyloid foramen, for the passage of the hypoglossal
nerve and often a meningeal branch of the ascending pharyngeal artery. Behind
each condyle is the posterior condyloid fossa, perforated by the posterior condyloid
foramen, for the transmission of a vein to the lateral sinus. Behind the foramen
magnum is the external occipital crest, terminating above at the external occipital
protuberance, whilst on each side are seen the superior and inferior curved lines;
these, as well as the surfaces of bone between them, are rough for the attachment
of the muscles, which are enumerated on page 76.
The Lateral Region of the Skull.
The view of the lateral region of the skull from the side is known as the norma
lateralis. The lateral region is of a somewhat triangular form, the base of the tri-
angle being formed by a line extending from the external angular process of the
frontal bone along the temporal ridge backward to the outer extremity of the supe-
rior curved line of the occiput; and the sides by two lines, the one drawn down-
ward and backward from the external angular process of the frontal bone to the
angle of the lower jaw, the other from the angle of the jaw upward and back-
THE LATERAL REGION OF THE SKULL
137
ward to the outer extremity of the superior curved line. This region is divisible into
three portions — temporal fossa, mastoid portion, and zygomatic or infratemporal fossa.
The Temporal Fossa (fossa temporalis) . — The temporal fossa is bounded above
and behind by the temporal ridges, which extend from the external angular process
of the frontal upward and backward across the frontal and parietal bones, curving
downward behind to terminate in the posterior root of the zygomatic process, supra-
FIG. 97. — Side view of the skull. (Cryer.)
mastoid crest. In front it is bounded by the frontal, malar, and great wing of the
sphenoid; externally by the zygomatic arch formed conjointly by the malar and
temporal bones; below, it is separated from the zygomatic fossa by the pterygoid
ridge, seen on the outer surface of the great wing of the sphenoid. This fossa is
formed by five bones, part of the frontal, great wing of the sphenoid, parietal, squa-
mous portion of the temporal and malar bones, and is traversed by six sutures, part of
the transverse facial, spheno-malar, coronal, spheno-parietal, squamo-parietal, and
squamo-sphenoidal. The point where the coronal suture crosses the superior tem-
poral ridge is sometimes named the stephanion ; and the region where the four bones,
the parietal, the frontal, the squamous, and the greater wing of the sphenoid, meet,
at the anterior inferior angle of the parietal bone, is named the pterion. This point
is about on a level with the external angular process of the frontal bone and about
one and a half inches behind it. This fossa is deeply concave in front, convex
behind, traversed by grooves which lodge branches of the deep temporal arteries,
and filled by the Temporal muscles.
138
THE SKELETON
The Mastoid Portion. — The mastoid portion of the side of the skull is bounded
in front by the tubercle of the zygoma ; above, by a line which runs from the pos-
terior root of the zygoma to the end of the mastoid-parietal suture; behind and
below by the masto-occipital suture. It is formed by the mastoid and part of the
squamous and petrous portions of the temporal bone; its surface is convex and
rough for the attachment of muscles, and presents, from behind forward, the
mastoid foramen, the mastoid process, the external auditory meatus surrounded by
the tympanic plate, and, most anteriorly, the temporo-maxillary articulation. The
point where the posterior inferior angle of the parietal meets the occipital bone
and mastoid portion of the temporal is named the asterion.
The Zygomatic or Infratemporal Fossa (fossa infratemporalis) . — The zygo-
matic fossa is an irregularly shaped cavity, situated below and on the inner side
of the zygoma; bounded in front by the zygomatic surface of the superior maxil-
lary bone and the ridge which descends from its malar process; behind, by the
posterior border of the external pterygoid plate and the eminentia articularis;
above, by the pterygoid ridge on the outer surface of the great wing of the
sphenoid and the under part of the squamous portion of the temporal; below,
by the alveolar border of the superior maxilla; internally, by the external pterygoid
plate; and externally, by the zygomatic arch and ramus of the lower jaw (Fig. 98).
process
FIG. 98. — Zygomatic fossa.
It contains the lower part of the Temporal, the External and Internal pterygoid
muscles, the internal maxillary artery and vein, and inferior maxillary nerve and
their branches. At its upper and inner part may be observed two fissures, the
spheno-maxillary and pterygo-maxillary fissures.
The Spheno-maxillary Fissure (fissura orbitalis inferior), horizontal in direction,
opens into the outer and back part of the orbit. It is formed above by the lower
border of the orbital surface of the great wing of the sphenoid ; below, by the exter-
nal border of the orbital surface of the superior maxilla and a small part of the
palate bone; externally, by a small part of the malar bone:1 internally, it joins at
i Occasionally the superior maxillary bone and the sphenoid articulate with each other at the anterior extremity
of this fissure; the malar is then excluded from entering into its formation. — ED. of 15th English Edition.
THE ANTERIOR REGION OF THE SKULL 139
t
right angles with the pterygo-maxillary fissure. This fissure opens a communication
from the orbit into three fossae — the temporal, zygomatic, and spheno-maxillary fossa ;
it transmits the superior maxillary nerve and its orbital branch, the infraorbital
vessels, and ascending branches from the spheno-palatine or Meckel's ganglion.
The Pterygo-maxillary Fissure is vertical, and descends at right angles from the
inner extremity of the preceding; it is a V-shaped interval, formed by the diver-
gence of the superior maxillary bone from the pterygoid process of the sphenoid.
It serves to connect the spheno-maxillary fossa with the zygomatic fossa, and
transmits the internal maxillary artery.
The Spheno-maxillary or Pterygo-palatine Fossa (fossa pterygopalatina).—
The spheno-maxillary fossa is a small, triangular space situated at the angle
of junction of the spheno-maxillary and pterygo-maxillary fissures, and placed
beneath the apex of the orbit. It is formed above by the under surface of the
body of the sphenoid and by the orbital process of the palate bone; in front,
by the superior maxillary bone; behind, by the anterior surface of the base of
the pterygoid process and lower part of the anterior surface of the great wing of
the sphenoid; internally, by the vertical plate of the palate. This fossa has
three fissures terminating in it — the sphenoidal, spheno-maxillary, and pterygo-
maxillary ; it communicates with the orbit by the spheno-maxillary fissure ; with the
nasal fossie by the spheno-palatine foramen, and with the zygomatic fossa by the
pterygo-maxillary fissure. It also communicates with the cavity of the cranium,
and has opening into it five foramina. Of these, there are three on the posterior
wall: the foramen rotundum above; below and internal to this, the Vidiah canal; and
still more inferiorly and internally, the pterygo-palatine canal. On the inner wall
is the spheno-palatine foramen, by which the spheno-maxillary communicates with
the nasal fossa; and below is the superior orifice of the posterior palatine canal,
besides occasionally the orifices of the accessory posterior palatine canals. The
fossa contains the superior maxillary nerve and Meckel's ganglion, and the termi-
nation of the internal maxillary artery.
The Anterior Region of the Skull.
>
The view of the anterior region of the skull from the front is known as the
norma frontalis. It forms the face, is of an oval form, presents an irregular
surface, and is excavated for the reception of two of the organs of sense, the
eye and the nose. It is bounded above by the glabella and margins of the
orbit; below, by the prominence of the chin; on each side by the malar bone
and anterior margin of the ramus of the jaw. In the median line are seen from
above downward the glabella, and diverging from it are the superciliary ridges,
which indicate the situation of the frontal sinuses and supports the eyebrow.
Beneath the glabella is the fronto-nasal suture, the mid-point of which is termed
the nasion, and below this is the arch of the nose, formed by the nasal bones, and
the nasal processes of the superior maxillary. The nasal arch is convex from side
to side, concave from above downward, presenting in the median line the inter-
nasal suture (sutura internasalis) , formed between the nasal bones, laterally the
naso-maxillary suture (sutura nasomaxillaris) , formed between the nasal bone and
the nasal process of the superior maxillary bone. Below the nose is seen the
opening of the anterior nares, which is heart-shaped, with the narrow end
upward, and presents laterally the thin, sharp margins serving for the attach-
ment of the lateral cartilages of the nose, and in the middle line below a
prominent process, the anterior nasal spine, bounded by two deep notches.
Below this is the intermaxillary suture (sutura intermaxillaris) , and on each side
of it the incisive fossa. Beneath this fossa are the alveolar processes of the
upper and lower jaws, containing the incisor teeth, and at the lower part of the
140
THE SKELETON
median line the symphysis of the chin, the mental process, with its two mental
tubercles, separated by a median groove, and the incisive fossa of the lower jaw.
On each side, proceeding from above downward, is the supraorbital ridge,
terminating externally in the external angular process at its junction with the
malar, and internally in the internal angular process; toward the inner third of
this ridge is the supraorbital notch or foramen, for the passage of the supraorbital
vessels and nerve. Beneath the supraorbital ridge is the opening of the orbit,
bounded externally by the orbital ridge of the malar bone; below, by the orbital
ridge formed by the malar and superior maxillary bones; internally, by the nasal
process of the superior maxillary arid the internal angular process of the frontal
bone. On the outer side of the orbit is the quadrilateral anterior surface of the
malar bone, perforated by one or two small malar foramina. Below the inferior
margin of the orbit is the infraorbital foramen, the termination of the infraorbital
canal, and beneath this the canine fossa, which gives attachment to the Levator
anguli oris; still lower are the alveolar processes, containing the teeth of the upper
and lower jaws. Beneath the alveolar arch of the lower jaw is the mental foramen,
for the passage of the mental vessels and nerve, the external oblique line, and at
the lower border of the bone, at the point of junction of the body with the ramus,
a shallow groove for the passage of the facial artery.
Orbits, Orbital Cavities, or Orbital Fossae. — The orbits (from orbis, a circle)
(Fig. 99) are two quadrilateral pyramidal cavities, situated at the upper and anterior
TENDO OOULI
Groove for
facial artery
FIG. 99. — Antero-lateral region of the skull. (Cryer.)
THE ANTERIOR REGION OF THE SKULL 141
part of the face, their bases being directed forward and outward, and their apices
backward and inward, so that the axes of the two, if continued backward, would
meet over the body of the sphenoid bone. The wide orbital opening or mouth is
called the aditus orbitce. The orbit is lined with periosteum, the periorbita. Each
orbit (orbitd) is formed of seven bones, the frontal, sphenoid, ethmoid, superior
maxillary, malar, lachrymal, and palate; but three of these, the frontal, ethmoid,
and sphenoid, enter into the formation of both orbits, so that the two cavities are
formed of eleven bones only. Each cavity presents for examination a roof, a floor,
an inner and an outer wall, four angles, a circumference or base, and an apex.
The Roof (paries superior). — The roof is concave, directed downward and
slightly forward, and formed in front by the orbital plate of the frontal; behind,
by the lesser wing of the sphenoid. This surface presents internally the depres-
sion for the cartilaginous pulley of the Superior oblique muscle; externally, the
depression for the lachrymal gland; and posteriorly, the suture connecting the
frontal and lesser wing of the sphenoid.
The Floor (paries inferior). — The floor is directed upward and outward, and
is of less extent than the roof; it is formed chiefly by the orbital process of
the superior maxillary; in front, to a small extent, by the orbital process of the
rnalar, and behind, by the superior surface of the orbital process of the palate.
This surface presents at its anterior and internal part, just external to the lachrymal
groove, a depression for the attachment of the Inferior oblique muscle; externally,
the suture between the malar and superior maxillary bones ; near its middle, the infra-
orbital groove ; and posteriorly, the suture between the maxillary and palate bones.
Inner or Medial Wall (paries medialis). — The inner wall is flattened, nearly
vertical, and formed from before backward by the nasal process of the superior
maxillary, the lachrymal, os planum of the ethmoid, and a small part of the body of
the sphenoid. This surface presents the lachrymal groove and crests of the lachrymal
bone, and the sutures connecting the lachrymal with the superior maxillary, the
ethmoid with the lachrymal in front, and the ethmoid with the sphenoid behind.
Outer or Lateral Wall (paries lateralis). — The outer wall is directed forward
and inward, and is formed in front by the orbital process of the malar bone;
behind, by the orbital surface of the greater wing of the sphenoid. On it are
seen the orifices of one or two malar canals, and the suture connecting the sphenoid
and malar bones.
Angles. — The superior external angle is formed by the junction of the upper
and outer walls; it presents from before backward, the suture connecting the
frontal with the malar in front and with the great wing of the sphenoid behind;
quite posteriorly is the foramen lacerum anterius, or sphenoidal fissure, which
transmits the third, the fourth, the three branches of the ophthalmic division of the
trigeminal, the abducent nerve, some filaments from the cavernous plexus of the
sympathetic, the orbital branch of the middle meningeal artery, a recurrent
branch from the lachrymal artery to the dura, and the ophthalmic vein. The
superior internal angle is formed by the junction of the upper and inner wall, and
presents the suture connecting the frontal bone with the lachrymal in front and
with the ethmoid behind. The point of junction of the anterior border of the
lachrymal with the frontal has been named the dacryon. This angle presents two
foramina, the anterior and posterior ethmoidal foramina, the former transmitting the
anterior ethmoidal vessels and nasal nerve, the latter the posterior ethmoidal vessels.
The inferior external angle, formed by the junction of the outer wall and floor, pre-
sents the spheno-maxillary fissure, which transmits the superior maxillary nerve and
its orbital branches, the infraorbital vessels, and the ascending branches from the
spheno-palatine or Meckel's ganglion. The inferior internal angle is formed by
the union of the lachrymal bone and the os planum of the ethmoid with the
superior maxillary and palate bones.
142
THE SKELETON
Circumference. — The circumference or base of the orbit, quadrilateral in form,
is bounded above (mar go supraorbitalis) by the supraorbital ridge; below (margo
infraorbitalis) , by the anterior border of the orbital plate of the malar and supe-
rior maxillary bones; externally, by the external angular process of the frontal
and malar bones; internally, by the internal angular process of the frontal and the
nasal process of the superior maxillary. The circumference is marked by three
sutures, the fronto-maxillary internally, the fronto-malar externally, and the malo-
maxillary below; it contributes to the formation of the lachrymal groove, and
presents, above, the supraorbital notch (or foramen), for the passage of the supra-
orbital vessels and nerve.
Apex. — The apex, situated at the back of the orbit, corresponds to the optic
foramen,1 a short circular canal which transmits the optic nerve and ophthalmic
artery. It will thus be seen that there are nine openings communicating with each
orbit— viz., the optic foramen, sphenoidal fissure, spheno-maxillary fissure, supra-
orbital foramen, infraorbital canal, anterior and posterior ethmoidal foramina,
malar foramina, and the canal for the nasal duct.
PROBE FROM FRONTAL
SINUS IN THE
INFUNDIBULUM
PROBE IN N
LACHRYMAL CANAL PALATE BONE
FIG. 100. — Nasal cavity, right lateral wall, from the left. (Spalteholz.)
The Nasal Cavity (cavum nasi). — The nasal cavities or nasal fossae (Figs.
84 and 100) are two large, irregular cavities situated on either side of the middle
line of the face, extending from the base of the cranium to the roof of the
mouth, and separated from each other by a thin vertical septum, the septum of
the nose (septum nasi osseum), formed by the perpendicular plate of the ethmoid
and by the vomer. Each cavity communicates by a large aperture, the anterior
nasal aperture (apertura pyriformis),2 with the front of the face, and by the two
posterior nares (choanoe) with the naso-pharynx behind. These fossae are much
1 Quain, Testut, and others give the apex of the orbit as corresponding with the inner end of the sphenoidal
fissure. It seems better, however, to adopt the statement in the text, since the muscles of the eyeball take
origin around the optic foramen, and diverge from it to the globe of the eye. — ED. of 15th English Edition.
2 In the skull freed of soft parts, the anterior nasal cavities open in front by the apertura pyriformis. In the
skull with the soft parts in place they open by the anterior nares.
THE ANTERIOR REGION OF THE SKULL 143
narrower above than below, and in the middle than at the anterior or posterior
openings; their depth, which is considerable, is much greater in the middle than at
either extremity. " The nasal fossae are surrounded by four other fossae — above is
the cranial fossa; laterally, the orbital fossae; and below, the cavity of the mouth."1
Each nasal fossa communicates with four sinuses, the frontal above, the sphenoidal
behind, and the maxillary and ethmoidal on the outer wall. Each fossa also com-
municates with four cavities: with the orbit by the lachrymal groove, with the
mouth by the anterior palatine canal, with the cranium by the olfactory foramina,
and with the spheno-maxillary fossa by the spheno-palatine foramen ; and they occa-
sionally communicate with each other by an aperture in the septum. The bones
entering into their formation are fourteen in number: three of the cranium, the
frontal, sphenoid, and ethmoid, and all the bones of the face, excepting the malar
and lower jaw. Each cavity is bounded by a roof, a floor, an inner and an outer wall.
Upper Wall. — The upper wall, or roof (Fig. 101), is long, narrow, and horizontal
in its centre, but slopes downward at its anterior and posterior extremities; it is
formed in front by the nasal bones and nasal spine of the frontal, which are
directed downward and forward; in the middle, by the cribriform plate of the
ethmoid, which is horizontal; and behind, by the under surface of the body of the
sphenoid and sphenoidal turbinated bones, the ala of the vomer and the sphenoidal
process of the palate bone, which are directed downward and backward. This
surface presents, from before backward, the internal aspect of the nasal bones;
on their outer side, the suture formed between the nasal bone and the nasal process
of the superior maxillary; on their inner side, the elevated crest which receives the
nasal spine of the frontal and the perpendicular plate of the ethmoid, and articu-
lates with its fellow of the opposite side; whilst the surf ace of the bones is perforated
by a few small vascular apertures, and presents the longitudinal groove for the
nasal nerve; farther back is the transverse suture, connecting the frontal with the
nasal in front, and the ethmoid behind, the olfactory foramina and nasal slit on
the under surface of the cribriform plate, and the suture between it and the sphe-
noid behind; quite posteriorly are seen the sphenoidal turbinated bones, the ori-
fices of the sphenoidal sinuses, and the articulation of the alae of the vomer with
the under surface of the body of the sphenoid.
Floor (Figs. 84, 100, and 101). — The floor is flattened from before backward,
concave from side to side, and wider in the middle than at either extremity. It
is formed in front by. the palate process of the superior maxillary; behind, by the
palate process of the palate bone. This surface presents, from before backward,
the anterior nasal spine ; behind this, the upper orifices of the anterior palatine canal ;
internally, the elevated crest which articulates with the vomer; and behind, the
suture between the palate and superior maxillary bones, and the posterior nasal spine.
Inner or Medial Wall. — The inner wall, or septum (Figs. 101 and 103), is a thin
vertical partition which separates the nasal fossae from each other; it is occasionally
perforated, so that the fossae communicate, and it is frequently deflected consid-
erably to one side.2 It is formed, in front, by the crest of the nasal bones and
nasal spine of the frontal; in the middle, by the perpendicular plate of the ethmoid ;
behind, by the vomer and rostrum of the sphenoid; below, by the crests of the
superior maxillary and palate bones. It presents, in front, a large, triangular
notch, which receives the septal cartilage of the nose; and behind, the grooved
edge of the vomer. Its surface is marked by numerous vascular and nervous
canals and the groove for the naso-palatine nerve, and is traversed by sutures
connecting the bones of which it is formed.
Outer or Lateral Wall. — The outer wall (Figs. 84 and 101) is formed, in front,
by the nasal process of the superior maxillary and lachrymal bones; in the middle,
1 Howard A. Lothrop, in Annals of Surgery, May, 1903. 2 See footnote, p. 99.
144
THE SKELETON
by the ethmoid and inner surface of the body of the superior maxillary and inferior
turbinated bones; behind, by the vertical plate of the palate bone and the internal
pterygoid plate of the sphenoid. Upon this outer wall are two marked projections
UNCIFORM
PROCESS OF
ETHMOID
INFERIOR
TURBINATED
MIDDLE
TURBINATED
THIRD MOLAR
TOOTH
FIG. 101. — Coronal section of the face, passing through the third molar tooth. (Poirier and Charpy.)
of bone (Figs. 84 and 101). One is known as the inferior turbinated bone and the
other as the middle turbinated bone. The superior turbinated bones or bodies appear
BRISTLE PASSED THROUGH
INFUNDIBULUM FROM
FRONTAL SINUS TO
MIDDLE MEATUS
ANTRUM O
HIGHMOR
PROBE PASSED
THROUGH LACH-
RYMAL CANAL
RONTAL CANAL
if— NASAL CANAL
FIG. 102. — Cranial section through the frontal sinus and nasal fossa. (Poirier and Charpy.)
as less distinct bony projections. This surface presents three irregular longitudinal
passages, or meatuses, termed the superior, middle, and inferior meatuses of the
nose (Figs. 84, 101, and 102). The superior meatus (meatus nasi superior), the
THE ANTERIOR REGION OF THE SKULL
145
smallest of the three, is situated at the upper and back part of each nasal fossa, occu-
pying the posterior third of the outer wall. It is situated between the superior and
middle turbinated bones, and has opening into it two foramina, the spheno-palatine
foramina at the back of its outer wall, and the posterior ethmoidal cells at the front
part of the outer wall. The sphenoidal sinus opens into a recess, the spheno-
ethmoidal recess (recessus sphenoethmoidalis) , which is situated above and behind
the superior turbinated bone. The middle meatus (meatus nasi medius) is situated
external to the middle turbinated bone, and above the inferior turbinated bone,
ami extends from the anterior end of the inferior turbinated bone to the spheno-
palatine foramen of the outer wall of the nasal fossa. Anteriorly it terminates in
a depression, the atrium of the nasal meatus. The bulla ethmoidalis, an elevated
area disclosed by removing the middle turbinated bone. Below and in front of the
bulla is a groove, the semilunar hiatus (hiatus semilunaris), into which open the
antrum and the anterior ethmoidal . cells. The middle meatus presents in front
the orifice of the infundibulum (infundibulum ethmoidale) , by which the middle
meatus communicates with the anterior ethmoidal cells, and through these with
Crest of nasal bone,
Nasal spine of
frontal bone.
Space for triangular ;
cartilage of septum
Crest of palate bone,
•est of superior maxilla.
FIG. 103. — Inner wall of nasal fossae, or septum ol nose.
the frontal sinuses. The middle ethmoidal cells also open into this meatus, while
at the centre of the outer wall is the orifice of the maxillary antrum (hiatus maxil-
laris), which varies somewhat as to its exact position in different skulls. The
inferior meatus (meatus nasi inferior), the largest of the three, is the space between
the inferior turbinated bone and the floor of the nasal fossa. It extends along
the entire length of the outer wall of the nose, is broader in front than behind,
and presents anteriorly the lower orifice of the canal for the nasal duct (canalis
nasolacrimalis}. The anterior nares present a heart-shaped or pyriform opening
(apertura piriformis} whose long axis is vertical and narrow extremity upward.
This opening in the recent state is much contracted by the cartilages of the nose.
It is bounded above by the inferior border of the nasal bone; laterally by the thin,
sharp margin which separates the facial from the nasal surface of the superior
10
146
THE SKELETON
maxillary hone; and below by the same border, where it slopes inward to join its
fellow of the opposite side at the anterior nasal spine. The posterior nares, or
choanoe, are the two posterior oval openings of the nasal fossae, by which they
communicate with the upper part of the naso-pharynx. They are situated imme-
diately in front of the basilar process, and are bounded above by the under
surface of the body of the sphenoid and alee of the vomer; below, by the posterior
border of the horizontal plate of the palate bone; externally, by the inner surface
of the internal pterygoid plate; and internally, in the middle line, they are
separated from each other by the posterior border of the vomer.
Shape of the Skull. — Great variations in shape occur. There is a notable con-
trast between the oval or elliptical skull of a Caucasian, the pyramidal skull of an
Esquimaux, and the prognathous skull of a Negro. There are also wide differences
in skulls of persons of the same race. The skull may be dolichocephalic, that is, long
and narrow (Figs. 105 and 107); it may be brachycephalic, that is, short and round
(Figs. 104 and 106) ; it may be acrocephalic, that is, shaped like a sugar loaf. There
may be great bulging of the occiput or forehead, the forehead may be vertical or
sloped backward, and may be high or low. In many dolichocephalic skulls there is
a distinct elevation over the sagittal suture. A skull possessed of such a longitudinal
ridge is called scaphoid. The shape of a dolichocephalic skull is due to early closure
of the sagittal and metopic sutures. A skull becomes short and round because of
early closure of the coronal and lambdoidal sutures. The sugar loaf skull results
from early obliteration of the transverse and longitudinal sutures. An individual
FIG. 104. — Brachycephalic cranium.
(Poirier and Charpy.)
FIG. 105. — Dolichocephalic cranium.
(Poirier and Charpy.)
FIG. 106. — Brachycephalic cranium.
(Poirier and Charpy.)
TIG. 107. — Dolichocephalic cranium.
Poirier and Charpy.)
THE ANTERIOR REGION OF THE SKULL 147
with a long and narrow skull usually has a long, narrow face; an individual with a
short and round skull usually has a short and broad face. The head is practically
always asymmetrical, the left side, especially the frontal region of the left side, being
the larger, and the right side being the higher in a large majority of persons. The
right orbit is usually higher, and the right side of the jaw is stronger, than the left.
This asymmetry results from the habitual assumption of some one position.
Dimensions of the Skull. — The diameters of different skulls, even of those of
the same race, vary greatly. Broca estimated the mean diameters of the skull as
follows :l
MALES. FEMALES.
MEAN. Millimetres. Millimetres.
Length 182
Breadth 145
Height 132
Cranial Capacity. — Capacity is in direct ratio to dimensions. According to
AVelcker the average capacity in males is 1450 c.c., and in females is 1300 c.c.
A microcephalic skull has a capacity of less than 1350 c.c. ; a mesocephalic skull has
a capacity of from 1350 to 1450 c.c.; a megacephalic skull has a capacity of over
1450 c.c.
Indices and Angles. — The length of a diameter is of slight importance; the
relation which this length bears to other measurements may be of considerable
importance.
The Cephalic Index. — The cephalic index is the proportion borne by the greatest
breadth of the skull to the greatest length. It is used to determine the form of the
skull. The formula is as follows:
Maximum breadth XI 00
— = 1 — Hu = Cephalic index.
maximum length
The greatest length is obtained by measuring from the glabella to the occipital
point; the greatest breadth, by measuring the widest distance just above the
supramastoid ridge. A dolichocephalic skull (long antero-posterior diameter and
short transverse diameter) has a cephalic index of under 75. The mesaticephalic
skull (median head) has a cephalic index from 75 to 80. The brachycephalic
skull (short antero-posterior diameter) has a cephalic index over 80.
Index of Height. — This is the ratio of height to length. The line of height is
from the basion to the bregma. The formula for this index is as follows :
Height x 100 *
— ~. — — r = Index of height.
The Facial Index. — This is the ratio between the length and the breadth of the
face. The length is measured from the nasion to the mental point; the breadth
between the zygomatic arches. The formula is as follows:
Length x 100 ....
•j-r = Facial index.
breadth
We have also the nasal index, the orbital index, and the palatal index. Camper's
facial angle has been abandoned because of inaccuracy. This angle was obtained
by drawing one line from the middle of the external auditory meatus to the inferior
margin of the nasal septum (from the auricular point to the nasal spine), the other
from the most prominent point in the midline of the forehead to the nasal spine.
The angle formed by the meeting of these two lines varies between 62 degrees
and 85 degrees (Cunningham). The more the lower part of the face projects the
less the angle. This projection is marked in the negro races. Such a projecting
face is called prognathous.
1 Quoted by Prof. Dwight in PiersoPs Human Anatomy.
148 THE SKELETON
Flower's Gnathic Index. — This is now employed instead of Camper's facial angle.
A line is drawn from the basion to the alveolar point, and another line is drawn
between the basion and nasion. We estimate the ratio which the measurement
of the first line bears to the second. The formula is as follows:
Basi-alveolar line X 100
— r — • — , ,. — = Gnathic index,
basi-nasal line
Dwight1 tells us that an orthognathous skull has an index below 98; a mesogna-
thous skull has an index from 90 to 103; a prognathous skull has an index above 103.
For the Skull at Different Ages, see p. 102; Sexual Differences in the Skull,
p. 102; the Fontanelles, p. 102.
Surface Form. — The various bony prominences or landmarks which are to be easily felt and
recognized in the head and face, and which afford the means of mapping out the important
structures comprised in this region, are as follows:
1. Supraorbital arch. 8. Parietal eminences.
2. Internal angular process. 9. Temporal ridge.
3. External angular process. 10. Frontal eminences.
4. Zygomatic arch. 11. Superciliary ridges.
-5. Mastoid process. 12. Nasal bones.
6. External occipital protuberance. 13. Lower margin of orbit.
7. Superior curved line of occipital bone. 14. Lower jaw.
1 . The Supraorbital arches are to be felt throughout their entire extent, covered by the eye-
brows. They form the upper boundary of the circumference or base of the orbit, and separate
the face from the forehead. They are strong and arched, and terminate internally on each side
of the root of the nose in the internal angular process, which articulates with the lachrymal
bone. Externally they terminate in the external angular process, which articulates with the
malar bone, This arched ridge is sharper and more defined in its outer than in its inner half,
and forms an overhanging process which protects and shields the lachrymal gland. It thus pro-
tects the eye in its most exposed situation and in the direction from which blows are most likely
to descend. The Supraorbital arch varies in prominence in different individuals. It is more
marked in the male than in the female, and in some races of mankind than others. In the less
civilized races, as the forehead recedes backward, the Supraorbital arch becomes more prominent,
and approaches more to the characters of the monkey tribe, in which the supraorbital arches are
very largely developed, and acquire additional prominence from the oblique direction of the
frontal bone. 2. The internal angular process is scarcely to be felt. Its position is indicated
by the angle formed by the supraorbital arch with the nasal process of the superior maxillary
bone and the lachrymal bone at the inner side of the orbit. Between the internal angular pro-
cesses of the two sides is a broad surface which assists in forming the root of the nose, and
immediately above this a broad, smooth, somewhat triangular surface, the glabella, situated
between the superciliary ridges. 3. The external angular process is much more strongly marked
than the internal, and is plainly to be felt. It is formed by the junction or confluence of the supra-
orbital and temporal ridges, and, articulating with the malar bone, it serves to a very consider-
able extent to support the bones of the face. In carnivorous animals the external angular pro-
cess does not articulate with the malar, and therefore this lateral support to the bones of the face
is not present. 4. The zygomatic arch is plainly to be felt throughout its entire length, being
situated almost immediately under the skin. It is formed by the malar bone and the zygomatic
process of the temporal bone. At its anterior extremity, where it is formed by the malar bone,
it is broad and forms the prominence of the cheek; the posterior part is narrower, and termi-
nates just in front and a little above the tragus of the external ear. The lower border is
more plainly to be felt than the upper, in consequence of the dense temporal fascia being
attached to the latter, which somewhat obscures its outline. Its shape differs very much in indi-
viduals and in different races of mankind. In the most degraded type of skull — as, for instance,
in the skull of the negro of the Guinea Coast — the malar bones project forward and not outward,
and the zygoma at its posterior extremity extends farther outward before it is twisted on itself to
be prolonged, forward. This makes the zygomatic arch stand out in bold relief, and affords
greater space for the Temporal muscle. In skulls which have a more pyramidal shape, as in the
Esquimaux or Greenlander, the malar bones do not project forward and downward under the
eyes, as in the preceding form, but take a direction outward, forming with the zygoma a large,
rounded sweep or segment of a circle. Thus it happens that if two lines are drawn from the
zygomatic arches, touching the temporal ridges, they meet above the top of the head, instead of
being parallel, or nearly so, as in the European skull, in which the zygomatic arches are not
> Piersol's Human Anatomy.
THE ANTERIOR REGION OF THE SKULL 149
nearly so prominent. This gives to the face a more or less oval type. 5. Behind the ear is the
mastoid portion of the temporal bone, plainly to he felt, and terminating below in a nipple-
shaped process. Its anterior border can be traced immediately behind the concha, and its apex
is on about a level with the lobule of the ear. It is rudimentary in infancy, but gradually
develops in childhood, and is more marked in the negro than in the European. 6. The external
occipital protuberance is always plainly to be felt just at the level where the skin of the neck
joins that of the head. At this point the skull is thick for the purposes of safety, while radiating
from it are numerous curved arches or buttresses of bone which give to this portion of the
skull further security. 7. Running outward on either side from the external occipital protu-
berance is an arched ridge of bone, which can be more or less plainly perceived. This is the
superior curved line of the occipital bone, and gives attachment to some of the muscles which
keep the head erect on the spine; accordingly, we find it more developed in the negro tribes, in
whom the jaws are much more massive, and therefore require stronger muscles to prevent their
extra weight carrying the head forward. Below this line the surface of bone at the back of the
head is obscured by the overlying muscles. Above it, the vault of the cranium is thinly covered
with soft structures, so that the form of this part of the head is almost exactly that of the upper
portion of the occipital, the parietal, and the frontal bones themselves; and in bald persons,
even the lines of junction of the bones, especially the junction of the occipital and parietal at
the lambdoid suture, may be defined as a slight depression, caused by the thickening of the
borders of the bones in ihis situation. 8. In the line of the greatest transverse diameter of the
head, on each side of the middle line, are generally to be found the parietal eminences, one on
each -side of the middle line, though sometimes these eminences are not situated at the point of
the greatest transverse diameter, which is at some other prominent part of the parietal region.
They denote the point where ossification of the parietal bone began. They are much more
prominent and well-marked in early life, in consequence of the sharper curve of the bone at
this period, so that it describes the segment of a smaller circle. Later in life, as the bone grows,
the curve spreads out and forms the segment of a larger circle, so that the eminence becomes
less distinguishable. In consequence of this sharp curve of the bone in early life, the whole of
the vault of the skull has a squarer shape than it has in later life, and this appearance may per-
sist in some rickety skulls. The eminence is more apparent in the negro's skull than in that of
the European. This is due to greater flattening of the temporal fossa in the former skull to
accommodate the larger Temporal muscle which exists in these races. The parietal eminence
is particularly exposed to injury from blows or falls on the head, but fracture is to a certain
extent prevented by the shape of the bone, which forms an arch, so that the force of the blow
is diffused over the bone in every direction. 9. At the side of the head may be felt the temporal
ridge. Commencing at the external angular process, it may be felt as a curved ridge, passing
upward and then curving backward, on the frontal bone, separating the forehead from the
temporal fossa. It may then be traced passing backward in a curved direction, over the parietal
bone, and, though less marked, still generally to be recognized. Finally, the ridge curves down-
ward, and terminates in the posterior root of the zygoma, which separates the squamous from
the subcutaneous mastoid portion of the temporal bone. Sir Victor Horsley has recently shown
in an article on the "Topography of the Cerebral Cortex," that the second temporal ridge (see
page 76) can be made out on the living body. 10. The frontal eminences vary a good deal in
different individuals, being considerably more prominent in some than in others, and they are
often not symmetrical on the two sides of the body, the one being much more pronounced than
the other. This^ is often especially noticeable in the skull of the young child or infant, and
becomes less marked as age advances. The prominence of the frontal eminences depends
more upon the general shape of the whole bone than upon the size of the protuberances them-
selves. As the skull is more highly developed in consequence of increased intellectual capacity,
s:) the frontal bone becomes more upright and the frontal eminences stand out in bolder relief.
Thus they may be considered as affording, to a certain extent, an indication of the development
of the hemispheres of the brain beneath, and of the mental powers of the individual. They
are not so much exposed to injury as the parietal eminences. In falls forward the upper extrem-
ities are involuntarily thrown out, and break the force of the fall, and thus shield the frontal
bone from injury. 1 1 . Below the frontal eminences on the forehead are the superciliary ridges,
which denote the position of the frontal sinuses, and vary according to the size of the sinuses
in different individuals, being, as a rule, small in the female, absent in children, and some-
times unusually prominent in the male, when the frontal sinuses are largely developed. They
commence on either side of the glabella, and at first present a rounded form, which gradually
fades away at their outer ends. 12. The nasal bones form the prominence of the nose. They
vary much in size and shape, and to them is due the varieties in the contour of this organ and
much of the character of the face. Thus, in the Mongolian or Ethiopian they are flat, broad,
and thick at their base, giving to these races the flattened nose by which they are characterized,
and differing very decidedly from the Caucasian, in whom the nose, owing to the shape of the
nasal bones, is narrow, elevated at the bridge, and elongated downward. Below, the nasal
bones are thin and connected with the cartilages of the nose, and the angle or arch formed by
150 THE SKELETON
their union serves to throw out the bridge of the nose, and is much more marked in some indi-
viduals than others. 13. The lower margin of the orbit, formed by the superior maxillary bone
and the malar bone, is plainly to be felt throughout its entire length. It is continuous inter-
nally with the nasal process of the superior maxillary bone, which forms the inner boundary
of the orbit. At the point of junction of the lower margin of the orbit with the nasal process
is to be felt a little tubercle of bone, which can be plainly perceived by running the finger along
the bone in this situation. This tubercle serves as a guide to the position of the lachrymal sac,
which is situated above and behind it. 14. The outline of the lower jaw is to be felt throughout
its entire length. Just in front of the tragus of the external ear, and below the zygomatic arch,
the condyle can be made out. When the mouth is opened this prominence of bone can be per-
ceived advancing out of the glenoid fossa on to the eminentia articularis, and receding again
when the mouth is closed. From the condyle the posterior border of the ramus can be felt
extending down to the angle. A line drawn from the condyle to the angle would indicate the
exact position of this border. From the angle to the symphysis of the chin the lower, rounded
border of the body of the bone is plainly to be felt. At the point of junction of the two halves
of the bone is a well-marked triangular eminence, the mental process, which forms the promi-
nence of the chin.
Fixed Points for Measurement.— In order to determine the location of regions of surgical
importance within the skull (bony spaces, vessels, fissures, centres, and convolutions of the
brain) and in order to estimate cranial capacity, measurements are made and these measure-
ments are taken from fixed points. The following are the chief fixed points:
The ALVEOLAH POINT. The lowest mid-point of the alveolar process of the upper jaw.
The ASTERION. The region of the postero-lateral fontanelle, at the posterior inferior margin
of the parietal bone.
The AURICULAR POINT. The centre of the external auditory meatus.
The BASION. The middle of the anterior edge of the foramen magnum.
The BREGMA. The site of the anterior fontanelle, where the sagittal and coronal sutures meet.
The DACRYON. The point where' the frontal, the lachrymal, and the superior maxillary bones
come in contact.
The GLABELLA. Midway between the two superciliary ridges.
The GLENOID POINT. The centre of the glenoid cavity.
The GONION. The outer surface of the angle of the mandible.
The INION. The external occipital protuberance.
The LAMBDA. The point of junction of the sagittal and lambdoid sutures.
The MALAR POINT. The most prominent portion of the malar bone.
The MENTAL POINT. The point on the symphysis menti which projects most forward.
The NASION. The middle of the naso-frontal suture.
The OBELION. A point in the sagittal suture between the parietal foramina.
The OCCIPITAL POINT. The most prominent midpoint posterior. It is situated above the
inion.
The OPHRYON. The point where a line joining the summits of the orbits touches the median
line. It is the middle of the narrowest transverse diameter of the forehead.
The OPISTHION. The mid-point of the posterior margin of the foramen magnum.
The PTERION. The site of the antero-lateral fontanelle, where the frontal, parietal, squamous
portion of the temporal and greater wing of the sphenoid are in relation.
The INFERIOR STEPHANION. The point where the inferior temporal ridge meets the coronal
suture.
The SUPERIOR STEPHANION. The point where the superior temporal ridge meets the coronal
suture.
The SUBNASAL POINT. At Jhe root of the anterior nasal spine in the mid-line.
The VERTEX. The highest point of the vault of the skull.
Besides these points we use the mastoid process, the nasal spine, the zygomatic arch, the
frontal eminences, the parietal eminences, the supraorbital ridges, the superciliary ridges, the
mental process, suprameatal spine, the external and internal angular processes, and the canine
fossa.
Surgical Anatomy. — The thickness of the skull varies greatly in different regions of the same
skull and in different individuals. The average thickness of the skull-cap is about one-fifth
of an inch. The thickest portions are the occipital protuberance, the inferior portion of the
frontal bone, and the mastoid process. The thinnest portions are the occipital fossa?, the squa-
mous portion of the temporal bone, and over certain sinuses and arteries. An arrest in the
ossifying process may give rise to deficiencies or gaps, or to fissures, which are of importance
in a medico-legal point of view, as they are liable to be mistaken for fractures. The fissures
generally extend from the margin toward the centre of the bone, but gaps may be found in the
middle as well as at the edges. In course of time they may become covered with a thin lamina
of bone.
Occasionally a protrusion of the brain or its membranes may take place through one of these
THE ANTERIOR REGION OF THE SKULL 151
gaps in an imperfectly developed skull. When the protrusion consists of membranes only, and
is filled with cerebro-spinal fluid, it is called a meningocele ; when the protrusion consists of brain
as well as membranes, it is termed an encephalocele and when the protruded brain is a prolonga-
tion from one of the ventricles, and is distended by a collection of fluid from an accumulation in
the ventricle, it is termed an hydrencephalocele. This latter condition is sometimes found at the
root of the nose, where a protrusion of the anterior horn of the lateral ventricle takes place
through a deficiency of the fronto-nasal suture. These malformations are usually found in the
middle line, and most frequently at the back of the head, the protrusion taking place through
the fissures which separate the four centres of ossification from which the tabular portion of the
occipital bone is originally developed (see page 75). They most frequently occur through the
uppef part of the vertical fissure, which is the last to ossify, but not uncommonly through the
lower part, when the foramen magnum may be incomplete. More rarely these protrusions
have been met with in other situations than those above mentioned, both through normal
fissures, as the sagittal, lambdoid, and other sutures, and also through abnormal gaps and
deficiencies at the sides, and even at the base of the skull. Force may be responsible in a young
person for separating a suture. This accident, seldom met with even in the young, is only occa-
sionally encountered in older persons.
Fractures of the skull may be divided into those of the vault and those of the base. Frac-
tures of the vault are usually produced by direct violence. This portion of the skull varies in
thickness and strength in different individuals, but, as a rule, is sufficiently strong to resist a very
considerable amount of violence without being fractured. This is due to several causes: the
rounded shape of the head and its construction of a number of secondary elastic arches, each
made up of a single bone; the fact that it consists of a number of bones, united, at all events in
early life, by a sutural ligament, which acts as a sort of buffer and interrupts the continuity of
any violence applied to the skull; the presence of arches or ridges, both on the inside and outside
of the skull, which materially strengthen it; and the mobility of the head upon the spine, which
further enables it to withstand violence. The elasticity of the bones of the head is especially
marked in the skull of the child, and this fact, together with the wide separation of the indi-
vidual bones from each other, and the interposition between them of other and softer structures
render fracture of the bones of the head a very uncommon event in infants and quite young
children; as age advances and the bones become joined, fracture is more common, though still
less liable to occur than in the adult. Fractures of the vault may, and generally do, involve the
whole thickness of the bone; but sometimes one table may be fractured without any correspond-
ing injury to the other. Thus, the outer table of the skull may be splintered and driven into the
diploe, or in the frontal or mastoid regions into the frontal or mastoid cells, without any injury
to the internal table. And on the other hand, the internal table has been fractured, and por-
tions of it depressed and driven inward, without any fracture of the outer table. As a rule, in
fractures of the skull the inner table is more splintered and comminuted than the outer, and
this is due to several causes. It is thinner and more brittle; the force of the violence as it passes
inward becomes broken up, and is more diffused by the time it reaches the inner table; the
bone, being in the form of an arch, bends as a whole and spreads out, and thus presses the
particles together on the convex surface of the arch — i.e., the outer table — and forces them
asunder on the concave surface or inner table; and, lastly, there is nothing firm under the inner
table to support it and oppose the force. Fractures of the vault may be simple fissures or starred
and comminuted fractures, and these may be depressed or elevated. These latter cases of
fracture with elevation of the fractured portion are uncommon, and can only be produced by
direct wound. In comminuted fracture a portion of the skull is broken into several pieces,
the lines of fracture radiating from a centre where the chief impact of the blow was felt; if
depressed, a fissure circumscribes the radiating line, enclosing a portion of skull. If this area
is circular, it is termed a pond fracture, and would in all probability have been caused by
a round instrument, as a life-preserver or hammer; if elliptical in shape, it is termed a gutter
fracture, and would owe its shape to the instrument which had produced it, as a poker. A
fracture may take place along the line of an ossified or partly ossified suture. When a surgeon
explores the vault of the skull through a wound he must not mistake a Wormian bone for a frag-
ment produced by a fracture. A Wormian bone which may lead to mistake is encountered at
the anterior inferior angle of the parietal bone. Wormian bones are most frequently found
along the lambdoid suture.
Fractures of the base are most frequently produced by the extension of a fissure from the
vault, as in falls on the head, where the fissure starts from the part of the vault which first
struck the ground. Sometimes, however, they are caused by direct violence, when foreign
bodies have been forced through the thin roof of the orbit, through the cribriform plate of the
ethmoid from being thrust up the nose, or through the roof of the pharynx. Other cases of
fracture of the base occur from indirect violence, as in fracture of the occipital bone from impac-
tion of the spinal column against its condyles in falls on the buttocks, knees, or feet, or in cases
where the glenoid cavity has been fractured by the violent impact of the condyle of the lower jaw
against it from blows on the chin.
152 THE SKELETON
The most common place for fracture of the base to occur is through the middle fossa, and
here the fissure usually takes a fairly definite course. Starting from the point struck, which is
generally somewhere in the neighborhood of the parietal eminence, it runs downward through the
parietal bone and the squamous portion of the temporal bone and across the petrous portion of this
bone, frequently traversing and implicating the internal auditory meatus, to the middle lacerated
foramen. From this it may pass across the body of the sphenoid, through the pituitary fossa to
the middle lacerated foramen of the other side, and may indeed travel round the whole cranium,
so as to completely separate the anterior from the posterior part. The course of the fracture
should be borne in mind, as it explains the symptoms to which fracture in this region may give
rise; thus, if the fissure pass across the internal auditory meatus, injury to the facial and auditory
nerves may result, with consequent facial paralysis and deafness; or the tubular prolongation
of the arachnoid around these nerves in the meatus may be torn, and thus permit of the escape
of the cerebro-spinal fluid should there be a communication between the internal ear a'nd the
tympanum and the membrana tympani be ruptured, as is frequently the case; again, if the
fissure passes across the pituitary fossa and the muco-periosteum covering the under surface
of the body of the sphenoid is torn, blood will find its way into the pharynx and be swallowed,
and after a time vomiting of blood will result. Fractures of the anterior fossa, involving the
bones forming the roof of the orbit and nasal fossa, are generally the results of blows on the fore-
head ; but fracture of the cribriform plate of the ethmoid may be a complication of fracture of
the nasal bone. When the fracture implicates the roof of the orbit, the blood finds its way
into this cavity, and, travelling forward, appears as a subconjunctival ecchymosis. Subcon-
junctival ecchymosis can also be caused by fracture of the malar bone. If the roof of the nasal
fossa be fractured, the blood escapes from the nose. In rare cases there may be also escape
of cerebro-spinal fluid from the nose where the dura and arachnoid have been torn. In frac-
tures of the posterior fossa extravasation of blood takes place beneath the deep fascia and
discoloration of the skin is soon observed in the course of the posterior auricular artery, the dis-
coloration first appearing in the skin over the tip of the mastoid process of the temporal bone
(Battle's sign). Some of the blood which was extra vasated beneath the deep fascia approaches
the surface through the openings in the deep fascia for the passage of vessels and nerves.
The bones of the skull are frequently the seat of nodes, and not uncommonly necrosis results
from this cause, also from injury. Necrosis may involve the entire thickness of the skull, but
is usually confined to the external table. Necrosis of the internal table alone is rarely met with.
The bones of the skull are also sometimes the seat of sarcomatous tumor.
The skull in rickets is peculiar: the forehead is high, square, and projecting, and the antero-
posterior diameter of the skull is long in relation to the transverse diameter. The bones of the
face are small and ill-developed, and this gives the appearance of a larger head than actually
exists. The bones of the head are often thick, especially in the neighborhood of the sutures,
and the anterior fontanelle is late in closing, sometimes remaining unclosed till the fourth year.
The condition of craniotabes has by some been also believed to be the result of rickets, by others
is believed to be due to inherited syphilis. In all probability it is due to both. In these cases
the bone undergoes atrophic changes in patches, so that it becomes greatly thinned in places,
generally where there is pressure, as from the pillow or nurse's arm. It is, therefore, usually
met with in the parietal bone and vertical plate of the occipital bone.
In congenital syphilis deposits of porous bone are often found at the angles of the parietal
bones and two halves of the frontal bone which bound the anterior fontanelle. These deposits
are separated by the coronal and sagittal sutures, and give to the skull an appearance like a hot
Cross bun. They are known as Parrot's nodes, and such a skull has received the name of nati-
form, from its fancied resemblance to the buttocks. When the surgeon wishes to effect an entrance
into the interior of the -mastoid antrum (Fig. 108) he applies his bur or gouge in the suprameatal
triangle 1 cm. posterior to the suprameatal spine, being careful to keep below the posterior root of
the zygoma and the level of the superior wall of the bony meatus. If the instrument is entered
at a higher level it will open the cerebral cavity; the instrument should be carried inward, for-
ward, and a little upward, that is, in the direction of the auditory canal. The antrum is usually
reached after the penetration of from 1 to 1£ cm. of bone. The depth at which the antrum is sit-
uated is not constant. "It is safe to say that if the instrument penetrates deeper than 1 \ cm. and
be directed too far forward or downward, the horizontal semicircular canal or the aquseductus
Fallopii will be encountered. If the former were opened in a purulent otitis media the pus
would travel along it to the vestibule and from there into the internal auditory meatus, pro-
ducing a pachymeningitis or extradural (epidural) abscess of the posterior fossa of the skull ;
or from the vestibule through the perpendicular semicircular canal, which if accompanied by
erosion of its bony covering would lead to involvement of the meninges of the middle fossa;
the same would hold good for the posterior semicircular canal, affecting the posterior fossa. If
the latter (the aquaeductus Fallopii) were opened an inflammation of the facial nerve which is
contained therein would result, producing paralysis of that side of the face. The inflammatory
process might also find its way through the entire canal to the internal auditory meatus, caus-
ing a pachymeningitis or extradural abscess as mentioned above; or, travelling along the nerve
THE ANTERIOR REGION OF THE SKULL
153
to its cerebral attachment, would produce a meningitis or subdural (intradural) abscess. The
direction of the penetrating instrument must also be forward, in order to avoid injuring the
lateral sinus" ("Anatomy and Surgery of
the Temporal Bone," by A. E. Schmitt,
M.D., American Journal of the Mcilii-al
Sciences, April, 1903). In the operation
for infective thrombosis of the lateral
sinus the sinus is .deliberately exposed
and opened (Fig. 108).
Hartley divides the mastoid process
into four parts as follows: The upper
margin is the posterior root of the zygoma.
The anterior margin is the anterior
border of the mastoid. The posterior
margin is a vertical line dropped from
the masto-occipital junction. The lower
margin is an imaginary line backward
from the mastoid tip. This space is
divided into four equal parts. Points
upon it may be designated as on a map.
Take the left side for demonstration.
An opening in the N. W. quadrant enters
the antrum, one into the N. E. quad-
rant exposes the lateral sinus, one into
FIG. 108.— -Division of the mastoid process into four equal
the b. W. quadrant enters mastoid cells, parts. An opentog in th«npper»nterior quadrant reachee the
and a superficial one into the S E. mastoid antrum ; into the upper posterior quadrant reaches
. , 11 i j ' the lateral sinus; the lower anterior quadrant into mastoid
quadrant enters mastoid cells, but a deep cells; a superficial opening into the lower posterior quadrant
one exposes the descending Portion of reaches mastoid cells; a deep opening reaches the descending
, limb of the lateral sinus. (A. E. Schmitt.)
the lateral sinus. When pus breaks
through the mastoid process it may enter the sheath of the Digastric or Sterno-cleido-mastoid
muscle and point a considerable distance away from the bone, Bezold's abscess.
In connection with the bones of the face a common malformation is cleft palate, owing to
the non-union of the palatal processes of the maxillary or pre-oral arch. This cleft may involve
the whole or only a portion of the hard palate, and usually involves the soft palate also. The
cleft is in the middle line, except it involves the alveolus in front, when it follows the suture
between the main portion of the bone and the pre-maxillary bone. Sometimes the cleft runs
on either side of the pre-maxillary bone, so that this bone is quite isolated from the maxillary
bones and hangs from the end of the vomer. In such a case the pre-maxillary bone usually
contains the germs of the central incisors only. In some cases there is no pre-maxillary bone
and the great gap in the lip is in the median line. Cleft palate (Fig. 92) is usually associated
with hare-lip, which, when single, is almost always on one side, corresponding to the position
of the suture between the lateral incisor and canine tooth. Some few. cases of median hare-
lip have been described. In double hare-lip there is a cleft on each side of the middle line (see
page 111).
The outlines and the height of the arch of the palate vary greatly in different persons. A
narrow palate with a high arch is common in idiots and certain degenerates.
The bones of the face are sometimes fractured as the result of direct violence. The two
most commonly broken are the nasal bone and the mandible, and of these the latter is by
far the most frequently fractured of all the bones of the face. Fracture of the nasal bone is
for the most part transverse, and takes place about half an inch from the free margin. The
broken portion may be displaced backward or more generally to one side by the force which
produced the lesion, as there are no muscles here which can cause displacement. The malar
bone is probably never broken alone; that is to say, unconnected with a fracture of the other
bones of the face. The zygomatic arch is occasionally fractured, and when this occurs from
direct violence, as is usually the case, the fragments may be displaced inward. This lesion is
often attended with great difficulty or even inability to open and shut the mouth, and this has
been stated to be due to the depressed fragments perforating the temporal muscle, but would
appear rather to be caused by the injury done to the bony origin of the Masseter muscle.
Fractures of the superior maxilla may vary much in degree, from the chipping off of a portion
of the alveolar arch, a frequent accident when the "old key" instrument was used for the
extraction of teeth, to an extensive comminution of the whole bone from severe violence, as
the kick of a horse. The most common situation for a fracture of the mandible bone is in the
neighborhood of the canine tooth, as at this spot the jaw is weakened by the deep socket for
the fang of this tooth; it is next most frequently fractured at the angle; then at the symphysis,
and finally the neck of the condyle or the coronoid process may be broken. Occasionally a
double fracture may occur, one in either half of the bone. The fractures are usually compound,
154 THE SKELETON
from laceration of the mucous membrane covering the gums. The displacement is mainly the
result of the same violence as produced the injury, but may be further increased by the action
of the muscles passing from the neighborhood of the symphysis to the hyoid bone.
The superior and inferior maxillary bones are both of them frequently the seat of necrosis,
though the disease affects the lower much more frequently than the upper jaw. It may be the
result of periostitis, from tooth irritation, injury, or the action of some specific poison, as syphilis,
or from salivation by mercury; it not infrequently occurs in children after attacks of the exan-
thematous fevers, and a special form occurs from the action of the fumes of phosphorus in
persons engaged in the manufacture of matches.
Tumors attack the jaw bones not infrequently, and these may be either innocent or malig-
nant: in the upper jaw cysts may occur in the antrum, constituting the so-called dropsy of the
antrum; or, again, cysts may form in either jaw in connection with the teeth: either cysts con-
nected with the roots of fully developed teeth, the "dental cyst;" or cysts connected with im-
perfectly developed teeth, the "dentigerous cyst." Solid innocent tumors include the fibroma,
the chondroma, and the osteoma. Of malignant tumors there are the endotheliomata, the
sarcomata, and the epitheliomata. The sarcomata are of various kinds, the spindle-celled,
the round-celled, which are of a very malignant character, and the myeloid sarcomata, prin-
cipally affecting the alveolar margin of the bone. Of the epitheliomata we find the squamous
variety spreading to the bone from the palate or gum, and the cylindrical epithelioma origin-
ating in the antrum or nasal fossae.
Both superior and inferior maxillary bones occasionally require excision for tumors and in
some other conditions. The upper jaw is removed by an incision from the inner canthus of the
eye, along the side of the nose, round the ala, and down the middle line of the upper lip. A
second incision is carried outward from the inner canthus of the line along the lower margin of
the orbit as far as the prominence of the malar bone. The flap thus formed is reflected outward
and the surface of the bone exposed, and the central incisor of the diseased side is removed.
The connections of the bone to the other bones of the face are then divided with a narrow saw and
bone-cutting forceps. They are (1) the junction with the malar bone, passing into the spheno-
maxillary fissure; (2) the nasal process; a small portion of its upper extremity, connected with the
nasal bone in front, the lachrymal bone behind, and the frontal bone above, being left; (3) the
connection with the bone on the opposite side and the palate in the roof of the mouth. The
bone is now firmly grasped with lion-jaw forceps, and by means of a rocking movement upward
and downward the remaining attachments of the orbital plate with the ethmoid and the
back of the bone with the palate, broken through. The soft palate is first separated from
the hard with a scalpel, and is not removed. Occasionally in removing the upper jaw it
will be found that the orbital plate can be spared, and this should always be done if possible.
A horizontal saw-cut is to be made just below the infraorbital foramen and the bone cut through
with a chisel and mallet. Lockwood has pointed out that in removing the upper jaw the sur-
geon must be careful in dividing the nasal process of the superior maxilla to preserve the inter-
nal orbital or palpebral ligament (Tendo oculi), because this ligament arises from the palpebral
fascia, and if it is interfered with the eye will inevitably drop downward. Removal of one-half
of the lower jaw is sometimes required. If possible, the section of the bone should be made
to one side of the symphysis, so as to save the genial tubercles and the origin of the genio-hyo-
glossus muscle, as otherwise the tongue tends to fall backward and may produce suffocation.
Having extracted the central or preferably the lateral incisor tooth, a vertical incision is made
down to the bone, commencing at the free margin of the lip, and carried to the lower border
of the bone; it is then carried along its lower border to the angle and up the posterior margin
of the ramus to a level with the lobule of the ear. The flap thus formed is raised by separating
all the structures attached to the outer surface of the bone. The jaw is now sawn through
at the point where the tooth has been extracted, and the knife passed along the inner side of
the jaw, separating the structures attached to this surface. The jaw is then grasped by the
surgeon and strongly depressed, so as to bring down the coronoid process and enable the operator
to sever the tendon of the Temporal muscle. The jaw can be now further depressed, care being
taken not to evert it nor rotate it outward, which would endanger the internal maxillary artery,
and the External pterygoid muscle is torn through or divided. The capsular ligament is now
opened in front and the lateral ligaments divided, and the jaw removed with a few final touches
of the knife.
The antrum of Highmore occasionally requires tapping for suppuration. This may be done
through the socket of a tooth, preferably the first molar, the fangs of which are most intimately
connected with the antrum, or through the facial aspect of the bone above the alveolar process.
This latter method does not perhaps afford such efficient drainage, but there is less chance of
food finding its way into the cavity. The operation may be performed by incising the mucous
membrane above the second molar tooth, and driving a trocar or any sharp-pointed instrument
into the cavity.
155
THE HYOID OR LINGUAL BONE (OS HYOIDEUM).
The hyoid bone (Fig. 109) is named from its resemblance to the Greek upsilon;
it is also called the lingual bone, because it supports the tongue and gives attach-
ment to its numerous muscles. It is a bony arch, shaped like a horseshoe, and
consisting of five segments : a body, two greater cornua, and two lesser cornua. It
is suspended from the tip of the styloid processes of the temporal bone by liga-
mcntous bands, the stylo-hyoid ligaments.
Body (corpus ossei hyoidei). — The body, or basi-hyal, forms the central part
of the bone, and is of a quadrilateral form.
Surfaces. — Its anterior surface (Fig. 109), convex, directed forward and upward,
is divided into two parts by a vertical ridge which descends along the median
line and is crossed at right angles by a horizontal ridge, so that this surface is
divfded into four spaces or depressions. At the point of meeting of these two lines
is a prominent elevation, the tubercle. The portion above the horizontal ridge is
directed upward, and is sometimes described as the superior border. The anterior
surface gives attachment to the Genio-hyoid in the greater part of its extent ; above,
to the Genio-hyo-glossus; below, to the Mylo-hyoid, Stylo-hyoid, and aponeurosis of
the Digastric (suprahyoid aponeurosis); and between these to part of the Hyo-
glossus. The posterior surface is smooth, concave, directed backward and down-
ward, and separated from the epiglottis by the thyro-hyoid membrane and by a
quantity of loose areolar tissue. The lateral surfaces after middle life are joined
to the greater cornua. In early life they are connected to the cornua by carti-
laginous surfaces, and held together by ligaments, and occasionally a synovial
membrane is found between them.
Borders. — The superior border is rounded, and gives attachment to the thyro-
hyoid membrane, part of the Genio-hyo-glossi and Chondro-glossi muscles. The
inferior border gives attachment, in front, to the Sterno-hyoid ; behind, to the Omo-
hyoid and to the part of the Thyro-
hyoid at its junction with the great
cornu. It also gives attachment to
the Levatore glandular thyroideae
when this muscle is present.
Greater Gornua (cornua major a) .
-The greater cornua or thyro-hyals
project backward from the lateral
surfaces of the body; they are flat-
tened from above downward, di-
minish in size from before back-
ward, and terminate posteriorly in
a tubercle for the attachment of
,l | 1,1 1 • 1 !• GENIO-HYOID. STERNO-HYOID.
the lateral thyro-hyoid ligament. FIG. 109.-Hyoid bone. Anterior surface. (Enlarged.)
The outer surf ace gives attachment
to the Hyo-glossus, their upper border to the Middle constrictor of the pharynx,
their lower border to part of the Thyro-hyoid muscle.
Lesser Gornua (cornua minora). — The lesser cornua, or cerato-hyals, are two
small, conical-shaped eminences attached by their bases to the angles of junc-
tion between the body and greater cornua, and giving attachment by their apices
to the stylo-hyoid ligaments.1 The smaller cornua are connected to the body of
the bone by a distinct diarthrodial joint, which usually persists throughout life,
but occasionally becomes ankylosed.
1 These ligaments in many animals are distinct bones, and in man are occasionally ossified to a certain extent. —
ED. of 15th English Edition.
MYLO-HYOID.
156 THE SKELETON
Development. — By five centres: one for the body, and one for each cornu.
Ossification commences in the body about the eighth month, and in the greater
cornua toward the end of foetal life. Ossification of the lesser cornua commences
some years after birth. Sometimes there are two centres for the body.
Attachment of Muscles. — Sterno-hyoid, Thyro-hyoid, Omo-hyoid, aponeurosis
of the Digastric, Stylo-hyoid, Mylo-hyoid, Genio-hyoid, Genio-hyo-glossus, Chon-
dro-glossus, Hyo-glossus, Middle constrictor of the pharynx, and occasionally a
few fibres of the Inferior lingualis. It also gives attachment to the thyro-hyoidean
membrane and the stylo-hyoid, thyro-hyoid, and hyo-epiglottic ligaments.
Surface Form. — The hyoid bone can be felt in the receding angle below the chin, and the
finger can be carried along the whole length of the bone to the greater corhu, which is situated
just below the angle of the jaw. This process of bone is best perceived by making pressure on
one cornu, and so pushing the bone over to the opposite side, when the cornu of this side will
be distinctly felt immediately beneath the skin. This process of bone is an important landmark
in ligature of the lingual artery.
Surgical Anatomy. — The hyoid bone is occasionally fractured, generally from direct vio-
lence, as in the act of garroting or throttling. It is frequently found broken in those who have
been hung. The great cornu is the part of the bone most frequently broken, but sometimes
the fracture takes place through the body of the bone. In consequence of the muscles of the
tongue having important connections with this bone, there is great pain upon any attempt being
made to move the tongue, as in speaking or swallowing.
THE THORAX.
The thorax, or chest, is an osseo-cartilaginous cage the cavity of which (cavwn
thoracis) contains and protects the principal organs of respiration and circula-
tion. It is conical in shape, being narrow above and broad below, flattened
from before backward, and longer behind than in front. It is somewhat
reniform on transverse section.
Boundaries. — The posterior surf ace is formed by the twelve thoracic vertebrae and
the posterior part of the ribs. It is concave from above downward, and presents
on each side of the middle line a deep groove, the vertebral groove, in conse-
quence of the direction backward and outward which the ribs take from their
vertebral extremities to their angles. The anterior surface is flattened or slightly
convex, and inclined forward from above downward. It is formed by the sternum
and costal cartilages. The lateral surfaces are convex; they are formed by the
ribs, separated from each other by spaces. Each space is called an intercostal
space (spatium inter costale). These are eleven in number, and are occupied by
the intercostal muscles.
The superior or upper opening or aperture of the thorax, the inlet (apertura
thoracis superior}, is reniform in shape, being broader from side to side than
from before backward. It is -formed by the first thoracic vertebra behind, the
upper margin of the sternum in front, and the first rib on each side. It slopes
downward and forward, so that the anterior part of the ring is on a lower level
than the posterior. The antero-posterior diameter is about two inches, and the
transverse about four. The inferior or lower opening (apertura thoracis inferior]
is formed by the twelfth thoracic vertebra behind, by the twelfth ribs at the sides,
and in front by the cartilages of the eleventh, tenth, ninth, eighth, and seventh
ribs, which ascend on either side and form an angle, the subcostal angle (angulus
infrasternalis) , from the apex of which the ensiform cartilage projects. It is
wider transversely than from before backward. It slopes obliquely downward
and backward, so that the cavity of the thorax is much deeper behind than in
front. The Diaphragm closes in the opening forming the floor of the thorax.
In the female the thorax differs as follows from the male: 1. Its general capa-
city is less. 2. The sternum is shorter. 3. The upper margin of the sternum
THE STERN&M 157
is on a level with the lower part of the body of the third thoracic vertebra, whereas
in the male it is on a level with the lower part of the body of the second thoracic
vertebra. 4. The upper ribs are more movable, and so allow a greater enlarge-
ment of the upper part of the thorax than in the male.
The Sternum or Breast Bone.
The sternum (arepvov, the chest), or breast bone (Figs. 110, 111), is a flat,
narrow bone, situated in the median line of the front of the chest, and con-
sisting, in the adult, of three portions. It has been likened to an ancient
sword; the upper piece, representing the handle, is termed the manubrium
sterni (presternum); the middle and largest piece, which represents the chief
part of the blade, is termed the gladiolus (mesosternum or corpus sterni); and
the inferior piece, which is likened to the point of the sword, is termed the
ensiform or xiphoid process or appendix (processus xiphoideus or metasternum) .
In early youth the sternum is composed of six pieces or sternebra. In adult life
the upper piece remains as the manubrium; the inferior piece remains as the
xiphoid; and the other four pieces fuse together to form the gladiolus. In its
natural position its inclination is oblique from above downward and forward. It
is slightly convex in front, concave behind, broad above, becoming narrowed at
the point where the first and second pieces are connected, after which it again
widens a little, and is pointed at its extremity. Its average length in the adult is
about seven inches, being rather longer in the male than in the female. At the
junction of the manubrium and gladiolus is a distinct angle, the angulus sterni
(angle of Ludovic or angle of Louis), the manubrium looking forward, the
gladiolus also looking forward, but to a less degree. • This angle is on a level
with the second rib, and is produced by retraction of the upper portion of the
thorax.
First Piece. — The first piece of the sternum, or the manubrium sterni (pre-
sternum), is of a somewhat triangular form, broad and thick above, narrow
below at its junction with the middle piece.
Surfaces. — Its anterior surface, convex from side to side, concave from above
downward, is smooth, and affords attachment on each side to the Pectoralis
major and sternal origin of the Sterno-cleido-mastoid muscle. In well-marked
bones the ridges limiting the attachment of these muscles are very distinct. Its
posterior surface, concave and smooth, affords attachment on each side to the
Sterno-hyoid and Sterno- thyroid muscles.
Borders. — The superior border, the thickest, presents at its centre the pre-sternal
notch (incisura jugularis), and on each side an oval articular surface, the
clavicular facet (incisura clavicularis) , directed upward, backward, and outward,
for articulation with the sternal end of the clavicle. The inferior border presents
an oval, rough surface, covered in the recent state with a thin layer of cartilage,
for articulation with the second portion of the bone (synchondrosis sternalis).
The junction of the manubrium with the gladiolus is marked by a transverse
ridge, which corresponds to the attachment on each side of the cartilage of
the second rib. The lateral borders are marked above by a depression (incisura
costalis I) for the first costal cartilage, and below by a small facet, which, with a
similar facet on the upper angle of the middle portion of the bone, forms a
notch (incisura costalis II) for the reception of the costal cartilage of the second
rib. These articular surfaces are separated by a narrow, curved edge, which
slopes from above downward and inward.
Second Piece. — The second piece of the sternum, the corpus sterni or gladiolus
(mesosternum), considerably longer, narrower, and thinner than the first piece, is
broader below than above.
158
THE SKELETON
STERNO-CLEIDOMASTOID."^
SUBOLAVIU8.
FIG. 110. — Sternum and costal cartilages.
FIG. 111. — Posterior surface of sternum.
THE STERNUM 159
Surfaces. — Its anterior surface (planum sternale) is nearly flat, directed upward
and forward, and marked by three transverse lines which cross the bone opposite
the third, fourth, and fifth articular depressions. These lines are produced by the
union of the four separate pieces of which this part of the bone consists at an early
period of life. At the junction of the third and fourth pieces is occasionally seen
an orifice, the sternal foramen; it varies in size and form in different individuals,
and pierces the bone from before backward. This surface affords attachment
on each side to the sternal origin of the Pectoralis major. The posterior surface,
slightly concave, is also marked by three transverse lines, but they are less dis-
tinct than those in front: this surface affords attachment below, on each side,
to the Triangularis sterni muscle, and occasionally presents the posterior opening,
of the sternal foramen.
Borders. — The superior border presents an oval surface for articulation with the
manubrium. The inferior border is narrow, and articulates with the ensiform
appendix. Each lateral border presents, at each superior angle, a small facet,
which, with a similar facet on the manubrium, forms a cavity for the cartilage of
the second rib; the four succeeding angular depressions receive the cartilages of
the third, fourth, fifth, and sixth ribs; whilst each inferior angle presents a small
facet, which, with a corresponding one on the ensiform appendix, forms a notch
for the cartilage of the seventh rib. These articular depressions are known as
incisurce costales. They are separated by a series of curved interarticular inter-
vals, which diminish in length from above downward, and correspond to the
intercostal spaces. Most of .the cartilages belonging to the true ribs, as will be
seen from the foregoing description, articulate with the sternum at the line of
junction of two of its primitive component segments. This is well seen in many
of the lower animals, where the separate parts of the bone remain ununited
longer than in man. In this respect a striking analogy exists between the mode
of connection of the ribs with the vertebral column and the connection of the
costal cartilages with the sternum.
Third Piece. — The third piece of the sternum, the ensiform or xiphoid appendix
(processus xiphoideus or metasternum) , is the smallest of the three; it is thin and
elongated in form, cartilaginous in structure in youth, but more or less ossified
at its upper part in the adult.
Surfaces. — Its anterior surface affords attachment to the chondro-xiphoid
ligament; its posterior surface, to some of the fibres of the Diaphragm and
Triangularis sterni muscles; its lateral borders, to the aponeurosis of the abdom-
inal muscles. Above it articulates with the lower end of the gladiolus, and at each
superior angle presents a facet (incisura costalis VII), for the lower half of the
cartilage of the seventh rib; below, by its pointed extremity, it gives attachment
to the linea alba. This portion of the sternum is very various in appearance,
being sometimes pointed, broad, and thin, sometimes bifid or perforated by a
round hole, occasionally curved or deflected considerably to one or the other side.
Structure. — The bone is composed of delicate cancellous structure, covered by
a thin layer of compact tissue, which is thickest in the manubrium between the
articular facets for the clavicles.
Development. — The cartilaginous sternum originally consists of two bars, situ-
ated one on either side of the mesial plane and connected with the rib cartilages of
its own side. These two bars fuse with each other along the middle line, and
the bone, including the ensiform appendix, is developed by six centres: one for the
first piece or manubrium, four for the second piece or gladiolus, and one for the
ensiform appendix. Up to the middle of fretal life the sternum is entirely car-
tilaginous, and when ossification takes place the ossific granules are deposited in
the middle of the intervals between the articular depressions for the costal car-
tilages, in the following order (Fig. 112): In the first piece, between the fifth and
sixth months; in the second and third, between the sixth and seventh months; in
160
THE SKELETON
the fourth piece, at the ninth month; in the fifth, within the first year or between
the first and second years after birth; and in the ensiform appendix, between the
second and the seventeenth or eighteenth years, by a single centre which makes
its appearance at the upper part and proceeds gradually downward. To these
may be added the occasional existence, as described by Breschet, of two small
episternal centres, which make their appearance one on each side of the pre-sternal
notch. They are probably vestiges of the episternal bone of the monotremata
and lizards. It occasionally happens that some of the segments are formed from
more than one centre, the number and position of which vary (Fig. 114). Thus,
the first piece may have two, three, or even six centres. When two are present,
they are general y situated one above the other, the upper one being the larger;1
the second piece has seldom more than one; the third, fourth, and fifth pieces
are often formed from two centres placed laterally, the irregular union of which
will serve to explain the occasional occurrence of the sternal foramen (Fig. 113),
1 for 1st piece \ 5_fi<ft monthfoetal.
or manubnum )
4 for 2nd piece
or gladiolus
6-7th month.
4 9th month.
5 1st year after
birth.
1 for ensiform \2ndtol8thye
cartilage )
FIG. 112. — Development of the sternum by six
centres. Time of appearance.
) Rarely unite,
} except in old age.
and the 25th year.
Soon after puberty.
Partly cartilaginous to
advanced life.
FIG. 113. — Time of union of sternum.
for first piece, two or more centres.
for second piece, usually one.
for third "I
for fourth }• 2, placed laterally,
for fifth J
Arrest of development
of lateral pieces, producing
FIG. 114. — Peculiarities in number of centres of
sternum.
-Sternal fissure, and
.Sternal foramen.
FIG. 115. — Peculiarities in mode of union
of sternum.
or of the vertical fissure which occasionally intersects this part of the bone (Fig. 113) ,
and which is further explained by the manner in which the cartilaginous matrix,
in which ossification takes place, is formed. Union of the various centres of the
gladiolus commences about puberty, from below, and proceeds upward, so that by
the age of twenty-five they are all united, and this portion of bone consists of one
piece. The ensiform cartilage becomes joined to the gladiolus about forty. The
manubrium is occasionally but seldom joined to the gladiolus in advanced life
1 Sir George Humphry states that this is "probably the more complete condition." — ED. of 15th English Edition.
THE RIBS 161
by bone. When this union takes place, however, it is generally only superficial,
a portion of the centre of the sutural cartilage remaining unossified.
Articulations. — With the clavicles and seven costal cartilages on each side.
Attachment of Muscles. — To nine pairs and one single muscle: the Pectoralis
major, Sterno-cleido-mastoid, Sterno-hyoid, Stern o-thyroid, Triangularis sterni,
aponeuroses of the Obliquus externus, Obliquus internus, Transversalis, Rectus
muscles, and Diaphragm.
The Eibs (Costae).
The ribs are elastic arches of bone, which form the chief part of the thoracic
walls. They are twelve in number on each side; but this number may be in-
creased by the development of a cervical or lumbar rib, or may be diminished
to eleven. The first seven are connected behind with the spine and in front
with the sternum, through the intervention of the costal cartilages; they are
called true, sternal, or vertebro-sternal ribs (costae verae).1 The remaining five are
false ribs (costae spuriae) ; of these, the first three have their cartilages attached to
the cartilage of the rib above, and are called the vertebro-chondral ribs; the last
two are free at their anterior extremities; they are termed floating or vertebral
ribs. The ribs vary in their direction, the upper ones being less oblique than
the lower. The extent of obliquity reaches its maximum at the ninth rib, and
gradually decreases from that rib to the twelfth. The ribs are situated one be-
low the other in such a manner that spaces are left between them. Each space
is called an intercostal space (spatium intercostale) . The length of these spaces
corresponds to the length of the ribs and their cartilages; their breadth is greater
in front than behind, and between the upper than between the lower ribs. The
ribs increase in length from the first to the seventh, when they again diminish
to the twelfth. In breadth they decrease from above downward; in the upper
ten the greatest breadth is at the sternal extremity.
Common Characters of the Ribs.
A rib from the middle of the series should be taken in order to study the
common characters of the ribs (Figs. 116, 117, and 11'8). Each rib presents two
extremities, a posterior or vertebral, an anterior or sternal, and an intervening
portion — the body or shaft.
Posterior Extremity. — The posterior or vertebral extremity presents for ex-
amination a head, neck, and tuberosity.
The Head (capitidum costae}. — The head (Fig. 118) is marked by a kidney
shaped articular surface, divided by a horizontal ridge (crista capituli) into two
facets for articulation with the costal cavity formed by the junction of the bodies
of two contiguous thoracic vertebrae; the upper facet is small, the inferior one
of larger size; the ridge separating them serves for the attachment of the inter-
articular ligament.
The Neck (collum costae). — The neck is that flattened portion of the rib which
extends outward from the head; it is about an inch long, and is placed in front
of the transverse process of the lower of the two vertebra? with which the head
articulates. Its anterior surface is flat and smooth, its posterior surface is rough
for the attachment of the middle costo-transverse ligament, and is perforated by
numerous foramina, the direction of which is less constant than those found on
the inner surface of the shaft. Of its two borders the superior border presents
a rough crest (crista colli costae) for the attachment of the anterior costo-trans-
verse ligament; its inferior border is rounded. On the 'posterior surface of the
1 Sometimes the eighth rib cartilage articulates with the sternum; this condition occurs more frequently on the
right than on the left side. — ED. of 15th English Edition.
11
THE SKELETON
neck, just where it joins the shaft, and nearer the lower than the upper border,
is an eminence — the tuberosity, or tubercle.
Angle.-
— ^
/Tuberosity,
Articular part of tuberosity.''
iNeck.
-Subcostal groove
Head.'
Tuberosity (tuberculum costae). — The tuber-
osity, or tubercle, consists of an articular and a
non-articular portion. The articular portion
(fades articularis tuberculi costae), the more in-
ternal and inferior of the two, presents a small,
oval surface for articulation with the extremity
of the transverse process of the lower of the two
vertebrae to which the head is connected. The
non-articular portion is a rough elevation, which
affords attachment to the posterior costo-trans-
verse ligament. The tubercle is much more
prominent in the upper than in the lower ribs.
or shaft.
FIG. 117. — Ribs and articulations of the vertebrae. (Sappey.)
Anterior Extremity. — The anterior or ster-
nal extremity is flattened, and presents a porous,
oval, concave depression, into which the costal
cartilage is received.
The Shaft (corpus costae). — The shaft is thin
and flat, so as to present two surfaces, an ex-
FIG. lie.— A central rib of right side, ternal and an internal, and two borders, a
superior and an inferior.
Surfaces. — The external surface is convex, smooth and marked at its back part, a
little in front of the tuberosity, by a prominent line, directed obliquely from above
PECULIAR RIBS
163
downward and outward; this gives attachment to a tendon of the Ilio-costalis
muscle or of one of its accessory portions, and is called the angle (angulus costce).
At this point the rib is bent in two directions. If the rib is laid upon its lower
border, it will be seen that the portion of the shaft in front of the angle rests upon
this border, while the portion of the shaft behind the angle is bent inward and at
the same time tilted upward. The interval between the angle and the tuberosity
increases gradually from the second to the tenth rib. The portion of bone between
these two parts is rounded, rough, and irregular, and serves for the attachment of
the Longissimus dorsi muscle. The portion of bone between the tubercle and
sternal extremity is also slightly twisted upon its own axis, the external surface
looking downward behind the angle, a little upward in front of it. This surface
jresents, toward its sternal extremity, an oblique line, the anterior angle. The
internal surface is concave, smooth, directed a little upward behind the angle, a
little downward in front of it. This surface is marked by a ridge which corn-
Facet for body of upper dorsal vertebra.
Ridge for interarticular ligament.
Facet for body of lower dorsal vertebra.
Articular part of tuberosity.
Non-articular part of tuberosity.
FIG. 118. — Vertebral extremity of a rib. External surface.
mences at the lower extremity of the head; it is strongly marked as far as the
inner side of the angle, and gradually becomes lost at the junction of the anterior
with the middle third of the bone. The interval between it and the inferior border
presents a groove, subcostal groove (sulcus costce), for the intercostal vessels and
nerve. At the back part of the bone this groove belongs to the inferior border,
but just in front of the angle, where it is deepest and broadest, it corresponds to
the internal surface. The superior edge of the groove is rounded; it serves for
the attachment of the Internal intercostal muscle. The inferior edge corresponds
to the lower margin of the rib and gives attachment to the External intercostal
muscle. Within the groove are seen the orifices of numerous small foramina
which traverse the wall of the shaft obliquely from before backward.
Borders. — The superior border, thick and rounded, is marked by an external
md an internal lip, more distinct behind than in front; they serve for the attach-
lent of the External and Internal intercostal muscles. The inferior border, thin
md sharp, has attached to it the External intercostal muscle.
Peculiar Ribs.
The ribs which require especial consideration are five in number — viz., the
first, second, tenth, eleventh, and twelfth.
First Rib. — The first rib (Fig. 119) is the shortest and the most curved of
ill the ribs; it is broad and flat, its surface looking upward and downward, and
its borders inward and outward. The head is of small size, rounded, and presents
only a single articular facet for articulation with the body of the first thoracic ver-
tebra. The neck is narrow and rounded. The tuberosity, thick and prominent,
rests on the outer border. There is no angle, but in this situation the rib is slightly
bent, with the convexity of the bend upward, so that the head of the bone is
lirected downward. The upper surface of the shaft is marked by two shallow
164
THE SKELETON
depressions, separated by a small rough surface (tuberculum scaleni) for the
attachment of the Scalenus anticus muscle — the shallow groove in front of it
transmitting the subclavian vein, the deeper groove behind it (sulcus subclaviae)
the subclavian artery. Between the groove for the subclavian artery and
the tuberosity is a rough surface, for the attachment of the Scalenus medius
muscle. The under surface is smooth, and destitute of the groove observed on the
other ribs. The outer border is convex, thick, and rounded, and at its posterior
Angle
slightly marked
and close to
tuberosity.
Single articular facet.—
Single articular facet
Single articular facet.
FIGS. 119-123.— Peculiar ribs.
part gives attachment to the first serration of the Serratus inagnus; the inner is
concave, thin, and sharp, and marked about its centre by the commencement of
the rough surface for the Scalenus anticus. The anterior extremity is larger and
thicker than any of the other ribs.
Second Rib. — The second rib (Fig. 120) is much longer than the first, but bears
a very considerable resemblance to it in the direction of its curvature. The non-
articular portion of the tuberosity is occasionally only slightly marked. The angle
THE COSTAL CARTILAGES 165
is slight and situated close to the tuberosity, and the shaft is not twisted, so that
both ends touch any plane surface upon which it may be laid; but there is a similar
though slighter bend, with its convexity upward, to that found in the first rib. The
shaft is not horizontal, like that of the first rib, its outer surface, which is convex,
looking upward and a little outward. It presents, near the middle, a rough emi-
nence, tuberositas costae II, for the attachment of the second and third digitations
of the Serratus magnus; behind and above which is attached the Scalenus
posticus. The inner surface, smooth and concave, is directed downward and a
little inward; it presents a short groove toward its posterior part.
Tenth Rib. — The tenth rib (Fig. 121) has only a single articular facet on its head.
Eleventh and Twelfth Ribs.— The eleventh and twelfth ribs (Figs. 122 and
123) have each a single articular facet on the head, which is of rather large size;
they have no neck or tuberosity, and are pointed at the extremity. The eleventh
has a slight angle and a shallow groove on the lower border. The twelfth has
neither, and is much shorter than the eleventh, and the head has a slight inclina-
tion downward. Sometimes the twelfth rib is even shorter than the first.
Structure. — The ribs consist of cancellous tissue enclosed in a thin, compact
layer.
Development. — Each rib, with the exception of the last two, is developed by
three centres : one for the shaft, one for the head, and one for the tubercle. The
last two have only two centres, that for the tubercle being wanting. Ossification
commences in the shaft of the ribs at a very early period, before its appearance in
the vertebrae. The epiphysis of the head, which is of slightly angular shape, and
that for the tubercle, of a lenticular form, make their appearance between the six-
teenth and twentieth years, and are not united to the rest of the bone until about
the twenty-fifth year.
Attachment of Muscles. — To nineteen : The Internal and External intercostals,
Scalenus anticus, Scalenus medius, Scalenus posticus, Pectoralis minor, Serratus
magnus, Obliquus externus, Quadratus lumborum, Diaphragm, Latissimus dorsi,
Serratus posticus superior, Serratus posticus inferior, Ilio-costalis, Musculus acces-
sorius ad ilio-costalem, Longissimus dorsi, Cervicalis ascendens, Levatores costa-
rum, and Infracostales.
The Costal Cartilages.
The costal cartilage (cartilago costalis) (Fig. 1 10) is white, hyaline cartilage. The
cartilages serve to prolong the ribs forward to the front of the chest, and they
contribute very materially to the elasticity of its walls. The first seven are con-
lected with the sternum, the next three with the lower border of the cartilage of
the preceding rib. The cartilages of the last two ribs have pointed extremities,
which terminate in free ends in the walls of the abdomen. Like the ribs, the
costal cartilages vary in their length, breadth, and direction. They increase in
length from the first to the seventh, then gradually diminish to the last. They
diminish in breadth, as well as the intervals between them, from the first to the
last. They are broad at their attachment to the ribs, and taper toward their sternal
extremities, excepting the first two, which are of the same breadth throughout,
and the sixth, seventh, and eighth, which are enlarged where their margins are
in contact. In direction they also vary : the first descends a little, the second is
horizontal, the third ascends slightly, while all the rest follow the course of the
ribs for a short extent, and then ascend to the sternum or preceding cartilage.
Each costal cartilage presents two surfaces, two borders, and two extremities.
Surfaces. — The anterior surface is convex, and looks forward and upward: that
of the first gives attachment to the costo-clavicular ligament and the Subclavius
muscle; that of the second, third, fourth, fifth, and sixth, at their sternal ends,
166 THE SKELETON
to the Pectoralis major.1 The others are covered by, and give partial attachment
to, some of the great flat muscles of the abdomen. The posterior surface is con-
cave, and directed backward and downward, the first giving attachment to the
Sterno-thyroid, the third to the sixth inclusive to the Triangularis sterni, and
the six or seven inferior ones to the Transversalis muscle and the Diaphragm.
Borders. — Of the two borders, the superior border is concave, the inferior con-
vex; they afford attachment to the internal Intercostal muscles, the upper border
of the sixth giving attachment to the Pectoralis major muscle. The contiguous
borders of the sixth, seventh, and eighth, and sometimes the ninth and tenth,
costal cartilages present small, smooth, oblong-shaped facets at the points where
they articulate.
Extremities. — Of the two extremities, the outer extremity is continuous with the
osseous tissue of the rib to which it belongs. The inner extremity of the first is
continuous with the sternum; the six succeeding ones have rounded extremities,
which are received into shallow concavities on the lateral margins of the sternum.
The inner extremities of the eighth, ninth, and tenth costal cartilages are pointed,
and are connected with the cartilage above. Those of the eleventh and twelfth
are free and pointed.
The costal cartilages are most elastic in youth, those of the false ribs being
more so than the true. In old age they become of a deep yellow color, and are
prone to calcify.
Attachment of Muscles. — To nine: the Subclavius, Sterno-thyroid, Pectoralis
major, Internal oblique, Transversalis, Rectus, Diaphragm, Triangularis sterni,
and Internal intercostals.
Surface Form. — The bones of the chest are to a very considerable extent covered by mus-
cles, so that in the strongly developed muscular subject they are for the most part concealed.
In the emaciated subject, on the other hand, the ribs, especially in the lower and lateral region,
stand out as prominent ridges with the sunken, intercostal spaces between them.
In the middle line, in front, the superficial surface of the sternum is to be felt throughout
its entire length, at the bottom of a deep median furrow situated between the two great pectoral
muscles and called the Sternal furrow. These muscles overlap the anterior surface somewhat, so
that the whole of the sternum in its entire width is not subcutaneous; and this overlapping is
greater opposite the centre of the bone than above and below, so that the furrow is wider at its
upper and lower parts, but narrower in the middle. The centre of the upper border of the ster-
num is visible, constituting the pre-sternal notch, but the lateral parts of this border are obscured
by the tendinous origins of the Sterno-mastoid muscles, which present themselves as oblique
tendinous cords, which narrow and deepen the notch. Lower down on the subcutaneous surface
a well-defined transverse ridge, the angle of Ludovic, is always to be felt. This denotes the line
of junction of the manubrium and body of the bone, and is a useful guide to the second costal
cartilage, and thus to the identity of any given rib. The second rib being found through its
costal cartilage, it is easy to count downward and find any other. From the middle of the
sternum the furrow spreads out, and, exposing more of the surface of the body of the bone,
terminates below in a sudden depression, the infrasternal depression or pit of the stomach
(scrobiculus cordis), which corresponds to the ensiform cartilage. This depression lies between
the cartilages of the seventh ribs, and in it the ensiform cartilage may be felt. The sternum in
its vertical diameter presents a general convexity forward, the most prominent point of which
is at the joint between the manubrium and gladiolus.
On each side of the sternum the costal cartilages and ribs on the front of the chest are par-
tially obscured by the great pectoral muscles; through which, however, they are to be felt as
ridges, with yielding intervals between them, corresponding to the intercostal spaces. Of these
spaces, the one between the second and third ribs is the widest, the next two somewhat nar-
rower, and the remainder, with the exception of the last two, comparatively narrow.
The lower border of the Pectoralis major muscle corresponds to the fifth rib, and below
this, on the front of the chest, the broad, flat outline of the ribs, as they begin to ascend, and
the more rounded outline of the costal cartilages, are often visible. The lower boundary of
the front of the thorax, the abdomino-thoracic arch, which is most plainly seen by arching the
body backward, is formed by the ensiform cartilage and the cartilages of the seventh, eighth,
ninth, and tenth ribs, and the extremities of the eleventh and twelfth ribs or their cartilages.
1 The first and seventh also, occasionally, give origin to the same muscle. — ED. of 15th English Edition.
SURGICAL ANATOMY OF THORAX 167
On each side of the chest, from the axilla downward, the flattened external surfaces of the
ribs may be defined in the form of oblique ridges, separated by depressions corresponding to the
intercostal spaces. They are, however, covered by muscles, which obscure their outline to a
certain extent in the strongly developed. Nevertheless, the ribs, with the exception of the first,
can generally be followed over the front and sides of the chest without difficulty. The first rib,
being almost completely covered by the clavicle and scapula, can only be distinguished in a
small portion of its extent. At the back the angles of the ribs form a slightly-marked oblique
line on each side of and some distance from the vertebral spines. This line diverges some-
what as it descends, and external to it is a broad, convex surface caused by the projection of
the ribs beyond their angles. Over this surface, except where covered by the scapula, the
individual ribs can be distinguished.
Surgical Anatomy. — Malformations of the sternum present nothing of surgical importance
beyond the fact that abscesses of the mediastinum may sometimes escape through the sternal
foramen. Fractures of the sternum are by no means common, owing, no doubt, to the elasticity
of the ribs and their cartilages, which support it like so many springs. When broken it is fre-
quently associated with fracture of the spine, and may be caused by forcibly bending the body
either backward or forward until the chin becomes impacted against the top of the sternum. It
may also be fractured by direct violence or by muscular action. The fracture usually occurs in
the upper half of the body of the bone. Dislocation of the gladiolus from the manubrium also
takes place, and is sometimes described as a fracture.
The bone, cancellous in structure and being subcutaneous, is frequently the seat of gummatous
tumors, and not uncommonly is affected with caries. Occasionally the bone, and especially
its ensiform appendix, becomes altered in shape and driven inward by the pressure, in work-
men, of tools against the chest.
The ribs are frequently broken, though from their connections and shape they are able to
withstand great force, yielding under the injury and recovering themselves like a spring. The
middle of the series are the ones most liable to fracture. The first, and to a less extent the
second, being protected by the clavicle, are rarely fractured; and the eleventh and twelfth, on
account of their loose and floating condition, enjoy a like immunity. The fracture generally
occurs from indirect violence, from forcible compression of the chest-wall, and the bone then
gives way at its weakest part — i. e., just in front of the angle. But the ribs may also be broken
by direct violence, when the bone gives away and is driven inward at the point struck, or they
may be broken by muscular action. It seems probable, however, that in the latter case the
bone has undergone some atrophic changes. Fracture of the ribs is frequently complicated with
some injury to the viscera contained within the thorax or upper part of the abdominal cavity,
and this is most likely to occur in fractures from direct violence. Occasionally supernumerary ribs
exist. They may come from the lumbar vertebrae or from the cervical vertebrae. A lumbar rib
does not cause discomfort.1 A cervical rib is due to freedom of the costal element of the seventh
cervical vertebra.2 In nearly two-thirds of the reported cases the condition is double. It rarely
produces symptoms until after the twentieth year. The symptoms are a superficial pulsation of
the subclavian artery, a prominence which can be felt, and evidences of pressure in the brachial
plexus (Carl Beck). Beck divides the different types of the condition as follows: "(a) Slight
degree: The cervical rib reaches beyond the transverse process, (b) More advanced: The cervical
rib reaches beyond the transverse process, either with a free end or touching the first rib. (c)
Almost complete: The connection between the cartilage of the first rib is formed either by means
of a distinct band or by the end of its long body, (d) Complete: It has become a true rib and
possesses a true cartilage which unites with the cartilage of the first rib."3 A very rare condition
is a rib from the sixth cervical vertebra. The diagnosis is confirmed by the ar-rays. The treatment
of cervical rib is excision.
Fracture of the costal cartilages may also take place, though it is a comparatively rare injury.
The thorax is frequently found to be altered in shape in certain diseases.
The shape of the rickety thorax is produced chiefly by atmospheric pressure. The balance
between the air on the inside of the chest and the outside during some stage of respiration is not
equal, the preponderance being in favor of the air outside; and this, acting on the softened ribs,
causes them to be forced in at the junction of the cartilages with the bones, which is the weakest
part. In consequence of this the sternum projects forward, with a deep depression on either side
caused by the sinking in of the softened ribs. The depression is less on the left side, on account
of the ribs being supported by the heart. The condition is known as pigeon-breast. The
lower ribs, however, are not involved in this deformity, as they are prevented from falling in by
the presence of the stomach, liver, and spleen. And when the liver and spleen, are enlarged,
as they sometimes are in rickets, the lower ribs may be pushed outward: this causes a trans-
verse constriction just above the costal arch. The anterior extremities of the ribs are usually
enlarged in rickets, giving rise to what has been termed the rickety rosary. The phthisical
i Carl Beck, in Jour. Amer. Med. Assoc., June 17, 1905.
1 Piersol's Human Anatomy, p. 155.
3 Jour. Amer. Med. Aaeoc., June 17, 1905.
168 THE SKELETON
chest is often long and narrow, flattened from before backward, and with great obliquity of the
ribs and projection of the scapulae. In pulmonary emphysema the chest is enlarged in all its
diameters, and presents on section an almost circular outline. It has received the name of the
barrel-shaped chest. In severe cases of lateral curvature of the spine the thorax becomes
much distorted. In consequence of the rotation of the bodies of the vertebrae which takes
place in this disease the ribs opposite the convexity of the thoracic curve become extremely con-
vex behind, being thrown out and bulging, and at the same time flattened in front, so that the
two ends of the same rib are almost parallel. Coincident with this, the ribs on the opposite
side, on the concavity of the curve, are sunk and depressed behind and bulging and convex in
front. In addition to this the ribs become occasionally welded together by bony material.
The ribs are frequently the seat of caries leading to abscesses and sinuses, which may
burrow to a considerable extent over the wall of the chest. The only special anatomical point
in connection with abscesses and sinuses is that care must be taken in dealing with them that
the intercostal space is not punctured and the pleural cavity opened or the intercostal vessels
wounded, as the necrosed portion of bone is generally situated on the internal surface of the rib.
In cases of empyema the chest requires opening t-» evacuate the pus. There is consider-
able difference of opinion as to the best position to do this. Probably the best place for inter-
costal drainage is between the fifth and sixth ribs, in or a little in front of the mid-axillary line.
This is the last part of the cavity to be closed by the expansion of the lung; it is not thickly
covered by soft parts; the space between the two ribs is sufficiently great to allow of the intro-
duction of a fair-sized drainage-tube, and when the patient is confined to bed he does not lie
upon the drainage-tube as he does when the opening is posterior. Better than intercostal drain-
age in the vast majority of cases is rib resection and drainage. A portion of the fifth or sixth
rib should be removed in the mid-axillary line. In chronic empyema the lung becomes shrunken
and adherent and simple drainage will not bring about a cure. It is necessary in such cases
to do an operation that will permit of collapse of the chest wall. Esllander's operation consists
in resecting a portion of every rib which overlies the cavity of the empyema. Schede's opera-
tion consists in removing ribs from the second rib down over the empyema cavity. The ribs
are removed from cartilages to angles, and intercostal muscles and the parietal layer of the
pleura are also taken away. Fowler and de Lorme not only practice extensive rib resection
and remove the parietal layer of the pleura, but also remove the pulmonary pleura (total pleu-
rectomy or pulmonary decortication).
THE EXTREMITIES.
The extremities, or limbs, are those long, jointed appendages of the body
which are connected with the trunk by one end and free in the rest of their extent.
They are jour in number: an upper or thoracic pair, connected with the thorax
through the intervention of the shoulder, and subservient mainly to prehension;
and a lower pair, connected with the pelvis, intended for support and locomotion.
Both pairs of limbs are constructed after one common type, so that they present
numerous analogies, while at the same time certain differences are observed
between the upper and lower pair, dependent on the peculiar offices they have
to perform.
The bones by which the upper and lower limbs are attached to the trunk are
named respectively the shoulder and pelvic girdles, and they are constructed on the
same general type, though presenting certain modifications relating to the different
uses to which the upper and lower limbs are respectively applied. The shoulder
girdle is formed by the scapulae and clavicles, and is imperfect in front and behind.
In front, however, the girdle is completed by the upper end of the sternum, with
which the inner extremities of the clavicle articulate. Behind, the girdle is widely
imperfect and the scapula is connected to the trunk by muscles only. The pelvic
girdle is formed by the innominate bones, and is completed in front through the
symphysis pubis, at which the two innominate bones articulate with each other.
It is imperfect behind, but the intervening gap is filled in by the upper part of
the sacrum. The pelvic girdle, therefore, presents, with the sacrum, a complete
ring, comparatively fixed, and presenting an arched form which confers upon it a
solidity manifestly intended for the support of the trunk, and in marked contrast
to the lightness and mobility of the shoulder girdle.
THE CLAVICLE 169
With regard to the morphology of these girdles, the blade of the scapula is
gnu-rally believed to correspond to the ilium; but with regard to the clavicles
there is some difference of opinion: formerly it was believed that they corre-
sponded to the ossa pubis, meeting at the syrnphysis, but it is now generally
taught that trie clavicle has no homologue in the pelvic girdle, and that the os
pubis and ischium are represented by the small coracoid process in man and
most mammals.
THE UPPER EXTREMITY.
The bones of the upper extremity consist of those of the shoulder girdle, of the
arm, the forearm, and the hand.
THE SHOULDER GIRDLE.
The shoulder girdle consists of the clavicle and the scapula.
The Clavicle or Collar Bone (Clavicula).
The clavicle or key bone (clavis, a key) obtains it name from its supposed
resemblance to the key used by the Romans. It forms the anterior portion of the
shoukler girdle. It is a long bone, curved somewhat like the italic letter /, and
placed nearly horizontally at the upper and anterior part of the thorax, imme-
diately above the first rib. It articulates by its inner extremity with the upper
border of the sternum, and by its outer extremity with the acromion process of the
scapula, serving to sustain the upper extremity in the various positions which it
assumes, whilst at the same time it allows of great latitude of motion in the arm.1
It presents a double curvature when looked at in front, the convexity being for-
ward at the sternal end and the concavity at the scapular end. Its outer third is
flattened from above downward, and extends, in the natural position of the bone,
from a point opposite the coracoid process to the acromion. Its inner two-thirds
are of a prismatic form, and extend from the sternum to a point opposite the cora-
coid process of the scapula.
Outer, External, or Flattened Portion. — The outer third is flattened from above
downward, so as to present two surfaces, an upper and a lower; and two borders,
an anterior and a posterior.
Surfaces. — The upper surface is flattened, rough, marked by impressions for the
attachment of the Deltoid in front and the Trapezius behind; between these two
impressions, externally, a small portion of the bone is subcutaneous. The under
surface is flattened. At its posterior border, a little external to the point where the
prismatic joins with the flattened portion, is a rough eminence, the conoid tubercle
(tuberositas coracoidea) ; this, in the natural position of the bone, surmounts the
coracoid process of the scapula and gives attachments to the conoid ligament.
From this tubercle an oblique line, occasionally a depression, passes forward
and outward to near the outer end of the anterior border; it is called the oblique
line or trapezoid ridge, and affords attachment to the trapezoid ligament.
Borders. — The anterior border is concave, thin, and rough, and gives attachment
to the Deltoid; it occasionally presents, at its inner end, at the commencement of
the deltoid impression, a tubercle, the deltoid tubercle, which is sometimes to be
felt in the living subject. The posterior border is convex, rough, broader than the
anterior, and gives attachment to the Trapezius.
i The clavicle acts especially as a fulcrum to enable the muscles to give lateral motion to the arm. It is
accordingly absent in those animals whose fore limbs are used only for progression, but is present for the most
part in those animals whose anterior extremities are clawed and used for prehension, though in some of them —
as, for instance, in a large number of the carnivora — it is merely a rudimentary bone suspended among the
muscles, and not articulating with the scapula or sternum. — ED. of 15th English Edition.
170 THE SKELETON
Inner, Internal, or Prismatic Portion. — The prismatic portion forms the inner
two-thirds of the bone. It is curved so as to be convex in front, concave behind,
and is marked by three borders, separating three surfaces.
Borders. — The anterior border is continuous with the anterior margin of the flat
portion. At its commencement it is smooth, and corresponds to the interval
between the attachment of the Pectoralis major and Deltoid muscles; at the inner
half of the clavicle it forms the lower boundary of an elliptical space for the
attachment of the clavicular portion of the Pectoralis major, and approaches the
posterior border of the bone. The superior border is continuous with the posterior
margin of the flat portion, and separates the anterior from the posterior surface.
At its commencement it is smooth and rounded, becomes rough toward the inner
third for the attachment of the Sterno-mastoid muscle, and terminates at the
upper angle of the sternal extremity. The posterior or subclavian border separates
the posterior from the inferior surface, and extends from the conoid tubercle to
the rhomboid impression. It forms the posterior boundary of the groove for the
Subclavius muscle, and gives attachment to a layer of cervical fascia covering
the Omo-hyoid muscle.
Surfaces. — The anterior surface is included between the superior and anterior
borders. It is directed forward and a little upward at the sternal end, outward
and still more upward at the acromial extremity, where it becomes continuous
with the upper surface of the flat portion. Externally, it is smooth, convex,
nearly subcutaneous, being covered only by the Platysma; but, corresponding
to the inner half of the bone, it is divided by a more or less prominent line into
two parts: a lower portion, elliptical in form, rough, and slightly convex, for the
attachment of the Pectoralis major; and an upper part, which is rough, for the
attachment of the Sterno-cleido-mastoid. Between the two muscular impressions
is a small subcutaneous interval. The posterior or cervical surface is smooth,
flat, and looks backward toward the root of the neck. It is limited, above, by the
superior border; below, by the subclavian border; internally, by the margin of the
sternal extremity; externally, it is continuous with the posterior border of the flat
portion. It is concave from within outward, and is in relation, by its lower part,
with the suprascapular vessels. This surface, at about the junction of the inner
and outer curves, is also in close relation with the brachial plexus and subclavian
vessels. It gives attachment, near the sternal extremity, to part of the Sterno-hyoid
muscle; and presents, at or near the middle, a foramen, nutrient foramen (foramen
nutricium). It opens into a canal, nutrient canal (canalis nutricius), which is
directed obliquely outward and transmits the chief nutrient artery of the bone.
Sometimes there are two foramina on the posterior surface, or one on the
posterior, and one on the inferior surface. The inferior or subclavian surface
is bounded, in front, by the anterior border; behind, by the subclavian border.
It is narrow internally, but gradually increases in width externally, and is
continuous with the under surface of the flat portion. Commencing at the
sternal extremity may be seen a small facet, the costal facet, for articulation
with the cartilage of the first rib. This is continuous with the articular surface
at the sternal end of the bone. External to this is a broad, rough surface, the
rhomboid impression (tuberositas costalis), rather more than an inch in length, for
the attachment of the costo-clavicular (rhomboid) ligament. The remaining part
of this surface is occupied by a longitudinal groove, the subclavian groove, broad
and smooth externally, narrow and more uneven internally; it gives attachment to
the Subclavius muscle, and by its margins to the costo-coracoid membrane,
which splits to enclose the muscle. Not infrequently this groove is subdivided
into two parts by a longitudinal line, which gives attachment to the intermuscular
septum of the Subclavius muscle.
THE CLAVICLE
171
Internal or Sternal Extremity (extremitas sternalis). — The internal or sternal
extremity of the clavicle is triangular in form, directed inward and a little down-
ward and forward; and presents an articular facet (fades articularis sternalis),
concave from before backward, convex from above downward, which articulates
with the sternum through the intervention of an interarticular fibro-cartilage;
the circumference of the articular surface is rough, for the attachment of
numerous ligaments. The posterior border of this surface is prolonged back-
ward, so as to increase the size of the articular facet; the upper border gives
attachment to the interarticular fibro-cartilage, and the lower border is con-
tinuous with the costal facet on the inner end of the inferior or subclavian sur-
face, which articulates with the cartilage of the first rib.
Outer or Acromial Extremity (extremitas acromialis) . — The outer or acromial
extremity, directed outward and forward, presents a small, flattened, oval facet,
Acromial extremity.
Sternal extremity.
FIG. 124. — Left clavicle. Superior surface.
FIG. 125.— Left clavicle. Inferior surface.
acromial surface (fades articularis acromialis) , which looks obliquely downward,
for articulation with the acromion process of the scapula. The circumference
of the articular facet is rough, especially above, for the attachment of the
acromio-clavicular ligaments.
Peculiarities of the Bone in the Sexes and in Individuals.— In the female the
clavicle is generally shorter, thinner, less curved, and smoother than in the male.
In those persons who perform considerable manual labor, which brings into con-
stant action the muscles connected with this bone, it becomes thicker and more
curved, its ridges for muscular attachment become prominently marked. The
right clavicle is generally longer, thicker, and rougher than the left.
Structure. — The shaft, as well as the extremities, consists of cancellous tissue,
invested in a compact layer much thicker in the middle than at either end. The
clavicle is highly elastic, by reason of its curves. From the experiments of Mr.
Ward it has been shown that it possesses sufficient longitudinal elastic force to
project its own weight nearly two feet on a level surface when a smart blow is
struck on it; and sufficient transverse elastic force, opposite the centre of its
172 THE SKELETON
anterior convexity, to throw its own weight about a foot. This extent of elastic
power must serve to moderate very considerably the effect of concussions received
upon the point of the shoulder.
Development.— By two centres: one for the shaft and outer extremity and
one for the sternal extremity. The centre for the shaft appears very early,
before any other bone — according to Beclard, as early as the thirtieth day.
The centre for the sternal end makes its appearance about the eighteenth or
twentieth year, and unites with the rest of the bone about the twenty-fifth year.
Articulations. — With the sternum, scapula, and cartilage of the first rib.
Attachment of Muscles. — To six : the Sterno-cleido-mastoid, Trapezius,
Pectoralis major, Deltoid, Subclavius, and Sterno-hyoid.
Surface Form. — The clavicle can be felt throughout its entire length, even in persons who
are very fat. Commencing at the inner end, the enlarged sternal extremity, where the bone
projects above the upper margin of the sternum, can be felt, forming with the sternum and the
rounded tendon of the Sterno-mastoid a V-shaped notch, the pre-sternal notch. Passing out-
ward, the shaft of the bone can be felt immediately under the skin, with its convexity forward
in the inner two-thirds, the surface partially obscured above and below by the attachments of
the Sterno-mastoid and Pectoralis major muscles. In the outer third it forms a gentle curve
backward, and terminates at the outer end in a somewhat enlarged extremity which articulates
with the acromial process of the scapula. The direction of the clavicle is almost, if not quite,
horizontal when the arm is lying quietly by the side, though in well-developed subjects it may
incline a little upward at its outer end. Its direction is, however, very changeable, altering
with the varying movements of the shoulder-joint.
Surgical Anatomy. — The clavicle is the most frequently fractured of any single bone in the
body. This is due to the fact that it is much exposed to violence, and is the only bony connec-
tion between the upper limb and the trunk. The bone, moreover, is slender, and is very super-
ficial. The bone may be broken by direct or indirect violence or by muscular action. The most
common cause is, however, from indirect violence, and the bone then gives way at the junction
of the fixed outer one-third with the movable inner two-thirds of the bone. This is the weakest
and most slender part of the bone. The fracture is generally oblique, and the displacement
of the outer fragments is inward, away from the surface of the body; hence compound
fracture of the clavicle is of rare occurrence. The inner fragment as a rule is little displaced
(page 505). Beneath the bone the main vessels of the upper limb and the great nerve-cords of
the brachial plexus lie on the first rib, and are liable to be wounded in fracture, especially in
fracture from direct violence, when the force of the blow drives the broken ends inward. For-
tunately, the Subclavius muscle is interposed between these structures and the clavicle, and
this often protects them from injury.
The clavicle is not uncommonly the seat of sarcomatous tumors, rendering the operation
of excision of the entire bone necessary. This operation is best performed by exposing the
bone freely, disarticulating at the acromial end, and turning it inward. The removal of
the outer part is comparatively easy, but resection of the inner part is fraught with difficulty, the
main danger being the risk of wounding the great veins which are in relation with its under
surface.
The Scapula or Shoulder Blade.
The scapula (axaxdvr] , a spade), or blade bone, forms the back part of
the shoulder girdle. It is a large, flat bone, triangular in shape, situated at
the posterior aspect and side of the thorax, between the second and seventh, or
sometimes the eighth, ribs, its internal border or base being about an inch from
and nearly but not quite parallel with the spinous processes of the vertebrae, so
that it is rather closer to them above than below. It presents for examination-
two surfaces, three borders, and three angles.
Surfaces. Anterior or Costal Surface, Ventral Aspect or Venter (fades costalis). —
The anterior surface (Fig. 126) presents a broad concavity, the subscapular
fossa (fossa subscapularis) . It is 'marked, in the inner two-thirds, by several
oblique ridges (linecB musculares) , which pass from behind outward and upward ;
the outer third is smooth. The oblique ridges give attachment to the tendinous
intersections, and the surfaces between them to the fleshy fibres, of the Sub-
scapularis muscle. The anterior third of the fossa, which is smooth, is covered
THE SCAPULA
173
by, but does not afford attachment to, the fibres of this muscle. The venter is
separated from the internal border by a smooth, triangular margin at the supe-
rior and inferior angles/and in the interval between these by a narrow edge which
is often deficient. This marginal surface affords attachment throughout its entire
extent to the Serratus magnus muscle. The subscapular fossa presents a trans-
verse depression at its upper part, where the bone appears to be bent on itself,
forming a considerable angle, called the subscapular angle (angulus subscapularis) ,
thus giving greater strength to the body of the bone from its arched form, whilst
the summit of the arch serves to support the spine and acromion process. It is in
FIG. 126. — Left scapula. Anterior surface or venter.
this situation that the fossa is deepest, so that the thickest part of the Subscapu-
laris muscle lies in a line perpendicular to the plane of the glenoid cavity, and.
must consequently operate most effectively on the head of the humerus, which
is contained in that cavity. The portion of bone between the suprascapular
notch and the infraglenoid tubercle is sometimes called the surgical neck.
Posterior or Dorsal Surface or Dorsum (fades dorsalis). — The posterior or dorsal
surface (Fig. 127) is arched from above downward, alternately concave and
174
THE SKELETON
convex from side to side. It is subdivided unequally into two parts by the
spine ; the portion above the spine is called the supraspinous fossa, and that below
it the infraspinous fossa.
The supraspinous fossa (fossa supraspinata) , the smaller of the two, is concave,
smooth, and broader at the vertebral than at the humeral extremity. It affords
attachment by its inner two-thirds to the Supraspinatus muscle.
Cor a co
Groove for Dorsalis
Scapulx Artery
Inferior
FIG. 127. — Left scapula. Posterior surface or dorsum.
The infraspinous fossa (fossa infraspinata) is much larger than the preceding;
toward its vertebral margin a shallow concavity is seen at its upper part ; its centre
presents a prominent convexity, whilst toward the axillary border is a deep groove
which runs from the upper toward the lower part. The inner two-thirds of this
surface affords attachment to the Infraspinatus muscle; the outer third is only cov-
ered by it, without giving origin to its fibres. This surface is separated from the
axillary border by an elevated ridge, which runs from the lower margin of the glenoid
cavity downward and backward to the posterior border, about an inch above the in-
THE SCAPULA 175
ferior angle. The ridge serves for the attachment of a strong aponeurosis which
separates the Inf raspinatus from the two Teres muscles. The surface of bone between
this line and the axillary border is narrow in the upper two-thirds of its extent,
and traversed near its centre by a groove for the passage of the dorsalis scapulae
vessels; it affords attachment to the Teres minor muscle. Its lower third presents a
broader, somewhat triangular surface, which gives origin to the Teres major, and
over which the Latissimus dorsi glides; sometimes the latter muscle takes origin
by a few fibres from this part. The broad and narrow portions of bone above
alluded to are separated by an oblique line which runs from the axillary border,
downward and backward, to meet the elevated ridge: to it is attached the
aponeurosis separating the two Teres muscles from each other.
The spine (spina scapula?) is a prominent plate of bone which crosses obliquely
the inner four-fifths of the dorsum of the scapula at its upper part, and separates the
supra- from the infraspinous fossa : it commences at the vertebral border by a smooth,
triangular surface, over which the Trapezius glides, separated from the bone by a
bursa, and, gradually becoming more elevated as it passes outward, terminates in
the acromion process, which overhangs the shoulder-joint. The spine is triangular
and flattened from above downward, its apex corresponding to the vertebral
border, its base (which is directed outward) to the neck of the scapula. It pre-
sents two surfaces and three borders. Its superior surface is concave, assists
in forming the supraspinous fossa, and affords attachment to part of the Supra-
spinatus muscle. Its inferior surface forms part of the infraspinous fossa, gives
origin to part of the Infraspinatus muscle, and presents near its centre the orifice
of a nutrient canal. Of the three borders, the anterior is attached to the dorsum
of the bone; the posterior, or crest of the spine, is broad, and presents two lips
and an intervening rough interval. To the superior lip is attached the Trapezius
to the extent shown in the figure. A rough tubercle is generally seen occupying
that portion of the spine which receives the insertion of the middle and inferior
fibres of this muscle. To the inferior lip, throughout its whole length, is attached
the Deltoid. The intervals between the lips is also partly covered by the tendinous
fibres of these muscles. The external border, or base, the shortest of the three, is
slightly concave, its edge thick and round, continuous above with the under sur-
face of the acromion process, below with the neck of the scapula. The narrow
portion of bone external to this border, and separating it from the glenoid cavity,
is called the great scapular notch, and serves to connect the supra- and infraspinous
fossae.
The acromion process (acromion), so called from forming the summit of the
shoulder (dxpov, a summit; dtpo^, the shoulder), is a large and somewhat triangular
or oblong process, flattened from behind forward, directed at first a little outward,
and then curving forward and upward, so as to overhang the glenoid cavity. Its
upper surface, directed upward, backward, and outward, is convex, rough, and
gives attachment to some fibres of the Deltoid, and in the rest of its extent it is
subcutaneous. Its under surface is smooth and concave. Its outer border is thick
and irregular, and presents three or four tubercles for the tendinous origins of the
Deltoid muscle. Its inner margin, shorter than the outer, is concave, gives attach-
ment to a portion of the Trapezius muscle, and presents about its centre a small
oval surface for articulation with the acrornial end of the clavicle. Its apex, which
corresponds to the point of meeting of these two borders in front, is thin, and
has attached to it the coraco-acromial ligament.
Margins or Borders of the Scapula. Superior Border (margo superior) . — Of the
three borders of the scapula, the superior is the shortest and thinnest; it is concave
and extends from the internal angle to the coracoid process. At its outer part is a
deep, semicircular notch, the suprascapular notch (incisura scapulae) , formed partly
by the base of the coracoid process. The notch is converted into a foramen by the
178 THE SKELETON
transverse ligament, and serves for the passage of the suprascapular nerve. Some-
times this foramen is entirely surrounded by bone. The adjacent margin of the
superior border affords attachment to the Omo-hyoid muscle.
External or Axillary Border (mar go axillaris). — The external or axillary border
is the thickest of the three. It commences above at the lower margin of the
glenoid cavity, and inclines obliquely downward and backward to the inferior
angle. Immediately below the glenoid cavity is a rough impression, the infra-
glenoid tubercle (tuberositas infraglenoidalis), about an inch in length, which
affords attachment to the long head of the Triceps muscle; in front of this is
a longitudinal groove, which extends as far as the lower third of the axillary
border and affords origin to part of the Subscapularis muscle. The inferior
third of this border, which is thin and sharp, serves for the attachment of a few
fibres of the Teres major behind and the Subscapularis in front.
Internal or Vertebral Border (margo vertebralis) . — The internal or vertebral bor-
der, also named the base, is the longest of the three, and extends from the internal to
the inferior angle of the bone. It is arched, is intermediate in thickness between the
superior and the external borders, and the portion of it above the spine is bent con-
siderably outward, so as to form an obtuse angle with the lower part. The vertebral
border presents an anterior lip, a posterior lip, and an intermediate space. Theemfe-
rior lip affords attachment to the Serratus magnus ; the posterior lip, to the Supra-
spinatus above the spine, the Infraspinatus below; the interval between the two lips,
to the Levator anguli scapulae above the triangular surface at the commencement
of the spine, the Rhomboideus minor to the edge of that surface; the Rhomboideus
major being attached by means of a fibrous arch connected above to the lower
part of the triangular surface at the base of the spine, and below to the lower part
of the posterior border.
Angles. Internal or Medial Angle (anguine medialis). — Of the three angles, the
internal, formed by the junction of the superior and internal borders, is thin,
smooth, rounded, somewhat inclined outward, and gives attachment to a few
fibres of the Levator anguli scapulae muscle.
Inferior Angle (angulus inferior}. — The inferior angle, thick and rough, is
formed by the union of the vertebral and axillary borders, its outer surface afford-
ing attachment to the Teres major and frequently to a few fibres of the Latissimus
dorsi.
External or Lateral Angle (angulus lateralis). — The external angle is the thickest
part of the bone, and forms what is called the head of the scapula. The head
presents a shallow, pyriform, articular surface, the glenoid surface or cavity (cav-
itas glenoidalis, from ftyvir}, a socket), whose longest diameter is from above
downward, and its direction outward and forward. It is broader below than
above. Just above it is a rough surface, the supraglenoid tubercle or tuberosity
(tuberositas supraglenoidalis) , to which is attached the long tendon of the Biceps
muscle. The glenoid cavity is covered with cartilage in the recent state; and
its margins are slightly raised and give attachment to a fibre-cartilaginous struc-
ture, the glenoid ligament, by which its cavity is deepened. The anatomical neck
of the scapula (collum scapula) is the slightly depressed surface which surrounds
the head; it is more distinct on the posterior than on the anterior surface, and
below than above. In the latter situation it has arising from it a thick prominence,
the coracoid process.
The coracoid process (processus coracoideus) , so called from its fancied resemblance
to a crow's beak (xopaz, a crow), is a thick, curved process of bone which arises by
a broad base from the upper part of the neck of the scapula; it is directed at first
upward and inward, then, becoming smaller, it changes its direction and passes for-
ward and outward. The ascending portion, flattened from before backward, pre-
sents in front a smooth, concave surface over which passes the Subscapularis
THE SCAPULA
177
muscle. The horizontal portion is flattened from above downward, its upper
surface is convex and irregular, and gives attachment to the Pectoralis minor;
its under surface is smooth; its
inner border is rough, and gives
attachment to the Pectoralis
minor; its outer border is also
rough for the coraco-acromial
ligament, while the apex' is
embraced by the conjoined
tendon of origin of the short
head of the Biceps and of the
Coraco-brachialis and gives at-
tachment to the costo-coracoid
ligament. At the inner side of
the root of the coracoid process
is a rough impression for the
attachment of the conoid liga-
ment; and running from it
obliquely forward and outward
on the upper surface of the
horizontal portion, an elevated
ridge for the attachment of the
trapezoid ligament.
Structure. — In the head, pro-
cesses, and all the thickened
parts of the bone the scapula
is composed of cancellous tis-
sue, while in the rest of its ex-
tent it is composed of a thin
layer of dense, compact tissue.
The centre part of the supra-
spinous fossa and the upper
part of the infraspinous fossa, but especially the former, are usually so thin as to
be semitransparent ; occasionally the bone is found wanting in this situation,
and the adjacent muscles come into contact.
Development (Fig. 128). — By seven or more centres: one for the body, two for
the coracoid process, two for the acromion, one for the vertebral border, and one
for the inferior angle. Ossification of the body of the scapula commences about
the second month of foetal life by the formation of an irregular quadrilateral
plate of bone immediately behind the glenoid cavity. This plate extends itself so
as to form the chief part of the bone, the spine growing up from its posterior,
surface about the third month. At birth a large part of the scapula is osseous,
but the glenoid cavity, coracoid and acromion processes, the posterior border, and
inferior angle are cartilaginous. From the fifteenth to the eighteenth month after
birth ossification takes place in the middle of the coracoid process, which usually
becomes joined with the rest of the bone at the time when the other centres make
their appearance. Between the fourteenth and twentieth years ossification of the
remaining centres takes place in quick succession, and in .the following order:
first, in the root of the coracoid process, in the form of a broad scale; secondly,
near the base of the acromion process; thirdly, in the inferior angle and contigu-
ous part of the posterior border; fourthly, near the extremity of the acromion;
fifthly, in the posterior border. The acromion process, besides being formed of
two separate nuclei, has its base formed by an extension into it of the centre of
ossification which belongs to the spine, the extent of which varies in different
12
&
FIG. 128. — Plan of the development of the scapula. By seven
centres. The epiphyses (except one for the coracoid process)
appear from fifteen to seventeen years, and unite between twenty-
two and twenty-five years of age.
178 THE SKELETON
cases. The two separate nuclei unite and then join with the extension from the
spine. These various epiphyses become joined to the bone between the ages of
twenty-two and twenty-five years. Sometimes failure of union between the
acromion process and spine occurs, the junction being effected by fibrous tissue
or by an imperfect articulation ; in some cases of supposed fracture of the acromion
with ligamentous union it is probable that the detached segment was never united
to the rest of the bone. The upper third of the glenoid cavity is usually ossified
from a separate centre (subcoracoid) which makes its appearance between the
tenth and eleventh years. Very often, in addition, an epiphysis appears for the
lower part of the glenoid cavity.
Articulations. — With the humerus and clavicle.
Attachment of Muscles. — To seventeen: to the anterior surf ace, the Subscapu-
laris; posterior surface, Supraspinatus, Infraspinatus; spine, Trapezius, Deltoid;
superior border, Omo-hyoid; vertebral border, Serratus magnus, Levator anguli
scapulae, Rhomboideus minor and major; axillary border, Triceps, Teres minor,
Teres major; apex of glenoid cavity, long head of the Biceps; coracoid process,
short head of the Biceps, Coraco-brachialis, Pectoralis minor; and to the inferior
angle occasionally a few fibres of the Latissimus dorsi.
Surface Form. — The only parts of the scapula which are truly subcutaneous are the spine
and acromion process, but, in addition to these, the coracoid process, the internal or vertebral
border and inferior angle, and, to a less extent, the axillary border, may be defined. The acro-
mion process and spine of the scapula are easily felt throughout their entire length, forming,
with the clavicle, the arch of the shoulder. The acromion can be ascertained to be connected
to the clavicle at the acromio-clavicular joint by running the finger along it, its position being
often indicated by an irregularity or bony outgrowth from the clavicle close to the joint. The
acromion can be felt forming the point of the shoulder, and from this can be traced backward to
join the spine of the scapula. The place of junction is usually denoted by a prominence, which is
sometimes called the acromial angle. From here the spine of the scapula can be felt as a promi-
nent ridge of bone, marked on the surface as an oblique depression, which becomes less and less
distinct, and terminates a little external to the spinous processes of the vertebrae. Its termination is
usually indicated by a slight dimple in the skin on a level with the interval between the third and
fourth thoracic spines. Below thi? point the vertebral border of the scapula may be traced, run-
ning downward and outward, and thus diverging from the vertebral spines, to the inferior angle
of the bone, which can be recognized, although covered by the Latissimus dorsi muscle. From
this angle the axillary border can usually be traced through this thick muscular covering, form-
ing, with the muscles, the posterior fold of the axilla. The coracoid process may be felt about
an inch below the junction of the middle and outer thirds of the clavicle. Here it is covered by
the anterior border of the deltoid and lies a little to the outer side of a slight depression which
corresponds to the interval between the Pectoralis major and Deltoid muscles. When the arms
are hanging by the side, the upper angle of the scapula corresponds to the upper border of the
second rib or the interval between the first and second thoracic spines, the inferior angle to the
upper border of the eighth rib or the interval between the seventh and eighth thoracic spines.
Surgical Anatomy. — Fractures of the body of the scapula are rare, owing to the mobility of the
bone, the thick layer of muscles by which it is encased on both surfaces, and the elasticity of the
ribs on which it rests. Fracture of the neck of the bone is also uncommon. The most frequent
course of a line of fracture of the neck is from the suprascapular notch to the infraglenoid
tubercle (surgical neck], and it derives its principal interest from its simulation to a subglenoid
dislocation of the humerus. The diagnosis can be made by noting the alteration in the position
of the coracoid process. A fracture of the neck external to, and not including, the coracoid
process (anatomical neck} is said to occur, but it is exceedingly doubtful whether such an
accident ever takes place. The acromion process is more frequently broken than any other
part of the bone, and there is sometimes, in young subjects, a separation of the epiphysis. It
is believed that many of the cases of supposed fracture of the acromion, with fibrous union,
which have been found on post-mortem examination are really cases of imperfectly united
epiphysis. Sir Astley Cooper believed that most fractures of this bone united by fibrous
tissue, and the cause of this mode of union was the difficulty there was in keeping the frac-
tured ends in constant apposition. The coracoid process is occasionally broken off, either from
direct violence or perhaps, rarely, from muscular action.
Tumors of various kinds grow from the scapula. Of the innocent form of tumors probably
the osteomata are the most common. When an osteoma grows from the venter of the scapula, as it
sometimes does, it is of the compact variety, such as usually grows from membrane-formed bones,
THE HUMERUS 179
as the bones of the skull. This would appear to afford evidence that this portion of the bone
is formed from membrane, and not, like the rest of the bone, from cartilage. Sarcomatous
tumors sometimes grow from the scapula, and may necessitate removal of the bone, with or
without amputation of the upper limb. Removal of the upper limb with the scapula and the
outer two-thirds of the clavicle is known as the interscapulo-thoracic amputation. The
scapula may be partially resected or completely excised. There are several methods of com-
plete excision. The bone may be excised by a T-shaped incision, and, the flaps being reflected,
the removal is commenced from the posterior or vertebral border, so that the subscapular
vessels which lie along the axillary border are among the last structures divided, and can be
at once secured.
THE ARM.
The arm is that portion of the upper extremity which is situated between the
shoulder and the elbow. Its skeleton consists of a single bone, the humerus.
The Humerus or Upper Arm Bone (Figs. 129, 130).
The humerus (from humerus, or more correctly umerus, the shoulder) is the
longest and largest bone of the upper extremity; it presents for examination a
shaft and two extremities.
Upper Extremity. — The upper extremity presents a large, rounded head,
joined to the shaft by a constricted portion, called the neck, and two other emi-
nences, the greater and lesser tuberosities.
The Head (caput humeri). — The head, nearly hemispherical in form,1 is directed
upward, inward, and slightly backward, and articulates with the glenoid cavity
of the scapula; its surface is smooth and coated with cartilage in the recent state.
The circumference of its articular surface is slightly constricted, and is termed
the anatomical neck, in contradistinction to the constriction which exists below the
tuberosities. The latter is called the surgical neck (collum chirurgicum) , f rom its
often being the seat of fracture. It should be remembered, however, that frac-
ture of the anatomical neck does sometimes, though rarely, occur.
ANATOMICAL NECK (collum anatomicum). — The anatomical neck is obliquely
directed, forming an obtuse angle with the shaft. It is more distinctly marked in
the lower half of its circumference than in the upper half, where it presents a nar-
row groove, separating the head from the tuberosities. Its circumference affords
attachment to the capsular ligament and is perforated by numerous vascular
foramina.
Greater Tuberosity (tuberculum majus}. — The greater tuberosity is situated on
the outer side of the head and lesser tuberosity. Its upper surface is rounded and
marked by three flat facets, separated by two slight ridges: the highest facet gives
attachment to the tendon of the Supraspinatus; the middle one, to the Infra-
spinatus; the inferior facet and the shaft of the bone below it, to the Teres minor.
The outer surface of the great tuberosity is convex, rough, and continuous with
the outer side of the shaft.
Lesser Tuberosity (tuberculum minus). — The lesser tuberosity is more promi-
nent, although smaller than the greater: it is situated in front of the head, and
is directed inward and forward. Its summit presents a prominent facet for 'the
insertion of the tendon of the Subscapularis muscle. The tuberosities are sepa-
rated from one another by a deep groove, the bicipital groove (sulcus intertuber-
cularis). This groove lodges the long tendon of the Biceps muscle, with which
1 Though the head is nearly hemispherical in form, its margin, as Sir G. Humphry has shown, is by no means
a true circle. Its greatest measurement is from the top of the bicipital groove in a direction downward, inward,
and backward. Hence it follows that the greatest elevation of the arm can be obtained by rolling the articular
surface in this direction — that is to sa^, obliquely upward, outward, and forward. — ED. of 15th English Edition.
180
THE SKELETON
Common origin of
FLEXOR CARPI RADIALIS.
PALMARIS LONGUS.
FLEXOR SUBLIMIS DIGITORUM
FLEXOR CARPI ULNARIS.
SUPINATOR RADII LONQUS.
EXTENSOR CARPI RADIALIS
LONQIOR.
Common origin of
EXTENSOR CARPI RADIALIS BREVIS,
" COMMUNIS DIGITORUM.
" MINIMI DIGITI.
' CARPI ULNARIS.
SUPINATOR BREVIS.
FIG. 129. — Left humerus. Anterior v«w.
THE HUMER US 1 81
runs a branch of the anterior circumflex artery. It commences above between
the two tuberosities, passes obliquely downward and a little inward, and termin-
ates at the junction of the upper with the middle third of the bone. It is deep
and narrow at the commencement, and becomes shallow and a little broader as
it descends. Its borders are called, respectively, the external or posterior bicipital
ridge (crista tuberculi majoris) and the internal or anterior bicipital ridge (crista
fnhcrculi minoris}, and form the upper part of the anterior and internal borders of
the shaft of the bone. In the recent state it is covered with a thin layer of car-
tilage, lined by a prolongation of the synovial membrane of the shoulder-joint,
and receives the tendon of insertion of the Latissimus dorsi muscle.
The Shaft (corpus humeri}. — The shaft of the humerus is almost cylindrical
in the upper half of its extent, prismatic and flattened below, and presents three
borders and three surfaces for examination.
Anterior Border. — The anterior border runs from the front of the great tuber-
osity above to the coronoid depression below, separating the internal from the
external surface. Its upper part is very prominent and rough, and forms the
outer lip of the bicipital groove. It is sometimes called the posterior bicipital,
external bicipital, or pectoral ridge (crista tuberculi majoris}, and serves for the
attachment of the tendon of the Pectoralis major. About its centre it forms
the anterior boundary of the rough deltoid eminence or impression (tuberositas
deltoidea}; below, it is smooth and rounded, affording attachment to the Brachialis
anticus muscle.
External Border (margo lateralis}. — The external border runs from the back
part of the greater tuberosity to the external condyle, and separates the external
from the posterior surface. It is rounded and indistinctly marked in its upper
half, serving for the attachment of the lower part of the insertion of the Teres
minor muscle, and below this of the external head of the Triceps muscle; its
centre is traversed by a broad, but shallow, oblique depression, the musculo -spiral
groove (sulcus nervi radialis} ; its lower part is marked by a prominent, rough
margin, a little curved from behind forward, the external supracondylar or epicon-
dylic ridge (margo lateralis}, which presents an anterior lip for the attachment of
the Supinator longus above and Extensor carpi radialis longior below, a posterior
lip for the Triceps, and an intermediate space for the attachment of the external
intermuscular septum.
Internal Border (margo medialis}. — The internal border extends from the lesser
tul)erosity to the internal condyle. Its upper third is marked by a prominent
ridge, forming the posterior lip of the bicipital groove, and gives attachment to
the tendon of the Teres major. About its centre is an impression for the attach-
ment of the Coraco-brachialis, and just below this is seen the entrance of the
nutrient canal, directed downward. Sometimes there is a second canal situated
at the commencement of the musculo-spiral groove, for a nutrient artery derived
from the superior profunda branch of the brachial artery. The inferior third
of this border is raised into a slight ridge, the internal supracondylar or epicon-
dylic ridge (margo medialis}, which becomes very prominent below; it presents
an anterior lip for the attachment of the Brachialis anticus muscle, a posterior
lip for the internal head of the Triceps muscle, and an intermediate space for
the attachment of the internal intermuscular septum.
External Surface (fades anterior lateralis}. — The external surface is directed
outward above, where it is smooth, rounded, and covered by the Deltoid muscle;
forward and outward below, where it is slightly concave from above downward,
and gives origin to part of the Brachialis anticus muscle. About the middle of
this surface is seen a rough, triangular impression for the insertion of the Del-
toid muscle, deltoid impression (tuberositas deltoidea); and below it the musculo-
182
THE SKELETON
spiral groove, directed obliquely from behind,
forward and downward, and transmitting the
musculo-spiral nerve and superior profunda
artery.
Internal Surface (fades anterior medialis). —
The internal surface, less extensive than the
external, is directed inward above, forward and
inward below; at its upper part it is narrow and
forms the floor of the bicipital groove: to it is
attached the Latissimus dorsi. The middle
part of this surface is slightly rough for the
attachment of some of the fibres of the tendon
of insertion of the Coraco-brachialis ; its lower
part is smooth, concave from above downward,
and gives attachment to the Brachialis anticus
muscle.1 A little below the middle of the shaft
is the nutrient foramen (foramen nidricium).
This leads into a nutrient canal (canalis nutri-
dus), which is directed toward the elbow-joint
(distally).
Posterior Surface (fades posterior). — The pos-
terior surface (Fig. 130) appears somewhat
twisted, so that its upper part is directed a little
inward, its lower part backward and a little out-
ward. Nearly the whole of this surface is
covered by the external and internal heads of
the Triceps, the former of which is attached
to its upper and outer part, the latter to its inner
and back part, the two being separated by the
musculo-spiral groove.
Lower Extremity. — The lower extremity is
flattened from before backward, and curved
slightly forward; it terminates below in a
broad, articular surface which is divided into
two parts by a slight ridge. Projecting on
either side are the external and internal condyles
(epicondylus lateralis and epicondylus medi-
alis^. By some anatomists the external con-
dyle is called the external epicondyle and the
internal condyle is called the internal epicondyle.
i A small, hook-shaped process of bone, the aupracondylar
process, varying from '/IQ to 3/4 of an inch in length, is not infre-
quently found projecting from the inner surface of the shaft of
the humerus two inches above the internal condyle. It is curved
downward, forward, and inward, and its pointed extremity is
connected to the internal border, just above the inner condyle,
by a ligament or fibrous band, which gives origin to a portion
of the Pronator radii teres; through the arch completed by this .
fibrous band the median nerve and brachial artery pass when
these structures deviate from their usual course. Sometimes the
nerve alone is transmitted through it, or the nerve may be ac-
companied by the ulnar artery in cases of high division of the
brachial. A well-marked groove is usually found behind the
process in which the nerve and artery are lodged. This space
is analogous to the supracondyloid foramen in many animals,
and probably serves in them to protect the nerve and artery
from compression during the contraction of the muscles in this
region. A detailed account of this process is given by Dr.
Struthers, in his Anatomical and Physiological Observations, p.
202. An accessory portion of the Coraco-brachialis muscle is
frequently connected with this process, according to Mr. J. Wood _ T fi , „ , • fo/,0
(Journal of Anat. and Phys., No. 1, November, 1866, p. 47).— Fl°- 130.— Left humerus. Posterior surface.
ED. of 15th English edition.
THE HUMERUS 183
Others call the internal condyle the epitrochlea. The articular surface extends a
little lower than the condyles, and is curved slightly forward, so as to occupy the
more anterior part of the bone; its greatest breadth is in the transverse diameter,
and it is obliquely directed, so that its inner extremity occupies a lower level than
the outer. The outer portion of the articular surface presents a smooth, rounded
eminence, which has received the name of the capitellum, or radial head of the
humerus (capitulum humeri}; it articulates with the cup-shaped depression on
the head of the radius, and is limited to the front and lower part of the bone,
not extending as far back as the other portion of the articular surface. On the
inner side of this eminence is a shallow groove, in which is received the inner
margin of the head of the radius. Above the front part of the capitellum is a
slight depression, the radial fossa (fossa radialis), which receives the anterior
border of the head of the radius when the forearm is flexed. The inner por-
tion of the articular surface, the trochlea (trochlea humeri), presents a deep
depression between two well-marked borders. This surface is convex from
before backward, concave from side to side, and occupies the anterior, lower,
and posterior parts of the bone. The external border, less prominent than the
internal, corresponds to the interval between the radius and the ulna. The
internal border is thicker, more prominent, and consequently of greater length,
than the external. The grooved portion of the articular surface fits accurately
within the greater sigmoid cavity of the ulna: it is broader and deeper on the pos-
terior than on the anterior aspect of the bone, and is inclined obliquely from
behind forward and from without inward. Above the front part of the trochlear
surface is seen a smaller depression, the coronoid fossa (fossa coronoidea), which
receives the coronoid process of the ulna during flexion of the forearm. Above
the back part of the trochlear surface is a deep, triangular depression, the
olecranon fossa (fossa olecrani), in which is received the summit of the olecranon
process in extension of the forearm. These fossae are separated from one another by
a thin, transparent lamina of bone, which is sometimes perforated by a foramen,
the supratrochlear foramen; their upper margins afford attachment to the anterior
and posterior ligaments of the elbow-joint, and they are lined, in the recent state,
by the synovial membrane of this articulation. The articular surfaces, in the
recent state, are covered with a thin layer of cartilage. The external epicon-
dyle (epicondylus lateralis) is a small, tubercular eminence, less prominent
than the internal, curved a little forward, and giving attachment to the external
lateral ligament of the elbow-joint, and to a tendon common to the origin of some
of the extensor and supinator muscles. The internal epicondyle (epitrochlea or
epicondylus medialis), larger and more prominent, and therefore more liable to
fracture, than the external, is directed a little backward: it gives attachment to
the internal lateral ligament, to the Pronator radii teres, and to a tendon common
to the origin of some of the flexor muscles of the forearm. The ulnar nerve runs
in a groove, the ulnar groove (sulcus nervi ulnaris), at the back of the internal
condyle, or between it and the olecranon process. These condyles are directly
mtinuous above with the external and internal supracondylar ridges.
Structure. — The extremities consist of cancellous tissue, covered with a thin
compact layer; the shaft is composed of a cylinder of compact tissue, thicker at
the centre than at the extremities, and hollowed out by a large medullary canal,
which extends along its whole length. In the head of the humerus the plates
of the cancellous tissue are arranged in curves (Fig. 131) known as pressure
curves. Most of the bone-plates are at right angles to the plane of the articular
surface (the lines of greatest pressure), and they are bound together by other
bone-fibres, which usually correspond to the plane of the articulation (the lines
of greatest tension). This arch-like arrangement strengthens the head of the
bone, and it is further strengthened by the binding fibres.
184
THE SKELETON
Development. — By seven, or occasionally eight, centres (Fig. 133): one for the
shaft, one for the head, one for the tuberosities, one for the radial head, one for
the trochlear portion of the articular surface, and one for each condyle. The
nucleus for the shaft appears near the centre of the bone in the eighth week, and
soon extends toward the extremities. At birth the humerus is ossified nearly in
its whole length, the extremities remaining cartilaginous. During the first year,
FIG. 131. — Diagram showing the architecture of the supe-
rior extremity of the humerus. (Poirier and Charpy.)
FIG. 132. — The architecture of the superior
extremity of the humerus (x-ray picture).
Epiphyses of head and
tuberosities blend at
5th year, and unite
with shaft at 20th \
year.
Unites with shaft \
at 18th year, j
FIG. 133. — Plan of the development of the
humerus by seven centres.
sometimes even before birth, ossification
commences in the head of the bone, and
during the third year the centre for the
tuberosities makes its appearance, usually
by a single ossific point, but sometimes,
according to Beclard, by one for each
tuberosity, that for the lesser being small
and not appearing until the fifth year. By
the sixth year the centres for the head and
tuberosities have increased in size and be-
come joined, so as to form a single large
epiphysis.
The lower end of the humerus is devel-
oped in the following manner: At the end
of the second year ossification commences
in the capitellum, and from this point ex-
tends inward, so as to form the chief part
of the articular end of the bone, the centre
for the inner part of the trochlea not
appearing until about the age of twelve.
Ossification commences in the internal
condyle about the fifth year, and in the
external one not until about the thirteenth
or fourteenth year. About sixteen or seven-
teen years the outer condyle and both por-
tions of the articulating surface (which
have already joined) unite with the shaft;
THE HUMERUS 185
at eighteen years the inner condyle becomes joined; while the upper epiphysis,
although the first formed, is not united until about the twentieth year.
Articulations. — With the glenoid cavity of the scapula and with the ulna and
radius.
Attachment of the Muscles. — To twenty-four: to the greater tuberosity, the
Supraspinatus, Infraspinatus, and Teres minor; to the lesser tuberosity, the
Subscapularis ; to the anterior bicipital ridge, the Pectoralis major; to the posterior
bicipital ridge, the Teres major; to the bicipital groove, the Latissimus dorsi; to
the shaft, the Deltoid, Coraco-brachialis, Brachialis anticus, external and internal
heads of the Triceps ; to the internal condyle, the Pronator radii teres, and common
tendon of the Flexor carpi radialis, Palmaris longus, Flexor sublimis digitorum,
and Flexor carpi ulnaris; to the external condyloid ridge, the Supinator longus
and Extensor carpi radialis longior; to the external condyle, the common tendon
of the Extensor carpi radialis brevier, Extensor communis digitorum, Extensor
minimi digiti, Extensor carpi ulnaris, and Supinator brevis; to the back of the
external condyle, the Anconeus.
Surface Form. — The humerus is almost entirely clothed by the muscles which surround it,
and the only parts of this bone which are strictly subcutaneous are small portions of the
internal and external condyles. In addition to these, the tuberosities and a part of the head
of the bone can be felt under the skin and muscles by which they are covered. Of these the
greater tuberosity forms the most prominent bony point of the shoulder, extending beyond the
acromion process and covered by the Deltoid muscle. It influences materially the surface form
of the shoulder. It is best felt while the arm is lying loosely by the side; if the arm be raised,
it recedes from under the finger. The lesser tuberosity, directed forward and inward, is to be
felt to the inner side of the greater tuberosity, just below the acromio-clavicular joint. Between
the two tuberosities lies the bicipital groove. This can be defined by placing the finger and
making firm pressure just internal to the greater tuberosity; then, by rotating the humerus, the
groove will be felt to pass under the finger as the bone is rotated. With the arm abducted from
the side, by pressing deeply in the axilla the lower part of the head of the bone is to be felt.
On each side of the elbow-joint, and just above it, the internal and external condyles of the
bone are to be felt. Of these the internal is the more prominent, but the ridge passing upward
from it, the internal condyloid ridge, is much less marked than the external, and, as a rule, is
not to be felt. Occasionally, however, we find along this border the hook-shaped process men-
tioned above. The external eondyle is most plainly to be seen during semiflexion of the fore-
arm, and its position is indicated by a depression between the attachment of the adjacent mus-
cles. From it is to be felt a strong bony ridge running up the outer border of the shaft of the
bone. This is the external supracondylar ridge; it is concave forward, and corresponds with
the curved direction of the lower extremity of the humerus.
Surgical Anatomy. — There are several points of surgical interest connected with the
humerus. First, as regards its development. The upper end, though the first to ossify, is the
last to join the shaft, and the length of the bone is mainly due to growth from this upper
epiphysis. Hence, in cases of amputation of the arm in young subjects the humerus continues
to grow considerably, and the end of the bone, which immediately after the operation was cov-
ered with a thick cushion of soft tissue, begins to project, thinning the soft parts and rendering
the stump conical. This may necessitate another operation, which consists in the removal of a
couple of inches or so of the bone, and even after this operation a recurrence of the conical stump
may take place.
There are several points of surgical interest in connection with fractures. First, as regard
their causation : the bone may be broken by direct or indirect violence like the other long bones,
but, in addition to this, it is probably more frequently fractured by muscular action than any
other of this class of bone in the body. It is usually the shaft, just below the insertion of the
Deltoid, which is thus broken. Mr. Pick has seen the accident happen from throwing a stone, and
in an apparently healthy adult from cutting a piece of hard "cake tobacco" on a table. In this
latter case there was no disease of the bone that could be discovered. Fractures of the upper
end may take place through the anatomical neck, through the surgical neck, or separation of the
gmiter tuberosity may occur. Fracture of the anatomical neck is a very rare accident; in fact,
it is doubted by some whether it ever occurs. These fractures are usually considered to be
uitnicapsular, but they are probably partly within and partly without the capsule, as the lower
part of the capsule is inserted some little distance below the anatomical neck, while the upper
part is attached to it. They may be impacted or non-impacted. In most cases there is little or
186 THE SKELETON
no displacement on account of the capsule, in whole or in part, remaining attached to the lower
fragment. But occasionally a very remarkable alteration in position takes place; the upper
fragment turns on its own axis, so that the cartilaginous surface of the head rests against the
upper end of the lower fragment. When the fractured end is entirely separated from all its
surroundings, its vascular supply must be entirely cut off, and one would expect it, theoretically,
to necrose. But this must be exceedingly rare, for Gurlt was unable to find a single authenti-
cated case recorded. Separation of the upper epiphysis of the humerus sometimes occurs in the
young subject, and is marked by a characteristic deformity by which the lesion may be at once
recognized. This consists in the presence of an abrupt projection at the front of the joint some
short distance below the coracoid process, caused by the upper end of the lower fragment. In
fractures of the shaft of the humerus the lesion may take place at any point, but appears to be
more common in the lower than in the upper part of the bone. The points of interest in con-
nection with these fractures are: (1) That the musculo-spiral nerve may be injured as it lies in the
groove on the bone, or may become involved in the callus which is subsequently thrown out;
and (2) the frequency of non-union. This ic believed to be more common in the humerus than
in any other bone, and various causes have been assigned for it. It would seem most probably
to be due to the difficulty that there is in fixing the shoulder-joint and the upper fragment, and
possibly the elbow-joint and lower fragment also. Other causes which have been assigned
for the non-union are: (1) That in attempting passive motion of the elbow-joint to overcome
any rigidity which may exist, the movement does not take place at the articulation, but at the
seat of fracture; or that the patient, in consequence of the rigidity of the elbow, in attempting
to flex or extend the forearm moves the fragment and not the joint. (2) The presence of small
portions of muscular tissue between the broken ends. (3) Want of support to the elbow, so
that the weight of the arm tends to drag the lower fragment away from the upper. An impor-
tant distinction to make in fractures of the lower end of the humerus is between those that
involve the elbow-joint and those which do not ; the former are always serious, as they may lead
to stiffness of the joint and impairment of the utility of the limb. They include the T-shaped
fracture and oblique fractures which involve the articular surface. The fractures which do not
involve the joint are the transverse above the condyles and the so-called epitrochlear fracture,
in which the tip of the internal condyle is broken off, generally by direct violence.
Under the head of separation of the lower epiphysis two separate injuries have been described :
One where the whole oi the four ossific centres which form the lower extremity of the bone are
separated from the shaft; and secondly, w7here the articular portion is alone separated, the two
condyles remaining attached to the shaft of the bone. The epiphysial line between the shaft
and lower end runs across the bone just above the tips of the condyles, a point to be borne in
mind in performing the operation of excision.
Tumors originating from the humerus are of frequent occurrence. A not uncommon place
for a chondroma tc grow from is the shaft of the bone somewhere in the neighborhood of the
insertion of the deltoid. Sarcomata frequently grow from this bone.
THE FOREARM.
The forearm is that portion of the upper extremity which is situated between
the elbow and the wrist. Its skeleton is composed of two bones, the ulna and
radius.
% The Ulna or Elbow Bone.
The ulna (Figs. 134 and 135), so called from its forming the elbow ((btevy}, is a
long bone, prismatic in form, placed at the inner side of the forearm, parallel with
the radius. It is the larger and longer of the two bones. Its upper extremity, of
great thickness and strength, forms a large part of the articulation of the elbow-
joint; it diminishes in size from above downward, its lower extremity being very
small, and excluded from the wrist-joint by the interposition of an interarticular
fibro-cartilage. It is divisible into a shaft and two extremities.
Upper Extremity.— The upper extremity, the strongest part of the bone,
presents for examination two large, curved processes, the olecranon process and
the coronoid process; and two concave, articular cavities, the greater and lesser
sigmoid cavities.
Olecranon Process (olecranon). — The olecranon process (ioXivr], elbow; xixwiov,
head) is a large, thick, curved eminence situated at the upper and back part of
THE ULNA
187
Ulna.
Radius.
FLEXOR DIQITORUM
SUBLIMIS.
PBONATOR
RADII TERES.
Occasional origin of
FLEXOR LONQUS POLLIOIS.
Styloid process.
Radial origin of FLEXOR
DIQITORUM SUBLIMIS.
SUPINATOR LONQUS.
Groove for EXT. ossis
METACAR?! POLLICIS
and EXT BREV. POLL
process.
FIG. 134. — Bones of the left forearm. Anterior surface.
188 THE SKELETON
the ulna. It is curved forward at the summit so as to present a prominent tip
which is received into the olecranon fossa of the humerus in extension of the fore-
arm ; its base being contracted where it joins the shaft. This is the narrowest part
of the upper end of the ulna, and, consequently, the most usual seat of fracture.
The posterior surface of the olecranon, directed backward, is triangular, smooth,
subcutaneous, and covered by a bursa. Its upper surface is of a quadrilateral
form, marked behind by a rough impression for the attachment of the Triceps
muscle; and in front, near the margin, by a slight transverse groove for the
attachment of part of the posterior ligament of the elbow-joint. Its interior sur-
face is smooth, concave, covered with cartilage in the recent state, and forms the
upper and back part of the great sigmoid cavity. The lateral borders present
a continuation of the same groove that was seen on the margin of the superior
surface; they serve for the attachment of ligaments — viz., the back part of the
internal lateral ligament internally, the posterior ligament externally. To the
inner border is also attached a part of the Flexor carpi ulnaris, while to the outer
border is attached the Anconeus muscle.
Coronoid Process (processus coronoideus) . — The coronoid process (xopcbvy, any-
thing hooked like a crow's beak) is a triangular eminence of bone which projects
horizontally forward from the upper and front part of the ulna. Its base is con-
tinuous with the shaft, and of considerable strength; so much so that fracture of
it is an accident of rare occurrence. Its apex is pointed, slightly curved upward,
and is received into the coronoid depression of the humerus in flexion of the forearm.
Its upper surface is smooth, concave, and forms the lower part of the greater sig-
moid cavity. The under surface is concave. At the junction of this surface with
the shaft is a rough eminence, the tubercle of the ulna (tuberositas ulnae], for the
attachment of the oblique ligament of the superior radio-ulnar articulation and the
Brachialis anticus muscle. Its outer surface presents a narrow, oblong, articular
depression, the lesser sigmoid cavity. The inner surface, by its prominent, free
margin, serves for the attachment of part of the internal lateral ligament. At
the front part of this surface is a small, rounded eminence for the attachment of
one head of the Flexor sublimis digitorum; behind the eminence, a depression for
part of the origin of the Flexor profundus digitorum; and, descending from the
eminence, a ridge which gives attachment to one head of the Pronator radii teres.
Generally, the Flexor longus pollicis has an origin from the lower part of the
coronoid process by a rounded bundle of muscular fibres.
Greater Sigmoid Cavity (incisura semilunaris). — The greater sigmoid cavity, so
called from its resemblance to the old shape of the Greek letter 2', is a semi-
lunar depression of large size, formed by the olecranon and coronoid processes,
and serving for articulation with the trochlear surface of the humerus. About
the middle of either lateral border of this cavity is a notch which contracts it
somewhat, and serves to indicate the junction of the two processes of which it is
formed. The cavity is concave from above downward, and divided into two
lateral parts by a smooth, elevated ridge which runs from the summit of the
olecranon to the tip of the coronoid process. Of these two portions, the internal
is the larger, and is slightly concave transversely; the external portion is convex
above, slightly concave below. The articular surface, in the recent state, is
covered with a thin layer of cartilage.
Lesser Sigmoid Cavity (incisura radialis}. — The lesser sigmoid cavity is a narrow,
oblong, articular depression, placed on the outer side of the coronoid process, and
receives the lateral articular surface of the head of the radius. It is concave from
before backward, and its extremities, which are prominent, serve for the attach-
ment of the orbicular ligament. In the recent state it is covered with a thin layer
of cartilage.
THE ULNA
Ulna.
189
FLEXOR SUBLIMI3 DlGITORUM.
EXTENSOR CARPI ULNARI9.
EXTENSOR MINIMI D;QITI.
For
EXTENSOR CARPI RADIALIS BREVI'OR.
EXTENSOR LONQUS POLL1CIS.
FIG. 135. — Bones of the left forearm. Posterior surface.
Fnr
fEXTEN
\ EXTEN
SOR INDICIS.
SOR COMMUNIS DlGITORUM.
190 THE SKELETON
The Shaft(corpws ulnae). — The shaft, at its upper part, is prismatic in form, and
curved from behind forward and from without inward, so as to be convex behind
and externally; its central part is quite straight; its lower part rounded, smooth,
and bent a little outward ; it tapers gradually from above downward, and presents
for examination three borders and three surfaces.
Anterior or Palmar Border (mar go volaris). — The anterior border commences
above at the prominent inner angle of the coronoid process, and terminates below
in front of the styloid process. It is well marked above, smooth and rounded in
the middle of its extent, and affords attachment to the Flexor profundus digitorum :
its lower fourth, marked off from the rest of the border by the commencement of
an oblique ridge on the anterior surface, serves for the attachment^of the Pronator
quadratus. It separates the anterior from the internal surface.
Posterior or Dorsal Border (margo dorsalis). — The posterior border commences
above at the apex of the triangular subcutaneous surface at the back part of the
olecranon, and terminates below at the back part of the styloid process; it is well
marked in the upper three-fourths, and gives attachment to the aponeurosis com-
mon to the Flexor carpi ulnaris, the Extensor carpi ulnaris, and the Flexor pro-
fundus digitorum muscles; its lower fourth is smooth and rounded. This border
separates the internal from the posterior surface.
External or Interosseous Border (crista interossea). — The external or interosseous
border commences above by the union of two lines, which converge one from each
extremity of the lesser sigmoid cavity, enclosing between them a triangular space
for the attachment of part of the Supinator brevis. The external line is the
crista ra. supinatoris. The interosseous border of the ulna terminates below at
the middle of the head of the ulna. Its two middle fourths are very prominent;
its lower fourth is smooth and rounded. This border gives attachment to the
interosseous membrane, and separates the anterior from the posterior surface.
Anterior or Palmar Surface (fades volaris) . — The anterior surface, much broader
above than below, is concave in the upper three-fourths of its extent, and affords
attachment to the Flexor profundus digitorum; its lower fourth, also concave, is
covered by the Pronator quadratus. The lower fourth is separated from the
remaining portion of the bone by a prominent ridge, directed obliquely from
above downward and inward; this ridge, the oblique or pronator ridge, marks the
extent of attachment of the Pronator quadratus. At the junction of the upper
with the middle third of the bone is the nutrient foramen (foramen nutricium).
It opens into the nutrient canal (canalis nutricius), which is directed obliquely
upward and inward (proximally) .
Posterior or Dorsal Surface (fades dorsalis) . — The posterior surface, directed back-
ward and outward, is broad and concave above, somewhat narrower and convex in
the middle of its course, narrow, smooth, and rounded below. It presents, above, an
oblique ridge, which runs from the posterior extremity of the lesser sigmoid cavity,
downward to the posterior border; the triangular surface above this ridge receives
the insertion of the Anconeus muscle, whilst the upper part of the ridge itself affords
attachment to the Supinator brevis. The surface of bone below this is subdivided
by a longitudinal ridge, sometimes called the perpendicular line, into two parts;
the internal part is smooth, and covered by the Extensor carpi ulnaris; the exter-
nal portion, wider and rougher, gives attachment from above downward to part
of the Supinator brevis, the Extensor ossis metacarpi pollicis, the Extensor longus
pollicis, and the Extensor indicis muscles.
Internal Surface (fades medialis). — The internal surface is broad and concave
above, narrow and convex below. It gives attachment by its upper three-fourths
to the Flexor profundus digitorum muscle: its lower fourth is subcutaneous.
The anterior and the inner surfaces constitute the flexor surface.
THE ULNA
191
Olecranon.
Appears at^
10th year.
rins shaft at
16th year.
Lower Extremity. — The lower extremity of the ulna is of small size, and
excluded from the articulation of the wrist-joint. It presents for examination two
eminences, the outer and larger of which is a rounded, articular eminence, termed
the head of the ulna (capitulum ulnae], the inner, narrower and more projecting,
is a non-articular eminence, the styloid process (processus styloideus) . The head
presents an articular facet, part of which, of an oval or semilunar form, is
directed downward, and articulates with the upper surface of the interarticular
fibro-cartilage which separates it from the wrist-joint; the remaining portion,
directed outward, is narrow, convex, and received into the sigmoid cavity of the
radius. The peripheral margin of the portion of the head which articulates with
the ulna is called the articular circumference (circumferentia articularis). The
styloid process projects from the inner and back part of the bone, and descends
a little lower than the head, terminating in a rounded summit, which affords
attachment to the internal lateral ligament of the wrist. The head is separatee!
from the styloid process by a depression for the attachment of the triangular
interarticular fibro-cartilage; and behind, by a shallow groove for the passage of
the tendon of the Extensor carpi ulnaris.
Structure. — Similar to that of the other long bones.
Development. — By three centres : one for the shaft, one for the inferior extrem-
ity, and one for the olecranon (Fig. 136). Ossification commences near the
middle of the shaft about the eighth week, and
soon extends through the greater part of the bone.
At birth the ends are cartilaginous. About the
fourth year a separate osseous nucleus appears in
the middle of the head, which soon extends into the
styloid process. About the tenth year ossific matter
appears in the olecranon near its extremity, the chief
part of this process being formed from an extension
of the shaft of the bone into it. At about the six-
teenth year the upper epiphysis becomes joined, and
at about the twentieth year the lower one.
Articulations. — With the humerus and radius.
Attachment of Muscles. — To sixteen : to the ole-
cranon, the Triceps, Anconeus, and one head of the
Flexor carpi ulnaris. To the coronoid process, the
Brachialis anticus, Pronator radii teres, Flexor sub-
limis digitorum, and Flexor profundus digitorum;
generally also the Flexor longus pollicis. To the
shaft, the Flexor profundus digitorum, Pronator
quadratus, Flexor carpi ulnaris, Extensor carpi
ulnaris, Anconeus, Supinator brevis, Extensor ossis
metacarpi pollicis, Extensor longus pollicis, and
Extensor indicis. Inferior extremity.
FIG. 136. — Plan of the development
Surface Form.— The most prominent part of the ulna on of the ulna- By three centres-
the surface of the body is the olecranon process, which can
always be felt at the back of the elbow-joint. When the forearm is flexed, the upper quadri-
lateral surface can be felt, directed backward; during extension it recedes into the olecranon
fossa, and the contracting fibres of the triceps prevent its being perceived. At the back of
the olecranon is the smooth, triangular, subcutaneous surface, which below is continuous
with the posterior border of the shaft of the bone, and felt in every position of the forearm.
During extension the upper border of the olecranon is slightly above the level of the internal
condyle, and the process itself is nearer to this condyle than the outer one. Running down
the back of the forearm, from the apex of the triangular surface which forms the posterior
surface of the olecranon, is a prominent ridge of bone, the posterior border of the ulna.
This is to be felt throughout the entire length of the shaft of the bone, from the olecranon
above to the styloid process below. As it passes down the forearm it pursues a sinuous course
Appears at
4th year.
_Joins shaft at
20th year.
192 THE SKELETON
and inclines to the inner side, so that, though it is situated in the middle of the back of
the limb above, it is on the inner side of the wrist at its termination. It becomes rounded off
in its lower third, and may be traced below to the small, subcutaneous surface of the stvloid
process. Internal to this border the lower fourth of the inner surface is to be felt. The styloid
process is to be felt as a prominent tubercle of bone, continuous above with the posterior sub-
cutaneous border of the ulna, and terminating below in a blunt apex, which lies a little internal
and behind, but on a level with, the wrist-joint. The styloid process is best felt when the hand
is in the same line as the bones of the forearm, and in a position midway between supination
and pronation. If the forearm is pronated while the finger is placed on the process, it will be
felt to recede, and another prominence of bone will appear just behind and above it. This
is the head of the ulna, which articulates with the lower end of the radius and the triangular
interarticular fibre-cartilage, and now projects between the tendons of the Extensor carpi ulnaris
and the Extensor minimi digiti muscles.
The Radius.
The radius (radius, a ray, or spoke of a wheel) is so called because it is the
rotary bone of the forearm. It is situated on the outer side of the forearm, lying
side by side with the ulna, which exceeds it in length and size (Figs. 134 and
135). Its upper end is small, and forms only a small part of the elbow-joint;
but its lower end is large, and forms the chief part of the wrist. It is one of the
long bones, prismatic in form, slightly curved longitudinally, and, like other
long bones, has a shaft and two extremities.
Upper Extremity. — The upper extremity presents a head, neck, and tuberosity.
The Head. — The head (capitulum radii) is of a cylindrical form, depressed on
its upper surface into a shallow cup (fovea capituli radii), which articulates with
the capitellum or radial head of the humerus. In the recent state it is covered
with a layer of cartilage which is thinnest at its centre. Around the circumference
of the head is a smooth, articular surface (circumferentia articularis), broad inter-
nally where it articulates with the lesser sigmoid cavity of the ulna; narrow in
the rest of its circumference, where it rotates within the orbicular ligament. It
is coated with cartilage in the recent state. The head is supported on a round,
smooth, and constricted portion of bone, called the neck (collum radii), which
presents, behind, a slight ridge, for the attachment of part of the Supinator brevis.
Beneath the neck, at the inner and front aspect of the bone, is a rough eminence,
the bicipital tuberosity (tuberositas radii). Its surface is divided into two parts by
a vertical line — a posterior, rough portion, for the insertion of the tendon of the
Biceps muscle; and an anterior, smooth portion, on which a bursa is interposed
between the tendon and the bone.
The Shaft (corpus radii). — The shaft of the bone is prismoid in form, narrower
above than below, and slightly curved, so as to be convex outward. It presents
three surfaces, separated by three borders.
Anterior or Palmar Border (margo volaris) . — The anterior border extends from
the lower part of the tuberosity above to the anterior part of the base of the styloid
process below. It separates the anterior from the external surface. Its upper
third is very prominent; and from its oblique direction, downward and outward,
has received the name of the oblique line of the radius. It gives attachment exter-
nally to the Supinator brevis, internally to the Flexor longus pollicis, and between
these to the Flexor sublimis digitorum. The middle third of the anterior border
is indistinct and rounded. Its lower fourth is sharp, prominent, affords attach-
ment to the Pronator quadratus and to the posterior annular ligament of the wrist,
and terminates in a small tubercle at the base of the styloid process, into which
is inserted the tendon of the Supinator longus.
Posterior or Dorsal Border (margo dorsalis). — The posterior border commences
above at the back part of the neck of the radius, and terminates below at the
THE RADIUS 193
posterior part of the base of the styloid process; it separates the posterior from
t IK- external surface. It is indistinct above and below, but well marked in the
middle third of the bone.
Internal or Interosseous Border (crista interossea). — The internal or interosseous
border commences above at the back part of the tuberosity, where it is rounded
and indistinct, becomes sharp and prominent as it descends, and at its lower part
divides into two ridges, which descend to the anterior and posterior margins of
the sigmoid cavity. This border separates the anterior from the posterior sur-
face, and has the interosseous membrane attached to it throughout the greater
part of its extent.
Anterior or Palmar or Flexor Surface (fades volaris). — The anterior surface is
concave for its upper three-fourths, and gives attachment to the Flexor longus
pollicis muscle; it is broad and flat for its lower fourth, and gives attachment to
the Pronator quadratus. A prominent ridge limits the attachment of the Pro-
nator quadratus below, and between this and the inferior border is a triangular
rough surface for the attachment of the anterior ligament of the wrist-joint. At
the junction of the upper and middle third of this surface is the nutrient foramen
(foramen nutridum), the opening of the nutrient canal (canalis nutridus), which
is directed obliquely upward (proximally) .
Posterior or Dorsal or Extensor Surface (fades dorsalis). — The posterior surface
is rounded, convex, and smooth in the upper third of its extent, and covered by
the Supinator brevis muscle. Its middle third is broad, slightly concave, and gives
attachment to the Extensor ossis metacarpi pollicis above, the Extensor brevis pol-
licis below. Its lower third is broad, convex, and covered by the tendons of the
muscles, which subsequently run in the grooves on the lower end of the bone.
External Surface (fades lateralis) . — The external surface is rounded and convex
throughout its entire extent. Its upper third gives attachment to the Supinator
brevis muscle. About its centre is seen a rough ridge, for the insertion of the Pro-
nator radii teres muscle. Its lower part is narrow, and covered by the tendons
of the Extensor ossis metacarpi pollicis and Extensor brevis pollicis muscles.
Lower Extremity. — The lower extremity of the radius is large, of quadri-
lateral form, and provided with two articular surfaces — one at the extremity, for
articulation with the carpus, and one at the inner side of the bone, for articulation
with the ulna. The carpal articular surface (fades articularis carped) is of tri-
angular form, concave, smooth, and divided by a slight antero-posterior ridge
into two parts. Of these, the external is of a triangular form, and articulates with
the scaphoid bone; the inner is quadrilateral and articulates with the semilunar
bone. The articular surface for the head of the ulna is called the sigmoid cavity
of the radius (indsura ulnaris}; it is narrow, concave, smooth, and articulates
with the head of the ulna. The circumference of this end of the bone presents
three surfaces — an anterior, external, and posterior. The anterior surface, rough
and irregular, affords attachment to the anterior ligament of the wrist-joint. The
external surface is prolonged obliquely downward into a strong, conical projec-
tion, the styloid process (processus styloideus), which gives attachment by its base
to the tendon of the Supinator longus, and by its apex to the external lateral liga-
ment of the wrist-joint. The outer surface of this process is marked by a flat
groove, which runs obliquely downward and forward, and gives passage to the
tendons of the Extensor ossis metacarpi pollicis and the Extensor brevis pollicis.
The posterior surface is convex, affords attachment to the posterior ligament of
the wrist, and is marked by three grooves. Proceeding from without inward, the
first groove is broad but shallow, and subdivided into two by a slightly elevated
ridge: the outer of these two transmits the tendon of the Extensor carpi radialis
longior, the inner the tendon of the Extensor carpi radialis brevior. The second,
13
194
THE SKELETON
Head.
Appears «<j^S^^\ Unites with shaft
5th year.
about puberty.
which is near the centre of the bone, is a deep but narrow groove, bounded on its
outer side by a sharply-defined ridge; it is directed obliquely from above, down-
ward and outward, and transmits the tendon of the Extensor longus pollicis.
The third, lying most internally, is a broad groove, for the passage of the tendons
of the Extensor indicis and Extensor communis digitorum.
Structure. — Similar to that of the other long bones.
Development (Fig. 137). — By three centres: one for the shaft and one for each
extremity. That for the shaft makes its appearance near the centre of the bone,
about the eighth week of foetal life. About
the end of the second year ossification com-
mences in the lower epiphysis, and about the
fifth year in the upper end At the age of
seventeen or eighteen the upper epiphysis be-
comes joined to the shaft, the lower epiphysis
becoming united about the twentieth year.
Articulation. — With four bones : thehumerus,
ulna, scaphoid, and semilunar.
Attachment of Muscles. — To nine: to the
tuberosity, the Biceps, to the oblique ridge, the
Supinator brevis, Flexor sublimis digitorum,
and Flexor longus pollicis: to the shaft (its
anterior surface), the Flexor longus pollicis
and Pronator quadratus; (its posterior surface),
the Extensor ossis metacarpi pollicis and Exten-
sor brevis pollicis; (its outer surface), the Pro-
nator radii teres; and to the styloid process,
the Supinator longus.
*¥"? S? ataft Surface Form.— Just below and a little in front of
about zOth year. ., , . , , , , , , ,
the posterior surtace of the external condyle a part ot
the head of the radius may be felt, covered by the
orbicular and external lateral ligaments. There is in
this situation a little dimple in the skin, which is most
visible when the arm is extended,, and which marks the
position of the head of the bone. If the finger is placed on this dimple and the forearm pro-
nated and supinated, the head of the bone will be distinctly perceived rotating in the lesser
sigmoid cavity. The upper half of the shaft of the radius cannot be felt, as it is surrounded by
the fleshy bellies of the muscles arising from the external condyle. The lower half of the shaft
can be readily examined, though covered by tendons and muscles and not strictly subcutaneous.
If traced downward, the shaft will be felt to terminate in a lozenge-shaped, convex surface
on the outer side of the base of the styloid process. This is the only subcutaneous part of the
bone, and from its lower extremity the apex of the styloid process will be felt bending inward
toward the wrist. About the middle of the posterior aspect of the lower extremity of the bone
is a well-marked ridge, best perceived when the hand is slightly flexed on the wrist. It forms
the outer boundary of the oblique groove on the posterior surface of the bone, through which
the tendon of the Extensor longus pollicis runs, and serves to keep that tendon in place.
Surgical Anatomy of the Radius and Ulna. — The two bones of the forearm are more often
broken together than is either the radius or ulna separately. It is therefore convenient to consider
fractures of both bones in the first instance, and subsequently to mention the principal fractures
which take place in each bone individually. These fractures may be produced by either direct
or indirect violence, though more commonly by direct violence. When indirect force is applied
to the forearm the radius generally alone gives way, though both bones may suffer. The
fracture from indirect force generally takes place somewhere about the middle of the bones;
fracture from direct violence may occur at any part, more often, however, in the lower half of
the bone. The fracture is usually transverse, but may be more or less oblique. A point of
interest in connection with these fractures is the tendency that there is for the two bones to unite
across the interosseous membrane; the limb should therefore be put up in a position midway
between supination and pronation, which is not only the most comfortable position, but also sep-
arates the bones most widely from each other, and therefore diminishes the risk of the bones
Appears at
2d year.
Lower extremity.
FIG. 137. — Plan of the development of the
radius. By three centres.
THE CARPUS 195
becoming united across the interosseous membrane. The splints, anterior and posterior, which
are applied in these cases should be rather wider than the limb, so as to prevent any lateral
pressure on the bones. In these cases there is a greater liability to gangrene from the pressure
of the splints than in other parts of the body. This is no doubt due principally to two causes:
(1) the flexion of the forearm compressing to a certain extent the brachial artery and retarding
the flow of blood to the limb; and (2) the superficial position of the two main arteries of the
forearm in a part of their course, and their liability to be compressed by the splints. The special
fractures of the ulna are — (1) Fracture of the olecranon. This may be caused by direct violence,
falls on the elbow, with the forearm flexed, or by muscular action by the sudden contraction of
the triceps The most common place for the fracture to occur is at the constricted portion
where the olecranon joins the shaft of the bone, and the fracture may be either transverse or
oblique; but any part may be broken, even a thin shell may be torn off. Fractures from direct
violence are occasionally comminuted. The displacement is sometimes very slight, owing to the
fibrous structures around the process not being torn. (2) Fracture of the coronoid process some-
times occurs as a complication of dislocation backward of the bones of the forearm, but it is
doubtful if it ever occurs as an uncomplicated injury. (3) Fractures of the shaft of the ulna
may occur at any part, but usually takes place at the middle of the bone or a little below it.
They are almost always the result of direct violence. (4) The styloid process may be knocked
off by direct violence. Fractures of the radius consist of — (1) Fracture of the head of the bone;
this generally occurs in conjunction with some other lesion, but may occur as an uncomplicated
injury. (2) Fracture of the neck may also take place, but is generally complicated with other
injury. (3) Fractures of the shaft of the radius are very common, and may take place at any
part of the bone. They may take place from either direct or indirect violence. In fractures of the
upper third of the shaft of the bone, that is to say, above the insertion of the Pronator radii teres,
the displacement is very great. The upper fragment is strongly supinated by the Biceps and Supi-
nator brevis, and flexed by the Biceps, while the lower fragment is pronated and drawn toward
the ulna by the two pronators If such a fracture is put up in the ordinary position, midway
between supination and pronation, the fracture will unite with the upper fragment in a position
of supination, and the lower one in the mid -position, and thus considerable impairment of the
movements of the hand will result. The limb should be put up with the forearm supinated. (4)
The most important fracture of the radius is that of the lower end (Colics' 's fracture). The
fracture is transverse, and generally takes place about an inch from the lower extremity. It is
caused by falls on the palm of the hand, and is an injury of advanced life, occurring more fre-
quently in the female than the male. In consequence of the manner in which the fracture is
caused, the upper fragment becomes driven into the lower, and impaction is the result; or else
the lower fragment becomes split up into two or more pieces, so that no fixation occurs. Sepa-
ration of the lower epiphysis of the radius may take place in the young. This injury and Colles's
fracture may be distinguished from other injuries in this neighborhood — especially dislocation,
with which it is liable to be confounded— by observing the relative positions of the styloid
processes of the ulna and radius. In the natural condition of parts, with the arm hanging by the
side, the styloid process of the radius is on a lower level than that of the ulna; that is to say,
learer the ground. After fracture or separation of the epiphysis this process is on the same or
a higher level than that of the ulna, whereas it would be unaltered in position in dislocation.
THE HAND.
The skeleton of the hand is subdivided into three segments — the carpus or wrist
ines ; the metacarpus or bones of the palm ; and the phalanges or bones of the digits .
The Carpus (Ossa Carpi) (Figs. 138, 139).
The bones of the carpus (xapxoz, the wrist), eight in number, are arranged
in two rows. Those of the upper row, enumerated from the radial to the ulnar
side, are the scaphoid, semilunar, cuneiform, and pisiform; those of the lower
row, enumerated in the same order, are the trapezium, trapezoid, os magnum,
and unciform.
Common Characters of the Carpal Bones. — Each bone (excepting the pisiform)
presents six surfaces. Of these the anterior, palmar, or volar, and the posterior or
dorsal are rough for ligamentous attachment, the dorsal surface being the broader,
except in the scaphoid and semilunar. The superior or proximal and inferior or
distal are articular, the superior generally convex, the inferior concave; and the
196
THE SKELETON
internal and external are also articular when in contact with contiguous bones,
otherwise rough and tubercular. The structure in all is similar, consisting of
Carpus.
EXTENSOR CARPI
RADIALIS LONQI
EXTENSOR CARPI
RADIALIS BREVIOR.
EXTENSOR BR
POLLIC1S.
EXTENSOR LONGU
PO1.LICIS.
EXTENSOR DIGITORUM
COMMUNIS and
EXTENSOR INDICIS.
Metacarpus.
FIG. 138. — Bones of the left hand. Dorsal surface.
cancelious tissue enclosed in a layer of compact bone. Each bone is also developed
from a single centre of ossification.
THE CARPUS
197
Bones of the Upper Row.
Scaphoid or Navicular Bone (os namculare manus, the boat-like bone] (Fig.
140). — The scaphoid (axdyrj, a boat, ecdoc; , like) is the largest bone of the first
Carpus.
Groove for tendon of
FLEXOR CARPI ULNARIS
FLEXOR BREVIS MINIMI DlGITI.
FLEXOR OSSIS METACARPI
MINIMI OIQITI.
FLEXOR OSSIS
METACARPI POLLICIS.
LEXOR BREVIS POLL.
EXTEN. OS. METACARP. POLL.
EXTENSOR OSSIS
Metacarpus
FLEXOR
DIGITORUM
PROFUNDUS.
FIG. 139. — Bones of the left hand. Palmar surface.
Sesamoid
bones.
ABDUCTOR
POLLICIS.
row. It has received its name from its fancied resemblance to a boat, being
broad at one end and narrowed like a prow at the opposite. It is situated at
198 . , THE SKELETON
the upper and outer part of the carpus, its long axis being from above down-
ward, outward, and forward.
Surfaces. — The superior surface is convex, smooth, of triangular shape, and
articulates with the lower end of the radius. The inferior surface, directed
For radius.
Tuberosity.
For trapezium.^
\ For os magnum.
For trapezoid.
FIG. 140.— The left scaphoid.
downward, outward, and backward, is smooth, convex, also triangular, and
divided by a slight ridge into two parts, the external of which articulates with
the trapezium, the inner with' the trapezoid. The posterior or dorsal surface
presents a narrow, rough groove which runs the entire length of the bone and
serves for the attachment of ligaments. The anterior or palmar surface is concave
above, and elevated at its lower and outer part into a prominent rounded tuber-
osity (tuberculum ossis navicularis) , which projects forward from the front of the
carpus and gives attachment to the anterior annular ligament of the wrist and
sometimes a few fibres of the Abductor pollicis. The external surface is rough
and narrow, and gives attachment to the external lateral ligament of the wrist.
The internal surface presents two articular facets : of these, the superior or smaller
one is flattened, of semilunar form, and articulates with the semilunar; the inferior
or larger is concave, forming, with the semilunar bone, a concavity for the head
of the os magnum.
To ascertain to which side the bone belongs, hold it with the superior or radial
convex, articular surface upward, and the posterior surface — i. e., the narrow,
non-articular, grooved surface — toward you. The tubercle on the outer surface
points to the side to which the bone belongs.1
Articulations. — With five bones: the radius above, trapezium and trapezoid
below, os magnum and semilunar internally.
Attachment of Muscles. — Occasionally a few fibres of the Abductor pollicis.
Semilunar (os lunatum) (Fig. 141). — The semilunar (semi, half; luna, moon)
bone may be distinguished by its deep concavity and crescentic outline. It is
For cuneiform. For radius.
For
For unciform. \ scaphoid.
For os magnum.
FIG. 141. — The left semilunar.
situated in the centre of the upper row of the carpus, between the scaphoid and
cuneiform.
Surfaces. — The superior surface, convex, smooth, and bounded by four edges,
articulates with the radius. The inferior surface is deeply concave, and of greater
1 In these directions each bone is supposed to be placed in its natural position — that is, such a position as it
would occupy when the arm is hanging by the side, the forearm in a position of supination, the thumb being
directed outward, and the palm of the hand looking forward. — ED. of 15th English Edition.
199
For semilunar.
For pisiform.
For unciform.
FIG. 142.— The left cunei-
form.
extent from before backward than transversely : it articulates with the head of the
os magnum and by a long, narrow, facet (separated by a ridge from the general
surface) with the unciform bone. The anterior or palmar and posterior or dorsal
surfaces are rough, for the attachment of ligaments, the former being the broader
and of a somewhat rounded form. The external surface presents a narrow, flat-
tened, semilunar facet for articulation with the scaphoid. The internal surface
is marked by a smooth, quadrilateral facet, for articulation with the cuneiform.
Hold it with the convex articular surface for the radius upward, and the nar-
rowest non-articular surface toward you. The semilunar facet for the scaphoid
will be on the side to which the bone belongs.
Articulations. — With five bones: the radius above, os magnum and unciform
below, scaphoid and cuneiform on either side.
Cuneiform (os triquetrum, the wedge-shaped bone) (Fig. 142). — The cuneiform
(cuneus, a wedge; forma, likeness) may be distinguished by its pyramidal
shape, and by its having an oval, isolated facet for articu-
lation with the pisiform bone. It is situated at the upper
and inner side of the carpus.
Surfaces. — The superior surface presents an internal, rough,
non-articular portion, and an external or articular portion,
which is convex, smooth, and articulates with the triangular
interarticular fibro-cartilage of the wrist. The inferior sur-
face, directed outward, is concave, sinuously curved, and
smooth for articulation with the unciform. The posterior
or dorsal surface is rough, for the attachment of ligaments. The anterior or
palmar surface presents, at its inner side, an oval facet, for articulation with
the pisiform; and is rough externally, for ligamentous attachment. The exter-
nal surface, the base of the pyramid, is marked by a flat, quadrilateral, smooth
facet, for articulation with the semilunar. The internal surface, the summit of
the pyramid, is pointed and roughened, for the attachment^ the internal lateral
ligament of the wrist.
Hold the bone with the surface supporting the pisiform facet away from you,
and the concavo-convex surface for the unciform downward. The base of the
wedge (i. e., the broad end of the bone) will be on the side to which it belongs.
Articulations. — With three bones: the semilunar externally, the pisiform in
front, the unciform below; and with the triangular, interarticular fibro-cartilage
which separates it from the lower end of the ulna.
Pisiform (os pisifarme) (Fig. 143). — The pisiform (pisum, a pea; forma, like-
ness) may be known by its small size and by its presenting a single articular
facet. It is situated on a plane anterior to the other bones of
the carpus; it is spheroidal in form, with its long diameter
directed vertically.
Surfaces. — Its posterior surface is a smooth, oval facet, for
articulation with the cuneiform. This facet approaches the
superior, but not the inferior border of the bone. The anterior
or palmar surface is rounded and rough, and gives attachment
to the anterior annular ligament and to the Flexor carpi
ulnaris and Abductor minimi digiti muscles. The outer and inner surfaces are
ilso rough, the former being concave, the latter usually convex.
Hold the bone with the posterior surface — that which presents the articular
facet — toward you, in such a manner that the faceted portion of the surface is
ippermost. The outer, concave surface will point to the side to which it belongs.
Articulations. — With one bone, the cuneiform.
Attachment of Muscles. — To two: the Flexor carpi ulnaris and Abductor
linimi digiti; and to the anterior annular ligament.
For
cuneiform.
FIG. 143.— The left
pisiform.
200 THE SKELETON
Bones of the Lower Row. \
Trapezium (os multangulum majus) (Fig. 144). — The trapezium (rpd^s^a, a
table) is of very irregular form. It may be distinguished by a deep groove, for
For trapezoid. _ L Ridge
Groove. For scaphoid.
For trapezoid.
For 3d
metacarpal.'
For 1st metacarpal. For2d metacarpal.
FIG. 144. — The left trapezium.
the tendon of the Flexor carpi radialis muscle. It is situated at the external and
inferior part of the carpus between the scaphoid and first metacarpal bone.
Surfaces. — The superior surface, concave and smooth, is directed upward and
inward, and articulates with the scaphoid. The inferior surface, directed down-
ward and inward, is oval, concave from side to side, convex from before backward,
so as to form a saddle-shaped surface, for articulation with the base of the first
metacarpal bone. The anterior or palmar surface is narrow and rough. At its
upper part is a deep groove running from above obliquely downward and inward ;
it transmits the tendon of the Flexor carpi radialis, and is bounded externally
by a prominent ridge, the oblique ridge of the trapezium (tuberculum ossis mul-
tanguli majoris). This surface gives attachment to the Abductor pollicis, Flexor
ossis metacarpi pollicis, and Flexor brevis pollicis muscles, and the anterior
annular ligament. The posterior or dorsal surface is rough. The external sur-
face is also broad and rough, for the attachment of ligaments. The internal
surface presents two articular facets: the upper one, large and concave, articu-
lates with the trape»oid; the lower one, small and oval, with the base of the
second metacarpal bone.
Hold the bone with the saddle-shaped surface downward and the grooved
surface away from you. The prominent, rough, non-articular surface points to
the side to which the bone belongs.
Articulations. — With four bones: the scaphoid above, the trapezoid and second
metacarpal bones internally, the first metacarpal below.
Attachment of Muscles. — Abductor pollicis, Flexor ossis metacarpi pollicis, and
part of the Flexor brevis pollicis.
Trapezoid (05 multangulum minus) (Fig. 145). — The trapezoid is the smallest
bone in the second row. It may be known by its wedge-shaped form, the broad
Anterior surface.
For scaphoid. I For trapezium.
For os magnum.
Post, surface.
For 2d metacarpal.
FIG. 145. — The left trapezoid.
end of the wedge forming the dorsal, the narrow end the palmar, surface, and by
its having four articular surfaces touching each other and separated by sharp
edges.
Surfaces. — The superior surface, quadrilateral in form, smooth, and slightly con-
cave, articulates with the scaphoid. The inferior surface articulates with the upper
THE CARPUS 201
end of the second metacarpal bone ; it is convex from side to side, concave from before
backward, and subdivided by an elevated ridge into two unequal lateral facets.
The posterior or dorsal and anterior or palmar surfaces are rough, for the attach-
ment of ligaments, the former being the larger of the two. The external surface,
convex and smooth, articulates with the trapezium. The internal surface is con-
cave and smooth in front, for articulation with the os magnum; rough behind,
for the attachment of an interosseous ligament.
Hold the bone with the larger, non-articular surface toward you, and the
smooth, quadrilateral articular surface upward. The convex articular surface
will point to the side to which the bone belongs.1
Articulations. — With four bones: the scaphoid above, second metacarpal bone
below, trapezium externally, os magnum internally.
Os Magnum (os capitatum) (Fig. 146). — The os magnum is the largest bone
of the carpus, and occupies the centre of the wrist. It presents, above, a rounded
_For semilunar. For semilunar.
For scaphoid.*
For unciform.
For 3d
metacarpal.-^—j^^H «A
^as^*jjm^ For 4th
/ x^^^P metacarpal.
For 3d For 4th metacarpal.
metacarpal.
FIG. 146. — The left os magnum.
portion or head, which is received into the concavity formed by the scaphoid and
semilunar bones; a constricted portion or neck; and, below, the body.
Surfaces. — The superior surface is rounded, smooth, and articulates with the semi-
lunar. The inferior surface is divided by two ridges into three facets for articulation
with the second, third, and fourth metacarpal bones, that for the third (the middle
facet) being the largest of the three. The posterior or dorsal surface is broad and
rough; the anterior or palmar, narrow, rounded, and also rough, for the attachment
of ligaments and a part of the Adductor obliquus pollicis. The external surface
articulates with the trapezoid by a small facet at its anterior inferior angle, behind
which is a rough depression for the attachment of an interosseous ligament.
Above this is a deep and rough groove, which forms part of the neck and serves
for the attachment of ligaments, bounded superiorly by a smooth, convex surface,
for articulation with the scaphoid. The internal surface articulates with the unci-
form by a smooth, concave, oblong facet which occupies its posterior and superior
parts, and is rough in front, for the attachment of an interosseous ligament.
Hold the bone with the broader, non-articular surface toward you, and the
head upward. The small, articular facet at the anterior inferior angle of the
external surface will point to the side to which the bone belongs.
Articulations. — With seven bones: the scaphoid and semilunar above; the
second, third, and fourth metacarpal below; the trapezoid on the radial side; and
the unciform on the ulnar side.
Attachment of Muscles. — Part of the Adductor obliquus pollicis.
Unciform (os hamatum) (Fig. 147). — The unciform or hook bone (uncus, a hook;
forma, likeness) may be readily distinguished by its wedge-shaped form and the
hook-like process that projects from its palmar surface. It is situated at the inner
1 Occasionally in a badly marked bone there is some difficulty in ascertaining to which side the bone belongs;
the following method will sometimes be found useful: Hold the bone with its broader, non-articular surface
upward, so that its sloping border i.s directed toward you. The border will slope to the side to which the bone
belongs. — ED. of 15th English Edition.
202 THE SKELETON
and lower angle of the carpus, with its base downward, resting on the two inner
metacarpal bones, and its apex directed upward and outward.
Surfaces. — The superior surface, the apex of the wedge, is narrow, convex,
smooth, and articulates with the semilunar. The inferior surface articulates with
For semilunar.
For os magnum.
' * *• -For cuneiform.
For fourth meta
carpal.
Unciform process. ^*V JetLarpal.
FIG. 147. — The left unciform.
the fourth and fifth metacarpal bones, the concave surface for each being sepa-
rated by a ridge which runs from before backward. The posterior or dorsal
surface is triangular and rough, for ligamentous attachment. The anterior or
palmar surface presents, at its lower and inner side, a curved, hook-like pro-
cess of bone, the unciform process (hamulus ossis hamati), directed from the
palmar surface forward and outward. It gives attachment by its apex to the
annular ligament and Flexor carpi ulnaris; by its inner surface to the Flexor brevis
minimi digiti and the Opponens minimi digiti; and is grooved on its outer
side, for the passage of the Flexor tendons into the palm of the hand. This is
one of the four eminences on the front of the carpus to which the anterior
annular ligament is attached, the others being the pisiform internally, the oblique
ridge of the trapezium and the tuberosity of the scaphoid externally. The internal
surface articulates with the cuneiform by an oblong facet cut obliquely from above,
downward and inward. The external surface articulates with the os magnum by
its upper and posterior part, the remaining portion being rough, for the attach-
ment of ligaments.
Hold the bone with the hooked process away from you, and the articular sur-
face, divided into two parts, for the metacarpal bones, downward The concavity
of the process will be on the side to which the bone belongs.
Articulations. — With five bones: the semilunar above, the fourth and fifth
metacarpal below, the cuneiform internally, the os magnum externally.
Attachment of Muscles. — To three: the Flexor brevis minimi digiti, the Opponens
minimi digiti, the Flexor carpi ulnaris.
The Metacarpus (Ossa Metacarpalia) (Figs. 138, 139).
The metacarpal bones are five in number, and they are numbered from 1 to
5 inclusive, the first being the metacarpal bone of the thumb, the fifth the
metacarpal bone of the index finger. They are long, cylindrical bones, pre-
senting for examination a shaft and two extremities.
Common Characters of the Metacarpal Bones. The Shaft (corpus). — The
shaft is prismoid in form and curved longitudinally, so as to be convex in the
longitudinal direction behind, concave in front. It presents three surfaces:
two lateral and one posterior. The two lateral surfaces constitute the palmar or
volar surface. The lateral surfaces are concave, for the attachment of the Inter-
ossei muscles, and separated from one another by a prominent anterior ridge.
The posterior or dorsal surface presents in its distal half a smooth, triangular, flat-
tened area which is covered, in the recent state, by the tendons of the Extensor
muscles. This triangular surface is bounded by two lines, which commence in
THE METACARPUS
203
small tubercles situated on the dorsal aspect on either side of the digital extremity,
and, running backward, converge to meet together a little behind the centre of
the bone and form a ridge which runs along the rest of the dorsal surface to the
carpal extremity. This ridge separates two lateral, sloping surfaces for the
attachment of the Dorsal interossei muscles.1 To the tubercles on the digital
extremities are attached the lateral ligaments of the metacarpo-phalangeal joints.
On the palmar surface of each metacarpal bone is a nutrient foramen (foramen
nutricium), which opens into a nutrient canal (canalis nutricius). ' In the thumb
metacarpal the direction of this foramen is toward the periphery (distally). In
each of the other metacarpals it is from the periphery (proximally) .
Carpal or Proximal Extremity or Base (basis) . — The carpal extremity, or base,
is of a cuboidal form, and broader behind than in front; it articulates above
with the carpus, and on each side with the adjoining metacarpal bones ; its dorsal
and palmar surfaces are rough, for the attachment of tendons and ligaments.
Digital or Distal Extremity or Head (capitulum). — The digital extremity, or head,
presents an oblong surface, markedly convex from before backward, less so from
side to side, and flattened laterally; it articulates with the proximal phalanx; it is
broader and extends farther forward on the palmar than on the dorsal aspect. It
is longer in the antero-posterior than in the transverse diameter. On either side of
the head is a tubercle for the attachment of the lateral ligament of the metacarpo-
phalangeal joint. The posterior surface, broad and flat, supports the Extensor
tendons; the anterior surface is grooved in the middle line for the passage of the
Flexor tendons, and marked on each side by an articular eminence continuous with
the terminal articular surface. The metacarpal spaces (spatia interossea metacarpi)
are the intervals between the metacarpal bones. They are occupied by the
Interossei muscles. The broadest space is between the metacarpal bones of the
thumb and index finger.
Peculiar Characters of the Metacarpal Bones. — The Metacarpal Bone of the
Thumb (os metacarpale I) (Fig. 148) is shorter and wider than the rest, diverges to a
greater degree from the carpus, and its palmar sur-
face is directed inward toward the palm. The shaft
is flattened and broad on its dorsal aspect, and
does not present the ridge which is found on the
other metacarpal bones ; it is concave from above
downward, on its palmar surface. The carpal
extremity, or base, presents a concavo-convex sur-
face, for articulation with the trapezium; it has
no lateral facets, but presents externally a tubercle
for the insertion of the Extensor ossis metacarpi
pollicis. The digital extremity is less convex than
that of the other metacarpal bones, broader from
side to side than from before backward. It pre-
sents on its palmar aspect two distinct articular
eminences for the two sesamoid bones in the ten-
dons of the Flexor brevis pollicis, the outer one
being the larger of the two.
The side to which this bone belongs may be known by holding it in the position
it occupies in the hand, with the carpal extremity upward and the dorsal surface
backward; the tubercle for the Extensor ossis metacarpi pollicis will point to the
side to which it belongs.
Attachment of Muscles. — To four: the Flexor ossis metacarpi pollicis, the Extensor
ossis metacarpi pollicis, the Flexor brevis pollicis, and the First dorsal interosseous.
1 By these sloping surfaces the metacarpal bones of the hand may be at once differentiated from the meta-
tarsal bone of the foot. — ED. of 15th English Edition.
Tubercle.
For trapezium. For trapezium.
FIG. 148.— The first metacarpal. (Left.)
204
THE SKELETON
The Metacarpal Bone of the Index Finger (os metacarpale II) (Fig. 149) is the
longest and its base the largest of the other four. Its caxpal extremity is prolonged
upward and inward, forming a prominent ridge. The dorsal and palmar surfaces
of this extremity are rough, for the attachment of tendons and ligaments. It pre-
sents four articular facets: three on the upper aspect of the base: the middle one of
the three is the largest, concave from side to side, convex from before backward, for
articulation with the trapezoid; the external one is a small, flat, oval facet,' for
articulation with the trapezium ; the internal one on the summit of the ridge is long
and narrow, for articulation with the os magnum. The fourth facet is on the inner
or ulnar side of the extremity of the bone, and is for articulation with the third
metacarpal bone.
The side to which this bone belongs is indicated by the absence of the lateral
facet on the outer (radial) side of its base, so that if the bone is placed with the
base toward the student and the palmar surface upward, the side on which there
is no lateral facet will be that to which it belongs.
trapezium. j For third metacarpaL
For trapesoid. For os magnum.
FIG. 149. — The second metacarpal. (Left.)
For fourth
metacarpal.
Styloid For second
process, metacarpal.
For os magnum.
FIG. 150. — The third metacarpal. (Left.)
Attachment of Muscles. — To six: Flexor carpi radialis, Extensor carpi radialis
longior, Adductor obliquus pollicis, First and Second dorsal interosseous, and
First palmar interosseous.
The Metacarpal Bone of the Middle Finger (os metacarpale III) (Fig. 150) is a
little smaller than the preceding: it presents a pyramidal eminence, the styloid
process (processus styloideus) , on the radial side of its base (dorsal aspect), which
extends upward behind the os magnum; immediately below this, on the dorsal
aspect, is a rough surface for the attachment of the Extensor carpi radialis brevior.
The carpal, articular facet is concave behind, flat in front, and articulates with the
os magnum. On the radial side is a smooth, concave facet, for articulation with
the second metacarpal bone, and on the ulnar side two small, oval facets, for articu-
lation with the fourth metacarpal.
The side to which this bone belongs is easily recognized by the styloid process
on the radial side of its base. With the palmar surface uppermost and the base
toward the student, this process points toward the side to which the bone belongs.
THE METACARPUS
205
Attachment of Muscles. — To six: Extensor carpi radialis brevior, Flexor carpi
radialis, Adductor transversus pollicis, Adductor obliquus pollicis, and Second and
Third dorsal interosseous.
The Metacarpal Bone of the Ring Finger (os metacarpale IV) (Fig. 151) is shorter
and smaller than the preceding,- and its base small and quadrilateral; the carpal
surface of the base presenting two facets, a large one externally, for articulation
with the unciform, and a small one internally, for the os magnum. On the radial
side are two oval facets, for articulation with the third metacarpal bone; and on
the ulnar side a single concave facet, for the fifth metacarpal.
If this bone is placed with* the base toward the student and the palmar surface
upward, the radial side of the base, which has two facets for articulation with the
third metacarpal bone, will be on the side to which it belongs. If, as sometimes
happens in badly marked bones, one of these facets is indistinguishable, the side
may be known by selecting the surface on which the larger articular facet is present.
This facet is for the fifth metacarpal bone, and would therefore be situated on the
ulnar side — that is, the one to which the bone does not belong.
For third I For fifth metn-
metacarpal. For os carpal
For unciform.
FIG. 151. — The fourth metacarpal. (Left.)
,v
For fourth For cuneiform,
metacarpal.
FIG. 152. — The fifth metacarpal. (Left.)
Attachment of Muscles. — To three: the Third and Fourth dorsal and Second
palmar interosseous.
The Metacarpal Bone of the Little Finger (os metacarpale V) (Fig. 152) presents on
its base one facet, which is concavo-convex, and which articulates with the unciform
bone, and one lateral, articular facet, which articulates with the fourth metacarpal
bone. On its ulnar side is a prominent tubercle, for the insertion of the tendon of
the Extensor carpi ulnaris. The dorsal surface of the shaft is marked by an oblique
ridge which extends from near the ulnar side of the upper extremity to the radial
side of the lower. The outer division of this surface serves for the attachment of
the Fourth dorsal interosseous muscle; the inner division is smooth and covered
by the Extensor tendons of the little finger.
If this bone is placed with its base toward the student and its palmar surface
upward, the side of 'the head which has a lateral facet will be that to which the
bone belongs.
Attachment of Muscles. — To five: the Extensor carpi ulnaris, Flexor carpi
ulnaris, Flexor ossis metacarpi minimi digiti, Fourth dorsal, and Third palmar
interosseous.
206 THE SKELETON
Articulations. — Besides the phalangeal articulations, the first metacarpal bone
articulates with the trapezium; the second with the trapezium, trapezoid, os
magnum, and third metacarpal bones; the third with the os magnum and second
and fourth metacarpal bones; the fourth with the os magnum, unciform, and
third and fifth metacarpal bones; and the fifth with the unciform and fourth
metacarpal.
The first has no lateral facets on its carpal extremity; the second has no lateral
facet on its radial side, but one on its ulnar side; the third has one on its radial
and two on its ulnar side; the fourth has two on its radial and one on its ulnar
side; and the fifth has only one on its radial side.
The Phalanges of the Hand (Phalanges Digitorum Manus).
The phalanges (internodia) are the bones of the fingers; they are fourteen in
number, three for each finger, and two for the thumb. In numbering them the
proximal bone is designated as the first phalanx (phalanx I) . They are long bones,
and present for examination a shaft and two extremities. The shaft (corpus
phalangis) tapers from above downward, is convex posteriorly, concave in front
from above downward, flat from side to side, and marked laterally by rough
ridges, which give attachment to the fibrous sheaths of the Flexor tendons. A
nutrient foramen on the palmar surface leads into a nutrient canal which runs
toward the periphery (distalward) . The metacarpal extremity or base (basis
phalangis) of each phalanx in the first row presents an oval, concave, articular
surface, broader from side to side than from before backward; and the same
extremity in the other two rows, a double concavity, separated by a longitudinal
median ridge, extending from before backward. The distal extremity of the first
phalanx of the thumb and of the first and second phalanx of each of the fingers is
smaller than the base, and terminates in two small, lateral condyles, separated
by a slight groove (trochlea phalangis) ; the articular surface being prolonged far-
ther forward on the palmar than on the dorsal surface, especially in the first row.
The Ungual Phalanges (distal) are convex on their dorsal, flat on their palmar,
surfaces; they are recognized by their small size and by a roughened, elevated
surface of a horseshoe form on the palmar aspect of their ungual extremity
(tuberositas unguicularis) , which serves to support the sensitive pulp of the finger.
Articulations. — The first row, with the metacarpal bones and the second row of
phalanges; the second row, with the first and third; the third, with the second row.
Attachment of Muscles. — To the base of the first phalanx of the thumb, five
muscles: the Extensor brevis pollicis, Flexor brevis pollicis, Abductor pollicis,
Adductor transversus and Obliquus pollicis. To the second phalanx, two: the
Flexor longus pollicis and the Extensor longus pollicis. To the base of the first
phalanx of the index finger, the First dorsal and the First palmar interosseous; to
that of the middle finger, the Second and Third dorsal interosseous; to that of
the ring finger, the Fourth dorsal and the Second palmar interosseous ; and to that
of the little finger, the Third palmar interosseous, the Flexor brevis minimi digiti,
and Abductor minimi digiti. To the second phalanges, the Extensor sublimis digi-
torum, Extensor communis digitorum, and, in addition, the Extensor indicis to
the index finger, the Extensor minimi digiti to the little finger. To the third
phalanges, the Flexor profundus digitorum and Extensor communis digitorum.
Surface Form. — On the front of the wrist are two subcutaneous eminences, one on the
radial side, the larger and flatter, due to the tuberosity of the scaphoid and the ridge on the
trapezium; the other, on the ulnar side, caused by the pisiform bone. The tubercle of the
scaphoid is to be felt just below and in front of the apex of the styloid process of the radius. It
is best perceived by extending the hand on the forearm. Immediately below is to be felt
another prominence, better marked than the tubercle; this is the ridge on the trapezium which
gives attachment to some of the short muscles of the thumb. On the inner side of the front of
DEVELOPMENT OF THE BONES OF THE HAND 207
.e wrist the pisiform bone is to be felt, forming a small but prominent projection in this situa-
jn. It is some distance below the styloid process of the ulna, and may be said to be just below
ic level of the styloid process of the radius. The rest of the front of the carpus is covered by
•ndons and the annular ligament, and entirely concealed, with the exception of the hooked
process of the unciform, which can only be made out with difficulty. The back of the carpus is
convex and covered by the Extensor tendons, so that none of the posterior surfaces of the bones
arc to be felt, with the exception of the cuneiform on the inner side. Below the carpus the
dorsal surfaces of the metacarpal bones, except the fifth, are covered by tendons, and are scarcely
visible except in very thin hands. The dorsal surface of the fifth is, however, subcutaneous
throughout almost its whole length, and is plainly to be perceived and felt. In addition to this,
slightly external to the middle line of the hand, is a prominence, frequently well marked, but
occasionally indistinct, formed by the base of the metacarpal of the middle finger. The heads of
thr metacarpal bones are plainly to be felt and seen, rounded in contour and standing out in bold
relict' under the skin, when the fist is clenched. It should be borne in mind that when the fin-
gers are flexed on the hand, the articular surfaces of the first phalanges glide off the heads of the
metacarpal bones on to their anterior surfaces, so that the head of these bones form the prom-
inence of the knuckles and receive the force of any blow which may be given. The head of the
third metacarpal bone is the most prominent, and receives the greater part of the shock of the
blow. This bone articulates with the os magnum, so that the concussion is carried through this
bone to the scaphoid and semilunar, with which the head of the os magnum articulates, and by
these bones is transferred to the radius, along which it may be carried to the capitellum of the
humerus. The enlarged extremities of the phalanges are to be plainly felt: they form the
joints of the fingers. When the digits are bent the proximal phalanges of the joints form
prominences, which in the joint between the first and second phalanges is slightly hollowed, in
accordance with the grooved shape of their articular surfaces, whilst at the last row the prom-
inence is flattened and square-shaped. In the palm of the hand the four inner metacarpal bones
are covered by muscles, tendons, and the palmar fascia, and no part of them but their heads
is to be distinguished. With regard to the thumb, on the dorsal aspect the base of the meta-
carpal bone forms a prominence below the styloid process of the radius; the shaft is to be felt,
covered by tendons, terminating at its head in a flattened prominence, in front of which can be
felt the sesamoid bones.
Surgical Anatomy. — The carpal bones are not very liable to fracture, except from extreme
violence, when the parts may be so comminuted as to necessitate amputation. Occasionally they
are the seat of tuberculous disease. The metacarpal bones and the phalanges are not unfrequently
broken by direct violence. The first metacarpal bone is the one most commonly fractured;
then the second, the fourth, and the fifth, the third being the one least frequently broken. There
are two diseases of the metacarpal bones and phalanges which require special mention on
account of the frequency of their occurrence. One is tuberculous dactylitis, consisting in a
deposit of tuberculous material in the medullary canal, expanding the bone, with subsequent
caseation and resulting necrosis. The other is chondroma, which is perhaps more frequently
found in connection with the metacarpal bones and phalanges than with any other bones. When
chondromatous growth takes place there are usually multiple tumors, and they may spring
either from the medullary canal or from the periosteum.
Development of the Bones of the Hand.
The Carpal Bones are each developed by a single centre. At birth they are
all cartilaginous. Ossification proceeds in the following order (Fig. 153) : In the
os magnum and unciform an ossific point appears during the first year, the former
preceding the latter; in the cuneiform, at the third year; in the trapezium and
semilunar, at the fifth year, the former preceding the latter; in the scaphoid, at
the sixth year; in the trapezoid, during the eighth year; and in the pisiform, about
the twelfth year.
Occasionally an additional bone, the os centrale, is found in the carpus, lying
between the scaphoid, trapezoid, and os magnum. During the second month of
foetal life it is represented by a small cartilaginous nodule, which, however,
fuses with the cantilaginous scaphoid about the third month. Sometimes the
styloid process of the third metacarpal is detached and forms an additional
ossicle.
The Metacarpal Bones are each developed by two centres: one for the shaft
and one for the digital extremity for the four inner metacarpal bones; one for the
shaft and one for the base for the metacarpal bone of the thumb, which in this
208
THE SKELETON
respect resembles the phalanges.1 Ossification commences in the centre of the
shaft about the eighth or ninth week, and gradually proceeds to either end of the
bone: about the third year the digital extremities of the four inner metacarpal
bones and the base of the first metacarpal begin to ossify, and they unite about
the twentieth year.
Carpus.
One centre for each bone.
All cartilaginous at birth.
Metacarpus.
Two centres for each bone :
One for shaft,
One for digital extremity,
except first.
Phalanges.
Two centres for each bone :
One for shaft,
One for metacarpal
extremity.
At^A .Appears 3rd year.
• i *- y . \
Unite 20th year.
.Appears 8th week.
) Unite
20th, year.
, \Appears 3rd year
ad i
•s Uh-5th year.
I Unite ISth^ZOlh year.
Appears 8th week.
Appears Uh-Sth year.
I Unite 18th-20 year.
'^Appears 8th week.
FIG. 153. — Plan of the development of the hand.
The Phalanges are each developed by two centres; one for the shaft and one
for the base. Ossification commences in the shaft, in all three rows, at about the
eighth week, and gradually involves the whole of the bone excepting the upper
extremity. Ossification of the base commences in the first row between the third
and fourth years, and a year later in those of the second and third rows. The two
centres become united, in each row, between the eighteenth and twentieth years.
In the ungual phalanges the centre for the shaft appears at the distal extremity
of the phalanx, instead of at the middle of the shaft, as is the case with the other
phalanges.
THE LOWER EXTREMITY.
The bones of the lower extremity consist of those of the pelvis, of the thigh, of
the leg, and of the foot.
THE PELVIS
209
THE PELVIS (Figs. 154, 155).
The pelvis, so called from its resemblance to a basin (L. pelvis}, is stronger
and more massively constructed than either the cranial or thoracic cavity; it is a
bony ring, interposed between the lower end of the spine, which it supports, and
the lower extremities, upon which its rests. It is composed of four bones: the two
ossa innominata, which bound it on either side and in front, and the sacrum and
coccyx, which complete it behind. The pelvis is divided by an oblique plane
passing through the prominence of the sacrum, the linea ilio-pectinea, and the
upper margin of the symphysis pubis into the false and true pelvis.
The False Pelvis (pelvis major) . — The false pelvis is the expanded portion of
the pelvic cavity which is situated above this plane. It is bounded on each side
by the ossa ilii; in front it is incomplete, presenting a wide interval between the
spinous processes of the ilia on either side, which is filled up in the recent state by
the parietes of the abdomen; behind, in the middle line, is a deep notch. This
broad, shallow cavity is fitted to support the t intestines and to transmit part of
their weight to the anterior wall of the abdomen, and is, in fact, really a portion
of the abdominal cavity. The term false pelvis is incorrect, and this space ought
FIG. 154. — Male pelvis (adult).
more properly to be regarded as part of the hypogastric and iliac regions of the
abdomen.
The True Pelvis (pelvis minor), — The true pelvis is that part of the pelvic
cavity which is situated beneath the plane. It is smaller than the false pelvis,
but its walls are more perfect. For convenience of description it is divided
into a superior circumference or inlet, an inferior circumference or outlet, and a
cavity.
The Superior Circumference or Inlet (apertura pelvis superior}. — The superior cir-
cumference forms the brim of the pelvis, the included space being called the inlet.
It is formed by the linea ilio-pectinea, completed in front by the crests of the
pubic bones, and behind by the anterior margin of the base of the sacrum and
sacro-vertebral angle. The brim of the pelvis is the name often given to the
14
210
THE SKELETON
margin of the inlet. The inlet of the pelvis is somewhat heart-shaped, obtusely
pointed in front, diverging on either side, and encroached upon behind by the
projection forward of the promontory of the sacrum. It has three principal
diameters: antero-posterior (sacro-pubic), transverse, and oblique. The antero-
posterior or conjugate diameter (conjugata) extends from the sacro-vertebral angle
to the symphysis pubis. The anatomical conjugate (conjugata anatomica) is the
distance between the sacro-vertebral angle and the top of the symphysis pubis.
Its average measurement is four inches in the male and four and three-fifths inches
in the female. The true, available, or obstetric conjugate (conjugata gynascologica]
is the distance between the sacro-vertebral angle and the nearest point upon the
symphysis. This point is a little behind and below the upper margin (Webster).
FIG. 155.— Female pelvis (adult).
The average distance in women is four and three-eighths inches. The diagonal
conjugate (diagonalconjugata) is measured from the sacro-vertebral angle to the
subpubic ligament. The distance exceeds the true conjugate by one-half or two-
thirds of an inch. The transverse diameter (diameter transversa) extends across
the greatest width of the inlet, from the middle of the brim on one side to the
same point on the opposite; its average measurement is five inches in the male,
five and one-fourth inches in the female. The oblique diameter (diameter obliqua)
extends from the margin of the pelvis, corresponding to the ilio-pectineal eminence
on one side, to the sacro-iliac articulation on the opposite side; its average
measurement is four and a quarter inches in the male and five in the female. The
oblique diameters are named right or left oblique, according to the sacro-iliac
joint from which the measurement is taken.
The Cavity. — The cavity of the true pelvis is bounded in front by the symphysis
pubis; behind, by the concavity of the sacrum and coccyx, which, curving forward
above and below, contracts the inlet and outlet of the canal; and laterally it is
bounded by a broad, smooth, quadrangular surface of bone, corresponding to the
inner surface of the body of the ischium and that part of the ilium which is below
the ilio-pectineal line. The cavity is shallow in front, measuring at the symphy-
sis an inch and a half in depth, three inches and a half in the middle, and four
inches and a half posteriorly. From this description it will be seen that the cavity
of the pelvis is a short, curved canal, considerably deeper on its posterior than
on its anterior wall. This cavity contains, in the recent subject, the rectum,
bladder, and part of the organs of generation. The rectum is placed at the back
THE PELVIS
211
of the pelvis, and corresponds to the curve of the sacro-coccygeal column; the
bladder in front, behind the symphysis pubis. In the female the uterus and
vagina occupy the interval between these viscera.
The Lower Circumference or Outlet (apertura pelvis inferior). — The lower cir-
cumference of the pelvis is very irregular, and forms what is called the outlet.
It is bounded by three prominent eminences: one posterior, formed by the point
of the coccyx; and one on each side, the tuberosities of the ischia. These emi-
nences are separated by three notches ; one in front, the pubic arch (arcus pvbis) ,
formed by the convergence of the rami of the ischia and pubic bones on each
side. The other notches, one on each side, are formed by the sacrum and coccyx
behind, the ischium in front, and the ilium above; they are called the sacro-sciatic
notches ; in the natural state they are converted into foramina by the lesser and
greater sacro-sciatic ligaments. In the recent state, when the ligaments are in
situ, the outlet of the pelvis is lozenge-shaped, bounded in front by the subpubic
ligament and the rami of the os pubis and ischium; on each side by the tuber-
osities of the ischia; and behind by the great sacro-sciatic ligaments and the tip
of the coccyx.
The diameters of the outlet of the pelvis are two, antero-posterior and trans-
verse. The antero-posterior (conjugate] diameter (diameter recta of the outlet)
extends from the tip of the coccyx to the lower part of the symphysis pubis; its
average measurement is three and three-quarter inches in the male and four and
one-half inches in the female. The antero-posterior diameter varies with the
length of the coccyx, and is capable of increase or diminution on account of the
mobility of that bone. During labor the coccyx may be bent back so that the
conjugate is increased one inch, or even one and one-fourth inches. The trans-
verse diameter extends from the posterior part of one ischiatic tuberosity to the
same point on the opposite side: the average measurement is three and a half
inches in the male and four and three-fourths in the female.1
Oblique diameters are not employed, as there are no fixed points from which
to measure them.
Position of the Pelvis. — In the erect posture the pelvis is placed obliquely with
regard to the trunk of the body: the bony ring, which forms the brim of the true
pelvis, is placed so as to form an angle of about 60 to 65 degrees with the ground
on which we stand (inclinatio pelvis). The pelvic surface of the symphysis pubis
looks upward and backward, the concavity of the sacrum and coccyx downward
and forward, the base of the sacrum in well-formed female bodies being nearly
four inches above the upper border of the symphysis pubis, and the apex of the
coccyx a little more than half an inch above its lower border. In consequence
of the obliquity of the pelvis the line of gravity of the head, which passes through
the middle of the odontoid process of the axis and through the points of junc-
tion of the curves of the vertebral column to the sacro-vertebral angle, descends
toward the front of the cavity, so that it bisects a line drawn transversely through
the middle of the heads of the thigh bones. And thus the centre of gravity of
the head is placed immediately over the heads of the thigh bones on which the
trunk is supported.
Axes of the Pelvis (Fig. .156) . — The plane of the inlet of the true pelvis will
be represented by a line drawn from the base of the sacrum to the upper margin
1 The measurements of the pelvis given above are, I believe, fairly accurate, but different measurements are
tfiven by various authors, no doubt due in a great measure to differences in the physique and stature of the
population from whom the measurements have been taken. The accompanying chart has been formulated to
show the measurements of the pelvis which are adopted by many obstetricians. — ED.
Of inlet
Of outlet
DIAMETERS OF THE TRUE PELVIS IN WOMAJJ.
Antero-posterior. Oblique. Transverse.
43/s inches (118 mm.) 5 inches (127 mm.) 5% inches (135 mm.)
4% inches (115 mm. ) 4% inches (120 mm.}
212
THE SKELETON
of the symphysis pubis. A line carried at right angles with this at its middle
would correspond at one extremity with the umbilicus, and at the other with the
middle of the coccyx: the axis of the inlet is therefore directed downward and
backward. The axis of the outlet, prolonged upward, would touch the base of
the sacrum, and is therefore directed downward
and forward. The axis of the cavity is curved
like the cavity itself; this curve corresponds to
the concavity of the sacrum and coccyx, the
extremities being indicated by the central points
of the inlet and outlet. A knowledge of the
direction of these axes serves to explain the
course of the foetus in the passage through the
pelvis during parturition. It is also important
to the surgeon, as indicating the direction of
the force required in the removal of calculi from
the bladder by the sub-pubic operation, and as
determining the direction in which instruments
should be used in operations upon the pelvic
viscera.
Differences between the Male and the
Female Pelvis. — The female pelvis, looked at
as a whole, is distinguished from the male by
the bones being more delicate, by its width
being greater and its depth smaller. The whole
pelvis is less massive, and its bones are lighter and more slender, and its muscu-
lar impressions are slightly marked. The iliac fossa? are shallow, and the anterior
iliac spines widely separated; hence the greater prominence of the hips. The
inlet in the female is larger than in the male; it is more nearly circular, and the
Plane o.
FIG. 156. — Vertical section of the pelvis,
with lines indicating the axis of the pelvis.
FIG. 157. — Diameters of the pelvic inlet.
sacro- vertebral angle projects less forward. The cavity is shallower and wider;
the sacrum is shorter, wider, and less curved; the obturator foramina are tri-
angular, and smaller in size than in the male. The outlet is larger and the
coccyx more movable. The spines of the ischia project less inward. The tuber-
THE OS INNOMINATUM
213
cities of the ischia and the acetabula are wider apart. The pubic arch is wider
and more rounded than in the male, where it is an angle rather than an arch.
En consequence of this the width of the fore part of the pelvic outlet is much in-
creased and the passage of the foetal head facilitated.
The size of the pelvis varies not only in the two sexes, but also in different
aembers of the same sex. This does not appear to be influenced in any way by
FIG. 158.— Diameters of the pelvic outlet.
the height of the individual. Women of short stature, as a rule, have broad pelves.
)ccasionally the pelvis is equally contracted in all its dimensions, so much so that
ill its diameters measure an inch less than the average, and this even in women
)f average height and otherwise well formed. The principal divergences, however,
ire found at the inlet, and affect the relation of the antero-posterior to the trans-
verse diameter. Thus we may have a pelvis the inlet of which is elliptical either
in a transverse or antero-posterior direction; the transverse diameter in the former
ind the antero-posterior in the latter greatly exceeding the other diameters. Again,
le inlet of the pelvis in some instances is seen to be almost circular. The same
lifferences are found in various races. European women are said to have the
lost roomy pelves. That of the negress is smaller, circular in shape, and with a
larrow pubic arch. The Hottentots and Bushwomen possess the smallest pelves.
In the foetus and for several years after birth the pelvis is small in proportion
that of the adult. The cavity is deep, and the projection of the sacro-vertebral
ingle less marked. The generally accepted opinion that the female pelvis does
lot acquire its sexual characters until after puberty has been shown by recent
observations1 to be erroneous, the characteristic differences between the male and
female pelvis being distinctly indicated as early as the fourth month of fcetal life.
At birth these differences are distinct (Romiti), the female pelvis possessing less
straight ilia, a broader subpubic arch, and less height than the male.
The Os Innominatum, called also Os Coxae, Hip Bone, Haunch Bone,
the Nameless Bone (Figs. 159, 160).
The os innominatum (in, not; nomino, I name) is so called from bearing no
resemblance to any known object. It is a large, irregularly shaped, flat bone,
constricted in the centre and expanded above and below. With its fellow of the
1 Fehling, Zeitschr. fur Geburt. u. Gynaek., Bd. ix. und x.; and Arthur Thomson, Journal of Anatomy and
Physiology, vol. xxxiii.
214
THE SKELETON
opposite side it forms the sides and anterior wall of the pelvic cavity. In young
subjects it consists of three separate parts, which meet and form the large, cup-
like cavity, the acetabulum, situated near the middle of the outer surface of the
bone; and, although in the adult these have become united, it is usual to describe
the bone as divisible into three portions — the ilium, the ischium, and the pubis.
nterior superior
spine.
Ilio-pectineal line
for Gimbernat's LIGAMENT.
OEMELLUS SUPERIOR.
/Spine of ischium.
QEMELLUS INFERIOR
*^LxRECTUS ABOOMINIS.
DDUCTOR LONQUS.
FIG. 159. — Right os innominatum. External surface.
The ilium, so called from its supporting the flank (ilium or ileum, the flank),
is the superior, broad, and expanded portion which runs upward from the
acetabulum and forms the prominence of the hip.
The ischium (iayiov, the hip) is the inferior and strongest portion of the bone;
it proceeds downward from the acetabulum, expands into a large tuberosity, and
then, curving forward, forms, with the descending ram us of the os pubis, a large
aperture, the obturator foramen.
THE OS INNOMINATUM
215
The os pubis is that portion which extends inward and downward from the
?etabulum to articulate in the middle line with the bone of the opposite side: it
forms the front of the pelvis, supports the external organs of generation, and has
?ived its name from the skin over it being covered with hair (pubes).
COMPRESSOR URETHR/C./
TRANSVERSUS PERINEI.
ERECTOR PENIS.
Crus penis.
FIG. 160. — Right os innominatum. Internal surface.
The Hium (os ilium). — The lower or constricted part of the ilium is thick,
though narrower than the expanded portion. It aids in the formation of the
Jtabulum and is called the body (corpus ossis ilium). The broad expanded
>rtion of the ilium is thin in many places. It is called the ala (ala ossis ilium) .
lie ilium presents for examination two surfaces, an external and an internal; a
?rest, and two borders, an anterior and a posterior.
External Surface or Dorsum of the Ilium (Fig. 159). — The posterior part of this
surface is directed backward and outward; its front part, downward and outward.
It is smooth, convex in front, deeply concave behind ; bounded above by the crest,
216 THE SKELETON
below by the upper border of the acetabulum; in front and behind by the anterior
and posterior borders. This surface is crossed in an arched direction by three
semicircular lines — the superior, middle, and inferior curved lines. The superior
curved line, or the posterior gluteal line (linea glutcea posterior), the shortest of the
three, commences at the crest, about two inches in front of its posterior extremity;
it is at first distinctly marked, but as it passes downward and backward to the
upper part of the great sacro-sciatic notch, where it terminates, it becomes less
marked, and is often altogether lost. Behind this line is a narrow semilunar
surface, the upper part of which is rough and affords attachment to part of
the Gluteus maximus; the lower part is smooth and has no muscular fibres
attached to it. The middle curved line, or the anterior gluteal line (linea glutcea
anterior), the longest of the three, commences at the crest, about an inch
behind its anterior extremity, and, taking a curved direction downward and
backward, terminates at the upper part of the great sacro-sciatic notch. The
space between the superior and middle curved lines and the crest is concave,
and affords attachment to the Gluteus medius muscle. Near the central part
of this line may often be observed the orifice of a nutrient foramen. The inferior
curved or inferior gluteal line (linea glutcea inferior}, the least distinct of the three,
commences in front at the notch on the anterior border, and, taking a curved
direction backward and downward, terminates at the middle of the great sacro-
sciatic notch. The surface of bone included between the middle and inferior
curved lines is concave from above downward, convex from before backward, and
affords attachment to the Gluteus minimus muscle. Beneath the inferior curved
line, and corresponding to the upper part of the acetabulum, is a roughened sur-
face (sometimes a depression), to which is attached the reflected tendon of the
Rectus femoris muscle.
Internal Surface. — The internal surface (Fig. 160) of the ilium is bounded above
by the crest; below it is continuous with the pelvic surface of the os pubis and
ischium, a faint line only indicating the place of union; and before and behind it
is bounded by the anterior and posterior borders. It presents a large, smooth,
concave surface, called the iliac fossa, or venter ilii (fossa iliaca) , which lodges the
Iliacus muscle, and presents at its lower part the orifice of a nutrient canal (fora-
men nutricium) ; and below this a smooth, rounded border, the ilio-pectineal line
or the linea ilio-pectinea (linea arcuata) , which separates the iliac fossa from that
portion of the internal surface which enters into the formation of the true pelvis,
and which gives attachment to part of the Obturator internus muscle. Behind
the iliac fossa is a rough surface divided into two portions, an anterior and
a posterior. The anterior or auricular surface (fades auricularis) , so called from
its resemblance in shape to the ear, is coated with cartilage in the recent state,
and articulates with a surface of similar shape on the side of the sacrum. The
posterior portion (tuberositas iliaca) is rough, for the attachment of the posterior
sacro-iliac ligaments and for a part of the origin of the Erector and Multifidus
spinse. In many bones a furrow exists in front, under and behind the auricular
surface. This furrow is the paraglenoid sulcus (sulcus paraglenoidalis) , and it
affords attachment to the sacro-sciatic ligaments.
The Crest of the Ilium (crista iliaca). — The crest of the ilium is convex in its
general outline and sinuously curved, being concave inward in front, concave
outward behind. It is longer in the female than in the male, very thick behind,
and thinner at the centre than at the extremities. It terminates at either end in
a prominent eminence, the anterior superior and posterior superior spinous process
(spina iliaca anterior superior et spina iliaca posterior superior) . The surface of
the crest is broad, and divided into an external lip (labium externum), an inter-
nal lip (labium internum), and an intermediate space (linea intermedia). About
two inches behind the anterior superior spinous process there is a prominent
THE OS INNOMINATUM 217
tul>ercle on the outer lip. To the external lip is attached the Tensor fasciae
femoris, Obliquus externus abdominis, and Latissimus dorsi, and along its
ole length, the fascia lata; to the space between the lips, the Internal oblique;
the internal lip, the Transversalis, Quadratus lumborum, and Erector spinse,
the Iliacus, and the fascia iliaca.
Anterior Border. — The anterior border of the ilium is concave. It presents two
>rojections, separated by a notch. Of these, the uppermost, situated at the junc-
tion of the crest and anterior border, is called the anterior superior spinous process
>f the ilium (spina iliaca anterior superior), the outer border of which gives
ittachment to the fascia lata and the origin of the Tensor fasciae femoris (tensor
iginas femoris}; its inner border, to the Iliacus; while its extremity affords attach-
lent to Poupart's ligament and the origin of the Sartorius. Beneath this emi-
icnce is a notch which gives attachment to the Sartorius muscle, and across
fhich passes the external cutaneous nerve. Below the notch is the anterior
iferior spinous process (spina iliaca anterior inferior}, which terminates in the
ipper lip of the acetabulum; it gives attachment to the straight tendon of
the Rectus femoris muscle and the ilio-femoral ligament. On the inner side of the
interior inferior spinous process is a broad, shallow groove, over which passes
ic Ilio-psoas muscle. This groove is bounded internally by an eminence, the
lio-pectineal eminence (eminentia iliopectinea) , which marks the point of union
)f the ilium and os pubis.
Posterior Border. — The posterior border of the ilium, shorter than the anterior,
ilso presents two projections separated by a notch, the posterior superior spinous
rocess (spina iliaca posterior superior) and the posterior inferior spinous process
(spina iliaca posterior inferior). The former corresponds with that portion of
le inner surface of the ilium which serves for the attachment of the oblique
>rtion of the sacro-iliac ligaments and the Multifidus spinse muscle ; the latter,
the auricular portion which articulates with the sacrum. Below the pos-
srior inferior spinous process is a deep notch, the great sciatic, ilio-sciatic, or
the great sacro-sciatic notch (incisura ischiadica major).
The Ischium (os ischii). — The ischium forms the lower and back part of the
)s innominatum. It is divisible into a thick and solid portion — the body; a large,
>ugh eminence, on which the trunk rests in sitting — the tuberosity; and a thin
>art which passes forward and slightly upward — the ramus.
The Body (corpus ossis ischii). — The body, somewhat triangular in form, pre-
ints three surfaces, external, internal, and posterior; and three borders, external,
iternal, and posterior. The external surface corresponds to that portion of the
?etabulum formed .by the ischium; it is smooth and concave, and forms a
little more than two-fifths of the acetabular cavity; its outer margin is bounded
:>y a prominent rim or lip, the external border, to which the cotyloid fibro-
?artilage is attached. Below the acetabulum, between it and the tuberosity, is
a deep groove, along which the tendon of the Obturator externus muscle runs
as it passes outward to be inserted into the digital fossa of the femur. The
internal surface is smooth, concave, and enters into the formation of the lateral
boundary of the true pelvic cavity. This surface is perforated by two or three
large, vascular foramina, and affords attachment to part of the Obturator inter-
mis muscle. The posterior surface is quadrilateral in form, broad and smooth.
Below, where it joins the tuberosity, it presents a groove, the obturator groove
(sulcus obturatorius) , continuous with that on the external surface, for the tendon
of the Obturator externus muscle. The lower edge of this groove is formed by
the tuberosity of the ischium, and affords attachment to the Gemellus inferior
muscle. This surface is limited, externally, by the margin of the acetabulum;
behind, by the posterior border; it supports the Pyriformis, the two Gemelli, and
the Obturator internus muscles in their passage outward to the great trochanter.
218 THE SKELETON
The external border forms the prominent rim of the acetabulum, and separates
the posterior from the external surface. To it is attached the cotyloid fibro-
cartilage. The internal border is thin, and forms the outer circumference of the
obturator foramen. The posterior border of the body of the ischium presents, a
little below the centre, a thin and pointed, triangular eminence, the spine of the
ischium (spina ischiadica), more or less elongated in different subjects; its exter-
nal surface gives attachment to the Gemellus superior, its internal surface to
the Coccygeus and Levator ani; whilst to the pointed extremity is connected the
lesser sacro-sciatic ligament. Above the spine is a notch of large size, the great
sacro-sciatic notch (incisura ischiadica major), converted into a foramen, the great
sacro-sciatic foramen (foramen ischiadicum majus) , by the lesser sacro-sciatic liga-
ment; it transmits the Pyriformis muscle, the gluteal vessels, and superior and
inferior gluteal nerves; the sciatic vessels, the greater and lesser sciatic nerves,
the internal pudic vessels and nerve, and the nerves to the Obturator internus and
Quadratus femoris. Of these, the gluteal vessels and superior gluteal nerve pass
out above the Pyriformis muscle, the other structures, below it. Below the spine
is a smaller notch, the lesser sacro-sciatic notch (incisura ischiadica minor) ; it is
smooth, coated in the recent state with cartilage, the surface of which presents
two or three ridges corresponding to the subdivisions of the tendon of the Obtu-
rator internus, which winds over it. It is converted into a foramen, the lesser
sacro-sciatic foramen (foramen ischiadicum minus), by the sacro-sciatic ligaments,
and transmits the tendon of the Obturator internus, the nerve which supplies
that muscle, and the internal pudic vessels and nerve.
The Tuberosity of the Ischium (tuber ischiadicum). — The tuberosity of the
ischium is the portion of bone between the body and the ascending ramus.
Some anatomists name this portion of bone the descending or superior ramus
(ramus superior ossis ischii), and restrict the term tuberosity to the surface of
the bone which is rough, and is directed backward and outward. The tuber-
osity presents for examination three surfaces: external, internal, and posterior.
The external surface is quadrilateral in shape, and rough for the attachment of
muscles. It is bounded above by the groove for the tendon of the Obturator
externus; in front it is limited by the posterior margin of the obturator foramen,
and below it is continuous with the ramus of the bone; behind, it is bounded by
a prominent margin which separates it from the posterior surface. In front of
this margin the surface gives attachment to the Quadratus femoris, and anterior
to this to some of the fibres of origin of the Obturator externus. The lower part
of the surface gives origin to part of the Adductor magnus. The internal sur-
face forms part of the bony wall of the true pelvis. In front it is limited by the
posterior margin of the obturator foramen. Behind, it is bounded by a sharp
ridge, for the attachment of a falciform prolongation of the great sacro-sciatic
ligament; it sometimes presents a groove on the inner side of this ridge for the
lodgement of the internal pudic vessels and nerve; and, more anteriorly, has
attached the Transversus perinsei . and Erector penis muscles. The posterior
surface is divided into two portions — a lower rough, somewhat triangular part,
and an upper smooth, quadrilateral portion. The anterior portion is subdivided
by a prominent vertical ridge, passing from base to apex, into two parts; the
outer one gives attachment to the Adductor magnus; the inner to the great sacro-
sciatic ligament. The upper portion is subdivided into two facets by an oblique
ridge which runs downward and outward; from the upper and outer facet arises
the Semimembranosus; from the lower and inner, the Biceps and Semitendinosus.
The Ramus or Inferior Ramus or Ascending Ramus of the Ischium (ramus inferior
ossis ischii). — The ramus is the thin, flattened part of the ischium which ascends
from the tuberosity upward and inward, and joins the descending ramus of the
os pubis, their point of junction being indicated in the adult by a rough line.
THE OS INNOMINATUM 219
outer surface of the ramus is rough, for the attachment of the Obturator
sxternus muscle, and also some fibres of the Adductor magnus; its inner sur-
face forms part of the anterior wall of the pelvis. Its inner border is thick,
)iigh, slightly everted, forms part of the outlet of the pelvis, and presents two
ridges and an intervening space. The ridges are continuous with similar ones
>n the descending ramus of the os pubis: to the outer one is attached the deep
iver of the superficial perineal fascia, and to the inner, the superficial layer of
the triangular ligament of the urethra. If these two ridges are traced downward,
icy will be found to join with each other just behind the point of origin of the
^ransversus perinrei muscle; here the two layers of fascia are continuous behind
ic posterior border of the muscle. To the intervening space, just in front of the
)int of junction of the ridges, is attached the Transversus perinaei muscle, and
front of this a portion of the crus penis vel clitoridis and the Erector penis vel
^litoridis muscle. Its outer border is thin and sharp, and forms part of the inner
largin of the obturator foramen.
The Pubis (os pubis) . — The os pubis forms the anterior part of the os innomi-
latum, and, with the bone of the opposite side, forms the front boundary of the
rue pelvic cavity. It is divisible into a body, a superior or ascending and an inferior
descending ramus.
The Body (corpus ossis pubis). — The body is the broad portion of bone formed
the junction of the two rami. It is somewhat quadrilateral in shape, and
>resents for examination two surfaces and three borders.' The anterior surface
rough, directed downward and outward, and serves for the attachment of
various muscles. To the upper and inner angle, immediately below the crest,
attached the Adductor longus ; lower down, from without inward, are attached
the Obturator externus, the Adductor brevis, and the upper part of the Gracilis.
he posterior surface, convex from above downward, concave from side to side,
smooth, and forms part of the anterior wall of the pelvis. It gives attach-
icnt to the Levator ani, Obturator internus, a few muscular fibres prolonged
)m the bladder, and the pubo-prostatic ligaments. The upper border presents
for examination a prominent tubercle, which projects forward and is called the
spine (tuberculum pubicum); to it are attached the outer pillar of the external
abdominal ring and Poupart's ligament. Passing upward and outward from
this is a prominent ridge, forming part of the ilio-pectineal line (linea arcuata),
and called the pecten ossis pubis. It marks the brim of the true pelvis: to it are
attached a portion of the conjoined tendon of the Internal oblique and Trans-
versalis muscles, Gimbernat's ligament, and the triangular fascia of the abdomen.
Internal to the spine of the os pubis is the crest, which extends from this process
to the inner extremity of the bone. It affords attachment, anteriorly, to the con-
joined tendon of the Internal oblique and Transversalis ; and posteriorly, to the
Rectus and Pyramidalis muscles. The point of junction of the crest with the
inner border of the bone (symphysis) is called the angle; to it, as well as to the
symphysis, is attached the internal pillar of the external abdominal ring. The
internal border is articular; it is oval, covered by eight or nine transverse ridges,
or a series of nipple-like processes arranged in rows, separated by grooves; they
serve for the attachment of a thin layer of cartilage, placed between it and the
central fibro-cartilage. The outer border presents a sharp margin, which forms
part of the circumference of the obturator foramen and affords attachment to
the obturator membrane.
The Ascending or Superior Ramus of the Pubis (ramus superior ossis pubis). —
The ascending or superior ramus extends from the body to the point of junction
of the os pubis with the ilium, and forms the upper part of the circumference of
the obturator foramen. It presents for examination a superior, inferior, and
posterior surface, and an outer extremity. The superior surface presents a con-
220 1HE SKELETON
tinuation of the ilio-pectineal line, already mentioned as commencing at the
pubic spine. In front of this ridge the surface of bone is triangular in form,
wider externally than internally, smooth, and is covered by the Pectineus muscle.
The surface is bounded externally by a rough eminence, the ilio-pectineal emi-
nence (eminentia iliopectinea) , which serves to indicate the point of junction of
the ilium and os pubis, and gives attachment to the Psoas parvus, when this
muscle is present. The triangular surface is bounded below by a prominent
ridge, the obturator crest (crista obturatoria) , which extends from the cotyloid
notch to the spine of the os pubis. The inferior surface forms the upper bound-
ary of the obturator foramen, and presents externally a broad and deep oblique
groove, the obturator groove (sulcus obturatorius) , for the passage of the obturator
vessels and nerve; and internally a sharp margin which forms part of the cir-
cumference of the obturator foramen, and to which the obturator membrane is
attached. The posterior surface forms part of the anterior boundary of the true
pelvis. It is smooth, convex from above downward, and affords attachment to
some fibres of the Obturator internus. The outer extremity, the thickest part of
the ramus, forms one-fifth of the cavity of the acetabulum.
The Descending or Inferior Ramus of the Pubis (ramus inferior ossis pubis). —
The descending or inferior ramus of the os pubis is thin and flattened. It passes
outward and downward, becoming narrower as it descends, and joins with the
ramus of the ischium. Its anterior surface is rough, for the attachment of muscles
— the Gracilis along its inner border; a portion of the Obturator externus where it
enters into the formation of the foramen of that name; and between these two
muscles the- Adductores brevis and magnus from within outward. The posterior
surface is smooth, and gives attachment to the Obturator internus, and, close to
the inner margin, to the Compressor urethrse. The inner border is thick, rough,
and everted, especially in females. It presents two ridges, separated by an inter-
vening space. The ridges extend downward, and are continuous with similar
ridges on the ascending ramus of the ischium; to the external one is attached
the deep layer of the superficial perineal fascia, and to the internal one the super-
ficial layer of the triangular ligament of the urethra. The outer border is thin
and sharp, forms part of the circumference of the obturator foramen, and gives
attachment to the obturator membrane.
The Cotyloid Cavity or Acetabulum. — The cotyloid cavity, or acetabulum, is
a deep, cup-shaped, hemispherical depression, directed downward, outward, and
forward; formed internally by the os pubis, above by the ilium, behind and below
by the ischium, a little less than two-fifths being formed by the ilium, a little more
than two-fifths by the ischium, and the remaining fifth by the pubic bone. It is
bounded by a prominent, uneven rim, which is thick and strong above, and serves
for the attachment of the cotyloid ligament, which contracts its orifice and deepens
the surface for articulation. It presents below a deep notch, the cotyloid notch
(incisura acetabuli), which is continuous with a circular depression, the fossa of
the acetabulum (fossa acetabuli), at the bottom of the cavity: this depression is
perforated by numerous apertures, lodges a mass of fat, and its margins, as well
as those of the notch, serve for the attachment of the ligamentum teres. In front,
above and behind the fossa acetabuli, is a concave rim of bone (fades lunata) . The
cotyloid notch is converted, in the natural state, into a foramen by a dense liga-
mentous band which passes across it. Through this foramen the nutrient vessels
and nerves enter the joint.
The Obturator or Thyroid Foramen (foramen obturatum). — The obturator or
thyroid foramen is a large aperture situated between the ischium and os pubis.
In the male it is large, of an oval form, its longest diameter being obliquely from
before backward ; in the female it is smaller and more triangular. It is bounded
by a thin, uneven margin, to which a strong membrane is attached, and presents,
THE OS INNOMINATUM
221
anteriorly, a deep groove, the obturator groove (sulcus obturatorius) , which runs
from the pelvis obliquely inward and downward. This groove is converted into
foramen by the obturator membrane, and transmits the obturator vessels and
lerve.
Structure. — This bone consists of much cancellous tissue, especially where it
thick, enclosed between two layers of dense, compact tissue. In the thinner
>arts of the bone, as at the bottom of the acetabulum and centre of the iliac
fossa, it is usually semitransparent, and composed entirely of compact tissue.
Development (Fig. 161). — By eight centres: three primary — one for the ilium,
me for the ischium, and one for the os pubis; and five secondary — one for the
Three primary (Ilium, Ischium, and Os Pubis).
^^ secondary
"^
8. Symphysis pubis.
The three primary centres unite through a \-shaped piece about puberty.
Epiphyses appear about puberty, and unite about the twenty-fifth year.
FIG. 161. — Plan of the development of the os innominatum.
st of the ilium, one for the anterior inferior spinous process (said to occur more
frequently in the male than in the female), one for the tuberosity of the ischium,
>ne for the symphysis pubis (more frequent in the female than the male), and one
3r more for the Y-shaped piece at the bottom of the acetabulum. These various
centres appear in the following order: First, in the ilium, at ihe lower part of
the bone, immediately above the sciatic notch, at about the eighth or ninth week;
secondly, in the body of the ischium, at about the third month of foetal life;
thirdly, in the body of the os pubis, between the fourth and fifth months. At
birth the three primary centres are quite separate, the crest, the bottom of the
acetabulum, the ischial tuberosity, and the rami of the ischium and pubes being
still cartilaginous. At about the seventh or eighth year the rami of the os pubis
and ischium are almost completely united by bone. About the thirteenth or
fourteenth year the three divisions of the bone have extended their growth into
the bottom of the acetabulum, being separated from each oth^r by a Y-shaped
portion of cartilage, which now presents traces of ossification, often by two or
222 THE SKELETON
more centres. One of these, the os acetabuli, appears about the age of twelve,
between the ilium and os pubis, and fuses with them about the age of eighteen.
It forms the pubic part of the acetabulum. The ilium and ischium then become
joined, and lastly the os pubis to the ischium, through the intervention of this
Y-shaped portion. At about the age of puberty ossification takes place in each
of the remaining portions, and they become joined to the rest of the bone
between the twentieth and twenty-fifth years. Separate centres are frequently
found for the pubic and ischial spines
Articulations. — With its fellow of the opposite side, the sacrum, and femur.
Attachment of Muscles. — To the ilium, sixteen. To the outer lip of the crest,
the Tensor vaginje femoris, Obliquus externus abdominis, and Latissiinus dorsi;
to the internal lip, the Iliacus, Transversalis, Quadratus lumborum, and Erector
spinse; to the interspace between the lips, the Obliquus interims. To the outer
surface of the ilium, the Gluteus maximus, Gluteus medius, Glutens minimus,
reflected tendon of the Rectus; to the upper part of the great sacro-sciatic notch, a
portion of the Pyriformis; to the internal surface, the Iliacus; to that portion of
the internal surface below the linea ilio-pectinea, the Obturator internus to the
internal surface of the posterior superior spine, and the Multifidus spinse; to the
anterior border, the Sartorius and straight tendon of the Rectus. To the ischium,
thirteen. To the outer surface of the ramus, the Obturator externus and Adductor
magnus; to the internal surface, the- Obturator internus and Erector penis. To the
spine, the Gemellus superior, Levator ani, and Coccygeus. To the tuberosity, the
Biceps, Semitendinosus, Semimembranosus, Quadratus femoris, Adductor mag-
nus, Gemellus inferior, Transversus perinnei, Erector penis. To the pubis,
sixteen: Obliquus externus, Obliquus internus, Transversalis, Rectus, Pyramid-
alis, Psoas parvus, Pectineus, Adductor magnus, Adductor longus, Adductor
brevis, Gracilis, Obturator externus and internus, Levator ani, Compressor
urethne, and occasionally a few fibres of the Accelerator urinse.
Surface Form. — The pelvic bones are so thickly covered with muscles that it is only at
certain points that they approach the surface and can be felt through the skin. In front,
the anterior superior spinous process is easily recognized; a portion of it is subcutaneous,
and in thin subjects may be seen to stand out as a prominence at the outer extremity of the fold
of the groin. In fat subjects its position is marked by an oblique depression amongst the sur-
rounding fat, at the bottom of which the bony process may be felt. Proceeding upward and
outward from this process, the crest of the ilium may be traced throughout its whole length,
sinuously curved. It is represented, in muscular subjects, on the surface, by a groove or fur-
row, the iliac furrow, caused by the projection of fleshy fibres of the External oblique muscles
of the abdomen; the iliac furrow lies slightly below the level of the crest. It terminates behind
in the posterior superior spinous process, the position of which is indicated by a slight depression
on a level with the spinous process of the second sacral vertebra. Between the two posterior
superior spinous processes, but at a lower level, is to be felt the spinous process of the third
sacral vertebra (see page 69). Another part of the bony pelvis easily accessible to touch is the
tuberosity of the ischium, situated beneath the gluteal fold, and, when the hip is flexed, it is
easily felt, as it is then to a great extent uncovered by muscle. Finally, the spine of the os
pubis can always be readily felt, and constitutes an important surgical guide, especially in con-
nection with the subject of hernia. It is nearly in the same horizontal line with the upper edge
of the great trochanter. In thin subjects it is very apparent, but in the obese it is obscured by
the pubic fat. It can, however, be detected by following up the tendon of origin of the
Adductor longus muscle.
Surgical Anatomy. — There is arrest of development in the bones of the pelvis in cases
of extroversion of the bladder ; the anterior part of the pelvic girdle being deficient, the bodies
of the pubic bones imperfectly developed, and the symphysis absent. The pubic bones are
separated to the extent of from two to four inches, the superior rami shortened and directed
forward, and the obturator foramen diminished in size, narrowed, and turned outward. The
iliac bones are straightened out more than normal. The sacrum is very peculiar. The lateral
curve, instead of being concave, is flattened out or even convex, with the ilio-sacral facets turned
more outward than normal, while the vertical curve is straightened.1
i Wood. Heath's Dictionary of Practical Surgery, i., 426. — ED. of 15th English Edition.
THE FEMUR, OR THIGH BONE 223
Fractures of the pclvix are divided into fractures of the false pelvis and of the true pelvis,
.ctures of the false pelvis vary in extent: a small portion of the iliac crest may be broken or
ie of the spinous processes may be torn off, and this may be the result of muscular action ; or
ie bone may be extensively comminuted. This latter accident is the result of some crushing
violence, and may be complicated with fracture of the true pelvis. These cases may be accom-
panied by injury to the intestine as it lies in the hollow of the bone, or to the iliac vessels as
they course along the margin of the true pelvis. Fractures of the true pelvis generally occur
through the ascending ramus of the os pubis and the ramus of the ischium, as this is the weakest
part of the bony ring, and may be caused either by crushing violence applied in an antero-
posterior direction, when the fracture occurs from direct force, or by compression laterally,
when the acetabula are pressed together, and the bone gives way in the same place from indirect
violence. Occasionally the injury may be double, a break occurring on both sides of the body.
In fracture of the true pelvis the contained viscera are liable to be damaged: the small intestines,
the urethra, the bladder, the rectum, the vagina, and even the uterus, in the female, have all
been lacerated by a displaced fragment. Fractures of the acetabulum are occasionally met with:
either a portion of the rim may be broken off, or a fracture may take place through the bottom
of the cavity, and the head of the femur may be driven inward and project into the pelvic cavity.
Separation of the Y-shaped cartilage at the bottom of the acetabulum may also occur in the
young subject, dispersing the bone into its three anatomical portions.
The sacrum is seldom broken. The cause is direct violence — i. e., blows, kicks, or falls
on the part. The lesion may be complicated with injury to the nerves of the sacral plexus,
leading to paralysis and loss of sensation in the lower extremity or to incontinence of faeces from
paralysis of the Sphincter ani.
Fracture of the coccyx is a very rare injury, but does occasionally take place. Some sup-
posed dislocations of this bone have been fractures and so have some of the cures diagnosti-
cated as coccygodynia. A fracture of the coccyx is diie to direct force.
The pelvic bones often undergo important deformity in rickets, the effect of which in the
adult woman may interfere seriously with childbearing. The deformity is due mainly to the
weight of the spine and trunk, which presses on the sacro-vertebral angle and greatly increases
it, so that the antero-posterior diameter of the pelvis is diminished. But, in addition to this,
the weight of the viscera on the venter ilii causes those bones to expand and the tuberosities of
the ischia to incurve. In osteomalacia also great deformity may occur. The weight of the
trunk causes an increase in the sacro-vertebral angle and a lessening of the antero-posterior
diameter of the inlet, and at the same time the pressure of the acetabula on the heads of the
thigh-bones causes these cavities, with the adjacent bone, to be pushed upward and backward,
so that the oblique diameters of the pelvis are also diminished, and the cavity of the pelvis
assumes a triradiate shape, with the symphysis pubis pushed forward.
THE THIGH.
The thigh is that portion of the lower extremity which is situated between the
pelvis and the knee. It consists in the skeleton of a single bone, the femur.
The Femur, or Thigh Bone (Figs. 162, 163).
The femur (femur, the thigh) is the longest,1 largest, and strongest bone in the
skeleton, and almost perfectly cylindrical throughout the greater part of its extent.
In the erect posture it is not vertical, being separated from its fellow above by
a considerable interval, which corresponds to the entire breadth of the pelvis, but
inclining gradually downward and inward, so as to approach its fellow toward
its lower part, for the purpose of bringing the knee-joint near the line of gravity
of the body. The degree of this inclination varies in different persons, and
is greater in the female than the male, on account of the greater breadth of
the pelvis. The femur, like other long bones, is divisible into a shaft and two
extremities.
Upper Extremity. — The upper extremity presents for examination a head,
a neck, and a great and lesser trochanters.
Head of the Femur (caput femoris). — The head, which is globular, and
forms rather more than a hemisphere, is directed upward, inward, and a little
J In a man six feet high it measures eighteen inches — one-fourth of the whole body. — ED. of 15th English
Edition.
224
THE SKELETON
OBTURATOR INTERNUS
and GEMELLI.
PYRIFORMIS.
.Shaft
a
SUB-CRUREUS.
•N*.
*NS
Wjtftit. **>
FIG. 162. — Right femur. Anterior surface.
forward, the greater part of its
convexity being above and in front.
£ Its surface is smooth, coated with
cartilage in the recent state, ex-
cept at a little behind and below its centre,
where is an ovoid depression (fovea capitis
femoris), for the attachment for the Ligamen-
turn teres.
The Neck of the Femur (collum femoris) . — The
neck is a flattened pyramidal process of bone
which connects the head with the shaft. It
varies in length and obliquity at various periods
in life and under different circumstances. The
angle is widest in infancy, and becomes lessened
during growth, so that at puberty it forms a
gentle curve from the axis of the shaft. In the
adult it forms an angle of about 1 30 degrees
with the shaft, but varies in inverse proportion
to the development of the pelvis and the stature.
In consequence of the prominence of the hips
and widening of the pelvis in the female, the
neck of the thigh bone forms more nearly a right
angle with the shaft than it does in man. It has
been stated that the angle diminishes in old age
and the direction of the neck becomes hori-
zontal, but this statement is founded on insuffi-
cient evidence. Sir George Humphry states
that the angle decreases during the period of
growth, but after full growth has been attained
it does not usually undergo any change, even
in old age. He further states that the angle
varies considerably in different persons of the
same age. It is smaller in short than in long
bones, and when the pelvis is wide.1 The neck
is flattened from before backward, contracted in
the middle, and broader at its outer extremity,
where it is connected with the shaft, than at
its summit, where it is attached to the head.
The vertical diameter of the outer half is in-
creased by the thickening of the lower edge,
which slopes downward to join the shaft at the
lesser trochanter, so that the outer half of the
neck is flattened from before backward, and its
vertical diameter measures one-third more than
the antero-posterior. The inner half is smaller
and of a more circular shape. The anterior
surface of the neck is perforated by numerous
vascular foramina. The posterior surface is
smooth, and is broader and more concave than
the anterior; it gives attachment to the posterior
part of the capsular ligament of the hip-joint,
about half an inch above the posterior intertro-
chanteric line. The superior border is short and
1 Journal of Anatomy and Physiology.
THE FEMUR, OR THIGH BONE 225
lick, and terminates externally at the great trochanter; its surface is perforated
y large foramina. The inferior border, long and narrow, curves a little back-
ward, to terminate at the lesser trochanter.
The Trochanters. — The trochanters (Tpo%d&, to run or roll) are prominent pro-
ssses of bone which afford leverage to the muscles which rotate the thigh on its
axis. They are two in number, the greater and the lesser.
The great trochanter (trochanter major) is a large, irregular, quadrilateral eminence,
situated at the outer side of the neck, at its junction with the upper part of the shaft.
It is directed a little outward and backward, and in the adult is about three-quarters
of an inch lower than the head. It presents for examination two surfaces and four
borders. The external surface, quadrilateral in form, is broad, rough, convex, and
marked by a prominent diagonal impression, which extends from the posterior
superior to the anterior inferior angle, and serves for the attachment of the tendon
of the Gluteus medius. Above the impression is a triangular surface, sometimes
rough for part of the tendon of the same muscle, sometimes smooth for the inter-
position of a bursa between that tendon and the bone. Below and behind the
diagonal line is a smooth, triangular surface, over which the tendon of the Gluteus
maximus muscle plays, a bursa being interposed. The internal surface is of much
less extent than the external, and presents at its base a deep depression, the digital
or trochanteric fossa (fossa trochant erica) , for the attachment of the tendon of the
Obturator externus muscle : above and in front of this an impression for the attach-
ment of the Obturator internus and Gemelli. The superior border is free; it is thick
and irregular, and marked near the centre by an impression for the attachment of
the Pyriformis. The inferior border corresponds to the point of junction of the base
of the trochanter with the outer surface of the shaft; it is marked by a rough, promi-
nent, slightly curved ridge, which gives attachment to the upper part of the Vastus
externus muscle. The anterior border is prominent, somewhat irregular, as well
as the surface of bone immediately below it; it affords attachment at its outer
part to the Gluteus minimus. The posterior border is very prominent, and appears
as a free, rounded edge, which forms the back part of the digital fossa.
The lesser trochanter (trochanter minor) is a conical eminence which varies in size
in different subjects; it projects from the lower and back parts of the base of the neck.
Its base is triangular, and connected with the adjacent parts of the bone by three
well-marked borders: two of these are above — the internal border, continuous with
the lower border of the neck, the external border with the posterior intertrochan-
teric line — while the inferior border is continuous with the middle division of the
linea aspera. Its summit, which is directed inward and backward, is rough, and
gives insertion to the tendon of the Ilio-psoas. The Iliacus is also inserted into
the shaft below the lesser trochanter between the Vastus internus in front and the
Pectineus behind.
A well-marked prominence of variable size, which projects from the upper and
front part of the neck at its junction with the great trochanter, is called the tuber-
cle of the femur; it is the point of meeting of five muscles: the Gluteus minimus
externally, the Vastus externus below, and the tendon of the Obturator internus
and Gemelli above. Running obliquely downward and inward from the tubercle
is the spiral line of the femur, or anterior intertrochanteric line (linea intertrochan-
terica) ; it winds round the inner side of the shaft, below the lesser trochanter, and
terminates in the linea aspera, about two inches below this eminence. Its upper
half is rough, and affords attachment to the ilio-femoral ligament of the hip-joint;
its lower half is less prominent, and gives attachment to the upper part of the
Vastus internus. Running obliquely downward and inward from the summit of
the great trochanter on the posterior surface of the neck is a very prominent,
well-marked ridge, the posterior intertrochanteric line (crista intertrochanterica}.
Its upper half forms the posterior border of the great trochanter, and its lower
15
226
THE SKELETON
Groove for tendon of
POPLITEUS.
%£
FIG. 163. — Right femur. Posterior surface.
half runs downward and inward
to the upper and back part of
the lesser trochanter. A slight
ridge sometimes commences about
the middle of the posterior inter-
trochanteric line, and passes ver-
tically downward for about two
inches along the back part of the
shaft: it is called the linea quadrati,
and gives attachment to the
Quadratus femoris and a few
fibres of the Adductor magnus
muscles.1
The Shaft of the Femur (corpus
femoris} . — The shaft, almost cylin-
drical in form, is a little broader
above than in the centre, and
somewhat flattened below, from
before backward. It is slightly
arched, so as to be convex in front
and concave behind, where it is
strengthened by a prominent lon-
gitudinal ridge, the linea aspera.
It presents for examination three
borders, separating three surfaces.
Of the three borders, one, the linea
aspera, is posterior; the other two
are placed laterally.
The Linea Aspera. — The linea
aspera (Fig. 163) is a prominent
longitudinal ridge or crest, on the
middle third of the bone, present-
ing an external lip (labium laterale) ,
an internal lip (labium mediale),
and a rough intermediate space.
Above, this crest is prolonged by
three ridges. The most external
ridge is very rough, and is con-
tinued almost vertically upward to
the base of the great trochanter.
It is sometimes termed the gluteal
ridge (tuberositas glutcea) , and gives
attachment to part of the Gluteus
maximus muscle ; its upper part is
sometimes elongated into a rough-
ened crest, on which is a more or
less well-marked, rounded tuber-
cle, a rudimental third trochanter
(trochanter tertius). The middle
ridge (linea pectinea) , the least dis-
1 Generally there is merely a slight thickening
about the centre of the intertrochanteric line,
marking the point of attachment of the Quad-
ratus femoris. This is termed by some anato-
mists the tubercle of the Quadratus. — ED. of
15th English Edition.
THE FEMUR, OR THIGH BONE 227
inct, is continued to the base of the trochanter minor, and the internal ridge is
)st above in the spiral line of the femur. Below, the linea aspera is prolonged
two ridges, which pass to the condyles and enclose between them a triangular
the popliteal surface (planum popliteum), upon which rests the popliteal
tery. Of these two ridges, the outer one is the more prominent, and descends
to the summit of the outer condyle. The inner one is less marked, especially at
its upper part, where it is crossed by the femoral artery. It terminates, below,
at the summit of the internal condyle, in a small tubercle, the adductor tubercle,
which affords attachment to the tendon of the Adductor magnus. To the inner
lip of the linea aspera and its inner prolongation above and below is attached
the Vastus interims, and to the outer lip and its outer prolongation above is
attached the Vastus externus. The Adductor magnus is attached to the linea
nsj>era, to its outer prolongation above and its inner prolongation below. Be-
tween the Vastus externus and the Adductor magnus are attached two muscles
— viz., the Gluteus maximus above, and the short head of the Biceps below.
Between the Adductor magnus and the Vastus interims four muscles are attached :
the Iliacus and Pectineus above, the Adductor brevis and Adductor longus below.
A little below the centre of the linea aspera is the nutrient foramen (foramen
nutricium), the orifice of the nutrient canal (canalis nutricius), which is directed
obliquely upward (proximally) .
Lateral Borders. — The two lateral borders of the femur are only slightly marked,
the outer one extending from the anterior inferior angle of the great trochanter
to the anterior extremity of the external condyle ; the inner one from the spiral line
at a point opposite the trochanter minor, to the anterior extremity of the internal
condyle. The internal border marks the limit of attachment of the Crureus muscle
internally.
Anterior Surface. — The anterior surface includes that portion of the shaft which
is situated between the two lateral borders. It is smooth, convex, broader above
and below than in the centre, slightly twisted, so that its upper part is directed
forward and a little outward, its lower part forward and a little inward. To the
upper three-fourths of this surface the Crureus is attached; the lower fourth is
separated from the muscle by the intervention of the synovial membrane of the
knee-joint and a bursa, and affords attachment to the Subcrureus to a small extent.
External Surface. — The external surface includes the portion of bone between
the external border and the outer lip of the linea aspera : it is continuous above
with the outer surface of the great trochanter, below with the outer surface of
the external condyle; to its upper three-fourths is attached the outer portion of
the Crureus muscle.
Internal Surface. — The internal surface includes the portion of bone between
the internal border and the inner lip of the linea aspera; it is continuous above
with the lower border of the neck, below with the inner side of the internal con-
dyle: it is covered by the Vastus internus muscle.
Lower Extremity. — The lower extremity, larger than the upper, is of a cuboid
form, flattened from before backward, and divided into two large eminences,
the condyles (condyli, from xovr7u/oc, a knuckle), by an interval which presents a
smooth depression in front called the trochlea (fades patellaris) , and a notch of con-
siderable size behind — the intercondyloid notch (fossa intercondyloidea). The exter-
nal condyle (condylus lateralis] is the more prominent anteriorly, and is the broader
both in the antero-posterior and transverse diameters. The internal condyle (con-
<l//lns medialis) is the narrower, longer, and more prominent inferiorly. This
difference in the length of the two condyles is only observed when the bone is
perpendicular and depends upon the obliquity of the thigh bones, in consequence
of their separation above at the articulation with the pelvis. If the femur is
held obliquely, the surfaces of the two condyles will be seen to be nearly hori-
228
THE SKELETON
zontal. The two condyles are directly continuous in front, and form a smooth,
trochlear surface, the trochlea, which articulates with the patella. It presents
a median groove, which extends downward and backward to the intercondyloid
notch; and two lateral convexities, of which the external is the broader, more
prominent, and prolonged farther upward upon the front of the outer condyle.
The external border of this articular surface is also more prominent, and ascends
higher than the internal one. The intercondyloid notch lodges the crucial liga-
ments; it is bounded laterally by the opposed surfaces of the two condyles, and
in front by the lower end of the shaft. Between the popliteal surface and the
floor of the intercondyloid notch is an elevation (linea intercondyloidea) , which
affords attachment to the posterior ligament of the knee-joint.
Outer or External Condyle (condylus lateralis). — The outer surface of the external
condyle presents, a little behind its centre, an eminence, the outer tuberosity or outer
epicondyle (epicondylus lateralis); it is less prominent than the inner tuberosity,
and gives attachment to the external lateral ligaments of the knee. Immediately
beneath it is a groove, the popliteal groove (sulcus popliteus), which commences. at a
depression a little behind the centre of the lower border of this surface: the front
part of this depression gives origin to the Popliteus muscle, the tendon of which is
lodged in the groove during flexion of the knee. The groove is smooth, covered
with cartilage in the recent state, and runs upward and backward to the posterior
extremity of the condyle. The inner surface of the outer condyle forms one of
the lateral boundaries of the intercondyloid notch, and gives attachment, by its
posterior part, to the anterior crucial ligament. The inferior surface is convex,
smooth, and broader than that of the internal condyle. The posterior extremity
is convex and smooth: just above and to the outer side of the articular surface
is a depression for the tendon of the outer head of the Gastrocnemius, above
which is the origin of the Plantaris.
Inner or Internal Condyle (condylus medialis). — The inner surface of the inner
condyle presents a convex eminence, the inner tuberosity or inner epicondyle (epi-
condylus medialis), rough for the attachment of the internal lateral ligament. The
outer side of the inner condyle forms one of the
lateral boundaries of the intercondyloid notch,
and gives attachment, by its anterior part, to the
posterior crucial ligament. Its inferior or articu-
lar surface is convex, and presents a less exten-
sive surface than the external condyle. Just
above the articular surface of the condyle,
behind, is a depression for the tendon of origin
of the inner head of the Gastrocnemius.
Structure. — The shaft of the femur is a
cylinder of compact tissue, hollowed by a
large medullary canal. The cylinder is of great
thickness and density in the middle third of
the shaft, where the bone is narrowest and the
medullary canal well formed; but above and
below this the cylinder gradually becomes
thinner, owing to a separation of the layers of
the bone into cancelli, which project into the
.n^l..^.-., ~nnal anrl firmllv nHlitprfltp it SO
medullary Canal anc mail/ II, »
that the upper and lower ends of the shaft, and
the articular extremities more especially, consist of cancellated tissue invested
by a thin, compact layer.
The arrangement of the cancelli in the ends of the femur is remarkable. In
the upper end they are arranged in two sets. One, starting from the top of the
FIG. 164. — Diagram showing the arrangement
of the bone-fibres of the neck of the femur.
THE FEMUR, OR THIGH BONE
229
lead, the upper surface of the neck, and the great trochanter, converge to the inner
3ircumference of the shaft (Figs. 164 and 165); these are placed in the direction of
satest pressure, and serve to support the vertical weight of the body. The second
are planes of lamellae intersecting the former nearly at right angles, and are
FIG. 165. — Right femur, upper extremity, ground frontal section, from in front. (Spalteholz.)
situated in the line of the greatest tension — that is to say, along the lines in which
the muscles and ligaments exert their traction. In the head of the bone these
planes are arranged in a curved form, in order to strengthen the bone when exposed
to pressure in all directions. In the midst of the cancellous tissue of the neck is
a vertical plane of compact bone, the femoral spur (calcar femorale), which com-
230
THE SKELETON
mences at the point where the neck joins the shaft midway between the lesser
trochanter and th^ internal border of the shaft of the bone, and extends in the
direction of the digital fossa (Fig. 167). This materially strengthens this portion
of the bone. Another point in connection with the structure of the neck of the
femur requires mention, especially on account of its influence on the production
FIG. 166. — Architecture of head of femur as shown by the x-ray.
of fracture in this situation. It will be noticed that a considerable portion of the
great trochanter lies behind the level of the posterior surface of the neck; and if a
section be made through the trochanter at this level, it will be seen that the pos-
terior wall of the neck is prolonged into the trochanter. This prolongation is
termed by Bigelow the true neck,1 and forms a thin, dense plate of bone, which
passes beneath the posterior intertrochanteric ridge toward the outer surface of
the bone. In the lower end the cancelli spring on all sides from the inner surface
of the cylinder, and descend in a perpendicular direction to the articular surface,
the cancelli being strongest and having a more accurately perpendicular course
above the condyles. In addition to this, however, horizontal planes of cancellous
tissue are to be seen, so that the spongy tissue in this situation presents an appear-
ance of being mapped out into a series of rectangular areas.
' Bigelow on the Hip, p. 121.
Articulations. — With three bones: the os innominatum, tibia, and patella.
Development (Fig. 168). — The femur is developed by five centres: one for the
shaft, one for each extremity, and one for each trochanter. Of all the long bones,
ccept the clavicle, it is the first to show traces of ossification : this commences in
le shaft, at about the seventh week of foetal life, the centres of ossification in the
-piphyses appearing in the following order: First, in the lower end of the bone,
it the' ninth month of foetal life1 (from this the condyles and tuberosities are
Great trochanter.
_ Digital fossa.
THE FEMUR, OR THIGH BONE
231
Appears at 4th
year ; joins shaft ^
about 18th year.
Lesser
trochanter.
Appears at
9th month
(festal).
Appears at end
of 1st year;
joins shaft about
18th year.
Appears 13th-14th year ;
& joins shaft about 18th
year.
Joins shaft at 20th
year.
FIG. 167. — Calcar femorale.
Lower extremity.
FIG. 168. — Plan of the development of the femur,
five centres.
By
formed); in the head at the end of the first year after birth; in the great tro-
chanter, during the fourth year; and in the lesser trochanter, between the thir-
teenth and fourteenth. The order in which the epiphyses are joined to the shaft
is the reverse of that of their appearance: their junction does not commence until
after puberty, the lesser trochanter being first joined, then the great, then the
head, and, lastly, the inferior extremity (the first in which ossification commenced),
which is not united until the twentieth year.
Attachment of Muscles. — To twenty-three. To the great trochanter: the Glu-
teus medius, Gluteus minimus, Pyriformis, Obturator internus, Obturator externus,
Gemellus superior, Gemellus inferior, and Quadratus femoris. To the lesser
trochanter: the Psoasmagnus and the Iliacus below it. To the shaft: the Vastus
externus, Gluteus maximus, short head of the Biceps, Vastus internus, Adductor
magnus, Pectineus, Adductor brevis, Adductor longus, Crureus, and Subcrureus.
To the condyles: the Gastrocnemius, Plantaris, and Popliteus.
Surface Form. — The femur is covered with muscles, so that in fairly muscular subjects the
shaft is not to be detected through its fleshy covering, and the only parts accessible to the touch
are the outer surface of the great trochanter and the lower expanded end of the bone. The
external surface of the great trochanter is to be felt, especially in certain positions of the limb. Its
1 This is said to be the only epiphysis in which ossification begins before birth; though according to some
observers, the centre for the upper epiphysis of the tibia also appears before birth. — ED. of 15th English
Edition.
232 THE SKELETON
position is generally indicated by a depression, owing to the thickness of the Gluteus medius and
minimus, which project above it. When, however, the thigh is flexed, and especially if crossed
over the opposite one, the trochanter produces a blunt eminence on the surface. The upper
border is about on a line with the spine of the os pubis, and its exact level is indicated by a
line drawn from the anterior superior spinous process of the ilium, over the outer side of the
hip, to the most prominent point of the tuberosity of the ischium. This is known as Nelaton's
line. The outer and inner condyles of the lower extremity are easily to be felt. The outer one
is more subcutaneous than the inner one and readily felt. The tuberosity on it is comparatively
little developed, but can be more or less easily recognized. The inner condyle is more thickly
covered, and this gives a general convex outline to this part, especially when the knee is flexed.
The tuberosity on it is easily felt, and at the upper part of the condyle the sharp tubercle for the
insertion of the tendon of the Adductor magnus can be recognized without difficulty. When
the knee is flexed, and the patella situated in the interval between the condyles and the upper
end of the tibia, a part of the trochlear surface of the femur can be made out above the patella.
Surgical Anatomy. — There are one or two points about the ossification of the femur bear-
ing on practice to which allusion must be made. It has been stated above that the lower end
of the femur is the only epiphysis in which ossification has commenced at the time of birth.
The presence of the ossific centre in newly born children found dead is, therefore, a proof
that the child has arrived at the full period of utero-gestation, and is always relied upon in
medico-legal investigations. The position of the epiphysial line should be carefully noted. It
is on a level with the adductor tubercle, and the epiphysis does not, therefore, form the whole
of the cartilage-clad portion of the lower end of the bone. It is essential to bear this point in
mind in performing excision of the knee, since growth in length of the femur takes place chiefly
from the lower epiphysis, and any interference with the epiphysial cartilage in a young child
would involve such ultimate shortening of the limb, from want of growth, as to render it almost
useless. Separation of the lower epiphysis may take place up to the age of twenty, at which
time it becomes completely joined to the shaft of the bone; but, as a matter of fact, few cases
occur after the age of sixteen or seventeen. The epiphysis of the head of the femur is of interest
principally on account of its being the seat of origin of a large number of cases of tuberculous
disease of the hip-joint. The disease commences in the majority of cases in the highly vascular
and growing tissue in the neighborhood of the epiphysis, and from here extends into the joint.
In the condition known as coxa vara the head of the femur falls to a lower level than normal.
The angle between the neck and shaft is greatly diminished and may become a right angle or
the head may actually descend to a lower level than that of the trochanter. The neck is also
bent with a convexity forward ; coxa vara is due to rickets.
Fractures of the femur are divided, like those of the other long bones, into fractures of the
upper end; of the shaft; and of the lower end. The fractures of the upper end may be classi-
fied into (1) fracture of the neck; (2) fracture at the junction of the neck with the great trochanter;
(3) fracture of the great trochanter; and (4) separation of the epiphysis, either of the head or
of the great trochanter. The first of these, fracture of the neck, is usually termed intracapsular
fracture, but this is scarcely a correct designation, as owing to the attachment of the capsular
ligament, the fracture may be partly within and partly without the capsule, when the fracture
occurs at the lower part of the neck. It generally occurs in old people, principally women, and
usually from a very slight degree of indirect violence. Probably the main cause of the fracture
taking place in old. people is in consequence of the degenerative changes which the bone has
undergone. Merkel believes that it is mainly due to the absorption of the calcar femorale.
These fractures are occasionally impacted. As a rule they unite by fibrous tissue, and frequently
iio union takes place, and the surfaces of the fracture become smooth and eburnated. The
lack of reparative power in intracapsular fracture is due to lack of apposition of the fragments and
diminution in the amount of blood sent to the smaller fragment. The head of the bone receives
blood from the neck through the reflected portions of the capsule and through the Ligamentum
teres. A fracture cuts off the supply by the neck and by the reflected portions of the capsule.
Fractures at the junction of the neck with the great trochanter are usually termed extra-
capsular, but this designation is also incorrect; as the fracture is partly within the capsule,
owing to its attachment in front to the anterior intertrochanteric line, which is situated below
the line of fracture. These fractures are produced by direct violence to the great trochanter, as
from a blow or fall laterally on the hip. From the manner in which the accident is caused, the
neck of the bone is driven into the trochanter, where it may remain impacted or the trochanter
may be split up into two or more fragments, and thus no fixation takes place.
Fractures of the great trochanter may be either 'oblique fracture through the trochanter
major, without implicating the neck of the bone" (Astley Cooper), or separation of the great
trochanter. Most of the recorded cases of this latter injury occurred in young persons, and
were probably cases of separation of the epiphysis of the great trochanter. Separation of the
epiphysis of the head of the femur has been said to occur, but has probably never been verified
by post-mortem examination.
Fractures of the shaft may occur at any part, but the most usual situation is at or near the
THE PATELLA, OR KNEE-CAP
233
entre of the bone. They may be caused by direct or indirect violence or by muscular action.
Fractures of the upper third of the shaft are almost always the result of indirect violence, whilst
lose of the lower third are the result, for the most part, of direct violence. In the middle third
•actures occur from both forms of injury in about equal proportions. Fractures of the shaft
generally oblique, but they may be transverse, longitudinal, or spiral. The transverse
eture occurs most frequently in children. The fractures of the lower end of the femur include
insverse fracture above the condyles, the most common; and this may be complicated by a
jrtical fracture between the condyles, constituting the T-shaped fracture. In these cases the
pliteal artery is in danger of being wounded. Oblique fracture, separating either the internal
external condyle, and a longitudinal incomplete fracture between the condyles, may also take
alace.
The femur and also the bones of the leg are frequently the seat of acute osteomyelitis in young
lildren. This is no doubt due to their greater exposure to injury, which is often the exciting
luse of this disease. Tumors not unfrequently are found growing from the femur: the most
3mmon forms being sarcoma, which may grow either from the periosteum or from the medullary
tissue within the interior of the bone; and exostosis, which is commonly found originating in
le neighborhood of the epiphysial cartilage of the lower end.
Genii varum is a form of bow-leg in which the tibia and femur are curved outward, the knees
ging widely separated. Both extremities are usually affected. In early life the disease is due
rickets. In elderly people it may be due to arthritis deformans. Genu valgum (knock-knee]
a condition in which the knees are close together, the feet are wide apart, and the internal
iteral ligament of the knee-joint is stretched. It is due to excessive growth of the inner con-
lyle of the femur, the shaft of the femur curving inward. It may be due to rickets, attitude of
in occupation, or flat-foot, and one or both knees may be affected.
THE LEG.
The skeleton of the leg consists of three bones; the patella, a large sesamoid
>ne, placed in front of the knee; the tibia; and the fibula.
The Patella, or Knee-cap (Fig. 169).
The patella (patella, a small pan), the knee-cap or knee-pan, is a flat, triangular
>ne, situated at the anterior part of the knee-joint. It is usually regarded as a
jsamoid bone, developed in the tendon of the Quadriceps extensor. It resembles
icse bones (1) in its being developed in a tendon; (2) in its centre of ossification
^resenting a knotty or tuberculated outline; (3) in its structure being composed
minly of dense cancellous tissue, as in the other sesamoid bones. It serves to
protect the front of the joint, and increases the leverage of the Quadriceps extensor
by making it act at a greater angle. It presents an anterior and a posterior sur-
face, three borders, and an apex.
Surfaces. Anterior Surface. — The anterior surface is convex, perforated by
small apertures, for the passage of nutrient vessels, and marked by numerous
rough, longitudinal striae. This surface is covered, in the recent state, by an
expansion from the tendon of
the Quadriceps extensor, which
is continuous below with the
superficial fibres of the liga-
inentum patellae. It is sepa-
rated from the integument by
a bursa.
Posterior Surface. — The pos-
terior surface presents a
smooth, oval-shaped, articular
surface (fades articularis) , cov- FlG 169._Right patella. a> anterior surface. 6, poster-or 8urface.
ered with cartilage in the re-
cent state, and divided into two facets by a vertical ridge, which descends from
the superior border toward the inferior angle of the bone. The ridge corresponds
to the groove on the trochlear surface of the femur, and the two facets to the
articular surfaces of the two condyles; the outer facet, for articulation with the
234 THE SKELETON
outer condyle, being broader and deeper. This character serves to indicate
the side to which the bone belongs. Below the articular surface is a rough, convex,
non-articular depression, the lower half of which gives attachment to the liga-
mentum patellte, the upper half being separated from the head of the tibia by
adipose tissue.
Borders. Superior Border. — The superior border (basis patella) is thick, and
sloped from behind, downward and forward: it gives attachment to that portion
of the Quadriceps extensor which is derived from the Rectus and Crureus muscles.
Lateral Borders. — The lateral borders are thinner, converging below. They
give attachment to that portion of the Quadriceps extensor derived from the
external and internal Vasti muscles.
The Apex (apex patellae). — The apex is pointed, and gives attachment to the
ligamentum patellae.
Structure. — It consists of a nearly uniform, dense cancellous tissue covered
by a thin compact lamina. The cancelli immediately beneath the anterior surface
are arranged parallel with it. In the rest of the bone they radiate from the pos-
terior articular surface toward the other parts of the bone.
Development. — By a single centre, which makes its appearance, according to
Be*clard, about the third year. In two instances Mr. Pick has seen this bone car-
tilaginous throughout, at a much later period (six years). More rarely, the bone is
developed by two centres, placed side by side. Ossification is completed about
the age of puberty.
Articulations. — With the two condyles of the femur.
Attachment of Muscles. — To four: the Rectus, Crureus, Vastus internus, and
Vastus externus. These muscles, joined at their insertion, constitute the Quadri-
ceps extensor cruris.
Surface Form. — The external surface of the patella can be seen and felt in front of the
knee. In the extended position of the limb the internal border is a little more prominent than
the outer, and if the Quadriceps extensor is relaxed the bone can be moved from side to side and
appears to be loosely fixed. If the joint is flexed, the patella recedes into the hollow between the
condyles of the femur and the upper end of the tibia, and becomes firmly fixed against the femur.
Surgical Anatomy. — The main surgical interest about the patella is in connection with
fractures, which are of common occurrence. They may be produced by muscular action; that
is to say, by violent contraction of the Quadriceps extensor while the limb is in a position of
semi-flexion, so that the bone is snapped across the condyles; or by direct violence, such as
falls on the knee. Most fractures are due to muscular action ; in fact, the patella is more often
broken by muscular action than is any other bone. In fractures by muscular action the line of
fracture is transverse. In fractures by direct force the line of fractuure may be oblique, longi-
tudinal, stellate, or the bone variously comminuted. The principal interest in these cases
attaches to their treatment. Owing to the wide separation of the fragments, and the diffi-
culty there is in maintaining them in apposition, union takes place by fibrous tissue, and this
may subsequently stretch, producing wide separation of the fragments and permanent lame-
ness. Various plans, including opening the joint and suturing the fragments, have been advo-
cated for overcoming this difficulty. In many cases a portion of fascia or capsule gets between
the fragments. In such a condition operation is necessary.
In the larger number of cases of fracture of the patella the knee-joint is involved, the car-
tilage which covers its posterior surface being torn, the synovial membrane lacerated, the lateral
fibrous expansions ruptured, and the patellar bursa torn open. In cases of fracture from
direct violence, however, this need not necessarily happen, the lesion may involve only the
superficial part of the bone; and, as Morris has pointed out, it is an anatomical possibility, in
complete fracture, if the lesion involve only the lower and non-articular part of the bone, for
it to take place without injury to the synovial membrane.
The Tibia, or Shin Bone (Figs. 170, 171).
The tibia (tibia, a flute or pipe) is situated at the front and inner side of the
leg, and, excepting the femur, is the longest and largest bone in the skeleton. It
is prismoid in form, expanded above, where it enters into the knee-joint, more
THE TIBIA, OR SHIN BONE
235
Head
Styloid process.
Tibia.
Internal malleolus.
External malleolus.
FIG. 170. — Bones of the right leg. Anterior surface. FIG. 171. — Bones of the right leg. Posterior surface.
Styloid process.
Fibula.
236 THE SKELETON
slightly enlarged below. In the male its direction is vertical and parallel with
the bone of the opposite side ; but in the female it has a slightly oblique direction
downward and outward, to compensate for the oblique direction of the femur
inward. It presents for examination a shaft and two extremities.
Upper Extremity. — The upper extremity, or head, is large, and expanded
on each side into two lateral eminences, the internal and external tuberosities
(condylus medialis and condylus lateralis}. Superiorly, each tuberosity presents
a smooth, concave surface (fades articularis superior), which articulates with
ATTACHMENT OF POSTERIOR «_._.... -,_ poQTrBlOB ATTACHMENT OF POSTERIOR
EXTREMITY OF EXTERNAL Q p ,!T °R J " ' ° " EXTREMITY OF INTERNAL
SEMI LUNAR CARTILAGE, CRUC, A L LIGAMENT ?EMILUNAR CART.LAGE
ATTACHMENT OF ANTERIOR' -_.-... __ '__ ^ATTACHMENT OF ANTERIOR
EXTREMITY OF EXTERNAL _?"''„ rvT = Ii "TH EM ITY OF I NTERN AL
SEMILUNAH CARTILAGE J!?" *? .^T^^2 SEMILUNAR CARTILAGE
FIG. 172. — Upper articular surface of the tibia, showing the attachments of the ligaments.
(Poirier and Charpy.)
a condyle of the femur. The internal, articular surface is longer, deeper, and
narrower than the external, oval from before backward, to articulate with the in-
ternal condyle; the external one is broader and more circular, concave from side
to side, but slightly convex from before backward, especially at its posterior part,
where it is prolonged on to the posterior surface for a short distance, to articulate
with the external condyle. Between the two articular surfaces, and nearer the pos-
terior than the anterior aspect of the bone, is an eminence, the spinous process
of the tibia (eminentia intercondyloidea) ; surmounted by a prominent tubercle on
each side (the tuberculum intercondyloideum mediate and the tuberculum inter-
condyloideum laterale) , on to the lateral aspect of which the facets just described
are prolonged; in front and behind the spinous process is a rough depression
(fossa intercondyloidea anterior and the fossa intercondyloidea posterior) for the
attachment of the anterior and posterior crucial ligaments arid the semilunar
fibro-cartilages (Fig. 172).
The anterior surfaces of the tuberosities are continuous with one another, form-
ing a single large surface, which is somewhat flattened: it is triangular, broad
above, and perforated by large vascular foramina; narrow below, where it ter-
minates in a prominent oblong elevation of large size, the tubercle of the tibia
(tuberositas tibae); the lower half of this tubercle is rough, for the attachment of
the ligamentum patellae; the upper half presents a smooth facet supporting, in the
recent state, a bursa which separates the ligament from the bone. Posteriorly the
tuberosities are separated from each other by a shallow depression, the popliteal
notch (indsura poplitea) , which gives attachment to part of the posterior crucial
ligament and part of the posterior ligament of the knee-joint. The inner tuberosity
presents posteriorly a deep transverse groove, for the insertion of one of the fas-
ciculi of the tendon of the Semi-membranosus. Its lateral surface is convex,
rough, and prominent, and gives attachment to the internal lateral ligament. The
outer tuberosity presents posteriorly a flat articular facet (fades articularis fibularis),
nearly circular in form, directed downward, backward, and outward, for articu-
lation with the fibula. Its lateral surface is convex and rough, more prominent
in front than the internal, and presents a prominent rough eminence, situated on
THE TIBIA, OR SHIN BONE 237
a level with the upper border of the tubercle of the tibia at the junction of its
anterior and outer surfaces, for the attachment of the ilio-tibial band. Just below
this the Extensor longus digitorum and a slip from the Biceps are attached. The
infraglenoid margin (margo infraglenoidalis) is at the outer edge of the superior
articular surface. From this point the bone rapidly narrows distally.
Shaft of the Tibia (corpus tibice). — The shaft of the tibia is of a triangular
prismoid form, broad above, gradually decreasing in size to its most slender part,
at the commencement of its lower fourth, where fracture most frequently occurs;
it then enlarges again toward its lower extremity. It presents for examination
three borders and three surfaces.
Anterior Border. — The anterior border, the most prominent of the three, is
called the crest of the tibia (crista anterior) , or, in popular language, the shin ; it
commences above at the tubercle, and terminates below at the anterior margin
of the inner malleolus. This border is very prominent in the upper two-thirds of
its extent, smooth and rounded below. It presents a very flexuous course, being
usually curved outward above and inward below; it gives attachment to the
deep fascia of the leg.
Internal Border (margo medialis). — The internal border is smooth and rounded
above and below, but more prominent in the centre; it commences at the back
part of the inner tuberosity, and terminates at the posterior border of the inter-
nal malleolus ; its upper part gives attachment to the internal lateral ligament of
the knee to the extent of about two inches, and to some fibres of the Popliteus
muscle, and its middle third to some fibres of the Soleus and Flexor longus
digitorum muscles.
External Border (crista inter ossea}. — The external border, or interosseous ridge,
is thin and prominent, especially its central part, and gives attachment to the
interosseous membrane ; it commences above in front of the fibular articular facet,
and bifurcates below, to form the boundaries of a triangular rough surface, for
the attachment of the interosseous ligament connecting the tibia and fibula.
Internal Surface (fades medialis). — The internal surface is smooth, convex,
and broader above than below; its upper third, directed forward and inward, is
covered by the aponeurosis derived from the tendon of the Sartorius, and by the
tendons of the Gracilis and Semitendinosus, all of which are inserted nearly as
far forward as the anterior border; in the rest of its extent it is subcutaneous.
External Surface (fades lateralis). — The external surface is narrower than the
internal; its upper two-thirds presents a shallow groove for the attachment of
the Tibialis anticus muscle; its lower third is smooth, convex, curves gradually
forward to the anterior aspect of the bone, and is covered from within outward by
the tendons of the following muscles: Tibialis anticus, Extensor proprius hallucis,
Extensor longus digitorum.
Posterior Surface (jades posterior). — The posterior surface (Fig. 171) presents,
at its upper part, a prominent ridge, the popliteal line or the oblique line of the
tibia (linea poplitea), which extends from the back part of the articular facet
for the fibula obliquely downward, to the internal border, at the junction of
its upper and middle thirds. It marks the lower limit for the insertion of the
Popliteus muscle, and serves for the attachment of the popliteal fascia and part
of the Soleus, Flexor longus digitorum, and Tibialis posticus muscles; the tri-
angular concave surface, above and to the inner side of this line, gives attach-
ment to the Popliteus muscle. The middle third of the posterior surface is
divided by a vertical ridge into two lateral halves: the ridge is well marked at
its commencement at the oblique line, but becomes gradually indistinct below;
the inner and broader half gives attachment to the Flexor longus digitorum, the
outer and narrower to part of the Tibialis posticus. The remaining part of the
bone presents a smooth surface covered by the Tibialis posticus, Flexor longus
238 THE SKELETON
digitorum, and Flexor longus hallucis muscles. Immediately below the oblique
line is the nutritive foramen (foramen nutridum), which is large and directed
obliquely downward. It is the opening of the nutrient canal, which is directed
toward the periphery.
Lower Extremity. — The lower extremity, much smaller than the upper,
presents five surfaces; it is prolonged downward, on its inner side, to a strong
process, the internal malleolus (malleolus medialis).
Inferior Surface (fades articularis inferior). — The inferior surface of the bone
is quadrilateral, and smooth for articulation with the astragalus. This surface
is concave from before backward, and broader in front than behind. It is trav-
ersed from before backward by a slight elevation, separating two lateral depres-
sions. It is narrow internally, where the articular surface becomes continuous
with that on the inner malleolus (fades articularis malleolaris) .
Anterior Surface. — The anterior surface of the lower extremity is smooth and
rounded above, and covered by the tendons of the Extensor muscles of the toes;
its lower margin presents a rough transverse depression, for the attachment of
the anterior ligament of the ankle-joint.
Posterior Surface. — The posterior surface presents a superficial groove directed
obliquely downward and inward, continuous with a similar groove on the posterior
surface of the astragalus, and serving for the passage of the tendon of the Flexor
longus hallucis.
External Surface. — The external surface presents a triangular rough depression
for the attachment of the interior interosseous ligament, connecting it with the
fibula; the lower part of this depression, the fibular notch (incisura fibularis), is
smooth, covered with cartilage in the recent state, and articulates with the fibula.
This surface is bounded by two prominent borders, continuous above with the
interosseous ridge; they afford attachment to the anterior inferior and posterior
inferior tibio-fibular ligaments.
Internal Surface. — The internal surface of the lower extremity is prolonged
downward to form a strong pyramidal process, flattened from without inward —
the internal malleolus (malleolus medialis). The inner surface of this process is
convex and subcutaneous; its outer surface is smooth and slightly concave, and
articulates with the astragalus; its anterior border is rough, for the attachment of
the anterior fibres of the internal lateral or Deltoid ligament; its posterior border
presents a broad and deep groove (sulcus malleolaris), directed obliquely down-
ward and inward, which is occasionally double: this groove transmits the tendons
of the Tibialis posticus and Flexor longus digitorum muscles. The summit of the
internal malleolus is marked by a rough depression behind, for the attachment of
the internal lateral ligament of the ankle-joint.
Structure. — Like that of the other long bones. At the junction of the middle
and. lower third, where the bone is smallest, the wall of the shaft is thicker than
in other parts, in order to compensate for the smallness of the calibre of the bone.
Development. — By three centres (Fig. 173) : one for the shaft and one for
each extremity. Ossification commences in the centre of the shaft about the
seventh week, and gradually extends toward either extremity. The centre for the
upper epiphysis appears before or shortly after birth; it is flattened in form, and
has a thin, tongue-shaped process in front which forms the tubercle. That for
the lower epiphysis appears in the second year. The lower epiphysis joins the
shaft at about the eighteenth, and the upper one about the twentieth year. Two
additional centres occasionally exist — one for the tongue-shaped process of the
upper epiphysis, which forms the tubercle, and one for the inner malleolus.
Articulations. — With three bones: the femur, fibula, and astragalus
Attachment of Muscles. — To twelve: to the inner tuberosity, the Semimem-
branosus; to the outer tuberosity, the Tibialis anticus and Extensor longus digi-
THE FIBULA, OR CALF BONE
239
Upper extremity.
Appears at
birth.
roins shaft about
20th year.
torum and Biceps; to the shaft, its internal surface, the Sartorius, (Jracilis, and
Semitendinosus; to its external surface, the Tibialis anticus; to its posterior sur-
face, the Popliteus, Soleus, Flexor longus digi torum, and Tibialis posticus; to the
tubercle, the ligamentum patellae, by which the Quadriceps extensor muscle is
inserted into the tibia. In addition to
these muscles, the Tensor fasciae femoris
is inserted indirectly into the tibia, through
the ilio-tibial band, and the Peroneus lon-
gus occasionally derives a few fibres of
origin from the outer tuberosity.
Surface Form. — A considerable portion of the
tibia is subcutaneous and easily to be felt. At
the upper extremity the tuberosities are to be
recognized just below the knee. The internal
one is broad and smooth, and merges into the
subcutaneous surface of the shaft below. The
external one is narrower and more prominent,
and on it, about midway between the apex of the
patella and the head of the fibula, may be felt a
prominent tubercle for the insertion of the iiio-
tibial band. In front of the upper end of the
bone, between the tuberosities, is the tubercle of
the tibia, forming an oval eminence which is con-
tinuous below with the anterior border or crest
of the bone. This border can be felt, forming
the prominence of the shin, in the upper two-
thirds of its extent as a sharp and flexuous ridge,
curved outward above and inward below. In
the lower third of the leg the border disappears,
and the bone is concealed by the tendons of the
muscles on the front of the leg. Internal to the
anterior border is to be felt the broad internal
surface of the tibia, slightly encroached upon by the muscles in front and behind. It com-
mences above at the wide expanded inner tuberosity, and terminates below at the internal
malleolus. The internal malleolus is a broad prominence situated on a higher level and some-
what farther forward than the external malleolus. It overhangs the inner border of the arch
of the foot. Its anterior border is nearly straight; its posterior border presents a sharp edge
which forms the inner margin of the groove for the tendon of the Tibialis posticus muscle.
Appears at 2nd_
year.
Joins shaft about
18th year.
Lower extremity.
FIG. 173. — Plan of the development of the tibia.
By three centres.
The Fibula, or Calf Bone (Figs. 170, 171).
The fibula (fibula, a clasp) is situated at the outer side of the leg. It is the
smaller of the two bones, and, in proportion to its length, the most slender of all
the long bones; it is placed on the outer side of the tibia, with which it is con-
nected above and below. Its upper extremity is small, placed toward the back of
the head of the tibia and below the level of the knee-joint, and excluded from its
formation; the lower extremity inclines a little forward, so as to be on a plane
anterior to that of the upper end, projects below the tibia, and forms the outer
ankle. It presents for examination a shaft and two extremities.
Upper Extremity. — The upper extremity, or head (capitulum fibulae], is of
an irregular quadrate form, presenting above a flattened articular facet, directed
upward, forward, and inward, for articulation with a corresponding facet on the
external tuberosity of the tibia. On the outer side is a thick and rough promi-
nence, continued behind into a pointed eminence, the styloid process of the fibula
(apex capituli fibula?), which projects upward from the posterior part of the
head. The prominence gives attachment to the tendon of the Biceps muscle
and to the long external lateral ligament of the knee, the ligament dividing the
tendon into two parts. The summit of the styloid process gives attachment to
240 THE SKELETON
the short external lateral ligament. The remaining part of the circumference of the
head is rough, for the attachment of muscles and ligaments. It presents in front
a tubercle for the origin of the upper and anterior part of the Peroneus longus, and
the adjacent surface gives attachment to the anterior superior tibio-fibular liga-
ment; and behind, another tubercle for the attachment of the posterior superior
tibio-fibular ligament and the upper fibres of the Soleus muscle.
Shaft of the Fibula (corpus fibulw). — The shaft presents four borders —
the antero-external, the antero-internal, the postero-external, and the postero-
internal; and four surfaces — anterior, posterior, internal, and external.
Antero-external Border (crista anterior) . — The antero-external border commences
above in front of the head, runs vertically downward to a little below the middle of
the bone, arid then, curving somewhat outward, bifurcates so as to embrace the
triangular subcutaneous surface immediately above the outer surface of the exter-
nal malleolus. This border gives attachment to an intermuscular septum, which
separates the extensor muscles on the anterior surface of the leg from the Peroneus
longus and brevis muscles on the outer surface.
Antero-internal Border (crista interossea) .—The antero-internal border, or inter-
osseous ridge, is situated close to the inner side of the preceding, and runs nearly
parallel with it in the upper third of its extent, but diverges from it so as to
include a broader space in the lower two-thirds. It commences above, just
beneath the head of the bone (sometimes it is quite indistinct for about an
inch below the head), and terminates below at the apex of a rough triangular
surface immediately above the articular facet of the external malleolus. It serves
for the attachment of the interosseous membrane, which separates the extensor
muscles in front from the flexor muscles behind.
Postero-external Border (crista lateralis) . — The postero-external border is promi-
nent ; it commences above at the base of the styloid process, and terminates below
in the posterior border of the outer malleolus. It is directed outward above, back-
ward in the middle of its course, backward and a little inward below, and gives
attachment to an aponeurosis which separates the Peronei muscles on the outer
surface of the shaft from the flexor muscles on its posterior surface.
Postero-internal Border (crista medialis). — The postero-internal border, some-
times called the oblique line, commences above at the inner side of the head,
and terminates by becoming continuous with the antero-internal border or inter-
osseous ridge at the lower fourth of the bone. It is well marked and promi-
nent at the upper and middle parts of the bone. It gives attachment to an
aponeurosis which separates the Tibialis posticus from the Soleus above and the
Flexor longus hallucis below.
Anterior Surface (fades anterior) , — The anterior surface is the interval between
the antero-external and antero-internal borders. It is extremely narrow and flat
in the upper third of its extent; broader and grooved longitudinally in its lower
third; it serves for the attachment of three muscles, the Extensor longus digitorum,
Peroneus tertius, and Extensor proprius hallucis.
External Surface (fades lateralis). — The external surface is the space between
the antero-external and postero-external borders. It is much broader than the
preceding, and often deeply grooved, is directed outward in the upper two-thirds
of its course, backward in the lower third, where it is continuous with the poste-
rior border of the external malleolus. This surface is completely occupied by
the Peroneus longus and brevis muscles.
Internal Surface (facies medialis). — The internal surface is the interval included
between the antero-internal and the postero-internal borders. It is directed
inward, and is grooved for the attachment of the Tibialis posticus muscle.
Posterior Surface (facies posterior). — The posterior surface is the space included
between the postero-external and the postero-internal borders, it is continuous
THE FIBULA, OR CALF BONE
241
below with the rough triangular surface above the articular facet of the outer
malleolus; it is directed backward above, backward and inward at its middle,
directly inward below. Its upper third is rough, for the attachment of the Soleus
muscle; its lower part presents a triangular rough surface, connected to the tibia
by a strong interosseous ligament, and between these two points the entire surface
is covered by the fibres of origin of the Flexor longus hallucis muscle. At about
the middle of this surface is the nutrient foramen (foramen nutricium). It opens
into the nutrient canal (canalis nutricius) , which is directed downward.
Lower Extremity. — The lower extremity, or external malleolus (malleolus
lateralis], is of a pyramidal form, somewhat flattened from without inward, and
is longer, and descends lower than the internal malleolus. Its external surface is
convex, subcutaneous, and continuous with the triangular (also subcutaneous)
surface on the outer side of the shaft. The internal surface presents in front a
smooth triangular facet (fades articularis malleoli). broader above than below, and
convex from above downward, which articulates with a corresponding surface on
the outer side of the astragalus. Behind and beneath the articular surface is a
rough depression which gives attachment to the posterior fasciculus of the external
lateral ligament of the ankle. The anterior border is thick and rough, and marked
below by a depression for the attachment of the anterior fasciculus of the external
lateral ligament. The posterior border is broad and marked by a shallow groove
(sulcus malleolaris) , for the passage of the tendons of the Peroneus longus and
brevis muscles. The summit is rounded, and gives attachment to the middle
fasciculus of the external lateral ligament.
In order to distinguish the side to which the bone belongs, hold it with the
lower extremity downward and the broad groove for the Peronei tendons back-
ward— i.e., toward the holder; the triangular subcutaneous surface will then be
directed to the side to which the bone belongs.
Articulations.— With two bones: the tibia and
astragalus.
Development. — By three centres (Fig. 174): one
for the shaft, and one for each extremity. Ossification
commences in the shaft about the eighth week of foetal
life, a little later than in the tibia, and extends gradu-
ally toward the extremities. At birth both ends are
cartilaginous. Ossification commences in the lower
end in the second year, and in the upper one about the
fourth year. The lower epiphysis, the first in which
ossification commences, becomes united to the shaft
about the twentieth year; the upper epiphysis joins
about the twenty-fifth year. Ossification appearing
first in the lower epiphysis is contrary to the rule
which prevails with regard to the commencement of
ossification in epiphyses — viz., that epiphysis toward
which the nutrient artery is directed commences to
ossify last; but it follows the rule which prevails with
regard to the union of epiphyses, by uniting first.
Attachment of Muscles. — To nine: to the head,
the Biceps, Soleus, and Peroneus longus; to the shaft,
its anterior surface, the Extensor longus digitorum,
Peroneus tertius, and Extensor proprius hallucis; to Flo 174._PiaTof'heTevdopment
the internal surface, the Tibiahs posticus; to the pos- of the fibula. By three centres.
terior surface, the Soleus and Flexor longus hallucis, to the external surface, the
Peroneus longus and brevis.
Surface Form. — The only parts of the fibula which are to be felt are the head and the lower
part of the external surface of the shaft and the external malleolus. The head is to be seen
16
Upper extremity.
Appears about ,
4th year.
I'n it en about
25th year.
Appears at
2nd year. ~
Unites about
20th year.
242
THE SKELETON
Groove for PERONEUS LONQUS
Groove for PERONEUS BREVIS.
PERONEUS TERTIUS
PERONEUS BREVIS,
Groove for tendon of
FLEXOR LONQUS HALLUCIS.
Tarsus.
Metatarsus.
Innermost tendon of
EXTENSOR BREVIS DIQITORUM.
'Tiaftl Phalanges.
EXTENSOR LONQUS HALUICIS.
FIG. 175 — Bones of the right foot. Dorsal surface.
THE FOOT
243
OUTER HEAD OF ACCESSORIUS,
FLEXOR LONQUS OIQITORUM.
FIG. 176. — Bones of the right foot. Plantar surface.
244 THE SKELETON
and felt behind and to the outer side of the outer tuberosity of the tibia. It presents a small,
prominent triangular eminence slightly above the level of the tubercle of the tibia. The exter-
nal malleolus presents a narrow elongated prominence, situated on a plane posterior to the
internal malleolus and reaching to a lower level. From it may be traced the lower third or
half of the external surface of the shaft of the bone in the interval between the Peroneus tertius
in front and the other two Peronei tendons behind.
Surgical Anatomy. — In fractures of the bones of the leg both bones are usually fractured, but
either bone may be broken separately, the fibula more frequently than the tibia. Fracture of
both bones may be caused either by direct or indirect violence. When it occurs from indirect
force, the fracture in the tibia is usually at the junction of the middle and lower third of the bone.
Many causes conduce to render this the weakest part of the bone. The fracture of the fibula
is usually at rather a higher level These fractures present great variety, both as regards
their direction and condition. They may be oblique, transverse, longitudinal, or spiral. When
oblique, they are usually the result of indirect violence, and the direction of the fracture is from
behind, downward, forward, and inward in many cases, but may be downward and outward
or downward and backward. When transverse, the fracture is often at the upper part of the
bone, and is the result of direct violence. The spiral fracture usually commences as a vertical
fissure, involving the ankle-joint, and is associated with fracture of the fibula higher up. It is
the result of torsion, from twisting of the body whilst the foot is fixed.
Fractures of the tibia alone are almost always the result of direct violence, except where the
malleolus is broken off by twists of the foot. Fractures of the fibula alone may arise from indi-
rect or direct force, those of the lower end being usually the result of the former, and those
higher up being caused by a direct blow on the part.
The tibia and fibula, like the femur, are frequently the seat of acute osteomyelitis. Tuberculous
abscess is more frequently met with in the cancellous tissue of the head and lower end of the
tibia than in any other bone of the body. The abscess is of small size; very chronic, and prob-
ably the result of tuberculous osteitis in the highly vascular growing tissue at the end of the shaft
near the epiphysial cartilage in the young subject. Such an abscess in bone is called Brodie's
abscess.
The tibia is the bone which is most frequently and most extensively distorted in rickets. It
gives way at the junction of the middle and lower third, its weakest part, and presents a curve
forward and outward. Bow-leg is due to outward curvature of the femur, tibia, and fibula,
the bend being about the junction of the shafts and lower extremities.
THE FOOT (Figs. 175, 176).
The skeleton of the foot consists of three divisions: the tarsus, metatarsus, and
phalanges.
The Tarsus (Ossa Tarsi).
The bones of the tarsus are seven in number — viz., the calcaneus or os calcis,
astragalus, cuboid, scaphoid, internal, middle, and external cuneiform.
The Calcaneus, or Heel Bone (Fig. 177). — It is also called the os calcis. The
name is derived from calx, the heel. The heel bone is the largest and strongest of
the tarsal bones. It is irregularly cuboidal in form, having its long axis directed for-
ward and outward. It is situated at the lower and back part of the foot, serving to
transmit the weight of the body to the ground, and forming a strong lever for the
muscles of the calf. It is composed of a body (corpus calcanei) , an anterior extremity
or greater process, and a posterior extremity or tuberosity (tuber calcanei). It pre-
sents for examination six surfaces: superior, inferior, external, internal, anterior,
and posterior.
Superior Surface. — The superior surface is formed behind by the upper aspect
of that part of the os calcis which projects backward to form the heel. It varies
in length in different individuals; is convex from side to side, concave from before
backward, and corresponds above to a mass of adipose substance placed in
front of the tendo Achillis. In the middle of the superior surface are two (some-
times three) articular facets, separated by a broad shallow groove (sulcus cal-
canei), which is directed obliquely forward and outward, and is rough for the
attachment of the interosseous ligament connecting the astragalus and os calcis.
When the calcaneus is in contact with the astragalus this groove is converted into
THE TARSUS 245
a canal (sinus tarsi). Of the articular surfaces, the external or posterior articular
surface (fades articidaris calcanea posterior) is the larger, and is situated on the body
of the bone: it is of an oblong form, wider behind than in front, and convex from
before backward. The internal or anterior articular surface is usually divided into
two facets. The anterior facet is the fades articularls calcanea anterior, and it
supports the head of the astragalus. The more posteriorly situated facet is the
fades articularis calcanea media. It articulates with the middle facet on the
under surface of the astragalus. The internal articular surface is supported on
a projecting process of bone, called the lesser process of the calcaneus (sustcn-
taculum tali] ; if is also oblong, concave longitudinally, and sometimes subdivided
into two parts, which dift'er in size and shape. More anteriorly is seen the upper
surface of the greater process of the calcaneus, marked by a rough depression
for the attachment of numerous ligaments, and a tubercle for the origin of the
Extensor brevis digitorum muscle.
A
Peroneal tubercle.
Groove for
Peroneus brevis.
Groove for ^^^^f^^For tendo
Peroneus longus. Tubercle for ext. lat. lig. Achillis.
For astragalus.
Sustentaciilum For cuboid.
/ tali.
Groore for Flex,
long, hallucis.
FIG. 177. — The left calcaneus. A. Postero-external view. B. Antero-internal view.
Inferior Surface. — The inferior surface is narrow, rough, uneven, wider behind
than in front and convex from side to side; it is bounded posteriorly by two tuber-
cles separated by a rough depression; the external tubercle (processus lateralis tuber is
calcanei), small, prominent, and rounded, gives attachment to part of the Abductor
minimi digiti : the internal tubercle (processus medialis tuberis calcanei) , broader
and larger, for the support of the heel, gives attachment, by its prominent inner
margin, to the Abductor hallucis, and in front to the Flexor brevis digitorum
muscles and plantar fascia; the depression between the tubercles gives attach-
ment to the Abductor minimi digiti. The rough surface in front of the tubercles
gives attachment to the long plantar ligament and to the outer head of the Flexor
accessorius muscle; while to a prominent tubercle nearer the anterior part of
246 THE SKELETON
this surface, as well as to a transverse groove in front of it, is attached the
short plantar ligament.
External Surface. — The external surface is broad, flat, and almost subcutaneous;
it presents near its centre a tubercle, for the attachment of the middle fasciculus
of the external lateral ligament. At its upper and anterior part this surface
gives attachment to the external calcaneo-astragaloid ligament; and in front of
the tubercle it presents a narrow surface marked by two oblique grooves, sepa-
rated by an elevated ridge which varies much in size in different bones; it is
named the peroneal spine or tubercle (processus trochlearis) , and gives attachment
to a fibrous process from the external annular ligament. The superior groove
transmits the tendon of the Peroneus brevis; the inferior groove the tendon of
the Peroneus longus.
Internal Surface. — The internal surface is deeply concave; it is directed obliquely
downward and forward, and serves for the transmission of the plantar vessels
and nerves into the sole of the foot; it affords attachment to part of the Flexor
accessorius muscle. At its upper and fore part it presents an eminence of bone,
the lesser process of the calcaneum (sustentaculum tali), which projects horizon-
tally inward, and to it a slip of the tendon of the Tibialis posticus is attached.
This process is concave above, and supports the anterior articular surface of
the astragalus; below, it is grooved for the tendon of the Flexor longus hallucis.
Its free margin is rough, for the attachment of part of the internal lateral liga-
ment of the ankle-joint.
Anterior Surface (fades articularis cuboidea). — The anterior surface, of a some-
what triangular form, articulates with the cuboid. It is concave from above
downward and outward, and convex in the opposite direction. Its inner border
gives attachment to the inferior calcaneo-scaphoid ligament.
Posterior Surface. — The posterior surface is rough, prominent, convex, and
wider below than above. The posterior extremity is the projection of the heel.
It is called the tuberosity (tuber calcanei). Its lower part is rough, for the attach-
ment of the tendo Achillis and the tendon of the Plantaris muscle ; its upper part
is smooth, and is covered by a bursa which separates the tendons from the bone.
Articulations. — With two bones: the astragalus and cuboid.
Attachment of Muscles. — To eight : part of the Tibialis posticus, the tendo
Achillis, Plantaris, Abductor hallucis, Abductor minimi digiti, Flexor brevis digi-
torum, Flexor accessorius, and Extensor brevis digitorum.
The Astragalus, or Ankle Bone (talus) (Fig. 178). — The astragalus (da-pdjaXo;;,
a die) is the largest of the tarsal bones, next to the os calcis. It occupies the
middle and upper part of the tarsus, supporting the tibia above, articulating
with the malleoli on either side, resting below upon the os calcis, and joined in
front to the scaphoid. This bone may easily be recognized by its large rounded
head, by the broad articular facet on its upper convex surface, and by the two
articular facets separated by a deep groove on its under concave surface. It
is divided into a body (corpus tali), which supports the trochlear surface; the
head (caput tali), which is in front of the body; and the neck (collum tali), the
constricted part between the head .and body. The astragalus presents six
surfaces for examination.
Superior Surface. — The superior surface presents, behind, a broad smooth
trochlear surface (trochlea tali) for articulation with the tibia. The trochlea is
broader in front than behind, convex from before backward, slightly concave
from side to side; in front of it is the upper surface of the neck of the
astragalus, rough for the attachment of ligaments.
Inferior Surface. — The inferior surface presents two articular facets separated
by a deep groove (sulcus tali). The groove runs obliquely forward and outward,
becoming gradually broader and deeper in front: it corresponds with a similar
THE TARSUS
247
groove upon the upper surface of the calcaneus, and forms, when articulated with
that bone, a canal (sinus tarsi), filled up in the recent state by the interosseous
calcaneo-astragaloid ligament. Of the two articular facets, the posterior articular
facet (fades articularis calcanea posterior) is the larger, of an oblong form and
deeply concave from side to side; the anterior articular facet is shorter and nar-
rower, of an elongated oval form, convex longitudinally, and often subdivided into
two by an elevated ridge ; of these, the posterior (fades articularis calcanea media)
articulates with the lesser process of the os calcis ; the anterior (fades articularis
calcanea (interior) , with the upper surface of the inferior calcaneo-scaphoid ligament.
Internal Surface. — The internal surface presents at its upper part a pear-shaped
articular facet (fades malleolaris medialis) for the inner malleolus, continuous
above with the trochlear surface; below the articular surface is a rough
depression, for the attachment of the deep portion of the internal lateral ligament.
External Surface. — The external surface presents a large triangular facet (fades
malleolaris lateralis), covered with cartilage and concave from above downward
for
navicular. Neck.
Sup. surface
for tibia.
For inner
malleolus.
For navicular.
For ext.-
malleolus.
^For inferior
calc. name. lig.
Groove for
Flex. long. hall.
FIG. 178. — The left astragalus. A. Superior and external view. B. Inferior and internal view.
for articulation with the external malleolus ; it is called the external process (pro-
cessus lateralis tali), and passes outward and downward from the triangular facet.
The triangular facet is continuous above with the trochlear surface; and in front
of it is a rough depression for the attachment of the anterior fasciculus of the
external lateral ligament of the ankle-joint.
Anterior Surface (fades articularis navicularis) . — The anterior surface of the
head of the astragalus is convex and rounded, smooth, of an oval form, and
directed obliquely inward and downward; it articulates with the scaphoid. On
its under and inner surface is a small facet, continuous in front with the articular
surface of the head, and behind with the smaller facet for the os calcis. This
rests on the inferior calcaneo-scaphoid ligament, being separated from it by the
sy no vial membrane, which is prolonged from the anterior calcaneo-astragaloid
joint to the astragalo-scaphoid joint. The head is surrounded by a constricted
portion, the neck of the astragalus (collum tali).
Posterior Surface. — The posterior surface is narrow, and traversed by a groove
(sulcus m. ftexoris halluds longi), which runs obliquely downward and inward,
and transmits the tendon of the Flexor longus hallucis, external to which is
the prominent external tubercle (processus posterior tali), to which the posterior
fasciculus of the external lateral ligament is attached. This tubercle is some-
times separated from the rest of the astragalus, and is then known as the os
trigonum. To the inner side of the groove is the less marked internal tubercle.
To ascertain to which foot the bone belongs, hold it with the broad articular
surface upward, and the rounded head forward; the lateral triangular articular
surface for the external malleolus will then point to the side to which the bone
belongs.
248
THE SKELETON
Articulations. — With four bones: tibia, fibula, os calcis, and scaphoid.
The Cuboid (os cuboideum) (Fig. 179). — The cuboid, from xu/9oc, a cube;
tidos, like, is placed on the outer side of the foot, in front of the os calcis, and
For ext.
cuneiform.
For fourth
metatarsal.
Occasional facet
for navicular.
Groove for
Peroneus longus. For os calcis.
For fifth metatarsal.
FIG. 179. — The left cuboid. A. Antero-internal view. B. Postero-external view.
behind the fourth and fifth metatarsal bones. It is of a pyramidal shape, its
base being directed inward, its apex outward. It may be distinguished from
the other tarsal bones by the existence of a deep groove on its under surface,
for the tendon of the Peroneus longus muscle. It presents for examination six
surfaces: three articular and three non-articular.
Non-articular Surfaces. — The non-articular surfaces are the superior, inferior, and
external. The superior or dorsal surface, directed upward and outward, is rough,
for the attachment of numerous ligaments. The inferior or plantar surface presents
in front a deep groove, the peroneal groove (sulcus m. peronoei longi), which
runs obliquely from without, forward and inward ; it lodges the tendon of the
Peroneus longus, and is bounded behind by a prominent ridge, to which is
attached the long calcaneo-cuboid ligament. The ridge terminates externally
in an eminence, the tuberosity of the cuboid (tuberositas ossis cuboidei), the sur-
face of which presents a convex facet, for articulation with the sesamoid bone
of the tendon contained in the groove. The surface of bone behind the groove
is rough, for the attachment of the short plantar ligament, a few fibres of the
Flexor brevis hallucis, and a fasciculus from the tendon of the Tibialis posticus.
The external surface, the smallest and narrowest of the three, presents a deep
notch formed by the commencement of the peroneal groove.
Articular Surfaces. — The articular surfaces are the posterior, anterior, and
internal. The posterior surface is smooth, triangular, and concavo-conyex, for
articulation with the anterior surface of the os calcis. The anterior surface, of
smaller size, but also irregularly triangular, is divided by a vertical ridge into
two facets; the inner one, quadrilateral in form, articulates with the fourth
metatarsal bone; the outer one, larger and more triangular, articulates with
the fifth metatarsal. The internal surface is broad, rough, irregularly quadri-
lateral, presenting at its middle and upper part a smooth oval facet, for articula-
tion with the external cuneiform bone; and behind this (occasionally) a smaller
facet, for articulation with the navicular; it is rough in the rest of its extent, for
the attachment of strong interosseous ligaments. .
To ascertain to which foot the bone belongs, hold it so that its under surface,
marked by the peroneal groove, looks downward, and the large concavo-convex
articular surface backward toward the holder: the narrow non-articular surface,
marked by the commencement of the peroneal groove, will point to the side to
wrhich the bone belongs.
Articulations. — With four bones: 'the os calcis, external cuneiform, and the
fourth and fifth metatarsal bones; occasionally with the scaphoid.
Attachment of Muscles. — Part of the Flexor brevis hallucis and a slip from
the tendon of the Tibialis posticus.
THE TARSUS
249
Scaphoid or Navicular Bone (os naviculare pedis) (Fig. 180). — The scaphoid
is situated at the inner side of the tarsus, between the astragalus behind and
For mid. cuneiform.
For int. /
For ext.
/cuneiform.
For cuboid
(occasional). For attragalua,
FIG. 180. — The left scaphoid. A. Antero-external view. B. Postero-internal view.
the three cuneiform bones in front. It may be distinguished by its form, being
concave behind, convex and subdivided into three facets in front.
Surfaces. — The anterior surface, of an oblong form, is convex from side to side,
and subdivided by two ridges into three facets, for articulation with the three
cuneiform bones. The posterior surface is oval, concave, broader externally
than internally, and articulates with the rounded head of the astragalus. The
superior surface is convex from side to side, and rough for the attachment of
ligaments. The inferior is irregular, and also rough for the attachment of liga-
ments. The internal surface presents a rounded tubercular eminence, the
tuberosity (tuberositas ossis navicularis) , the lower part of which projects, and
gives attachment to part of the tendon of the Tibialis posticus. The external
surface is rough and irregular, for the attachment of ligamentous fibres, and
occasionally presents a small facet for articulation with the cuboid bone.
To ascertain to which foot the bone belongs, hold it with the concave articular
surface backward, and the convex dorsal surface upward; the external surface —
i. e., the surface opposite the tubercle — will point to the side to which the bone
belongs.
Articulations. — With four bones: astragalus and three cuneiform; occasionally
also with the cuboid.
Attachment of Muscles. — Part of the Tibialis posticus.
Cuneiform or Wedge Bones. — The cuneiform bones have received their
name from their wedge-like shape (cuneus, a wedge; forma, likeness). They
form, with the cuboid, the anterior row
of the tarsus, being placed between the
scaphoid behind, the three innermost
metatarsal bones in front, and the cu-
boid externally. They are called the
first, second, and third, counting from
the inner to the outer side of the foot,
and, from their position, internal, mid-
dle, and external.
Internal or First Cuneiform (os
cuneiforme primum) (Fig. 181). — The
internal cuneiform is the largest of the ^r tendon of
three. It is situated at the inner side
of the foot, between the scaphoid behind
and the base of the first metatarsal in front. It may be distinguished from the
other two by its large size, and by its not presenting such a distinct wedge-like
form. Without the others it may be known by the large, kidney-shaped anterior
For middle
cuneiform.
For navicular.
FIG. 181. — The left internal cuneiform. A, Antero-
internal view. B, Postero-external view.
250
THE SKELETON
articulating surface and by the prominence on the inferior or plantar surface for
the attachment of the Tibialis posticus. It presents for examination six surfaces.
Surfaces. — The internal surface is subcutaneous, and forms part of the inner
border of the foot; it is broad, quadrilateral, and presents at its anterior inferior
angle a smooth oval facet, into which the tendon of the Tibialis anticus is
partially inserted; in the rest of its extent it is rough, for the attachment of
ligaments. The external surface is concave, presenting, along its superior and
posterior borders, a narrow, reversed, L-shaped surface, for articulation with the
middle cuneiform behind and second metatarsal bone in front; in the rest of its
extent it is rough, for the attachment of ligaments and part of the tendon of the
Peroneus longus. The anterior surface, kidney-shaped, much larger than the poste-
rior, articulates with the metatarsal bone of the great toe. The posterior surface
is triangular, concave, and articulates with the innermost and largest of the three
facets on the anterior surface of the scaphoid. The inferior or plantar surface
is rough, and presents a prominent tuberosity at its back part for the attachment
of part of the tendon of the Tibialis posticus. It also gives attachment in front
to part of the tendon of the Tibialis anticus. The superior surface is the narrow-
pointed end of the wedge, which is directed upward and outward; it is rough
for the attachment of ligaments.
To ascertain to which side the bone belongs, hold it so that its superior narrow
edge looks upward, and the long, kidney-shaped, articular surface forward; the
external surface, marked by its vertical and horizontal articular facets, will
point to the side to which it belongs.
Articulations. — With four bones: scaphoid, middle cuneiform, first and second
metatarsal bones.
Attachment of Muscles. — To three : the Tibialis anticus and posticus, and
Peroneus longus.
Middle or Second Cuneiform (os cuneiforme secundum) (Fig. 182). — The
middle cuneiform, the smallest of the three, is of very regular wedge-like form,
the broad extremity being placed upward, the narrow end downward. It is
situated between the other two bones of the same name, and articulates with the
scaphoid behind and the second metatarsal in front. It is smaller than the external
cuneiform bone, from which it may be further distinguished by the L-shaped
articular facet, which runs round the upper and back part of its inner surface.
For int. cuneiform
For navicular.
1
For navicular.
For mid. cuneiform.
For fourth For cuboid,
metatarsal.
For For third
second metatarsal. metatarsal.
FIG. 182. — The left middle cuneiform. A. Antero- FIG. 183. — The left external cuneiform. A. Postero-internal
internal view. B. Postero-external view. view. B. Antero-external view.
Surfaces. — The anterior surface, triangular in form and narrower than the poste-
rior, articulates with the base of the second metatarsal bone. The posterior sur-
face, also triangular, articulates with the scaphoid . The internal surface presents
a reversed L-shaped articular facet, running along the superior and posterior
borders, for articulation with the internal cuneiform, and is rough in the rest
of its extent, for the attachment of ligaments. The external surface presents
posteriorly a smooth facet for articulation with the external cuneiform bone.
The superior surface forms the base of the wedge; it is quadrilateral, broader
behind than in front, and rough for the attachment of ligaments. The inferior
THE TARSUS 251
surface, pointed and tubercular, is also rough for ligamentous attachment and
for the insertion of a slip from the tendon of the Tibialis posticus.
To ascertain to which foot the bone belongs, hold its superior or dorsal surface
upward, the broadest edge being toward the holder: the smooth facet (limited
to the posterior border) will then point to the side to which it belongs.
Articulations. — With four bones: scaphoid, internal and external cuneiform,
and second matatarsal bone.
Attachment of Muscles. — A slip from the tendon of the Tibialis posticus is
attached to this bone.
External or Third Cuneiform (os cuneiforme tertium) (Fig. 183). — The exter-
nal cuneiform, intermediate in size between the two preceding, is of a very
regular wedge-like form, the broad extremity being placed upward, the narrow
end downward. It occupies the centre of the front row of the tarsus, between
the middle cuneiform internally, the cuboid externally, the scaphoid behind, and
the third metatarsal in front. It is distinguished from the internal cuneiform
bone by its more regular wedge-like shape and by the absence of the kidney-
shaped articular surface: from the middle cuneiform, by the absence of the
reversed L-shaped facet, and by the two articular facets which are present on
both its inner and outer surfaces. It has six surfaces for examination.
Surfaces. — The anterior surface, triangular in form, articulates with the third
metatarsal bone. The posterior surface articulates with the most external facet
of the scaphoid, and is rough below for the attachment of ligamentous fibres.
The internal surface presents two articular facets, separated by a rough depres-
sion ; the anterior one, sometimes divided into two, articulates with the outer side
of the base of the second metatarsal bone; the posterior one skirts the posterior
border and articulates with the middle cuneiform; the rough depression between
the two gives attachment to an interosseous ligament. The external surface also
presents two articular facets, separated by a rough non-articular surface; the
anterior facet, situated at the superior angle of the bone, is small, and articulates
with the inner side of the base of the fourth metatarsal; the posterior and larger
one articulates with the cuboid; the rough, non-articular surface serves for the
attachment of an interosseous ligament. The three facets for articulation with
the three metatarsal bones are continuous with one another, and covered by a
prolongation of the same cartilage; the facets for articulation with the middle
cuneiform and scaphoid are also continuous, but that for articulation with he
cuboid is usually separate. The superior or dorsal surface is of an oblong square
form, its posterior external angle being prolonged backward. The inferior or
plantar surface is an obtuse rounded margin, and serves for the attachment of
part of the tendon of the Tibialis posticus, part of the Flexor brevis hallucis,
and ligaments.
To ascertain to which side the bone belongs, hold it with the broad dorsal
surface upward, the prolonged edge backward; the separate articular facet for
the cuboid will point to the proper side.
Articulations. — With six bones: the scaphoid, middle cuneiform, cuboid, and
second, third, and fourth metatarsal bones.
Attachment of Muscles. — To two: part of the Tibialis posticus, and Flexor
brevis hallucis.
The number of tarsal bones may be reduced owing to congenital ankylosis
which may occur between the os calcis and cuboid, the os calcis and scaphoid,
the os calcis and astragalus, or the astragalus and scaphoid.
252
THE SKELETON
The Metatarsal Bones (Ossa Metatarsalia).
The metatarsal bones are five in number, and are numbered one to five, in
accordance with their position from within outward; they are long bones, and
present for examination a shaft and two extremities.
Common Characters. — The shaft (corpus) is prismoid in form, tapers gradually
from the tarsal to the phalangeal extremity, and is slightly curved longitudinally,
so as to be concave below, slightly convex above. On the plantar surface of the
shaft of each bone is a nutrient foramen corresponding to the nutrient foramen
in each metacarpal bone. The posterior or proximal extremity, or base (basis) ,
is wedge-shaped, articulating by its terminal surface with the tarsal bones, and
by its lateral surfaces with the contiguous metatarsal bones, its dorsal and plantar
surfaces being rough for the attachment of ligaments. The anterior or distal
extremity, or head (capitulum) , presents a terminal rounded articular surface,
oblong from above downward, and extending farther backward below than
above. Its sides are flattened and present a depression, surmounted by a
tubercle, for ligamentous attachment. Its under surface is grooved in the
middle line for the passage of the Flexor tendon, and marked on each side by
an articular eminence continuous with the terminal articular surface.
Peculiar Characters. First Metatarsal Bone or the Metatarsal Bone of the Great
Toe (os metatarsale I) . — The first (Fig. 184) is remarkable for its great thickness,
but is the shortest of all the metatarsal bones. The shaft is strong and of well-
marked prismoid form. The posterior extremity presents, as a rule, no lateral
articular facet, but occasionally on the outer side there is an oval facet by which
it articulates with the second metatarsal bones. Its terminal articular surface is of
large size and kidney-shaped; its circumference is grooved, for the tarso-metatarsal
ligaments, and internally gives attachment to part of the tendon of the Tibialis
anticus muscle; its inferior angle presents a rough oval prominence, the tuberosity
(tuberositas ossis metatarsalis I), for the insertion of the tendon of the Peroneus
longus. The head is of large size; on its plantar surface are two grooved facets,
over which glide sesamoia bones ; the facets are separated by a smooth elevated
ridge.
This bone is known by the single kidney-shaped articular surface on its base,
the deeply grooved appearance of the plantar surface of its head, and its great
thickness relatively to its length.
When it is placed in its natural
position, the concave border of
the kidney-shaped articular sur-
face on its base points to the
side to which the bone belongs.
Attachment of Muscles. — To
three: part of the Tibialis anti-
cus, the Peroneus longus, and
the First dorsal interosseous.
Second Metatarsal (os metatar-
sale II).— The second (Fig. 185)
is the longest and largest of the
remaining metatarsal bones, be-
ing prolonged backward into the
recess formed between the three
cuneiform bones. Its tarsal ex-
tremity is broad above, narrow
and rough below. It presents
four articular surfaces: one be-
Occasional facet for
second metatarsal.
For internal cuneiform.
FIG. 184.— The first metatarsal. (Left.)
THE METATARSAL BONES
253
hind, of a triangular form, for articulation with the middle cuneiform; one at the
upper part of its internal lateral surface, for articulation with the internal cunei-
Occasionnl
facet for first
metatarsal. For
For middle cuneiform.
FIG. 185. — The second metatarsal. (Left.)
For second metnlarsal.
For middle cuneiform.
For fourth
metatarsal.
FIG. 186. — The third metatarsal. (Left.)
form ; and two on its external lateral surface — an upper and a lower, separated by
a rough non-articular interval. Each of these articular surfaces is divided by a
vertical ridge into two facets, thus making four facets; the two anterior of these
articulate with the third metatarsal ; the two posterior (sometimes continuous) with
the external cuneiform. In addition to these articular surfaces there is occasion-
ally a fifth when this bone articulates with the first metatarsal bone. It is oval in
shape, and is situated on the inner side of the shaft near the base.
The facets on the tarsal extremity of the second metatarsal bone serve at once
to distinguish it from the rest, and to indicate the foot to which it belongs; there
being one facet at the upper angle of the internal surface, and two facets, each
subdivided into two parts, on the external surface, pointing to the side to which
the bone belongs. The fact that the two posterior subdivisions of these external
facets sometimes run into one should not be forgotten.
Attachment of Muscles. — To four: the Adductor obliquus hallucis, First and
Second dorsal interosseous, and a slip from the tendon of the Tibialis posticus;
occasionally also a slip from the Peroneus longus.
Third Metatarsal (os metatarsale III) . — The third metatarsal (Fig. 186) articu-
lates behind, by means of a triangular smooth surface, with the external cunei-
form; on its inner side, by two facets, with the second metatarsal; and on its
outer side, by a single facet, with the fourth metatarsal. The latter facet is of
circular form and situated at the upper angle of the base.
The third metatarsal is known by its having at its tarsal end two undivided
facets on the inner side, and a single facet on the outer. This distinguishes it
from the second metatarsal, in which the two facets, found on one side of its
tarsal end, are each subdivided into two. The single facet (when the bone is put
in its natural position) is on the side to which the bone belongs.
Attachment of Muscles. — To five : Adductor obliquus hallucis, Second and
Third dorsal, and First plantar interosseous, and a slip from the tendon of the
Tibialis posticus.
254
THE SKELETON
Fourth Metatarsal (os metatarsale IV}.— The fourth metatarsal (Fig. 187) is
smaller in size than the preceding; its tarsal extremity presents a terminal quad-
For third
metatarsal.
For cuboid.
For ext. cuneiform.
For fifth
metatarsal,.
Tuberosity.
FIG. 187. — The fourth metatarsal. (Left.)
For fourth
metatarsal.
For cuboid.
FIG. 188.— The fifth metatarsal. (Left.)
rilateral surface, for articulation with the cuboid; a smooth facet on the inner
side, divided by a ridge into an anterior portion for articulation with the third
metatarsal, and a posterior portion for articulation with the external cuneiform;
on the outer side a single facet, for articulation with the fifth metatarsal.
The fourth metatarsal is known by its having a single facet on either side of
the tarsal extremity, that on the inner side being divided into two parts. If this
subdivision be not recognizable, the fact that its tarsal end isjbent somewhat
outward will indicate the side to which it belongs.
Attachment of Muscles. — To five: Adductor obliquus hallucis, Third and
Fourth dorsal, and Second plantar interosseous, and a slip from the tendon of the
Tibialis posticus.
Fifth Metatarsal Bone, or the Metatarsal Bone of the Little Toe (os metatarsale V).
—The fifth metatarsal (Fig. 188) is recognized by the tubercle (tuberositas ossis
metatarsalis V) on the outer side of its base. It articulates behind, by a tri-
angular surface cut obliquely from without inward, with the cuboid, and inter-
nally with the fourth metatarsal.
The projection on the outer side of this bone at its tarsal end at once distin-
guishes it from the others, and points to the side to which it belongs.
Attachment of Muscles. — To six : the Peroneus brevis, Peroneus tertius,
Flexor brevis minimi digiti, Adductor trarisversus hallucis, Fourth dorsal, and
Third plantar interossei.
Articulations. — Each bone articulates with the tarsal bones by one extremity,
and by the other with the first row of phalanges. The number of tarsal bones
with which each metatarsal articulates is one for the first, three for the second,
one for the third, two for the fourth, and one for the fifth.
DEVELOPMENT OF THE FOOT 255
The Phalanges of the Foot (Phalanges Digitorum Pedis).
The phalanges of the foot, both in number and general arrangement, resemble
those in the hand; there being two in the great toe and three in each of the
other toes. The nutritive foramina correspond to those in the phalanges of the
hand.
The first or proximal phalanx (phalanx prima) resembles closely the correspond-
ing bone of the hand. The shaft also is compressed from side to side, convex
above, concave below. The posterior extremity is concave; and the anterior
extremity presents a trochlear surface, for articulation with the second phalanx.
The second phalanx (phalanx secunda) is remarkably small and short, but
rather broader than the first phalanx.
The ungual or distal phalanx (phalanx tertia) in form resembles the bone of the
corresponding finger, but is smaller, flattened from above downward, presenting a
broad base for articulation with the second phalanx, and an expanded extremity
for the support of the nail and end of the toe.
Articulation. — The first row, with the metatarsal bones behind and second
phalanges in front; the second row of the four outer toes, with the first and third
phalanges; of the great toe, with the first phalanx; the third row of the four outer
toes, with the second phalanges.
Attachment of Muscles. — To the first phalanges. Great toe, five muscles:
innermost tendon of Extensor brevis digitorum, Abductor hallucis, Adductor
obliquus hallucis, Flexor brevis hallucis, Adductor transversus hallucis. Second
toe, three muscles: First and Second dorsal interosseous and First lumbrical.
Third toe, three muscles : Third dorsal and First plantar interosseous and Second
lumbrical. Fourth toe, three muscles: Fourth dorsal and Second plantar inter-
osseous and Third lumbrical. Fifth toe, four muscles: Flexor brevis minimi
digiti, Abductor minimi digiti, and Third plantar interosseous, and Fourth
lumbrical. — Second phalanges. Great toe; Extensor longus hallucis, Flexor
longus hallucis. Other toes; Flexor brevis digitorum, one slip of the common
tendon of the Extensor longus and brevis digitorum.1 — Third phalanges: two slips
from the common tendon of the Extensor longus and Extensor brevis digitorum,
and the Flexor longus digitorum.
Development of the Foot (Fig. 189).
The Tarsal Bones are each developed by a single centre, excepting the os calcis
which has an epiphysis for its posterior extremity. The centres make their appear-
ance in the following order: os calcis, at the sixth month of foetal life; astragalus,
about the seventh month; cuboid, at the ninth month; external cuneiform, dur-
ing the first year; internal cuneiform in the third year; middle cuneiform and
scaphoid in the fourth year. The epiphysis for the posterior tuberosity of the
os calcis appears at the tenth year, and unites with the rest of the bone soon
after puberty.
The Metatarsal Bones are each developed by two centres: one for the shaft
and one for the digital extremity in the four outer metatarsal; one for the shaft
and one for the base in the metatarsal bone of the great toe.2 Ossification com-
mences in the centre of the shaft about the ninth week, and extends toward
either extremity. The centre in the proximal end of the first metatarsal bone
appears about the third year, the centre in the distal end of the other bones
1 Except the second phalanx of the fifth toe, which receives no slip from the Extensor brevis digitorum. —
ED. of 15th English Edition.
2 As was noted in the first metacarpal bone, so in the first metatarsal, there is often to be observed a ten-
dency to the formation of a second epiphysis in the distal extremity. — ED. of 15th English Edition.
256
THE SKELETON
between the fifth and eighth years; they become joined between the eighteenth
and twentieth years.
The Phalanges are developed by two centres for each bone: one for the shaft
and one for the metatarsal extremity. The centre for the shaft appears about the
tenth week, that for the epiphysis between the fourth and tenth years; they join
the shaft about the eighteenth year.
y sis.
Appears 10th year ;
' unites after puberty.
Tarsus.
One centre for each bone,
except os calcis.
Metatarsus.
Two centres for each bone :
One for shaft,
One for digital extremity
except 1st.
Appears 7th week. ~
Unite 18th-20th year.
Appears 3rd year.
Appears 4th year.
Unite 17-18th year, j
Phalanges. Appears 2nd-4th month.-
Two centres for each bone :
One for shaft,
One for metatarsal Appears 6th-7th year.
Appears 5th year.
Unite 18th-20 year.
-Appears 7th week.
extremity.
Unite 17th-18th year.
,.-Cl
Appears 2nd~4th month
Appears 6th year.-^ s (W
Unite 17.th-18th year.-{^ 2
Appears 7th joeefc. — 5J> jj
FIG. 189. — Plan of the development of the foot.
Construction of the Foot as a Whole (Figs. 190, 191).
The foot is constructed on the same principles as the hand, but modified to form
a firm basis of support for the rest of the body when in the erect position. It
is more solidly constructed, and its component parts are less movable on each
other than in the hand. This is especially the case with the great toe, which has
to assist in supporting the body, and is therefore constructed with greater solidity;
it lies parallel with the other toes, and has a very limited degree of mobility,
whereas the thumb, which is occupied in numerous and varied movements, is
constructed in such a manner as to permit of great mobility. Its metacarpal bone
is directed away from the others, so as to form an acute angle with the second,
and it enjoys a considerable range of motion at its articulation with the carpus.
The foot is placed at right angles to the leg — a position which is almost peculiar
to man, and has relation to the erect position which he maintains. In order to
CONSTRUCTION OF THE FOOT AS A WHOLE
257
allow of its supporting the weight of the whole body in this position with the
least expenditure of material, it is constructed in the form of an arch. This
antero-posterior or longitudinal arch is made up of two unequal limbs. The
FIG. 190. — Skeleton of the foot, internal border. (Poirier and Charpy.)
SECOND CUNEIFORM
SECOND MCTATARSAL
FIG. 191. — Skeleton of the foot, external border. (Poirier and Charpy.)
hinder one, which is made up of the os calcis and the posterior part of the
astragalus, is about half the length of the anterior limb, and measures about
three inches. The anterior limb consists of the rest of the tarsal and the meta-
tarsal bones, and measures about seven inches. It may be said to consist of two
parts, an inner segment made up of the head of the astragalus, the scaphoid,
the three cuneiform, and the three inner metatarsal bones; and an outer segment
composed of the os calcis, the cuboid, and the two outer metatarsal bones. The
summit of the arch is at the superior articular surface of the astragalus; and its
two extremities — that is to say, the two piers on which the arch rests in standing
— are the tubercles on the under surface of the os calcis posteriorly, and the heads
of the metatarsal bones anteriorly. The weakest part of the arch is the joint
between the astragalus and scaphoid, and here it is more liable to yield in those
who are overweighted, and in those in whom the ligaments which complete and
preserve the arch are relaxed. This weak point in the arch is braced on its con-
cave surface by the inferior calcaneo-scaphoid ligament, which is more elastic
than most other ligaments, and thus allows the arch to yield from jars or shocks
applied to the anterior portion of the foot and quickly restores it to its pristine
condition. This ligament is supported internally by blending with the Deltoid
ligament, and inferiorly by the tendon of the Tibialis posticus muscle, which is
spread out into a fan-shaped insertion, and prevents undue tension of the ligament
or such an amount of stretching as would permanently elongate it.
In addition to this longitudinal arch the foot presents a transverse arch, at the
anterior part of the tarsus and hinder part of the metatarsus. This, however, can
scarcely be described as a true arch, but presents more the character of a half-
dome. The inner border of the central portion of the longitudinal arch is elevated
17
258 THE SKELETON
from the ground, and from this point the bones arch over to the outer border,
which is in contact with the ground, and, assisted by the longitudinal arch, pro-
duce a sort of rounded niche on the inner side of the foot, which gives the appear-
ance of a transverse as well as a longitudinal arch.
The line of the foot, from the point of the heel to the toes, is not quite straight,
but is directed a little outward, so that the inner border is a little convex and the
outer border concave. This disposition of the bones becomes more marked when
the longitudinal arch of the foot is lost, as in the disease known under the name
of "flat-foot."
Surface Form.— On the dorsum of the foot the individual bones are not to be distinguished
with the exception of the head of the astragalus, which forms a rounded projection in front of
the ankle-joint when the foot is forcibly extended. The whole surface forms a smooth convex
outline, the summit of which is the ridge formed by the head of the astragalus, the scaphoid,
the middle cuneiform, and the second metatarsal bones; from this it gradually inclines outward
and more rapidly inward. On the inner side of the foot, the internal tuberosity of the OS calcis
and the ridge separating the inner from the posterior surface of the bone may be felt most poste-
riorly. In front of this, and below the internal malleolus, may be felt the projection of the
SUStentaculum tali. Passing forward is the well-marked tuberosity of the scaphoid bone, situ-
ated about an inch or an inch and a quarter in front of the internal malleolus. Further toward
the front, the ridge formed by the base of the first metatarsal bone can be obscurely felt, and
from this the shaft of the bone can be traced to the expanded head articulating with the base
of the first phalanx of the great toe. Immediately beneath the base of this phalanx, the internal
sesamoid bone is to be felt. Lastly, the expanded ends of the bones forming the last joint of
the great toe are to be felt. On the outer side of the foot the most posterior bony point is the
outer tuberosity of the os calcis, with the ridge separating the posterior from the outer surface
of the bone. In front of this the greater part of the external surface of the os calcis is subcu-
taneous; on it, below and in front of the external malleolus, may be felt the peroneal ridge, when
this process is present. Farther forward, the base of the fifth metatarsal bone forms a prom-
inent and well-defined landmark, and in front of this the shaft of the bone, with its expanded
head, and the base of the first phalanx may be defined. The sole of the foot is almost entirely
covered by soft parts, so that but few bony parts are to be made out, and these somewhat
obscurely. The hinder part of the under surface of the os calcis and the heads of the metatarsal
bones, with the exception of the first, which is concealed by the sesamoid bones, may be recog-
nized.
Surgical Anatomy. — Considering the injuries to which the foot is subjected, it is surpris-
ing how seldom the tarsal bones are fractured. This is no doubt due to the fact that the tarsus
is composed of a number of bones, articulated by a considerable extent of surface and joined
together by very strong ligaments, which serve to mitigate the intensity of violence applied to this
part of the body. When fracture does occur, these bones, being composed for the most part
of a soft cancellous structure, covered only by a thin shell of compact tissue, are often extensively
comminuted, especially as most of the fractures are produced by direct violence. As the bones
have only a very scanty amount of soft parts over them, fractures are very often compound, and
amputation is frequently necessary.
When fracture occurs in the anterior group of tafsal bones, it is almost invariably the result
of direct violence; but fractures of the posterior group, that is, of the calcaneum and astrag-
alus, are most frequently produced by falls from a height on to the feet; though fracture of the
os calcis may be caused by direct violence or by muscular action. The posterior part of the
bone, that is, the part behind the articular surfaces, is almost always the seat of the fracture,
though some few cases of fracture of the sustentaculum tali and of vertical fracture between
the two articulating facets have been recorded. The neck of the astragalus, being the weakest
part of the bone, is most frequently fractured, though fractures may occur in any part and
almost in any direction, either associated or not with fracture of other bones.
In cases of club-foot, especially in congenital cases, the bones of the tarsus become altered
in shape and size, and displaced from their proper positions. This is especially the case in con-
genital equino-varus, in which the astragalus, particularly about the head, becomes twisted and
atrophied, and a similar condition may be present in the other bones, more especially the sca-
phoid. The tarsal bones are peculiarly liable to become the seat of tuberculous caries, and this
condition may arise after comparatively trivial injuries. There are several reasons to account
for this. They are composed of a delicate cancellated structure, surrounded by intricate synovial
membranes. They are situated at the farthest point from the central organ of the circulation
and exposed to vicissitudes of temperature; and, moreover, on their dorsal surface are thinly
clad with soft parts which have but a scanty blood-supply. And finally, after slight injuries,
they are not maintained in a condition of rest to the same extent as structures suffering from
SESAMOID BONES 259
similar injuries in some other parts of the body. Caries of the calcaneus or astragalus
may remain limited to the one bone for a long period, but when one of the other bones is
affected, the remainder frequently become involved, in consequence of the disease spreading
through the large and complicated synovial membrane which is more or less common to these
bones.
Amputation of the whole or a part of the foot is frequently required either for injury or
disease. The principal amputations are as follows: (1) Syme's : amputation at the ankle-joint
by a heel-flap, with removal of the malleoli and a thin slice from the lower end of the tibia.
(2) Roux's : amputation at the ankle-joint by a large internal flap. (3) Pirogofi's amputa-
tion : removal of the whole of the tarsal bones, except the posterior part of the os calcis.. A thin
slice is sawn from the tibia and fibula, including the two malleoli. The sawn surface of the os
calcis is then turned up and united to the similar surface of the tibia. (4) Subastragaloid
amputation : removal of the foot below the astragalus through the joint between it and the os
calcis. This operation has been modified by Hancock, who leaves the posterior third of the os
calcis and turns it up against the denuded surface of the astragalus. This latter operation is of
doubtful utility and is rarely performed. (5) Chopart's or medio-tarsal : removal of the ante-
rior part of the foot with all the tarsal bones except the os calcis and astragalus; disarticula-
tion being effected through the astragalo-scaphoid and calcaneo-cuboid joints. (6) Lisfranc's :
amputation of the anterior part of the foot through the tarso-metatarsal joints. This was
modified by Hey, who disarticulated through the joints of the four outer metatarsal bones with
the tarsus, and sawed off the projecting internal cuneiform ; and by Skey, who sawed off the base
of the second metatarsal bone and disarticulated the others.
The bones of the tarsus occasionally require removal individually. This is especially the
case with the astragalus and os calcis for disease limited to the one bone, or again the astragalus
may require excision in cases of subastragaloid dislocation, or, as recommended by M.r Lund,
in cases of inveterate talipes. The cuboid has been removed for the same reason by Mr. Solly.
But the latter two operations have fallen into disuse, and have been superseded by resection
of a wedge-shaped piece of bone from the outer side of the tarsus. Finally, Mickulicz and
Watson have devised operations for the removal of more extensive portions of the tarsus.
Mickulicz's operation consists in the removal of the os calcis and astragalus, along with the
articular surfaces of the tibia and fibula, and also of the scaphoid and cuboid. The remain-
ing portion of the tarsus is then brought into contact with the sawn surfaces of the tibia and
fibula, and fixed there. The result is a position of the shortened foot resembling talipes
equinus. Watson's operation is adapted to those cases where the disease is confined to the
anterior tarsal bones. By two lateral incisions he saws through the bases of the metatarsal
bones in front and opens up the joints between the scaphoid and astragalus, and the cuboid and
os calcis, and removes the intervening bones.
Fractures of the metatarsal bones and phalanges are nearly always due to direct violence, and
in many cases the injury is the result of severe crushing accidents, necessitating amputation.
The metatarsal bones, and especially the metatarsal bone of the great toe, are frequently dis-
eased, either in tuberculous subjects or in perforating ulcer of the foot.
Sesamoid Bones (Ossa Sesamoidea) (Figs. 192, 193).
These are small rounded masses, cartilaginous in early life, osseous in the adult,
which are developed in those tendons which exert a great amount of pressure upon
the parts over which they glide. It is said that they are more commonly found in
the male than in the female, and in persons of an active muscular habit than in
those who are weak and debilitated. They are invested throughout their whole
surface by the fibrous tissue of the tendon in which they are found, excepting upon
that side which lies in contact with the part over which they play, where they
present a free articular facet. They may be divided into two kinds: those which
glide over the articular surfaces of the joints, and those which play over the cartilag-
inous facets found on the surfaces of certain bones.
The sesamoid bones of the joints in the upper extremity are two on the palmar
surface of the metacarpo-phalangeal joint in the thumb, developed in the tendons
of the Flexor brevis pollicis; one on the palmar surface of the interphalangeal
joint of the thumb; occasionally one or two opposite the metacarpo-phalangeal
articulations of the fore and little fingers; and, still more rarely, one opposite
the same joints of the third and fourth fingers. In the lower extremity, the
patella, which is developed in the tendon of the Quadriceps extensor; two
small sesamoid bones, found in the tendons of the flexor brevis hallucis, opposite
260
THE SKELETON
the metatarso-phalangeal joint of the great toe ; one sometimes over the inter-
phalangeal joint of the great toe; and occasionally one in the metatarso-phalan-
•geal joint of the second toe, the little toe, and, still more rarely, the third and
fourth toes.
FIG. 192. — Sesamoid bones of the hand,
and Charpy.)
(Poirier
FIG. 193. — Sesamoid bones of the
foot. (Poirier and Charpy.)
Those found in the tendons which glide over certain bones occupy the following
situations: one sometimes found in the tendon of the Biceps cubiti, opposite the
tuberosity of the radius : one in the tendon of the Peroneus longus, where it glides
through the groove in the cuboid bone; one appears late in life in the tendon of the
Tibialis anticus, opposite the smooth facet of the internal cuneiform bone; one is
found in the tendon of the Tibialis posticus, opposite the inner side of the head
of the astragalus; one in the outer head of the Gastrocnemius, behind the outer
condyle of the femur; and one in the conjoined tendon of the Psoas and Iliacus,
where it glides over the os pubis. Sesamoid bones are found occasionally in the
tendon of the Gluteus maximus, as it passes over the great trochanter, and in
the tendons which wind round the inner and outer malleoli.
THE ARTICULATIONS OR JOINTS.
THE various bones of which the Skeleton consists are connected together at
different parts of their surfaces, and such a connection is designated by the
name of joint or articulation. Arthrology is the branch of anatomy which treats of
the joints. Certain joints are immovable, as those between the cranial bones and
most of those between the facial bones. In an immovable joint the adjacent
margins of the bones are applied in almost close contact, a thin layer of fibrous
membrane, the sutural ligament, or, as at the base of the skull, in certain situa-
tions, a thin layer of cartilage, being interposed. Where slight movement is
required, combined with great strength, the osseous surfaces are united by tough
and elastic fibro-cartilages, as in the joints between the vertebral bodies and in the
interpubic articulation; but in the movable joints the bones forming the articula-
tion are generally expanded for greater convenience of mutual connection, covered
by cartilage, held together by strong bands or capsules of fibrous tissue called liga-
ments, and partially lined by a membrane, the synovial membrane, which secretes
a fluid to lubricate the various parts of which the joint is formed; so that the
structures which enter into the formation of a joint are bone, cartilage, fibro-
cartilage, ligament, and synovial membrane.
Bone. — Bone constitutes the fundamental element of all the joints. In the
long bones the extremities are the parts which form the articulations; they are
generally somewhat enlarged and consist of spongy, cancellous tissue, with a thin
coating of compact substance. The layer of compact bone which forms the
articular surface, and to which the cartilage is attached, is called the articular
lamella. It is of a white color, extremely dense, and varies in thickness. Its
structure differs from ordinary bone-tissue in this respect, that it contains no
Haversian canals, and its lacunae are much larger than in ordinary bone and
have no canaliculi. The vessels of the cancellous tissue, as they approach the
articular lamella, turn back in loops, and do not perforate it; this layer is conse-
quently more dense and firmer than ordinary bone, and is evidently designed to
form a firm and unyielding support for the articular cartilage. In the flat bones
the articulations usually take place at the edges, and, in the short bones, at various
parts of their surface.
Cartilage. — Cartilage is material which is a transition stage of connective tissue
into bone. When boiled it yields chondrin. Cartilage is not vascular and is found
in various parts of the body; in adult life chiefly in the joints, in the parietes of
the thorax, and in various tubes, which are to be kept permanently open, such as
the air passages, nostrils, and ears. In the foetus at an early period the greater
part of the skeleton is cartilaginous. Because this cartilage is replaced by bone,
it is called temporary in contradistinction to that which remains unossified during
life, and which is called permanent. Unless active growth is in progress or cal-
cification is going on, cartilage does not contain blood-vessels; if there is either
active growth or calcification it may contain them. The investing membrane of
cartilage is called the perichondrium. It consists of connective-tissue fibres and
a few elastic fibres. The perichondrium carries blood-vessels, which may grow
into the cartilage during active growth or ossification. Cartilage is divided into:
1. Hyaline cartilage. 2. Elastic cartilage. 3. Fibro-cartilage.
The cells of these three varieties of cartilage are similar.
(261)
262
Hyaline Cartilage. — This structure is found in embryos in regions where bone
is to be formed, in the nose, larynx, trachea, bronchi, .and in symphyses, epi-
physes, and synchondroses. Costal cartilage and epiphyseal cartilage are com-
posed of it, and as articular cartilage (cartilago articularis) it covers joint surfaces.
It is a bluish or pearly hued substance, in reality a modified connective tissue,,
but much harder than most connective tissues. The investing membrane, the
perichondrium, is composed chiefly of connective-tissue fibres, although a few elastic
fibres are present. The peripheral layers of the cartilage pass into the perichon-
drium. The perichondrium carries blood-vessels which may, if there be active
growth or ossification in progress, grow down into the cartilage. During growth
the fibres of connective tissue may become the ground substance of cartilage and
the cells of connective tissue may become cartilage cells; hence, the connective-
tissue cells of the perichondrium are called chondroblasts.
Hyaline cartilage is composed of round or oval cells and intercellular substance.
Each cell contains granular protoplasm and a nucleus, and the nucleus contains
one or two nucleoli. The cells are placed in the so-called cartilage spaces of the
ground substance, and the ground substance immediately surrounding a space is
called a cartilage capsule. The cells are placed in groups and near the surface are
arranged in rows, and in some regions are flattened by pressure. The intercellular
or ground substance (matrix) is an apparently homogeneous and structureless
material between the cartilage spaces. By certain methods, however, fibrils can
be demonstrated in it. These fibrils in general are parallel. In some of the
lower animals canals have been demonstrated. In man it has not been proved
that canals exist, and it has been suggested that the fibrils act as paths for the
conduction of nutritive fluid.
Articular cartilage forms a thin incrustation upon the joint-surfaces of the bones,
and its elasticity enables it to break the force of any concussion, while its smooth-
ness affords ease and freedom of movement. It varies in thickness according
to the shape of the articular surface on which it lies; where this is convex the
cartilage is thickest at the centre, where the greatest pressure is received; and the
reverse is the case on the concave articular surfaces. Articular cartilage appears
to derive its nutriment partly from the vessels of the neighboring synovial mem-
brane and partly from those of the bone upon which it is implanted. Toynbee
has shown that the minute vessels of the cancellous tissue as they approach the
articular lamella dilate and form arches, and then return into the substance of
the bone.
The hyaline cartilages, especially in adult and advanced life, are prone to
calcify — that is to say, to have their matrix permeated by the salts of lime without
any appearance of true bone. The process of calcification occurs also, and still
more frequently, according to Rollett, in such cartilages as those of the trachea
and in the costal cartilages, which are prone afterward to conversion into true
bone. The ossification may occur in old age.
Elastic Cartilage. — In this structure there are elastic fibres in the matrix, which
fibres at the periphery of the cartilage enter into the perichondrium. Such carti-
lage is not blue-white in color, but is a very light yellow, and is not to be regarded
as identical with elastic fibrous tissue. Elastic cartilage is found in the epiglottis,
the external ear, the Eustachian tube, the vocal processes of the arytenoid carti-
lages, the corniculate and cuneiform cartilages, and the cartilages of the larynx.
Fibro-cartilage is composed of white fibrous tissue and cartilage in varying pro-
portions ; it is to the first of these two constituents that its flexibility and toughness
are chiefly owing, and to the latter its elasticity ; the cells are fewer in number, but
are possessed of more definite capsules than are those of hyaline cartilage, and they
are usually arranged in groups surrounded by small islands of hyaline matrix,
which may be concentrically striated. The hyaline islands are separated from
CARTILAGE 263
one another by bundles of white fibrous tissue that pursue a markedly wavy
course.
Fibro-cartilage is found at the point of insertion of the ligamentum teres into
the head of the femur, in the intervertebral disks, in the pubic symphysis, and in
the interarticular cartilages.
The fibro-cartilages admit of arrangement into four groups: interarticular, con-
necting, circumferential, and stratiform.
1. The interarticular fibro-cartilages (menisci interarticulares} are flattened,
fibre-cartilaginous plates, of a round, oval, triangular, or sickle-like form, inter-
posed between the articular cartilages of certain joints. They are free on both
surfaces, thinner toward their centre than at their circumference, and held in
position by the attachment of their margins and extremities to the surrounding
ligaments. The synovial membrane of the joint is prolonged over them a short
distance from their attached margins. They are found in the temporo-mandib-
ular, sterno-clavicular, acromio-clavicular, wrist- and knee-joints. These carti-
lages are usually found in those joints which are most exposed to violent concussion
and subject to frequent movement. Their use is to maintain the apposition of the
opposed surfaces in their various motions; to increase the depth of the articular
surfaces and give ease to the gliding movement; to moderate the effects of great
pressure and deaden the intensity of the shocks to which the parts may be sub-
jected. Humphry has pointed out that these interarticular fibro-cartilages serve
an important purpose in increasing the variety of movements in a joint. Thus,
in the knee-joint there are two kinds of motion — viz., angular movement and
rotation — although it is a hinge-joint, in which, as a rule, only one variety of motion
is permitted; the former movement takes place between the condyles of the femur
and the interarticular cartilage, the latter between the cartilage and the head of
the tibia. So, also, in the temporo-mandibular joint, the upward and downward
movement of opening and shutting the mouth takes place between the fibro-
cartilage and the jaw-bone, the grinding movement between the glenoid cavity
and the fibre-cartilage, the latter moving with the jaw-bone.
Interarticular cartilages may divide the joint into two distinct cavities, as in the
temporo-maxillary articulation. The periphery of an articular cartilage is attached
particularly to the capsule and may also be attached to the non-articular portion
of the bone. The semilunar cartilages of the knee resemble tendon more than
they do cartilage. The fibres are arranged in dense, more or less parallel bundles,
separated by small, scattered hyaline cells, and the disks are attached to the bone
by thin layers of hyaline cartilage.
2. The connecting fibro-cartilages are interposed between the bony surfaces of
those joints which admit of only slight mobility, as between the bodies of the
vertebrae and between the pubic bones. They form disks which adhere closely to
both of the opposed surfaces, and are composed of concentric rings of fibrous
tissue, with cartilaginous laminae interposed, the former tissue predominating
toward the circumference, the latter toward the centre.
3. The circumferential fibro-cartilages consist of a rim of fibro-cartilage, which
surrounds the margin of some of the articular cavities, as the cotyloid cavity of
the hip and the glenoid cavity of the shoulder; they serve to deepen the articular
surface, and to protect its edges.
4. The stratiform fibro-cartilages are those which form a thin coating to osseous
grooves through which the tendons of certain muscles glide. Small masses of
fibro-cartilages are developed also in the tendons of some muscles, where they
glide over bones, as in tendons of the Peroneus longus and the Tibialis posticus.
Ligaments. — Ligaments consist of bands of various forms, serving to connect
together the articular extremities of bones, and are composed mainly of coarse
bundles of very dense white fibrous tissue placed parallel with, or closely inter-
264 THE ARTICULATIONS OR JOINTS
laced with, one another, and presenting a white, shining, silvery aspect. These
bundles are called fasciculi. They are held together by a cement substance
containing cells which resemble those of tendon. A ligament is pliant and
flexible, so as to allow of the most perfect freedom of movement, but it is
strong, tough, and inextensile, so as not readily to yield under the most
severely applied force; it is consequently well adapted to serve as the connecting
medium between the bones. Some ligaments consist entirely of yellow elastic
tissue (elastic -fibrous tissue) , the elastic fibres branching considerably, but main-
taining in general a parallel course. The fibres are in bundles, between which
areolar connective tissue lies. The ligamenta subflava, which connect together
the adjacent arches of the vertebrae in man and the ligamentum nuchae in the
lower animals are composed of yellow elastic tissue. In these cases it will be
observed that the elasticity of the ligament is intended to act as a substitute for
muscular power.
Synovial Membranes. — These membranes are serous in character. Asynovial
membrane consists of loose connecting tissue (subendothelial tissue), containing fat,
vessels, and nerves, its inner surface being lined with a single layer of flat endothelial
cells. The endothelial cells are polyhedral, and each cell possesses a flattened oval
nucleus. The cells are held together by intercellular cement. It is believed by some
that little openings occur at intervals in the intercellular cement, but it is held by
many that the supposed openings are artifacts. Synovial cavities contain a little
fluid. A non-articular synovial membrane does not actually secrete fluid, but it is
moistened by lymph which passes through the membrane and into the cavity by
osmosis.
Joint cavities and bursse communicating with joints contain a characteristic
fluid which is a secretion of the membrane. It is yellowish-white or slightly red-
dish, somewhat cloudy, viscid like the white of an egg, having a strongly alkaline
reaction and a slightly saline taste. It consists of fats, salts, albumins, extract-
ives from lymph, a mucinous body known as synovin,1 and another mucin-like
body, which is rich in phosphorus (Simon). The synovial membranes found
in the body admit of subdivision into three kinds — articular, bursal, and vaginal.
Articular Synovial Membrane. — Articular synovial membrane is found in every
freely movable joint. It lines the capsule of the joint and is reflected upon the
non-articular intrascapular portion of the bones which enter into the formation
of the joint. In the foetus this membrane is said, by Toynbee, to be continued
over the surface of the cartilages; but in the adult it merely encroaches for a short
distance upon the margins of the cartilages, to which it is firmly attached; it
then invests the inner surface of the capsular or other ligaments enclosing the
joint, and is reflected over the surface of any tendons passing through its cavity, as
the tendon of the Popliteus in the knee and the tendon of the Biceps in the shoulder.
Hence the articular synovial membrane may be regarded as a short wide tube,
attached by its open ends to the margins of the articular cartilages, and covering
the inner surface of the various ligaments which connect the articular surfaces,
so that along with the cartilages it completely encloses the joint-cavity. In some
of the joints the synovial membrane is thrown into folds, which pass across the
cavity. They are called synovial ligaments, and are especially distinct in the knee.
These folds, when large, frequently contain considerable quantities of fat, which
acts as a cushion between the two articular surfaces and which serves a valuable
purpose in filling up gaps. In some joints there are flattened folds, subdivided
at their margins into fringe-like processes (synovial villi), the vessels of which
have a convoluted arrangement. These latter generally project from the synovial
membrane near the margin of the cartilage and lie flat upon its surface. They
consist of connective tissue covered with endothelium, and contain fat-cells in
variable quantities, and, more rarely, isolated cartilage-cells. They were described
1 Simon's Physiological Chemistry.
SYNOVIAL MEMBRANES 265
by Clopton Havers as mucilaginous glands, and as the source of the synovial secre-
tion. Under certain diseased conditions similar processes are found covering
the entire surface of the synovial membrane, forming a mass of pedunculated
fibro-fatty growths which project into the joint. Similar structures are also
found in some of the bursal and vaginal synovial membranes.
Bursal Synovial Membrane. — The bursal synovial membranes are sacs inter-
posed between surfaces which move upon each other, producing friction, as in the
gliding of a tendon or of the integument over projecting bony surfaces. There are
two groups of synovial bursae designated according to situation: (1) Those
situated between the integument and a prominent process of bone. Such a bursa
is called a subcutaneous synovial bursa (bursa mucosa subcutanea) (Fig. 246). Sub-
cutaneous bursse are found between the integument and the front of the patella,
over the olecranon, the malleoli, and other prominent parts. (2) Those situated
between tendons or muscles and the bony or cartilaginous surfaces over which
the tendons or muscles glide (Fig. 194). Such a bursa is called a subtendinous
FIG. 194. — Scheme of a serous bursa. (Poirier and Charpy.)
.synovial bursa (bursa mucosa subtendinea). For example, a bursa is placed be-
tween the Glutei muscles and the surface of the great trochanter. Subtendinous
bursae are found often about joints and not unusually communicate directly
with the cavity of the joint by means of an opening in the joint capsule, the syno-
vial membrane of the joint being continuous with the synovial membrane of the
tursa. For instance, the bursa between the tendon of the Psoas and Iliacus
muscles and the capsular ligament of the hip communicates with the hip-joint;
:and the bursa between the under surface of the Subscapularis muscle and the neck
of the scapula communicates with the shoulder-joint. Bursse consist of a thin wall
of connective tissue, partially covered by patches of cells, and contain a viscid fluid.
Vaginal Synovial Membrane (Figs. 232 and 324). — A vaginal synovial membrane
which is the synovial sheath or the thecal synovial bursa (vagina mucosa tendinis}
serves to facilitate the gliding of a tendon in the osseo-fibrous canal through which
it passes. The membrane is here arranged in the form of a sheath, one layer of
which adheres to the wall of the canal, and the other is reflected upon the surface of
the contained tendon, the space between the two free surfaces of the membrane
containing synovia. These sheaths are chiefly found surrounding the tendons of
the Flexor and Extensor muscles of the fingers and toes as they pass through the
osseo-fibrous canals in the hand or foot. A vaginal sheath covers the long head
of the Biceps muscle from its origin to the surgical neck of the humerus (Fig. 222).
Pads of adipose tissue (synovial fat pads] are found in certain joints between
folds of the synovial membrane or between the synovial membrane and the
surface beneath it. These pads fill up certain joint intervals, and by adapting
themselves to changes of position maintain the form of the joint during movement.
The articulations are divided into three classes: synarthrosis, or immovable;
amphiarthrosis, or mixed; and diarthrosis, or movable joints.
266 THE ARTICULATIONS OR JOINTS
Synarthrosis (Immovable Articulation).
Synarthrosis includes all those articulations in which the surfaces of the bones
are in almost direct contact, being fastened together by an intervening mass of
connective tissue, and in which there is no joint cavity and no appreciable motion.
Examples of Synarthrosis are the joints between the bones of the cranium and
of the face, excepting those of the lower jaw. The varieties of Synarthrosis are
four in number: sutura, schindylesis, gomphosis, and synchondrosis.
Sutura. — Sutura (a seam) is that form of articulation met with only in the
skull, where the contiguous margins of flat bones are apparently but not really
in immediate contact, a thin layer of fibrous tissue, sutural membrane, being
interposed. This membrane is continuous externally with the pericranium and
internally with the dura. In some of the sutures the sutural membrane gradu-
ally disappears as age advances and the two bones form an osseous fusion. Where
the articulating surfaces are connected by a series of processes arid indenta-
tions interlocked together, it is termed a true suture or sutura vera, of which there
are three varieties : sutura dentata, serrata, and limbosa. The sutura dentata (dens,
a tooth) is so called from the tooth-like form of the projecting articular processes,
as in the suture between the parietal bones. In the sutura serrata (serra, a saw)
the edges of the two bones forming the articulation are serrated like the teeth
of a fine saw, as between the two portions of the frontal bone. In the sutura
limbosa (limbus, a selvage), besides the dentated processes, there is a certain
degree of bevelling of the articular surfaces, so that the bones overlap one another,
as in the suture between the parietal and frontal bones. AVhen the articulation
is formed by roughened surfaces placed in apposition with one another, it is
termed the false suture (sutura nothd), of which there are two kinds: the sutura
squamosa (squama, a scale), formed by the overlapping of two contiguous bones
by broad bevelled margins, as in the squamo-parietal (squamous) suture; and
the sutura harmonia (bpfiovta,, a joining together), where there is simple apposition
of two contiguous, rough, bony surfaces, as in the articulation between the two
superior maxillary bones or of the horizontal plates of the palate bones.
Schindylesis. — Schindylesis (a-^cvd(jXYja:<;, a fissure) is that form of articulation
in which a thin plate of bone is received into a cleft or fissure formed by the sep-
aration of two laminae in another bone, as in the articulation of the rostrum of the
sphenoid and perpendicular plate of the ethmoid with the vomer, or in the recep-
tion of the latter in the fissure between the superior maxillary and palate bones.
Gomphosis. — Gomphosis (rbfjupot;, a nail) is an articulation formed by the
insertion of a cofiical process into a socket, as a nail is driven into a board; this
is not illustrated by any articulation between bones, properly so called, but is
seen in the articulation of the teeth with the alveoli of the maxillary bones.
Synchondrosis. — Where the connecting medium is cartilage the joint is termed
a synchondrosis. This is a temporary form of joint, because the hyaline cartilage
becomes converted into bone before adult life. Such a joint is found between
the epiphyses and shafts of long bones. Another example of a synchondrosis is
the occipito-sphenoid articulation.
Amphiarthrosis (Mixed Articulation).
In this form of articulation the contiguous osseous surfaces may be connected
together by broad flattened disks of fibro-cartilage, of a more or less complex
structure, which adhere to the end of each bone, as in the articulation between
the bodies of two vertebrae and that between the pubic bones at the symphysis.
This is termed symphysis. In a symphysis there is a partial joint-cavity which may
exhibit an incomplete synovial membrane. Each constituent bone is coated with
hyaline cartilage and the bones are held together by ligaments and intervening
DIARTHROSIS 267
fibre-cartilage. The bony surfaces of an amphiarthrodial joint may be united
by an interosseous ligament, as in the inferior tibio-fibular articulation. To such
an articulation the term syndesmosis is applied. A mixed articulation permits
limited motion.
Diarthrosis (Movable Articulation).
This form of articulation includes the greater number of the joints in the body,
mobility being their distinguishing character. They are formed by the approxi-
mation of two contiguous bony surfaces covered with cartilage, connected by
ligaments and lined by synovia! membrane. The varieties of joints in this class
have been determined by the kind of motion permitted in each. There are two
varieties in which the movement is uniaxial; that is to say, all movements take
place around one axis. In one form, the ginglymus or hinge-joint, this axis is,
practically speaking, transverse; in the other, the trochoid or pivot-joint, it is
longitudinal. There are two varieties where the movement is biaxial or around
two horizontal axes at right angles to each other or at any intervening axis
between the two. These are the condyloid -joint and the saddle -joint. There is
one form of joint where the movement is polyaxial, the enarthrosis or ball-and-
socket joint. And finally there are the arthrodia or gliding joints. In a diarthrosis
there is always a joint cavity lined with synovial membrane — the articular sur-
faces of the bones are covered with hyaline cartilage and the bones are held in
contact by ligaments.
Ginglymus or Hinge- joint (jifftopo?, a hinge). — In this form of joint the
articular surfaces are moulded to each other in such a manner as to permit motion
only in one plane, forward and backward ; the extent of motion at the same time
being considerable. The direction which the distal bone takes in this motion is
never in the same plane as that of the axis of the proximal bone, and there is
always a certain amount of alteration from the straight line during flexion. The
articular surfaces are connected together by strong lateral ligaments, which form
their chief bond of union. The most perfect forms of ginglymus are the inter-
phalangeal joints and the joint between the humerus and ulna; the knee and
ankle are less perfect, as they allow a slight degree of rotation or lateral move-
ment in certain positions of the limb.
Trochoid or Pivot-joint or Rotary-joint. — Where the movement is limited to
rotation, the joint is formed by a pivot-like process turning within a ring, or the
ring on the pivot, the ring being formed partly of bone, partly of ligament. In
the superior radio-ulnar articulation the ring is formed partly by the lesser sig-
moid cavity of the ulna; in the rest of its extent, by the orbicular ligament; here
the head of the radius rotates within the ring. In the articulation of the odontoid
process of the axis with the atlas the ring is formed in front by the anterior arch
of the atlas; behind, by the transverse ligament; here the ring rotates round 'the
odontoid process.
Condyloid or Biaxial Articulation. — In this form of joint an ovoid articular
head, or condyle, is received into an elliptical cavity in such a manner as to per-
mit of flexion and extension, adduction and abduction and circumduction, but
no axial rotation. The articular surfaces are connected together by anterior,
posterior, and lateral ligaments. An example of this form of. joint is found in
the wrist.
Articulation by Reciprocal Reception or Saddle-joint. — In this variety the
articular surfaces are concavo-convex; that is to say, they are inversely convex in
one direction and concave in the other. The movements are the same as in the
preceding form; that is to say, there is flexion, extension, adduction, abduction,
and circumduction, but no axial rotation. The articular surfaces are connected
268
THE ARTICULATIONS OR JOINTS
by a capsular ligament. The best example of this form of joint is the carpo-
metacarpal joint of the thumb.
Enarthrosis, or Ball-and-socket-joint, is that form of joint in which the distal
bone is capable of motion around an indefinite number of axes which have one
common centre. It is formed by the reception of a globular head into a deep
cup-like cavity (hence the name "ball-and-socket"), the parts being kept in
apposition by a capsular ligament strengthened by accessory ligamentous bands.
Examples of this form of articulation are found in the hip and shoulder.
Arthrodia. — Arthrodia is that form of joint which admits of a gliding move-
ment; it is formed by the approximation of plane surfaces or of one slightly con-
cave to one slightly convex, the amount of motion between them being limited
by the ligaments, or osseous processes, surrounding the articulation; as in the
articular processes of the vertebrae, the carpal jointr, except that of the os magnum
with the scaphoid and semilunar bones, and the tarsal joints with the exception
of the joint between the astragalus and the scaphoid.
Below, in tabular form, are the names, distinctive characters, and examples
of the different kinds of articulations.
The Kinds of Movement Admitted in Joints.
The movements admissible in joints may be divided into four kinds: gliding,
angular movement, circumduction, and rotation. These movements are often,
however, more or less combined in the various joints, so as to produce an infinite
variety, and it is seldom that we find only one kind of motion in any particular joint.
Dentata, having
tooth-like processes.
As in interparietal
suture.
Serrata, having ser-
rated edges like the
teeth of a saw.
As in interfrontal
suture.
Limbosa, having
Sutura. A.r- bevelled margins and
ticulation by dentated processes,
processes and As in fronto-parie-
indentations 1 l^tal suture,
interlocked f Squamosa, formed
together. by thin bevelled mar-
gins, overlapping each
other.
As in squamo-parie-
tal suture.
Harmonia, formed by
the apposition of con-
tiguous rough surfaces.
As in intermaxillary
suture.
Schindylesis. — Articulation formed by the reception of a
thin plate of one bone into a fissure of another.
As in articulation of rostrum of sphenoid with vomer.
Gomphosis. — Articulation formed by the insertion of a
conical process into a socket: the teeth.
Synarthrosis, or
Immovable Joint.
Surfaces separated
by fibrous mem-
brane or by line
of cartilage, with-
out any interven-
ing synovial
cavity, and im-
movably con-
nected with each
other. •
As in joints of
cranium and face
(except lower
jaw).
Sutura vera
(true), articulate
by indented bor-
ders.
Sutura notha
(false) „ articulate
.by rough surfaces.
THE KINDS OF MOVEMENT ADMITTED IN JOINTS 269
Amphiarthrosis, \
Mixed Articula--j
tion.
Diarthrosis,
Movable Joint.
Symphysis. — Surfaces connected by fibro-cartilage. There
is a Partial Joint ca?'lty and mav be an incomplete synovia!
membrane. Has limited motion. As in joints between
bodies of vertebrae.
Syndesmosis. — Surfaces united by an interosseous liga-
Lment. As in the inferior tibio-fibular articulation.
Ginglymus. — Hinge-joint; motion limited to two directions,
forwaid and backward. Articular surfaces fitted together
so as to permit of movement in one plane. As in the inter-
phalangeal joints and the joint between the humerus and the
ulna.
Trochoides, or Pivot-joint. — Articulation by a pivot process
turning within a ring or ring around a pivot. As in superior
radio-ulnar articulation and atlanto-axial joint.
Condyloid. — Ovoid head received into elliptical cavity.
Movements in every direction except axial rotation. As the
wrist-joint.
Reciprocal Reception (saddle-joint). — Articular surfaces
inversely convex in one direction and concave in the other.
Movement in every direction except axial rotation. As in
the carpo-metacarpal joint of the thumb.
Enarthrosis. — Ball-and-socket joint; capable of motion in
all directions. Articulations by a globular head received
into a cup-like cavity. As in hip- and shoulder-joints.
Arthrodia. — Gliding joint; articulations by plane surfaces,
which glide upon each other. As in carpal and tarsal articu-
^ lations.
Gliding movement is the most simple kind of motion that can take place in a
joint, one surface gliding or moving over another without any angular or rotatory
movement. It is common to all movable joints, but in some, as in the articu-
lations of the carpus and tarsus, it is the only motion permitted. This movement
is not confined to plane surfaces, but may exist between any two contiguous
surfaces, of whatever form, limited by the ligaments which enclose the articu-
lation. Gliding over a wide range, as is seen in the sliding of the patella over
the femur, is called coaptation.
Angular movement occurs only between the long bones, and by it the angle
between the two bones is increased or diminished. It may take place in four
directions: forward and backward, constituting flexion or bending and extension
or straightening, or inward toward and outward from the medial line of the body,
constituting adduction and abduction. Abduction of a limb is movement away
from the medial line of the body. Adduction of a limb is movement toward the
medial line of the body. In the fingers and toes the significance of the terms are
different; abduction means movement of the fingers away from the middle finger
or of the toe away from the second toe; adduction means movement of fingers
toward the middle finger or of the toes toward the second toe. The strictly gingly-
moid or hinge-joints admit of flexion and extension only. Abduction and adduc-
tion, combined with flexion and extension, are met with in the more movable
joints; as in the hip-, shoulder-, and metacarpal-joint of the thumb, and partially
in the wrist. When two anterior surfaces are brought nearer together, as by
bending the elbow or wris£, we speak of the movement as ventral or anterior
flexion. Ventral flexion of the wrist is also called volar or palmar flexion. If
two posterior surfaces are brought nearer together, as by bending the knee or
extending the wrist, we speak of the movement as posterior or dorsal flexion.
270 THE ARTICULATIONS OR JOINTS
At the wrist-joint the bending of the ulnar margin of the hand toward the
ulnar side of the forearm is ulnar flexion; the bending of the radial margin of
the hand toward the radial side of the forearm is radial flexion.
Circumduction is that limited degree of motion which takes place between the
head of the bone and its articular cavity, whilst the extremity and sides of the limb
are made to circumscribe a conical space, the base of which corresponds with the
inferior extremity of the limb, the apex with the articular cavity; this kind of
motion is best seen in the shoulder- and hip-joints.
Rotation is the movement of a bone upon an axis, which is the axis of the pivot
on which the bone turns, as in the articulation between the atlas and axis, when
the odontoid process serves as a pivot around which the atlas turns; or else is the
axis of a pivot-like process which turns within a ring, as in the rotation of the
radius upon the humerus.
Ligamentous Action of Muscles. — The movements of the different joints of
a limb are combined by means of the long muscles which pass over more than one
joint, and which, when relaxed and stretched to, their greatest extent, act as
elastic ligaments in restraining certain movements of one joint, except when
combined with corresponding movements of the other, these latter movements
being usually in the opposite direction. Thus the shortness of the hamstring
muscles prevents complete flexion of the hip, unless the knee-joint is also flexed,
so as to bring their attachments nearer together. The uses of this arrangement
are threefold: 1. It co-ordinates the kinds of movement which are the most
habitual and necessary, and enables them to be performed with the least expendi-
ture of power. "Thus in the usual gesture of the arms, whether in grasping or
rejecting, the shoulder and the elbow are flexed simultaneously, and simultane-
ously extended," in consequence of the passage of the Biceps and Triceps cubiti
over both joints. 2. It enables the short muscles which pass over only one joint
to act upon more than one. "Thus, if the Rectus femoris remain tonically of
such length that, when stretched over the extended hip, it compels extension of
the knee, then the Glutens maximus becomes not only an extensor of the hip, but
an extensor of the knee as well." 3. It provides the joints with ligaments which,
while they are of very great power in resisting movements to an extent incom-
patible with the mechanism of the joint, at the same time spontaneously yield
when necessary. "Taxed beyond its strength, a ligament will be ruptured,
whereas a contracted muscle is easily relaxed; also, if neighboring joints be
united by ligaments, the amount of flexion or extension of each must remain in
constant proportion to that of the other; while, if the union be by muscles, the
separation of the points of attachment of those muscles may vary considerably
in different varieties of movement, the muscles adapting themselves tonically
to the length required." The quotations are from a very interesting paper by
Dr. Cleland iij the Journal of Anatomy and Physiologij, No. 1, 1866, p. 85; by
whom I believe this important fact in the mechanism of joints was first clearly
pointed out, though it has been independently observed afterward by other
anatomists. Dr. W. W. Keen points out how important it is "that the surgeon
should remember this ligamentous action of muscles in making passive motion—
for instance, at the wrist after Colles's fracture. If the fingers be extended, the
wrist can be flexed to a right angle. If, however, they be first flexed, as in
'making a fist/ flexion at the wrist is strictly limited to from 40 to 50 degrees in
different persons, and is very painful beyond that point. Hence passive motion
here should be made with the fingers extended. In the leg, when flexing the hip,
the knee should be flexed." Dr. Keen further points out that "a beautiful illus-
tration of this is seen in the perching of birds, whose toes are forced to clasp the
perch by just such a passive ligamentous action so soon as they stoop. Hence
they can go to sleep and not fall off the perch."
ARTICULATIONS OF THE VERTEBRAL COLUMN 271
The articulations may be arranged into those of the trunk, those of the upper
extremity, and those of the lower extremity.
ARTICULATIONS OF THE TRUNK.
These may be divided into the following groups, viz. :
I. Of the vertebral column.
II. Of the atlas with the axis.
III. Of the atlas with the occipital
bone.
IV. Of the axis with the occipital bone.
V. Of the lower jaw.
VI. Of the ribs with the vertebrae.
VII. Of the cartilages of the ribs with
the sternum and with each other.
VIII. Of the sternum.
IX. Of the vertebral column with the
pelvis.
X. Of the pelvis.
I. Articulations of the Vertebral Column.
The different segments of the spine are connected together by spinal ligaments
(ligamenta columnar vertebralis) , which may be divided into five sets: 1. Those
connecting the bodies of the vertebrae. 2. Those connecting the laminae.
3. Those connecting the articular processes. 4. Those connecting the spinous
processes. 5. Those of the transverse processes.
The articulations of the bodies of the vertebrae with each other form a series of
amphiarthrodial joints; those between the articular processes form a series of
arthrodial joints.
1. THE LIGAMENTS OF THE VERTEBRAL BODIES OR CENTRA (!NTERCENTRAL
LIGAMENTS).
Anterior Common Ligament (anterior longitudinal ligament).
Posterior Common Ligament (posterior longitudinal ligament).
Intervertebral Substance (intervertebral disk, fibro-cartilage).
The Anterior Common or Anterior Longitudinal Ligament (ligamentum longitu-
dinale anterius) (Figs. 197, 199, and 203) is a broad and strong band of longi-
tudinal fibres which extends along the anterior (ventral) surface of the bodies of
the vertebrae from the axis to the sacrum. It is broader below than above, thicker
in the thoracic than in the cervical or lumbar regions, and somewhat thicker
opposite the front of the body of each vertebra than opposite the intervertebral
substance. It is attached, above, to the body of the axis by a pointed process,
where it is continuous with the anterior atlanto-axial ligament, is connected
with the tendon of insertion of the Longus colli muscle, and extends down as far
as the upper bone of the sacrum. It consists of dense longitudinal fibres, which
are intimately adherent to the intervertebral substance and the prominent margins
of the vertebrae, but less closely to the middle of the bodies. In the latter
situation the fibres are exceedingly thick, and serve to fill up the concavities
on their front surface and to make the anterior surface of the spine more even.
This ligament is composed of several layers of fibres, which vary in length, but
are closely interlaced with each other. The most superficial or longest fibres
extend between four or five vertebrae. A second subjacent set extends between
two or three vertebrae, whilst a third set, the shortest and deepest, extends from
one vertebra to the next. At the side of the bodies the ligament consists of a
few short fibres, which pass from one vertebra to the next, separated from the
median portion by large oval apertures for the passage of vessels.
272
THE ARTICULATIONS OR JOINTS
The Posterior Common or Posterior Longitudinal Ligament (ligamentum longi-
tudinale posterius) (Figs. 195, 197, 202, and 203) is situated within the spinal
canal, and extends along the posterior (dorsal) surface of the bodies of the ver-
tebrae from the body of the axis above, where it is continuous with the posterior
INTERVERTE-
BRAL FIBRO-
CARTILAGE
ROOT OF
VERTEBRAL
ARCH
POSTERIOR COMMON
LIGAMENT
FIG. 195. — Vertebral bodies with ligaments, from
behind. (Spalteholz.)
FIG. 196. — Interyertebral disk, with the adjacent
vertebral bodies, from in front. (Spalteholz.)
occipito-axial ligament, to the sacrum
below. It can be separated from the
posterior occipito-axial ligament, as is
shown in Fig. 203, and maybe regarded
as really arising from the clivus. It is.
broader above than below, and thicker in
the thoracic than in the cervical or lumbar
regions. In the situation of the intervertebral substance and contiguous margins
of the vertebrae, where the ligament is more intimately adherent, it is broad, and
presents a series of dentations with intervening concave margins; but it is narrow
and thick over the centre of the bodies, from which it is separated by the vena?
basis vertebra?. This ligament is composed of smooth, shining, longitudinal
fibres, denser and more compact than those of the anterior ligament, and formed
of a superficial layer occupying the interval between three or four vertebrae, and
of a deeper layer which extends between one vertebra and the next adjacent
to it. It is separated from the dura of the spinal cord by some loose connective
tissue, which is very liable to serous infiltration.
The Intervertebral Fibro-cartilages, Disks, or Substances (fibrocartilagines inter-
vertebrales) (Figs. 196 and 197). — Each fibro-cartilaginous disk is of lenticular
form and of composite structure. The disks are interposed between the adjacent
surfaces of the bodies of the vertebras from the axis to the sacrum, and form
the chief bonds of connection between those bones. In young children inter-
vertebral substance exists in the coccyx. These disks vary in shape, size, and
thickness in different parts of the spine. In shape they accurately correspond
with the surfaces of the bodies between which they are placed, being oval in the
cervical arid lumbar regions, and circular in the thoracic. Their size is greatest
in the lumbar region. In thickness they vary not only in the different regions
of the spine,' but in different parts of the same disk: thus, they are thicker in
front than behind in the cervical and lumbar regions, while they are uniformly
thick in the thoracic region. The intervertebral disks form about one-fourth of
the spinal column, exclusive of the first two vertebrae; they are not equally dis-
tributed, however, between the various bones; the thoracic portion of the spine
ARTICULATIONS OF THE VERTEBRAL COLUMN
273
having, in proportion to its length, a much smaller quantity than in the cervical
and lumbar regions, which necessarily gives to the latter parts greater pliancy
and freedom of movement. The intervertebral disks are adherent, by their sur-
faces, to a thin layer of hyaline cartilage which covers the upper and under sur-
faces of the bodies of the vertebrae, and in which, in early life, the epiphysial
plate develops, and by their circumference are closely connected in front to the
anterior, and behind to the posterior common ligament; whilst in the thoracic
region they are connected laterally, by means of the interarticular ligament, to
the heads of those ribs which articulate with two vertebrae; they, consequently,
form part of the articular cavities in which the heads of these bones are received.
POSTERIOR COMMON
LIGAMENT
FIG. 197. — Median section of a piece of the lumbar spinal column, right half of sections viewed from the
left. (Spalteholz.)
Structure of the Intervertebral Substance. — The outer portion of the intervertebral
substance is composed of many layers of fibrous connective tissue. This envel-
oping portion is called the annulus fibrosus. The central portion of the disk is
composed of soft, pulpy, highly elastic fibre-cartilage, containing some bands of
connective tissue. It is called the nucleus pulposus, is of a yellowish color, and
rises up considerably above the surrounding level when the disk is divided hori-
zontally. This pulpy substance, which is especially well developed in the lumbar
region, is the remains of the chorda dorsalis, and, according to Luschka, contains a
small synovial cavity in its centre. The outer layers of the disk are arranged con-
centrically one within the other, the outermost consisting of ordinary fibrous tissue,
but the others and more numerous consisting of white fibre-cartilage. These
plates are not quite vertical in their direction, those near the circumference being
curved outward and closely approximated; whilst those nearest the centre curve
in the opposite direction, and are somewhat more widely separated. The fibres of
which each plate is composed are directed, for the most part, obliquely from above
downward, the fibres of adjacent plates passing in opposite directions and varying
in every layer; so that the fibres of one layer are directed across those of another,
like the limbs of the letter X. This laminar arrangement belongs to about the
outer half of each disk. The pulpy substance presents no concentric arrangement,
and consists of a fine fibrous matrix, containing angular cells, united to form a
18
274
THE ARTICULATIONS OR JOINTS
reticular structure. J. Bland Sutton1 calls attention to the fact that in the human
foetus a transverse ligamentous band crosses the dorsal aspect of the intervertebral
disk and is continuous with the interosseous ligaments of the heads of the ribs;
and also that a foetal ligamentous band exists in the ventral surface of the inter-
vertebral disk which, after development, becomes the middle fasciculus of the
stellate ligament. These bands are named by Sutton the posterior conjugal
ligaments and the anterior conjugal ligaments.
Interneural Articulations include the ligaments of the laminae; articular
processes, spinous processes, and transverse processes.
2. LIGAMENTS CONNECTING THE LAMINAE.
Ligamenta Subflava.
The Ligamenta Subflava (ligamenta flava, ligamenta intercruralia) (Figs. 197
and 198) are interposed between the laminae of the vertebra, from the axis to
the sacrum. They are most distinct when seen from the interior of the spinal
canal; when viewed from the outer surface they appear short, being over-
lapped by the laminae. Each ligamentum subflavum consists of two lateral
portions, which commence on each side at the root of either articular process,
and pass backward to the point where the laminae converge to form the spi-
nous process, where their margins are in contact and to a certain extent united;
slight intervals being left for the passage of small vessels. These ligaments
consist of yellow elastic tissue, the
fibres of which, almost perpendic-
ular in direction, are attached to
the anterior surface of the laminae
above, some distance from its in-
ferior margin, and to the posterior
surface, as well as to the margin
of the lamina below. In the cer-
vical region they are thin in tex-
ture, but very broad and long;
they become thicker in the thoracic
region, and in the lumbar acquire
very considerable thickness. Their
highly elastic property serves to
preserve the upright posture and
to assist in resuming it after the
spine has been flexed. These liga-
ments do not exist between the
occiput and atlas or between the
atlas and axis.
3. LIGAMENTS CONNECTING THE
ARTICULAR PROCESSES.
Capsular Ligaments.
The Capsular Ligaments (capsulae
FIG. 198.— Vertebral arches with ligamenta flava. artlCulares] (FifiT. 199) are thin and
(Spalteholz.) IT u J
loose ligamentous sacs, attached
to the contiguous margins of the articulating processes of each vertebra through
the greater part of their circumference, and completed internally by the ligamenta
1 J. Bland Sutton. Ligaments: Their Nature and Morphology.
ARTICULATIONS Of THE VERTEBRAL COLUMN 275
subflava. They are longer and looser in the cervical than in the thoracic or lumbar
regions. The capsular ligaments are lined on their inner surface by synovial
membrane.
4. LIGAMENTS CONNECTING THE SPINOUS PROCESSES.
Supraspinous Ligament Interspinous Ligaments.
The Supraspinous Ligament (ligamentum supraspinale) (Fig. 197) is a strong
fibrous cord, which connects together the apices of the spinous processes from the
seventh cervical to the spinous processes of the sacrum. It is thicker and broader
in the lumbar than in the thoracic region, and intimately blended, in both situa-
tions, with the neighboring aponeurosis. The most superficial fibres of this
ligament connects three or four vertebrae; those deeper-seated pass between two
or three vertebrae; whilst the deepest connect the contiguous extremities of
neighboring vertebras. It is continued upward to the external occipital protu-
berance as the ligamentum nuchae, which, in the human subject, is thin and forms
merely an intermuscular septum.
The Interspinous Ligaments (ligamenta interspinalia) (Fig. 197), thin and
membranous, are interposed between the spinous processes. Each ligament
extends from the root to the summit of each spinous process and connects together
their adjacent margins. They meet the ligamenta subflava in front and the
Supraspinous ligament behind. They are narrow and elongated in the thoracic
region; broader, quadrilateral in form, and thicker in the lumbar region; and
only slightly developed in the neck.
5. LIGAMENTS CONNECTING THE TRANSVERSE PROCESSES.
In tertrans verse Ligaments.
The Intertxansverse Ligaments (Ligamenta intertransversaria) (Fig. 210) consist
of bundles of fibres interposed between the transverse processes. In the cervical
region they consist of a few irregular, scattered fibres; in the thoracic, they are
rounded cords intimately connected with the deep muscles of the back; in the
lumbar region they are thin and membranous.
Actions. — The movements permitted in the spinal column are, flexion, exten-
sion, lateral movement, circumduction, and rotation.
In flexion (forward flexion), or movement of the spine forward, the anterior
common ligament is relaxed, and the intervertebral substances are compressed
in front, while the posterior common ligament, the ligamenta subflava, and the
inter- and supra-spinous ligaments are stretched, as well as the posterior fibres
of the intervertebral disks. The interspaces between the laminae are widened,
and the inferior articular processes of the vertebrae above glide upward upon
the articular processes of the vertebrae below. Flexion is the most extensive of
all the movements of the spine.
In extension (backward flexion), or movement of the spine backward, an exactly
opposite disposition of the parts takes place. This movement is not extensive,
being limited by the anterior common ligament and by the approximation of the
spinous processes.
Flexion and extension are free in the lower part of the lumbar region between
the third and fourth and fourth and fifth lumbar vertebras; above the third
they are much diminished, and reach their minimum in the middle and upper
part of the back. They increase again in the neck, the capability of motion
backward from the upright position being in this region greater than that of the
motion forward, whereas in the lumbar region the reverse is the case.
In lateral flexion, the sides of the intervertebral disks are compressed, the
extent of motion being limited by the resistance offered by the surrounding liga-
276 THE ARTICULATIONS OR JOINTS
ments and by the approximati6n of the transverse processes. This movement
may take place in any part of the spine, but is most free in the neck and loins.
Circumduction is very limited, and is produced merely by a succession of the
preceding movements.
Rotation is produced by the twisting of the intervertebral substances; this,
although only slight between any two vertebne, produces a considerable extent of
movement when it takes place in the whole length of the spine, the front of the
upper part of the column being turned to one or the other side. This movement
takes place only to a slight extent in the neck, but is freer in the upper part of
the thoracic region, and is altogether absent in the lumbar region.
It is thus seen that the cervical region enjoys the greatest extent of each variety
of movement, flexion and extension, especially being very free. In the thoracic
region the three movements of flexion, extension, and circumduction are per-
mitted only to a slight extent, while rotation is very free in the upper part and
ceases below. In the lumbar region there is free flexion, extension, and lateral
movement, but no rotation.
As Sir George Humphry has pointed out, the movements permitted are mainly
due to the shape and position of the articulating processes. In the loins the infe-
rior articulating processes are turned outward and are embraced by the superior;
this renders rotation in this region of the spine impossible, while there is nothing-
to prevent a sliding upward and downward of the surfaces on each other, so as to
allow of flexion and extension. In the thoracic region, on the other hand, the
articulating processes, by their direction and mutual adaptation, especially at the
upper part of the series, permit of rotation, but prevent extension and flexion,
while in the cervical region the greater obliquity and lateral slant of the articular
processes allow not only flexion and extension, but also rotation.
The principal muscles which produce flexion are the Sterno-mastoid, Rectus
capitis anticus major, and Longus colli; the Scaleni; the abdominal muscles and
the Psoas magnus. Extension is produced by the fourth layer of the muscles
of the back, assisted in the neck by the Splenius, Semispinalis dorsi et colli, and
the Multifidus spinae. Lateral motion is produced by the fourth layer of the
muscles of the back, by the Splenius and the Scaleni, the muscles of one side only
acting; and rotation by the action of the following muscles of one side only — viz.
the Sterno-mastoid, the Rectus capitis anticus major, the Scaleni, the Multifidus
spinse, the Complexus, and the abdominal muscles.
II. Articulation of the Atlas with the Axis (Articulatio Atlantoepistrophica).
The articulation of the atlas with the axis is of a complicated nature, compris-
ing no fewer than four distinct joints. There is a pivot articulation between the
odontoid process of the axis and the ring formed between the anterior arch of the
atlas and the transverse ligament (see Fig. 201). Here there are two joints: one in
front between the posterior surface of the anterior arch of the atlas and the front
of the odontoid process, the atlanto-odontoid joint of Cruveilhier ; the other between
the anterior surface of the transverse ligament and the back of the process, the
syndesmo-odontoid joint. Between the articular processes of the two bones there
is a double arthrodia or gliding joint. The ligaments which connect these bones
are the
Anterior Atlanto-axial. Transverse.
Posterior Atlanto-axial. Two Capsular.
The Anterior Atlanto-axial or the Anterior Atlo-axoid Ligament (Figs. 199 and 203)
is a strong, membranous layer, attached, above, to the lower border of the anterior
arch of the atlas; below, to the base of the odontoid process and to the front of
ARTICULATION OF THE ATLAS WITH THE AXIS
277
the body of the axis. It is strengthened in the middle line by a rounded cord, which
is attached, above, to the tubercle on the anterior arch of the atlas, and below to
the body of the axis, being a continuation upward of the anterior common liga-
ment of the spine. Some anatomists regard this ligament as being a part of the
anterior common ligament. The ligament is in relation, in front, with the Recti
antici majores.
The Posterior Atlanto-axial or the Posterior Atlo-axoid Ligament (Figs. 200 and
203) is a broad and thin membranous layer, attached, above, to the lower border
of the posterior arch of the atlas; below, to the upper edge of the laminse of
the axis. This ligament supplies the place of the ligamenta subflava, and is
in relation, behind, with the Inferior oblique muscles.
The Transverse Ligament of the Atlas1 (ligamentum transversum atlantis] (Figs.
201, 202, and 203) is a thick, strong band, which arches across the ring of the
atlas, and serves to retain the odontoid process in firm connection with its anterior
arch. This ligament is flattened from before backward, broader and thicker in
the middle than at either extremity, and firmly attached on each side to a small
tubercle on the inner surface of the lateral mass of the atlas. As it crosses the
odontoid process, a small fasciculus is derived from its upper, and another from
its lower, border; the former passing upward, to be inserted into the anterior sur-
PHARYNGEAL
TUBERCLE BASILAR PORTION Or
OCCIPITAL BONE
ANTERIOR OCCIPITO-
ATLANTAL LIGAMENT
JOINT BETWEEN
BODY OF VERTEBRA
AND INTERVER-.
TCBRAL FIBRO-
CARTILAGE
ANTERIOR CONDYLOID
FORAMEN
OCCIPITO-ATLANTAL
ARTICULATION
TRANSVERSE
PROCESS OF
ATLAS
ANTERIOR ATLANTO-
AXIAL LIGAMENT
TRANSVERSE
PROCESS OF
AXIS
TRANSVERSE PROCESS
OF THIRD CERVICAL
VERTEBRA
INTCRVERTEBRAL
FIBROCARTI LAGE
ANTERIOR COMMON
LIGAMENT
FIG. 199. — Occipital bone and first three cervical vertebrae with ligaments, from in front. (Spalteholz.)
face of the foramen magnum of the occipital bone; the latter, downward, to be
attached to the posterior surface of the body of the axis; hence, the whole ligament
has received the name of cruciform ligament (ligamentum cruciatum atlantis).
A synovial surface is interposed between the odontoid process and the trans-
verse ligament, and one is placed between the anterior surface of the odontoid
process and the anterior arch of the atlas. The transverse ligament divides the
1 It has been found necessary to describe the transverse ligament with those of the atlas and axis; but the
student must remember that it is really a portion of the mechanism by which the movements of the head on
the spine are regulated; so that the connections between the atlas and axis ought always to be studied
together with those between the latter bones and the skull. — ED. of 15th English Edition.
278 THE ARTICULATIONS OR JOINTS
ring of the atlas into two unequal parts : of these, the posterior and larger serves
for the transmission of the cord and its membranes and the accessory nerves ; the
anterior and smaller contains the odontoid process. Since the space between
the anterior arch of the atlas and the transverse ligament is smaller at the lower
part than the upper (because the transverse ligament embraces tightly the narrow
neck of the odontoid process), this process is retained in firm connection with the
atlas after all the other ligaments have been divided.
The Capsular Ligaments (capsidae articulares) (Figs. 199, 200, and 202) are two-
thin an.d loose capsules, connecting the lateral masses of the atlas with the superior
articular surfaces of the axis, the fibres being strengthened at the posterior and
inner part of each articulation by an accessory ligament, which is attached below
to the body of the axis near the base of the odontoid process.
Synovial Membranes (Fig. 201). — There are four synovial membranes in this
articulation: one lining the inner surface of each of the capsular ligaments; one
between the anterior surface of the odontoid process and the anterior arch of
the atlas, the atlanto-odontoid joint; and one between the posterior surface of
the odontoid process and the transverse ligament, the syndesmo-odontoid joint.
The latter often communicates with those between the condyles of the occipital
bone and the articular surfaces of the atlas.
Actions. — This joint allows the rotation of the atlas (and, with it, of the cra-
nium) upon the axis, the extent of rotation being limited by the odontoid ligaments.
The principal muscles by which this action is produced are the Sterno-mastoid
and Complexus of one side, acting with the Rectus capitis anticus major, Sple-
nius, Trachelo-mastoid, Rectus capitis posticus major, and Inferior oblique of the
other side.
ARTICULATIONS OF THE SPINE WITH THE CRANIUM.
The ligaments connecting the spine with the cranium may be divided into two
sets — those connecting the occipital bone with the atlas, and those connecting the
occipital bone with the axis.
III. Articulation of the Atlas with the Occipital Bone (Articulatio
Atlantooccipitalis) .
This articulation is a double condyloid joint. Its ligaments are the
Anterior Occipito-atlantal. Posterior Occipito-atlantal.
Two Capsular.
The Anterior Occipito-atlantal Ligament or Membrane (membrana atlantooccipitalis
anterior, anterior occipito-atloid ligament) (Figs. 199 and 203) is a broad membra-
nous layer, composed of densely woven fibres, which passes between the anterior
margin of the foramen magnum above, and the whole length of the upper border
of the anterior arch of the atlas below. Laterally, it is continuous with the cap-
sular ligaments. In the middle line in front it is strengthened by a strong, narrow,
rounded cord, which is attached, above, to the basilar process of the occiput, and,
below, to the tubercle on the anterior arch of the atlas, and which is a continua-
tion of the anterior common ligament. This ligament is in relation, in front,
with the Recti antici minores ; behind, with the odontoid ligaments.
The Posterior Occipito-atlantal Ligament or Membrane (membrana atlantooccipitalis
posterior, posterior occipito-atloid ligament) (Figs. 200 and 203) is a very broad but
thin membranous lamina intimately blended with the dura. It is connected,
above, to the posterior margin of the foramen magnum; below, to the upper border
ARTICULATION OF THE ATLAS WITH THE OCCIPITAL BONE 279
of the posterior arch of the atlas. This ligament is incomplete at each side, and
forms, with the superior intervertebral notch, an opening for the passage of the
vertebral artery and suboccipital nerve. The fibrous band which arches over the
artery and nerve sometimes becomes ossified. The ligaments are in relation,
behind, with the Recti postici minores and Obliqui superiores; in front, with the
dura of the spinal canal, to which they are intimately adherent.
POSTERIOR OC-
CIPITO-ATLAIMTAL
LIGAMENT
POSTERIOR OC-
CIPITO-ATLANTAL
LIGAMENT
POSTERIOR
ATLANTO-AXIAL'
LIGAMENT
TRANSVERSE
PROCESS OF
ATLAS
TRANSVERSE
PROCESS OF
AXIS
FIG. 200. — Occipital bone, first and second cervical vertebrae with ligaments from behind. (Spalteholz.)
The Capsular Ligaments (capsules articulares) (Fig. 202) surround the condyles
of the occipital bone, and connect them with the articular processes of the atlas;
they consist of thin and loose capsules, which enclose the synovial membranes
of the articulations.
Synovial Membranes. — There are two synovial membranes in this articulation,
one lining the inner surface of each of the capsular ligaments. These occasionally
communicate with that between the posterior surface of the odontoid process and
the transverse ligament.
FIG. 201. — Articulation between odontoid process and atlas.
Actions. — The movements permitted in this joint are flexion and extension,
which give rise to the ordinary forward and backward nodding of the head. Slight
lateral motion to one or the other side may also take place. When either of these
actions is carried beyond a slight extent, the whole of the cervical portion of the spine
assists in its production. Flexion is mainly produced by the action of the Rectus
capitis anticus major et minor and the Sterno-mastoid muscles; extension by the
280
THE ARTICULATIONS OR JOINTS
Rectus capitis posticus major et minor, the Superior oblique, the Complexus, Sple-
nius, and upper fibres of the Trapezius. The Recti laterales are concerned in the
lateral movement, assisted by the Trapezius, Splenius, Complexus, and the Sterno-
mastoid of the same side, all acting together. According to Cruveilhier, there is
a slight motion of rotation in this joint.
IV. Articulation of the Axis with the Occipital Bone.
The ligaments of this articulation are the
Occipito-axial. Three Odontoid.
To expose these ligaments the spinal canal should be laid open by removing
the posterior arch of the atlas, the laminae and spinal process of the axis, and the
portion of the occipital bone behind the foramen magnum, as seen in Fig. 193.
The Posterior Occipito-axial Ligament (posterior occipito-axoid ligament, membrana
tectoria, apparatus ligamentosus colli) (Figs. 202 and 203) is situated within the spinal
canal. It is a broad, strong band, which covers the odontoid process and its liga-
ments, and appears to be a prolongation upward of or a membrane due to fusion
with the posterior common ligament of the spine. It is attached, below, to the
posterior surface of the body of the axis, and, becoming expanded as it ascends,
is inserted into the basilar groove of the occipital bone, in front of the foramen
magnum, where it becomes blended with the dura of the skull.
The vertical portion of
ODONTOID LIGAMENTS.
(CAPSULAR LIGAMENT
1 < and synovial
(_ membrane.
fCAPSULAH LIGAMENT
< and synovial
(_ membrane.
FIG. 202. — Occipito-axial and atlanto-axial ligaments. Posterior view, obtained by removing the arches of
the vertebrae and the posterior part of the skull.
t
Relations. — By its anterior surface with the transverse ligament; by its posterior
surface with the posterior common ligament.
The Lateral Odontoid or Check Ligaments (ligamenta alaria] (Figs. 202 and 203)
are strong, rounded, fibrous cords, which arise one on either side of the upper
part of the odontoid process, and, passing obliquely upward and outward, are
inserted into the rough depressions on the inner side of the condyles of the
ARTICULATION OF THE AXIS WITH THE OCCIPITAL BONE 281
occipital bone. In the triangular interval left between these ligaments another
strong fibrous cord, ligamentum suspensorium, or middle odontoid ligament (liga-
mentum apicis dentis), may be seen, which passes almost perpendicularly from
the apex of the odontoid process to the anterior margin of the foramen mag-
num, being intimately blended with the deep portion of the anterior occipito-
atlantal ligament and upper fasciculus of the transverse ligament of the atlas.
Actions. — The odontoid ligaments serve to limit the extent to which rotation
of the cranium may be carried; hence, they have received the name of check
ligaments.
In addition to these ligaments, which connect the atlas and axis to the skull,
the ligamentum nuchae must be regarded as one of the ligaments by which the
spine is connected with the cranium. It is described on page 275.
Surgical Anatomy. — The ligaments which unite the component parts of the vertebrae
together are so strong, and these bones are so interlocked by the arrangement of their articu-
lating processes, that dislocation is very uncommon, and, indeed, unless accompanied by fracture,
seldom occurs, except in the upper part of the neck. Dislocation of the occiput from the atlas
THIN LAYER OF POSTERIOR COMMON
LIGAMENT SEPARATED FROM THE
POSTERIOR OCCIPITO-AXIAL LIGAMENT
HYPOGLOSSAL
NERVE
ANTERIOR OCCIPITO--1
ATLOID LIGAMENT
POSTERIOR OCCIPITO-
AXIAL LIGAMENT
CRUCIFORM
LIGAMENT
MIDDLE ODONTOID
LIGAMENT
ANTERIOR ARCH
OF ATLAS
ODONTOID PROC-
ESS OF AXIS
ARTICULAR
CAVITY
TRANSVERSE LIGA-
MENT OF ATLAS
ANTERIOR ATLO-
AXOID LIGAMENT
POSTERIOR OCCIP-
ITO- ATLANTAL
LIGAMENT
•POSTERIOR
ARCH OF
ATLAS
SUBOCCI PITAL
NERVE
JNTERVERTE-
BRAL FORAMEN
1NTERVERTEBRAL
FIBRO-CARTILAGE
ANTERIOR COMMON
LIGAMENT
POSTERIOR COMMON
LIGAMENT
FIG. 203. — Median section through the occipital bone and first three cervical vertebrae with ligaments.
(Spalteholz.)
has only been recorded in one or two .cases; but dislocation of the atlas from the axis, with rup-
ture of the transverse ligament, is much more common : it is the mode in which death is produced
in many cases of execution by hanging. Occipito-atloid dislocation is certainly fatal. Recoveries
are on record after atlo-axoid dislocation. Immediate death occurs if the transverse ligament
is torn or the odontoid process is broken. In the lower part of the neck — that is, below the
third cervical vertebra — dislocation unattended by fracture occasionally takes place.
282
THE ARTICULATIONS OR JOINTS
V. Articulation of the Lower Jaw, or the Temporo-mandibular Articulation
(Articulatio Mandibularis).
This is a ginglymo-arthrodial joint: the parts entering into its formation on
each side are, above, the anterior part of the glenoid cavity of the temporal bone
and the eminentia articularis; and, below, the condyle of the lower jaw. The
ligaments are the following:
External Lateral. Stylo-mandibular.
Internal Lateral. Capsular.
Interarticular Fibro-cartilage.
The External Lateral Ligament (ligamentum temporomandibulare} (Fig. 204) is a,
short, thin, and narrow fasciculus, attached, above, to the outer surface of the zygoma
and to the tubercle on its lower border; below, to the outer surface and posterior
border of the neck of the lower jaw. It is broader above than below; its fibres are
FIG. 204. — Temporo-mandibular articulation.
placed parallel with one another, and directed obliquely downward and backward.
Externally, it is covered by the parotid gland and by the integument. Internally
it is in relation with the capsular ligament, of which it is an accessory band, and
from which it is not separable.
The Internal Lateral Ligament (ligamentum sphenomandibulare] (Fig. 205) is a
flat, thin band which is attached above to the spinous process of the sphenoid
bone, and, becoming broader as it descends, is inserted into the margin of the
mandibular or dental foramen and the portion of bone, the lingula, which over-
hangs the foramen in front. Its outer surface is in relation, above, with the
External pterygoid muscle; lower down it is separated from the neck of the
condyle by the internal maxillary artery; and still more inferiorly, the inferior
dental vessels and nerve separate it from the ramus of the jaw. The inner surface
is in relation with the Internal pterygoid. It is really the fibrous covering of a
part of Meckel's cartilage.
ARTICULATION OF THE LOWER JAW
283
-•^•^^'••gyte f • •?'•".•>-••.--•'•-*•'*>•'-•*•• ~-v&
FIG. 205. — Temporo-mandibular articulation. Internal view
The Stylo-mandibular or Stylo -maxillary Ligament (ligamentum stylomandibulare)
(Fig. 205) is a specialized band of the cervical fascia, which extends from near the
apex of the styloid process of the temporal bone to the angle and posterior border
of the ramus of the lower jaw, between the Masseter and Internal pterygoid mus-
cles. This ligament separates the parotid from the submaxillary gland, and has
attached to its inner side part of
the fibres of origin of the Stylo-
glossus muscle. Although usually
classed among the ligaments of the
jaw, it can be considered only as
an accessory to the articulation.
The Capsular Ligament (capsula
articular is) (Figs. 204 and 205)
forms a thin and loose capsule,
passing from the circumference of
the glenoid cavity and the articular
surface immediately in front to the
upper margin of the articular disk,
and from the lower margin of the
articular disk to the neck of the
coridyle of the lower jaw. It con-
sists of very thin fibres, and is com-
plete. It forms two joint cavities,
distinct from each other, and sepa-
rated by the articular disk. So
thin is it that it is hardly to be
considered as a distinct ligament; it is thickest at the back part, and thinnest
on the inner side of the articulation.1
The Interarticular Fibro-cartilage or Meniscus (discus articularis) (Fig. 206) is a
thin plate of an oval form, placed horizontally between the condyle of the jaw and
the glenoid cavity. Its upper surface
is concavo-convex from before back-
ward, and a little convex transversely,
to accommodate itself to the form of
the glenoid cavity. Its under surface,
where it is in contact with the con-
dyle, is concave. Its circumference is
connected to the capsular ligament,
and in front to the tendon of the Ex-
ternal pterygoid muscle. It is thicker
at its circumference, especially be-
hind, than at its centre. The fibres
of which it is composed have a con-
centric arrangement, more apparent
at the circumference than at the
centre. Its surfaces are smooth. It divides the joint into two cavities, each
of which is furnished with a separate synovial membrane from the capsular
ligament.
Synovial Membranes (Fig. 206). — The synovial membranes, two in number, are
placed, one above, and the other below, the fibro-cartilage. The upper one, the
larger and looser of the two, is continued from the margin of the cartilage covering
FIG. 206.— Vertical section of temporo-mandibuiar
i Sir G. Humphry describes the internal portion of the capsular ligament separately as the short internal
lateral ligament: and it certainly seems as deserving of a separate description as is the external lateral liga-
ment.— ED. of 15th English Edition.
284 THE ARTICULATIONS OR JOINTS
the glenoid cavity and eminentia articularis on to the upper surface of the fibro-
cartilage. The lower one passes from the under surface of the fibre-cartilage to
the neck of the condyle of the jaw, being prolonged downward a little farther
behind than in front. The interarticular cartilage is sometimes perforated in its
centre; the two sy no vial sacs then communicate with each other.
The nerves of this joint are derived from the auriculo-temporal and masseteric
branches of the inferior maxillary. The arteries are derived from the temporal
branch of the external carotid.
Actions. — The movements possible in this articulation are very extensive. Thus,
the jaw may be depressed or elevated, or it may be carried forward or backward.
It must be borne in mind that there are two distinct joints in this articula-
tion— that is to say, one between the condyle of the jaw and the interarticular
fibre-cartilage, and another between the fibro-cartilage and the glenoid fossa;
when the jaw is depressed, as in opening the mouth, the movements which take
place in these two joints are not the same. In the lower compartment, that between
the condyle and the fibro-cartilage, the movement is of a ginglymoid or hinge-like
character, the condyle rotating on a transverse axis on the fibro-cartilage; while in
the upper compartment the movement is of a gliding character, the fibro-cartilage,
together with the condyle, gliding forward on to the eminentia articularis. These
two movements take place simultaneously — the condyle and fibro-cartilage move
forward on the eminence, and at the same time the condyle revolves on the fibro-
cartilage. In the opposite movement of shutting the mouth the reverse action takes
place ; the fibro-cartilage glides back, carrying the condyle with it, and this at the
same time revolves back to its former position. When the jaw is carried horizon-
tally forward, as in protruding the lower incisors in front of the upper, the move-
ment takes place principally in the upper compartment of the joint: the fibro-
cartilage, carrying with it the condyle, glides forward on the glenoid fossa. This
is because this movement is mainly effected by the External pterygoid muscles,
which are inserted into both condyle and interarticular fibro-cartilage. The grind-
ing or chewing movement is produced by the alternate movement of one condyle,
with its fibro-cartilage, forward and backward, while the other condyle moves
simultaneously in the opposite direction; at the same time the condyle undergoes a
vertical rotation on its own axis on the fibro-cartilage in the lower compartment.
One condyle advances and rotates, the other condyle recedes and rotates, in alter-
nate succession.
The lower jaw is depressed by its own weight, assisted by the Platysma, the
Digastric, the Mylo-hyoid, and the Genio-hyoid muscles. It is elevated by the
anterior part of the Temporal, Masseter, and Internal pterygoid. It is drawn for-
ward by the simultaneous action of the External pterygoid and the superficial fibres
of the Masseter; and it is drawn backward by the deep fibres of the Masseter and
the posterior fibres of the Temporal muscle. The grinding movement is caused by
the alternate action of the two External pterygoids.
Surface Form. — The temporo-mandibular articulation is quite superficial, situated below the
base of the zygoma, in front of the tragus and external auditory meatus, and behind the poste-
rior border of the upper part of the Masseter muscle. Its exact position can be at once ascer-
tained by feeling for the condyle of the jaw, the working of which can be distinctly felt in the
movements of the lower jaw in opening and shutting the mouth. When the mouth is opened
wide, the condyle advances out of the glenoid fossa on to the eminentia articularis, and a depres-
sion is felt in the situation of the joint.
^ Surgical Anatomy. — Genuine dislocation of the lower jaw is almost always forward. Croker
King and Theim, however, have reported posterior displacement. Dislocation is caused by
violence or muscular action. When the mouth is open, the condyle is situated on the eminentia
articularis, and any sudden violence, or even a sudden muscular spasm, as during a convulsive
yawn, may displace the condyle forward into the zygomatic fossa. The displacement may be
unilateral or bilateral, according as one or both of the condyles is displaced. The latter of
ARTICULATIONS OF THE RIBS WITH THE VERTEBRAE 285
the two is the more common. The interarticular fibro-cartilage adheres to the condyle till it
passes over the eminentia articularis, but at this point remains behind.
Sir Astley Cooper described a condition which he termed " subluxation." It occurs princi-
pally in delicate women, and is believed by some to be due to the relaxation of the ligaments,
permitting too free movement of the bone. Others believe it is due to displacement of the inter-
articular fibro-cartilage. Still others attribute the symptoms to gouty or rheumatic changes in
the joint. In close relation to the condyle of the jaw is the external auditory meatus and the
tympanum; any force, therefore, applied to the bone is liable to be attended with damage to
these parts, or inflammation in the joint may extend to the ear, or on the other hand inflam-
mation of the middle ear may involve the articulation and cause its destruction, thus leading
to ankylosis of the joint. In children, arthritis of this joint may follow the exanthemata, and
in adults it occurs as the result of some constitutional conditions, as rheumatism or gout. The
temporo-mandibular joint is also occasionally the seat of osteo-arthrilis, leading to great suffer-
ing during efforts of mastication. A peculiar affection sometimes attacks the neck and condyle
of the lower jaw, consisting in hypertrophy and elongation of these parts and consequent protru-
sion of the chin to the opposite side.
VI. Articulations of the Ribs with the Vertebrae or the Costo-vertebral
Articulations (Articulationes Costovertebrales).
The articulations of the ribs with the vertebral column may be divided into
two sets: 1. Those which connect the heads of the ribs with the bodies of the
vertebrae; costo-central. 2. Those which connect the necks and tubercles of the
ribs with the transverse processes; costo-trans verse.
1. ARTICULATIONS BETWEEN THE HEADS OF THE RIBS AND THE BODIES OF
THE VERTEBRAE OR THE COSTO-CENTRAL ARTICULATIONS (ARTICU-
LATIONES CAPITULORUM) (Figs. 207 and 208).
These constitute a series of arthrodial joints, formed by the articulation of the
heads of the ribs with the cavities on the contiguous margins of the bodies of the
FOVCA COSTALIS
TRANSVERSALIS
INTERVERTEBRAL
FIBROCARTILAGE
Fio. 207. — Spinal column with ligament, from in front. (Spalteholz.)
286
THE ARTICULATIONS OR JOINTS
INTERARTICULAR LIGA-
MENT OF HEAD OF RIB
thoracic vertebra and the intervertebral substance between them, except in the case
of the first, tenth, eleventh, and twelfth ribs, where the cavity is formed by a single
vertebra. The bones are connected by the following ligaments:
Anterior Costo-vertebral or Stellate.
Capsular. Interarticular.
The Anterior Costo-vertebral or Stellate Ligament (ligamentum capituli costce radi-
atum) (Figs. 207 and 210) connects the anterior part of the head of each rib with the
sides of the bodies of two vertebrae and the intervertebral disk between them. It.
consists of three flat bundles of ligamentous fibres, which are attached to the ante-
rior part of the head of the rib, just beyond the articular surface. The superior
fibres pass upward to be con-
nected with the body of the
vertebra above; the inferior
one descends to the body of
the vertebra below; and the
middle one, the smallest and
least distinct, passes horizon-
tally inward, to be attached
to the intervertebral sub-
stance.
Relations. — In front, with
the thoracic ganglia of the
sympathetic, the pleura, and,
on the right side, with the vena
azygos major; behind, with
the interarticular ligament
and synovial membranes.
On the first rib, which
articulates with a single ver-
tebra, this ligament does not
present a distinct division
into three fasciculi ; its fibres,
however, radiate, and are at-
tached to the body of the last cervical vertebra, as well as to the body of the
vertebra with which the rib articulates. In the tenth, eleventh, and twelfth ribs
also, which likewise articulate with a single vertebra, the division does not exist;
but the fibres of the ligament in each case radiate and are connected with the
vertebra above, as well as that with which the ribs articulate.
The Capsular Ligament (capsula articularis) is a thin and loose ligamentous bag,
which surrounds the joint between the head of the rib and the articular cavity
formed by the intervertebral disk and the adjacent vertebra. It is very thin,
firmly connected with the anterior ligament, and most distinct at. the upper and
lower parts of the articulation. Behind, some of its fibres pass through the inter-
vertebral foramen to the back of the intervertebral disk. This is the analogue of
the ligamentum conjugate of some mammals, which unites the heads of opposite
ribs across the back of the intervertebral disk.
The Interarticular Ligament (ligamentum capituli costce interarticulare) (Figs. 208
and 209) is situated in the interior of the joint. It consists of a short band of
fibres, flattened from above downward, attached by one extremity to the sharp
crest which separates the two articular facets on the head of the rib, and by the
other to the intervertebral disk. It divides the joint into two cavities, which
have no communication with each other. In the first, tenth, eleventh, and
FIG. 208. — Ribs and corresponding vertebral bodies with their
ligaments, viewed from the right. (Spalteholz.)
ARTICULATIONS OF THE RIBS WITH THE VERTEBRA 287
twelfth ribs the interarticular ligament does not exist; consequently there is but
one synovial membrane.
Synovial Membranes (Figs. 208 and 209). — There are two synovial membranes
in each of the articulations in which there is an interarticular ligament, one on
each side of this structure.
2. ARTICULATIONS OF THE NECKS AND TUBERCLES OF THE RIBS WITH THE
TRANSVERSE PROCESSES OR THE COSTO-TRANSVERSE ARTICULATIONS
(ARTICULATIONES COSTOTRANSVERSARIAE) (Fig. 209).
The articular portion of the tubercle of the rib and adjacent transverse process
form an arthrodial joint.
In the eleventh and twelfth ribs this articulation is wanting.
The ligaments connecting these parts are the
Anterior Superior Costo-transverse. Posterior Costo-transverse
Middle Costo-transverse (Interosseous). Capsular.
The Anterior Superior or Long Costo-transverse Ligament (ligamentum costo-
transversarium anterius) (Figs. 207,208,209, and 210) consists of two sets of fibres:
the one (anterior) is attached below to the sharp crest on the upper border
INTERARTICULAR
LIGAMENT
ANTERIOR COSTO-THANSVERSE
UIQAMENT DIVIDED.
MIDDLE COSTO-TRANSVERSE
Or INTEROSSEOUS
POSTERIOR COSTO-
TRANSVERSE LIGAMENT.
FIG. 209. — Costo-transverse articulation. Seen from above.
of the neck of each rib, and passes obliquely upward and outward to the lower
border of the transverse process immediately above; the other (posterior) is
attached below to the neck of the rib, and passes upward and inward to the base
of the transverse process and outer border of the lower articular process of the
vertebra above. This ligament is in relation, in front, with the intercostal vessels
and nerves; behind, with the Longissimus dorsi muscle. Its internal border is
thickened and free, and bounds an aperture through which pass the posterior
branches of the intercostal vessels and nerves. Its external border is continuous
with a thin aponeurosis which covers the External intercostal muscle.
The first rib has no anterior costo-transverse ligament. In the twelfth rib the
ligament is absent or is a mere vestige.
288
THE ARTICULATIONS OR JOINTS
The Middle Costo-transverse or Interosseous Ligament (ligamentum colli costae)
(Fig. 209) consists of short but strong fibres which pass between the rough sur-
face on the posterior part of the neck of each rib and the anterior surface of the
adjacent transverse process. In order fully to expose this ligament, a horizontal
section should be made across the transverse process and corresponding part of
the rib; or the rib may be forcibly separated from the transverse process and the
fibres of the ligament put on the stretch.
In the eleventh and twelfth ribs this ligament is quite rudimentary or wanting.
The Posterior Costo-transverse Ligament (ligamentumcostotransversarium posterius)
(Fig. 209) is a short but thick and strong fasciculus which passes obliquely from the
summit of the transverse
process to the rough non-
articular portion of the
tubercle of the rib. This
ARTICULAR SURFACE £
FOR TUBERCLE at
OF RIB
o SUPERIOR ARTICULAR
SURFACE FOR HEAD
RIB
ANTERIOR
COSTO-TRANS-
VERSE LIGAMENT
INTERTRANS-
VERSE LIGAMENT
ligament is shorter and
INTERVERTC-
BRAL FIBRO-
CARTILAGE
more oblique in the upper
than in the lower ribs.
Those corresponding to
the superior ribs ascend,
while those of the inferior
ribs descend slightly.
In the eleventh and
twelfth ribs this ligament
is wanting.
The Capsular Ligament
(capsula articularis) is a
thin, membranous sac at-
tached to the circumfer-
ence of the articulari sur-
faces, and enclosing a
small synovial membrane.
In the eleventh and
twelfth ribs this ligament
is absent.
Actions.— The heads of
the ribs are so closely
connected to the bodies
of the vertebrae by the
stellate and interarticular
ligaments, and the necks
and tubercles of the ribs to the transverse processes, that only a slight sliding
movement of the articular surfaces on each other can take place in these articula-
tions. The result of this gliding movement with respect to the six upper ribs con-
sists in an elevation of the front and middle portion of the rib, the hinder part
being prevented from performing any upward movement by its close connection
with the spine. In this gliding movement the rib rotates on an axis corresponding
with a line drawn through the two articulations, costo-central and costo-transverse,
which the rib forms with the spine. With respect to the seventh, eighth, ninth, and
tenth ribs, each one, besides rotating in a similar manner to the upper six, also
rotates on an axis corresponding with a line drawn from the head of the rib to the
sternum. By the first movement — that of rotation of the rib on an axis correspond-
ing with a line drawn through the two articulations which this bone forms with
the spine — an elevation of the anterior part of the rib takes place, and a consequent
enlargement of the antero-posterior diameter of the chest. None of the ribs lie in
INFERIOR ARTICULAR
SURFACE FOR HEAD
OF RIB
INFERIOR ARTIC-
ULAR PROCESS
FIG. 210. — Ribs and corresponding vertebra with ligaments, viewed
from the right. (Spalteholz.)
ARTICULATION OF CARTILAGES OF RIBS WITH STERNUM 289
a truly horizontal plane; they are all directed more or less obliquely, so that their
anterior extremities lie on a lower level than their posterior, and this obliquity
increases from the first to the seventh, and then again decreases. If we examine
any one rib — say, that in which there is the greatest obliquity — we shall see that
it is obvious that as its sternal extremity is carried upward, it must also be thrown
forward ; so that the rib may be
regarded as a radius moving on
the vertebral joint as a centre, and
causing the sternal attachment to
describe an arc of a circle in the
vertical plane of the body. Since
all the ribs are oblique and con-
nected in front to the sternum by
the elastic costal cartilages, they
must have a tendency to thrust
the sternum forward, and so in-
crease the antero-posterior diam-
eter of the chest. By the second
movement — that of the rotation
of the rib on an axis correspond-
ing with a line drawn from the
head of the rib to the sternum —
an elevation of the middle portion
of the rib takes place, and conse-
quently an increase in the trans-
verse diameter of the chest. For
the ribs not only slant downward
and forward from their vertebral
attachment, but they are also ob-
lique in relation to their transverse
plane — that is to say, their middle
is on a lower level than either
their vertebral or sternal extremi-
ties. It results from this that when
the ribs are raised, the centre por-
tion is thrust outward, somewhat
after the fashion in which the
handle of a bucket is thrust away
from the side when raised to a
horizontal position, and the lateral
diameter of the chest is increased
(see Fig. 211). The mobility of the different ribs varies very much. The first rib
is more fixed than the others, on account of the weight of the upper extremity and
the strain of the ribs beneath ; but on the freshly dissected thorax it moves as freely
as the others. From the same causes the movement of the second rib is also not
very extensive. In the other ribs this mobility increases successively down to the
last two, which are very movable. The ribs are generally more movable in the
female than in the male.
VII. Articulation of the Cartilages of the Ribs with the Sternum, etc., or
the Costo-sternal Articulations (Articulationes
Sternocostales) (Fig. 212).
The articulations of the cartilages of the true ribs with the sternum are arthro-
dial joints, with the exception of the first, in which the cartilage is almost always
19
FIG. 211. — Diagrams showing the axis of rotation of the
ribs in the movements of respiration. The one axis of rota-
tion corresponds with the line drawn through the two articu-
lations which the rib forms with the spine (a, b), and the other
with a line drawn from the head of the rib to the sternum
(A, B). (From Kirke's Handbook of Physiology.)
290 THE ARTICULATIONS OR JOINTS
directly united with the sternum, and which must therefore be regarded as a
synarthrodial articulation. The ligaments connecting them are the
Anterior Chondro-sternal. Capsular.
Posterior Chondro-sternal. Interarticular Chondro-sternal.
Chondro-xiphoid.
The Anterior Chondro-sternal or Sterno-costal Ligament (ligamentum sternocostale
radiatum) (Fig. 212) is a broad and thin membranous band that radiates from
the front of the inner extremity of the cartilages of the true ribs to the anterior
surface of the sternum. It is composed of fasciculi which pass in different direc-
tions. The superior fasciculi ascend obliquely, the inferior fasciculi pass obliquely
downward, and the middle fasciculi pass horizontally. The superficial fibres of this
ligament are the longest: they intermingle with the fibres of the ligaments above
and below them, with those of the opposite side, and with the tendinous fibres of
origin of the Pectoralis major, forming a thick fibrous membrane which covers
the surface of the sternum (membrana sterni}. This is more distinct at the lower
than at the upper part. According to the modern nomenclature, this ligament
and the posterior chondro-sternal ligament are called ligamenta sternocostalia
radiata. The two chondro-sternal ligaments form a sheath for the sternum
anteriorly and posteriorly, the membrana sterni.
The Posterior Chonjiro-sternal or Sterno-costal Ligament (ligamentum sterno-
costale radiatum), less thick and distinct than the anterior, is composed of fibres
which radiate from the posterior surface of the sternal end of the cartilages of
the true ribs to the posterior surface of the sternum, becoming blended with the
periosteum.
The Capsular Ligament (capsula articidaris) surrounds the joint formed between
the cartilage of a true rib and the sternum. It is very thin, intimately blended
with the anterior and posterior ligaments, and strengthened at the upper and lower
part of the articulation by a few fibres which pass from the cartilage to the side
of the sternum. These ligaments protect the synovial membranes.
The Interarticular Chondro-sternal or Sterno-costal Ligament (ligamentum sterno-
costale inter articular e] (Fig. 212). — This is found between the second costal car-
tilage and the sternum. The cartilage of the second rib is connected with the
sternum by means of an interarticular ligament attached by one extremity to the
cartilage of the second rib, and by the other extremity to the cartilage which unites
the first and second pieces of the sternum. This articulation is provided with two
synovial membranes. The cartilage of the third rib is also connected with the ster-
num by means of an interarticular ligament which is attached by one extremity to
the cartilage of the third rib, and by the other extremity to the point of junction
of the second and third pieces of the sternum. This articulation may be provided
with two synovial membranes. In the other joints interarticular ligaments may
exist, but they rarely completely divide the joint into two cavities.
The Anterior Chondro-xiphoid or Costo-xiphoid Ligament (ligamentum costo-
xiphoidea) (Fig. 212).— This is a band of ligamentous fibres which connects
the anterior surface of the seventh costal cartilage, and occasionally also that
of the sixth, to the anterior surface of the ensiform appendix. It varies in
length and breadth in different subjects. A similar band of fibres on the inter-
nal or posterior surface, though less thick and distinct, may be demonstrated.
It is spoken of as the posterior chondro-xiphoid or costo -xiphoid ligament.
Synovial Membranes (Fig. 212). — There' is no synovial membrane between the
first costal cartilage and the sternum, as this cartilage is directly continuous with
the sternum. There are two synovial membranes, both in the articulation of the
second and third costal cartilages to the sternum. There is generally one syno-
vial membrane in each of the joints between the fourth, fifth, sixth, and seventh
ARTICULATION OF CARTILAGES OF RIBS WITH STERNUM 291
costal cartilages to the sternum; but it is sometimes absent in the sixth and
seventh chondro-sternal joints. Thus there are usually eight synovial cavities on
each side in the articulations between the costal cartilages of the true ribs and
the sternum. After middle life the articular surfaces lose their polish, become
FIG. 212. — Sternum and ribs with ligaments, from in front. In the left half of the figure the most anterior
layer has been removed and the joint slits have been opened ; the parts are separated somewhat from one
another on the left side. (Spalteholz.)
roughened, and the synovial membranes appear to be wanting. In old age the
articulations do not exist, the cartilages of most of the ribs becoming continuous
with the sternum.
Actions. — The movements which are permitted in the chondro-sternal articu-
lations are limited to elevation and depression, and these only to a slight extent.
Articulations of the Cartilages of the Ribs with Each Other or the Inter-
chondral Articulations (articidationes interchondrales) (Fig. 212). — The con-
292 THE ARTICULATIONS OR JOINTS
tiguous borders of the sixth, seventh, and eighth, and sometimes the ninth and
tenth, costal cartilages articulate with each other by small, smooth, oblong-shaped
facets. Each articulation is enclosed in a thin capsular ligament lined by syno-
vial membrane, and strengthened externally and internally by ligamentous fibres,
external and internal interchondral ligaments (ligamenta intercostalia externa et
internet), which pass from one cartilage to the other. Sometimes the fifth costal
cartilage, more rarely that of the ninth, articulates, by its lower border, with the
adjoining cartilage by a small oval facet; more frequently they are connected
together by a few ligamentous fibres. Occasionally the articular surfaces' above
mentioned are wanting.
Articulations of the Ribs with their Cartilages or the Costo-chondral
Articulations (Fig. 212). — The outer extremity of each costal cartilage is re-
ceived into a depression in the sternal ends of the ribs, and the two are held
together by the periosteum. There is no real joint. Occasionally a synovial
membrane exists between the first rib and the corresponding cartilage.
VIII. Articulations of the Sternum (Fig. 212).
The first piece of the sternum is united to the second either by an amphi-
arthrodial joint — a single piece of true fibre-cartilage uniting the segments — or
by a diarthrodial joint, in which each bone is clothed with a distinct lamina of
cartilage, adherent on one side, free and lined with synovial membrane on the
other. In the latter case the cartilage covering the gladiolus is continued without
interruption on to the cartilages of the second ribs. Mr. Rivington has found the
diarthrodial form of joint in about one-third of the specimens examined by him ;
Mr. Maisonneuve more frequently. It appears to be rare in childhood, and is
formed, in Mr. Rivington's opinion, from the amphiarthrodial form by absorption.
The diarthrodial joint seems to have no tendency to ossify at any age, while the
amphiarthrodial is more liable to do so, and has been found ossified as early as
thirty-four years of age. Professor Cunningham1 says : " It is not usual to find the
manubri-gladiolar joint obliterated by the ossification of the two bony segments.
Even in advanced life it remains open, and the joint partakes of the nature of"
an amphiarthrosis, although a joint cavity is not found under any circumstances
in the plate of fibro-cartilage which intervenes between the manubrium and the
gladiolus.'' The two segments are further connected by an
Anterior Intersternal Ligament. Posterior Intersternal Ligament.
The Anterior Intersternal Ligament consists of a layer of fibres, having a longi-
tudinal direction; it blends with the fibres of the anterior chondro-sternal liga-
ments on both sides (membrani sterni), and with the tendinous fibres of origin
of the Pectoralis major muscle. This ligament is rough, irregular, and much
thicker below than above.
The Posterior Intersternal Ligament is disposed in a somewhat similar manner
on the posterior surface of the articulation.
IX. Articulation of the Vertebral Column with the Pelvis.
The ligaments connecting the last lumbar vertebra with the sacrum are similar
to those which connect the segments of the spine with each other— viz.: 1. The
continuation downward of the anterior and posterior common ligaments. 2. The
intervertebral substance connecting the flattened oval surfaces of the two bones
1 Text-book of Anatomy, p. 264.
ARTICULATION OF VERTEBRAL COLUMN WITH PELVIS 293
and forming an amphiarthrodial joint. 3. Ligamenta subflava, connecting the
arch of the last lumbar vertebra with the posterior border of the sacral canal.
4. Capsular ligaments connecting the articulating processes and forming a double
arthrodia. 5. Inter- and supraspinous ligaments.
The two proper ligaments connecting the pelvis with the spine are the lumbo-
sacral and ilio-lumbar.
The Lumbo -sacral Ligament (Fig. 213) is a short, thick, triangular fascic-
ulus, which is connected above to the lower and front part of the trans-
verse process of the last lumbar vertebra, passes obliquely outward, and is
attached below to the lateral surface of the base of the sacrum. It is closely
blended with the anterior sacro-iliac ligament and with the ilio-lumbar
ligament, and is to be regarded as a portion of the ilio-lumbar ligament.
This ligament is in relation, in front, with the Psoas muscle. The in-
ternal border of the lumbo-sacral ligament margins the foramen of the last
lumbar nerve.
The Ilio-lumbar Ligament (ligamentum iliolumbale) (Fig. 213) passes horizon-
tally outward from the apex of the transverse process of the last lumbar vertebra
Aperture of communication
with
PSOAS anil ILIACUS.
Femur.
FIG. 213. — Articulations of the pelvis and hip. Anterior view.
to the crest of the ilium immediately in front of the sacro-iliac articulation. It
is of a triangular form, thick and narrow internally, broad and thinner exter-
nally. It is in relation, in front, with the Psoas muscle ; behind, with the
muscles occupying the vertebral groove; above, with the Quadratus lum-
borum. It blends in places with the lumbo-sacral ligament, and its cres-
centic inner margin marks the limit of the foramen for the fourth lumbar nerve.
These ligaments are thick prolongations from, the anterior layer of the lumbar
fascia.
294 THE ARTICULATIONS OB, JOINTS
X. Articulations of the Pelvis.
The ligaments connecting the bones of the pelvis with each other may be
divided into four groups: 1. Those connecting the sacrum and ilium. 2. Those
passing between the sacrum and ischium. 3. Those connecting the sacrum and
coccyx. 4. Those between the two pubic bones.
1. ARTICULATION OF THE SACRUM AND ILIUM (ARTICULATIO SACROILIACA.)
The sacro-iliac articulation is an amphiarthrodial joint, formed between the
lateral surfaces of the sacrum and ilium. The anterior or auricular portion of each
articular surface is covered with a thin plate of cartilage, thicker on the sacrum
than on the ilium. These are in close contact with each other, and to a certain
extent united together by irregular patches of softer fibro-cartilage, and at their
upper and posterior part by fine fibres of interosseous fibrous tissue. Throughout
a considerable part of their extent, especially in advanced life, they are not
connected together, but are separated by a space containing a synovial-like fluid,
and hence the joint presents the characters of a diarthrosis.
The ligaments connecting these surfaces are the
Anterior Sacro-iliac. Posterior Sacro-iliac.
Interosseous.
The Anterior Sacro-iliac Ligaments (lig amenta sacroiliaca anterior a) (Fig. 213)
consists of numerous thin bands which connect the anterior surfaces of the sacrum
and ilium.
The Posterior Sacro-iliac Ligament (ligamentum sacroiliacum posterius) (Fig. 214)
is a strong interosseous ligament, situated in a deep depression between the sacrum
and ilium behind, and forming the chief bond of connection between those bones.
It consists of numerous strong fasciculi which pass between the bones in various
directions. Three of these are of large size: the two superior fasciculi constitute
the short sacro-iliac ligament (ligamentum sacroiliacum posterius breve) . They are
nearly horizontal in direction, arise from the first and second transverse tuber-
cles on the posterior surface of the sacrum, and are inserted into the rough,
uneven surface at the posterior part of the inner surface of the ilium. The
third fasciculus, oblique in direction, is attached by one extremity to the third
transverse tubercle on the posterior surface of the sacrum, and by the other to
the posterior superior spine of the ilium; it is sometimes called the long or oblique
sacro-iliac ligament (ligamentum sacroiliacum posterius longum).
The Interosseous Ligaments (ligamenta sacroiliaca interossed) are completely
covered by the posterior sacro-iliac ligament, and are not visible when the joint
is unopened. The fibres are short and run obliquely and completely fill the
hollow which exists posterior to the joint.
The position of the sacro-iliac joint is indicated by the posterior superior spine of the ilium.
This process is immediately behind the centre of the' articulation.
2. LIGAMENTS PASSING BETWEEN THE SACRUM AND ISCHIUM (Fig. 214).
The Great Sacro-sciatic (Posterior).
The Lesser Sacro-sciatic (Anterior).
The Great or Posterior Sacro-sciatic Ligament (ligamentum sacroiuberosum} (Figs.
214 and 215) is situated at the lower and back part of the pelvis. It is flat, and
triangular in form; narrower in the middle than at the extremities; attached by its
broad base to the posterior inferior spine of the ilium, to the fourth and fifth trans-
ARTICULATIONS OF THE PELVIS
295
verse tubercles of the sacrum, and to the lower part of the lateral margin of that bone
and the coccyx. Passing obliquely downward, outward, and forward, it becomes
narrow and thick, and at its insertion into the inner margin of the tuberosity of
the ischium it increases in breadth, and is prolonged forward along the inner
margin of the ramus, forming what is known as the falciform process of the
great sacro-sciatic ligament or the falciform ligament (processus falciformis) . The
free concave edge of this prolongation has attached to it the obturator fascia,
with which it forms a kind of groove, protecting the internal pudic vessels and
nerve. One of its surfaces is turned toward the perinosum, the other toward
the Obturator internus muscle.
r
S^.
•emur,
FIG. 214. — Articulations of pelvis and hip. Posterior view.
The posterior surface of this ligament gives origin, by its whole extent, to fibres
of the Gluteus maximus muscle. Its anterior surface is united to the lesser sacro-
sciatic ligament. Its external border forms, above, the posterior boundary of the
great sacro-sciatic foramen, and, below, the posterior boundary of the lesser sacro-
sciatic foramen. Its lower border forms part of the boundary of the perinaeum. It
is pierced by the coccygeal branch of the sciatic artery and the coccygeal nerve.
The Lesser or Anterior Sacro-sciatic Ligament (ligamentum sacrospinosum) (Figs.
214 and 215), much shorter and smaller than the preceding, is thin, triangular in
form, attached by its apex to the spine of the ischium, and internally, by its broad
base, to the lateral margin of the sacrum and coccyx, anterior to the attachment
of the great sacro-sciatic ligament, with W7hich its fibres are intermingled.
It is in relation, anteriorly, with the Coccygeus muscle; posteriorly, it is covered
by the great sacro-sciatic ligament and crossed by the intecnal pudic vessels and
nerve. Its superior border forms the lower boundary of the great sacro-sciatic
foramen; its inferior border, part of the lesser sacro-sciatic foramen.
296
THE ARTICULATIONS OR JOINTS
These two ligaments convert the sacro-sciatic notches into foramina. The
superior or great sacro-sciatic foramen (foramen ischiadicum majus) (Figs. 214 and
215) is bounded, in front and above, by the posterior border of the os innominatum;
behind, by the great sacro-sciatic ligament; and below, by the lesser sacro-sciatic
ligament. It is partially filled up, in the recent state, by the Pyriformis muscle,
which passes through it. Above this muscle the gluteal vessels and superior gluteal
nerve emerge from the pelvis, and, below it, the sciatic vessels and nerves, the inter-
nal pudic vessels and nerve, the inferior gluteal nerve, and the nerves to the obtu-
rator internus and quadratus femoris. The inferior or lesser sacro-sciatic foramen
(foramen ischiadicum minus) (Figs. 214 and 215) is bounded, in front, by the
POUPART'S
LIGAMENT
ANT. SACRO-ILIAC
LIGAMENT.
GREAT SACRO-
SCIATIC LIGA-
MENT.
LESSER SACRO-
SCIATIC LIGA-
MENT.
GREAT SACRO-
SCIATIC LIGA-
MENT.
Obturato
membrane.
FIG. 215. — Side view of pelvis, showing the greater and lesser sacro-sciatic ligaments.
tuber ischii; above, by the spine and lesser sacro-sciatic ligament; behind, by the
greater sacro-sciatic ligament. It transmits the tendon of the Obturator internus
muscle, its nerve, and the internal pudic vessels and nerve.
3. ARTICULATION OF THE SACRUM AND COCCYX (SYMPHYSIS SACROCOCCYGEA) .
This articulation is an amphiarthrodial joint, formed between the oval surface
at the apex of the sacrum and the base of the coccyx. It is analogous to the
joints between the bodies of the vertebrae. The ligaments are the
Anterior Sacro-coccygeal.
Posterior Sacro-coccygeal.
Lateral Sacro-coccygeal.
Interposed Fibro-cartilage.
The Anterior Sacro-coccygeal Ligament (ligamentum sacrococcygeum anterius)
consists of a few irregular fibres which descend from the anterior surface of the
sacrum to the front of tfre coccyx, becoming blended with the periosteum. It is
a continuation of the anterior common ligament.
The Posterior Sacro-coccygeal Ligament (ligamentum sacrococcygeum posterius)
(Fig. 216) is divided into two portions, the deep and the superficial. The deep
ARTICULATIONS OF THE PELVIS 297
portion of the posterior sacro-coccygeal ligament (ligamentum sacrococcygeum posterius
profundwn) , which is a continuation of the posterior common ligament, is a flat
band of a pearly tint, which arises from the margin of the lower orifice of the sacral
canal, and descends to be inserted into the posterior surface of the coccyx. This
ligament completes the lower and back part of the sacral canal. Its superficial
fibres are much longer than the more deeply seated. This ligament is in rela-
tion, behind, with the Gluteus maximus.
The superficial portion of the posterior sacro-coccygeal ligament (ligamentum
sacrococcygeum posterius superficiale) is composed of longitudinal fibrous bands
which extend from the lower portion of the middle sacral ridge to the posterior
surface of the coccyx and closes partly the hiatus sacralis ; and of fibrous bands
which extend from the sacral cornua to the coccygeal cornua. A portion of this
ligament corresponds to the ligamenta subflava and the balance to the capsular
ligament.
A Lateral Sacro-coccygeal or Intertransverse Ligament (ligamentum sacrococcygeum
later ale) (Fig. 216) connects the transverse process of the coccyx to the lower
lateral angle of the sacrum on each side.
APEX OF SACRUM
LATERAL SACRO-
COCCYGEAL LIGAMENT
SUPERFICIAL PORTION OF POST
SACRO-COCCYGEAL LIGAMENT
DEEP PORTION OF POSTERIOR
SACRO-COCCYGEAL LIGAMENT
FIG. 216. — Ligaments between the sacrum and the coccyx. (Spalteholz.)
A Fibro-cartilage is interposed between the contiguous surfaces of the sacrum
and coccyx; it differs from that interposed between the bodies of the vertebrae in
being thinner, and its central part firmer in texture. It is somewhat thicker in
front and behind than at the sides. Occasionally, a synovial membrane is found
and the coccyx is freely movable. This is especially the case during pregnancy.
The different segments of the coccyx are connected together by an extension
downward of the anterior and posterior sacro-coccygeal ligaments, a thin annular
disk of fibro-cartilage being interposed between each of the bones. In the adult
male all the pieces become ossified, but in the female this does not commonly
occur until a later period of life. The separate segments of the "coccyx are first
united, and at a more advanced age the joint between the sacrum and coccyx is
obliterated.
Actions. — The movements which take place between the sacrum and coccyx,
and between the different pieces of the latter bone, are forward and backward,
and are very limited. Their extent increases during pregnancy.
298
THE ARTICULATIONS OR JOINTS
Hyaline cartilage covering lone.
Intermediate fibro-cartilage.
Cavity at upper
and back part
4. ARTICULATION OF THE OSSA PUBIS (SYMPHYSIS OSSIUM PUBIS) (Figs. 213, 217).
The articulation between the pubic bones is an amphiarthrodial joint, formed
by the junction of the two oval articular surfaces of the ossa pubis. The liga-
ments of this articulation are the
Anterior Pubic. Superior Pubic.
Posterior Pubic. Inferior Pubic.
Interpubic Disk.
The Anterior Pubic Ligament (ligamentum pubicum anterius) (Fig. 213) consists
of several superimposed layers which pass across the front of the articulation. The
superficial fibres pass obliquely from one bone to the other, decussating and form-
ing an interlacement with the fibres of the aponeurosis of the External oblique and
the tendon of the Rectus muscles. The deep fibres pass transversely across the
symphysis, and are blended with the fibro-cartilage.
The" Posterior Pubic Ligament (ligamentum pubicum posterius) consists of a
few thin, scattered fibres which unite the two pubic bones posteriorly.
The Superior Pubic Ligament (liga-
mentum pubicum super ius) (Fig. 213)
is a band of fibres which connects to-
gether the two pubic bones superiorly.
The Inferior Pubic or Subpubic
Ligament (ligamentum arcuatum
pubis) (Fig. 213) is a thick, tri-
angular arch of ligamentous fibres,
connecting together the two pubic
bones below and forming the upper
boundary of the pubic arch. Above,
it is blended with the interarticular
fibro-cartilage; laterally it is united
with the descending rami of the
pubis. Its fibres are closely con-
nected and have an arched direction.
Its lower margin is separated from
the triangular ligament of the per-
imeum by a gap, through which runs
the dorsal vein of the penis.
The Interpubic Disk (lamina fibrocartilaginea interpubicd) (Fig. 217) consists of a
disk of cartilage and fibro-cartilage connecting the surfaces of the pubic bones in
front. Each of the two surfaces is covered by a thin layer of hyaline cartilage which
is firmly connected to the bone by a series of nipple-like processes which accu-
rately fit within corresponding depressions on the osseous surfaces. These opposed
cartilaginous surfaces are connected together by an intermediate stratum of fibrous
tissue and fibro-cartilage which varies in thickness in different subjects. It often
contains a cavity (cavum articulare) in its centre, probably formed by the soften-
ing and absorption of the fibro-cartilage, since it rarely appears before the tenth
year of life, and is not lined by synovial membrane. It is larger in the female
than in the male, but it is very questionable whether it enlarges, as was formerly
supposed, during pregnancy. It is most frequently limited to the upper and back
part of the joint, but it occasionally reaches to the front, and may extend the
entire length of the cartilage. This cavity may be easily demonstrated by making
a vertical section of the symphysis pubis near its posterior surface (Fig. 217).
The Obturator Ligament is more properly regarded as analogous to the muscular
fasciae, with which it will be described.
FIG. 217. — Vertical section of the symphysis pubis.
Made near its posterior surface.
STERNO-CLA VICULAR ARTICULA TION
299
ARTICULATIONS OF THE UPPER EXTREMITY.
The articulations of the upper extremity may be arranged in the following
groups :
I. Sterno-clavicular Articulation.
II. Acromio-clavicular Articulation.
III. Ligaments of the Scapula.
IV. Shoulder-joint.
V. Elbow-joint.
VI. Radio-ulnar Articulations.
VII. Wrist-joint.
VIII. Articulations of the Carpal Bones.
IX. Carpo-metacarpal Articulations.
X. Metacarpo-phalangeal Articula-
tions.
XI. Articulations of the Phalanges.
I. Sterno-clavicular Articulation (Articulatio Sternoclavicularis) (Fig. 218).
The sterno-clavicular is regarded by most anatomists as an arthrodial joint,
but Cruveilhier considers it to be an articulation by reciprocal reception. Probably
FIG. 218. — Sterno-clavicular articulation. Anterior view.
the former opinion is the correct one, the varied movement which the joint enjoys
being due to the interposition of an interarticular fibro-cartilage between the
joint surfaces. The parts entering into its formation are the sternal end of the
clavicle, the upper and lateral part of the first piece of the sternum, and the
cartilage of the first rib. The articular surface of the sternum is covered with
cartilage. The articular surface of the clavicle is much larger than that of the
sternum, and invested with a layer of cartilage1 which is considerably thicker than
that on the latter bone. The ligaments of this joint are the
Capsular.
Anterior Sterno-clavicular.
Posterior Sterno-clavicular.
Interclavicular.
Costo-clavicular.
Interarticular Fibro-cartilage.
The Capsular Ligament (capsida articularis) completely surrounds the articula-
tion, consisting of fibres of varying degrees of thickness and strength. Those in
front and behind are of considerable thickness, and form the anterior and posterior
sterno-clavicular ligaments; but those above and below, especially in the latter
situation, are thin and scanty, and partake more of the character of connective
tissue than true fibrous tissue.
1 Accprding to Bruch, the sternal end of the clavicle is covered by a tissue which is rather fibrous than
cartilaginous in structure. — ED. of 15th English Edition.
300 THE ARTICULATIONS OR JOINTS
The Anterior Sterno -clavicular Ligament (ligamentum sternoclaviculare) (Fig. 218)
is a part of the capsule. It is a broad band of fibres which covers the anterior sur-
face of the articulation, being attached, above, to the upper and front part of the
inner extremity of the clavicle, and, passing obliquely downward and inward,
is attached, below, to the upper and front part of the first piece of the sternum.
This ligament is covered, in front, by the sternal portion of the Sterno-cleido-
mastoid and the integument; behind, it is in relation with the interarticular
fibre-cartilage and the two synovial membranes.
The Posterior Sterno -clavicular Ligament, also a part of the capsule, is a band of
fibres which covers the posterior surface of the articulation, being attached, above,
to the upper and back part of the inner extremity of the clavicle, and, passing
obliquely downward and inward, is attached, below, to the upper and back part
of the first piece of the sternum. It is in relation, in front, with the interartic-
ular fibro-cartilage and synovial membranes; behind, with the Sterno-hyoid and
Sterno-thyroid muscles.
The Interclavicular Ligament (ligamentum interdaviculare) (Fig. 218) is a flat-
tened band which varies considerably in form and size in different individuals; it
passes in a curved direction from the upper part of the inner extremity of one
clavicle to the other, and is also attached to the upper margin of the sternum. It
is in relation, in front, with the integument; behind, with the Sterno-thyroid
muscles.
The Costo-clavicular or Rhomboid Ligament (ligamentum costoclaviculare)
(Fig. 218) is short, flat, and strong; it is of a rhomboid form, attached, below, to
the upper and inner part of the cartilage of the first rib : it ascends obliquely back-
ward and outward, and is attached, above, to the rhomboid depression on the
under surface of the clavicle. It is in relation, in front, with the tendon of
origin of the Subclavius; behind, with the subclavian vein.
The Interarticular Fibro-cartilage (discus articularis) (Fig. 218) is a flat and nearly
circular meniscus, interposed between the articulating surfaces of the sternum and
clavicle. It is attached, above, to the upper and posterior border of the articular
surface of the clavicle; below, to the cartilage of the first rib, at its junction with the
sternum ; and by its circumference, to the anterior and posterior sterno-clavicular
and the interclavicular ligaments. It is thicker at the circumference, especially
its upper and back part, than at its centre or below. It divides the joint into two
cavities, each of which is furnished with a separate synovial membrane.
Synovial Membrane. — Of the two synovial membranes found in this articulation,
one is reflected from the sternal end of the clavicle over the adjacent surface of the
fibro-cartilage and cartilage of the first rib ; the other is placed between the articular
surface of the sternum and adjacent surface of the fibro-cartilage; the latter is the
larger of the two.
Actions. — This articulation is the centre of the movements of the shoulder, and
admits of a limited amount of motion in nearly every direction — upward, down-
ward, backward, forward — as well as circumduction. When these movements take
place in the joint, the clavicle in its motion carries the scapula with it, this bone
gliding on the outer surface of the chest. This joint therefore forms the centre
from which all movements of the supporting arch of the shoulder originate, and
is the only point of articulation of this part of the skeleton with the trunk. "The
movements attendant on elevation and depression of the shoulder take place
between the clavicle and the interarticular fibro-cartilage, the bone rotating upon
the ligament on an axis drawn from before backward through its own articular
facet. When the shoulder is moved forward and backward, the clavicle, with
the interarticular fibro-cartilage, rolls to and fro on the articular surface of the
sternum, revolving, with a sliding movement, round an axis drawn nearly vertically
through the sternum. In the circumduction of the shoulder, which is compounded
ACROMIO-CLAVICULAR ARTICULATION 301
of these two movements, the clavicle revolves upon the interarticular fibre-carti-
lage, and the latter, with the clavicle, rolls upon the sternum."1 Elevation of the
clavicle is principally limited by the costo-clavicular ligament; depression by the
interclavicular. The muscles which raise the clavicle, as in shrugging the shoulder,
are the upper fibres of the Trapezius, the Levator anguli scapula*, the clavicular
head of the Sterno-mastoid, assisted to a certain extent by the two Rhomboids,
which pull the vertebral border of the Scapula backward and upward, and so
raise the clavicle. The depression of the clavicle is principally effected by gravity,
assisted by the Subclavius, Pectoralis minor, and lower fibres of the Trapezius.
It is drawn backward by the Rhomboids and the middle and lower fibres of the
Trapezius; and forward by the Serratus magnus and Pectoralis minor.
Surface Form. — The position of the sterno-clavicular joint may be easily ascertained by feel-
ing the enlarged sternal end of the collar-bone just external to the long, cord-like, sternal origin
of the Sterno-mastoid muscle. If this muscle is relaxed by bending the head forward, a depres-
sion just internal to the end of the clavicle, and between it and the sternum, can be felt, indi-
cating the exact position of the joint, which is subcutaneous. When the arm hangs by the side,
the cavity of the joint is V-shaped. If the arm is raised, the bones become more closely approx-
imated, and the cavity becomes a mere slit.
Surgical Anatomy. — The strength of this joint mainly depends upon its ligaments, and
it is because of the ligaments and because the force of a blow is generally transmitted along the
long axis of the clavicle, that dislocation so rarely occurs, and that the bone is generally broken
rather than displaced. When dislocation does occur, the course which the displaced bone takes
depends more upon the direction in which the violence was applied than upon the anatomical
construction of the joint; it may be either forward, backward, or upward. A complete upward
dislocation is also inward. A complete forward or backward dislocation is also inward and
downward. The chief point worthy of note, as regards the construction of the joint, in regard
to dislocations, is the fact that, owing to the shape of the articular surfaces being so little
adapted to each other, and that the strength of the joint mainly depends upon the ligaments,
the displacement when reduced is very liable to recur, and hence it is extremely difficult to
keep the end of the bone in its proper place, and it may be necessary to incise the soft parts
and wire the bone in place.
II. Acromio-clavicular Articulation or Scapulo-clavicular Articulation
(Articulatio Acromioclavicularis) (Fig. 219).
The acromio-clavicular IT an arthrodial joint formed between the outer extrem-
ity of the clavicle and the inner margin of the acromion process of the scapula.
The ligaments which surround the joint form a capsule. The ligaments of this
articulation are the
Superior Acromio-clavicular. f Trapezoid.
Inferior Acromio-clavicular. Coraco-clavicular < and
Interarticular Fibro-cartilage. ( Conoid.
The Superior Acromio-clavicular Ligament (lig amentum acromioclaviculare} (Figs.
219 and 220) is a portion of the joint capsule. It is a quadrilateral band which
covers the superior part of the articulation, extending between the upper part of
the outer end of the clavicle and the adjoining part of the upper surface of the
acromion. It is composed of parallel fibres which interlace with the aponeurosis
of the Trapezius and Deltoid muscles; below, it is in contact with the inter-
articular fibro-cartilage (when it exists) and the synovial membranes.
The Inferior Acromio-clavicular Ligament, somewhat thinner than the pre-
ceding, and like it a portion of the capsule, covers the under part of the articula-
tion, and is attached to the adjoining surfaces of the two bones. It is in relation,
above, with the synovial membranes, and in rare cases with the interarticular
fibro-cartilage; below, with the tendon of the Supraspinatus. These two liga-
1 Humphry. On the Human Skeleton, p. 402.
302
THE ARTICULATIONS OR JOINTS
ments are continuous with each other in front and behind, and form a complete
capsule round the joint.
The Interarticular Fibro-cartilage (discus articularis) is frequently absent in this
articulation. When the meniscus exists it is generally incomplete and only par-
tially separates the articular surfaces, and occupies the upper part of the articu-
lation. More rarely it completely separates the joint into two cavities.
^"•'-•.mrt x-^
'IG. 219. — The left shoulder-joint, scapulo-clavicular articulations, and proper ligaments of scapula.
The Synovial Membrane. — There is usually only one sy no vial membrane in
this articulation, but when a complete interarticular fibre-cartilage exists there are
two synovial membranes.
The Coraco-clavicular Ligament (ligamentum coracoclaviculare) (Figs. 219 and
220) serves to connect the clavicle with the coracoid process of the scapula. It does
not properly belong to this articulation, but as it forms a most efficient means in
retaining the clavicle in contact with the acromial process, it is usually described
with it. It consists of two fasciculi, called the trapezoid and conoid ligaments.
The trapezoid ligament (ligamentum trapezoideum] , the anterior and external
fasciculus, is broad, thin, and quadrilateral; it is placed obliquely between the
coracoid process and the clavicle. It is attached, below, to the upper surface
of the coracoid process ; above, to the oblique line on the under surface of the
•clavicle. Its anterior border is free ; its posterior border is joined with the conoid
ligament, the two forming by their junction a projecting angle.
The conoid ligament (ligamentum conoideum), the posterior and internal fas-
ciculus, is a dense band of fibres, conical in form, the base being directed upward,
the summit downward. It is attached by its apex to a rough impression at the
base of the coracoid process, internal to the preceding; above, by its expanded
PROPER LIGAMENTS OF THE SCAPULA 393
base, to the conoid tubercle on the under surface of the clavicle, and to a line
proceeding internally from it for half an inch. These ligaments are in relation,
in front, with the Subclavius and Deltoid; behind, with the Trapezius. They
serve to limit rotation of the scapula, the Trapezoid limiting rotation forward,
and the Conoid backward.
Actions. — The movements of this articulation are of two kinds: 1. A gliding
motion of the articular end of the clavicle on the acromion. 2. Rotation of the
scapula forward and backward upon the clavicle, the extent of this rotation being
limited by the two portions of the coraco-clavicular ligament.
The acromio-clavicular joint has important functions in the movements of the
upper extremity. It has been well pointed out by Sir George Humphry that if
there had been no joint between the clavicle and scapula the circular movement of
the scapula on the rfbs (as in throwing both shoulders backward or forward) would
have been attended with a greater alteration in the direction of the shoulder than is
consistent with the free use of the arm in such position, and it would have been
impossible to give a blow straight forward with the full force of the arm; that is to
say, with the combined force of the scapula, arm, and forearm. "This joint," as
he happily says, "is so adjusted as to enable either bone to turn in a hinge-like
manner upon a vertical axis drawn through the other, and it permits the surfaces
of the scapula, like the baskets in a roundabout swing, to look the same way in
every position or nearly so." Again, when the whole arch formed by the clavicle
and scapula rises and falls (in elevation or depression of the shoulders), the joint
between these two bones enables the scapula still to maintain its lower part in
contact with the ribs.
Surface Form. — The position of the acromio-clavicular joint can generally be ascertained by
the slightly enlarged extremity of the outer end of the clavicle, which causes it to project above
the level of the acromion process of the scapula. Sometimes this enlargement is so considerable
as to form a rounded eminence, which is easily to be felt. The joint lies in the plane of a ver-
tical line passing up the middle of the front of the arm.
Surgical Anatomy. — Owing to the slanting shape of the articular surfaces of this joint,
the commonest dislocation is the passing of the acromion process of the scapula under the
outer end of the clavicle; but dislocations in the opposite direction have been described. The
first form of dislocation is produced by violent force applied to the scapula so as to drive the
shoulder forward. The displacement in acromio-clavicular dislocation is often incomplete, on
account of the strong coraco-clavicular ligaments which remain untorn. The same difficulty
exists, as in the sterno-clavicular dislocation, in maintaining the ends of the bone in apposition after
reduction, and it may become necessary to wire them in place after incision of the soft parts.
HI. Proper Ligaments of the Scapula (Figs. 219, 220).
The proper ligaments of the scapula pass between portions of that bone, but
are not parts of an articulation. They are the
Coraco-acromial. Superior Transverse.
Inferior Transverse.
The Coraco-acromial Ligament (ligamentum coracoacromiale) is a strong trian-
gular band, extending between the coracoid and acromial processes. It is attached,
by its apex, to the summit of the acromion just in front of the articular surface
for the clavicle, and by its broad base to the whole length of the outer border of
the coracoid process. Its posterior fibres are directed inward, its anterior fibres
forward and inward. This ligament completes the vault formed by the coracoid and
acromion processes for the protection of the head of the humerus. It is in relation,
above, with the clavicle and under surface of the Deltoid muscle ; below, with the
tendon of the Supraspinatus muscle, a bursa being interposed. Its outer border is
continuous with a dense lamina that passes beneath the Deltoid upon the tendons
304
THE ARTICULATIONS OR JOINTS
of the Supra- and Infraspinatus muscles. This,ligament is sometimes described as
consisting of two marginal bands and a thinner intervening portion, the two bands
being attached respectively to the apex and base of the coracoid process, and join-
ing together at their attachment into the acromion process. When the Pectoralis
minor is inserted, as sometimes is the case, into the capsule of the shoulder-joint
instead of into the coracoid process, it passes between these two bands, and the
intervening portion is then deficient.
The Superior Transverse, Coracoid or Suprascapular Ligament (ligamentum trans-
versum scapulae superius) (Figs. 219, 220, and 222) converts the suprascapular
SUPERIOR
ACROMIOCLAVICULAR
LIGAMENT
GLENOID
LIGAMENT
FIG. 220. — Right clavicle and shoulder-blade with ligament, from without and somewhat from in front.
(Spalteholz.,)
notch into a foramen. It is a thin and flat fasciculus, narrower at the middle
than at the extremities, attached by one end to the base of the coracoid process,
and by the other to the inner extremity of the scapular notch. The suprascapular
nerve passes through the foramen; the suprascapular vessels pass over the liga-
ment.
An additional ligament, the Inferior Transverse or Spino-glenoid Ligament (liga-
mentum transversum scapulae inferius), is sometimes found on the scapula, stretch-
ing from the outer border of the spine to the margin of the glenoid cavity. When
present, it forms an arch under which the suprascapular vessels and nerve pass as
they enter the infraspinous fossa.
Movements of Scapula. — The scapula is capable of being moved upward and
downward, forward and backward, or, by a combination of these movements, cir-
cumducted on the wall of the chest. The muscles which raise the scapula are the
upper fibres of the Trapezius, the Levator anguli scapulre, and the two Rhom-
boids; those which depress it are the lower fibres of the Trapezius, the Pectoralis
minor, and, through the clavicle, the Subclavius. The scapula is drawn backivard
by the Rhomboids and the middle and lower fibres of the Trapezius, and forward
THE SHOULDER- JOINT
305
by the Serratus magnus and Pectoralis minor, assisted, when the arm is fixed, by
the Pectoralis major. The mobility of the scapula is very considerable, and
greatly assists the movements of the arm at the shoulder-joint. Thus, in raising
the arm from the side the Deltoid and Supraspinatus can only lift it to a right
CORACO-ACRO
LIGAME
DELTOID
MOID LIGAMENT.
BICEPS.
MIAL 1 GLS
"LaW^-
M^V§S§£
V £ .- • :.
DELTOID. SUPRA-SPINATUS.
TERES MAJOR.
SUB-
SCAPULA-
RIS.
TRICEPS.
TRICEPS.
TERES MAJOR. Circumflex vessels. • Circumflex vessels. SCAPULARIS.
FIG. 221. — Vertical sections through the shoulder-joint, the arm being vertical and horizontal. (After Henle.)
angle with the trunk, the further elevation of the limb being effected by the
Trapezius and Serratus magnus moving the scapula on the wall of the chest.
This mobility is of special importance in ankylosis of the shoulder-joint, the
movement of this bone compensating to a very great extent for the immobility
of the joint.
IV. The Shoulder-joint (Articulatio Humeri) (Figs. 219, 220, 221, 222).
The shoulder is an enarthrodial or ball-and-socket joint. The bones entering
into its formation are the large globular head of the humerus, which is received
into the shallow glenoid cavity of the scapula — an arrangement which permits of
very considerable movement, whilst the joint itself is protected against displace-
ment by the tendons which surround it and by atmospheric pressure. The liga-
ments do not maintain the joint surfaces in apposition, because when they alone
remain the humerus can be separated to a considerable extent from the glenoid
cavity ; their use, therefore, is to limit the amount of movement. Above, the joint
is protected by an arched vault, formed by the under surfaces of the coracoid and
acromion processes, and the coraco-acromial ligament. The articular surfaces
are covered by a layer of cartilage : that on the head of the humerus is thicker at
the centre than at the circumference, the reverse being the case in the glenoid
cavity. The ligaments of the shoulder are the
Capsular. Transverse humeral.
Coraco-humeral. Glenoid.1
The Capsular Ligament (capsida articularis) (Figs. 219, 220, and 222) completely
encircles the articulation, being attached, above, to the circumference of the glenoid
cavity beyond the glenoid ligament, below, to the anatomical neck of the humerus,
approaching nearer to the articular cartilage above than in the rest of its extent.
It is thicker above and below than elsewhere, and is remarkably loose and lax, and
1 The long tendon of origin of the Biceps muscle also acts as one of the ligaments of this joint. See the
observations on p. 270 on the function of the muscles passing over more than one joint. — ED. of 15th English
Edition.
20 .
306
THE ARTICULATIONS OR JOINTS
much larger and longer than is necessary to keep the bones in contact, allowing
them to be separated from each other more than an inch — an evident provision
for that extreme freedom of movement which is peculiar to this articulation. Its
superficial surface is strengthened, above, by the Supraspinatus ; below, by the
long head of the Triceps; behind, by the tendons of the Infraspinatus and Teres
minor; and in front, by the tendon of the Subscapularis. The capsular ligament
usually presents three openings: One anteriorly, below the coracoid process,
establishes a communication between the synovial membrane of the joint and a
ARTICULAR
CAPSULE
LONG HEAD OF
BICEPS MUSCLE
SUPERIOR
TRANSVERSE
LIGAMENT
SPINE OF SCAPULA „„„
(sawed off at its origin) %
FIG. 222. — Right shoulder- joint, frontal section, from behind. (Spalteholz.)
bursa beneath the tendon of the Subscapularis muscle. The second, which is
not constant, is at the posterior part, where a communication sometimes exists
between the joint and a bursal sac belonging to the Infraspinatus muscle. The
third is seen between the two tuberosities, for the passage of the long tendon
of the Biceps muscle. It transmits a sac-like prolongation of the synovial
membrane, which ends as a blind pouch opposite the surgical neck of the bone.
This synovial sac is called the vagina mucosa intertubercularis.
The Coraco-humeral Ligament (ligamentum coracohumerale) (Fig. 219) is a broad
band which strengthens the upper part of the capsular ligament. It arises from
the outer border of the coracoid process, and passes obliquely downward and out-
ward to the front of the great tuberosity of the humerus, being blended with the
tendon of the Supraspinatus muscle. This ligament is intimately united to the
capsular ligament throughout the greater part of its extent.
Supplemental Bands of the Capsular Ligament. — In addition to the coraco-
humeral ligament, the capsular ligament is strengthened by supplemental bands in
the interior of the joint. One of these bands is situated on the inner side of the
joint, and passes from the inner edge of the glenoid cavity to the lower part of the
lesser tuberosity of the humerus. This is sometimes known as Flood's ligament,
THE SHOULDER -JOINT 307
and is supposed to correspond with the ligamentum teres of the hip-joint. A
second of these bands is situated at the lower part of the joint, and passes from the
under edge of the glenoid cavity to the under part of the neck of the humerus, and
is known as Schlemm's ligament. A third, called the gleno-humeral ligament, is
situated at the upper part of the joint, and projects into its interior, so that it can
be seen only when the capsule is opened. It is attached above to the apex of the
glenoid cavity, close to the root of the coracoid process, and, passing downward
along the inner edge of the tendon of the Biceps, is attached below to the lesser
tuberosity of the humerus, where it forms the inner boundary of the upper part of
the bicipital groove. It is a thin, ribbon-like band, occasionally quite free from
the capsule.
The Transverse Humeral Ligament is a prolongation of the capsular ligament.
It is a broad band of fibrous tissue passing from the lesser to the greater tuber-
osity of the humerus, and always limited to that portion of the bone which lies
above the epiphysial line. It converts the bicipital groove into an osseo-aponeu-
rotic canal, and is the analogue of the strong process of bone which connects the
summits of the two tuberosities in the musk ox.
The Glenoid Ligament (labrum glenoidale) (Figs. 220 and 222) is a fibro-
cartilaginous rim, attached round the margin of the glenoid cavity. It is trian-
gular on section, the thickest portion being fixed to the circumference of the cavity,
the free edge being thin and sharp. It is continuous above with the long tendon
of the Biceps muscle, which bifurcates at the upper part of the cavity into two
fasciculi, and becomes continuous with the fibrous tissue of the glenoid ligament.
This ligament deepens the cavity for articulation, and protects the edges of the
bone. It is lined by the synovial membrane.
Synovial Membrane (Fig. 222). — The synovial membrane is reflected from the
margin of the glenoid cavity over the fibro-cartilaginous rim surrounding it: it is
then reflected over the internal surface of the capsular ligament, covers the lower
part and sides of the anatomical neck of the humerus as far as the cartilage cover-
ing the head of the bone. The long tendon of the Biceps muscle which passes
through the capsular ligament is enclosed in a tubular sheath of synovial membrane
(vagina mucosa intertubercularis) , which is reflected upon it at the point where it
perforates the capsule, and is continued around it as far as the level of the surgical
neck of the humerus. The tendon of the Biceps is thus enabled to traverse the
articulation, but it is not contained in the interior of the synovial cavity.
Bursae. — A large bursa exists between the joint capsule and the tendon of the
Subscapularis muscle. It is called the subscapular bursa. This sac communicates
with the shoulder-joint by means of an opening at the inner side of the capsular
ligament. The subscapular bursa is constant. Occasionally another and smaller
bursa exists beneath the tendon of the infraspinatus. It is called the infraspinatus
bursa, and communicates with the shoulder-joint by means of an opening in the outer
surface of the capsule. The subdeltoid or subacromial bursa is placed between the
under surface of the Deltoid muscle and the outer surface of the capsule. It does
not communicate with the joint. The subcutaneous acromial bursa is between the
surface and the summit of the acromion process. There is a bursa beneath
the Coraco-brachialis muscle — one beneath the teres major — and one beneath
the tendinous portion of the latissimus dorsi. There is also a bursa between the
tendon of insertion of the Pectoralis major muscle and the long head of the
biceps.
The Muscles in relation with the joint are, above, the Supraspinatus ; below, the
long head of the Triceps; in front, the Subscapularis; behind, the Infraspinatus
and Teres minor; within, the long tendon of the Biceps. The Deltoid is placed
most externally, and covers the articulation on its outer side, as well as in front
and behind.
308 THE ARTICULATIONS OR JOINTS
The Arteries supplying the joint are articular branches of the anterior and
posterior circumflex, and the suprascapular.
The Nerves are derived from the circumflex and suprascapular.
Actions. — The shoulder-joint is capable of movement in every direction, forward,
backward, abduction, adduction, circumduction, and rotation. The humerus is
drawn forward by the Pectoralis major, anterior fibres of the Deltoid, Coraco-
brachialis, and by the Biceps when the forearm is flexed ; backward, by the Latis-
simus dorsi, Teres major, posterior fibres of the Deltoid, and by the Triceps when
the forearm is extended; it is abducted (elevated) by the Deltoid and Supraspinatus;
it is adducted (depressed) by the Subscapularis, Pectoralis major, Latissimus dorsi,
and Teres major; it is rotated outward by the Infraspinatus and Teres minor;
and it is rotated inward by the Subscapularis, Latissimus dorsi, Teres major, and
Pectoralis major.
The most striking peculiarities in this joint are: 1. The large size of the head
of the humerus in comparison with the depth of the glenoid cavity, even when
supplemented by the glenoid ligament. 2. The looseness of the capsule of the
joint. 3. The intimate connection of the capsule with the muscles attached to the
head of the humerus. 4. The peculiar relation of the biceps tendon to the joint.
It is in consequence of the relative size of the two articular surfaces that the
joint enjoys such free movement in every possible direction. When these move-
ments of the arm are arrested in the shoulder-joint by the contact of the bony sur-
faces and by the tension of the corresponding fibres of the capsule, together with
that of the muscles acting as accessory ligaments, they can be carried considerably
farther by the movements of the scapula, involving, of course, motion at the
acromio- and sterno-clavicular joints. These joints are therefore to be regarded
as accessory structures to the shoulder-joint.1 The extent of these movements of
the scapula is very considerable, especially in extreme elevation of the arm, which
movement is best accomplished when the arm is thrown somewhat forward and
outward, because the margin of the head of the humerus is by no means a true
circle; its greatest diameter is from the bicipital groove downward, inward, and
backward, and the greatest elevation of the arm can be obtained by rolling its
articular surface in the direction of the measurement. The great width of the
central portion of the humeral head also allows of very free horizontal movement
when the arm is raised to a right angle, in which movement the arch formed by the
acromion, the coracoid process, and the coraco-acromial ligament constitutes a
sort of supplemental articular cavity for the head of the bone.
The looseness of the capsule is so great that the arm will fall about an inch
from the scapula when the muscles are dissected from the capsular ligament and
an opening made in it to remove the atmospheric pressure. The movements of
the joint, therefore, are not regulated by the capsule so much as by the surrounding
muscles and by the pressure of the atmosphere — an arrangement which "renders
the movements of the joint much more easy than they would otherwise have been,
and permits a swinging, pendulum-like vibration of the limb when the muscles
are at rest" (Humphry). The fact, also, that in all ordinary positions of the joint
the capsule is not put on the stretch enables the arm to move freely in all direc-
tions. Extreme movements are checked by the tension of appropriate portions of
the capsule, as well as by the interlocking of the bones. Thus it is said that
" abduction is checked by the contact of the great tuberosity with the upper edge of
the glenoid cavity, adduction by the tension of the coraco-humeral ligament"
(Beaunis et Bouchard). Cleland2 maintains that the limitations of movement at
the shoulder-joint are due to the structure of the joint itself, the glenoid ligament
fitting, in different positions of the elevated arm, into the anatomical neck of the
humerus.
1 See p. 303. 2 Journal of Anatomy and Physiology, 1884, vol. xviii.
THE SHOULDER -JOINT 399
Cathcart1 has pointed out that in abducting the arm and raising it above the
head, the scapula rotates throughout the whole movement with the exception of
a short space at the beginning and at the end; that the humerus moves on the
scapula not only from the hanging to the horizontal position, but also in passing
upward as it approaches the vertical above; that the clavicle moves not only
during the second half of the movement but in the first as well, though to a less
extent — i. e., the scapula and clavicle are concerned in the first stage as well as in
the second; and that the humerus is partly involved in the second as well as
chiefly in the first.
The intimate union of the tendons of the four short muscles with the capsule
converts these muscles into elastic and spontaneously acting ligaments of the joint,
and it is regarded as being also intended to prevent the folds into which all portions
of the capsule would alternately fall in the varying positions of the joint from being
driven between the bones by the pressure of the atmosphere.
The peculiar relations of the Biceps tendon to the shoulder-joint appear to sub-
serve various purposes. In the first place, by its connection with both the shoulder
and elbow the muscle harmonizes the action of the two joints, and acts as an
elastic ligament in all positions, in the manner previously adverted to.2 Next, it
strengthens the upper part of the articular cavity, and prevents the head of the
humerus from being pressed up against the acromion process, when the Deltoid
contracts, instead of forming the centre of motion in the glenoid cavity. By its
passage along the bicipital groove it assists in rendering the head of the humerus
steady in the various movements of the arm. When the arm is raised from the
side it assists the Supra- and Infraspinatus in rotating the head of the humerus in
the glenoid cavity. It also holds the head of the bone firmly in contact with the
glenoid cavity, and prevents its slipping over its lower edge, or being displaced by
the action of the Latissimus dorsi and Pectoralis major, as in climbing and many
other movements.
Surface Form. — The direction and position of the shoulder-joint may be indicated by a line
drawn from the middle of the coraco-acromial ligament, in a curved direction, with its con-
vexity inward, to the innermost part of that portion of the head of the humerus which can be
felt in the axilla when the arm is forcibly abducted from the side. When the arm hangs by the
side, not more than one-third of the head of the bone is in contact with the glenoid cavity, and
three-quarters of its circumference is in front of a vertical line drawn from the anterior border
of the acromion process.
Surgical Anatomy. — Owing to the construction of the shoulder-joint and the freedom of
movement which it enjoys, as well as in consequence of its exposed situation, it is more frequently
dislocated than any other joint in the body. Dislocations of the shoulder contribute about forty
per cent, of the cases in tables of dislocations. Dislocation occurs when the arm is thrown into
extreme abduction, and when, therefore, the head of the humerus presses against the lower and
front part of the capsule, which is the thinnest and least supported part of the ligament. The
rent in the capsule almost invariably takes place in this situation, between the tendon of the Sub-
scapularis and the Triceps, and through it the head of the bone escapes, so that the dislocation
in most instances is primarily subglenoid. The head of the bone does not usually remain in this
situation, but generally assumes some other position, which varies according to the direction and
amount of force producing the dislocation and the relative strength of the muscles in front and
behind the joint. In consequence of the muscles at the back being weaker than those in front,
and especially on account of the long head of the Triceps preventing the bone passing backward,
dislocation forward is much more common than backward. The most frequent position which
the head of the humerus ultimately assumes is on the front of the neck of the scapula, beneath
the coracoid process, and hence named subcoracoid dislocation. Occasionally, in consequence
probably of a greater amount of force being brought to bear on the limb, the head is driven
farther inward, and rests on the upper part of the front of the chest, beneath the clavicle (sub-
clavicular). If the head of the bone passes under the Subscapularis muscle and also under
the Teres major or the lower border of the Pectoralis major, the arm remains abducted, or even
with the elbow raised above the head (hixatio erecta). Sometimes the humerus remains in the
position in which it was primarily displaced, resting on the axillary border of the scapula (sub-
1 Journal of Anatomy and Physiology, 1884, vol. xviii. 2 See p. 270.
310 THE ARTICULATIONS OR JOINTS
glenoid), and rarely it passes backward and remains in the infraspinatous fossa beneath the
spine (subspinous). If dislocation frequently recurs the condition may be amended in some
cases by exposing the capsule and putting tucks in it by means of sutures.
An old unreduced dislocation is sometimes treated by incising the soft parts and returning
the head of the humerus into the glenoid cavity. In other cases the head of the humerus is
excised. Dislocation of the long tendon of the Biceps muscle from the bicipital groove is a rare
accident. When it occurs the arm is rigid in abduction, but the head of the humerus is found
to be in the glenoid cavity. It is reduced by flexion of the elbow and rotation of the arm.
Rupture of the long tendon of the biceps is more common than dislocation of the tendon.
After this injury the belly of the muscle is relaxed and is nearer than normal to the elbow;
flexion of the forearm is much weakened, and is weaker in supination than it is in pronation.
The head of the humerus passes forward and inward, and the condition is often mistaken for
dislocation of the bone.
If we desire to aspirate the shoulder-joint, place the arm against the side, flex the forearm at
a right angle to the arm, carry the forearm across the front of the chest, and enter the trocar
below the acromion (De Vos).
The shoulder-joint is sometimes the seat of all those inflammatory affections, both acute and
chronic, which attack joints, though perhaps it suffers less frequently than some other joints of
equal size and importance. Acute synovitis may result from injury, rheumatism, or pyaemia, or
may follow secondarily on the so-called acute epiphysitis of infants. It is attended with effusion
into the joint, and when this occurs the capsule is evenly distended and the contour of the joint
rounded. Special projections may occur at the site of the openings in the capsular ligament.
Thus a swelling may appear just in front of the joint, internal to the lesser tuberosity, from effu-
sion into the bursa beneath the Subscapularis muscle; or, again, a swelling which is sometimes
bilobed may be seen in the interval between the Deltoid and Pectoralis major muscles, from effu-
sion into the diverticulum, which runs down the bicipital groove with the tendon of the biceps.
The effusion into the synovial membrane can be best ascertained by examination from the axilla,
where a soft, elastic, fluctuating swelling can usually be felt. The bursa beneath the deltoid is
sometimes ruptured by violence, and sometimes inflames, suppurates, or becomes tuberculous.
Tuberculous arthritis not unfrequently attacks the shoulder-joint, and may lead to total
destruction of the articulation, when ankylosis may result or long-protracted suppuration may
necessitate excision. This joint is also one of those which is most liable to be the seat of osteo-
arthritis, and may also be affected in gout and rheumatism; or in locomotor ataxia, when it
occasionally becomes the seat of Charcot's disease.
Excision of the shoulder-joint may be required in cases of arthritis (especially the tuber-
culous form) which have gone on to destruction of the articulation; in compound dislocations and
fractures, particularly those arising from gunshot injuries, in which there has been extensive
injury to the head of the bone; in some cases of old unreduced dislocation, where there is much
pain; and possibly in some few cases of growth connected with the upper end of the bone. The
operation is best performed by making an incision from the middle of the coraco-acromial liga-
ment down the arm for about three inches: this will expose the bicipital groove and the tendon
of the Biceps, which may be either divided or hooked out of the way, according as to whether it
is implicated in the disease or not. The capsule is then freely opened, and the muscles attached
to the greater and lesser tuberosities of the humerus divided. The head of the bone can then
be thrust out of the wound and sawn off, or divided with a narrow saw in situ and subsequently
removed. The section should be made, if possible, just below the articular surface, so as to
leave the bone as long as possible. The glenoid cavity must then be examined, and gouged
if carious.
V. The Elbow-joint (Articulatio Cubiti) (Figs. 223, 224, 225, 226).
The elbow is a ginglymus or hinge-joint. The bones entering into its forma-
tion are the trochlea of the humerus, which is received into the greater sigmoid
cavity of the ulna (articulatio humeroulnaris) , and admits of the movements
peculiar to this joint — viz., flexion and extension; whilst the capitellum or radial
head of the humerus articulates with the cup-shaped depression on the head of
the radius (articulatio humeroradialis) ; the circumference of the head of the
radius articulates with the lesser sigmoid cavity of the ulna (articulatio radio-
ulnaris proximalis) , allowing of the movement of rotation of the radius on the
ulna, the chief action of the superior radio-ulnar articulation. The articular
surfaces are covered with a thin layer of cartilage, and connected together by a
capsular ligament (capsula articularis) (Fig. 225) of unequal thickness, being
especially thickened on its two sides and, to a less extent, in front and behind.
THE ELBOW -JOINT
311
These thickened portions are usually described as distinct ligaments under the
following names:
Anterior. Internal Lateral
Posterior. External Lateral.
The orbicular ligament of the upper radio-ulnar articulation must also be
reckoned among the ligaments of the elbow.
The Anterior Ligament (Fig. 223) is a broad and thin fibrous layer which covers
the anterior surface of the joint. It is attached to the front of the internal condyle
and to the front of the humerus immediately above the coronoid and radial fossae;
below, to the anterior surface of the coronoid process of the ulna and to the
orbicular ligament, being continuous on each side with the lateral ligaments. Its
FIG. 223. — Left elbow-joint, showing anterior
and internal ligaments.
FIG. 224. — Left elbow-joint, showing posterior
and external ligaments.
superficial fibres pass obliquely from the inner condyle of the humerus outward to
the orbicular ligament. The middle fibres, vertical in direction, pass from the
upper part of the coronoid depression and become partly blended with the pre-
ceding, but are mainly inserted into the anterior surface of the coronoid process.
The deep or transverse set intersects these at right angles. This ligament is in
relation, in front, with the Brachialis anticus muscle, except at its outermost
part; behind, it is in relation with the synovial membrane.
The Posterior Ligament (Fig. 224) is a thin and loose membranous fold, attached,
above, to the lower end of the humerus. above and at the sides of the olecranon
312
THE ARTICULATIONS OR JOINTS
CORONOID
PROCESS
OLECRANON
FOSSA
ARTICULAR
CAPSULE
fossa; below, to the groove on the upper and outer surfaces of the olecranon. The
superficial or transverse fibres pass between the adjacent margins of the olecranon
fossa. The deeper portion consists of vertical fibres, some of which, thin and
weak, pass from the upper part of the olecranon fossa to the margin of the olec-
ranon ; others, thicker and stronger, pass from the back of the capitellum of the
humeras to the posterior border of the lesser sigmoid cavity of the ulna. This
ligament is in relation, behind, with the tendon of the Triceps muscle and the
Anconeus muscle; in front, with the synovial membrane.
The Internal Lateral Ligament (ligamentum collaterale ulnare) (Fig. 223) is a
thick triangular band consisting of two portions, an anterior and posterior, united
by a thinner intermediate portion. The anterior portion, directed obliquely forward,
is attached, above, by its apex,
to the front part of the in-
ternal condyle of the humerus ;
and, below, by its broad base,
to the inner margin of the
coronoid process. The poste-
rior portion, also of triangular
form, is attached, above, by
its apex, to the lower and back
part of the internal condyle;
below, to the inner margin of
the olecranon. Between these
two bands a few intermediate
fibres descend from the inter-
nal condyle to blend with a
transverse band of ligament-
ous tissue which bridges
across the notch between the
olecranon and coronoid pro-
cesses. This ligament is in
relation, internally, with the
Triceps and Flexor carpi
ulnaris muscles and the ulnar
nerve, and gives origin to part
of the Flexor sublimis digi-
torum muscle.
The External Lateral Liga-
ment (ligamentum collaterale
radiale) (Fig. 224) is a short
and narrow fibrous band less
distinct than the internal, at-
tached, above, to a depression
below the external condyle of
the humerus; below, to the
orbicular ligament, some of its
most posterior fibres passing over that ligament, to be inserted into the outer
margin of the ulna. This ligament is intimately blended with the tendon of
origin of the Supinator brevis muscle.
Synovial Membrane (Fig. 225) . — The 'synovial membrane is very extensive. It
covers the margin of the articular surface of the humerus, and lines the coronoid
and olecranon fossa on that bone; from these points it is reflected over the anterior,
posterior, and lateral ligaments, and forms a pouch (recessus sacciformis) between
the lesser sigmoid cavity, the internal surface of the orbicular ligament, and the
EPIPHYSEAL
JUNCTION
EPIPHYSEAL
JUNCTION
FIG. 225. — Right elbow-joint, cut through at right angles to the
axis of the trochlea humeri, from the ulnar side. (Spalteholz.)
THE ELBOW- JOINT
313
circumference of the head of the radius. Projecting into the cavity is a crescentic
fold of synovial membrane, between the radius and ulna, suggesting the division of
the joint into two : one the humero-radial, the other the humero-ulnar.
Between the capsular ligament and the synovial membrane are three masses
of fat : one, the largest, above the olecranon fossa, which is pressed into the fossa by
the Triceps during flexion; a second, over the coronoid fossa; and a third, over
the radial fossa. The two last-named pads are pressed into their respective fossre
during extension.
The muscles (Fig. 226) in relation with the joint are, in front, the Brachialis
anticus; behind, the Triceps and Anconeus; externally, the Supinator brevis and
the common tendon of origin of the Ex-
tensor muscles ; internally, the common
tendon of origin of the Flexor muscles, and
the Flexor carpi ulnaris, with the ulnar
nerve.
The arteries supplying the joint are de-
rived from the anastomosis between the
superior profunda, inferior profunda, and
anastomotica magna, bi inches of the
brachial, with the anterior, posterior, and
interosseous recurrent branches of the
ulnar and the recurrent branch of the
radial. These vessels form a complete
chain of inosculation around the joint.
The nerves are derived from the ulnar
as it passes between the internal condyle
and the olecranon ; a filament from the
musculo-cutaneous (Rudinger), and two
filaments from the median (Macalister).
Bur sae. — The olecranon bursa (bursa sub-
cutaneous olecrani) is placed between the
olecranon process and the cutaneous sur-
face. A bursa exists between the tendon
of the Biceps and the tubercle of the
radius (bursa bicipitoradialis) — another
between the Triceps tendon and the olec-
ranon process (bursa subtendinea olecrani)
— another between the cutaneous surface
and the external condyle (bursa subcutanea epicondyli humeri lateralis) — another
between the cutaneous surface and the internal condyle (bursa subcutanea
epicondyli humeri medialis — another within the Triceps tendon at its insertion on
the olecranon (bursa intratendinea olecrani).
Actions. — The elbow-joint comprises three different portions — viz., the joint
between the ulna and humerus, that between the head .of the radius and the
humerus, and the superior radio-ulnar articulation, described below. All these
articular surfaces are invested by a common synovial membrane, and the move-
ments of the whole joint should be studied together. The combination of the
movements of flexion and extension of the forearm with those of pronation and
supination of the hand, which is ensured by the two being performed at the
same joint, is essential to the accuracy of the various minute movements of the
hand.
The portion of the joint between the ulna and humerus is a simple hinge-
joint, and allows of movements of flexion and extension only. Owing to the
obliquity of the trochlear surface of the humerus, this movement does not take
FIG. 226. — Sagittal section of the right elbow-
joint, taken somewhat obliquely and seen from the
radial aspect. (After Braune.)
314 THE ARTICULATIONS OR JOINTS
place in a straight line. When the forearm is extended and supinated the axis
of the arm is not in the same line as the axis of the forearm, but the axis of the arm
forms an angle with the axis of the forearm, and the hand, with the forearm, is
directed outward. During flexion, on the other hand, the forearm and the hand
tend to approach the middle line of the body, and thus enable the hand to be easily
carried to the face. The shape of the articular surface of the humerus, with its
prominences and depressions accurately adapted to the opposing surface of the
olecranon, prevents any lateral movement. Flexion is produced by the action
of the Biceps and Brachialis anticus, assisted by the muscles arising from the in-
ternal condyle of the humerus and the Supinator longus; extension, by the Triceps
and Anconeus, assisted by the extensors of the wrist and by the Extensor communis
digitorum and Extensor minimi digiti.
The joint between the head of the radius and the capitellum or radial head of the
humerus is an arthrodial joint. The bony surfaces would of themselves constitute
an enarthrosis, and allow of movement in all directions were it not for the orbicular
ligament by which the head of the radius is bound down firmly to the lesser
sigmoid cavity of the ulna, and which prevents any separation of the two bones
laterally. It is to the same ligament that the head of the radius owes its security
from dislocation, which would otherwise constantly occur as a consequence of the
shallowness of the cup-like surface on the head of the radius. In fact, but for
this ligament the tendon of the biceps would be liable to pull the head of the
radius out of the joint.1 In complete extension the head of the radius glides so
far back on the outer condyle that its edge is plainly felt at the back of the articu-
lation. Flexion and extension of the elbow-joint are limited by the tension of
the structures on the front and back of the joint, the limitation of flexion being
also aided by the soft structures of the arm and forearm coming in contact.
In combination with any position of flexion or extension the head of the radius
can be rotated in the upper radio-ulnar joint, carrying the hand with it. The
hand is directly articulated to the lower surface of the radius only, and the concave
or sigmoid surface on the lower end of the radius travels round the lower end of
the ulna. The latter bone is excluded from the wrist-joint (as will be seen in
the sequel) by the interarticular fibro-cartilage. Thus, rotation of the head of the
radius round an axis which passes through the centre of the radial head of the
humerus imparts circular movement to the hand through a very considerable
arc.
Surface Form. — If the forearm be slightly flexed on the arm, a curved crease or fold with
its convexity downward may be seen running across the front of the elbow, extending from one
condyle to the other. The centre of this fold is some slight distance above the line of the joint.
The position of the radio-humeral portion of the joint can be at once ascertained by feeling for a
slight groove or depression between the head of the radius and the capitellum of the humerus at
the back of the articulation.
Surgical Anatomy. — From the great breadth of the joint, and the manner in which the
articular surfaces are interlocked, and also on account of the strong lateral ligaments and
the support which the joint derives from the mass of muscles attached to each condyle of the
humerus, lateral displacement of the bones is very uncommon, whereas antero-posterior disloca-
tion, on account of the shortness of the antero-posterior diameter, the weakness of the anterior
and posterior ligaments, and the want of support of muscles, much more frequently takes place,
dislocation backward taking place when the forearm is in a position of extension, and forward
when in a position of flexion. For, in the former position, that of extension, the coronoid process
is not interlocked into the coronoid fossa, and loses its grip to a certain extent, whereas the
olecranon process is in the olecranon fossa, and entirely prevents displacement forward. On
the other hand, during flexion, the coronoid process is in the coronoid fossa, and prevents dis-
location backward, while the olecranon loses its grip and is not so efficient, as during extension,
in preventing a forward displacement. When lateral dislocation does take place, it is generally
incomplete.
1 Humphry, op cit., p. 419.
RADIO- ULNAR ARTICULATION 315
Dislocation of the elbow-joint is of common occurrence in children, far more common than
dislocation of any other articulation, for, as a rule, fracture of a bone more frequently takes
place, under the application of any severe violence, in young persons than dislocation. In
lesions of this joint there is often very great difficulty in ascertaining the exact nature of the
injury. Sprain of the elbow is a very common injury in childhood. Injury to the radio-
humeral joint is frequently produced by lifting a child by the hand, as in swinging it over a
gutter. The supinator brevis, which under normal circumstances would retain the head of the
radius against the capitellum of the humerus, is unable to do so, the radio-humeral articulation
receives the force and the orbicular ligament undergoes upward displacement, is caught
between the head of the radius and the capitellum and jams the joint.1 This injury is often
called subluxation of the head of the radius.
The elbow-joint is occasionally the seat of acute synovitis. The synovial membrane then
becomes distended with fluid, the bulging showing itself principally around the olecranon process;
that is to say, on its inner and outer sides and above, in consequence of the laxness of the poste-
rior ligament. Occasionally a well-marked, triangular projection may be seen on the outer
side of the olecranon, from bulging of the synovial membrane beneath the Anconeus muscle.
Again, there is often some swelling just above the head of the radius, in the line of the radio-
humeral joint. There is generally not much swelling at the front of the joint, though sometimes
deep-seated fulness beneath the Brachialis anticus may be noted. When suppuration occurs the
abscess usually points at one or other border of the Triceps muscle; occasionally the pus dis-
charges itself in front, near the insertion of the Brachialis anticus muscle. Chronic synovitis,
usually of tuberculous origin, is of common occurrence in the elbow-joint: under these circum-
stances the forearm tends to assume the position of semi-flexion, which is that of greatest ease
and relaxation of ligaments. It should be borne in mind that should ankylosis occur in this or
the extended position, the limb will not be nearly so useful as if it becomes ankylosed in a position
of rather less than a right angle. Loose cartilages are sometimes met with in the elbow-joint, not
so commonly, however, as in the knee; nor do they, as a rule, giVe rise to such urgent symptoms.
They rarely require operative interference. The elbow-joint is also sometimes affected with
osteo-arthritis, but this affection is less common in this articulation than in some other of the
larger joints. Bursitis about the elbow is not uncommon. Enlargement of the subcutaneous
bursa over the olecranon is known as miners' elbow. Enlargement of any one of the bursse
may occur.
Excision of the elbow is principally required for one of three conditions — viz., tuberculous
arthritis, injury and its results, and ankylosis in a position which greatly impairs the .useful-
ness of the limb; but may be necessary for some other rarer conditions, such as disorganizing
arthritis after pyamia, unreduced dislocation, and osteo-arthritis. The results of the opera-
tion are, as a rule, more favorable than those of excision of any other joint, and it is one,
therefore, that the surgeon should never hesitate to perform, especially in the first three of
the conditions mentioned above. The operation is best performed by a single vertical incision
down the back of the joint, a transverse incision, over the outer condyle, being added if the
parts are much thickened and fixed. A straight incision is made about four inches long, the
mid-point of which is on a level with and a little to the inner side of the tip of the olecra-
non. This incision is made down to the bone, through the substance of the Triceps muscle.
The operator with the point of his knife, and guarding the soft parts with his thumb-nail,
separates them from the bone. In doing this there are two structures which he should
carefully avoid: the ulnar nerve, which lies parallel to his incision, but a little internal, as it
courses down between the internal condyle and the olecranon process, and the prolongation of
the Triceps into the deep fascia of the forearm over the Anconeus muscle. Having cleared the
bones and divided the lateral and posterior ligaments, the forearm is strongly flexed and the
ends of the bone turned out and sawn off. The section of the humerus should be through
the base of the condyles, that of the ulna and radius should be just below the level of the lesser
sigmoid cavity of the ulna and the neck of the radius. In this operation the object is to obtain
such fibrous union as shall allow free motion of the bones of the forearm; and, therefore, passive
motion must be commenced early, that is to say, about the tenth day.
VI. Radio-ulnar Articulation (Articulatio Radioulnaris).
The articulation of the radius with the ulna is effected by ligaments which
connect together both extremities as well as the shafts of these bones. It may,
consequently, be subdivided into three articulations: (1) the superior radio-ulnar,
which is a portion of the elbow-joint; (2) the middle radio-ulnar; and (3) the infe-
rior radio-ulnar articulations.
1 Mr. Jonathan Hutchinson, Jr., in Annals of Surgery, August, 1885.
316 THE ARTICULATIONS OR JOINTS
1. SUPERIOR OR PROXIMAL RADIO-ULNAR ARTICULATION (ARTICULATIO
RADIOULNARIS PROXIMALIS) .
This articulation is a trochoid or pivot-joint. The bones entering into its forma-
tion are the inner side of the circumference of the head of the radius rotating within
the lesser sigmoid cavity of the ulna. Its only ligament is the annular or orbicular.
The Orbicular or Annular Ligament (ligamentum annulare radii) (Figs. 223, 224,
and 227) is a strong, flat band of ligamentous fibres which surrounds the head of
the radius and retains it in firm connection with the lesser sigmoid cavity of the
ulna. It forms about four-fifths of an osseo-fibrous ring, attached by each end to
the extremities of the lesser sigmoid cavity, and is smaller at the lower part of its
circumference than above, by which means the head of the radius is more securely
held in its position. Its outer surface is strengthened by the external lateral
ligament of the elbow, and affords origin to part of the Supinator brevis muscle.
Its inner surface is smooth, and lined by synovial membrane. The synovial
membrane is continuous with that which lines the elbow-joint.
Actions. — The movement which takes place in this articulation is limited to
rotation of the head of the radius within the orbicular ligament, and upon the
lesser sigmoid cavity of the ulna, rotation forward being called pronation; rotation
backward, supination. Supination is performed by the Biceps and Supinator
brevis, assisted to a slight extent by the Extensor muscles of the thumb and,
in certain positions, by the Supinator longus. Pronation is performed by the
Pronator radii teres and the Pronator quadratus, assisted, in some positions, by
the Supinator longus.
Surface Form. — The position of the superior radio-ulnar joint is marked on the surface of
the body by the little dimple on the back of the elbow which indicates the position of the head
of the radius.
Surgical Anatomy. — Dislocation of the head of the radius alone is not an uncommon acci-
dent, and occurs most frequently in young persons from falls on the hand when the forearm is
extended and supinated, the head of the bone being displaced forward. It is attended by rup-
ture of the orbicular ligament. Occasionally a peculiar injury, which is supposed to be a sub-
luxation, occurs in young children in lifting them from the ground by the hand or forearm. It
is believed that the head of the radius is displaced downward or the orbicular ligament upward,
and the upper border of the ligament becomes folded over the head of the radius, between it and
the capitellum of the humerus.
2. MIDDLE RADIO-ULNAR LIGAMENTS.
The interval between the shafts of the radius and ulna is occupied by two
ligaments.
Oblique. Interosseous.
The Oblique or Round Ligament (chorda obliqua) (Figs. 223 and 225) is a small,
flattened fibrous band which extends obliquely downward and outward from the
tubercle of the ulna at the base of the cororioid process to the radius a little below
the bicipital tuberosity. Its fibres run in the opposite direction to those of the
interosseous ligament, and it appears to be placed as a substitute for it in the
upper part of the interosseous interval. This ligament is sometimes wanting.
The Interosseous Membrane (membrana interossea antibrachii) (Fig. 227) is a
broad and thin plane of fibrous tissue descending obliquely downward and inward,
from the interosseous ridge on the radius to that on the ulna. It is deficient above,
commencing about an inch beneath the tubercle of the radius; is broader in the
middle than at either extremity; and presents an oval aperture just above its
lower margin for the passage of the anterior interosseous vessels to the back of
the forearm. This ligament serves to connect the bones and to increase the
extent of surface for the attachment of the deep muscles. Between its upper
RADIO- ULNAR ARTICULATION
317
ANNULAR LIGAMENT
OF RADIUS
border and the oblique ligament an interval exists through which the posterior
interosseous vessels pass to the dorsum of the forearm. Two or three
fibrous bands are occasionally found
on the posterior surface of this mem-
brane which descend obliquely from
the ulna toward the radius, and which
have consequently a direction contrary
to that of the other fibres. It is in
relation, in front, by its upper three-
fourths with the Flexor longus pollicis
on the outer side, and with the Flexor
profundus digitorum on the inner, lying
upon the interval between which are
the anterior interosseous vessels and
nerve ; by its lower fourth, with the
Pronator quadratus; behind, with the
Supinator brevis, Extensor ossis meta-
carpi pollicis, Extensor brevis pollicis,
Extensor longus pollicis, Extensor in-
dicis; and, near the wrist, with the
anterior interosseous artery and poste-
rior interosseous nerve.
3. INFERIOR OR DISTAL RADIO-ULNAR
ARTICULATION (ARTICULATIO RA-
DIOULNARIS DlSTALIS).
TENDON OF
BICEPS MUSCLE
(cut through)
OBLIQUE
LIGAMENT"
INTEROSSEOUS
MEMBRANE'
This is a pivot-joint, formed by the
sigmoid cavity at the inner side of the
lower end of the radius receiving the
head of the ulna. The articular sur-
faces are covered by a thin layer of
cartilage, and connected together by a
capsule (capsula articularis) , portions
of which are usually described as dis-
tinct ligaments. The ligaments of the
articulation are:
Anterior Radio-ulnar.
Posterior Radio-ulnar.
Triangular Interarticular Fibro-
cartilage.
The Anterior Radio-ulnar Ligament
(Fig. 228) is a narrow band of fibres
extending from the anterior margin of
the sigmoid cavity of the radius to the
anterior surface of the head of the ulna.
The Posterior Radio-ulnar Ligament
(Fig. 229) extends between similar
points on the posterior surface of the
articulation.
The Triangular Interarticular Fibro-cartilage (discus articularis] (Figs. 227 and 231)
is triangular in shape, and is placed transversely beneath the head of the ulna,
binding the lower end of this bone and the radius firmly together. Its periphery
STYLO ID
.PROCESS
OF ULNA
[TRIANGULAR
INTCRARTICULAR
FIBROCARTILAGE
_STYLOID PROCESS
OF RADIUS
FIG. 227. — Bones of the right forearm, with ligaments
from the volar surface. (Spalteholz.)
318
THE ARTICULATIONS OR JOINTS
is thicker than its centre, which is thin and occasionally perforated. It is attached
by its apex to a depression which separates the styloid process of the ulna from
the head of that bone; and by its base, which is thin, to the prominent edge of
Wrist-joint.
Inferior radio-ulnar
articulation.
Carpal articulations.
Carpo-metacarpal
articulations.
FIG. 228.— Ligaments of wrist and hand. Anterior view.
the radius, which separates the sigmoid cavity from the carpal articulating sur-
face. Its margins are united to the ligaments of the wrist-joint. Its upper sur-
face, smooth and concave, articulates with the head of the ulna, forming an
Inferior radio-ulnar
articulation.
Wrist-joint.
Carpal articulations.
Carpo-metacarpal
articulations
FIG. 229. — Ligaments of wrist and hand. Posterior view.
arthrodial joint; its under surface, also concave and smooth, forms part of the
wrist-joint and articulates with the cuneiform and inner part of the semilunar
bone. Both surfaces are lined by a synovial membrane — the upper surface, by
RADIO -CARPAL OR WRIST -JOINT
319
one peculiar to the radio-ulnar articulation; the under surface, by the synovial
membrane of the wrist.
Synovial Membrane. — The synovial membrane (Fig. 231) of this articulation
has been called, from its extreme looseness, the membrana sacciformis. It projects
horizontally inward between the head of the ulna and the interarticular fibro-
cartilage, and upward between the radius and the ulna, forming a very loose
cul-de-sac (recessus sacciformis). The quantity
of synovia which it contains is usually consider-
able. The inferior radio-ulnar joint does not
communicate with the wrist-joint.
Actions. — The movement in the inferior radio-
ulnar articulation is just the reverse of that in
the superior radio-ulnar joint. It consists of a
movement of rotation of the lower end of the
radius round an axis which corresponds to the
centre of the head of the ulna. When the radius
rotates forward, pronation of the forearm and
hand is the result; and when backward, supina-
tion. It will thus be seen that in pronation and
supination of the forearm and hand the radius
describes a segment of a cone, the axis of which
extends from the centre of the head of the radius
to the middle of the head of the ulna. In this
movement, however, the ulna is not quite sta-
tionary, but rotates a little in the opposite direc-
tion. So that it also describes the segment of a
cone, though of smaller size than that described
by the radius. The movement which causes this
alteration in the position of the head of the ulna
takes place principally at the shoulder-joint by a
rotation of the humerus, but possibly also to a
slight extent at the elbow-joint.1
Surface Form. — The position of the inferior radio-
ulnar joint may be ascertained by feeling for a slight
groove at the back of the wrist, between the prominent
head of the ulna and the lower end of the radius, when
the forearm is in a state of almost complete pronation.
VII. Radio-carpal or Wrist-joint (Articulatio
Radiocarpea) (Figs. 228, 229, 231).
The wrist is a condyloid articulation. The
parts entering into its formation are the lower ^ 230 _Longitudinal section of the
end Of the radius and Under Surface Of the right forearm, hand, and third finger,
.. , . , , , viewed from the ulnar aspect. (Alter
interarticular fibro-cartilage, which lorm together Braune.)
the receiving cavity, and the scaphoid, semilunar,
and the cuneiform bones, which form the condyle. The articular surface of the
radius and the under surface of the interarticular fibro-cartilage are the receiving
cavity, forming together a transversely elliptical concave surface. The articular
surfaces of the scaphoid, semilunar, and cuneiform bones form together a smooth,
convex surface, the condyle, which is received into the concavity above men-
tioned. All the bony surfaces of the articulation are covered with cartilage, and
1 See Journal of Anatomy and Physiology, vol. xix., parts ii., iii., and iv.
THE ARTICULATIONS OR JOINTS
connected together by a loose capsule (capsula articularis) , which is divided into
the following ligaments :
External Lateral. Anterior.
Internal Lateral. Posterior.
The External Lateral Ligament ( ligamentum collaterale carpi radiate) (Fig. 228)
extends from the summit of the styloid process of the radius to the outer side of
the scaphoid, some of its fibres being prolonged to the trapezium and annular
ligament.
The Internal Lateral Ligament (ligamentum collaterale carpi ulnare) (Fig. 228)
is a rounded cord, attached, above, to the extremity of the styloid process of the
ulna, and dividing below into two fasciculi, which are attached, one to the inner
side of the cuneiform bone, the other to the pisiform bone and annular ligament.
The Anterior or Volar Ligament (ligamentum radiocarpeum volare) (Fig. 228)
is a broad, membranous band, attached, above, to the anterior margin of the
lower end of the radius, its styloid process, and the ulna : its fibres pass downward
and inward to be inserted i^to the palmar surface of the scaphoid, semilunar,
and cuneiform bones, some of the fibres being continued to the os magnum. In
addition to this broad membrane there is a distinct rounded fasciculus, superficial
to the rest, which passes from the base of the styloid process of the ulna to
the semilunar and cuneiform bones. This ligament is perforated by numerous
apertures for the passage of vessels, and is in relation, in front, with the tendons
of the Flexor profundus digitorum and Flexor longus pollicis; behind, with the
synovial membrane of the wrist-joint.
The Posterior or Dorsal Ligament (ligamentum radiocarpeum dorsale) (Fig. 229),
less thick and strong than the anterior, is attached, above, to the posterior border
of the lower end of the radius ; its fibres pass obliquely downward and inward, to
be attached to the dorsal surface of the scaphoid, semilunar, and cuneiform bones,
being continuous with those of the dorsal carpal ligaments. This ligament is in
relation, behind, with the extensor tendons of the fingers; in front, with the syno-
vial membrane of the wrist.
Synovial Membrane. — The synovial membrane (Fig. 231) lines the inner sur-
face of the ligaments above described, extending from the lower end of the radius
and interarticular fibro-cartilage above to the articular surfaces of the carpal bones
below. It is loose and lax, and presents numerous folds, especially behind.
Relations. — The wrist-joint is covered in front by the flexor and behind by the
extensor tendons (Fig. 230) ; it is also in relation with the radial and ulnar
arteries.
The arteries supplying the joint are the anterior and posterior carpal branches
of the radial and ulnar, the anterior and posterior interosseous, and some ascend-
ing branches from the deep palmar arch.
The nerves are derived from the ulnar and posterior interosseous.
Actions. — The movements permitted in this joint are flexion, extension, abduc-
tion, adduction, and circumduction. Its actions will be further studied with those
of the carpus, with which they are combined.
Surface Form. — The line of the radio-carpal joint is on a level with the apex of the styloid
process of the ulna.
Surgical Anatomy. — The wrist-joint is rarely dislocated, its strength depending mainly
upon the numerous strong tendons which surround the articulation. Its security is further pro-
vided for by the number of small bones of which the carpus is made up, and which are united
by very strong ligaments. The slight movement which takes place between the several bones
serves to break the jars that result from falls or blows on the hand. Dislocation backward,
which is the more common dislocation, simulates to a considerable extent Colles's fracture of the
radius, and is liable to be mistaken for it. The diagnosis can be easily made out by observing
the relative position of the styloid processes of the radius and the ulna. In the natural condition
ARTICULATIONS OF THE CARPUS 321
the styloid process of the radius is on a lower level — i. e., nearer the ground — when the arm hangs
by the side, than that of the ulna, and the same would be the case in dislocation. In Collcs's
fracture, on the other hand, the styloid process of the radius is on the same or even a higher
level than that of the ulna.
The wrist-joint is occasionally the seat of acute synovitis, the result of traumatism or arising
in the rheumatic or pysemic state. When the synovial sac is distended with fluid, the swelling
is greatest on the dorsal aspect of the wrist, showing a general fulness, with some bulging between
the tendons. The inflammation is prone to extend to the intercarpal joints and to attack also
the sheaths of the tendons in the neighborhood. Chronic inflammation of the wrist is generally
tuberculous, and often leads to similar disease in the synovial sheaths of adjacent tendons and of
the intercarpal joints. The disease, therefore, when progressive, often leads to necrosis of the
carpal bones, and the result is often unsatisfactory.
VIII. Articulations of the Carpus (Articulatio Intercarpea)
(Figs. 228, 229, 231).
These articulations may -be subdivided into three sets :
1. The Articulations of the First Row of Carpal Bones.
2. The Articulations of .the Second Row of Carpal Bones.
3. The Articulations of the Two Rows with each other.
1. ARTICULATIONS OF THE FIRST Row OF CARPAL BONES.
These are arthrodial joints. The ligaments connecting the scaphoid, semi-
lunar, and cuneiform bones are —
Dorsal. Palmar.
Two Interosseous
The Dorsal Ligaments (ligamenta intercarpea dorsalia) are placed transversely
behind the bones of the first row; they connect the scaphoid and sernilunar and
the semilunar and cuneiform.
The Palmar or Volar Ligaments (ligamenta intercarpea volaria) connect the
scaphoid and semilunar and the semilunar and cuneiform bones; they are less
strong than the dorsal, and placed very deeply below the anterior ligament of
the wrist.
The Interosseous Ligaments (ligamenta intercarpea interossea) (Fig. 231) are two
narrow bundles of fibrous tissue connecting the semilunar bone on one side with
the scaphoid, and on the other with the cuneiform. They are on a level with
the superior surfaces of these bones, and close the upper part of the spaces
between them. Their upper surfaces are smooth, and form with the bones the
convex articular surfaces of the wrist-joint.
The ligaments connecting the pisiform bone are —
Capsular. Two Palmar Ligaments.
The Capsular Ligament (capsida articularis} is a thin membrane which con-
nects the pisiform bone to the cuneiform. It is lined with a separate synovial
membrane.
The Two Palmar Ligaments are two strong fibrous bands which connect the
pisiform to the unciform, the piso-uncinate ligament (ligamentum pisohamatum) ,
and to the base of the fifth metacarpal bone, the piso-metacarpal ligament (liga-
mentum pisometacarpeum) .
2. ARTICULATIONS OF THE SECOND Row OF CARPAL BONES.
These are also arthrodial joints. The articular surfaces are covered with
cartilage, and connected by the following ligaments:
Dorsal. Palmar.
Three Interosseous.
21
322 THE ARTICULATIONS OR JOINTS
The Dorsal Ligaments (ligamenta inter car pea dor solid) extend transversely from
one bone to another on the dorsal surface, connecting the trapezium with the trape-
zoid, the trapezoid with the os magnum, and the os magnum with the unciform.
The Palmar or Volar Ligaments (ligamenta intercarpea volaria) have a similar
arrangement on the palmar surface.
The Three Interosseous Ligaments (ligamenta intercarpea interossea) (Fig. 231)
much thicker than those of the first row, are placed one between the os magnum
and the unciform, a second between the os magnum and the trapezoid, and a
third between the trapezium and trapezoid. The first of these is much the
strongest, and the third is sometimes wanting.
3. ARTICULATIONS OF THE Two Rows OF CARPAL BONES WITH EACH OTHER
(Figs. 228, 229, 231).
The joint between the scaphoid, semilunar, and cuneiform, and the second row
of the carpus, or the mid-carpal joint, is made up of three distinct portions; in the
centre the head of the os magnum and the superior surface of the unciform
articulate with the deep, cup-shaped cavity formed by the scaphoid and s,emi-
lunar bones, and constitute a sort of ball-and-socket joint. On the outer side
the trapezium and trapezoid articulate with the scaphoid, and on the inner side
the unciform articulates with the cuneiform, forming gliding joints.
The ligaments are :
Anterior. External Lateral.
Posterior. Internal Lateral.
The Anterior, Palmar, or Volar Ligaments (ligamenta intercarpea volaria) consist
of short fibres, which pass, for the most part, from the palmar surface of the bones
of the first row to the front of the os magnum.
The Posterior or Dorsal Ligaments (ligamenta intercarpea dorsalid) consist of
short, irregular bundles of fibres passing between the bones of the first and second
row on the dorsal surface of the carpus.
The Lateral Ligaments are very short: they are placed, one on the radial, the
other on the ulnar side of the carpus ; the former, the stronger and more distinct,
connecting the scaphoid and trapezium bones, the latter the cuneiform and unci-
form; they are continuous with the lateral ligaments of the wrist-joint. In addi-
tion to these ligaments, a slender interosseous band sometimes connects the os
magnum and the scaphoid.
Synovial Membrane (Fig. 231). — The sy no vial membrane of the carpus is very
extensive: it passes from the under surface of the scaphoid, semilunar, and cunei-
form bones to the upper surface of the bones of the second row, sending upward
two prolongations — between the scaphoid and semilunar and the semilunar and
cuneiform ; sending downward three prolongations between the four bones of the
second row, which are further continued onward into the carpo-metacarpal
joints of the four inner metacarpal bones, and also for a short distance between
the metacarpal bones. There is a separate synovial membrane between the
pisiform and cuneiform bones.
Actions. — The articulation of the hand and wrist, considered as a whole, is
divided into three parts: (1) the radius and the interarticular fibre-cartilage;
(2) the meniscus, formed by the scaphoid, semilunar, and cuneiform, the pisiform
bone having no essential part in the movements of the hand; (3) the hand proper,
the metacarpal bones with the four carpal bones on which they are supported — viz.,
the trapezium, trapezoid, os magnum, and unciform. These three elements form
two joints: (1) the superior, wrist-joint proper, between the meniscus and bones
of the forearm; (2) the inferior, between the hand and meniscus, transverse or
mid-carpal joint.
CARPO- METACARPAL ARTICULATIONS 323
(1) The articulation between the forearm and carpus is a true condyloid artic-
ulation, and therefore all movements but rotation are permitted. Flexion and
extension are the most free, and of these a greater amount of extension than
flexion is permitted on account of the articulating surfaces extending farther on
the dorsal than on the palmar aspect of the carpal bones. In this movement the
carpal bones rotate on a transverse axis drawn between the tips of the styloid
processes of the radius and ulna. A certain amount of adduction (or ulnar
flexion) and abduction (or radial flexion) is also permitted. Of these the former
is considerably greater in extent than the latter. In this movement the carpus
revolves upon an antero-posterior axis drawn through the centre of the wrist.
Finally, circumduction is permitted by the consecutive movements of adduction,
extension, abduction, and flexion, with intermediate movements between them.
There is no rotation, but this is provided for By the supination and pronation
of the radius on the ulna. The movement of flexion is performed by the Flexor
carpi radialis, the Flexor carpi ulnaris, and the Palmaris longus; extension,
by the Extensor carpi radialis longior et brevior and the Extensor carpi
ulnaris; adduction (ulnar flexion), by the Flexor carpi ulnaris and the Ex-
tensor carpi ulnaris ; and abduction (radial flexion), by the Extensors of the
thumb and the Extensor carpi radialis longior et brevior and the Flexor carpi
radialis.
(2) The chief movements permitted in the transverse or mid-carpal joint are
flexion and extension and a slight amount of rotation. In flexion and extension,
Avhich is the movement most freely enjoyed, the trapezium and trapezoid on the
radial side and the unciform on the ulnar side glide forward and backward on the
scaphoid and cuneiform respectively, while the head of the os magnum and the
superior surface of the unciform rotate in the cup-shaped cavity of the scaphoid
and semilunar. Flexion at this joint is freer than extension. A very trifling
amount of rotation is also permitted, the head of the os magnum rotating round a
vertical axis drawn through its own centre, while at the same time a slight gliding
movement takes place in the lateral portions of the joint.
IX. Garpo-metacarpal Articulations (Articulationes Carpometacarpeae)
(Figs. 228, 229, 231).
1. ARTICULATION OF THE METACARPAL BONE OF THE THUMB WITH THE
TRAPEZIUM (ARTICULATIO CARPOMETACARPEA POLLICIS).
This is a joint of reciprocal reception, and enjoys great freedom of movement,
on account of the configuration of its articular surfaces, which are saddle-shaped,
so that, on section, each bone appears to be received into a cavity in the other,
according to the direction in which they are cut. The joint is surrounded by a
capsular ligament.
The Capsular Ligament (capsula articularis) is thick and fibrous, but loose,
and passes from the circumference of the upper extremity of the meta-
carpal bone to the rough edge bounding the articular surface of the trape-
zium; it is thickest externally and behind, and lined by a separate synovial
membrane.
Movements. — In the articulation of the metacarpal bone of the thumb with the
trapezium the movements permitted are flexion, extension, adduction, abduction,
and circumduction. When the joint is flexed the metacarpal bone is brought in
front of the palm and the thumb is gradually turned to the fingers. It is by this
peculiar movement that the tip of the thumb is opposed to the other digits; for
by slightly flexing the fingers the palmar surface of the thumb can be brought in
contact with their palmar surfaces one after another.
324
THE ARTICULATIONS OR JOINTS
2. ARTICULATIONS OF THE METACARPAL BONES OF THE FOUR INNER FINGERS
WITH THE CARPUS (ARTICULATIONES CARPOMETACARPEAE).
The joints formed between the carpus and four inner metacarpal bones are
arthrodial joints. The ligaments are —
Dorsal. Palmar.
Interosseous.
The Dorsal Ligaments (ligamenta carpometacarpea dorsalia), the strongest and
most distinct, connect the carpal and metacarpal bones on their dorsal surface.
EPIPHYSEAL
JUNCTION
MCMBRANA SACCI-
FORMIS OF INFERIOR
RADIO-ULNAR
ARTICULATION
TRIANGULAR
FIBRO-CARTILAGE
STYLOID PROCESS
OF ULNA
EPIPHYSEAL
JUNCTION
RADIO-CARPAL
ARTICULATION
INTEROSSEOUS
LIGAMENT
INTEROSSEOUS
LIGAMENT
INTERMETACAR
ARTICULATIO
INTERCARPAL
ARTICULATION
ARTICULATION OF
TRAPEZIUM AND
METACARPAL BONE
OF THUMB
CARPO-METACARPAL
ARTICULATION
METACARPAL BONES
FIG. 231. — Joints of the right hand, from the back of the hand. (Spalteholz.)
The second metacarpal bone receives two fasciculi — one from the trapezium,
the other from the trapezoid; the third metacarpal receives two — one from
the trapezoid and one from the os magnum; the fourth two — one from the os
magnum and one from the unciform; the fifth receives a single fasciculus from
the unciform bone, which is continuous with a similar ligament on the palmar
surface, forming an incomplete capsule.
The Palmar or Volar Ligaments (ligamenta carpometacarpea volaria) have a
somewhat similar arrangement on the palmar surface, with the exception of
the third metacarpal, which has three ligaments — an external one from the
CARPO-METACARPAL ARTICULATIONS
325
trapezium, situated above the sheath of the tendon of the Flexor carpi radialis;
a middle one, from the os magnum; and an internal one, from the unciform.
The Interosseous Ligaments consist of short, thick fibres, which are limited to
one part of the carpo-metacarpal articulation ; they connect the contiguous inferior
angles of the os magnum and unciform with the adjacent surfaces of the third
and fourth metacarpal bones.
Synovial Membrane. — The synovial membrane is a continuation of that between
the two rows of carpal bones. Occasionally, the articulation of the unciform
with the fourth and fifth metacarpal bones has a separate synovial membrane.
The synovial membranes of the wrist and carpus (Fig. 231) are thus seen to
be five in number. The first, the membrana sacciformis or the recessus sacciformis
of the inferior radio-ulnar articulation, passes from the lower end of the ulna to
TENDON OF FLEXOR
SUBLIMIS DIGITORUM
TENDON OF FLEXOR
PROFUNDUS DIGITORUM
ANTERIOR
OR VAGINAL
LIGAMENT
TRANSVERSE
METACARPAL
LIGAMENT
LATERAL
LIGAMENT
SECOND LUM-
BRICAL MUSCLE
ANTERIOR OR SECOND
VAGINAL LIGAMENT PALMAR
INTEROSSEOUS
MUSCLE
TRANSVERSE META-
CARPAL LIGAMENT
ANTERIOR OR
VAGINAL LIGAMENT
FIG. 232. — Metacarpal bones and first phalanges of the second to the fifth finger of the right hand, with
ligaments, from the volar surface. (Spalteholz.)
the sigmoid cavity of the radius, and lines the upper surface of the interarticular
fibro-cartilage. The second passes from the lower end of the radius and inter-
articular fibro-cartilage above to the bones of the first row below, The third,
the most extensive, passes between the contiguous margins of the two rows of
carpal bones — between the bones of the second row to the carpal extremities of
the four inner metacarpal bones. The fourth, from the margin of the trapezium
to the metacarpal bone of the thumb. The fifth, between the adjacent margins
of the cuneiform and pisiform bones.
Actions. — The movement permitted in the carpo-metacarpal articulations of the
four inner fingers is limited to a slight gliding of the articular surfaces upon each
other, the extent of which varies in the different joints. Thus the articulation of the
metacarpal bone of the little finger is most movable, then that of the ring finger.
The metacarpal bones of the index and middle fingers are almost immovable.
326
THE ARTICULATIONS OR JOINTS
3. ARTICULATIONS OF THE METACARPAL BONES WITH EACH OTHER (ARTICU-
LATIONES INTERMETACARPEAE (Figs. 228, 229, 231).
The carpal extremities of the four inner metacarpal bones articulate with
one another at each side by small surfaces covered with cartilages, and connected
together by dorsal, palmar, and interosseous ligaments.
The Dorsal Ligaments (ligamenta basium oss. metacarp. dorsalia) and Palmar
Ligaments (ligamenta basium oss. metacarp. volarid) pass transversely from one
bone to another on the dorsal and palmar sur-
»O P&
faces.
The Interosseous Ligaments (ligamenta basium
oss. metacarp. interossea) pass between their con-
tiguous surfaces, just beneath their lateral artic-
ular facets.
Synovial Membrane (Fig. 231). — The synovial
membrane between the lateral facets is a reflec-
tion from that between the two rows of carpal
fiii bones.
The Transverse Metacarpal Ligament (liga-
mentum capitulorum oss. metacarpalium trans-
versum] (Fig. 232) is a narrow, fibrous band
which passes transversely across the anterior sur-
faces of the digital extremities of the four inner
metacarpal bones, connecting them together. It
is blended anteriorly with the palmar ligaments
of the metacarpo-phalangeal articulations. To
its posterior border is connected the fascia which
covers the Interossei muscles. Its anterior sur-
face is concave where the flexor tendons pass
over it. Behind it the tendons of the Interossei
muscles pass to their insertion.
ARTICULAR
CAPSULE
ARTICULAR.
CAPSULE
ARTICULAR
CAPSULE"
LATERAL
"LIGAMEM
X. Metacarpo-phalangeal Articulations ( Artic-
ulationes Metacarpophalangeae)
(Figs. 232, 233).
These articulations are of the condyloid kind,
formed by the reception of the rounded head of
the metacarpal bone into a shallow cavity in the
extremity of the first phalanx. The expansion
of the extensor tendon acts as a dorsal ligament.
There is a capsular ligament which at certain
points has strengthening ligaments. The liga-
.ments are —
Anterior.
Two Lateral.
The Anterior, Palmar, or Vaginal Ligament
(glenoid ligament of Cruveilhier, ligamentnm
vaqinale) is a thick, dense, fibrous structure,
FIG. 233. — Metacarpal bones and first i i ' .1 i <> j> -r • • , • ±1
halanges of the third finger of the right placed on the palmar surrace ot the joint in the
interval between the lateral ligaments, to which
it is connected; it is loosely united to the meta-
carpal bone, but very firmly to the base of the first phalanx. Its palmar surface
is intimately blended with the transverse metacarpal ligament, and presents a
THE HIP -JOINT
327
groove for the passage of the flexor tendons, the sheath surrounding which is
connected to each side of the groove. By its deep surface it forms part of the
articular surface for the head of the metacarpal bone, and is lined by a synovial
membrane.
The Lateral or Collateral Ligaments (ligamenta collateralid) are strong, rounded
cords placed one on each side of the joint, each being attached by one extremity
to the posterior tubercle on the side of the head of the metacarpal bone, and by
the other to the contiguous extremity of the phalanx.
Actions. — The movements which occur in these joints are flexion, extension,
adduction, abduction, and circumduction; the lateral movements are very limited.
Surface Form. — The prominences of the knuckles do not correspond to the position of the
joints either of the metacarpo-phalangeal or interphalangeal articulations. These prominences
are invariably formed by the distal ends of the proximal bone of each joint, and the line indi-
cating the position of the joint must be sought considerably in front of the middle of the knuckle.
The usual rule for finding these joints is to flex the distal phalanx on the proximal one to a right
angle; the position of the joint is then indicated by an imaginary line drawn along the middle of
the lateral aspect of the proximal phalanx.
XI. Articulations of the Phalanges (Articulationes Digitorum Maims
(Fig. 233).
These are ginglymus joints. Each joint has a capsule, and certain accentuated
portions are regarded as definite ligaments. These ligaments are —
Anterior or Palmar. Two Lateral (ligamenta collateralia).
The arrangement of these ligaments is similar to those in the metacarpo-
phalangeal articulations; the extensor tendon supplies the place of a dorsal
ligament.
Actions. — The only movements permitted in the phalangeal joints are flexion
and extension; these movements are more extensive between the first and second
phalanges than between the second and third. The movement of flexion is very
considerable, but extension is limited by the anterior and lateral ligaments.
ARTICULATIONS OF THE LOWER EXTREMITY.
The articulations of the Lower Extremity comprise the following groups:
I. The Hip-joint.
II. The Knee-joint.
III. The Articulations between the
Tibia and Fibula.
IV. The Ankle-joint.
V. The Articulations of the Tarsus.
VI. The Tarso-metatarsal Articulations.
VII. Articulations of the Metatarsal
Bones with each other.
VIII. The Metatarso-phalangeal Artic-
ulations.
IX. The Articulations of the Phalanges.
I. The Hip-joint (Articulatio Coxae) (Figs. 234, 235, 236, 237, 238, 239).
This articulation is an enarthrodial or ball-and-socket joint, formed by the
reception of the head of the femur into the cup-shaped cavity of the acetabulum.
The articulating surfaces are covered with cartilage, that on the head of the femur
being thicker at the centre than at the circumference, and covering the entire
surface, with the exception of a depression just below its centre for the ligamen-
tum teres; that covering the acetabulum is much thinner at the centre than at
the circumference. It forms an incomplete cartilaginous ring of a horseshoe
shape, being deficient below, where there is a circular depression, which is occu-
328
THE ARTICULATIONS OR JOINTS
pied in the recent state by a mass of fat covered by synovial membrane. The
ligaments of the joints are the
Capsular.
Ilio-femoral.
Transverse.
Teres.
Cotyloid.
The Capsular Ligament (capsula articularis) (Figs. 234, 235, 237, and 239) is a
strong, dense, ligamentous capsule, embracing the margin of the acetabulum
above and surrounding the neck of the femur below. Its upper circumference
ANTERIOR
INTERTRO
CHANTERIC LINE
FIG. 234.— Right hip-joint, from in front. (Spalteholz.)
is attached to the acetabulum, above and behind, two or three lines external
to the cotyloid ligament; but in front it is attached to the outer margin of
this ligament, and opposite to the notch, where the margin of this cavity is
deficient, it is connected to the transverse ligament, and by a few fibres to
the edge of the obturator foramen. Its lower circumference surrounds the neck
of the femur, being attached, in front, to the spiral or anterior intertrochanteric
line; above, to the base of the neck; behind, to the neck of the bone, about half
THE HIP-JOINT
329
an inch above the posterior intertrochanteric line. From this insertion the fibres
are reflected upward over the neck of the femur, forming a sort of tubular sheath,
the cervical reflection, which blends with the periosteum and can be traced as fur
as the articular cartilage. On the surface of the neck of the femur some of these
reflected fibres are raised into longitudinal folds, termed retinacula. It is much
thicker at the upper and forepart of the joint, where the greatest amount of
FIG. 235. — Right hip-joint, from behind. (The joint capsule, except for the strengthening ligaments, has
been removed.) (Spalteholz.)
resistance is required, than below and internally, where it is thin, loose, and
longer than in any other part. It consists of two sets of fibres,, circular and lon-
gitudinal. The circular fibres, zona orbicularis (Fig. 237) , are most abundant at the
lower and back part of the capsule, and form a sling or collar around the neck of
the femur. Anteriorly they blend with the deep surface of the ilio-femoral .liga-
ment, and through its medium reach the anterior inferior spine of the ilium. The
longitudinal fibres are greatest in amount at the upper and front part of the cap-
sule, where they form distinct bands or accessory ligaments, of which the most
important is the ilio-femoral. Other accessory bands are known as the pubo-
330
femoral or pubo-capsular ligament (ligamentum pubocapsulare) , passing from the
outer portion of the horizontal pubic ramus, the ilio-pectineal eminence, the
obturator crest and the obturator membrane, to the front of the capsule; and
ischio-capsular ligament or ligament of Bertin (ligamentum ischiocapsulare) ,
passing from the ischium, just below the acetabulum, to blend with the circular
fibres at the lower part of the joint. The external surface is rough, covered by
numerous muscles, and separated in front from the Psoas and Iliacus muscles by
a synovial bursa, which not infrequently communicates, by a circular aperture,
with the cavity of the joint. It differs from the capsular ligament of the shoulder
in being much less loose and lax, and in not being perforated for the passage of
a tendon.
ANTERIOR
INFERIOR
SPINE OF ILIUM
SPINE OF
ISCHIUM
TRANSVERSE
LIGAMENT OF
ACETABULUM
TUBEROSITV
'OF ISCHIUM
FIG. 236. — Right hip-joint from the medial side. (The bottom of the acetabulum has been chiselled away
sufficiently to make the head of the femur visible.) (Spalteholz.)
The Ilio-femoral or Y-ligament or Ligament of Bigelow (ligamentum ilio-
femorale) (Figs. 234, 235, 237, and 238) is an accessory band of fibres extending
obliquely across the front of the joint; it is intimately connected with the cap-
sular ligament, and serves to strengthen it in this situation. It is attached,
above, to the lower part of the anterior inferior spine of the ilium and the
adjacent rim of* the acetabulum; and, diverging below, forms two bands, of
which one passes downward to be inserted into the lower part of the anterior
intertrochanteric line; the other passes downward and outward to be inserted
into the upper part of the same line and the adjacent part of the neck of the
femur. Between the two bands is a thinner part of the capsule. Sometimes
there is no division, but the ligament spreads out into a flat, triangular band,
which is attached below into the whole length of the anterior intertrochanteric
line. This ligament is frequently called the Y-shaped ligament of Bigelow; and
THE HIP -JOINT
331
the outer or upper of the two bands is sometimes described as a separate liga-
ment, under the name of the ilio-trochanteric ligament.
The Ligamentum Teres, or the Interarticular Ligament (ligamentum teres femoris)
(Figs. 236, 237, and 239) is a triangular band implanted by its apex into the
depression a little behind and below the centre of the head of the femur, and by
its broad base into the margins of the cotyloid notch, becoming blended with the
transverse ligament. It is formed of connective tissue, surrounded by a tubular
sheath of synovial membrane. Sometimes only the synovial fold exists. Very
rarely it is absent. The ligament is made tense when the hip is semiflexed,
ILIOLUMBAR LIGAMENT
ANTERIOR SACRO-
ILIAC LIGAMENT
CAPSULAR LIGAMENT.
FIBROUS PORTION
CAPSULAR LIGAMENT,
SYNOVIAL PORTION
ILIOYEMORAL
LIGAMENT
ZONA
ORBICULARIS
GREAT
TROCHANTER
COOPER'S LIGAMENT
SPINE OF PUBIS
PUBOFEMORAL
LIGAMENT
OBTURATOR LIGAMENT
ZONA ORBICULARIS
SMALL SYNOVIAL MEMBRANE COVERING
TROCHANTER NECK OF FEMUR
FIG. 237. — The right hip-joint, seen from before. (Toldt.)
and the limb adducted and rotated outward; it is, on the other hand, relaxed
when the limb is abducted. It has, however, but little influence as a ligament,
though it may to a certain extent limit movement, and would appear to be
merely a "vestigial and practically useless ligament."1 It is probably a modifi-
cation of the folds which in other joints fringe the margins of reflection of synovial
membranes.
The Cotyloid Ligament (labrum glenoidale] (Fig. 239) is a fibro-cartilaginous rim
attached to the margin of the acetabulum, the cavity of which it deepens; at the
1 J. Bland Sutton. Ligaments: Their Nature and Morphology.
332
THE ARTICULATIOS OR JOINTS
same time it protects the edges of the bone and fills up the inequalities on its sur-
face. It bridges over the notch as the transverse ligament of the acetabulum, and
thus forms a complete circle, which closely sur-
rounds the head of the femur, and assists in
holding it in its place, acting as a sort of valve.
It is prismoid on section, its base being attached
to the margin of the acetabulum and its op-
posite edge being free and sharp; whilst its
two surfaces are invested by synovial mem-
brane, the external one being in contact with
the capsular ligament, the internal one being
inclined inward, so as to narrow the acetab-
ulum and embrace the cartilaginous surface
of the head of the femur. It is much thicker
above and behind than below and in front,
and consists of close, compact fibres, which
arise from different points of the circumference
of the acetabulum and interlace with each other
at very acute angles.
The transverse ligament of the acetabulum
(ligamentum tramversum acetabuli) (Figs. 236
and 239) is in reality a portion of the cotyloid
ligament, though differing from it in having
no cartilage-cells amongst its fibres. It con-
sists of strong, flattened fibres, which cross the
notch at the lower part of the acetabulum and
convert it into a foramen. Thus an interval
is left beneath the ligament for the passage of
nutrient vessels to the joint.
Synovial Membrane (Figs. 237 and 239). — The synovial membrane is very
extensive. Commencing at the margin of the cartilaginous surface of the head
of the femur, it covers all that portion of the neck which is contained within the
joint; from the neck it is reflected on the internal surface of the capsular liga-
ment, covers both surfaces of the cotyloid ligament and the mass of fat contained
in the depression at the bottom of the acetabulum, and is prolonged in the form
of a tubular sheath around the ligamentum teres, as far as the head of the femur.
It sometimes communicates through a hole in the capsular ligament between
the inner band of the Y-shaped ligament and the pubo-femoral ligament with
a bursa situated on the under surface of the Ilio-psoas muscle.
The muscles in relation with the joint (Fig. 240) are, in front, the Psoas and
Iliacus, separated from the capsular ligament by a synovial bursa; above, the
reflected head of the Rectus and Glutens minimus, the latter being closely adherent
to the capsule ; internally, the Obturator externus and Pectineus ; behind, the Pyri-
formis, Gemellus superior, Obturator internus, Gemellus inferior, Obturator exter-
nus, and Quadratus femoris.
The arteries supplying the joint are derived from the obturator, sciatic, internal
circumflex, and gluteal.
The nerves are articular branches from the sacral plexus, great sciatic, obtu-
rator, accessory obturator, and a filament from the branch of the anterior crural
supplying the rectus.
Bursse. — Numerous bursse exist in the neighborhood of the hip-joint. Some
anatomists have counted twenty-one (Synnestredt). The chief ones are : 1. The
ilio-pectineal bursa (bursa iliopectinea) (Fig. 240), between the ilio-psoas tendon
and the capsule of the joint. It often communicates with the hip-joint. 2. The
FIG. 238. — Hip-joint, showing the ilio-femoral
ligament. (After Bigelow.)
THE HIP -JOINT
333
subtendinous iliac bursa (bursa iliaca subtendinea) , between the tendon of the psoas
and iliacus and the lesser trochanter. 3. The ischio-gluteal bursa (bursa ischiadica
m. glutaei maximi) , between the Gluteus maximus muscle and the tuberosity of the
ischium (not constant). 4. The bursa of the great trochanter (bursa trochanterica m.
glutcei maximi), between the great trochanter and the Gluteus maximus muscle
near the muscular insertion, o. Two or three gluteo-femoral bursae (bursce
glutccofemorales) below. 6. The obturator bursa (bursa m. obturatorii interni),
between the margin of the great sacro-sciatic notch and the tendon of the
Obturator internus muscle. 7. The subcutaneous trochanteric bursa (bursa tro-
GREAT
TROCHANTER
EPIPHYSEAL
JUNCTION
FIG. 239. — Right hip-joint. Frontal section. Posterior half, viewed from in front. (The joint surfaces
have been somewhat pulled apart.) (Spalteholz.)
chanterica subcutanea) , between the cutaneous surface and the great trochanter.
Besides these there is a bursa between the great trochanter and the anterior part
of the Gluteus medius — between the great trochanter and the posterior part of
the Gluteus medius — between the great trochanter and the Gluteus minimus —
beneath the Pyriformis muscle — between the small trochanter and the Quad-
ratus femoris muscle, and there are bursae beneath the Biceps femoris muscle.
Actions. — The movements of the hip are very extensive, and consist of flexion,
extension, adduction, abduction, circumduction, and rotation.
334
THE ARTICULATIONS OR JOINTS
The hip-joint presents a very striking contrast to the shoulder-joint in the
much more complete mechanical arrangements for its security and for the limita-
tion of its movements. In the shoulder, as we have seen, the head of the humerus
is not adapted at all in size to the glenoid cavity, and is hardly restrained in any
of its ordinary movements by the capsular ligament. In the hip-joint, on the
contrary, the head of the femur is closely fitted to the acetabulum for a distance
extending over nearly half a sphere, and at the margin of the bony cup it is still
more closely embraced by the cotyloid ligament, so that the head of the femur
is held in its place by that ligament even when the fibres of the capsule have been
quite divided (Humphry). The anterior portion of the capsule, described as the
ilio-femoral ligament, is the strongest of all the ligaments in the body, and is put
on the stretch by any attempt to extend the femur beyond a straight line with the
trunk. That is to say, this ligament is the chief agent in maintaining the erect
position without muscular fatigue; for a vertical line passing through the centre
of gravity of the trunk falls behind the centres of rotation in the hip-joints, and
Ileo-fem. ligament
Isch. caps,
ligament.
Pub. fern, ligament
FIG. 240. — Relation of muscles to hip-joint. (Henle.)
therefore the pelvis tends to fall backward, but is prevented by the tension of
the ilio-femoral and capsular ligaments. The security of the joint may be also
provided for by the two bones being directly united through the ligamentum
teres; but it is doubtful whether this so-called ligament can have much influence
upon the mechanism of the joint. Flexion of the hip-joint is arrested by the soft
parts of the thigh and abdomen being brought into contact when the leg is flexed
on the thigh; and by the action of the hamstring muscles when the leg is extended;1
extension, by the tension of the ilio-femoral ligament and front of the capsule;
adduction, by the thighs coming into contact; adduction, with flexion by the
outer band of the ilio-femoral ligament, the outer part of the capsular ligament:
1 The hip-joint cannot be completely flexed, in most persons, without at the same time flexing the knee, on
account of the shortness of the hamstring muscles. — Cleland, Jour, of Anat. and Phys., No. 1, Old Series, p. 87.
DR' M' LEWIS EMERSON .
THE HIP -JOINT 335
abduction, by the inner band of the ilio-femoral ligament and the pubo-femoral
band; rotation outward, by the outer band of the ilio-femoral ligament; and
rotation inward, by the ischio-capsular ligament and the hinder part of the cap-
sule. The muscles which flex the femur on the pelvis are the Psoas, Iliacus,
Rectus, Sartorius, Pectineus, Adductor longus and brevis, and the anterior fibres
of the Gluteus medius and minimus. Extension is mainly performed by the
Gluteus maximus, assisted by the hamstring muscles. The thigh is adducted by
the Adductor magnus, longus, and brevis, the Pectineus, the Gracilis, and lower
part of the Gluteus maxirnus, and abducted by the Gluteus medius and minimus
and upper part of the Gluteus maximus. The muscles which rotate the thigh
inward are the anterior fibres of the Gluteus medius, the Gluteus minimus, and the
Tensor fascia femoris; while those which rotate it outward are the posterior fibres
of the Gluteus medius, the Pyriformis, Obturator externus and internus, Gemellus
superior and inferior, Quadratus femoris, Iliacus, Gluteus maximus, the three
Adductors, the Pectineus, and the Sartorius.
Surface Form. — A line drawn from the anterior superior spinous process of the ilium to
the most prominent part of the tuberosity of the ischium (Nelaton's line) runs through the
centre of the acetabulum, and would, therefore, indicate the level of the hip-joint; or, in other
words, the upper border of the great trochanter, which lies on Nelaton's line, is on a level with
the centre of the hip-joint.
Surgical Anatomy. — Inflammation of bursce about the hip-joint gives rise to confusing
symptoms. Inflammation of one of the bursse over the great trochanter is not uncommon.
Great pain is produced if any movement of the gluteal muscles is permitted.
Enlargement of the bursa over the ischial tuberosity was long called weaver's button. Enlarge-
ment of the bursa beneath the ilio-psoas may produce a large swelling. Bursal inflammation is
not unusually mistaken for hip-joint disease
In dislocation of the hip "the head of the thigh bone may rest at any point around its socket"
(Bryant); but whatever position the head ultimately assumes, the primary displacement is
generally downward and inward, the capsule giving way at its weakest — that is, its lower and
inner — part. The situation that the head of the bone subsequently assumes is determined
by the degree of flexion or extension, and of outward or inward rotation of the thigh at the
moment of luxation, influenced, no doubt, by the ilio-femoral ligament, which is not easily
ruptured. When, for instance, the head is forced backward, this ligament forms a fixed axis,
round which the head of the bone rotates, and the head is thus driven on to the dorsum of the ilium.
The ilio-femoral ligament also influences the position of the thigh in the various dislocations:
in the dislocations backward it is tense, and produces inversion of the limb; in the dislocation
on to the pubes it is relaxed, and therefore allows the external rotators to evert the thigh; while
in the»thyroid dislocation it is tense and produces flexion. The muscles inserted into the upper
part of the femur, with the exception of the Obturator internus, have very little direct influence
in determining the position of the bone. But Bigelow has endeavored to show that the Obtu-
rator internus is the principal agent in determining whether in the backward dislocations the
head of the bone shall be ultimately lodged on the dorsum of the ilium or in or near the sciatic
notch. In both dislocations the head passes, in the first instance, in the same direction; but,
as Bigelow asserts, in the displacement on to the dorsum, the head of the bone travels up behind
the acetabulum, in front of the muscle; while in the dislocation into the sciatic notch, the head
passes behind the muscle, and is therefore prevented from reaching the dorsum, in consequence
of the tendon of the muscle arching over the neck of the bone, and so remains in the neighbor-
hood of the sciatic notch. Bigelow, therefore, distinguishes these two forms of dislocation by
describing them as dislocations backward, "above and below," the Obturator internus.
The ilio-femoral ligament is rarely torn in dislocations of the hip, and this fact is taken
advantage of by the surgeon in reducing these dislocations by manipulation. It is made to act
as a fulcrum to a lever, of which the long arm is the shaft of the femur, and the short arm the
neck of the bone.
The hip-joint is rarely the seat of acute synovitis from injury, on account of its deep position
and its thick covering of soft parts. Acute inflammation may, and does, frequently occur as
the result of constitutional conditions, as rheumatism, pyaemia, etc. When, in these cases,
effusion takes place, and the joint becomes distended with fluid, the swelling is not very easy
to detect on account of the thickness of the capsule and the depth of the articulation. It is
principally to be found on the front of the joint, just internal to the ilio-femoral ligament; or
behind, at the lower and back part. In these two places the capsule is thinner than elsewhere.
Disease of the hip-joint is much more frequently of a chronic character and is usually of tuber-
culous origin. It begins either in the bones or in the synovial membrane, more frequently in the
336 THE ARTICULATIONS OR JOINTS
formef, and probably, in most cases, in the growing, highly vascular tissue in the neighborhood'
of the epiphysial cartilage. In this respect it differs very materially from tuberculous arthritis-
of the knee, where the disease often commences in the synovial membrane. The reasons why
hip-disease so frequently begins near the epiphysial cartilage are twofold: first, this part being
the centre of rapid growth, its nutrition is unstable and inflammation is easily awakened;,
and, secondly, great strain is thrown upon it, from the frequency of falls and blows upon the hip,
which causes crushing of the epiphysial cartilage or the cancellous tissue in its neighborhood,
with the results likely to follow such an injury. In addition to these, the depth of the joint
protects it from the causes of synovitis.
In chronic hip-disease the affected limb assumes an altered position, the cause of which it
is important to understand. In the early stage of a typical case the limb is flexed, abducted,
and rotated outward. In this position all the ligaments of the joint are relaxed: the front of
the capsule by flexion; the outer band of the ilio-femoral ligament by abduction; and the inner
band of this ligament and the back of the capsule by rotation outward. It is, therefore, the
position of the greatest ease. The condition is not quite obvious at first upon examining a-
patient. If the patient is laid in the supine position, the affected limb will be found to be
extended and parallel with the other. But it will be found that the pelvis is tilted downward
on the diseased side and the limb apparently longer than its fellow, and that the lumbar spine
is arched forward (lordosis). If now the thigh is abducted and flexed, the tilting down-
ward and the arching forward of the pelvis disappears. The condition is thus explained. A
limb which is flexed and abducted is obviously useless for progression, and, to overcome the
difficulty, the patient depresses the affected side of his pelvis in order to produce parallelism
of his limbs, and at the same time rotates his pelvis on its transverse horizontal axis, so as to
direct the limb downward instead of forward. In the latter stages of the disease the limb
becomes flexed, adducted, and inverted. The position probably depends upon muscular
action, at all events as regards the adduction. The Adductor muscles are supplied by the
obturator nerve, which also largely supplies the joint. These muscles are therefore thrown into
reflex action by the irritation of the peripheral terminations of this nerve in the inflamed artic-
ulation. Osteo-arthritis is not uncommon in the hip-joint, and it is said to be more common in
the male than in the female, in whom the knee-joint is more frequently affected. It is a disease
of middle age or more advanced period of life.
Congenital dislocation is more commonly met with .in the hip-joint than in any other articula-
tion. The displacement usually takes place on to the dorsum ilii. It gives rise to extreme
lordosis, and a waddling gait is noticed as soon as the child commences to walk.
Excision of the hip may be required for disease or for injury, especially for gunshot wound.
It may be performed either by an anterior or an external incision. The former one entails
less interference with important structures, especially muscles, than the posterior one, but permits
of less efficient drainage. In these days, however, when the surgeon aims at securing healing
of his wound without suppuration, this second advantage is not of so much importance. In
the operation in front the surgeon makes an incision three or four inches in length, starting
immediately below and external to the anterior superior spinous process of the ilium, down-
ward and inward between the Sartorius and Tensor fasciae femoris, to the neck of the^bone,
dividing the capsule at its upper part. A narrow-bladed saw now divides the neck of the femur,
and the head of the bone is extracted with sequestrum forceps. All diseased tissue is carefully
removed with a sharp spoon or scissors, and the cavity thoroughly flushed with a hot aseptic
fluid.
The external method consists in making an incision three or four inches long, commencing
midway between the top of the great trochanter and the anterior superior spine, and ending
over the shaft, just below the trochanter. The muscles are detached from the great trochanter,
and the capsule opened freely. The head and neck are freed from the soft parts and the bone
sawn through just below the top of the trochanter with a narrow saw. The head of the bone is
then levered out of the acetabulum. In both operations, if the acetabulum is eroded, it must be
freely gouged.
II. The Knee-joint (Articulatio Genu).
The knee-joint was formerly described as a ginglymus or hinge-joint, but is
really of a much more complicated character. It must be regarded as consist-
ing of three articulations in one : one between each condyle of the femur and the
corresponding tuberosity of the tibia, which are condyloid joints, and one between
the patella and the femur, which is partly arthrodial, but not completely so, since
the articular surfaces are not mutually adapted to each other, so that the movement
is not a simple gliding one. This view of the construction of the knee-joint receives
confirmation from the study of the articulation in some of the lower mammals,
THE KNEE-JOINT
337
where three synovial membranes are sometimes found, corresponding to these
three subdivisions, either entirely distinct or only connected together by small
communications. This view is further rendered probable by the existence
of the two crucial ligaments within the joint, which must be regarded as the
external and internal lateral ligaments of the inner and outer joints respectively.
The existence of the ligamentum mucosum would further indicate a tendency
to separation of the synovial cavity into two minor sacs, one corresponding to
each joint.
The bones entering into the formation of the knee-joint are the condyles of the
femur above, the head of the tibia below, and the patella in front. The bones are
connected together by ligaments, some of which are placed on the exterior of the
joint, while others occupy its interior.
External Ligaments.
Anterior, or Ligamentum Patellae.
Posterior.
Internal Lateral.
Two External Lateral. (The long
external ligament is constant. The
short external ligament is not always
present.)
Capsular.
Interior Ligaments.
Anterior, or External Crucial.
Posterior, or Internal Crucial.
Two Semilunar Fibro-cartilages.
Transverse.
Coronary.
T - f Processes of
Ligamentum mucosum. c . ,
, . bvnovial
Ligarnenta alarm. Membrane.
The Anterior Ligament, or Ligamentum Patellae (Figs. 241, 245, and 246), is the
central portion of the common tendon of the Extensor muscles of the thigh, which
is continued from the patella to the tubercle of the tibia, supplying the place of an
anterior ligament. It is a strong, flat, ligamentous band about three inches in
length, attached, above, to the apex of the patella and the rough depression on its
posterior surface ; below, to the lower part of the tubercle of the tibia, its superficial
fibres being continuous over the front of the patella with those of the tendon of the
Quadriceps extensor. The lateral portions of the tendon of the Extensor muscles
pass down on either side of the patella, and are attached to the borders of this bone.
The deep fascia and the quadriceps extensor muscle are inserted into the patella.
Prolongations from the fascia and from the fibrous expansion of the muscle pass
from the edges of the patella and from the ligament of the patella to the upper
extremity of the tibia on each side of the tubercle; externally, and to the head of
the fibula. They are termed lateral patellar ligaments (retinaculum patellae mediate
and retinaculum patellae laterale), and merge into the capsule. The posterior
surface of the ligamentum patellae is* separated from the front of the capsular
ligament by a mass of fat.
The Posterior Ligament (ligamentum popliteum obliquum) (Fig. 241) is a broad,
flat, fibrous band, formed of fasciculi separated from one another by apertures
for the passage of vessels and nerves. It is attached, above, to the upper margin
of the intercondyloid notch of the femur, and, below, to the posterior margin of
the head of the tibia. Superficial to the main part of the ligament and forming
a portion of it is a strong fasciculus derived from the tendon of the Semi-
membranosus, and passing from the back part of the inner tuberosity of the tibia
obliquely upward and outward to the back part of the outer condyle of the femur.
This expansion from the tendon of the Semimembranosus muscle is called the
posterior ligament of Winslow (ligamentum posticum Winslowii), and it merges
with the posterior ligament. The posterior ligament forms part of the floor of
the popliteal space, and the popliteal artery rests upon it.
The Internal Lateral Ligament (ligamentum collateral tibiale) (Figs. 241 and 242)
is a broad, flat, membranous band, thicker behind than in front, and situated
22
338
THE ARTICULATIONS OR JOINTS
nearer to the back than the front of the joint. It is attached, above, to the inner
tuberosity of the femur; below, to the inner tuberosity and inner surface of the
shaft of the tibia to the extent of about two inches. It is crossed, at its lower
part, by the tendons of the Sartorius, Gracilis, and Semitendinosus muscles, a
synovial bursa being interposed. Its deep surface covers the anterior portion of
the tendon of the Semimembranosus, with which it is connected by a few fibres,
the synovial membrane of the joint, and the inferior internal articular vessels and
nerve; it is intimately adherent to the internal semilunar fibro-cartilage.
FIG. 241. — Right knee-joint. Anterior view.
FIG. 242. — Right knee-joint. Posterior view.
The External Lateral or Long External Lateral Ligament ( ligamentum collaterale
fibulare) (Figs. 242 and 246) is a strong, rounded, fibrous cord situated nearer
to the back than the front of the joint. It is attached, above, to the back part
of the outer tuberosity of the femur; below, to the outer part of the head of the
fibula. Its outer surface is covered by the tendon of the Biceps, which divides at
its insertion into two parts, separated by the ligament. The ligament has, pass-
ing beneath it, the tendon of the Popliteus muscle and the inferior -external
articular vessels and nerve.
The Short External Lateral Ligament (ligamentum later ale externum breve sen
posticum) (Fig. 242) is not a constant structure. It is an accessory bundle of
fibres placed behind and parallel with the preceding, attached, above, to the
lower and back part of the outer tuberosity of the femur; below, to the summit
of the styloid process of the fibula. This ligament is intimately connected with
the capsular ligament, and has, passing beneath it, the tendon of the Popliteus
muscle and the inferior external articular vessels and nerve.
THE KNEE-JOINT
339
The Capsular Ligament (capsula articularis) (Fig. 241) consists of an exceedingly
thin but strong, fibrous membrane which fills in the intervals left between the
stronger bands above described, and is inseparably connected with them. In front
it blends with and forms part of the lateral Femur.
patellar ligaments and fills in the interval
between the anterior and lateral ligaments of
the joints, with which latter structures it is
closely connected. It is deficient above the
joint and beneath the tendon of the quadri-
ceps extensor. Behind, it is formed chiefly
of vertical fibres, which arise above from
the condyles and intercondyloid notch of
the femur, and is connected below with the
back part of the head of the tibia, being
closely united with the origins of the Gas-
trocnemius, Plantaris, and Popliteus muscles.
It passes in front of, but is inseparably con-
nected with, the posterior ligament.
The Crucial Ligaments (ligamenta cruciata
genii) (Figs. 172, 243, and 244) are two inter-
osseous ligaments of considerable strength
situated in the interior of the joint, nearer its
posterior than its anterior part. They are
called crucial because they cross each other
somewhat like the lines of the letter X; and
have received the names anterior crucial and
posterior crucial, from the position of their at-
tachment to the tibia.
The anterior or external crucial ligament
(ligamentum cruciatum anterius) (Fig. 243) is
attached to the depression in front of the
spine of the tibia, being blended with the anterior extremity of the external
semilunar fibro-cartilage, and, passing obliquely upward, backward, and out-
ward, is inserted into the inner and back part of the outer condyle of the femur.
The posterior or internal crucial ligament (ligamentum cruciatum posterius)
is stronger, but shorter and 4ess oblique in its direction than the anterior. It
is attached to the back part
of the depression behind the
spine of the tibia, to the pop^
liteal notch, and to the poste-
rior extremity of the external
semilunar fibro-cartilage; and
passes upward, forward, and
inward, to be inserted into
the outer and forepart of the
inner condyle of the femur.
It is in relation, in front, with
the anterior crucial ligament ;
behind, with the capsular liga-
ment.
The Semilunar Fibro-cartil-
ages(menmc) (Figs. 172, 243,
244, 245, and 246) are two crescentic lamellae which serve to deepen the surface
of the head of the tibia, for articulation with the condyles of the femur. The
FIG. 243. — Right knee-joint,
ligaments.
Showing internal
FIG. 244. — Head of tibia, with semilunar cartilages, etc.
from above. Right side.
Seen
340
THE ARTICULATIONS OR JOINTS
circumference of each cartilage is thick, convex, and attached to the inside of the
capsule of the knee ; the inner border is thin, concave, and free. Their upper
surfaces are concave, and in relation with the condyles of the femur; their lower
surfaces are flat, and rest upon the head of the tibia. Each cartilage covers
nearly the outer two-thirds of the corresponding articular surface of the tibia,
leaving the inner third uncovered ; both surfaces are smooth and invested by
synovial membrane.
SUPRAPATELLAR
BURSA
TENDON OF QUADRICEPS
EXTENSOR FEMORIS
EXTERNAL
SEMILUNAR
FIBRO-CARTILAGE
EPIPHYSEAL.
JUNCTION
ARTICULAR
CAVITY
LIGAMENTA
ALARIA
LIGAMENTUM
PATELLA:
DEEP INFRA-
PATELLAR BURSA
TUBEROSITY
OF TIBIA
FIG. 245. — Right knee-joint. Sagittal section through the external condyle of the femur. Medial half of
section, from the lateral side. (The knee is slightly flexed; the joint surfaces have been pulled a little apart.)
(Spalteholz.)
The internal semilunar fibro-cartilage (meniscus medialis] is nearly semicircular
in form, a little elongated from before backward, and broader behind than in front;
its anterior extremity, thin and pointed, is attached to a depression on the anterior
margin of the head of the tibia, in front of the anterior crucial ligament; its
posterior extremity is attached to the depression behind the spine, between the
attachments of the external semilunar fibro-cartilage and the posterior crucial
ligaments.
THE KNEE-JOINT
341
The external semilunar fibro-cartilage (meniscus lateralis) forms nearly an
entire circle, covering a larger portion of the articular surface than the internal
one. It is grooved on its outer side for the tendon of the Popliteus muscle. Its
extremities, at their insertion, are interposed between the two extremities of the
internal semilunar fibro-cartilage; the anterior extremity being attached in front
of the spine of the tibia to the outer side of, and behind, the anterior crucial
TENDON OF QUAD-
RICEPS EXTENSOR
FEMORIS
SUPRAPATELLAR
BURSA
ARTICULAR
CAVITY
SHWFT OF THE,/
/fl ,
T I B I A
LONG EXTERNAL
LATERAL
LIGAMENT
TENDON OF
POPLITEUS
MUSCLE
POPLITEAL
BURSA
HEAD OF
FIBULA
PREPATELLAR
BURSA
EXTERNAL SEMI-
LUNAR FIBRO-
CARTILAGE
LIGAMENTUM
PATELL/E
DEEP INFRAPATEL-
LAR BURSA
TUBEROSITV
OF TIBIA
FIG. 246. — Right knee-joint, from the lateral surface. (The joint cavity and several bursse have been injecteu
with a stiffening medium and then dissected out.) (Spalteholz.)
ligament, with which it blends ; the posterior extremity being attached behind the
spine of the tibia, in front of the posterior extremity of the internal semilunar
fibro-cartilage. Just before its insertion posteriorly it gives off a strong fasciculus,
the ligament of Wrisberg, which passes obliquely upward and outward, to be
inserted into the inner condyle of the femur, close to the attachment of the poste-
rior crucial ligament. Occasionally a small fasciculus is given off which passes
forward to be inserted into the back part of the anterior crucial ligament. The
342 THE ARTICULATIONS OR JOINTS
external semilunar fibro-cartilage gives off from its anterior convex margin a
fasciculus which forms the transverse ligament.
The Transverse Ligament (ligamentum transversum genu) (Fig. 244) is a band of
fibres which passes transversely from the anterior convex margin of the external
semilunar fibro-cartilage to the anterior convex margin of the internal semilunar
fibro-cartilage ; its thickness varies considerably 'in different subjects, and it is
sometimes absent altogether.
The Coronary Ligaments (ligamenta coronaria) are merely portions of the cap-
sular ligament, which connect the circumference of each of the semilunar fibro-
~
cartilages with the margin of the head of the tibia.
Synovial Membrane (Figs. 245 and 246) . — The synovial membrane encloses the
articular cavity (cavum articulare) of the knee-joint. It is the largest and most
extensive synovial membrane in the body. Commencing above the upper border
of the patella, it forms a short cul-de-sac beneath the Quadriceps extensor tendon of
the thigh, on the lower part of the front of the shaft of the femur; this communi-
cates, by an orifice of variable size, with a synovial bursa interposed between the
tendon and the front of the femur (bursa suprapatellaris) . On each side of the
patella the synovial membrane extends beneath the aponeurosis of the Vasti
muscles, and more especially beneath that of the Vastus internus. Below the
patella it is separated from the anterior ligament by the anterior part of the
capsule and a considerable quantity of adipose tissue, known as the infrapatellar
pad (Fig. 245) . In this situation the synovial membrane sends off a triangular
prolongation, containing a few ligamentous fibres, which extends from the ante-
rior part of the joint below the patella to the front of the intercondyloid notch.
This fold has been termed the ligamentum mucosum (plica synomalis patellaris}.
It also sends off two fringe-like folds, called the ligamenta alaria (pliccs alares)
(Fig. 245), which extend from the sides of the ligamentum mucosum, upward
and laterally between the patella and femur. On either side of the joint it passes
downward from the femur, lining the capsule to its point of attachment to the
semilunar cartilages; it may then be traced over the upper surfaces of these car-
tilages to their free borders, and from thence along their under surfaces to the
tibia. At the back part of the external one it forms a cul-de-sac between the
groove on its surface and the tendon of the Popliteus; it surrounds the crucial
ligaments and lines the inner surface of the ligaments which enclose the joint.
The pouch of synovial membrane between the Extensor tendon and front of the
femur is supported, during the movements of the knee, by a small muscle, the
Subcrureus, which is inserted into the upper part of the capsular ligament.
The folds of synovial membrane and the fatty processes contained in them act,
as it seems, mainly in padding to fill up interspaces and obviate concussions.
Sometimes the bursa beneath the Quadriceps extensor is completely shut off from
the rest of the synovial cavity, thus forming a closed sac between the Quadriceps
and the lower part of the front of the femur; sometimes it communicates with the
synovial cavity by a minute aperture; usually the two cavities are incompletely
separated by a synovial fold.
Bursse. — The bursse about the knee-joint are the following: In front there
are four bursae: one is interposed between the patella and the skin. It is
known as the prepatellar bursa (bursa prcepatellaris subcutanea); another, of
small size, between the upper part of the tuberosity of the tibia and the
ligamentum patellae is called the deep infrapatellar bursa (bursa infrapatellaris-
profunda); and a third between the lower part of the tuberosity of the tibia
and the skin, the subcutaneous tibial bursa (bursa subcutanea tuberositatis tibice).
A fourth bursa exists in front, the suprapatellar bursa (bursa suprapatellaris).
It lies between the anterior surface of the lower end of the femur and the
posterior surface of the quadriceps femoris. Spalteholz says that the supra-
THE KNEE-JOINT 343
patellar bursa is closely connected with the quadriceps tendon and is usually
incompletely shut off from the cavity of the joint.1 Occasionally there is a
bursa between the expansion of the fascia lata and the Quadriceps and' the
patella (bursa pracpatellaris subfascialis) , and sometimes one between the tendon
of the quadriceps and the anterior surface of the patella (bursa prcppatellaris
subtendinea) . On the outer side there are four bursae: (1) one beneath the. outer
head of the Gastrocnemius (which sometimes communicates with the joint);
(2) one above the external lateral ligament between it and the tendon of the
Biceps; (3) one beneath the external lateral ligament between it and the tendon
of the Popliteus (this is sometimes only an expansion from the next bursa);
(4) one beneath the tendon of the Popliteus (bursa musculi poplitei) between it
and the condyle of the femur, which is almost always an extension from the syno-
vial membrane of the joint. On the inner side there are five bursae: (1) one
beneath the inner head of the Gastrocnemius, which sends a prolongation between
the tendons of the Gastrocnemius and Semimembranosus : this bursa often com-
municates with the joint; (2) one above the internal lateral ligament between it
and the tendons of the Sartorius, Gracilis, and Semitendinosus; (3) one beneath
the internal lateral ligament between it and the tendon of the Semimembra-
nosus: this is sometimes only an expansion from the next bursa; (4) one beneath
the tendon of the Semimembranosus, between it and the head of the tibia;
(5) sometimes there is a bursa between the tendons of the Semimembranosus
and of the Semitendinosus.
Structures around the Joint. — In front and at the sides, the Quadriceps extensor;
on the outer side, the tendons of the Biceps and the Popliteus and the external
popliteal nerve; on the inner side, the Sartorius, Gracilis, Semitendinosus, and
Semimembranosus; behind, an expansion from the tendon of the Semimembra-
nosus, the popliteal vessels, and the internal popliteal nerve, the Popliteus, the
Plantaris, and the inner and outer heads of the Gastrocnemius, some lymphatic
glands, and fat.
The arteries supplying the joint are derived from the anastomotica magna
branch of the femoral, articular branches of the popliteal, anterior and posterior
recurrent branches of the anterior tibial, and a descending branch from the
external circumflex of the Profunda.
The nerves are derived from the obturator, anterior crural, and external and
internal popliteal.
Actions. — The knee-joint permits of movements of flexion and extension, and,
in certain positions, of slight rotation inward and outward. The movement of
flexion and extension does not, however, take place in a simple, finger-like man-
ner, as in other joints, but is a complicated movement, consisting of a certain
amount of gliding and rotation; so that the same part of one articular surface is
not always applied to the same part of the other articular surface, and the axis
of motion is not a fixed one. If the joint is examined while in a condition of
extreme flexion, the posterior part of the articular surfaces of the tibia will be
found to be in contact with the posterior rounded extremities of the condyles of
the femur; and if a simple hinge-like movement were to take place, the axis,
round which the revolving movement of the tibia occurs, would be in the back
part of the condyle. If the leg is now brought forward into a position of semi-
flexion, the upper surface of the tibia will be seen to glide over the condyles of
the femur, so that the middle part of the articular facets are in contact, and the
axis of rotation must therefore have shifted forward to nearer the centre of the
condyles. If the leg is now brought into the extended position, a still further
gliding takes place and a further shifting forward of the axis of rotation. This
1 Spalteholz's Hand Atlas of Human Anatomy. Translated by Lewellys F. Barker.
344 THE ARTICULATIONS OR JOINTS
is not, however, a simple movement, but is accompanied by a certain amount of
rotation outward round a vertical axis drawn through the centre of the head of
the tibia. This rotation is due to, the greater length of the internal condyle, and
to the fact that the anterior portion of its articular surface is inclined obliquely
outward. In consequence of this it will be seen that toward the close of the
movement of extension — that is to say, just before complete extension is effected
— the tibia glides obliquely upward and outward over this oblique surface on the
inner condyle, and the leg is therefore necessarily rotated outward. In flexion
of the joint the converse of these movements takes place: the tibia glides backward
round the end of the femur, and at the commencement of the movement the tibia
is directed downward and inward along the oblique curve of the inner condyle,
thus causing an inward rotation to the leg.
During flexion and extension the patella moves on the lower end of the femur,
but this movement is not a simple gliding one; for if the articular surface of this
bone is examined, it will be found to present on each side of the central vertical
ridge two less marked transverse ridges, which divide the surface, except a small
portion along the inner border, which is cut off by a slight vertical ridge into
six facets (see Fig. 247), and therefore does not present a uniform curved surface
as would be the case if a simple gliding movement took
place. These six facets — three on each side of the
median vertical ridge — correspond to and denote the
parts of the bone respectively in contact with the con-
dyles of the femur during flexion, semiflexion, and exten-
sion. In flexion only the upper facets on the patella are
in contact with the condyles of the femur; the lower
two-thirds of the bone rests upon the mass of fat which
occupies the space between the femur and tibia. In the
semiflexed position of the joint the middle facets on the
FIG 247 —view of the pos- patella rest upon the most prominent portion of the con-
terior surface of the patella, dyles, and thus afford greater leverage to the Quadriceps
showing diagrammatically the • • • • T p * «
areas of contact with the femur by increasing its distance trom the centre ot motion. In
in different positions of the , ., n . , Al ,
knee. complete extension the patella is drawn up, so that only
the lower facets are in contact with the articular sur-
faces of the condyles. The narrow strip along the inner border is in contact
with the outer aspect of the internal condyle when the leg is fully flexed at
the knee-joint. As in the elbow, so it is in the knee — the axis of rotation in
flexion and extension is not precisely at right angles to the axis of the bone, but
during flexion there is a certain amount of alteration of plane; so that, whereas in
flexion the femur and tibia are in the same plane, in extension the one bone forms
an angle of about 10 degrees with ithe other. There is, however, this difference
between the two extremities: that in the upper, during extension, the humeri are
parallel and the bones of the forearm diverge; in the lower, the femora converge
below and the tibia are parallel.
In addition to the slight rotation during flexion and extension, the tibia enjoys
an independent rotation on the condyles of the femur in certain positions of the
joint. This movement takes place between the interarticular fibro-cartilages and
the tibia, whereas the movement of flexion and extension takes place between the
interarticular fibro-cartilages and the femur. So that the knee may be said to
consist of two joints, separated by the fibro-cartilages: an upper, menisco-femoral,
in which flexion and extension take place; and a lower, menisco-tibial, allowing
of a certain amount of rotation. This latter movement can only take place in the
semiflexed position of the limb, when all the ligaments are relaxed.
During flexion the ligamentum patellae is put upon the stretch, as is also the
posterior crucial ligament in extreme flexion. The other ligaments are all relaxed
THE KNEE-JOINT 345
by flexion of the joint, though the relaxation of the anterior crucial ligament is
very trifling. During life flexion is checked by the contact of the leg with the
thigh. In the act of extending the leg upon the thigh the ligamentum patella is
tightened by the Quadriceps extensor; but when the leg is fully extended, as in the
erect posture, the ligament becomes relaxed, so as to allow free lateral movement to
the patella, which then rests on the front of the lower end of the femur. The other
ligaments, with the exception of the posterior crucial, which is partly relaxed, are all
on the stretch. When the limb has been brought into a straight line, extension is
checked mainly by the tension of all the ligaments except the posterior crucial and
ligamentum patella?. The movements of rotation of which the knee is capable are
permitted in the semiflexed condition by the partial relaxation of both crucial liga-
ments, as well as of the lateral ligaments. Rotation inward appears to be limited
by the tension of the anterior crucial ligament, and by the interlocking of the two
ligaments; but rotation outward does not appear to be checked by either crucial
ligament, since they uncross during the execution of this movement, but it is
checked by the lateral ligaments, especially the internal. The main function of
the crucial ligaments is to act as a direct bond of union between the tibia and
femur, preventing the former bone from being carried too far backward or
forward. Thus the anterior crucial ligament prevents the tibia being carried
too far forward by the extensor tendons, and the posterior crucial checks too
great movement backward by the flexors. They also assist the lateral ligaments
in resisting any lateral bending of the joint. The interarticular cartilages are
intended, as it seems, to adapt the surface of the tibia to the shape of the femur
to a certain extent, so as to fill up the intervals which would otherwise be felt
in the varying positions of the joint, and to interrupt the jars which would be
so frequently transmitted up the limb in jumping or falls on the feet; also to
permit of the two varieties of motion, flexion and extension, and rotation, as
explained above. The patella is a great defence to the knee-joint from any
injury inflicted in front, and it distributes upon a large and tolerably even sur-
face during kneeling the pressure which would otherwise fall upon the prominent
ridges of the condyles ; it also affords leverage to the Quadriceps extensor muscle
when it acts upon the tibia; and Mr. Ward has pointed out1 how this leverage
varies in the various positions of the joint, so that the action of the muscles pro-
duces velocity at the expense of force in the commencement of extension, and, on
the contrary, at the close of extension tends to diminish velocity, and therefore
the shock to the ligaments at the moment tension of the structures takes place.
Extension of the leg on the thigh is performed by the Quadriceps extensor;
flexion by the hamstring muscles, assisted by the Gracilis and Sartorius, and,
indirectly, by the Gastrocnemius, Popliteus, and Plantaris; rotation outward, by
the Biceps ; and rotation inward by the Popliteus, Semitendinosus, and, to a slight
extent, the Semimembranosus, the Sartorius, and the Gracilis.
Surface Form. — The interval between the two bones entering into the formation of the knee-
joint can always easily be felt. If the limb is extended, it is situated on a slightly higher level
than the apex of the patella ; but if the limb is slightly flexed, a knife carried horizontally back-
ward immediately below the apex of the patella would pass directly into the joint. When the
knee-joint is distended with fluid, the outline of the synovial membrane at the front of the knee
may be fairly well mapped out.
Surgical Anatomy. — The bursts about the knee are frequently the seat of inflammation.
Enlargement of the prepatellar bursa constitutes housemaid' s knee. The bursa beneath the
Semimembranosus may enlarge greatly. It communicates with the knee-joint and can frequently
be made to disappear by pressure when the knee is flexed. Treves points out that enlargement
of the bursa between the biceps tendon and the external lateral ligament causes great pain
because the peroneal nerve crosses the sac.2
From a consideration of the construction of the knee-joint it would at first sight appear to be
1 Human Osteology, p. 405. * Applied Anatomy.
346 THE ARTICULATIONS OR JOINTS
one of the least secure of any of the joints in the body. It is formed between the two longest
bones, and therefore the amount of leverage which can be brought to bear upon it is very con-
siderable; the articular surfaces are but ill adapted to each other, and the range and variety of
motion which it enjoys is great. All these circumstances tend to render the articulation very
insecure; but, nevertheless, on account of the very powerful ligaments which bind the bones
together, the joint is one of the strongest in the body, and dislocation from traumatism is of
very rare occurrence. When, on the other hand, the ligaments have been softened or destroyed
by disease, partial displacement is very liable to occur, and is frequently brought about by the
mere action of the muscles displacing the articular surfaces from each other. The tibia may
be dislocated in any direction from the femur — forward, backward, inward, or outward; or a
combination of two of these dislocations may occur — that is, the tibia may be dislocated for-
ward and laterally, or backward and laterally, and any of these dislocations may be complete
or incomplete. As a rule, however, the antero-posterior dislocations are complete, the lateral
ones incomplete.
One or other of the semilunar cartilages may become displaced and nipped between the
femur and tibia. The accident is produced by a twist of the leg when the knee is flexed, and is
accompanied by a sudden pain and fixation of the knee in a flexed position. The cartilage may
be displaced either inward or outward: that is to say, either inward toward the tibial spine, so
that the cartilage becomes lodged in the intercondyloid notch; or outward, so that the car-
tilage projects beyond the margin of the articular surface. Acute synovitis, the result of trau-
matism or exposure to cold, is very common in the knee, on account of its superficial position.
When distended with fluid, the swelling shows itself above and at the sides of the patella, reach-
ing about an inch or more above the trochlear surface of the femur, and extending a little higher
under the Vastus internus than the Vastus externus. Occasionally the swelling may extend
two inches or more. At the sides of the patella the swelling extends lower at the inner side
than it does on the outer side. The lower level of the synovial membrane is just above the
level of the upper part of the head of the fibula. In the middle line it covers the upper third
of the ligamentum patellae, being separated from it, however, by the capsule and a pad of fat.
Chronic synovitis principally shows itself in the form of pulpy degeneration of the synovial mem-
brane, the result of tuberculous arthritis. The reasons why tuberculous disease of the knee
so often commences in the synovial membrane appear to be the complex and extensive nature of
this sac; the extensive vascular supply to it; and the fact that injuries are generally diffused
and applied to the front of the joint rather than to the ends of the bones. Syphilitic disease
not unfrequently attacks the knee-joint. In the hereditary form of the disease it is usually
symmetrical, attacking both joints, which become filled with synovial effusion, and is very intract-
able and difficult to cure. In the tertiary stage of acquired syphilis gummatous infiltration of
the synovial membrane may take place. The knee is one of the joints most commonly affected with
osteo-arthritis, and is said to be more frequently the seat of this disease in wromen than in men.
The occurrence of the so-called loose cartilage is almost confined to the knee, though loose cartilages
are occasionally met with in the elbow, and, rarely, in some other joints. Many of them occur in
cases of osteo-arthritis, in which calcareous or cartilaginous material is formed in one of the synovial
fringes and constitutes the foreign body, and may or may not become detached, in the former
case only meriting the usual term, " loose" cartilage. In other cases they have their origin in the
exudation of inflammatory lymph, and possibly, in some rare instances, a portion of the articular
cartilage or one of the semilunar cartilages becomes detached and constitutes the foreign body.
Genu valgum, or knock-knee, is a common deformity of childhood, in which, owing to
changes in and about the joint, the angle between the outer border of the tibia and femur is
diminished, so that as the patient stands the two internal condyles of the femora are in contact,
but the two internal malleoli of the tibiae are more or less widely separated from each other.
When, however, the knees are flexed to a right angle, the two legs are practically parallel with
each other. At the commencement of the disease there is a yielding of the internal lateral liga-
ment and other fibrous structures on the inner side of the joint; as a result of this there is a
constant undue pressure of the outer tuberosity of the tibia against the outer condyle of the
femur. This extra pressure causes arrest of growth and, possibly, wasting of the outer con-
dyle, and a consequent tendency for the tibia to become separated from the internal condyle.
To prevent this the internal condyle becomes depressed; probably, as was first pointed out by
Mikulicz, by an increased growth of the lower end of the diaphysis on its inner side, so that the
line of the epiphysis becomes oblique instead of transverse to the axis of the bone, with a direc-
tion downward and inward. It is often said that the deformity is produced by undue length
of the inner condyle, but in reality the condyle grows as the deformity progresses.
Excision of the knee-joint is most frequently required for tuberculous disease of this articula-
tion, but is also practised in cases of disorganization of the knee after rheumatic fever, pyaemia,
etc., in osteo-arthritis, and in ankylosis. It is also occasionally called for in cases of injury, gun-
shot or otherwise. The operation is best performed either by a horseshoe incision, starting from
one condyle, descending as low as the tubercle of the tibia, where it crosses the leg, and is then
carried upward to the other condyle; or by a transverse incision across the patella. In this
TIBIO - FIB ULAR ARTICULA TION
TUBEROSITV
'OF TIBIA
latter incision the patella is either removed or sawn across, and the halves subsequently sutured
together. The bones having been cleared, and in those cases where the operation is performed
for tuberculous disease all pulpy tissue having been carefully removed, the section of the femur
is first made. This should never include, in children, more than, at the most, two-thirds of
the articular surface, otherwise the epiphysial cartilage will be involved, with disastrous results
as regards the growth of the limb. Afterward a thin slice should be removed from the upper
end of the tibia, not more than half an inch. If any diseased tissue still appears to be left in the
bones, it should be removed with the gouge rather than by making a further section of the bones.
III. Tibio-fibular Articulation
(Articulatio Tibiofibularis) .
The articulations between the tibia
and fibula are effected by ligaments
which connect both extremities, as
well as the shafts of the bones. It
may, consequently, be subdivided
into three articulations: 1. The
superior tibio-fibular articulation, 2.
The middle tibio-fibular ligament or
interosseous membrane. 3. The
inferior tibio-fibular articulation.
1. SUPERIOR TIBIO-FIBULAR ARTIC-
ULATION (ARTICULATIO
TIBIOFIBULARIS).
This articulation is an arthrodial
joint. The contiguous surfaces of
the bones present two flat, oval
facets covered -with cartilage, and
connected together by the following
ligaments :
Capsular.
Anterior Superior Tibio-fibular.
Posterior Superior Tibio-fibular.
The Capsular Ligament (capsula
articularis) consists of a membra-
nous bag which surrounds the artic-
ulation, being attached around the
margins of the articular facets on
the tibia and fibula, and is much
thicker in front than behind.
The new nomenclature considers
the anterior and posterior ligaments
as one ligament (ligamentum capituli
fibulce).
The Anterior Superior Ligament
(Fig. 248) consists of two or three
broad and flat bands which pass
obliquely upward and inward from
the front of the head of the fibula
to the front of the outer tuberosity
of the tibia.
The Posterior Superior Ligament
(Fig. 241) is a single thick and
INNER
MALLEOLUS
OUTER
MALLEOLUS
ANTERIOR LIGAMENT
OF OUTER
MALLEOLUS
FIG. 248. — Ligaments of the right leg, from in front.
(Spalteholz.)
348 THE ARTICULATIONS OR JOINTS
broad band which passes upward and inward from the back part of the head of
the fibula to the back part of the outer tuberosity of the tibia. It is covered by
the tendon of the Popliteus muscle.
Synovial Membrane. — A sy no vial membrane lines this articulation, which at its
upper and back part is occasionally continuous with that of the knee-joint.
2. MIDDLE TIBIO-FIBULAR LIGAMENT OR INTEROSSEOUS MEMBRANE
(MEMBRANA INTEROSSEA CRURIS) (Fig. 248).
An interosseous membrane extends between the contiguous margins of the
tibia, and fibula and separates the muscles on the front from those on the back
of the leg. It consists of a thin, aponeurotic lamina composed of oblique fibres
which for the most part pass downward and outward between the interosseous
ridges on the two bones ; some few fibres, however, pass in the opposite direction,
downward and inward. It is broader above than below. Its upper margin does
not quite reach the superior tibio-fibular joint, but presents a free concave border,
above which is a large, oval aperture for the passage of the anterior tibial vessels
forward to the anterior aspect of the leg. At its lower part is an opening for the
passage of the anterior peroneal vessels. It is continuous below with the inferior
interosseous ligament, and is perforated in numerous places for the passage of small
vessels. It is in relation, in front, with the Tibialis anticus, Extensor longus digi-
torum, Extensor proprius hallucis, Peroneus tertius, and the anterior tibial vessels
and nerve; behind, with the Tibialis posticus and Flexor longus hallucis.
3. INFERIOR TIBIO-FIBULAR ARTICULATION (SYNDESMOSIS TIBIOFIBULARIS)
(Figs. 250, 251, 252).
This articulation is formed by the rough, convex surface of the inner side of
the lower end of the fibula, connected with a concave rough surface on the outer
side of the tibia. Below, to the extent of about two lines, these surfaces are smooth,
and covered with cartilage, which is continuous with that of the ankle-joint. The
ligaments of this joint are —
Anterior Inferior Tibio-fibular. Transverse or Inferior.
Posterior Inferior Tibio-fibular. Inferior Interosseous.
The Anterior Inferior Ligament (ligamentum malleoli later alls anterius) (Figs. 248
and 252) is a flat, triangular band of fibres, broader below than above, which extends
obliquely downward and outward, between the adjacent margins of the tibia and
fibula, on the front aspect of the articulation. It is in relation, in front, with the
Peroneus tertius, the aponeurosis of the leg, and the integument; behind, with
the inferior interosseous ligament; and lies in contact with the cartilage covering
the astragalus.
The Posterior Inferior Ligament (ligamentum malleoli lateralis posterius) (Fig.
252) , smaller than the preceding, is disposed in a similar manner on the posterior
surface of the articulation.
The Transverse Ligament or Inferior Ligament lies under cover of the posterior
ligament, and is a strong, thick band of yellowish fibres which passes transversely
across the back of the joint, from the external malleolus to the posterior border of
the articular surface of the tibia, almost as far as its malleolar process. This liga-
ment projects below the margin of the bones, and forms part of the articulating
surface for the astragalus.
The Inferior Interosseous Ligament (Fig. 250) consists of numerous short, strong,
fibrous bands which pass between the contiguous rough surfaces of the tibia and
fibula, and constitute the chief bond of union between the bones. This ligament
is continuous above with the interosseous membrane.
THE TIBIO-TARSAL ARTICULATION
349
Synovial Membrane. — The synovial membrane lining the articular surface is
derived from that of the ankle-joint (Fig. 250).
Actions. — The movement permitted in these articulations is limited to a very
slight gliding of the articular surfaces one upon another.
IV. The Tibio-tarsal Articulation or Ankle-joint (Articulatio Talocruralis)
(Figs. 249, 250, 251, 252).
The ankle is a ginglymus or hinge-joint. The bones entering into its formation
are the lower extremity of the tibia and its malleolus and the external malleolus
Ta rso- metatarsal
articulations, N-
Tarsal articulations.
FIG. 249. — Ankle-joint: tarsal and tarso-metatarsal articulations. Internal view. Right side.
of the fibula, which forms a mortise (Fig. 248) to receive the upper convex surface
of the astragalus and its two lateral facets. The bony surfaces are covered with car-
tilage and connected together by a capsule (capsula articularis) , which in places
forms thickened bands constituting the following ligaments:
Anterior. Internal Lateral.
Posterior. External Lateral.
The Anterior Tibio-tarsal Ligament (ligamentum talotibiale anterius) is a broad,
thin, membranous layer, attached, above, to the anterior margin of the lower
extremity of the tibia; below, to the margin of the astragalus, in front of its artic-
ular surface. It is in relation, in front, with the Extensor tendons of the toes, with
the tendons of the Tibialis anticus and Peroneus tertius, and the anterior tibial
vessels and nerve; behind, it lies in contact with the synovial membrane.
The Posterior Tibio-tarsal Ligament (ligamentum talotibiale posterius) is very
thin, and consists principally of transverse fibres. It is attached, above, to the
margin of the articular surface of the tibia, blending with the transverse tibio-
fibular ligament; below, to the astragalus, behind its superior articular facet.
Externally, where a somewhat thickened band of transverse fibres is attached to
the hollow on the inner surface of the external malleolus, it is thicker than inter-
nally.
350
THE ARTICULATIONS OR JOINTS
The Internal Lateral or Deltoid Ligament (ligamentum calcaneotibiale or ligamentum
deltoideum) (Figs. 249, 250, and 251) is a strong, flat, triangular band, attached,
above, to the apex and anterior and posterior borders of the inner malleolus.
The most anterior fibres pass forward to be inserted into the scaphoid bone and
the inferior calcaneo-scaphoid ligament; the middle descend almost perpendicu-
larly to be inserted into the sustentaculum tali of the os calcis; and the posterior
fibres pass backward and outward to be attached to the inner side of the astragalus.
This ligament is covered by the tendons of the Tibialis posticus and Flexor longus
digitorum muscles.
The External Lateral Ligament (ligamenta talofibularia et calcaneofibulare) (Figs.
251 and 252) consists of three distinctly specialized fasciculi of the capsule,
taking different directions and separated by distinct intervals; for which reason
it is described by some anatomists as three distinct ligaments.1
The anterior fasciculus (ligamentum talofibulare anterius), the shortest of the
three, passes from the anterior margin of the external malleolus forward and
inward to the astragalus, in front of its external articular facet.
INTEROSSEOUS,
LIGAMENT
SYNOVIAL
ADIPOSE PAD
PERONEUS
BREVIS MUSCLE
PERONEU
LONGUS MUSCLE
INTERNAL LATERAL
LIGAMENT
TIBIALIS POSTICUS
INTEROSSEOUS CAL-
CANEO-ASTRAGALOID
LIGAMENT
FLEXOR LONGUS
DIGITORUM
FLEXOR LONGUS
HALLUCIS
POSTERIOR
TIBIAL VESSELS
FIG. 250. — Frontal section through the ankle-joint and the calcaneo-astragaloid articulation.
(Pcirier and Charpy).
The posterior fasciculus (ligamentum talofibulare posterius), the most deeply seated,
passes inward from the depression at the inner and back part of the external mal-
leolus to a prominent tubercle on the posterior surface of the astragalus. Its fibres
are almost horizontal in direction.
The middle fasciculus (ligamentum calcaneofibulare) (Figs. 251 and 252), the
longest of the three, is a narrow, rounded cord passing from the apex of the
external malleolus downward and slightly backward to a tubercle on the outer
surface of the os calcis. It is covered by the tendons of the Peroneus longus and
brevis.
Synovial Membrane.— The synovial membrane (Fig. 250; invests the inner
surface of the ligaments, and sends a duplicature upward between the lower
extremities of the tibia and fibula for a short distance.
1 Humphry. On the Skeleton, p. 559.
THE TIBIO-TARSAL ARTICULATION
351
Relations. — The tendons, vessels, and nerves in connection with the joint are,
in front, from within outward, the Tibialis anticus, Extensor proprius hallucis,
anterior tibial vessels, anterior tibial nerve, Extensor longus digitorum, and Pero-
neus tertius; behind, from within outward, the Tibialis posticus, Flexor longus
n.
in.
INTERNAL
INTEROSSEOUS
LIGAMENT
TARSO-
METATARSAL
ARTICULATIONS
INTEROSSEOUS
LIGAMENT
ASTRAGALO-
SCAPHOIO
ARTICULATION
TENDON OF POS-
TERIOR TIBIAL
MUSCLE
INTEROSSEOUS
LIGAMENTS
INTERMETATARSAL
ARTICULATIONS
INTEROSSEOUS
LIGAMENT
CALCANEO-SCAPHOID
LIGAMENT
CALCANEO-CUBOIO
ARTICULATION
INTEROSSEOUS
LIGAMENT
ASTRAGALO-CALCANEAL
— ARTICULATION
ANKLE-JOINT
MIDDLE FASCICULUS
OF THE EXTERNAL
LATERAL LIGAMENT
INFERIOR TIBIO-
FI8ULAR ARTICULATION
FIG. 251. — Joints of the right foot, from the back of the foot. (Spalteholz.)
digitorum, posterior tibial vessels, posterior tibial nerve, Flexor longus hallucis;
and in the groove behind the external malleolus, the tendons of the Peroneus
longus and brevis.
The arteries supplying the joint are derived from the malleolar branches of
the anterior tibial and the peroneal.
352
The nerves are derived from the anterior and posterior tibial.
Actions. — The movements of the joint are those of flexion and extension.
Flexion consists in the approximation of the dorsum of the foot to the front of the
leg, while in extension the heel is drawn up and the toes pointed downward. The
malleoli tightly embrace the astragalus in all positions of the joint, so that any
slight degree of lateral movement which may exist is simply due to stretching
of the inferior tibio-fibular ligaments and slight bending of the shaft of the fibula.
Of the ligaments, the internal, or deltoid, is of very great power — so much so
that it usually resists a force which fractures the process of bone to which it is
attached. Its middle portion, together with the middle fasciculus of the external
lateral ligament, binds the bones of the leg firmly to the foot and resists displace-
ment in every direction. Its anterior and posterior fibres limit extension and
flexion of the foot respectively, and the anterior fibres also limit abduction. The
posterior portion of the external lateral ligament assists the middle portion in
resisting the displacement of the foot backward, and deepens the cavity for the
Inferior tibio-fibidar articulation.
Ankle-joint.
Tarsal articulations.
FIG. 252. — Ankle-joint: tarsal and tarso-metatarsal articulations. External view. Right side.
reception of the astragalus. The anterior fasciculus is a security against the dis-
placement of the foot forward, and limits extension of the joint. The movements
of inversion and eversion of the foot, together with the minute changes in form by
which it is applied to the ground or takes hold of an object in climbing, etc., are
mainly effected in the tarsal joints, the one which enjoys the greatest amount of
motion being that between the astragalus and os calcis behind and the scaphoid
and cuboid in front. This is often called the transverse or medio-tarsal joint, and
it can, with the subordinate joints of the tarsus, replace the ankle-joint in a great
measure when the latter has become ankylosed.
Extension of the tarsal bones upon the tibia and fibula is produced by the
Gastrocnemius, Soleus, Plantaris, Tibialis posticus, Peroneus longus and brevis,
Flexor longus digitorum, and Flexor longus hallucis; flexion, by the Tibialis anti-
cus, Peroneus tertius, Extensor longus digitorum, and Extensor proprius hallucis1
1 The student must bear in mind that the Extensor longus digitorum and Extensor proprius hallucis are
extensors of the toes, but flexors of the ankle, and that the Flexor longus digitorum and Flexor longus hallucis
are flexors of the toes, but extensors of the ankle. — ED. of 15th English Edition.
THE TIBIO-TARSAL ARTICULATION
353
(Fig. 251); inversion, in the extended position, is produced by theTibialis anticus
and posticus; and eversion by the Peronei.
FIG. 253. — Section of the right foot near its inner border, dividing the tibia, astragalus, calcaneus, scaphoid,
internal cuneiform, and first metatarsal bone, and the first phalanx of the great toe. (After Braune.)
Surface Form. — The line of the ankle-joint may be indicated by a transverse line drawn
across the front of the lower part of the leg, about half an inch above the level of the tip of the
internal malleolus.
Surgical Anatomy. — Displacement of the trochlear surface of the astragalus from the tibio-
fibular mortise is not of common occurrence, as the ankle-joint is a very strong and powerful
articulation, and great force is required to produce dislocation. Nevertheless, dislocation does
occasionally occur, both in an antero-posterior and a lateral direction. In the latter, which is the
most common, fracture is a necessary accompaniment of the injury. The dislocation in these cases
is somewhat peculiar, and is not a displacement in a horizontally lateral direction, such as usually
occurs in lateral dislocations of ginglymoid joints, but the astragalus undergoes a partial rotation
round an antero-posterior axis drawn through its own centre, so that the superior surface, instead
of being directed upward, is inclined more or less inward or outward according to the variety of
the displacement.
The ankle-joint is more frequently sprained than any joint in the body, and this may lead
to acute synovitis. In these cases, when the synovial sac is distended with fluid, the bulging
appears principally in the front of the joint, beneath the anterior tendons, and on either side,
between the tibialis anticus and the internal lateral ligament on the inner side, and between the
Peroneus tertius and the external lateral ligament on the outer side. In addition to this, bulging
frequently occurs posteriorly, and a fluctuating swelling may be detected on either side of the
tendo Achillis.
Chronic synovitis may result from frequent sprains, and when once this joint has been
sprained it is more liable to a recurrence of the injury than it was before; chronic synovitis
may be tuberculous in its origin, the disease usually commencing in the astragalus and extending
to the joint, though it may commence as a synovitis the result probably of some slight strain in
a tuberculous subject.
Excision of the ankle-joint is not often performed for two reasons. In the first place, disease
of the articulation for which this operation is indicated is frequently associated with disease of
the tarsal bones, which prevents its performance; and, secondly, the foot after excision is fre-
quently of very little use; far less, in fact, than after a Syme's amputation, which is often, there-
fore, a preferable operation in these cases. Excision may, however, be attempted in a case of
tuberculous arthritis in a young and otherwise healthy subject, where the disease is limited to
the bones forming the joint. It may also be required after injury where the vessels and nerves
have not been damaged and the patient is young and free from visceral disease. The excision is
best performed through two lateral incisions. One commencing two and a half inches above the
external malleolus, carried down the posterior border of the fibula, round the end of the bone,
and then forward and downward as far as the calcaneo-cuboid joint, midway between the tip
of the external malleolus and the tuberosity on the fifth metatarsal bone. Through this incision
23
354 THE ARTICULATIONS OR JOINTS
the fibula is cleared, the external lateral ligament is divided, and the bone sawn through about
half an inch above the level of the ankle-joint and removed. A similar curved incision is now
made on the inner side of the foot, commmencing two and a half inches above the lower end of
the tibia, carried down the posterior border of the bone, round the internal malleolus, and for-
ward and downward to the tuberosity of the scaphoid bone. Through this incision the tibia is
cleared in front and behind, the internal lateral, the anterior and posterior ligaments divided,
and the end of the tibia protruded through the wound by displacing the foot outward, and sawn
off sufficiently high to secure a healthy section of bone. The articular surface of the astragalus
is now to be sawn off or the whole bone removed. In cases where the operation is performed
for tuberculous arthritis the latter course is probably preferable, as the injury done by the saw is
frequently the starting point of fresh caries; and after removal of the whole bone the shortening
is not appreciably increased, and the result as regards union appears to be as good as when two
sawn surfaces of bone are brought into apposition.
V. Articulations of the Tarsus (Articulationes Intertarseae) (Figs. 249,
251, 252, 254, 255).
1. ARTICULATION OF THE Os CALCIS AND ASTRAGALUS OR THE CALCANEO-
ASTRAGALOID ARTICULATION (ARTICULATIO TALOCALCANEA) (Fig. 251).
The articulations between the os calcis and astragalus are two in number —
anterior and posterior. They are arthrodial joints. The bones are connected
together by a capsule (capsula articularis) , which is at certain points accentuated
into definite ligaments. There are five ligaments in this articulation:
External Calcaneo-astragaloid. Anterior Calcaneo-astragaloid.
Internal Calcaneo-astragaloid. Posterior Calcaneo-astragaloid.
Interosseous.
The External Calcaneo-astragaloid Ligament (ligamentum talocalcaneum laterale)
(Fig. 252) is a short, strong, fasciculus passing from the outer surface of the
astragalus, immediately beneath its external malleolar facet, to the outer surface
of the os calcis. It is placed in front of the middle fasciculus of the external
lateral ligament of the ankle-joint, with the fibres of which it is parallel.
The Internal Calcaneo-astragaloid Ligament (ligamentum talocalcaneum mediate)
is a band of fibres connecting the internal tubercle of the back of the astragalus
with the back of the sustentaculum tali. Its fibres blend with those of the inferior
calcaneo-scaphoid ligament.
The Anterior Calcaneo-astragaloid Ligament (ligamentum talocalcaneum anterius)
passes from the front and outer surface of the neck of the astragalus to the supe-
rior surface of the os calcis.
The Posterior Calcaneo-astragaloid Ligament (ligamentum talocalcaneum posterius)
connects the external tubercle of the astragalus with the upper and inner part
of the os calcis ; it is a short band, the fibres of which radiate from their narrow
attachment to the astragalus.
The Interosseous Ligament (ligamentum talocalcaneum interosseum) (Figs. 250,
251, and 255) forms the chief bond of union between the bones. It consists of
numerous vertical and oblique fibres attached by one extremity to the groove
between the articulating facets on the under surface of the astragalus; by the
other to a corresponding depression on the upper surface of the os calcis. It
is very thick and strong, being at least an inch in breadth from side to side,
and serves to unite the os calcis and astragalus solidly together.
Synovial Membrane. — The synovial membranes (Fig. 255) are two in num-
ber: one for the posterior calcaneo-astragaloid articulation; a second for the
anterior calcaneo-astragaloid joint. The latter synovial membrane is con-
tinued forward between the contiguous surfaces of the astragalus and scaphoid
bones.
ARTICULATIONS OF THE TARSUS 355
Actions. — The movements permitted between the astragalus and os calcis are
limited to a gliding of the one bone on the other in a direction from before back-
ward, and from side to side.
2. ARTICULATION OF THE Os CALCIS WITH THE CUBOID OR THE CALCANEO-
CUBOID ARTICULATION (ARTICULATIO CALCANEOCUBOIDEA) (Fig. 251).
In this joint the articular capsule (capsula articularis) is strengthened at
certain points by definite ligaments.
The ligaments connecting the os calcis with the cuboid are four in number:
Dorsal or Superior Calcaneo-cuboid. „ p. ( Long Calcaneo-cuboid.
The Internal Calcaneo-cuboid. T\ Short Calcaneo-cuboid.
The Superior Calcaneo-cuboid Ligament (ligamentum calcaneocuboideum dorsale)
(Fig. 252) is a broad portion of the capsule which passes between the contiguous
surfaces of the os calcis and cuboid on the dorsal surface of the joint.
The Internal Calcaneo-cuboid or the Interosseous Ligament (pars calcaneo-
cuboidea ligamenti bifurcati) is a short but thick and strong band of fibres
arising from the os calcis, in the deep hollow which intervenes between it and
the astragalus, and closely blended, at its origin, with the superior calcaneo-
scaphoid ligament. These two ligaments are often regarded as a single bifur-
cated ligament (ligamentum bifurcatum). The internal calcaneo-cuboid liga-
ment is inserted into the inner side of the cuboid bone. This ligament forms
one of the chief bonds of union between the first and second rows of the tarsus.
The Long Galcaneo-cuboid or Long Plantar or Superficial Long Plantar Ligament
(ligamentum plantar e longum) (Fig. 254), the more superficial of the two plantar
ligaments, is the longest of all the ligaments of the tarsus: it is attached to
the under surface of the os calcis, from near the tuberosities, as far forward as
the anterior tubercle; its fibres pass forward to be attached to the ridge on the
under surface of the cuboid bone, the more superficial fibres being continued
onward to the bases of the second, third, and fourth metatarsal bones. This
ligament crosses the groove on the under surface of the cuboid bone, converting
it into a canal for the passage of the tendon of the Peroneus longus.
The Short Calcaneo-cuboid or Short Plantar Ligament (ligamentum calcaneo-
cuboideum plantare) (Fig. 254) lies nearer the bones than the preceding, from
which it is separated by a little areolar tissue. It is exceedingly broad, about
an inch in length, and extends from the tubercle and the depression in front of
it, on the forepart of the under surface of the os calcis, to the inferior surface of
the cuboid bone behind the peroneal groove.
Synovial Membrane (Fig. 255). — The synovial membrane in this joint is distinct.
It lines the inner surface of the ligaments.
Actions. — The movements permitted between the os calcis and cuboid are
limited to a slight gliding upon each other.
3. THE LIGAMENTS CONNECTING THE Os CALCIS AND SCAPHOID OR THE
CALCANEO-SCAPHOID ARTICULATION LIGAMENTS.
Though these two bones do not directly articulate, they are connected together
by two ligaments:
Superior or External Calcaneo-scaphoid.
Inferior or Internal Calcaneo-scaphoid.
The Superior or External Calcaneo-scaphoid or Calcaneo-navicular (pars cal-
caneonavicularis ligamenti bifurcati) arises, as already mentioned, with the
internal calcaneo-cuboid in the deep hollow between the astragalus and os calcis,
356
THE ARTICULATIONS OR JOINTS
constituting a part of the ligamentum bifurcaturn ; it passes forward from the
upper surface of the anterior extremity of the os calcis to the outer side of the
scaphoid bone. These two ligaments resemble the letter Y, being blended together
behind, but separated in front.
The Inferior or Internal Calcaneo-scaphoid or Calcaneo-navicular (ligamentum
calcaneonavicidare plantare) (Fig. 254) is by far the larger and stronger of the two
ligaments between these bones; it is a broad and thick band of fibres, which
passes forward and inward from the anterior
margin of the sustentaculum tali of the os
calcis to the under surface of the scaphoid
bone. This ligament not only serves to
connect the os calcis and scaphoid, but sup-
ports the head of the astragalus, forming
part of the articular cavity in which it is
received. The upper surface presents a
fibro-cartilaginous facet, lined by the syn-
ovial membrane continued from the ante-
rior calcaneo-astragaloid articulation, upon
which a portion of the head of the astragalus
rests. Its under surface is in contact with
the tendon of the Tibialis posticus muscle;1
its inner border is blended with the forepart
of the Deltoid ligament, thus completing
the socket for the head of the astragalus.
Surgical Anatomy. — The inferior calcaneo-
scaphoid ligament, by supporting the head of the
astragalus, is principally concerned in maintaining
the arch of the foot, and when it yields the head of
the astragalus is pressed downward, inward, and
forward by the weight of the body, and the foot
becomes flattened, expanded, and turned outward,
constituting the disease known as flat-foot. This
ligament contains a considerable amount of elastic
fibre, so as to give elasticity to the arch and spring to
the foot; hence it is sometimes called the "spring"
ligament. It is supported, on its under surface, by
the tendon of the Tibialis posticus, which spreads
out at its insertion into a number of fasciculi which
are attached to most of the tarsal and metatarsal
bones; this prevents undue stretching of the ligament
and is a protection against the occurrence of flat-foot.
FIG. 254. — Ligaments of the plantar surface
of the foot.
4. ARTICULATION OF THE ASTRAGALUS WITH THE SCAPHOID BONE OR THE
ASTRAGALO-SCAPHOID ARTICULATION (ARTICULATI.O TALONAVICULARIS)
(Fig. 251).
The articulation between the astragalus and scaphoid is an arthrodial joint:
the rounded head of the astragalus being received into the concavity formed by
the posterior surface of the scaphoid, the anterior articulating surface of the
calcaneum, and the upper surface of the inferior calcaneo-scaphoid ligament,
which fills up the triangular interval between these bones. The only ligament of
this joint is the superior astragalo-scaphoid (Fig. 249). It is a broad band,
which passes obliquely forward from the neck of the astragalus to the superior
surface of the scaphoid bone. It is thin, and weak in texture, and covered by the
Extensor tendons. The inferior calcaneo-scaphoid ligament supplies the place of
an inferior astragalo-scaphoid ligament.
1 Mr. Hancock describes an extension of this ligament upward on the inner side of the foot, which com-
pletes the socket of the joint in that direction (Lancet, 1866, vol. i, p. 618). — ED. of 15th English Edition.
ARTICULATIONS OF THE TARSUS 357
Synovial Membrane (Fig. 255). — The synovial membrane which lines the joint
is continued forward from the anterior calcaneo-astragaloid articulation.
Actions. — This articulation permits of considerable mobility, but its feebleness
is such as to allow occasionally of dislocation of the other bones of the tarsus
from the astragalus.
The transverse tarsal or medio-tarsal joint (articulatio tarsi transversa [Choparti])
(Figs. 251 and 256) is formed by the articulation of the os calcis with the cuboid,
and by the articulation of the astragalus with the scaphoid. The movement which
takes place in this joint is more extensive than that in the other tarsal joints, and
consists of a sort of rotation by means of which the sole of the foot may be
slightly flexed and extended or carried inward (inverted) and outward (everted).
5. THE ARTICULATION OF THE SCAPHOID WITH THE CUNEIFORM BONES
(ARTICULATIO CUNEONAVICULARIS) (Fig. 251).
The scaphoid is connected to the three cuneiform bones by
Dorsal and Plantar ligaments.
The Dorsal Ligaments (ligamenta navicularicuneiformia dorsalia) (Figs. 249 and
251) are small, longitudinal bands of fibrous tissue arranged as three bundles, one
to each of the cuneiform bones. That bundle of fibres which connects the scaphoid
with the internal cuneiform is continued round the inner side of the articulation to
be continuous with the plantar ligament which connects these two bones.
The Plantar Ligaments (ligamenta navicularicuneiformia plantaria) (Fig. 254)
have a similar arrangement to those on the dorsum. They are strengthened by
processes given off from the tendon of the Tibialis posticus.
Synovial Membrane (Fig. 255). — The synovial membrane of these joints is
part of the great tarsal synovial membrane.
Actions. — The movements permitted between the scaphoid and cuneiform
bones are limited to a slight gliding upon each other.
6. THE ARTICULATION OF THE SCAPHOID WITH THE CUBOID (ARTICULATIO
CUBONAVICULARIS) .
The scaphoid bone is connected with the cuboid by
Dorsal, Plantar, and Interosseous ligaments.
The Dorsal Ligament (ligamentum cuboideonaviculare dor sale) (Fig. 252) con-
sists of a band of fibrous tissue which passes obliquely forward and outward
from the scaphoid to the cuboid bone.
The Plantar Ligament (ligamentum cuboideonaviculare plantare) consists of a
band of fibrous tissue which passes nearly transversely between these two bones.
The Interosseous Ligament (Figs. 251 and 255) consists of strong transverse
fibres which pass between the rough non-articular portions of the lateral sur-
faces of these two bones.
Synovial Membrane (Fig. 255). — The synovial membrane of this joint is part
of the great tarsal synovial membrane.
Actions. — The movements permitted between the scaphoid and cuboid bones
are limited to a slight gliding upon each other.
7. THE ARTICULATIONS OF THE CUNEIFORM BONES WITH EACH OTHER OR
THE INTERCUNEIFORM ARTICULATIONS (Fig. 251).
These bones are connected together by
Dorsal, Plantar, and Interosseous ligaments.
358
THE ARTICULATIONS OR JOINTS
The Dorsal Ligaments (ligamenta inter cuneiformia dorsalia) consist of two bands
of fibrous tissue which pass transversely, one connecting the internal with the
middle cuneiform, and the other connecting the middle with the external cunei-
form.
The Plantar Ligaments (ligamenta inter cuneiformia plantarid) have a similar
arrangement to those on the dorsum. They are strengthened by the processes
given off from the tendon of the Tibialis posticus.
The Interosseous Ligaments (ligamenta inter cuneiformia interossea) consist of
strong transverse fibres which pass between the rough non-articular portions of
the lateral surfaces of the first and second and the second and third cuneiform
bones. The outer portion of the third cuneiform is attached to the cuboid by
the ligamentum cuneocuboideum, interosseum.
Synovial Membrane (Fig. 255). — The synovial membrane of these joints is part
of the great tarsal synovial membrane.
Actions. — The movements permitted between the cuneiform bones are limited
to a slight gliding upon each other.
8. THE ARTICULATION OF THE EXTERNAL CUNEIFORM BONE WITH THE
CUBOID (Fig. 251).
These bones are connected together by
Dorsal, Plantar, and Interosseous ligaments.
The Dorsal Ligament (ligamentum cuneocuboideum dorsale) (Fig. 252) consists
of a band of fibrous tissue which passes transversely between these two bones.
The Plantar Ligament (ligamentum cuneocuboideum plantare) has a similar
arrangement. It is strengthened by a process given off from the tendon of the
Tibialis posticus.
The Interosseous Ligament (ligamentum cuneocuboideum interosseum) (Fig. 251)
consists of strong transverse fibres which pass between the rough non-articular
portions of the lateral surfaces of the adjacent sides of these two bones.
Synovial Membrane (Fig. 255). — The synovial membrane of this joint is part
of the great tarsal synovial membrane.
Actions. — The movements permitted between the external cuneiform and
cuboid are limited to a slight gliding upon each other.
Nerve-supply.— All the joints of the tarsus are supplied by the anterior tibial
nerve.
Surgical Anatomy. — In spite of the great strength of the ligaments which connect the tarsal
bones together, dislocation at some of the tarsal joints does occasionally occur; though, on
account of the spongy character of the bones, they are more frequently broken than dislocated,
as the result of violence. When dislocation does occur, it is most commonly in connection with
the astragalus; for not only may this bone be dislocated from the tibia and fibula at the ankle-
joint, but the other bones may be dislocated from it, the trochlear surface of the bone remaining
in situ in the tibio-fibular mortise. This constitutes what is known as the subastragaloid dis-
location. Or, again, the astragalus may be dislocated from all its connections — from the tibia
and fibula above, the os calcis below, and the scaphoid in front — and may even undergo a
rotation, either on a vertical or horizontal axis. In the former case the long axis of the bone
becoming directed across the joint, so that the head faces the articular surface on one or other
malleolus; or, in the latter, the lateral surfaces becoming directed upward and downward, so
that the trochlear surface faces to one or the other side. Finally, dislocation may occur at
the medio-tarsal joint, the anterior tarsal bones being luxated from the astragalus and cal-
caneum. The other tarsal bones are also, occasionally, though rarely, dislocated from their
connections.
Pes planus, flat-foot, or splay-foot is a condition in which there is abduction, eversion, and
loss of both the longitudinal and the transverse arch. The head of the astragalus passes down-
ward and inward ; the anterior portion of the foot is turned outward and the inner side of the
foot is lengthened and broadened. Deformity is increased when standing. In severe cases
TARSO - METATARSAL ARTICULATIONS 359
the patient walks on the inner side of the foot. The condition is due to yielding of the tarsal
ligaments. Abduction is permitted by yielding of the internal lateral and calcaneo-astragaloid
ligaments. Yielding of the calcaneo-scaphoid ligament permits the head of the astragalus to pass
downward and forward, and the entire arch falls. Further deformity is induced by the yielding
of the ligaments.
VI. Tarso-metatarsal Articulations (Articulationes Tarsometatarseae
[Lisfranci]) (Figs. 249, 251, 252, 254, 257).
These are arthrodial joints. The bones entering into their formation are four
tarsal hones — viz., the internal, middle, and external cuneiform and the cuboid —
which articulate with the metatarsal bones of the five toes. The metatarsal bone
of the great toe articulates with the internal cuneiform; that of the second is
deeply wedged in between the internal and external cuneiform, resting against the
middle cuneiform, and being the most strongly articulated of all the metatarsal
bones; the third metatarsal articulates with the extremity of the external cunei-
form; the fourth, with the cuboid and external cuneiform; and the fifth, with
the cuboid. The articular surfaces are covered with cartilage, lined by
synovial membrane, and connected together by capsules and by the following
ligaments :
Dorsal. Plantar. Interosseous.
The Dorsal Ligaments (ligamenta tarsometatarsea dorsalia) consist of strong,
flat, fibrous bands, which connect the tarsal with the metatarsal bones. The
first metatarsal is connected to the internal cuneiform by a single broad, thin,
fibrous band; the second has three dorsal ligaments, one from each cuneiform
bone; the third has one from the external cuneiform; the fourth has two, one
from the external cuneiform and one from the cuboid; and the fifth, one from
the cuboid.
The Plantar Ligaments (ligamenta tarsometatarsea plantaria) consist of longi-
tudinal and oblique fibrous bands connecting the tarsal and metatarsal bones,
but disposed with less regularity than on the dorsal surface. Those for the first
and second metatarsal are the most strongly marked; the second and third meta-
tarsal receive strong fibrous bands which pass obliquely across from the internal
cuneiform; the plantar ligaments of the fourth and fifth metatarsal consist of a
few scanty fibres derived from the cuboid.
The Interosseous Ligaments (ligamenta cuneometatarsea interossea) are three in
number — internal, middle, and external. The internal one is the strongest of the
three, and passes from the outer extremity of the internal cuneiform to the
adjacent angle of the second metatarsal. The middle one, less strong than the
preceding, connects the external cuneiform with the adjacent angle of the second
metatarsal. The external interosseous ligament connects the outer angle of the
external cuneiform with the adjacent side of the third metatarsal.
Synovial Membrane (Fig. 255). — The synovial membrane between the internal
cuneiform bone and the first metatarsal bone is a distinct sac. The synovial
membrane between the middle and external cuneiform behind, and the second
and third metatarsal bones in front, is part of the great tarsal synovial membrane.
Two prolongations are sent forward from it — one between the adjacent sides of
the second and third metatarsal bones, and one between the third and fourth
metatarsal bones. The synovial membrane between the cuboid and the fourth
and fifth metatarsal bones is a distinct sac. From it a prolongation is sent for-
ward between the fourth and fifth metatarsal bones.
Actions. — The movements permitted between the tarsal and metatarsal bones
are limited to a slight gliding upon each other.
360 THE ARTICULATIONS OR JOINTS
VII. Articulations of the Metatarsal Bones with Each Other
(Articulationes Intermetatarseae) (Figs. 251, 252, 254).
The base of the first metatarsal bone is not connected with the second meta-
tarsal bone by any ligaments; in this respect it resembles the thumb.
The bases of the four outer metatarsal bones are connected together by dorsal,
plantar, and interosseous ligaments.
The Dorsal Ligaments (ligamenta basium [oss. metatars.] dorsalia) consist of
bands of fibrous tissue which pass transversely between the adjacent metatarsal
bones.
The Plantar Ligaments (ligamenta basium [oss. metatars,] plantaria) have a
similar arrangement to those on the dorsum.
The Interosseous Ligaments (ligamenta basium [oss. metatars.] interossea) con-
sist of strong transverse fibres which pass between the rough non-articular portions
of the lateral surfaces.
Synovial Membrane. — The synovial membrane between the second and third
and the third and fourth metatarsal bones is part of the great tarsal synovial mem-
brane. The synovial membrane between the fourth and fifth metatarsal bones is
a prolongation of the synovial membrane of the cubo-metatarsal joint (Fig. 255) .
Actions. — The movement permitted in the tarsal ends of the metatarsal boneS
is limited to a slight gliding of the articular surfaces upon one another.
THE SYNOVIAL MEMBRANES IN THE TARSAL AND METATARSAL JOINTS.
The synovial membranes (Fig. 255) found in the articulations of the tarsus
and metatarsus are six in number; one for the posterior calcaneo-astragaloid
FIG. 255. — Oblique section of the articulations of the tarsus and metatarsus. Showing the six synovial
membranes.
articulation; a second for the anterior calcaneo-astragaloid and astragalo-
scaphoid articulations; a third for the calcaneo-cuboid articulation; and a fourth
for the articulations of the scaphoid with the three cuneiform, the three cunei-
form with each other, the external cuneiform with the cuboid, and the middle and
external cuneiform with the bases of the second and third metatarsal bones, and
the lateral surfaces of the second, third, and fourth metatarsal bones with each
other; a fifth for the internal cuneiform with the metatarsal bone of the great toe;
and a sixth for the articulation of the cuboid with the fourth and fifth metatarsal
bones. A small synovial membrane is sometimes found between the contiguous
surfaces of the scaphoid and cuboid bones.
ARTICULATIONS OF THE PHALANGES 361
Nerve-supply. — The nerves supplying the tarso-metatarsal joints are derived
from the anterior tibial.
The digital extremities of all the metatarsal bones are connected together by
the transverse metatarsal ligament.
The Transverse Metatarsal Ligament is a narrow fibrous band which passes
transversely across the anterior extremities of all the metatarsal bones, connecting
them together. It is blended anteriorly with the plantar (glenoid} ligament of
each metatarso-phalangeal articulation. To its posterior border is connected the
fascia covering the Interossei muscles. Its inferior surface is concave where the
Flexor tendons pass over it. Above it the tendons of the Interossei muscles pass
to their insertion. It differs from the transverse metacarpal ligament in that it
connects the metatarsal bone of the great toe with the rest of the metatarsal bones.
VIII. Metatarso-phalangeal Articulations (Articulationes Metatarso-
phalangeae).
The metatarso-phalangeal articulations are of the condyloid kind, formed by
the reception of the rounded head of the metatarsal bone into a superficial cavity
in the extremity of the first phalanx. Each joint has a capsule and certain
other ligaments.
These ligaments are —
Plantar. Two Lateral.
The Plantar Ligaments or the Glenoid Ligaments of Cruveilhier (ligamenta
accessoria plantaria) are thick, dense, fibrous structures. Each is placed on
the plantar surface of the joint in the interval between the lateral ligaments,
to which it is connected. The plantar ligaments are loosely united to the meta-
tarsal bones, but very firmly to the bases of the first phalanges. The plantar
surface of each is intimately blended with the transverse metatarsal ligament,
and, except in the great toe, presents a groove for the passage of the Flexor
tendons, the sheath surrounding which is connected^ to each side of the groove.
The plantar ligament of the great toe contains two large sesamoid hones. By
their deep surface they form part of the articular surface for the head of the
metatarsal bone, and are lined by synovial membrane.
The Lateral Ligaments (ligamenta collateralia) are strong, rounded cords, placed
one on each side of the joint, each being attached, by one extremity, to the poste-
rior tubercle on the side of the head of the metatarsal bone; and, by the other, to
the contiguous extremity of the phalanx.
The place of a Posterior Ligament is supplied by the extensor tendon over the
back of the joint.
Actions. — The movements permitted in the metatarso-phalangeal articulations
are flexion, extension, abduction, and adduction.
IX. Articulations of the Phalanges (Articulationes Digitorum Pedis).
The articulations of the phalanges are ginglymoid joints. Besides the cap-
sular the ligaments are —
Plantar. Two Lateral (ligamenta collateralia).
The arrangement of these ligaments is similar to those in the metatarso-phalan-
geal articulations; the extensor tendon supplies the place of a posterior ligament.
Actions. — The only movements permitted in the phalangeal joints are flexion
and extension; these movements are more extensive between the first and second
phalanges than between the second and third. The movement of flexion is very
considerable, but extension is limited by the plantar and lateral ligaments.
362
THE ARTICULATIONS OR JOINTS
Surface Form. — The principal joints which it is necessary to distinguish, with regard to
the surgery of the foot, are the medio-tarsal and the tarso-metatarsal. The joint between the
astragalus and the scaphoid is best found by means of the tubercle of the scaphoid, for
the line of the joint is immediately behind this process. If the foot is grasped and forcibly
extended, a rounded prominence, the head of the astragalus, will appear on the inner side of
the dorsum in front of the ankle-joint, and if a knife is carried downward, just in front of this
prominence and behind the line of the scaphoid tubercle, it will enter the astragalo-scaphoid
joint. The calcaneo-cuboid joint is situated midway between the external malleolus and the
prominent end of the fifth metatarsal bone. The plane of the joint is in the same line as that
of the astragalo-scaphoid. The position of the joint between the fifth metatarsal bone and the
cuboid is easily found by the projection of the fifth metatarsal bone, which is the guide to it.
The direction of the line of the joint is very oblique, so that, if continued onward, it would
pass through the head of the first metatarsal bone. The joint between the fourth metatarsal
bone and the cuboid and external cuneiform is the direct continuation inward of the previous
joint, but its plane is less oblique; it would be represented by a line drawn from the outer side
of the articulation to the middle of the first metatarsal bone. The plane of the joint between
the third metatarsal bone and the external cuneiform is almost transverse. It would be repre-
CALCANEUS
FIFTH-f-
METATARSAL
EXTERNAL
CUNEIFORM
FIRST
METATARSAL
FIG. 256. — Line of Chopart's amputation.
(Poirier.)
FIG. 257.— Line of Lisfranc's amputation.
(Poirier.)
sented by a line drawn from the outer side of the joint to the base of the first metatarsal bone.
The tarso-metatarsal articulation of the great toe corresponds to a groove which can be felt by
making firm pressure on the inner side of the foot one inch in front of the tubercle on the
scaphoid bone; and the joint between the second metatarsal bone and the middle cuneiform is
to be found on the dorsum of the foot, half an inch behind the level of the tarso-metatarsal joint
of the great toe. The line of the joints between the metatarsal bones and the first phalanges
is about an inch behind the webs of the corresponding toes.
Surgical Anatomy. — Chopart's amputation passes through the middle tarsal joint (astragalo-
scaphoid and calcaneo-cuboid articulation). Fig. 256 shows the line of Chopart. Lisfranc
amputated at the tarso-metatarsal articulation. Fig. 257 shows the line of Lisfranc. In Key's
amputation the fifth, fourth, third, and second metatarsal bones are disarticulated from the
tarsus and the internal cuneiform is sawn through. In the operation of Forbes, of Toledo, the
cuneiform bones are disarticulated from the scaphoid, the cuboid is sawn through on a line
with the surface exposed by the disarticulation.
THE MUSCLES AND FASCLE.1
MYOLOGY is the branch of anatomy which treats of the muscles. The
muscles are formed of bundles of reddish fibres, endowed notably with the
property of contractility in the direction of the long axes of the muscle cells.
Contractions of muscle fibres induce motion. The two principal kinds of muscu-
lar tissue found in the body are the more highly differentiated, or voluntary, and
the less highly differentiated, or involuntary. The former of these, from the char-
acteristic appearances which its fibres exhibit under the microscope, is known as
striated or striped muscle. Striped muscle is called voluntary because of the fact
that it is capable of being put into action and controlled by the will. The fibres
of involuntary muscle do not present any cross-striped appearance, and for the
most part are not under the control of the will ; such muscles are known as unstri-
ated, unstriped or vegetative. The muscular fibres of the heart differ in certain
particulars from both these groups, and they are therefore separately described
as cardiac muscular fibres.
Thus it will be seen that there are three varieties of muscular fibres: (1) Trans-
versely striated muscular fibres, which are for the most part voluntary and under
the control of the will, but some of which are not so (for example, the muscles of
the pharynx and upper part of the resophagus). This variety of muscle is some-
times called skeletal. (2) Transversely striated muscular fibres, which are not
under the control of the will — -i. e., the cardiac muscles. The cardiac muscle
occupies a midposition in the scale between the cells of involuntary and the striated
fibres of voluntary muscle. (3) Plain or unstriped muscular fibres, which are
involuntary and controlled by a different part of the nervous system from that
which controls the activity of the voluntary muscles. Such are the muscular walls
of the stomach and intestine, of the uterus and bladder, of the blood-vessels, of
certain canals and ducts, etc. The statement that striated muscle is always vol-
untary, and that non-striated muscle is always involuntary cannot be accepted as
invariably and inevitably true. There are animals in which some voluntary
muscle is free from distinct striation.
In this section we treat of the skeletal or striated muscles only. The skeletal
muscles act upon the bones, and thus produce movement. The primitive con-
tractile elements of a muscle are the fibres. Fibres are gathered into groups
known as fasciculi, and fasciculi are aggregated into masses called bundles. In
coarse muscles the fasciculi are of considerable size; in fine muscles they are of
trivial size. Fasciculi may be long or short, and the length does not depend on the
length of the muscle. If a muscle has an insertion only at each end, the fasciculi
are sure to be long and may reach from the tendon of origin to the tendon of
1 The Muscles and Fascise are described conjointly, in order that the student may consider the arrangement
of the latter in his dissection of the former. It is rare for the student of anatomy in this country to have
the opportunity of dissecting the fasciae separately; and it is for this reason, as well as from the close con-
nection that exists between the muscles and their investing sheaths, that they are considered together. Some
general observations are first made on the histology and anatomy of the muscles and fasciae, the special
description being given in connection with the different regions.
(363 )
364 THE MUSCLES AND FASCIAE
insertion. If a muscle takes attachments to the side or to septa within the muscle,
the fasciculi may be very short even when the muscle is very long.
Structure of Striated Muscle. — The striated muscle fibre is a development of
a muscle cell. Each cell is long and narrow and is called a fibre, and by shorten-
ing of these fibres the muscle, as a whole, is shortened.
A fibre is more or less cylindrical in outline, is usually spindle-shaped, and in
some regions the fibres branch. The diameter is very variable, and does not depend
in any degree upon the size of the muscle, and in the same muscle are found fibres
varying widely in diameter. As a rule, the diameter varies between 0.01 and
0.1 mm.
The fibres are usually short, being seldom over 5 cm. in length. In some muscles,
as in the Sartorius, they are much longer, and may be 10 or 12 cm. in length. Some-
times a fibre extends the entire length of a small muscle. A muscle fibre is surrounded
by a sheath or wall, the sarcolemma. Muscle fibres are gathered into masses known
as primary bundles, which are held to each other by scanty connective tissue
called the endomysium. Each primary bundle is surrounded by the perimysium.
Primary bundles are aggregated into groups, the secondary bundles, and each
secondary bundle is invested by the epimysium which is derived from the muscle
sheath.
Structure of the Muscle Fibre. — The muscle fibre is an elongated cell containing
numerous nuclei and terminating by blending of the sarcolemma with tendon
aponeurosis or fibrous septum, or else, after becoming rounded or tapering, joining
another cell by fusion of the sarcolemma of both. The sarcolemma completely
invests the muscle fibre and attaches the fibre to tendon, aponeurosis, or the sar-
colemma of another fibre, as the case may be.
The muscular substance within the sheath of sarcolemma is composed of pro-
toplasm. One part is unchanged protoplasm, and is called sarcoplasm. This con-
tains the muscle nuclei. Another part is highly differentiated; it contains the
contractile fibrillse and is striated. Transverse striation is due to alteration in the
parts of the fibre, so that the altered material has a different refractive index and
stains differently from the unaltered portions of the fibre. In man most muscles
are of the red type, but some (mixed muscles) contain red and white fibres. A red
muscle fibre contains a considerable quantity of sarcoplasm, and the nuclei are
toward the centre of the cell; in a white muscle fibre there is less sarcoplasm, the
nuclei are toward the periphery, and striation is very distinct.1
The Arteries of voluntary muscle are numerous. They pierce the epimysium,
pass along the septa from the epimysium, and divide into small branches, which
enter between the fasciculi. These small branches pass into capillaries which lie
around the fibres. The capillaries form a network between and upon the fibres.
Capillary plexuses here and there possess dilatations for the relief of tension during
muscular action.
Veins accompany the arteries, and even the smaller ones possess valves
(Spalteholz).
The Nerve Endings in voluntary muscle comprise both motor and sensory ter-
minations. A motor nerve pierces the epimysium and breaks up into numerous
branches to form an interfascicular plexus in the perimysium. From this plexus
nerve fibrils arise and usually one nerve fibril passes to each muscle fibre. The
nerve fibril pierces the sarcolemma, the neurilemma and medullary sheath dis-
appearing before the nerve fibril reaches the muscle fibre, and probably being
lost by fusing with the sarcolemma. The naked axis-cylinder beneath the sar-
colemma of a fibre continues to the surface of the muscle fibre and undergoes
arborization to form an end organ. Around the end organ is a quantity of granular
'•A Text-book of Histology. By Dr. Ladislaus Szymonowicz. Translated and edited by Dr. John Bruce
MacCallum.
THE STRUCTURE OF MUSCLE 365
sarcoplasm, which, with the nerve end organ, constitutes a sole-plate. A sensory
nerve takes origin from a muscle spindle, which consists of a bundle of encapsuled
muscle fibre about sensory nerve twigs. From a muscle spindle arise from two to
eight large myelinic nerve fibres.
The muscles are connected with the bones, cartilages, ligaments, and skin,
either directly or through the intervention of fibrous structures called tendons
or aponeuroses. Where a muscle is attached to bone or cartilage, the fibres ter-
minate in blunt extremities upon the periosteum or perichondrium, and do not
come into direct relation with the osseous or cartilaginous tissue. Where muscles
are connected with the skin, they either lie as a flattened layer beneath it, or are
connected with its areolar tissue by larger or smaller bundles of fibres, as in the
muscles of the face. The direct continuation of the tendon of a muscle is known
as the belly or venter. The origin of a muscle is its head (caput).
The muscles vary extremely in their form. In the limbs they are of consid-
erable length, especially the more superficial ones, the deep ones being generally
broad; they surround the bones and form an important protection to the various
joints. In the trunk they are broad, flattened, and expanded, forming the parietes
of the cavities which they enclose; hence the reason of the terms long, broad,
short, etc., used in the description of a muscle.
There is a considerable variation in the arrangement of the fibres of certain
muscles with reference to the tendons to which they are attached. In some, the
fibres are parallel and run directly from their origin to their insertion; these are
quadrilateral muscles, such as the Thyro-hyoid. A modification of these is found in
the fusiform muscles (m. fusiformis) , in which the fibres are not quite parallel, but
slightly curved, so that the muscle tapers at each end; in their action, however, they
resemble the quadrilateral muscles. Secondly, in other muscles the fibres are con-
vergent; arising by a broad origin, they converge to a narrower pointed insertion.
This arrangement of fibres is found in the triangular muscles — e. g., the Temporal.
In some muscles, which otherwise would belong to the quadrilateral or triangular
type, the origin and insertion are not in the same plane, but the plane of the line
of origin intersects that of their insertion ; such is the case in the Pectineus muscle.
Thirdly, in some muscles the fibres are oblique and converge, like the plumes
of a pen, to one side of a tendon, which runs the entire length of the muscle.
Such a muscle is rhomboidal or penniform (m. unipennatus) , as the Peronei. A
modification of these rhomboidal muscles is found in those cases where oblique
fibres convero-e to both sides of a central tendon which runs down the middle of
O
the muscle ; these are called bipenniform (m. bipennatiis) , and an example is afforded
MI the Rectus femoris. Finally, we have muscles in which the fibres are arranged
in curved bundles in one or more planes, as in an orbicular muscle (m. orbicularis)
and in that variety of orbicular muscle called a sphincter muscle (m. sphincter).
The arrangement of the muscular fibres is of considerable importance in respect
to their relative strength and range of movement. Those muscles where the
fibres are long and few in number have great range, but diminished strength;
where, on the other hand, the fibres are short and more numerous, there is
great power, but lessened range.
Muscles differ much in size: the Gastrocnemius forms the chief bulk of the
back of the leg; the Sartorius is very long; the Stapedius, a small muscle of the
internal ear, weighs about a grain, and its fibres are not more than two lines in
length.
The names applied to the various muscles have been derived — 1, from their
situation, as the Tibialis, Radialis, Ulnaris, Peroneus; 2, from their direction, as
the Rectus abdominis, Obliquus capitis,Transversalis; 3, from their uses, as Flexors,
Extensors, Abductors, etc.; 4, from their shape, as the Deltoid, Trapezius, Rhom-
boideus; 5, from the number of their divisions, as the Biceps, the Triceps; 6,
366 THE MUSCLES AND FASCIAE
from their points of attachment, as the Sterno-cleido-mastoid, Sterno-hyoid,
Sterno-thyroid.
In the description of a muscle the term origin is meant to imply its more fixed
or central attachment, and the term insertion, the movable point to which the
force of the muscle is directed; but the origin is absolutely fixed in only a very
small number of muscles, such as those of the face, which are attached by one
extremity to the bone and by the other to the movable integument; the greater
number of muscles can be made to act from either extremity.
In the dissection of the muscles the student should pay especial attention to
the exact origin, insertion, and actions of each, and its more important relations
with surrounding parts. An accurate knowledge of the points of attachment of
the muscles is of great importance in the determination of their action. By a
knowledge of the action of the muscles the surgeon is able to explain the causes
of displacement in various forms of fracture and the causes which produce dis-
tortion in various deformities, and, consequently, to adopt appropriate treatment
in each case. The relations, also, of some of the muscles, especially those in
immediate apposition with the larger blood-vessels, and the surface-markings they
produce, should be especially remembered, as they form useful guides to the
surgeon who operates to expose and ligate them.
Tendons. — Tendons are white, glistening, fibrous cords, varying in length and
thickness, sometimes round, sometimes flattened, of considerable strength, and
devoid of elasticity. They consist almost entirely of white fibrous tissue., the fibrils
of which have an undulating course parallel with each other and are firmly united
together. They are very sparingly supplied with blood-vessels, the smaller ten-
dons presenting in their interior not a trace of them. Nerves also are not present
in the smaller tendons, but the larger ones, as the tendo Achillis, receive nerves
which accompany nutrient vessels. The tendons consist principally of a sub-
stance which yields gelatin.
Aponeuroses. — Aponeuroses are flattened or ribbon-shaped tendons, of a
pearly-white color, iridescent, glistening, and similar in structure to the tendons.
They are destitute of nerves, and the thicker ones are only sparingly supplied
with blood-vessels.
The tendons and aponeuroses are connected, on the one hand, with the mus-
cles, and, on the other hand, with movable structures, as the bones, cartilages,
ligaments, fibrous membranes (for instance, the sclerotic). Where the muscular
fibres are in a direct line with those of the tendon or aponeurosis, the two are
directly continuous, the muscular fibre being distinguishable from that of the
tendon only by its striation. But where the muscular fibres join the tendon or
aponeurosis at an oblique angle the former terminate, according to Kolliker, in
rounded extremities, which are received into corresponding depressions on the
surface of the latter, the connective tissue between the fibres being continuous
with that of the tendon. The latter mode of attachment occurs in all the penni-
form and bipenniform muscles, and in those muscles the tendons of which com-
mence in a membranous form, as the Gastrocnemius and Soleus.
Fasciae. — The fasciae (fascia, a bandage) are fibro-areolar or aponeurotic
laminae of variable thickness and strength, found in all regions of the body,
investing the softer and more delicate organs. The fascia have been sub-
divided, from the situation in which they are found, into two groups, superficial
and deep.
Superficial Fascia (panniculus adiposus}. — The superficial fascia is found imme-
diately beneath the integument over almost the entire surface of the body. It
connects the skin with the deep or aponeurotic fascia, and consists of fibro-areolar
tissue, containing in its meshes pellicles of fat in varying quantity. In the eyelids
and scrotum, where adipose tissue is rarely deposited, this tissue is very liable to
MUSCLES AND FASCIA OF THE CRANIUM AND FACE 367
serous inflammation. The superficial fascia varies in thickness in different parts
of the body: in the groin it is so thick as to be capable of being subdivided in
several lamina*. Beneath the' fatty layer of the superficial fascia, which is imme-
diately subcutaneous, there is generally another layer of the same structure, com-
paratively devoid of adipose tissue, in which the trunks of the subcutaneous vessels
and nerves are found, as the superficial epigastric vessels in the abdominal region,
the radial and ulnar veins in the forearm, the saphenous veins in the leg and
thigh, and the superficial lymphatic glands; certain cutaneous muscles also are
situated in the superficial fascia, as the Platysma myoides in the neck, and the
Orbicularis palpebrarum around the eyelids. This fascia is most distinct at the
lower part of the abdomen, the scrotum, perinaeum, and extremities; is very thin
in those regions where muscular fibres are inserted into the integument, as on
the side of the neck, the face, and around the margin of the anus. It is very
dense in the scalp, in the palms of the hands and soles of the feet, forming a fibro-
fatty layer which binds the integument firmly to the subjacent structure. The
superficial fascia connects the skin to the subjacent parts, facilitates the move-
ment of the skin, serves as a soft medium for the passage of vessels and nerves
to the integument, and retains the warmth of the body, since the fat contained in
its areolse is a bad conductor of heat.
Deep Fascia. — The deep or aponeurotic fascia is a dense, inelastic, unyielding
fibrous membrane, forming sheaths for the muscles and affording them broad
surfaces for attachment. It consists of shining tendinous fibres, placed parallel
with one another, and connected together by other fibres disposed in a rectilinear
manner. It is usually exposed on the removal of the superficial fascia, forming a
strong investment, which not only binds down collectively the muscles in each
region, but gives a separate sheath to each, as well as to the vessels and nerves.
The fasciae are thick in unprotected situations, as on the outer side of a limb, and
thinner on the inner side. The deep fasciae assist the muscles in their action by
the degree of tension and pressure they make upon their surface; and in certain
situations this is increased and regulated by muscular action; as, for instance, by
the Tensor fasciae femoris and Gluteus maximus in the thigh, by the Biceps in
the upper and lower extremities, and Palmaris longus in the hand. In the limbs
the fasciae not only invest the entire limb, but give off septa which separate the
various muscles, and are attached beneath to the periosteum : these prolongations
of fasciae are usually spoken of as intermuscular septa.
The Muscles and Fasciae may be arranged, according to the general division
of the body, into those of the cranium, face, and neck; those of the trunk; those of
the upper extremity; and those of the lower extremity.
MUSCLES AND FASCLffl OF THE CRANIUM AND FACE.
The muscles of the cranium and face consist of ten groups, arranged according
to the region in which they are situated:
1. Cranial Region. 6. Maxillary Region.
2. Auricular Region. 7. Mandibular Region.
3. Palpebral Region. 8. Intermaxillary Region.
4. Orbital Region. 9. Temporo-mandibular. Region.
5. Nasal Region 10. Pterygo-mandibular Region.
368
THE MUSCLES AND FASCIA
The muscles contained in each of these groups are the following:
1. Cranial Region.
Occipito-frontalis.
2. Auricular Region.
Attrahens auriculam.
Attollens auriculam.
Retrahens auriculam.
3. Palpebral Region.
Orbicularis palpebrarum.
Corrugator supercilii.
Tensor tarsi.
4. Orbital Region.
Levator palpebrse.
Rectus superior.
Rectus inferior.
Rectus internus.
Rectus externus.
Obliquus superior.
Obliquus inferior.
5. Nasal Region.
Pyramidalis nasi.
Levator labii superioris alseque
nasi.
Dilator naris posterior.
Dilator naris anterior.
Compressor nasi.
Compressor narium minor.
Depressor alre nasi.
6. Maxillary Region.
Levator labii superioris.
Levator anguli oris.
Zygomaticus major.
Zygomaticus minor.
7. Mandibular Region.
Levator labii inferioris.
Depressor labii inferioris.
Depressor anguli oris.
8. Intermaxillary Region.
Buccinator.
Risorius.
Orbicularis oris.
9. Temporo-mandibular Region.
Masseter.
Temporal.
10. Pterygo-mandibular Region.
Pterygoideus externus.
Pterygoideus internus.
1. The Cranial Region.
Occipito-frontalis.
Dissection (Fig. 258). — The head being shaved, and a block placed beneath the back of
the neck, make a vertical incision through the skin from before backward, commencing at
the root of the nose in front, and terminating behind at the occipital protuberance; make a
second incision in a horizontal direction along the forehead and round the side of the head,
from the anterior to the posterior extremity of the preceding. Raise the skin in front, from
the subjacent muscle, from below upward; this must be done with extreme care, removing
the integument from the outer surface of the vessels and the nerves which lie immediately
beneath the skin.
The Skin of the Scalp. — This is thicker than in any other part of the body. It
is intimately adherent to the superficial fascia, which attaches it firmly to the
underlying aponeurosis and muscle. Movements of the muscle move the skin.
The hair-follicles are very closely set together, and extend throughout the whole
thickness of the skin. It also contains a number of sebaceous glands.
Superficial Fascia. — The superficial fascia in the cranial region is a firm,
dense, fibro-fatty layer, intimately adherent to the integument, and to the occipito-
frontalis and its tendinous aponeurosis; it is continuous, behind, with the super-
ficial fascia at the back part of the neck; and, laterally, is continued over the
temporal fascia. It contains between its layers the superficial vessels and nerves
and much granular fat.
THE CRANIAL REGION
369
Surgical Anatomy.— The subcutaneous tissue is composed of bands of fibrous tissue enclos-
ing spaces filled with fat. The fibrous character of this tissue greatly limits discoloration and
swelling when inflammation occurs. The edges of a wound which does not involve the apon-
eurosis or muscle do not retract, hence the wound does not gap. The blood-vessels run practi-
cally in the skin, and as they lie in very dense tissue and are adherent to it, wounds bleed
profusely, the arteries being unable to freely contract and retract. It is very difficult or
impossible to pick up with forceps a vessel in the skin of the scalp, and bleeding must be
arrested by suture ligatures or by the stitches which close the wound. Sebaceous glands in
the skin of the scalp may develop into sebaceous cysts (wens).
1. Dissection of scalp.
3, 5, of auricular region.
4, 5, 6, of face.
7, 8, of neck.
FIG. 258. — Dissection of the head, face, and neck.
The Occipito-frontalis (m. epicranius) (Fig. 260). — The Occipito-frontalis
is a broad musculo-fibrous layer, which covers the whole of one side of the
SUBCUTANEOUS ADI-
SE TISSUE
APONEUROSIS OF
CCIPITO-FRONTALIS
MUSCLE
OCCIPITO-FRONTA
MUSCLE
BAPONEUROTIC
SSUE
ERIOSTEUM
OCCIPITO-FRONTALIS
MUSCLE
FIG. 259. — Epicrar.ial aponeurosis. Antero-posterior section. (Schematic.) (Poirier and Charpy.)
vertex of the skull, from the occiput to the eyebrow. It consists of two mus-
cular slips, separated by an intervening tendinous aponeurosis. The occipital
portion, the occipitalis muscle (m. occipitalis), is thin, quadrilateral in form, and
about an inch and a half in length; it arises from the outer two-thirds of the
superior curved line of the occipital bone, and from the mastoid portion of the
temporal bone. Its fibres of origin are tendinous, but they soon become muscular,
and ascend in a parallel direction to terminate in a tendinous aponeurosis. The
frontal portion, the frontalis muscle (m. frontalis), is thin, of a quadrilateral
form, and intimately adherent to the superficial fascia. It is broader, its fibres
are longer, and their structure paler than the occipital portion. Its internal
fibres are continuous with those of the Pyramidalis nasi. Some anatomists con-
24
370
THE MUSCLES AND FASCIA
sider the Pyramidalis muscle as simply the lower fibres of the frontalis, and
give these bundles of muscle fibre the name of musculus procerus. Its middle
fibres become blended with the Corrugator supercilii and Orbicularis palpebra-
rum ; and the outer fibres are also blended with the latter muscle over the external
angular process. According to Theile, the innermost fibres are attached to the
nasal bones, the outer to the external angular process of the frontal bone. From
these attachments the fibres are directed upward, and join the aponeurosis below
the coronal suture. The inner margins of the frontal portions of the two muscles
are joined together for some distance above the root of the nose; but between the
occipital portions there is a considerable, though variable, interval, which is occu-
pied by the aponeurosis.
The middle portion of the Occipito-frontalis muscle or the aponeurosis (epi-
cranial aponeurosis, Galea aponeurotica) covers the upper part of .the vertex
of the skull, being continuous across the middle line with the aponeurosis of the
CORRUGATOR SUPERCILII
DILATOR NAHIS ANTERIOR.
DILATOR NARIS POSTERIOR
COMPRESSOR NARIUM MINOR.
DEPRESSOR AL/t NASI.
LEVATOR MENTI.
FIG. 260. — Muscles of the head, face, and neck.
THE A URICULAR REGION 371
opposite muscle. Behind, it is attached, in the interval between the occipital
origins, to the occipital protuberance and highest curved lines of the occipital
bone; in front, it forms a short and narrow prolongation between the frontal por-
tions; and on each side it has connected with it the Attollens and Attrahens
auriculam muscles. This aponeurosis is closely connected to the integument by
the firm, dense, fibre-fatty layer which forms the superficial fascia; it is connected
with the pericranium by loose cellular tissue, which allows of a considerable
degree of movement of the integument. It is continuous with the temporal
fascia below the temporal ridge, and it is in reality the representative of the
deep fascia.
Nerves. — The frontal portion of the Occipito-frontalis is supplied by the facial
nerve; its occipital portion by the posterior auricular branch of the facial.
Actions. — The frontal portion of the muscle raises the eyebrows and the skin
over the root of the nose, and at the same time draws the scalp forward, throwing
the integument of the forehead into transverse wrinkles. The posterior portion
draws the scalp backward. By bringing alternately into action the frontal and
occipital portions the entire scalp may be moved forward and backward. In the
ordinary action of the muscles, the eyebrows are elevated, and at the same time
the aponeurosis is fixed by the posterior portion, thus giving to the face the
expression of surprise: if the action is more exaggerated, the eyebrows a're still
further raised, and the skin of the forehead thrown into transverse wrinkles, as in
the expression of fright or horror.
Surgical Anatomy. — The skull is covered by the scalp (Fig. 259). This consists of five layers:
(1) the pericranium; (2) a layer of connective tissue beneath the Occipito-frontalis aponeurosis
(subaponeurotic tissue); (3) the Occipito-frontalis muscle and aponeurosis; (4) subcutaneous fat;
(5) skin. If a wound involves the muscle or aponeurosis, it gaps widely, the greatest amount
of gaping being observed in transverse wounds. The space between the aponeurosis and the
pericranium is called by Treves the dangerous area of the scalp. It contains a layer of con-
nective tissue and suppuration in this tissue spreads widely. An abscess in the dangerous area
should be opened above the superior curved line of the occipital bone, above the eyebrow
or above the zygoma. In a wound or contusion above the aponeurosis but little blood can be,
effused in the tissue because the fibrous structure prevents it, and abscesses do not tend to
spread widely. Between the aponeurosis and the pericranium a great amount of blood can be
effused. An effusion of blood beneath the pericranium is called a cephalhoEmatoma. Such
a condition may occur from pressure during birth. An extravasation beneath the pericranium
is limited to the surface of one bone. The pericranium is tightly attached to the sutures, but
adheres lightly to the surface of the bone, and abscess beneath the pericranium is restricted
to the surface of one bone.
2. The Auricular Region (Fig. 260).
Attrahens auriculam. Attollens auriculam.
Retrahens auriculam.
These three small muscles are placed immediately beneath the skin around the
external ear. In man, in whom the external ear is almost immovable, they are
rudimentary. They are the analogues of large and important muscles in some
of the mammalia.
Dissection. — This requires considerable care, and should be performed in the following
manner: To expose the Attollens auriculam, draw the pinna, or broad part of the ear, downward,
when a tense band will be felt beneath the skin, passing from the side of the head to the upper
part of the concha; by dividing the skin over this band in a direction from below upward,
and then reflecting it on" each side, the muscle is exposed. To bring into view the Attrahens
auriculam, draw the helix backward by means of a hook, when the muscle will be made
tense, and may be exposed in a similar manner to the preceding. To expose the Retrahens
auriculam, draw the pinna forward, when the muscle, being made tense, may be felt beneath
the skin at its insertion into the back part of the concha, and may be exposed in the same
manner as the other muscles.
372 THE MUSCLES AND FASCIA
The Attrahens Auriculam or Aurem (m. auricularis anterior) , the smallest of the
three, is thin, fan-shaped, and its fibres pale and indistinct; they arise from the
lateral edge of the aponeurosis of the Occipito-frontalis, and converge to be inserted
into a projection on the front of the helix.
Relations. — Superficially, with the skin; deeply, with the areolar tissue derived
from the aponeurosis of the Occipito-frontalis, beneath which are the temporal
artery and vein and the temporal fascia.
The Attollens Auriculam or Aurem (m. auricularis superior), the largest of the
three, is thin and fan-shaped : its fibres arise from the aponeurosis of the Occipito-
frontalis and converge to be inserted by a thin, flattened tendon into the upper
part of the cranial surface of the pinna.
Relations. — Superficially, with the integument; deeply, with the areolar tissue
derived from the aponeurosis of the Occipito-frontalis, beneath which is the tem-
poral fascia.
The Retrahens Auriculam or Aurem (m. auricularis posterior) consists of two or
three fleshy fasciculi, which arise from the mastoid portion of the temporal bone
by short aponeurotic fibres. They are inserted into the lower part of the cranial
surface of the concha.
Relations. — Superficially, with the integument; deeply, with the mastoid portion
of the temporal bone and the posterior auricular artery and nerve.
Nerves. — The Attrahens and Attollens auriculam are supplied by the temporal
branch of the facial ; the Retrahens auriculam is supplied by the posterior auricu-
lar branch of the same nerve.
Actions. — In man, these muscles possess very little action: the Attrahens auric-
ulam draws the ear forward and upward; the Attollens auriculam slightly raises
it; and the Retrahens auriculam draws it backward.
3. The Palpebral Region (Fig. 260).
Orbicularis palpebrarum. Levator palpebrse.
Corrugator supercilii. Tensor tarsi.
Dissection (Fig. 258). — In order to expose the muscles of the face, continue the longi-
tudinal incision made in the dissection of the Occipito-frontalis down the median line of the
face to the tip of the nose, and from this point onward to the upper lip; and carry another
incision along the margin of the lip to the angle of the mouth, and transversely across the face
to the angle of the jaw. Then make an incision in front of the external ear, from the angle of
the jaw upward, to join the transverse incision made in exposing the Occipito-frontalis. These
incisions include a square-shaped flap, which should be removed in the direction marked in
the figure, with care, as the muscles at some points are intimately adherent to the integument.
The Orbicularis Palpebrarum (TO. orbicularis oculi) is a sphincter muscle, which
surrounds the circumference of the orbit and eyelids. It arises from the internal
angular process of the frontal bone, from the nasal process of the superior maxil-
lary bone in front of the lachrymal groove for the nasal duct, and from the anterior
surface and borders of a short tendon, the tendo oculi, or internal tarsal ligament,
placed at the inner angle of the orbit. From this origin the fibres are directed
outward, forming a broad, thin, and flat layer, which covers the eyelids, surrounds
the circumference of the orbit, and spreads out over the temple and downward on
the cheek. The internal or palpebral portion (pars palpebralis) of the Orbicularis is
thin and pale; it arises from the bifurcation of the tendo palpebrarum, and forms
a series of concentric curves, which are on the outer side of the eyelids inserted into
the external tarsal ligament. The external or orbital portion (pars orbitalis) is
thicker and of a reddish color: its fibres are well developed, and form complete
ellipses. The upper fibres of this portion blend with the Occipito-frontalis and
Corrugator supercilii.
THE PALPEBRAL REGION 373
Relations. — By its superficial surface, with the integument. By its deep surface,
above, with the Occipito-frontalis and Corrugator supercilii, with which it is inti-
mately blended, and with the supraorbital vessels and nerve; below, it covers the
lachrymal sac, and the origin of the Levator labii superioris alreque nasi, the
Levator labii superioris, and the Zygomaticus minor muscles. Internally, it is
occasionally blended with the Pyramidalis nasi. Externally, it lies on the temporal
fascia. On the eyelids it is separated from the conjunctiva by the Levator palpe-
brte, the tarsal ligaments, the tarsal plates, and the Meibomian glands.
The tendo oculi or internal tarsal ligament (ligamentum palpebrale mediate) is a
short tendon, about two lines in length and one in breadth, attached to the nasal
process of the superior maxillary bone in front of the lachrymal groove. Crossing
the lachrymal sac, it divides into two parts, each division being attached to the
inner extremity of the corresponding tarsal plate. As the tendon crosses the lach-
rymal sac, a strong aponeurotic lamina is given off from the posterior surface,
which expands over the sac, and is attached to the ridge on the lachrymal bone.
This is the reflected aponeurosis of the tendo oculi.
The external tarsal ligament (raphe palpebralis lateralis) is a much weaker struc-
ture than the tendo oculi. It is attached to the margin of the frontal process of
the malar bone, and passes inward to the outer commissure of the eyelids; it
connects together the outer extremities of the two tarsal cartilages.
USE OF TENDO OCULI. — Besides giving attachment to part of the Orbicularis
palpebrarum and to the tarsal plates, it serves to suck the tears into the lachrymal
sac, by its attachment to the sac. Thus, each time the eyelids are closed, the tendo
oculi becomes tightened, through the action of the Orbicularis, and draws the wall
of the lachrymal sac outward and forward, so that a vacuum is made in the sac,
and the tears are sucked along the lachrymal canals into it.
The Corrugator Supercilii (Figs. 259 and 260) is a small narrow, pyramidal
muscle, placed at the inner extremity of the eyebrow, beneath the Occipito-
frontalis and Orbicularis palpebrarum muscles. It arises from the inner extrem-
ity of the superciliary ridge, from whence its fibres pass upward and outward,
and are inserted into the deep surface of the skin, opposite the middle of the
orbital arch.
Relations. — By its anterior surface with the Occipito-frontalis and Orbicularis
palpebrarum muscles; by its posterior surface, with the frontal bone and supra-
trochlear nerve.
The Levator Palpebrse will be described with the muscles of the orbital region.
The Tensor Tarsi or Homer's Muscle (pars lacrimalis of the orbicularis pal-
pebrarum) (Fig. 261) is a small thin muscle about three lines in breadth and six
in length, situated at the inner side of the orbit, behind the tendo oculi. It is
usually considered to be composed of fibres derived from the Orbicularis palpe-
brarum. It arises from the crest and adjacent part of the orbital surface of the
lachrymal bone, and, passing across the lachrymal sac, divides into two slips,
which cover the lachrymal canals and are inserted into the tarsal plates internal
to the puncta lachrymalia. Its fibres appear to be continuous with those of the
palpebral portion of the Orbicularis palpebrarum; it is occasionally very indistinct.
Nerves. — The Orbicularis palpebrarum, Corrugator supercilii, and Tensor tarsi
are supplied by the facial nerve. Recent investigations tend to show that the
Orbicularis palpebrarum, Corrugator supercilii, and frontal part of the Occipito-
frontalis are in reality supplied by fibres of the motor oculi nerve, which descend
through the pons to join the facial nerve.
Actions. — The Orbicularis palpebrarum is the sphincter muscle of the eyelids.
The palpebral portion acts involuntarily, closing the lids gently, as in sleep or in
blinking; the orbicular portion is subject to the will. When the entire muscle is
brought into action, the skin of the forehead, temple, and cheek is drawn inward
374
THE MUSCLES AND FASCIA
toward the inner angle of the orbit, and the eyelids are firmly closed as a photo-
phobia. .When the skin of the forehead, temple, and cheek is thus drawn inward
by the action of the muscle it is thrown into folds, especially radiating from the
outer angle of the eyelids, which give rise in old age to the so-called "crow's feet."
The Levator palpebrse is the direct antagonist of this muscle; it raises the upper
eyelid and exposes the globe. The Corrugator supercilii draws the eyebrow
downward and inward, producing the vertical wrinkles of the forehead. It is the
"frowning" muscle, and may be regarded as the principal agent in the expression
of suffering. The Tensor tarsi draws the eyelids inward and compresses the eye-
lids and the extremities of the lachrymal canals against the surface of the globe
of the eye ; thus placing the canals in the most favorable situation for receiving
the tears. It serves, also, to compress the lachrymal sac.
FRONTAL SINUS
CORRUGATOR
SUPERCILII
PALPEBRAL PORTION
OF ORBICULARIS
PALPEBRARUM
IPUNCTA
LACHRYMALIA
ORBITAL PORTION OF
ORBICULARIS PALPEBRARUM
ANTRUM OF
HIGHMORE
FIG. 261. — The three portions of the Orbicularis palpebrarum muscle, and the relation of this muscle to the
Corrugator supercilii muscle, seen from behind. (Left side.) (Toldt.)
4. The Orbital Region (Fig. 262).
Levator palpebrse superioris. Rectus internus.
Rectus superior. Rectus externus.
Rectus inferior. Obliquus oculi superior.
Obliquus oculi inferior.
Dissection. — To open the cavity of the orbit, remove the skull-cap and brain; then saw
through the frontal bone at the inner extremity of the supraorbital ridge, and externally at its
junction with the malar. Break in pieces the thin roof of the orbit by a few slight blows of
the hammer, and take it away; drive forward the superciliary portion of the frontal bone
by a smart stroke, but do not remove it, as that would destroy the pulley of the Obliquus
superior. When the fragments are cleared away, the periosteum of the orbit will be exposed;
this being removed, together with the fat which fills the cavity of the orbit, the several muscles
of this region can be examined. The dissection will be facilitated by distending the globe
of the eye. In order to effect this, puncture the optic nerve near the eyeball with a curved
needle, and push the needle onward into the globe; insert the point of a blowpipe through
this aperture, and force a little air into the cavity of the eyeball; then apply a ligature round
the nerve so as to prevent the air escaping. The globe being now drawn forward, the muscles
will be put upon the stretch.
THE ORBITAL REGION
375
The Levator Palbebrae Superioris is thin, flat, and triangular in shape. It
arises from the under surface of the lesser wing of the sphenoid, above and in
front of the optic foramen, from which it is separated by the origin of the Superior
rectus (Fig. 263). At its origin it is narrow and tendinous, but soon becomes
broad and fleshy, and finally terminates in a wide aponeurosis, which is inserted
into the upper margin of the superior tarsal plate. From this aponeurosis a thin
expansion is continued onward, passing between the fibres of the Orbicularis
FIG. 262. — Muscles of the right orbit.
to be inserted into the skin of the lid, and some deeper fibres blend with an
expansion from the sheath of the Superior rectus muscle, and are with it pro-
longed into the conjunctiva.
Relations. — By its upper surface, with the frontal nerve and supraorbital
artery, the periosteum of the orbit and lachrymal gland; and, in the lid, with the
inner surface of the tarsal ligament; by its under surface, with the Superior rectus,
and, in the lid, with the conjunctiva. A small branch of the motor-oculi nerve
enters its under surface.
The Superior Rectus (TO. rectus superior), the thinnest and narrowest of the
four Recti, arises from the upper margin of the optic foramen (Fig. 263) beneath
the Levator palpebrse, and from the fibrous sheath of the optic nerve; and is
inserted by a tendinous expansion into the sclerotic coat, about three or four
lines from the margin of the cornea.
Relations. — By its upper surface, with the Levator palpebrse; by its under sur-
face, with the optic nerve, the ophthalmic artery, the nasal nerve, and the branch
of the motor-oculi nerve which supplies it; and, in front, with the tendon of the
Superior oblique and the globe of the eye.
The Inferior Rectus (TO. rectus inferior) and the Internal Rectus (TO. rectus
medialis) arise by a common tendon, the ligament of Zinn1 (annulus tendineus
commnnis). which is attached round the circumference of the optic foramen,
except at its upper and outer part (Fig. 263).
The External Rectus (TO. rectus lateralis) has two heads: the upper one arises
from the outer margin of the optic foramen immediately beneath the Superior
rectus; the lower head, partly from the ligament of Zinn and partly from a small
1 The ligament of Zinn ought, perhaps more appropriately, to be termed the apnneurosis or tendon of Zinn,
Mr. C. B. Lockwood has described a somewhat similar structure on the under surface of the Superior rectus
muscle, which is attached to the lesser wing of the sphenoid, forming the upper and outer margin of the optic
foramen. This superior tendon gives origin to the Rectus superior, the superior head of the External rectus.
and the upper part of the Internal rectus. — Journal of Anatomy and Physiology, vol. xx. part i. p. 1.
376 THE MUSCLES AND FASCIA
pointed process of bone on the lower margin of the sphenoidal fissure (Fig. 263).
Each muscle passes forward in the position implied by its name, to be inserted by
a tendinous expansion, the tunica albuginea, into the sclerotic coat, about three or
four lines from the margin of the cornea. Between the two heads of the External
rectus is a narrow interval through which passes
superior. the motor-oculi, the nasal branch of the ophthal-
m^c division of tne trigemiiial, and the abducent
nerve, and the ophthalmic vein. Although
nearly all of these muscles present a common
origin and are inserted in a similar manner
into the sclerotic coat, there are certain differ-
ences to be observed in them as regards their
length and breadth. The Internal rectus is the
broadest, the External is the longest, and the
JIB**, inferior, y Superior is the thinnest and narrowest.
FIG. 263. — The relative position and attach- T^o Sn-narinr fthlimiP ( *n nhliniiiia <ntv\0nrw\
ment of the muscles of the left eyeball. L ne pUperiOI UDliqUC (m. OOliqUUS Superior)
is a fusiform muscle placed at the upper and
inner side of the orbit, internal to the Levator palpebrse. It arises about a line
above the inner margin of the optic foramen (Fig. 263), and, passing forward to
the inner angle of the orbit, terminates in a rounded tendon, which plays in a ring
or pulley, the trochlea (trochlea m. obliqui superior-is) , formed by a cartilaginous
tissue attached to a depression beneath the internal angular process of the frontal
bone, the contiguous surfaces of the tendon and ring being lined by a delicate
synovial membrane and enclosed in a thin fibrous investment. The tendon is
reflected backward, outward, and downward beneath the Superior rectus to the
outer part of the globe of the eye, and is inserted into the sclerotic coat, behind
the equator of the eyeball, the insertion of the muscle lying between the Superior
and External recti.
Relations. — By its upper surface, with the periosteum covering the roof of the
orbit and the trochlear nerve: the tendon, where it lies on the globe of the eye,
is covered by the Superior rectus; by its under surface, with the nasal nerve,
ethmoidal arteries, and the upper border of the internal rectus.
The Inferior Oblique (m. obliquus inferior} is a thin, narrow muscle placed near
the anterior margin of the orbit. It arises from a depression on the orbital plate
of the superior maxillary bone, external to the lachrymal groove (Fig. 262).
Passing outward, backward, and upward between the Inferior rectus and the
floor of the orbit, and then between the eyeball and the External rectus, it is
inserted into the outer part of the sclerotic coat between the Superior and External
recti, near to, but somewhat behind, the tendon of insertion of the Superior oblique.
Relations.— By its ocular surface, with the globe of the eye and with the Inferior
rectus ; by its orbital surface, with the periosteum covering the floor of the orbit,
and with the External rectus. Its borders look forward and backward; the poste-
rior one receives a branch of the motor oculi nerve.
The orbital muscle or Miiller's muscle (musculus orbitalis), which spans the
spheno-maxillary fissure and infraorbital groove, is composed of non-striated
fibres, and is a rudimentary structure continuous with the periosteum of the orbit.1
Nerves. — The Levator palpebrse, Inferior oblique, and all the Recti excepting
the External, are supplied by the motor oculi nerve; the Superior oblique, by the
trochlear; the External rectus, by the abducent.
Actions. — The Levator palpebrse raises the upper eyelid, and is the direct
antagonist of the Orbicularis palpebrarum. The four Recti muscles are attached
in such a manner to the globe of the eye that, acting singly, they will turn it either
1 See F. Groyer, in the Vienna Siztungsberiehte der Kaiserlichen Akademie der Wissenschaften, 1903, Band cxii.
—Bo. of 15th English Edition.
THE ORBITAL REGION 377
upward, downward, inward, or outward, as expressed by their names. The
movement produced by the Superior or Inferior rectus is not quite a simple one,
for, inasmuch as they pass obliquely outward arid forward to the eyeball, the
elevation or depression of the cornea must be accompanied by a certain deviation
inward, with a slight amount of rotation, which, however, is corrected by the
Oblique muscles, the Inferior oblique correcting the deviation inward of the
Superior rectus, and the Superior oblique that of the Inferior rectus. The con-
traction of the External and Internal recti, on the other hand, produces a purely
horizontal movement. If any two contiguous recti of one eye act together, they
carry the globe of the eye in the diagonal of these directions — viz., upward and
inward, upward and outward, downward and inward, or downward and outward.
The movement of circumduction, as in looking round a room, is performed by
the alternate action of the four Recti. The Oblique muscles rotate the eyeball
on its antero-posterior axis, this kind of movement being required for the correct
viewing of an object when the head is moved laterally, as from shoulder to shoulder,
in order that the picture may fall in all respects on the same part of the retina of
each eye.1 It should be noted that sometimes the corresponding Recti and some-
times the opposite ones of the two eyes act together; for instance, the two superior
and inferior Recti carry both eyeballs upward and downward, respectively. In
looking toward the right the right External and left Internal recti act together,
the reverse being the case in looking toward the left. In turning both eyes toward
the middle line, as in directing our vision toward an object less than twenty feet
distant, the two internal recti act together.
Fasciae of the Orbit. — The connective tissue of the orbit is in various places
condensed into thin membranous layers, which may be conveniently described as
(1) the orbital fascia; (2) the sheaths of the muscles; and (3) the covering of the
eyeball.
(1) The Orbital Fascia. — This forms the periosteum of the orbit. It is loosely
connected to the bones, from which it can be readily separated. Behind, it is
connected with the dura by processes which pass through the optic foramen
and sphenoidal fissure, and with the sheath of the optic nerve. In front it is
connected with the periosteum at the margin of the orbit, and sends off a process
which assists in forming the palpebral fascia. From its internal surface two
processes are given off — one to enclose the lachrymal gland, the other to hold the
pulley of the Superior oblique muscle in position.
(2) The Sheaths of the Muscles. — The sheaths of the muscles give off expansions
to the margins of the orbit which limit the action of the muscles.
(3) The Covering of the Eyeball — Tenon's capsule — surrounds the posterior
two- thirds of the eyeball; it will be described in the sequel.
Surgical Anatomy. — The position and exact point of insertion of the tendons of the
Internal and External recti muscles into the globe should be carefully examined from the front
of the eyeball, as the surgeon is often required to divide the one or the other muscle for the cure
of strabismus (squint). In convergent strabismus, which is the more common form of the disease,
the eye is turned inward, requiring the division of the Internal rectus. In the divergent form,
which is more rare, the eye is turned outward, the External rectus being especially implicated.
The deformity produced in either case is to be remedied by division of one or the other muscle.
The operation is thus performed : The lids are to be well separated ; the eyeball being rotated
outward or inward, the conjunctiva should be raised by a pair of forceps and divided immediately
beneath the lower border of the tendon of the muscle to be divided, a little behind its insertion
into the sclerotic; the submucous areolar tissue is then divided, and into the small aperture
, thus made a blunt hook is passed upward between the muscle and the globe, and the tendon of
the muscle and conjunctiva covering it divided by a pair of blunt-pointed scissors. Or the
tendon may be divided by a subconjunctival incision, one blade of the scissors being passed
1 On the Oblique Muscles of the Eye in Man and Vertebrate Animals, by John Struthers, M.D., in Anatom-
ical and Physiological Observations. For a fuller account of the various co-ordinate actions ot the muscles of
a single eye and of both eyes than our space allows see Dr. M. F'oster's Text-book of Physiology. — ED. of loth
English edition.
378 THE MUSCLES AND FASCIA
upward between the tendon and the conjunctiva, and the other between the tendon and the
sclerotic. The student, when dissecting these muscles, should remove on one side of the subject
the conjunctiva from the front of the eye, in order to see more accurately the position of the
tendons, while on the opposite side the operation may be performed. Inflammation of the
synovial membrane lining the trochlea of the Superior oblique may lead to the formation of
a cyst of considerable size.
In performing enucleation of the eyeball the conjunctiva is clipped with scissors near the
cornea and the capsule of Tenon is divided with it. One rectus muscle after another is caught
up on a blunt hook and divided. The scissors are now pushed well in along the outer orbital
wall. and the optic nerve is divided. Finally the oblique muscles, the ciliary vessels and nerves,
and fragments of tissue helping to retain the globe are cut and the eyeball is enucleated.
An orbital abscess is evacuated by making an incision close to the border of the orbit, above
or below the eyeball.
5. The Nasal Region (Fig. 260).
Pyramidalis nasi. Dilator naris anterior.
Levator labii superioris alseque nasi. Compressor nasi.
Dilator naris posterior. Compressor narium minor.
Depressor alse nasi.
The Pyramidalis Nasi is a small pyramidal slip placed over the nasal bone.
Its origin, is by tendinous fibres from the fascia'covering the lower part of the nasal
bone and upper part of the cartilage, where it blends with the Compressor nasi,
and it is inserted into the skin over the lower part of the forehead between the
two eyebrows, its fibres decussating with those of the Occipito-frontalis (see
page 371).
Relations. — By its upper surface, with the skin; by its under surface, with the
frontal and nasal bones.
The Levator Labii Superioris Alaeque Nasi is a thin triangular muscle placed
by the side of the nose, and extending between the inner margin of the orbit and
upper lip. It arises by a pointed extremity from the upper part of the nasal
process of the superior maxillary bone, and, passing obliquely downward and
outward, divides into two slips, one of which is inserted into the cartilage of the
ala of the nose and the under surface of the skin over the ala; the other is pro-
longed into the upper lip, becoming attached to the under surface of the skin
and blended with the Orbicularis oris and Levator labii superioris proprius.
Relations. — In front, with the integument, and with a small part of the Orbicu-
laris palpebrarum above.
The Dilator Naris Posterior is a small muscle which is placed partly beneath
the elevator of the nose and lip. It arises from the margin of the nasal notch of
the superior maxilla and from the sesamoid cartilages, and is inserted into the
skin near the margin of the nostril.
The Dilator Naris Anterior is a thin delicate fasciculus passing from the
cartilage of the ala of the nose to the integument near its margin. This muscle is
situated in front of the preceding.
The Compressor Nasi is a small, thin, triangular muscle arising by its apex
from the superior maxillary bone, above and a little external to the incisive fossa;
its fibres proceed upward and inward, expanding into a thin aponeurosis which
is attached to the fibro-cartilage of the nose and is continuous on the bridge of
the nose with that of the muscle of the opposite side and with the aponeurosis of
the Pyramidalis nasi. His uses the term musculus nasalis to include the Com-
pressor nasi (transverse portion of the nasal muscle), and the Dilatator naris
posterior and the Dilatator naris anterior (alar portion of the nasal muscle).
The Compressor Narium Minor is a small muscle attached by one end to the
alar cartilage, and by the other to the integument at the end of the nose.
The Depressor Alae Nasi (depressor septi) is a short radiated muscle arising
from the incisive fossa of the superior maxilla; its fibres ascend to be inserted into
379
the septum and back part of the ala of the nose. This muscle lies between the
mucous membrane and muscular structure of the lip.
Nerves. — All of the muscles of this group are supplied by the facial nerve.
Actions. — The Pyramidalis nasi draws down the inner angle of the eyebrows
and produces transverse wrinkles over the bridge of the nose. The Levator labii
superioris alaeque nasi draws upward the upper lip and ala of the nose ; its most
important action is upon the nose, which it dilates to a considerable extent. The
action of this muscle produces a marked influence over the countenance, and it is
the principal agent in the expression of contempt and disdain. The two Dilatatores
nasi enlarge the aperture of the nose. Their action in ordinary breathing is to
resist the tendency of the nostrils to close from atmospheric pressure, but in
difficult breathing they may be noticed to be in violent action, as well as .in some
emotions, as anger. The Depressor alae nasi is a direct antagonist of the other
muscles of the nose, drawing the ala of the nose downward, and thereby constrict-
ing the aperture of the nares. The Compressor nasi depresses the cartilaginous
part of the nose and compresses the alae together.
6. The Superior Maxillary Region (Fig. 260).
Levator labii superioris. Zygomaticus major.
Levator anguli oris. Zygomaticus minor.
By the term musculus quadratus labii superioris, His includes three muscles.
The caput angulare is called in this book the Levator labii superioris alseque nasi.
The caput infraorbitale is called the Levator labii superioris. The caput zygomati-
cum is called the Zygomaticus minor.
The Levator Labii Superioris (proprius) is a thin muscle of a quadrilateral
form. It arises from the lower margin of the orbit immediately above the infra-
orbital foramen, some of its fibres being attached to the superior maxilla, others
to the malar bone; its fibres converge to be inserted into the muscular substance
of the upper lip.
Relations.— By its superficial surface above, with the lower segment of the
Orbictilaris palpebrarum; below, it is subcutaneous. By its deep surface it con-
ceals the origin of the Compressor nasi and Levator anguli oris muscles, and the
infraorbital vessels and nerve, as they escape from the infraorbital foramen.
The Levator Anguli Oris (TO. caninus] arises from the canine fossa immediately
below the infraorbital foramen ; its fibres incline downward and a little outward, to
be inserted into the deep surface of the skin and into the subcutaneous tissue
near the angle of the mouth and intermingles with the fibres of the Zygomaticus
major, the Depressor anguli oris, and the Orbicularis.
Relations. — By its superficial surface, with the Levator labii superioris and
the infraorbital vessels and nerves; by its deep surface, with the superior maxilla,
the Buccinator, and the mucous membrane.
The Zygomaticus Major (TO. Zygomaticus} is a slender fasciculus which
arises from the malar bone, in front of the zygomatic suture, and, descending
obliquely downward and inward, is inserted into the deep surface of the skin
and subcutaneous tissue at the outer portion of the upper lip and into the angle
of the mouth, where it blends with the fibres of the Levator anguli oris, the
Orbicularis oris, and the Depressor anguli oris.
Relations. — By its superficial surface, with the subcutaneous adipose tissue;
by its deep surface, with the Masseter and Buccinator muscles and the facial artery
and vein.
The Zygomaticus Minor, which is often absent, arises from the malar bone
immediately behind the maxillary suture, and, passing downward and inward, is
inserted into the deep surface of the skin and the adjacent muscles at the upper
margin of the exposed vermilion surface of the lip midway between the middle
380 THE MUSCLES AND FASCIAE
line of the lip and the angle of the mouth. It is continuous with the Orbicularis
oris at the outer margin of the Levator labii superioris. It lies in front of the
preceding.
Relations. — By its superficial surface, with the integument and the Orbicularis
palpebrarum above; by its deep surface, with the Masseter, Buccinator, and
Levator anguli oris, and the facial artery and vein.
Nerves. — This group of muscles is supplied by the facial nerve.
Actions. — The Levator labii superioris is the proper elevator of the upper lip,
carrying it at the same time a little forward. It assists in forming the naso-labial
ridge, which passes from the side of the nose to the upper lip and gives to the
face an expression of sadness. The Levator anguli oris raises the angle of the
mouth and draws it inward, and assists the Levator labii superioris in producing
the naso-labial ridge. The Zygomaticus major draws the angle of the mouth
backward and upward, as in laughing; whilst the Zygomaticus minor, being
inserted into the outer part of the upper lip and not into the angle of the
mouth, draws it backward, upward, and outward, and thus gives to the face
an expression of sadness.
7. The Mandibular Region (Fig. 260).
Levator labii inferioris. Depressor labii inferioris.
Depressor anguli oris.
Dissection. — The muscles in this region may be dissected by making a vertical incision
through the integument from the margin of the lower lip to the chin; a second incision should
then be carried along the margin of the lower jaw as far as the angle, and the integument care-
fully removed in the direction shown in Fig. 258.
The Levator Labii Inferioris or Levator Menti (m. mentalis) is to be dissected
by everting the lower lip and raising the mucous membrane. It is a small conical
fasciculus placed on the side of the frsenum of the lower lip. It arises from the
incisive fossa, external to the symphysis of the lower jaw; its fibres descend to
be inserted into the integument of the chin.
Relation. — On its inner surface, with the mucous membrane; in the median
line, it is blended with the muscle of the opposite side; and on its outer side, with
the Depressor labii inferioris.
The Depressor Labii Inferioris or Quadratus Menti (m. quadratus labii
inferioris} (Fig. 264) is a small quadrilateral muscle. It arises from the external
oblique line of the lower jaw, between the symphysis and mental foramen, and
passes obliquely upward and inward, to be inserted into the integument of the
lower lip, its fibres blending with the Orbicularis oris and with those of its fellow
of the opposite side. It is continuous with the fibres of the Platysma at its origin.
This muscle contains much yellow fat intermingled with its fibres.
Relations. — By its superficial surface, with part of the Depressor anguli oris
and with the integument, to which it is closely connected; by its deep surface,
with the mental vessels and nerves, the mucous membrane of the lower lip, the
labial glands, and the Levator menti, with which it is intimately united.
The Depressor Anguli Oris or Triangularis Menti (m. triangularis) (Fig. 260)
is triangular in shape, arising, by its broad base, from the external oblique line of
the lower jaw, from whence its fibres pass upward, to be inserted, by a narrow
fasciculus, into the angle of the mouth. It is continuous with the Platysma at
its origin and with the Orbicularis oris and Risorius at its insertion, and some of
its fibres are directly continuous with those of the Levator anguli oris. Muscular
fibres connecting the two muscles below the chin are occasionally met with; they
constitute the Musculus transversus menti of His and Waldeyer.
THE INTERMAXILLARY REGION 381
Relations. — By its superficial surface, with the integument; by its deep surface,
with the Depressor labii inferioris and Buccinator.
Nerves. — This group of muscles is supplied by the facial nerve.
Actions. — The Levator labii inferioris raises the lower lip and protrudes it
forward, and at the same time wrinkles the integument of the chin, expressing
doubt or disdain. The Depressor labii inferioris draws the lower lip directly
downward and a little outward, as in the expression of irony. The Depressor
anguli oris depresses the angle of the mouth, being the antagonist to the Levator
anguli oris and Zygomaticus major; acting with these muscles, it will draw the
angle of the mouth directly backward.
8. The Intermaxillary Region.
Orbicularis oris. Buccinator. Risorius.
Dissection. — The dissection of these muscles may be considerably facilitated by filling the
cavity of the mouth with tow, so as to distend the cheeks and lips; the mouth should then be
closed by a few stitches and the integument carefully removed from the surface.
The Orbicularis oris (Figs. 260 and 264) is not a sphincter muscle, like the Orbic-
ularis palpebrarum, but consists of numerous strata of muscular fibres, having dif-
ferent directions, which surround the orifice of the mouth. These fibres are par-
tially derived from the other facial muscles which are inserted into the lips, and are
partly fibres proper to the lips themselves. Of the former, a considerable number
are derived from the Buccinator and form the deeper stratum of the Orbicularis.
Some of them — namely, those near the middle of the muscle — decussate at the
angle of the mouth, those arising from the upper jaw passing to the lower lip, and
those from the lower jaw to the upper lip. Other fibres of the muscle, situated at
its upper and lower part, pass across the lips from side to side without decussation.
Superficial to this stratum is a second, formed by the Levator and Depressor
anguli oris, which cross each other at the angle of the mouth, those from the
Depressor passing to the upper lip, and those from the Levator to the lower lip,
along which they run to be inserted into the skin near the median line. In addi-
tion to these there are fibres from the other muscles inserted into the lips — the
Levator labii superioris, the Levator labii superioris alseque nasi, the Zygomatici,
and the Depressor labii inferioris; these intermingle with the transverse fibres
above described, and have principally an oblique direction. The proper fibres of
the lips are oblique, and pass from the under surface of the skin to the mucous
membrane through the thickness of the lip. And in addition to these are fibres
by which the muscle is connected directly with the maxillary bones and the
septum of the nose. These consist, in the upper lip, of four bands, two of
which (m. incisivus superior} arise from the alveolar border of the superior
maxilla, opposite the lateral incisor tooth, and, arching outward on each side,
are continuous at the angles of the mouth with the other muscles inserted into
this part. The two remaining muscular slips, called the Nasolabialis, connect
the upper lip to the back of the septum of the nose: as they descend from the
septum an interval is left between them. It is this interval which forms the depres-
sion seen on the surface of the skin beneath the septum of the nose, which is
called the philtrum. The additional fibres for the lower segment (m. incisivus
inferior) arise from the inferior maxilla, externally to the Levator labii inferioris,
and arch outward to the angles of the mouth, to join the Buccinator and the other
muscles attached to this part.
Relations. — By its superficial surface, with the integument, to which it is closely
connected; by its deep surface, with the buccal mucous membrane, the labial
glands, and coronary vessels; by its outer circumference it is blended with the
382
THE MUSCLES AND FASCIA
numerous muscles which converge to the mouth from the various parts of the face.
Its inner circumference is free, and covered by the mucous membrane.
The Buccinator (Fig. 264) is a broad, thin muscle, quadrilateral in form,
which occupies the interval between the jaws at the side of the face. It arises
from the outer surface of the alveolar processes of the upper and lower jaws,
FIG. 264. — Temporal and deep muscles about the mouth. (Testut.)
corresponding to the three molar teeth, and, behind, from the anterior border of
the ptery go-maxillary ligament. The fibres converge toward the angle of the
mouth, where the central fibres intersect each other, those from below being
continuous with the upper segment of the Orbicularis oris, and those from above
with the inferior segment ; the highest and lowest fibres continue forward uninter-
ruptedly into the corresponding segment of the lip, without decussation.
THE TEMPORO-MANDIBULAR REGION 383
Relations. — By its superficial surface, behind, with a large mass of fat, the sucking
or suctorial pad (corpus adiposum buccac) , which separates it from the ramus of the
lower jaw, the Masseter, and a small portion of the Temporal muscle. The suck-
ing pad is much more developed relatively in children than in adults. It assists
sucking by aiding the cheek to resist atmospheric pressure. The buccinator
muscle is in relation, anteriorly, with the Zygomatici, Risorius, Levator anguli
oris, Depressor anguli oris, and Stenson's duct, which pierces it opposite the
second molar tooth of the upper jaw; the facial artery and vein cross it from below
upward; it is also crossed by the branches of the facial and buccal nerves; by
its internal surface, with the buccal glands and mucous membrane of the mouth.
The Ptery go-maxillary or Pterygo-mandibular Ligament (raphe pterygomandib-
ularis) separates the Buccinator muscle from the Superior constrictor of the
pharynx. It is a tendinous thickening of the bucco-pharyngeal fascia, attached by
one extremity to the apex of the internal pterygoid plate, and by the other to the
posterior extremity of the internal oblique line of the lower jaw. Its inner surface
corresponds to the cavity of the mouth, and is lined by mucous membrane. Its
outer surface is separated from the ramus of the jaw by a quantity of adipose
tissue. Its posterior border gives attachment to the Superior constrictor of the
pharynx; its anterior border, to the fibres of the Buccinator.
The Bucco-pharyngeal fascia (fascia buccopharyngea) is a thin fascia covering
the external surface of the Buccinator muscle. It is gradually lost in front of the
angle of the mouth. Posteriorly it is continued over the external surface of the
throat muscles. Its thickened cord-like portion is the stylo-mandibular ligament.
The Risorius or Santorini's Muscle (ra. risorius) (Fig. 260) consists of a
narrow bundle of fibres which arises in the fascia over the Masseter muscle,
and, passing horizontally forward, is inserted with the Depressor anguli oris into
the subcutaneous and muscular tissue at the angle of the mouth. It is placed
superficial to the Platysma, and is broadest at its outer extremity. This muscle
varies much in its size and form.
Nerves. — The muscles in this group are all supplied by the facial nerve. The
buccal branch of the inferior maxillary nerve pierces the Buccinator muscle, and
by some anatomists is regarded as partly supplying this muscle. Probably it
merely pierces it on its way to the mucous membrane of the cheek.
Actions. — The Orbicularis oris in its ordinary action produces the direct closure
of the lips; by its deep fibres, assisted by the oblique ones, it closely applies the
lips to the alveolar arch. The superficial part, consisting principally of the decus-
sating fibres, brings the lips together and also protrudes them forward. The Buc-
cinators contract and compress the cheeks, so that, during the process of mastica-
tion, the food is kept under the immediate pressure of the teeth. When the cheeks
have been previously distended with air, the Buccinator muscles expel it from
between the lips, as in blowing a trumpet. Hence the name (buccina, a trumpet).
The Risorius retracts the angles of the mouth, and produces 'the unpleasant
expression which is sometimes seen in tetanus, and is known as risus sardonicus, the
sardonic laugh.
9. The Temporo-mandibular Region.
Masseter. Temporal.
The Masseteric Fascia (fascia parotideomassetericd) covers the outer and inner
surfaces of the parotid gland as a thick membrane, called the parotid fascia. It
passes forward, and becomes thinner to cover the Masseter muscle, to which it
is firmly connected. It is derived from the deep cervical fascia. Above, this
fascia is attached to the lower border of the zygoma. It is lost in front below
the Risorius and Platysma.
The Masseter Muscle is exposed by the removal of this fascia (Fig. 260) ; it is a
short, thick muscle, somewhat quadrilateral in form, consisting of two portions,
384 THE MUSCLES AND FASCIA
superficial and deep. The superficial portion, the larger, arises by a thick, tendinous
aponeurosis from the malar process of the superior maxilla, and from the anterior
two-thirds of the lower border of the zygomatic arch: its fibres pass downward
and backward, to be inserted into the angle and lower half of the outer surface
of the ramus of the jaw. The deep portion is much smaller and more muscular
in texture; it arises from the posterior third of the lower border and the whole of
the inner surface of the zygomatic arch; its fibres pass downward and forward,
to be inserted into the upper half of the ramus and outer surface of the coronoid
process of the jaw, The deep portion of the muscle is partly concealed, in front
by the superficial portion; behind, it is covered by the parotid gland. The fibres
of the two portions are united at their insertion.
Relations. — By its superficial surface, with the Zygomatici, the parotid gland
and Socia parotidis, and Stenson's duct; the branches of the facial nerve and
the transverse facial vessels, which cross it; the masseteric fascia; the Risorius,
Platysma myoides, and the integument; by its deep surface, with the Temporal
muscle at its insertion, the ramus of the jaw, the Buccinator and the long
buccal nerve, from which it is separated by a mass of fat (suctorial or sucking pad).
The masseteric nerve and artery enter in on its under surface. Its posterior margin
is overlapped by the parotid gland. Its anterior margin projects over the Bucci-
nator muscle, and the facial vein lies on it below.
Temporal Fascia (fascia temporalis). — The temporal fascia is seen, at this stage
of a dissection, covering in the Temporal muscle. It is a strong, fibrous invest-
ment, covered, on its outer surface, by the Attrahens and Attollens auricularn mus-
cles, the aponeurosis of the Occipito-frontalis, and by part of the Orbicularis palpe-
brarum. The temporal vessels and the auriculo-ternporal nerve cross it from below
upward. Above, it is a single layer, attached to the entire extent of the upper tem-
poral ridge; but below, where it is attached to the zygoma, it consists of two layers,
one of which is inserted into the outer, and the other into the inner, border of the
zygomatic arch. A small quantity of fat, the orbital branch of the temporal artery,
and a filament from the orbital, or temporo-rnalar, branch of the superior maxillary
nerve are contained between these two layers. It affords attachment by its inner
surface to the superficial fibres of the Temporal muscle.
Dissection. — In order to expose the Temporal muscle, remove the temporal fascia, which
may be effected by separating it at its attachment along the upper border of the zygoma, and
dissecting it upward from the surface of the muscle. The zygomatic arch should then
be divided in front at its junction with the malar bone, and behind near the external auditory
meatus, and drawn downward with the Masseter, which should be detached from its inser-
tion into the ramus and angle of the jaw. The whole extent of the Temporal muscle is then
exposed.
The Temporal Muscle (m. temporalis) (Figs. 264 and 265) is a broad, radiating
muscle situated at the side of the head and occupying the entire extent of the tem-
poral fossa. It arises from the whole of the temporal fossa except that portion of it
that is formed by the malar bone. Its attachment extends from the external angular
process of the frontal in front to the mastoid portion of the temporal behind, and
from the curved line on the frontal and parietal bones above to the pterygoid ridge
on the great wing of the sphenoid below. It is also attached to the inner surface of
the temporal fascia. Its fibres converge as they descend, and terminate in an apon-
eurosis, the fibres of which, radiated at its commencement, converge into a thick
and flat tendon, which is inserted into the inner surface, apex, and anterior border
of the coronoid process of the jaw, nearly as far forward as the last molar tooth.
Relations. — By its superficial surface, with the integument, the Attrahens and
Attollens auriculam muscles, the temporal vessels and nerves, the aponeurosis of
the Occipito-frontalis, the temporal fascia, the zygoma, and Masseter; by its
deep surface, with the temporal fossa, the External pterygoid and part of the
Buccinator muscles, the internal maxillary artery and its deep temporal branches,
THE PTERYGO-MANDIBULAR REGION
385
and the deep temporal nerves. Behind the tendon are the masseteric vessels and
nerve, and in front of it the buccal vessels and nerve. Its anterior border is sepa-
rated from the malar bone by a mass of fat.
Nerves. — Both muscles are supplied by the inferior maxillary nerve.
FIG. 265. — The Temporal muscle, the zygoma and Masseter having been removed.
10. The Pterygo-mandibular Region (Figs. 266, 267).
External pterygoid.
Internal pterygoid.
Dissection. — The Temporal muscle having been examined, saw through the base of the
coronoid process, and draw it upward, together with the Temporal muscle, which should be
detached from the surface of the temporal fossa. Divide the ramus of the jaw just below the
condyle, and also, by a transverse incision extending across the middle, just above the dental
foramen; remove the fragment, and the Pterygoid muscles will be exposed.
FIG. 266. — The Pterygoid muscles, the zygomatic arch, and a portion of the ramus of the jaw having
been removed.
25
386
THE MUSCLES AND FASCIA
The External Pterygoid Muscle (m. pterygoideus externus) is a short, thick
muscle, somewhat conical in form, which extends almost horizontally between the
zygomatic fossa and the condyle of the jaw. It arises by two heads, separated
by a slight interval: the upper head arises from the inferior surface of the greater
wing of the sphenoid and from the pterygoid ridge, which separates the zygo-
matic from the temporal fossa; the lower head from the outer surface of the external
pterygoid plate. 'Its fibres pass horizontally backward and outward, to be inserted
into a depression in front of the neck of the condyle of the lower jaw and into the
corresponding part of the interarticular fibre-cartilage.
FIG. 267. — Pterygoid muscles, viewed from behind, the back portion of the skull having been removed.
(Testut.)
Relations. — By its external surface, with the ramus of the lower jaw, the internal
maxillary artery, which crosses it,1 the tendon of the Temporal muscle, arid the
Masseter; by its internal surface it rests against the upper part of the Internal
pterygoid muscle, the internal lateral ligament, the middle meningeal artery, and
inferior maxillary nerve; by its upper border it is in relation with the temporal and
masseteric branches of the inferior maxillary nerve; by its lower border it is in
relation with the inferior dental and gustatory nerves. Through the interval
between the two portions of the muscle, the buccal nerve emerges and the internal
maxillary artery passes, when the trunk of this vessel lies on the muscle.
The Internal Pterygoid Muscle (m. pterygoideus internus) is a thick, quadri-
lateral muscle, and resembles the Masseter in form. It arises from the pterygoid
fossa, being attached to the inner surface of the external pterygoid plate and to
the grooved surface of the tuberosity of the palate bone, and by a second slip from
1 This is the usual relation, but in many cases the artery will be found below the muscle. — ED. of 15th English
edition.
MUSCLES AND FASCIA OF THE NECK 387
the outer surface of the tuberosities of the palate and superior maxillary bones;
its fibres pass downward, outward, and backward, to be inserted, by a strong, ten-
dinous lamina, into the lower and back part of the inner side of the ramus and
angle of the lower jaw, as high as the dental foramen.
Relations. — By its external surface, with the ramus of the lower jaw, from
which it is separated, at its upper part, by the External pterygoid muscle, the
internal lateral ligament, the internal maxillary artery, the dental vessels and
nerves, and the lingual nerve, and a process of the parotid gland. By its internal
surface, with the Tensor palati, being separated from the Superior constrictor of
the pharynx by a cellular interval.
Nerves. — These muscles are supplied by the inferior maxillary nerve.
Actions. — The Temporal and Masseter and Internal pterygoid raise the lower
jaw against the upper with great force. The superficial portion of the Masseter
assists the External pterygoid in drawing the lower jaw forward upon the upper,
the jaw being drawn back again by the deep fibres of the Masseter and posterior
fibres of the Temporal. The External pterygoid muscles are the direct agents in
the trituration of the food, drawing the lower jaw directly forward, so as to make
the lower teeth project beyond the upper. If the muscle of one side acts, the
corresponding side of the jaw is drawn forward, and, the other condyle remaining
fixed, the symphysis deviates to the opposite side. The alternation of these move-
ments on the two sides produces trituration.
Surface Form. — The outline of the muscles of the head and face cannot be traced on the
surface of the body, except in the case of two of the masticatory muscles. Those of the head
are thin, so that the outline of the bone is perceptible beneath them. Those in the face are
small, covered by soft skin, and often by a considerable layer of fat, so that their outline is con-
cealed, but they serve to round off and smooth prominent borders and to fill up what would be
otherwise unsightly angular depressions. Thus, the Orbicularis palpebrarum rounds off the
prominent margin of the orbit, and the Pyramidalis nasi fills in the sharp depression beneath
the glabella, and thus softens and tones down the abrupt depression which is seen on the
unclothed bone. In like manner, the labial muscles, converging to the lips and assisted by the
superimposed fat, fill in the sunken hollow of the lower part of the face. Although the muscles
of the face are usually described as arising from the bones and inserted into the nose, lips, and
corners of the mouth, they have fibres inserted into the skin of the face along their whole
extent, so that almost every point of the skin of the face has its muscular fibre to move it;
hence it is that when in action the facial muscles produce alterations in the skin-surface,
giving rise to the formation of various folds or wrinkles, or otherwise altering the relative
position of the parts, so as to produce the varied expressions with which the face is endowed;
hence these muscles are termed the muscles of expression. The only two muscles in this
region which greatly influence surface form are the Masseter and the Temporal. The Masseter
is a quadrilateral muscle, which imparts fulness to the hinder part of the cheek. When the
muscle is firmly contracted, as when the teeth are clenched, its outline is plainly visible;
the anterior border forms a prominent vertical ridge, behind which is a considerable fulness,
especially marked at the lower part of the muscle; this fulness is entirely lost when the
mouth is opened and the muscle no longer in a state of contraction. The Temporal muscle
is fan-shaped, and fills the Temporal fossa, substituting for it a somewhat convex form, the
anterior part of which, on account of the absence of hair over the temple, is more marked than
the posterior, and stands out in strong relief when the muscle is in a state of contraction.
MUSCLES AND FASCLE OF THE NECK.
The muscles of the neck may be arranged into groups corresponding with the
region in which they are situated.
These groups are nine in number:
1. Superficial Cervical Region. 5. Muscles of the Pharynx.
2. Depressors of the Os Hyoideum 6. Muscles of the Soft Palate.
and Larynx. 7. Muscles of the Anterior Ver-
3. Elevators of the Os Hyoideum tebral Region.
and Larynx. 8. Muscles of the Lateral Ver-
4. Muscles of the Tongue. tebral Region.
9. Muscles of the Larynx.
388
THE MUSCLES AND FASCIA
The muscles contained in each of these groups are the following:
I. Superficial Region.
Platysma myoides.
Sterno-cleido-mastoid .
Infra-hyoid Region.
2. Depressors of Os hyoideum and
Larynx.
Sterno-hyoid.
Sterno-thyroid.
Thyro-hyoid.
Omo-hyoid.
Supra-hyoid Region.
3. Elevators of Os hyoideum and Larynx.
Digastric.
Stylo-hyoid.
Mylo-hyoid.
Genio-hyoid.
Lingual Region.
4. Muscles of the Tongue.
Genio-hyo-glossus.
Hyo-glossus.
Chondro-glossus.
Stylo-glossus.
Palato-glossus.
5. Muscles of the Pharynx.
Inferior constrictor.
Middle constrictor.
Superior constrictor.
Stylo-pharyngeus.
Palato-pharyngeus.
6. Muscles of the Soft Palate.
Levator palati.
Tensor palati.
Azygos uvula?.
Palato-glossus.
Palato-pharyngeus.
Salpingo-pharyngeus.
7. Muscles of the Anterior Vertebral
Region.
Rectus capitis anticus major.
Rectus capitis anticus minor.
Rectus capitis lateralis.
Longus colli.
8. Muscles of the Lateral Vertebral
Region.
Scalenus anticus.
Scalenus medius.
Scalenus posticus.
9. Muscles of the Larynx.
Included in description of the
Larynx.
1. The Superficial Cervical Region.
Platysma myoides. Sterno-cleido-mastoid.
Dissection. — A block having been placed at the back of the neck, and the face turned to
the side opposite that to be dissected, so as to place the parts upon the stretch, make two trans-
verse incisions: one from the chin, along the margin of the lower jaw, to the mastoid process,
and the other along the upper border of the clavicle. Connect these by an oblique incision
made in the course of the Sterno-mastoid muscle, from the mastoid process to the sternum; the
two flaps of integument having been removed in the direction shown in Fig. 258, the superficial
fascia will be exposed.
Superficial Cervical Fascia. — The superficial cervical fascia is a thin, apon-
eurotic lamina which is hardly demonstrable as a separate membrane. Beneath
it is found the Platysma myoides muscle.
The Platysma Myoides (m. platysma) (Fig. 260) is a broad, thin plane of mus-
cular fibres placed immediately beneath the superficial fascia on each side of the
neck. It arises by thin, fibrous bands from the fascia covering the upper part of the
Pectoral and Deltoid muscles ; its fibres pass over the clavicle and proceed obliquely
upward and inward along the side of the neck. The anterior fibres interlace,
below and behind the symphysis menti, with the fibres of the muscle of the oppo-
site side ; the posterior fibres pass over the lower jaw, some of them being attached
to the bone below the external oblique line, others passing on to be inserted into
the skin and subcutaneous tissue of the lower part of the face, many of these fibres
blending with the muscles about the angle and lower part of the mouth. Some-
THE SUPERFICIAL CER VICAL REGION 389
times fibres can be traced to the Zygomatic muscles or to the margin of the
Orbicularis oris. Beneath the Platysma the external jugular vein may be seen
descending in a line from the angle of the jaw to the middle of the clavicle.
Relations. — By its external surface, with the integument, to which it is united
more closely below than above; by its internal surface, with the Pectoralis major
and Deltoid, and with the clavicle. In the neck, with the external and anterior
jugular veins, the deep cervical fascia, the superficial branches of the cervical
plexus, the Sterno-mastoid, Sterno-hyoid, Omo-hyoid, and Digastric muscles;
behind the Sterno-mastoid muscle it covers in the posterior triangle of the neck.
On the face it is in relation with the parotid gland, the facial artery and vein,
and the Masseter and Buccinator muscles.
Nerves. — The lower division of the facial nerve chiefly innervates this muscle,
and superficial branches from the cervical plexus also reach it.
Action. — The Platysma myoides produces a slight wrinkling of the surface of
the skin of the neck, in an oblique direction, when the entire muscle is brought
into action. Its anterior portion, the thickest part of the muscle, depresses the
lower jaw; it also serves to draw down the lower lip and angle of the mouth on
each side, being one of the chief agents in the expression of melancholy. In the
pressure upon the blood-vessels of the neck induced by strong inspiratory effort,
this muscle draws away the skin and fascia, and by so doing, greatly diminishes
the pressure on the veins.
Deep Cervical Fascia (fascia colli) (Fig. 268). — The deep cervical fascia
lies under cover of the Platysma myoides muscle and constitutes a complete
investment for the neck. It also forms a sheath for the carotid vessels, and, in
addition, is prolonged deeply in the shape of certain processes or lamellae, which
come into close relation with the structures situated in front of the vertebral column.
The investing portion of the fascia is attached, behind, to the ligamentum
nuchae and to the spine of the seventh cervical vertebra. Along this line it splits
to enclose the Trapezius muscle, at the anterior border of which the two enclosing
lamellae unite and form a strong membrane, which extends forward so as to roof
in the posterior triangle of the neck. Along the hinder edge of the Sterno-mastoid
the membrane divides to enclose this muscle, at the anterior edge of which it once
more forms a single lamellae, which roofs in the anterior triangle of the neck,
and, reaching forward to the middle line, is continuous with the corresponding
part from the opposite side of the neck. In the middle line of the neck it is attached
to the symphysis menti and to the body of the hyoid bone.
Above, the fascia is attached to the superior curved line of the occiput, to the
mastoid process of the temporal, and to the whole length of the body of the jaw.
Opposite the angle of the jaw the fascia is very strong, and binds the anterior
edge of the Sterno-mastoid firmly to that bone. Between the jaw and the mastoid
process it ensheaths the parotid gland — the layer which covers the gland extending
upward under the name of the parotid fascia to be fixed to the zygomatic arch.
The parotid fascia is prolonged forward to cover the masseter muscle, the masse-
teric fascia. From the layer which passes under the parotid a strong band,
the stylo-mandibular ligament, reaches from the styloid process to the angle of
the jaw. The parotid and masseteric fasciae constitute the fascia parotideo-
masseterica.
Below, the cervical fascia is attached to the acromion process, the clavicle, and
to the manubrium sterni. Some little distance above the last-named point, how-
ever, it splits into two layers, superficial and deep. The former is attached to
the anterior border of the manubrium, the latter to its posterior border and to
the interclavicular ligament. Between these two layers is a slit-like interval, the
suprasternal space or space of Burns (spatium supr aster nale). It contains a small
quantity of areolar tissue, and sometimes a lymphatic gland; the lower portions
390
THE MUSCLES AND FASCIAE
of the anterior jugular veins and their transverse connecting branch; and also
the sternal heads of the Sterno-mastoid muscles.
The fascia which lines the deep aspect of the Sterno-mastoid gives off certain
important processes, viz. : (1) A process to envelop the tendon of the Omo-hyoid,
and bind it down to the sternum and first costal cartilage. (2) A strong sheath,
the carotid sheath, for the large vessels of the neck, enclosed within which are the
carotid artery, internal jugular vein, the vagus, and descendens hypoglossi nerves.
(3) The prevertebral fascia (fascia praevertebralis), which extends inward behind
SPACE BETWEEN THE
TWO LAYERS OF FASCIA
CESOPHAGUS
PREVERTEBRAL
FASCIA
STERNOTHYROID
DEEP FASCIA OF NECK
STERNOHYOIO
OMOHYOID
COMMON CAROTID
ARTERY
DESCENDENS HYPO-
iLOSSI NERVE
PNEUMOGASTRIC
'NERVE
^LYMPHATIC
GLANDS
.SYMPATHETIC
NERVE
.PHRENIC
NERVE
.INTERNAL
JUGULAR
SUPERFICIAL
FASCIA OF
NECK
FIG. 268.— Transverse section through the neck at the level of the seventh cervical vertebra. (Spalteholz.)
the carotid vessels, where it assists in forming their sheath, and passes in front
of the prevertebral muscles.. It thus forms the posterior limit of a fibrous com-
partment which contains the larynx and trachea, the thyroid gland, and the
pharynx and oesophagus. The prevertebral fascia is fixed above to the base of
the skull, while below it is continued into the thorax in front of the Longus colli
muscles. Parallel to the carotid vessels and along their inner aspect it gives off
a thin lamina, the bucco-pharyngeal fascia (fascia buccopharyngea) , which closely
invests the constrictor muscles of the pharynx, and is continued forward from
the Superior constrictor on to the Buccinator. It is attached to the prever-
THE SUPERFICIAL CERVICAL REGION 391
tebral layer by loose connective tissue only, and thus an easily distended space,
the retro-pharyngeal space (xp:itium retropharynged),is found between them. This
space is limited above by the base of the skull, while below it extends behind the
u-sophagus into the thorax, where it is continued into the posterior mediastinum.
The prevertebral fascia is prolonged downward and outward behind the carotid
vessels and in front of the Scaleni muscles, and forms a sheath for the brachial
plexus of nerves and for the subclavian vessels in the posterior triangle of the neck,
and, continuing under the clavicle as the axillary sheath, is attached to the deep
surface of the costo-coracoid membrane. Immediately above the clavicle an
areolar space exists between the investing layer and the sheath of the subclavian
vessels, and in it are found the lower part of the external jugular vein, the descend-
ing clavicular nerves, the suprascapular and transversalis colli vessels, and the
posterior belly of the Omo-hyoid muscle. This space extends downward behind
the clavicle, and is limited below by the fusion of the costo-coracoid membrane
with the anterior wall of the axillary sheath. (4) The pre-tracheal fascia, which
extends inward in front of the carotid vessels, and assists in forming the carotid
sheath. It is further continued behind the Depressor muscles of the hyoid bone,
and, after enveloping the thyroid body, is prolonged in front of the trachea to
meet the corresponding layer of the opposite side. Above, it is fixed to the hyoid
bone, while below it is carried downward in front of the trachea and large vessels
at the root of the neck, and ultimately blends with the fibrous pericardium.
Surgical Anatomy. — The cervical fascia is of considerable importance from a surgical
point of view. As will be seen from the foregoing description, it may be divided into three
layers: (1) A superficial layer; (2) a layer passing in front of the trachea, and forming with
the superficial layer a sheath for the depressors of the hyoid bone; (3) a prevertebral layer
passing in front of the bodies of the cervical vertebrae, and forming with the second layer a
space in which are contained the trachea, oesophagus, etc. The superficial layer forms a com-
plete investment for the neck. It is attached behind to the ligamentum nuchae and the spine
of the seventh cervical vertebra; above it is attached to the external occipital protuberance, to
the superior curved line of the occiput, to the mastoid process, to the zygoma and the lower
jaw; below it is attached to the manubrium sterni, the clavicle, the acromion process, and
the spine of the scapula; in front it blends with the fascia of the opposite side. This layer
opposes the extension of abscesses or new-growths toward the surface, and pus forming beneath
it has a tendency to extend laterally. If pus is in the posterior triangle, it might extend
backward under the Trapezius, forward under the Sterno-mastoid, or downward under the
clavicle for some distance, until stopped by the junction of the cervical fascia to the Costo-
coracoid membrane. If the pus is contained in the anterior triangle, it might find its way into
the anterior mediastinum, being situated in front of the layer of fascia which passes down into
the thorax to become continuous with the pericardium; but owing to the lesser density and
thickness of the fascia in this situation it more frequently finds its way through it and points
above the sternum. The second layer of fascia is connected above with the hyoid bone. It
passes down beneath the depressors and in front of the thyroid body and trachea to become
continuous with the fibrous layer of the pericardium. Laterally it invests the great vessels of
the neck and is connected with the superficial layer beneath the Sterno-mastoid. Pus forming
beneath this layer would in all probability find its way into the posterior mediastinum. The
third layer (the prevertebral fascia) is connected above to the base of the skull. Pus forming
beneath this layer, in cases, for instance, of caries of the bodies of the cervical vertebrae, might
extend toward the posterior and lateral part of the neck and point in this situation, or might
perforate this layer of fascia and the pharyngeal fascia and point into the pharynx (retro-
pharyngeal abscess).
In cases of cut throat the cervical fascia is of considerable importance. When the wound
involves only the superficial layer the injury is usually trivial, the only special danger being
injury to the external jugular vein, and the only special complication being diffuse cellulitis.
But where the second of the two layers has been opened up, important structures may have
been injured, which may lead to serious results.
It may be worth while 'mentioning that in Burns's space is contained the sternal head of
origin of the Sterno-mastoid muscle, so that this space is opened in division of this tendon.
The anterior jugular vein is also contained in the same space.
The Sterno-mastoid or Sterno-cleido-mastoid (m. sternocleidomastoideus)
(Fig. 269) is a large, thick muscle, which passes obliquely across the side of the
392
THE MUSCLES AND FASCIA
neck, being enclosed between two layers of the deep cervical fascia. It is thick
and narrow at its central part, but is broader and thinner at each extremity. It
arises, by two heads, from the sternum and clavicle. The sternal portion is a
rounded fasciculus, tendinous in front, fleshy behind, which arises from the
upper and anterior part of the first piece of the sternum, and is directed
upward, outward, and backward. 'The clavicular portion arises from the inner
third of the superior border and anterior surface of the clavicle, being com-
posed of fleshy and aponeurotic fibres; it is directed almost vertically upward.
These two portions are separated from one another, at their origin, by a triangular
cellular interval, but become gradually blended, below the middle of the neck/
into a thick, rounded muscle, which is inserted, by a strong tendon, into the outer
surface of the mastoid process of the temporal bone, from its apex to its superior
border, and by a thin aponeurosis into the outer half of the superior curved line of
the occipital bone. The Sterno-mastoid varies much in its extent of attachment
to the clavicle: in one case the clavicular may be as narrow as the sternal portion;
in another, the former may be as much as three inches in breadth. When the
clavicular origin is broad, it is occasionally subdivided into numerous slips separ-
ated by narrow intervals. More rarely, the corresponding margins of the Sterno-
mastoid and Trapezius have been found in contact. In the application of a ligature
FIG. 269. — Muscles of the neck and boundaries of the triangles.
to the third part of the subclavian artery it will be necessary, where the Sterno-
mastoid and Trapezius come close together, to divide a portion of one or of both.
This muscle divides the quadrilateral space at the side of the neck into two
triangles, an anterior and a posterior. The boundaries of the anterior triangle
are, in front, the median line of the neck; above, the lower border of the body of
the jaw, and an imaginary line drawn from the angle of the jaw to the mastoid
process; behind, the anterior border of the Sterno-mastoid muscle. The apex of
the triangle is at the upper border of the sternum. The boundaries of the posterior
THE INFRA-HYOID REGION 393
triangle are, in front, the posterior border of the Sterno-mastoid ; below, the middle
third of the clavicle ; behind, the anterior margin of the Trapezius.1 The apex corre-
sponds with the meeting of the Sterno-mastoid and Trapezius on the occipital bone.
Relations. — By its superficial surface, with the integument and Platysma,
from which it is separated by the external jugular vein, the superficial branches
of the cervical plexus, and the anterior layer of the deep cervical fascia. By its
deep surface it is in relation with the Sterno-clavicular articulation; a process of
the deep cervical fascia; the Sterno-hyoid, Sterno-thyroid, Omo-hyoid, posterior
belly of the Digastric, Levator anguli scapulae, Splenius and Scaleni muscles;
common carotid artery, internal and anterior jugular veins, commencement of the
internal and external carotid arteries, the occipital, subclavian, transversalis colli,
and suprascapular arteries and veins; the phrenic, vagus, hypoglossal, descen-
dens and communicans hypoglossi nerves; the accessory nerve, which pierces
its upper third; the cervical plexus, parts of the thyroid and parotid gLnds, and
deep lymphatic glands.
Nerves. — The Sterno-cleido-mastoid is supplied by the accessory nerve and
deep branches of the cervical plexus.
Actions. — When only one Sterno-mastoid muscle acts, it draws the head toward
the shoulder of the same side, assisted by the Splenius and the Obliquus capitis
inferior of the opposite side. At the same time it rotates the head so as to carry
the face toward the opposite side. When the two muscles act together they
flex the head upon the neck. If the head is fixed, the two muscles assist in
elevating the thorax in forced inspiration.
Surface Form. — The anterior edge of the muscle forms a very prominent ridge beneath the
skin, which it is important to notice, as it forms a guide to the surgeon in making the necessary
incisions for ligature of the common carotid artery and for cesophagotomy.
Surgical Anatomy. — The relations of the sternal and clavicular parts of the Sterno-mastoid
should be carefully examined, as the surgeon is sometimes required to divide one or both portions
of the muscle in wry-neck (torticollis). One variety of this distortion is produced by spasmodic
contraction or rigidity of the Sterno-mastoid; the head being carried down toward the shoulder
of the same side, and the face turned to the opposite side and fixed in that position. When there
is permanent shortening, subcutaneous division of the muscle is resorted to by some surgeons.
This is performed by introducing a tenotomy knife beneath it, close to its origin, and dividing
it from behind forward whilst the muscle is put well upon the stretch. There is seldom any
difficulty in dividing the sternal portion by making a puncture on the inner side of the tendon,
and then pushing a blunt tenotome behind it, and cutting forward. In dividing the clavicular
portion care must be taken to avoid wounding the external jugular vein, which runs parallel
with the posterior border of the muscle in this situation, or the anterior jugular vein, which
crosses beneath it. If the external jugular vein lies near the muscle, it is safer to make the
first puncture at the outer side of the tendon, and introduce a blunt tenotome from without
inward. Many surgeons prefer dividing the muscle by open incision, because by this method
all of the contracted fibres, muscular and facial, can be certainly and safely divided. An incision
is made over the origin of the muscle, the origin is exposed, a director is passed underneath it,
and it is then divided. With care and attention to asepsis this plan of treatment is devoid of
risk, and in this way the accidental division of vessels can be avoided. Some of the fibres of
the Sterno-mastoid muscle are occasionally torn during birth, especially in breech presenta-
tions; this is accompanied by hemorrhage and formation of a swelling within the substance of
the muscle. This by some is believed to be one of the causes of wry-neck, the scar tissue
which is formed contracting and shortening the muscle.
2. The Infra-hyoid Region (Figs. 269, 270).
DEPRESSORS OF THE Os HYOIDEUM AND LARYNX.
Sterno-hyoid. Thyro-hyoid.
Sterno-thyroid. Omo-hyoid.
Dissection. — The muscles in this region may be exposed by removing the deep fascia from the
front of the neck. In order to see the entire extent of the Omo-hyoid it is necessary to divide
the sterno-mastoid at its centre, and turn its ends aside, and to detach the Trapezius from the
clavicle and scapula. This, however, should not be done until the Trapezius has been dissected.
1 The anatomy of these triangles will be more exactly described with that of the vessels of the neck. — ED. of
15th English edition.
THE MUSCLES AND FASCIA
The Sterno-hyoid (m. sternohyoideus) is a thin, narrow, ribbon-like muscle,
which arises from the inner extremity of the clavicle, the posterior sterno-
clavicular ligament, and the upper and posterior part of the first piece of the
sternum ; passing upward and inward, it is inserted, by short, tendinous fibres,
into the lower border of the body of the hyoid bone. This muscle is separated,
below, from its fellow by a considerable interval ; but the two muscles come into
contact with one another in the middle of their course, and from this upward
lie side by side. It sometimes presents, immediately above its origin, a trans-
verse tendinous intersection, like those in the Rectus abdominis. As a rule,
two bursse, the sterno-hyoid bursse (bursae sternokyoidii) , lie between the crico-
thyroid membrane, on one hand, and the Sterno-hyoid muscle and the cervical
fascia, on the other. Sometimes there is one large median bursa instead of two
lateral bursse. Not unusually there is no bursa at all.
Relations. — By its superficial surface, below, with the sternum, the sternal end
of the clavicle, and the Sterno-mastoid ; and above, with the Platysma and deep
cervical fascia; by its deep surface, with the Sterno-thyroid, Crico-thyroid, and
Symphysis
of jaw.
FIG. 270. — Muscles of the neck. Anterior view.
Thyro-hyoid muscles, the thyroid gland, the superior thyroid vessels, the thyroid
cartilage, the crico-thyroid and thyro-hyoid membranes.
The Sterno-thyroid (m. sternothyreoideus) is situated beneath the preceding
muscle, but is shorter and wider than it. It arises from the posterior surface of
the first piece of the sternum, below the origin of the Sterno-hyoid, and from the
edge of the cartilage of the first rib, occasionally of the second rib also, and is
inserted into the oblique line on the side of the ala of the thyroid cartilage.
This muscle is in close contact with its fellow at the lower part of the neck, and
is occasionally traversed by a transverse or oblique tendinous intersection, like
those in the Rectus abdominis.
THE INFRA-HYOID REGION 395
Relations. — By its anterior surface, with the Stern o-hyoid, Omo-hyoid, and
Sterno-mastoid ; by its posterior surface, from below upward, with the trachea,
vena innominata, common carotid (and on the right side the arteria innominata),
the thyroid gland and its vessels, and the lower part of the larynx and pharynx.
The inferior thyroid vein lies along its inner border, a relation which it is impor-
tant to remember in the operation of tracheotomy. On the left side the deep
surface of the muscle is in relation to the o?sophagus.
The Thyro-hyoid (m. ihyreohyoideus) is a small, quadrilateral muscle appear-
ing like a continuation of the Sterno-thyroid. It arises from the oblique line on
the side of the thyroid cartilage, and passes vertically upward to be inserted into
the lower border of the body and greater cornu of the hyoid bone. The thyro-
hyoid bursae (bursae thyreohyoidii) lie inferior to the greater cornua of the hyoid
bone and upon the thyro-hyoid membrane. There is one bursa on each side
beneath the corresponding Thyro-hyoid muscle.
Relations. — By its external surface, with the Sterno-hyoid and Omo-hyoid
muscles; by its internal surface, with the thyroid cartilage, the thyro-hyoid mem-
brane, and the superior laryngeal vessels and nerve.
The Omo-hyoid (m. omohyoideus) passes across the side of the neck, from
the scapula to the hyoid bone. It consists of two fleshy bellies, united by a
central tendon. It arises from the upper border of the scapula, and occasionally
from the transverse ligament which crosses the suprascapular notch, its extent of
attachment to the scapula varying from a few lines to an inch. From this origin
the posterior belly (venter inferior) forms a flat, narrow fasciculus, which inclines
forward and slightly upward across the lower part of the neck, behind the Sterno-
mastoid muscle, where it becomes tendinous; it then changes its direction, forming
an obtuse angle, and terminates in the anterior belly (venter superior), which
passes almost vertically upward, close to the outer border of the Sterno-hyoid,
to be inserted into the lower border of the body of the hyoid bone, just external to
the insertion of the Sterno-hyoid. The central tendon of this muscle, which varies
much in length and form, is held in position by a process of the deep cervical
fascia, which includes it in a sheath. This process is prolonged down, to be
attached to the clavicle and first rib. It is by this means that the angular form of
the muscle is maintained.
This muscle subdivides each of the two large triangles at the side of the neck
into two smaller triangles; the two posterior ones being the posterior superior or
occipital triangle, and the posterior inferior or subclavian triangle; the two anterior,
the anterior superior or superior carotid triangle, and the anterior inferior or inferior
carotid triangle.
Relations. — By its superficial surface, with the Trapezius, the Sterno-mastoid,
deep cervical fascia, Platysma, and integument; by its deep surface, with the
Scaleni muscles, phrenic nerve, lower cervical nerves, which go to form the brachial
plexus, the suprascapular vessels and nerve, sheath of the common carotid artery
and internal jugular vein, the Sterno-thyroid and Thyro-hyoid muscles.
Nerves. — The Thyro-hyoid is supplied by the hypoglossal; the other muscles
of this group by branches from the loop of communication between the descendens
and communicans hypoglossi.
Actions. — These muscles depress the larynx and hyoid bone, after they have
been drawn up with the pharynx in the act of deglutition. The Omo-hyoid
muscles not only depress the hyoid bone, but carry it backward and to one side.
It is concerned especially in prolonged inspiratory efforts; for by tensing the
lower part of the cervical fascia it lessens the inward suction of the soft parts,
wrhich would otherwise compress the great vessels and the apices of the lungs.
This action is synergistic with that of the Platysma. The Thyro-hyoid may act
as an elevator of the thyroid cartilage when the hyoid bone ascends, drawing
396 THE MUSCLES AND FASCIA
upward the thyroid cartilage, behind the hyoid bone. The Sterno-thyroid acts as
a depressor of the thyroid cartilage.
3. The Supra-hyoid Region (Figs. 269, 270).
ELEVATORS OF THE Os HYOIDEUM — DEPRESSORS OF THE LOWER JAW.
Digastric. Mylo-hyoid.
Stylo-hyoid. Genio-hyoid.
Dissection. — To dissect these muscles a block should be placed beneath the back of the
neck, and the head drawn backward and retained in that position. On the removal of the deep
fascia the muscles are at once exposed.
The Digastric (TO. digastricus) consists of two fleshy bellies united by an inter-
mediate, rounded tendon. It is a small muscle, situated below the side of the
body of the lower jaw, and extending, in a curved form, from the side of the
head to the symphysis of the jaw. The posterior belly (venter posterior), longer
than the anterior, arises from the digastric groove on the inner side of the mas-
toid process of the temporal bone, and passes downward, forward, and inward.
The anterior belly (venter anterior) arises from a depression on the inner side
of the lower border of the jaw, close to the symphysis, and passes downward
and backward. The two bellies terminate in the central tendon which per-
forates the Stylo-hyoid, and is held in connection with the side of the body
and the greater cornu of the hyoid bone by a fibrous loop, lined by a synovial
membrane. A broad aponeurotic layer is given off from the tendon of the
Digastric on each side, which is attached to the body and great cornu of the
hyoid bone: this is termed the supra-hyoid aponeurosis. It forms a strong layer
of fascia between the anterior portion of the two muscles, and a firm investment
for the other muscles of the supra-hyoid region which lie deeper.
The Digastric muscle divides the anterior superior triangle of the neck into
two smaller triangles; the upper, or submaxillary triangle, being bounded, above, by
the lower border of the body of the jaw, and a line drawn from its angle to the
mastoid process; below, by the posterior belly of the Digastric and the Stylo-
hyoid muscles; in front, by the middle line of the neck and the anterior belly of the
Digastric, the lower or superior carotid triangle being bounded above by the poste-
rior belly of the Digastric, behind by the Sterno-mastoid, below by the anterior
belly of the Omo-hyoid.
Relations. — By its superficial surface, with the mastoid process, the Platysma,
Sterno-mastoid, part of the Splenius, Trachelo-mastoid, and Stylo-hyoid muscles,
and the parotid gland. By its deep surface, the anterior belly lies on the Mylo-
hyoid; the posterior belly oh the Stylo-glossus, Stylo-pharyngeus, and Hyo-glossus
muscles, the external carotid artery and its occipital, lingual, facial, and ascending
pharyngeal branches, the internal carotid artery, internal jugular vein, and hypo-
glossal nerve.
The Stylo-hyoid (m. stylohyoideus) is a small, slender muscle, lying in front
of, and above, the posterior belly of the Digastric. It arises from the back and
outer surface of the styloid process of the temporal bone, near the base; and,
passing downward and forward, is inserted into the body of the hyoid bone,
just at its junction with the greater cornu, and immediately above the Omo-
hyoid. This muscle is perforated, near its insertion, by the tendon of the
Digastric.
Relations. — By its superficial surface above with the parotid gland and deep
cervical fascia; below it is superficial, being situated immediately beneath the deep
cervical fascia. By its deep surface, with the posterior belly of the Digastric, the
external carotid artery, with its lingual and facial branches, the Hyo-glossus
muscle, and the hypoglossal nerve.
THE 8UPRA-HYOID REGION
397
The Stylo-hyoid Ligament (ligamentum stylohyoideus) . — In connection witli the
Stylo-hyoid muscle may be described a ligamentous band, the styh-hyoid ligament.
It is a fibrous cord, often containing a little cartilage in its centre, which continues
the styloid process down to the hyoid bone, being attached to the tip of the former
and the small cornu of the latter. It is often more or less ossified, and in many
animals forms a distinct bone, the epihyal.
The anterior belly of the Digastric should be removed, in order to expose the next muscle.
The Mylo-hyoid (m. mylohyoideus) (Fig. 271) is a flat, triangular muscle,
situated immediately beneath the anterior belly of the Digastric, and forming,
with its fellow of the opposite side, a muscular floor for the cavity of the mouth.
It arises from the whole length of the mylo-hyoid ridge of the lower jaw, extend-
ing from the symphysis in front to the last molar tooth behind. The posterior
fibres pass inward and slightly downward, to be inserted into the body of the
hyoid bone. The middle and anterior fibres are inserted into a median fibrous
raphe, extending from the symphysis of the lower jaw to the hyoid bone, where
they join at an angle with the fibres of the opposite muscle. The median raphe
HYOID BONE
FIG. 271. — Mylo-hyoid muscle. (Poirier and Charpy.)
is sometimes wanting; the muscular fibres of the two sides are then directly
continuous with one another.
Relations. — By its cutaneous or under surface, with the Platysma, the anterior
belly of the Digastric, the supra-hyoid aponeurosis, the submaxillary gland, sub-
mental vessels, and mylo-hyoid vessels and nerve; by its deep or superior surface,
with the Genio-hyoid, part of the Hyo-glossus and Stylo-glossus muscles, the hypo-
glossal and lingual nerves, the submaxillary ganglion, the sublingual gland, the
deep portion of the submaxillary gland, and Wharton's duct; the sublingual and
ranine vessels, and the buccal mucous membrane.
Dissection. — The Mylo-hyoid should now be removed, in order to expose the muscles which
lie beneath; this is effected by reflecting it from its attachments to the hyoid bone and jaw, and
separating it by a vertical incision from its fellow of the opposite side.
The Genio-hyoid (m. geniohyoideus) (Fig. 272) is a narrow, slender muscle,
situated immediately beneath1 the inner border of the preceding. It arises from
the inferior genial tubercle on the inner side of the symphysis of the jaw, and
1 This refers to the depth of the muscles from the skin in the order of dissection,
the body the Genio-hyoid is above the Mylo-hyoid.
In the erect position of
398
THE MUSCLES AND FASCIAE
passes downward and backward, to be inserted into the anterior surface of the
body of the hyoid bone. This muscle lies in close contact with its fellow of the
opposite side, and increases slightly in breadth as it descends.
Relations. — It is covered by the Mylo-hyoid and lies along the lower border
of the Genio-hyo-glossus.
Nerves. — The anterior belly of the Digastric is supplied by the mylo-hyoi<i
branch of the inferior dental; its posterior belly, by the facial; the Stylo-hyoid
is supplied by the facial; the Mylo-hyoid, by the mylo-hyoid branch of the
inferior dental; the Genio-hyoid, by the hypoglossal.
Actions. — This group of muscles performs two very important actions. *They
raise the hyoid bone, and with it the base of the tongue, during the act of degluti-
tion; or, when the hyoid bone is fixed by its depressors and those of the larynx,
they depress the lower jaw. During the first act of deglutition, when the mass
is being driven from the mouth into the pharynx, the hyoid bone, and with it the
tongue, is carried upward and forward by the anterior belly of the Digastric, the
Mylo-hyoid, and Genio-hyoid muscles. In the second act, when the mass is pass-
FIG. 272.— Muscles of the tongue. Left side.
ing through the pharynx, the direct elevation of the hyoid bone takes place by the
combined action of all the muscles; and after the food has passed, the hyoid bone
is carried upward and backward by the posterior belly of the Digastric and Stylo-
hyoid muscles, which assist in preventing the return of the morsel into the mouth.
4. The Lingual Region (Figs. 272, 273).
Genio-hyo-glossus. Stylo-glossus.
Hyo-glossus. Palato-glossus.
Chondro-glossus.
THE LINGUAL REGION 399
Dissection. — After completing the dissection of the preceding muscles, saw through the
lower jaw just external to the syraphysis. Then draw the tongue forward, and attach it, by a
stitch, to the nose; when its muscles, which are thus put on a stretch, may be examined.
The Genio-hyo-glossus (m. genioglossus) has received its name from its triple
attachment to the jaw, hyoid bone, and tongue, but it is better to name it the
Genio-glossus, since its attachment to the hyoid bone is very slight or altogether
absent. It is a flat, triangular muscle, placed vertically on either side of the
middle line, its apex corresponding with its point of attachment to the lower jaw, its
base with its insertion into the tongue and hyoid bone. It arises by a short tendon
from the superior genial tubercle on the inner side of the symphysis of the jaw, im-
mediately above the Genio-hyoid ; from this point the muscle spreads out in a fan-
like form, a few of the inferior fibres passing downward, to be attached by a thin
aponeurosis into the upper part of the body of the hyoid bone, a few fibres passing
between the Hyo-glossus and Chondro-glossus to blend with the Constrictor mus-
cles of the pharynx; the middle fibres passing backward, and the superior ones
upward and forward, to enter the whole length of the under surface of the tongue,
from the base to the apex. The two muscles lie on either side of the median plane;
behind they are quite distinct from each other, and are separated at their insertion
into the under surface of the tongue by a tendinous raphe, which extends through
the middle of the organ; in front, the two muscles are more or less blended : distinct
fasciculi are 'to be seen passing off from one muscle, crossing the middle line, and
intersecting with bundles of fibres derived from the muscle on the other side.
Relations. — By its internal surface it is in contact with its fellow of the opposite
side; by its external surface, with the Inferior lingualis, the Hyo-glossus, the lin-
gual artery and hypoglossal nerve, the lingual nerve, and sublingual gland; by its
upper border, with the mucous membrane of the floor of the mouth (fraenum
linguae); by its lower border with the Genio-hyoid.
The Hyo-glossus (m. hyoglossus) is a thin, flat, quadrilateral muscle which arises
from the side of the body and whole length of the greater cornu of the hyoid bone,
and passes almost vertically upward to enter the side of the tongue, between the
Stylo-glossus and Lingualis. Those fibres of this muscle which arise from the
body are directed upward and backward, overlapping those arising from the
greater cornu, which are directed upward and forward.
Relations. — By its external surface, with the Digastric, the Stylo-hyoid, Stylo-
glossus, and Mylo-hyoid muscles, the submaxillary ganglion, the lingual and hypo-
glossal nerves, Wharton's duct, the ranine vein, the sublingual gland j and the deep
portion of the submaxillary gland. By its deep surface, with the Stylo-hyoid liga-
ment, the Genio-hyo-glossus, Lingualis, and Middle constrictor, the lingual vessels
and the glosso-pharyngeal nerve.
The Chondro-glossus (TO. chondroglossus) is a distinct muscular slip, though it is
sometimes described as a part of the Hyo-glossus, from which, however, it is sepa-
rated by the fibres of the Genio-hyo-glossus, which pass to the side of the pharynx.
It is about three-quarters to an inch in length, and arises from the inner side and
base of the lesser cornu and contiguous portion of the body of the hyoid bone,
and passes directly upward to blend with the intrinsic muscular fibres of the tongue,
between the Hyo-glossus and Genio-hyo-glossus. A small slip of muscular fibre
is occasionally found, arising from the cartilage triticea in the thyro-hyoid ligament,
and passing upward and forward to enter the tongue with the hindermost fibres of
the Hyo-glossus.
The Stylo-glossus (TO. styloglossus) , the shortest and smallest of the three styloid
muscles, arises from the anterior and outer side of the styloid process, near its apex,
and from the stylo-mandibular ligament, to which its fibres, in most cases, are
attached by a thin aponeurosis. Passing downward and forward between the inter-
nal and external carotid arteries, and becoming nearly horizontal in its direction,
it divides upon the side of the tongue into two portions : one longitudinal, which
400
THE MUSCLES AND FASCIAE
enters the side of the tongue near its dorsal surface, blending with the fibres of the
Lingualis in front of the Hyo-glossus; the other oblique, which overlaps the
Hyo-glossus muscle and decussates with its fibres.
Relations. — By its external surface, from above downward, with the parotid
gland, the Internal pterygoid muscle, the lingual nerve, and the mucous membrane
of the mouth; by its internal surface, with the tonsil, the Superior constrictor, and
the Hyo-glossus muscle.
The Palato-glossus or Constrictor Isthmi Faucium (m. glossopalatinus) ,
although it is one of the muscles of the tongue, serving to draw its base upward
during the act of deglutition, is more nearly associated with the soft palate, both
in its situation and function ; it will consequently be described with that group of
muscles.
Nerves. — The Palato-glossus is probably innervated by the accessory nerve ,
through the pharyngeal plexus; the remaining muscles of this group, by the hypo-
glossal nerve.
Muscular Substance of the Tongue (Figs. 273 and 274). — The muscular
fibres of the tongue run in various directions. These fibres are divided into two
sets — Extrinsic and Intrinsic. The extrinsic muscles of the tongue are those
which have their origin external, and only their terminal fibres contained in the
substance of the organ. They are : the Stylo-glossus, the Hyo-glossus, the Palato-
glossus, the Genio-hyo-glossus, and part of the
Superior constrictor of the pharynx (Pharyngeo-
glossus). The intrinsic muscles are those which
are contained entirely within the tongue, and
form the greater part of its muscular struc-
ture.
CUT EDGE OF SUPERIOR LINGUALIS.
FIG. 273.-
-Muscles on the dorsum of the
tongue.
FIG. 274.- — Coronal section of tongue. Showing intrinsic
muscles, a, lingual artery; b. Inferior lingualis, cut through;
c, fibres of Hyo-glossus; d, oblique fibres of Stylo-glossus; e, in-
sertion of Transverse lingualis; /, Superior lingualis; g, papillae
to tongue; h, vertical fibres of Genio-hyo-glossus intersecting
Transverse lingualis; i, septum. (Altered from Krause.)
The tongue consists of symmetrical halves separated from each other in the
middle line by a fibrous septum (septum linguae}. Each half is composed of
muscular fibres arranged in various directions, containing much interposed fat,
and supplied by vessels and nerves.
To demonstrate the various fibres of the tongue, the organ should be subjected to
prolonged boiling, in order to soften the connective tissue; the dissection may then
be commenced from the dorsum (Figs. 273 and 274). Immediately beneath the
THE LINGUAL REGION 401
«
mucous membrane is a submucous, fibrous layer, into which the muscular fibres
which terminate on the surface of the tongue are inserted. Upon removing this,
with the mucous membrane, the first stratum of muscular fibres is exposed.
This belongs to the group of intrinsic muscles, and has been named the Superior
lingualis (ra. longitudinalis superior). It consists of a thin layer of oblique and
longitudinal fibres which arise from the submucous fibrous layer, close to the
Epiglottis, and from the fibrous septum, and pass forward and outward to the
edges of the tongue. Between its fibres pass some vertical fibres derived from
the Genio-hyo-glossus and from the vertical intrinsic muscle, which will be de-
scribed later on. Beneath this layer is the second stratum of muscular fibres,
derived principally from the extrinsic muscles. In front it is formed by the fibres
derived from the Stylo-glossus, running along the side of the tongue, and sending
one set of fibres over the dorsum which run obliquely forward and inward to the
middle line, and another set of fibres seen at a later period of the dissection, on to
the under surface of the sides of the anterior part of the tongue, which run forward
and inward, between the fibres of the Hyo-glossus, to the middle line. Behind this
layer of fibres, derived from the Stylo-glossus, are fibres derived from the Hyo-
glossus, assisted by some few fibres of the Palato-glossus. The Hyo-glossus, enter-
ing the side of the under surface of the tongue, between the Stylo-glossus and
Inferior lingualis, passes round its margin and spreads out into a layer on the dor-
sum, which occupies the middle third of the organ, and runs almost transversely
inward to the septum. It is reinforced by some fibres from the Palato-glossus;
other fibres of this muscle pass more deeply and intermingle with the next layer.
The posterior part of the second layer of the muscular fibres of the tongue is
derived from those fibres of the Hyo-glossus which arise from the lesser cornu of
thehyoid bone, and are here described as a separate muscle — theChondro-glossus.
The fibres of this muscle are arranged in a fan-shaped manner, and spread out over
the posterior third of.the tongue. Beneath this layer is the great mass of the intrin-
sic muscles of the tongue, intersected at right angles by the terminal fibres of one of
the extrinsic muscles — the Genio-hyo-glossus. This portion of the tongue is paler
in color and softer in texture than that already described, and is sometimes
designated the medullary portion in contradistinction to the firmer superficial part,
which is termed the cortical portion. It consists largely of transverse fibres, the
Transverse lingualis (m. transversus linguae), and of vertical fibres, the Vertical
lingualis (m. verticalis linguae). The Transverse lingualis forms the largest portion
of the third layer of muscular fibres of the tongue. The fibres arise from the
median septum, and pass outward to be inserted into the submucous fibrous layer
at the sides of the tongue. Intermingled with these transverse intrinsic fibres are
transverse extrinsic fibres derived from the Palato-glossus and the Superior con-
strictor of the pharynx. These transverse extrinsic fibres, however, run in the
opposite direction, passing inward toward the septum. Intersecting the transverse
fibres are a large number of vertical fibres derived partly from the Genio-hyo-
glossus and partly from intrinsic fibres, the Vertical lingualis. The fibres derived
from the Genio-hyo-glossus enter the under surface of the tongue on each side of
the median septum from base to apex. They ascend in a radiating manner to the
dorsum, being inserted into the submucous fibrous layer covering the tongue on
each side of the middle line. The Vertical lingualis is found only at the borders
of the forepart of the tongue, external to the fibres of the Genio-hyo-glossus.
Its fibres extend from the upper to the under surface of the organ, decussating
writh the fibres of the other muscles, and especially with the Transverse lingualis.
The fourth layer of muscular fibres of the tongue consists partly of extrinsic fibres
derived from the Stylo-glossus, and partly of intrinsic fibres, the Inferior lingualis
(m. longitudinalis inferior). At the sides of the under surface of the organ are
some fibres derived from the Stylo-glossus, which, as it runs forward at the side of
26
402 THE MUSCLES AND FASCIAE
the tongue, gives off fibres which, passing forward and inward between the fibres
of the Hyo-glossus, form an inferior oblique stratum which joins in front with the
anterior fibres of the Inferior lingualis. The Inferior lingualis is a longitudinal
band, situated on the under surface of the tongue, and extending from the base to
the apex of the organ. Behind, some of its fibres are connected with the body of
the hyoid bone. It lies between the Hyo-glossus and the Genio-hyo-glossus, and
in front of the Hyo-glossus it enters into relation with the Stylo-glossus, with the
fibres of which it blends. It is in relation by its under surface with the ranine
artery.
Surgical Anatomy. — The fibrous septum which exists between the two halves of the tongue
is very complete, so that the anastomosis between the two lingual arteries is not very free,
a fact often illustrated by injecting one-half of the tongue with colored size, while the other
half is left uninjected or is injected with size of a different color.
This is a point of considerable importance in connection with removal of one-half of the
tongue for cancer, an operation which is now frequently resorted to when the disease is strictly
confined to one side of the anterior portion of the tongue. If the mucous membrane is divided
longitudinally exactly in the middle line, the tongue can be split into halves along the median
raph£ without any appreciable hemorrhage, and the diseased half can then be removed.
Actions. — The movements of the tongue, although numerous and complicated,
may be understood by carefully considering the direction of the fibres of its
muscles. The Genio-hyo-glossi muscles, by means of their posterior fibres, draw
the base of the tongue forward, so as to protrude the apex from the mouth. The
anterior fibres draw the tongue back into the mouth. The whole length of these
two muscles, acting along the middle line of the tongue, draw it downward, so as to
make it concave from side to side, forming a channel along which fluids may pass
toward the pharynx, as in sucking. The Hyo-glossi muscles depress the tongue
and draw down its sides, so as to render it convex from side to side. The Stylo-
glossi muscles draw the tongue upward and backward. The Palato-glossi muscles
draw the base of the tongue upward. With regard to the intrinsic muscles, both
the Superior and Inferior linguales tend to shorten the tongue, but the former, in
addition, turn the tip and sides upward so as to render the dorsum concave, while
the latter pull the tip downward and cause the dorsum to become convex. The
Transverse lingualis narrows and elongates the tongue, and the Vertical lingualis
flattens and broadens it. The complex arrangement of the muscular fibres of
the tongue, and the various directions in which they run, give to this organ the
power of assuming the various forms necessary for the enunciation of the different
consonantal sounds; and Dr. Macalister states that "there is reason to believe
that the musculature of the tongue varies in different races owing to the hereditary
practice and habitual use of certain motions required for enunciating the several
vernacular languages."
5. The Pharyngeal Region (Figs. 275, 276, 277).
Inferior constrictor. Superior constrictor.
Middle constrictor. Stylo-pharyngeus.
Palato-pharyngeus. )
Salpingo-pharyngeus. /
Dissection (Fig. 275). — In order to examine the muscles of the pharynx, cut through the
trachea and oesophagus just above the sternum, and draw them upward by dividing the loose
areolar tissue connecting the pharynx with the front of the vertebral column. The parts being
drawn well forward, apply the edge of the saw immediately behind the styloid processes, and
saw the base of the skull through from below upward. The pharynx and mouth should then
be stuffed with tow, in order to distend its cavity and render the muscles tense and easier of
dissection.
The Inferior Constrictor (m. constrictor pharyngis inferior) , the most superficial
and thickest of the three constrictors, arises from the sides of the cricoid and
THE PHARYNGEAL REGION
403
thyroid cartilages. To the cricoid cartilage it is attached in the interval between
the Crico-thyroid muscle in front and the articular facet for the thyroid cartilage
behind. To the thyroid cartilage it is attached to the oblique line on the side of
the great ala, the cartilaginous surface behind it, nearly as far as its posterior border,
and to the inferior cornu. From these attachments the fibres spread backward and
inward, to be inserted into the fibrous raphe* in the posterior median line of the
pharynx. The inferior fibres are horizontal, and continuous with the fibres of the
oesophagus: the rest ascend, increasing in obliquity, and overlap the Middle con^
stricter.
Relations. — It is covered bv a thin membrane which surrounds the entire
pharynx, bucco-pharyngeal fascia (fascia buccopharyngea) . Behind, it is in
relation with the vertebral column
and the prevertebral fascia and mus-
cles; laterally, with the thyroid gland,
the common carotid artery, and the
Sterno-thyroid muscle; by its internal
surface, with the Middle constrictor,
the Stylo-pharyngeus, Palato-pharyn-
geus, the fibrous coat and mucous
membrane of the pharynx. The in-
ternal laryngeal nerve and the laryn-
geal branch of the Superior Thyroid
artery pass near the upper border, and
the inferior, or recurrent laryngeal
nerve, and the laryngeal branch of the
Inferior Thyroid artery, beneath the
lower border of this muscle, previous to
their entering the larynx.
The Middle Constrictor (m. constric-
tor pharyngis medius) is a flattened,
fan-shaped muscle, smaller than the
preceding. It arises from the whole
length of the upper border of the
greater cornu of the hyoid bone, from
the lesser cornu, and from the stylo-
hyoid ligament. The fibres diverge
from their origin, the lower ones de-
scending beneath the Inferior con-
strictor, the middle fibres passing
transversely, and the upper fibres ascending and overlapping the Superior con-
strictor. The muscle is inserted into the posterior median fibrous raphe", blending
in the middle line with the one of the opposite side.
Relations. — Between this muscle and the Superior constrictor are the glosso-
pharyngeal nerve, the Stylo-pharyngeus muscle and the stylo-hyoid ligament;
and between it and the Inferior constrictor is the superior laryngeal nerve.
Behind, it lies on the vertebral column, the Longus colli, and the Rectus capitis
anticus major. On each side it is in relation with the carotid vessels, the pharyn-
geal plexus, and some lymphatic glands. Near its origin it is covered by the
Hyo-glossus, the lingual vessels being placed between the two muscles. It lies
upon the Superior constrictor, the Stylo-pharyngeus, the Palato-pharyngeus, the
fibrous coat, and the mucous membrane of the larynx.
The Superior Constrictor (m. constrictor pharyngis superior) is a quadrilateral
muscle, thinner and paler than the other constrictors, and situated at the upper
part of the pharynx. It arises from the lower third of the posterior margin of the
FIG. 275. — Muscles of the pharynx. External view.
404
THE MUSCLES AND FASCIA
internal pterygoid plate and its hamular process from the contiguous portion of the
palate bone and the reflected tendon of the Tensor palati muscle, from the pterygo-
maxillary ligament, from the alveolar process above the posterior extremity of the
mylo-hyoid ridge, and by a few fibres from the side of the tongue. From these
points the fibres curve backward, to be inserted into the median raphe", being also
prolonged by means of a fibrous aponeurosis to the pharyngeal spine on the basilar
process of the occipital bone. The superior fibres arch beneath the Levator palati
and the Eustachian tube, the interval between the upper border of the muscle and
the basilar process being deficient in muscular fibres and closed by a portion
of the pharyngeai aponeurosis (fascia pharyngobasilaris) . This interval is known as
the sinus of Morgagni.
ACCESSORY BUNDLE
FROM PETROSAL PO
TION OF TEMPORAL
8TYLOID PROCESS
EXPANSION OF
STYLO-PHARYNGEUS
EXPANSION OF
PALATO-PHARYNGEUS
FIG. 276. — The muscles of the pharynx. On the right side most of the inferior constrictor has been removed,
on the left side the Digastric and Stylo-hyoid have been removed. (Spalteholz.)
Relations. — By its outer surface, with the prevertebral fascia and muscles,
the vertebral column, the internal carotid and ascending pharyngeal arteries, the
internal jugular vein and pharyngeal venous plexus, the glosso-pharyngeal, vagus,
accessory, hypoglossal, lingual, and sympathetic nerves, the Middle constrictor
THE PALATAL REGION 405
and Internal pterygoid muscles, the Styloid process, the Stylo-hyoid ligament,
and the Stylo-pharyngeus. By its internal surface, with the Palato-pharyngeus,
the tonsil, the fibrous coat and mucous membrane of the pharynx.
The Stylo-pharyngeus (m. stylopharyngeus) is a long, slender muscle, round
above, broad and thin below. It arises from the inner side of the base of the
styloid process of the temporal bone, passes down ward, along the side of the
pharynx between the Superior and Middle constrictors, and spreads out beneath
the mucous membrane, where some of its fibres are lost in the Constrictor muscles;
and others, joining with the Palato-pharyngeus, are inserted into the posterior
border of the thyroid cartilage. The glosso-pharyngeal nerve runs on the outer
side of this muscle, and crosses over it in passing forward to the tongue.
Relations. — Externally, with the Stylo-glossus muscle, the parotid gland, the
external carotid artery, and the Middle constrictor; internally, with the internal
carotid, the internal jugular vein, the Superior constrictor, Palato-pharyngeus,
and mucous membrane.
Nerves. — The Constrictors are supplied by branches from the pharyngeal
plexus. The Inferior constrictor also receives an additional" branch from the
external laryngeal nerve and one from the recurrent laryngeal. The Stylo-
pharyngeus is supplied by the glosso-pharyngeal nerve.
Actions. — When deglutition is about to be performed, the pharynx is drawn
upward and dilated in different directions, to receive the morsel propelled into it
from the mouth. The Stylo-pharyngei, which are much farther removed from
one another at their origin than at their insertion, draw the sides of the pharynx
upward and outward, and so increase its transverse diameter, its breadth in the
antero-posterior direction being increased by the larynx and tongue being carried
forward in their ascent. As soon as the morsel is received in the pharynx, the
Elevator muscles relax, the bag descends, and the Constrictors contract upon
the morsel, and convey it gradually downward into the oesophagus. Besides its
action in deglutition, the pharynx also exerts an important influence in the modu-
lation of the voice, especially in the production of the higher tones.
6. The Palatal Region (Fig. 277).
Levator palati. Palato-glossus.
Tensor palati. Palato-pharyngeus.
Azygos uvulae. Salpingo-pharyngeus.
Dissection (Fig. 277). — Lay open the pharynx from behind by a vertical incision extending
from its upper to its lower part, and partially divide the occipital attachment by a transverse
incision on each side of the vertical one; the posterior surface of the soft palate is then exposed.
Having fixed the uvula so as to make it tense, the mucous membrane and glands should be
carefully removed from the posterior surface of the soft palate, and the muscles of this part
are at once exposed.
The Levator Palati (m. levator veli palatini) is a long, thick, rounded muscle,
placed on the outer side of the posterior nares. It arises from the under surface of
the apex of the petrous portion of the temporal bone, and from the inner surface
of the cartilaginous portion of the Eustachian tube; after passing into the pharynx,
above the upper concave margin of the Superior constrictor, it passes obliquely
downward and inward, its fibres spreading out in the soft palate as far as the
middle line, where they blend with those of the opposite side.
Relations. — Externally, with the Tensor palati and Superior constrictor and
Eustachian tube; internally, with the mucous membrane of the pharynx; pos-
teriorly, with the posterior fasciculus of the Palato-pharyngeus, the Azygos uvulae,
and the mucous lining of the soft palate.
406
THE MUSCLES AND FASCIAE
The Circumflexus or Tensor Palati (m. tensor veli palatini) is a broad, thin,
ribbon-like muscle, placed on the outer side of the Levator palati, and consisting of
a vertical and a horizontal portion. The vertical portion arises by a flat lamella
from the scaphoid fossa at the base of the internal pterygoid plate; from the spine
of the sphenoid and the outer side of the cartilaginous portion of the Eustachian
tube: descending vertically between the internal pterygoid plate and the inner sur-
face of the Internal pterygoid muscle, it terminates in a tendon, which winds round
the hamular process, being retained in this situation by some of the fibres of origin
of the Internal pterygoid muscle. Between the hamular process and the tendon is
a small bursa (bursa m. tensoris veli palati) . The tendon or horizontal portion then
FIG. 277. — Muscles of the soft palate, the pharynx being laid open from behind.
passes horizontally inward, and is inserted into a broad aponeurosis, the palatine
aponeurosis, and into the transverse ridge on the horizontal portion of the palate
bone.
Relations. — Externally, with the Internal pterygoid; internally, with the Levator
palati, from which it is separated by the Eustachian tube and Superior constrictor
and with the internal pterygoid plate. In the soft palate its tendon and the pala-
tine aponeurosis are anterior to those of the Levator palati, being covered by the
Palato-glossus and the mucous membrane.
Palatine Aponeurosis.— Attached to the posterior border of the hard palate is
a thin, firm, fibrous lamella which supports the muscles and gives strength to the
soft palate. It is thicker above than below, where it becomes very thin and
difficult to define. Laterally, it is continuous with the pharyngeal aponeurosis.
THE PALATAL REGION 407
The Azygos Uvulae (m. uvulae) is not a single muscle, as would be inferred from
its name, but a pair of narrow cylindrical fleshy fasciculi placed on either side of the
median line of the soft palate. Each muscle arises from the posterior nasal spine
of the palate bone and from the contiguous tendinous aponeurosis of the soft palate,
and descends to be inserted into the uvula.
Relations. — Anteriorly, with the tendinous expansion of the Levatores palati;
behind, with the posterior fasciculus of the Palato-pharyngeus and the mucous
membrane.
The next two muscles are exposed by removing the mucous membrane from the pillars of
the fauces throughout nearly their whole extent.
The Palato-glossus or the Constrictor Isthmi Faucium (m. glossopalatinus)
is a small fleshy fasciculus, narrower in the middle than at either extremity,
forming, with the mucous membrane covering its surface, the anterior pillar of
the soft palate. It arises from the anterior surface of the soft palate on each
side of the uvula, and, passing downward, forward, and outward in front of the
tonsil, is inserted into the side of the tongue, some of its fibres spreading over
the dorsum, and others passing deeply into the substance of the organ to inter-
mingle with the Transverse lingualis. In the soft palate the fibres of this muscle
are continuous with those of the muscle of the opposite side.
The Palato-pharyngeus (m. pharyngopalatinus) is a long, fleshy fasciculus,
narrower in the middle than at either extremity, forming, with the mucous
membrane covering its surface, the posterior pillar of the soft palate. It is sepa-
rated from the Palato-glossus by an angular interval, in which the tonsil is
lodged. It arises from the soft palate by an expanded fasciculus, which is
divided into two parts by the Levator palati and Azygos uvulae. The posterior
fasciculus lies in contact with the mucous membrane, and also joins with the
corresponding muscle in the middle line; the anterior fasciculus, the thicker, lies
in the soft palate between the Levator and Tensor, and joins in the middle line
the corresponding part of the opposite muscle. Passing outward and downward
behind the tonsil, the Palato-pharyngeus joins the Stylo-pharyngeus, and is
inserted with that muscle into the posterior border of the thyroid cartilage, some
of its fibres being lost on the side of the pharynx, and others passing across the
middle line posteriorly to decussate with the muscle of the opposite side.
Relations. — In the soft palate its posterior surface is covered by mucous mem-
brane, from which it is separated by a layer of palatine glands. By its anterior
surface it is in relation with the Tensor palati. Where it forms the posterior pillar
of the fauces it is covered by mucous membrane, excepting on its outer surface. In
the pharynx it lies between the mucous membrane and the Constrictor muscles.
The Salpingo-pharyngeus arises from the inferior part of the Eustachian tube
near its orifice; it passes downward and blends with the posterior fasciculus of
the Palato-pharyngeus.
In a dissection of the soft palate from its posterior or nasal surface to its ante-
rior or oral surface, the muscles would be exposed in the following order — viz., the
posterior fasciculus of the Palato-pharyngeus, covered over by the mucous mem-
brane reflected from the floor of the nasal fossae; the Azygos uvulae; the Levator
palati; the anterior fasciculus of the Palato-pharyngeus; the aponeurosis of the
Tensor palati, and the Palato-glossus, covered over by a reflection from the oral
mucous membrane.
Nerves. — The Tensor palati is supplied by a branch from the otic ganglion;
the remaining muscles of this group are in all probability supplied by the internal
branch of the accessory, whose fibres are distributed along with certain branches
of the vagus through the pharyngeal plexus.1 It is possible, however, that the
1 Journal of Anatomy and Physiology, vol. xxiii, p. 523.
408 THE MUSCLES AND FASCIA
Levator palati may be supplied by the facial through the Petrosal branch of the
Vidian.
Actions. — During the first stage of deglutition the morsel of food is driven
back into the fauces by the pressure of the tongue against the hard palate, the
base of the tongue being, at the same time, retracted, and the larynx raised with
the pharynx, and carried forward under it. During the second stage the entrance
to the larynx is closed, not, as was formerly supposed, by the folding backward
of the epiglottis over it, but, as Anderson Stuart has shown, by the drawing
forward of the arytenoid cartilages toward the cushion of the epiglottis — a move-
ment produced by the contraction of the External thyro-arytenoid, the Arytenoid,
and Aryteno-epiglottidean muscles.
The morsel of food after leaving the tongue passes on to the posterior or laryn-
geal surface of the epiglottis, and glides along this for a certain distance;1 then
the Palato-glossi muscles, the constrictors of the fauces, contract behind the food;
the soft palate is slightly raised by the Levator palati, and made tense by the
Tensor palati; and the Palato-pharyngei, by their contraction, pull the pharynx
upward over the morsel of food, and at the same time come nearly together, the
uvula filling up the slight interval between them. By these means the food is
prevented passing into the upper part of the larynx or the posterior nares; at
the same time the latter muscles form an inclined plane, directed obliquely down-
ward and backward, along the under surface of which the morsel descends into
the lower part of the pharynx. The Salpingo-pharyngeus raises the upper and
lateral part of the pharynx — i. e., that part which is above the point where the
Stylo-pharyngeus is attached to the pharynx.
Surgical Anatomy. — The muscles of the soft palate should be carefully dissected, the rela-
tions they bear to the surrounding parts especially examined, and their action attentively studied
upon the dead subject, as the surgeon is required to divide orie or more of these muscles in the
operation of staphylorraphy. Sir W. Fergusson was the first to show that in the congenital
deficiency called deft palate the edges of the fissure are forcibly separated by the action of the
Levatores palati and Palato-pharyngei muscles, producing very considerable impediment to the
healing process after the performance of the operation for uniting their margins by adhesion ; he
consequently recommended the division of these muscles as one of the most important steps in
the operation. This he effected by an incision made with a curved knife introduced behind the
soft palate. The incision is to be half-way between the hamular process and Eustachian tube
and perpendicular to a line drawn between them. This incision perfectly accomplishes the
division of the Levator palati. The Palato-pharyngeus may be divided by cutting across the
posterior pillar of the soft palate, just below the tonsil, with a pair of blunt-pointed curved
scissors; and the anterior pillar may be divided also. To divide the Levator palati the plan
recommended by Mr. Pollock is to be greatly preferred. The soft palate being put upon the
stretch, a double-edged knife is passed through it just on the inner side of the hamular process
and above the line of the Levator palati. The handle being now alternately raised and depressed,
a sweeping cut is made along the posterior surface of the soft palate, and the knife withdrawn,
leaving only a small opening in the mucous membrane on the anterior surface. If this operation
is performed on the dead body and the parts afterward dissected, the Levator palati will be
found completely divided. In the present day, however, this division of the muscles, as part
of the operation of staphylorraphy, is not so much insisted upon. All tension is prevented by
making longitudinal incisions on either side, parallel to the cleft and just internal to the hamular
process, in such a position as to avoid the posterior palatine artery.
7. The Anterior Vertebral Region (Fig. 278).
Rectus capitis anticus major. Rectus capitis lateralis.
Rectus capitis anticus minor. Longus colli.
The Eectus Capitis Anticus Major or the Longus Capitis, broad and
thick above, narrow below, appears like a continuation upward of the Sca-
1 We now know that normal deglutition can be carried out when the epiglottis is so small that it cannot coyer
the opening into the larynx, or when it has been removed surgically. In such cases the sphincter muscles which
surround the laryngeal aperture contract during swallowing and prevent the entrance of foreign bodies into the
larynx. — ED.
THE ANTERIOR VERTEBRAL REGION
409
lenus> anticus. It arises by four tendinous slips from the anterior tubercles of
the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae, and
ascends, converging toward its fellow of the opposite side, to be inserted into the
basilar process of the occipital bone.
Relations. — By its anterior surface, with the pharynx, the sympathetic nerve,
and the sheath enclosing the internal and common carotid artery, internal jugular
vein, and vagus nerve; by its posterior surface, with the Longus colli, the Rectus
capitis anticus minor, and the upper cervical vertebrae.
FIG. 278. — The prevertebral muscles.
The Rectus Capitis Anticus Minor is a short, flat muscle, situated imme-
diately behind the upper part of the preceding. It arises from the anterior
surface of the lateral mass of the atlas and from the root of its transverse process,
and, passing obliquely upward and inward, is inserted into the basilar process
immediately behind the preceding muscle.
Relations. — By its anterior surface, with the Rectus capitis anticus major; by
its posterior surface, with the front of the occipito-atlantal articulation.
The Rectus Capitis Lateralis is a short, flat muscle, which arises from the
upper surface of the transverse process of the atlas, and is inserted into the under
surface of the jugular process of the occipital bone.
Relations. — By its anterior surface, with the internal jugular vein; by its pos-
terior surface, with the vertebral artery. On its outer side lies the occipital artery;
on its inner side, the suboccipital nerve.
The Longus Colli is a long, flat muscle, situated on the anterior surface of the
spine, between the atlas and the third thoracic vertebra. It is broad in the middle,
410
THE MUSCLES AND FASCIAE
narrow and pointed at each extremity, and consists of three portions: a superior
oblique, an inferior oblique, and a vertical portion. The superior oblique portion
arises from the anterior tubercles of the transverse processes of the third, fourth,
and fifth cervical vertebra?, and, ascending obliquely inward, is inserted by a nar-
row tendon into the tubercle on the anterior arch of the atlas. The inferior oblique
portion, the smallest part of the muscle, arises from the front of the bodies of the
first two or three thoracic vertebrae, and, ascending obliquely outward, is inserted
into the anterior tubercles of the transverse processes of the fifth and sixth cervi-
cal vertebrae. The vertical portion lies directly on the front of the spine; it arises,
below, from the front of the bodies of the upper three thoracic and lower three cer-
vical vertebrae, and is inserted above into the front of the bodies of the second,
third, and fourth cervical vertebrae.
Relations. — By its anterior surface, with the prevertebral fascia, the pharynx,,
the ossophagus, sympathetic nerve, the sheath of the great vessels of the neck,
the inferior thyroid artery, and recurrent laryngeal nerve; by its posterior surface,
with the cervical and thoracic portions of the spine. Its inner border is separated
from the opposite muscle by a considerable interval below, but they approach
each other above.
8. The Lateral Vertebral Region (Figs. 278, 279).
Scalenus anticus.
Scalenus medius.
Scalenus posticus.
The Scalenus Anticus (TO. scalenus anterior) is a conical-shaped muscle,
situated deeply at the side of the neck, behind the Sterno-mastoid. It
arises from the anterior tubercles of
the transverse processes of the third,
fourth, fifth, and sixth cervical verte-
bras, and, descending almost vertically,
is inserted by a narrow, flat tendon
into the Scalene tubercle on the inner
border and upper surface of the first
rib. The lower part of this muscle sep-
arates the subclavian artery and vein,
the latter being in front, and the former,
with the brachial plexus, behind.
Relations. — In front, with the clav-
icle, the Subclavius, Sterno-mastoid,
and Omo-hyoid muscles, the Trans-
versalis colli, the suprascapular and
ascending cervical arteries, the subcla-
vian vein, and the phrenic nerve; by
its posterior surface, with the Scalenus
medius, pleura, subclavian artery, and
brachial plexus of nerves. It is sep-
arated from the Longus colli, on the
inner side, by the vertebral artery.
On the anterior tubercles of the trans-
verse processes of the cervical vertebrae,
between the attachments of the Scale-
nus anticus and Longus colli, lies the
FIG. 279.— Scaleni muscles. (Poirier and Charpy.) ascending Cervical branch of the infe'
rior thyroid artery.
The Scalenus Medius, the largest and longest of the three Scaleni, arises from
the posterior tubercles of the transverse processes of the lower six cervical vertebrae,
THE LATERAL VERTEBRAL REGION 41 1
and, descending along the side of the vertebral column, is inserted by a broad
attachment into the upper surface of the first rib, behind the groove for the sub-
clavian artery, as far back as the tubercle. It is separated from the Scalenus
anticus by the subclavian artery below and the cervical nerves above. The pos-
terior thoracic, or nerve of Bell, is formed in the substance of the Scalenus medius
and emerges from it. The nerve to the Rhomboids also pierces it.
Relations. — By its anterior surface, with the Sterno-mastoid ; it is crossed by
the clavicle, the Omo-hyoid muscle, subclavian artery, and cervical nerves. To
its outer side is the Levator anguli scapulae and the Scalenus posticus muscle.
The Scalenus Posticus (m. scalenus posterior), the smallest of the three Scaleni,
arises, by two or three separate tendons, from the posterior tubercles of the trans-
verse processes of the lower two or three cervical vertebras, and, diminishing as it
descends, is inserted by a thin tendon into the outer surface of the second rib,
behind the attachment of the Serratus magnus. This is the most deeply placed of
the three Scaleni, and is occasionally blended with the Scalenus medius.
Nerves. — The Rectus capitis anticus major and minor and the Rectus lateralis
are supplied by the first cervical nerve, and from the loop formed between it and
the second; the Longus colli and Scaleni, by branches from the anterior divisions
of the lower cervical nerves (fifth, sixth, seventh, and eighth) before they form the
brachial plexus. The Scalenus medius also receives a filament from the deep
external branches of the cervical plexus.
Actions. — The Rectus anticus major and minor are the direct antagonists of the
muscles at the back of the neck, serving to restore the head to its natural position
after it has been drawn backward. These muscles also serve to flex the head, and,
from their obliquity, rotate it, so as to turn the face to one or the other side. The
Longus colli flexes and slightly rotates the cervical portion of the spine. The
Scaleni muscles, when they take their fixed point from above, elevate the first and
second ribs, and are, therefore, inspiratory muscles. When they take their fixed
point from below, they bend the spinal column to one or the other side. If the
muscles of both sides act, lateral movement is prevented, but the spine is slightly
flexed. The Rectus lateralis, acting on one side, bends the head laterally.
Surface Form. — The muscles in the neck, with the exception of the Platysma myoides, are
invested by the deep cervical fascia, which softens down their form, and is of considerable
importance in connection with deep cervical abscesses and tumors, modifying the direction of
the growth of tumors and of the enlargement of abscesses, and causing them to extend
laterally instead of toward the surface. The Platysma myoides does not influence surface
form except when in action, when it produces wrinkling of the skin of the neck, which is
thrown into oblique ridges parallel with the fasciculi of the muscle. Sometimes this con-
traction takes place suddenly and repeatedly as a sort of spasmodic twitching, the result of
a nervous habit. The Slerno-deido-mastoid is the most important muscle of the neck as
regards its surface form. If the muscle is put into action by drawing the chin downward and
to the opposite shoulder, its surface form will be plainly outlined. The sternal origin will
stand out as a sharply-defined ridge, while the clavicular origin will present a flatter and not so
prominent an outline. The fleshy middle portion will appear as an oblique roll or elevation,
with a thick rounded anterior border gradually becoming less marked above. On the opposite
side — i. e., on the side to which the head is turned — the outline is lost, its place being occupied
by an oblique groove in the integument. When the muscle is at rest its anterior border is still
visible, forming an oblique rounded ridge, terminating below in the sharp outline of the sternal
head. The posterior border of the muscle does not show above the clavicular head. The
anterior border is defined by drawing a line from the tip of the mastoid process to the sterno-
clavicular joint. It is an important surface-marking in the operation of ligature of the common
carotid artery and in some other operations. Between the sternal and clavicular heads is a slight
depression, most marked when the muscle is in action. This is bounded below by the prominent
sternal extremity of the clavicle. Between the sternal origins of the two muscles is a V-shaped
space, the suprasternal notch, more pronounced below, and becoming toned down above, where
the Sterno-hyoid and Sterno-thyroid muscles, lying upon the trachea, become more prominent.
Above the hyoid bone, in the middle line, the anterior belly of the Digastric to a certain extent
influences surface form. It corresponds to a line drawn from the symphysis of the lower jaw to
412
THE MUSCLES AND FASCIA
the side of the body of the hyoid bone, and renders this part of the hyo-mental region convex.
In the posterior triangle of the neck, the posterior belly of the Omo-hyoid, when in action, forms
a conspicuous object, especially in thin necks, presenting a cord-like form running across this
region, almost parallel with, and a little above, the clavicle.
MUSCLES AND FASCLffi OF THE TRUNK.
The muscles of the Trunk may be arranged in four groups, corresponding
with the region in which they are situated.
I. The Back.
II. The Thorax.
III. The Abdomen.
IV. The Perinseum.
I. MUSCLES OF THE BACK.
The muscles of the Back are very numerous, and may be subdivided into five
layers :
FIRST LAYER.
Trapezius.
Latissimus dorsi.
SECOND LAYER.
Levator anguli scapulae.
Rhomboideus minor.
Rhomboideus major.
THIRD LAYER.
Serratus posticus superior.
Serratus posticus inferior.
Splenius capitis.
Splenius colli.
FOURTH LAYER.
Sacral and Lumbar Regions.
Erector spinse.
Dorsal Region.
Ilio-costalis.
Musculus accessorius ad ilio-costalem.
Longissimus dorsi.
Spinalis dorsi.
Cervical Region.
Cervicalis ascendens.
Transversalis cervicis.
Trachelo-mastoid.
Complexus.
Biventer cervicis.
Spinalis colli.
FIFTH LAYER.
Semispinalis dorsi.
Semispinalis colli.
Multifidus spinse.
Rotatores spinse.
Supraspinales.
Interspinales.
Extensor coccygis.
Intertransversalis.
Rectus capitis posticus major.
Rectus capitis posticus minor.
Obliquus capitis inferior.
Obliquus capitis superior.
The First Layer (Fig. 281).
Trapezius. Latissimus dorsi.
Dissection (Fig. 280).— Place the body in a prone position, with the arms extended over
the sides of the table, and the chest and abdomen supported by several blocks, so as to render
the muscles tense. Then make an incision along the middle line of the back from the occipital
protuberance to the coccyx. Make a transverse incision from the upper end of this to the mas-
toid process, and a third incision from its lower end, along the crest of the ilium to about its
middle. This large intervening space should, for convenience of dissection, be subdivided by
a fourth incision, extending obliquely from the spinous process of the last thoracic vertebra,
upward and outward, to the acromion process. This incision corresponds with the lower border
of the Trapezius muscle. The flaps of integument are then to be removed in the direction shown
in the figure.
OF THE BACK
413
Superficial Fascia. — The superficial fascia is exposed upon removing the skin
from the back. It forms a layer of considerable thickness and strength, in which
a quantity of granular pinkish fat is contained. It is continuous with the super-
ficial fascia in other parts of the body.
Deep Fascia. — The deep fascia is a dense fibrous layer attached to the
occipital bone, the spines of the vertebrae, the crest of the ilium, and the spine
of the scapula. It covers over the superficial
muscles, forming sheaths for them, and in the
neck forms the posterior part of the deep cer-
vical fascia; in the thorax it is continuous with
the deep fascia of the axilla and chest, and in
the abdomen with that covering the abdominal
muscles. In the back of the thoracic region
the deep fascia is called the vertebral aponeurosis
or the aponeurosis of the latissimus dorsi muscle.
It covers the erector spinse muscles, and is the
posterior layer of the lumbar fascia.
The Trapezius is a broad, flat, triangular
muscle, placed immediately beneath the skin
and fascia, and covering the upper and back
part of the neck and shoulders. It arises from
the external occipital protuberance and the
inner third of the superior curved line of the
occipital bone; from the ligamentum nuchse, the
spinous process of the seventh cervical, and the
spinous processes of all the thoracic vertebrae;
and from the corresponding portion of the
supraspinous ligament. From this origin the
superior fibres proceed downward and outward,
the inferior ones upward and outward, and
the middle fibres horizontally, and are in-
serted, the superior ones into the outer third of
the posterior border of the clavicle ; the middle
fibres into the inner margin of the acromion
process, and into the superior lip of the posterior border or crest of the spine
of the scapula; the inferior fibres converge near the scapula, and terminate in a
triangular aponeurosis, which glides over a smooth surface at the inner extremity
of the spine, to be inserted into a tubercle at the outer part of this smooth surface.
The Trapezius is fleshy in the greater part of its extent, but tendinous at its origin
and insertion. At its occipital origin it is connected to the bone by a thin fibrous
lamina, firmly adherent to the skin, and wanting the lustrous, shining appearance
of aponeuroses. At its origin from the spines of the vertebrae it is connected to
the bones by means of a broad semi-elliptical aponeurosis, which occupies the
space between the sixth cervical and the third thoracic vertebrae, and forms, with
the aponeurosis of the opposite muscle, a tendinous ellipse. The rest of the muscle
arises by numerous short tendinous fibres. If the Trapezius is dissected on both
sides, the two muscles resemble a trapezium or diamond-shaped quadrangle;
two angles corresponding to the shoulders; a third to the occipital protuberance;
and the fourth to the spinous process of the last thoracic vertebra. The
clavicular insertion of this muscle varies as to the extent of its attachment; it
sometimes advances as far as the middle of the clavicle, and may even become
blended with the posterior edge of the Sterno-mastoid or overlap it. This should
be borne in mind in the operation for tying the third part of the subclavian
artery.
FIG. 280. — Dissection of the muscles of
the back.
414
THE MUSCLES AND FASCIA
FIG. 281.— Muscles of the back. On the left side is exposed the first layer; on the right side, the second layet
and part of the third.
OF THE BACK 415
Relations. — By its superficial surface, with the integument; by its deep sur-
jace, in the neck, with the Complexus, Splenius, Levator anguli scapula?, and
Rhomboideus minor; in the back, with the Rhomboideus major, Supraspinatus,
Infraspinatus, and Vertebral aponeurosis (which separates it from the prolonga-
tions of the Erector spinae), and the Latissimus dorsi. The accessory nerve and
the superficial cervical artery and branches from the third and fourth cervical
nerves pass beneath the anterior border of this muscle. The anterior margin of its
cervical portion forms the posterior boundary of the posterior triangle of the neck,
the other boundaries being the Sterno-mastoid in front and the clavicle below.
The Ligamentum nuchae (Fig. 281) is a fibrous membrane, which, in the neck,
represents the supraspinous and interspinous ligaments of the lower vertebrae.
It extends from the external occipital protuberance to the spinbus process of the
seventh cervical vertebra. From its anterior border a fibrous lamina (fascia
nuchae) is given off, which is attached to the external occipital crest, the posterior
tubercle of the atlas, and the spinous process of each of the cervical vertebrae, so
as to form a septum between the muscles on each side of the neck. In man it is
merely the rudiment of an important elastic ligament, which, in some of .the lower
animals, serves to sustain the weight of the head.
The Latissimus Dorsi is a broad flat muscle, which covers the lumbar and the
lower half of the thoracic regions, and is gradually contracted into a narrow fascic-
ulus at its insertion into the humerus. It arises by tendinous fibres from the
spinous processes of the six inferior thoracic vertebras and from the posterior layer
of the lumbar fascia (see page 418), by which it is attached to the spines of the
lumbar and sacral vertebme and to the supraspinous ligament. It also arises
from the external lip of the crest of the ilium, behind the origin of the External
oblique, and by fleshy digitations from the three or four lower ribs, which are
interposed between similar processes of the External oblique muscle (Fig. 288,
page 436). From this extensive origin the fibres pass in different directions, the
upper ones horizontally, the middle obliquely upward, and the lower vertically
upward, so as to converge and form a thick fasciculus, which crosses the inferior
angle of the scapula, and occasionally receives a few fibres of origin from it. The
muscle then curves around the lower border of the Teres major, and is twisted
upon itself so that the superior fibres become at first posterior and then inferior,
and the vertical fibres at first anterior and then superior. It then terminates in a
short quadrilateral tendon, about three inches in length, which, passing in front of
the tendon of the Teres major, is inserted into the bottom of the bicipital groove
of the humerus, its insertion extending higher on the humerus than that of the
tendon of the Pectoralis major. The lower border of the tendon of this muscle is
united with that of the Teres major, the surfaces of the two being separated by a
bursa; another bursa is sometimes interposed between the muscle and the inferior
angle of the scapula. This muscle at its insertion gives off an expansion to the
deep fascia of the arm.
A muscular slip, the axillary arch, varying from 3 to 4 inches in length, and from J to f of an
inch in breadth, occasionally arises from the upper edge of the Latissimus dorsi about the mid-
dle of the posterior fold of the axilla, and crosses the axilla in front of the axillary vessels and
nerves, to join the under surface of the tendon of the Pectoralis major, the Coraco-brachialis,
or the fascia over the Biceps. The position of this abnormal slip is a point of interest in its
relation to the axillary artery, as it crosses the vessel just above the spot usually selected for the
application of a ligature, and may mislead the surgeon during the operation. It may be easily
recognized by the transverse direction of its fibres. Dr. Struther found it, in 8 out of 105 sub-
jects, occurring seven times on both sides. In most subjects there is a. fibrous axillary arch,
in only a few is the arch muscular.
There is usually a fibrous slip which passes from the lower border of the tendon of the Latis-
simus dorsi, near its insertion, to the long head of the Triceps. This is occasionally muscular,
and is the representative of the Dorso-epitrochlearis muscle of apes.
416 THE MUSCLES AND FASCIA
Relations. — Its superficial surface is subcutaneous, excepting at its upper part,
where it is covered by the Trapezius, and at its insertion, where its tendon is
crossed by the axillary vessels and the brachial plexus of nerves. By its deep
surface it is in relation with the lumbar fascia, the Serratus posticus inferior,
the lower External intercostal muscles and ribs, inferior angle of the scapula,
Rhomboideus major, Infraspinatus, and Teres major. Its outer margin is sepa-
rated below from the External oblique by a small triangular interval, the triangle
of Petit (trigonum lumbale [Petiti]) ; and another triangular interval exists between
its upper border and the margin of the Trapezius, in which the Rhomboideus
major muscle is exposed.
Nerves. — The Trapezius is supplied by the accessory, and by branches from
the anterior divisions of the third and fourth cervical nerves: the Latissimus
dorsi, by the middle or long subscapular nerve.
The Second Layer (Fig. 281).
Levator anguli scapulae. Rhomboideus minor.
Rhomboideus major.
Dissection. — The Trapezius must be removed, in order to expose the next layer; to effect
this, detach the muscle from its attachment to the clavicle and spine of the scapula, and turn
it back toward the spine.
The Levator Anguli Scapulae (m. levator scapulae) is situated at the back part
and side of the neck. It arises by tendinous slips from the transverse process of
the atlas, and from the posterior tubercles of the transverse processes of the second,
third, and fourth cervical vertebra?; these, becoming fleshy, are united so as to
form a flat muscle, which, passing downward and backward, is inserted into the
posterior border of the scapula, between the superior angle and the triangular
smooth surface at the root of the spine.
Relations. — By its superficial surface, with the integument, Trapezius, and
Sterno-mastoid ; by its deep surface, with the Splenius colli, Transversalis cervicis,
Cervicalis ascendens, and Serratus posticus superior muscles, and with the pos-
terior scapular artery and the nerve to the Rhomboids.
The Rhomboideus Minor arises from the ligamentum nuchae and spinous
processes of the seventh cervical and first thoracic vertebrae. Passing downward
and outward, it is inserted into the margin of the triangular smooth surface at the
root of the spine of the scapula. This small muscle is usually separated from the
Rhomboideus major by a slight cellular interval.
Relations. — By its superficial (posterior) surface, with the Trapezius; by its deep
(anterior) surface, with the same structures as the Rhomboideus major.
The Rhomboideus Major is situated immediately below the preceding, the
adjacent margins of the two being occasionally united. It arises by tendinous
fibres from the spinous processes of the four or five upper thoracic vertebrae and
the supraspinous ligament, and is inserted into a narrow tendinous arch attached
above to the lower part of the triangular surface at the root of the spine; below,
to the inferior angle, the arch being connected to the border of the scapula by a
thin membrane. When the arch extends, as it occasionally does, but a short
distance, the muscular fibres are inserted into the scapula itself.
Relations. — By its superficial (posterior) surface, with the Trapezius and Latis-
simus dorsi; by its deep (anterior) surface, with the Serratus posticus superior,
posterior scapular artery, the vertebral aponeurosis which separates it from the
prolongations from the Erector spinae, the Intercostal muscles, and ribs.
Nerves. — The Rhomboid muscles are supplied by branches from the anterior
division of the fifth cervical nerve; the Levator anguli scapulae, by the anterior
OF THE BACK 417
divisions of the third and fourth cervical nerves, and frequently by a branch from
the nerve to the Rhomboids.
Actions. — The movements effected by the preceding muscles are numerous, as
may be conceived from their extensive attachment. The whole of the Trapezius
when in action retracts the scapula and braces back the shoulder; if the head is
fixed, the upper part of the Trapezius will elevate the point of the shoulder, as in
supporting weights; when the lower fibres are brought into action, they assist
in depressing the bone. The middle and lower fibres of the muscle rotate the
scapula, causing elevation of the acromion process. If the shoulders are fixed, both
Trapezii, acting together, will draw the head directly backward; or if only one
acts the head is drawn to the corresponding side. The Latissimus dorsi, when it
acts upon the humerus, depresses it, draws it backward, adducts, and at the same
time rotates it inward. It is the muscle which is principally employed in giving a
downward blow, as in felling a tree or in sabre practice. If the arm is fixed, the
muscle may act in various ways upon the trunk; thus, it may raise the lower ribs
and assist in forcible inspiration; or, if both arms are fixed, the two muscles may
assist the Abdominal and great Pectoral muscles in suspending and drawing the
whole trunk forward, as in climbing or walking on crutches. The Levator anguli
scapulae raises the superior angle of the scapula, and by so doing depresses the
point of the shoulder. It assists the Trapezius in bearing weights and in shrugging
the shoulders. If the shoulder be fixed, the Levator anguli scapulae inclines the
neck to the corresponding side and rotates it in the same direction. The Rhom-
boid muscles carry the inferior angle backward and upward, thus producing a
slight rotation of the scapula upon the side of the chest, the Rhomboideus major
acting especially on the lower angle of the scapula through the tendinous arch by
which it is inserted. The Rhomboid muscles, acting together with the middle and
inferior fibres of the Trapezius, will draw the scapula directly backward toward
the spine.
The Third Layer.
Serratus posticus superior. Serratus posticus inferior.
f Splenius capitis.
Splemus slenius collL
Dissection. — To bring into view the third layer of muscles, remove the whole of the second,
together with the Latissimus dorsi, by cutting through the Levator anguli scapulae and Rhom-
boid muscles near their origin, and reflecting them downward, and by dividing the Latissimus
dorsi in the middle by a vertical incision carried from its upper to its lower part, and reflecting
the two halves of the muscle.
The Serratus Posticus Superior (m. serratus posterior superior) is a thin, flat,
quadrilateral muscle situated at the upper and back part of the thorax. It arises
by a thin and broad aponeurosis from the ligamentum nuchae, and from the
spinous processes of the last cervical and two or three upper thoracic vertebrae and
from the supraspinous ligament. Inclining downward and outward, it becomes
muscular, and is inserted, by four fleshy digitations, into the upper borders of the
second, third, fourth, and fifth ribs, a little beyond their angles.
Relations. — By its superficial surface, with the Trapezius, Rhomboidei, and
Levator anguli scapulae; by its deep surface, with the Splenius and the vertebral
aponeurosis, which separates it from the prolongations of the Erector spinae, and
with the Intercostal muscles and ribs.
The Serratus Posticus Inferior (m. serratus posterior inferior] (Fig. 281) is
situated at the junction of the thoracic and lumbar regions; it is of an irregularly
quadrilateral form, broader than the preceding, and separated from it by a consid-
erable interval. It arises by a thin aponeurosis from the spinous processes of the
last two thoracic and two or three upper lumbar vertebrae, and from the supra-
27
418 THE MUSCLES AND FASCIAE
spinous ligaments. Passing obliquely upward and outward, it becomes fleshy,
and divides into four flat digitations, which are inserted into the lower borders of
the four lower ribs, a little beyond their angles. The thin aponeurosis of origin
is intimately blended with the lumbar fascia.
Relations. — By its superficial surface, with the Latissimus dorsi. By its deep
surface, with the Erector spinse, ribs, and Intercostal muscles. Its upper margin
is continuous with the vertebral aponeurosis.
The vertebral aponeurosis is a thin, fibrous lamina, extending along the whole
length of the back part of the thoracic region, serving to bind down the long
Extensor muscles of the back which support the spine and head, and separate them
from those muscles which connect the spine to the upper extremity. It consists of
longitudinal and transverse fibres blended together, forming a thin lamella, which
is attached in the median line to the spinous processes of the thoracic vertebrae;
externally, to the angles "of the ribs ; and below, to the upper border of the Serratus
posticus inferior and a portion of the lumbar fascia, which gives origin to the Latis-
simus dorsi; above, it passes beneath the Serratus posticus superior and the
Splenius, and blends with the deep fascia of the neck.
The lumbar fascia or aponeurosis (Figs. 281 and 294), which may be regarded
as the posterior aponeurosis of the Transversalis abdominis muscle, consists
of three laminae, which are attached as follows: the posterior layer, to the
spines of the lumbar and sacral vertebras and their supraspinous ligaments; the
middle layer, to the tips of the transverse processes of the lumbar vertebrae and
their intertrans verse ligaments; the anterior layer, to the roots of the lumbar
transverse processes. The posterior layer is continued above as the vertebral
aponeurosis, while inferiorly it is fixed to the outer lip of the iliac crest. With this
layer are blended the aponeurotic origin of the Serratus posticus inferior and part
of that of the Latissimus dorsi. The middle layer is attached above to the last
rib, and below to the iliac crest; the anterior layer is fixed below to the ilio-lumbar
ligament and iliac crest; while above it is thickened to form the external arcuate
ligament of the Diaphragm, and stretches from the tip of the last rib to the trans-
verse process of the first or second lumbar vertebra. These three layers, together
with the vertebral column, enclose two spaces, the posterior of which is occupied
by the Erector spinas muscle, and the anterior by the Quadratus lumborum.
Now detach the Serratus posticus superior from its origin, and turn it outward, when the
Splenius muscle will be brought into view.
The Splenius (Fig. 281) is situated at the back of the neck and upper part
of the thoracic region. At its origin it is a single muscle, which soon after its
origin becomes broad, and divides into two portions, which have separate inser-
tions. It arises, by tendinous fibres, from the lower half of the ligamentum
nuchae, from the spinous processes of the last cervical and of the six upper tho-
racic vertebrae, and from the supraspinous ligament. From this origin the fleshy
fibres proceed obliquely upward and outward, forming a broad flat muscle, which
divides as it ascends into two portions, the Splenius capitis and Splenius colli.
The Splenius capitis (TO. splenius capitis) is inserted into the mastoid process of
the temporal bone, and into the rough surface on the occipital bone just beneath
the superior curved line.
The Splenius colli (TO. splenius cervicis) is inserted, by tendinous fasciculi, into the
posterior tubercles of the transverse processes of the two or three upper cervical
vertebrae.
The Splenius is separated from its fellow of the opposite side by a triangular
interval, in which is seen the Complexus.
Relations. — By its superficial surface, with the Trapezius, from which it is sepa-
rated below by the Rhomboidei and the Serratus posticus superior. It is covered
OF THE BACK 419
at its insertion by the Sterno-mastoid, and at the lower and back part of the neck
by the Levator anguli scapulae; by its deep surface, with the Spinalis dorsi, Longis-
simus dorsi, Semispinalis colli, Complexus, Trachelo-mastoid, and Transversalis
cervicis.
Nerves. — The Splenius is supplied from the external branches of the posterior
divisions of the cervical nerves; the Serratus posticus superior is supplied by the
external branches of the posterior divisions of the upper thoracic nerves; the
Serratus posticus inferior by the external branches of the posterior divisions of
the lower thoracic nerves.
Actions. — The Serrati are respiratory muscles. The Serratus posticus supe-
rior elevates the ribs; it is therefore an inspiratory muscle; while the Serratus
inferior draws the lower ribs downward and backward, and thus elongates the
thorax. It also fixes the lower ribs, thus aiding the downward action of the
diaphragm and resisting the tendency which it has to draw the lower ribs upward
and forward. It must therefore be regarded as a muscle of inspiration. This
muscle is also probably a tensor of the vertebral aponeurosis. The Splenii muscles
of the two sides, acting together, draw the head directly backward, assisting the
Trapezius and Complexus; acting separately, they draw the head to one or the
other side, and slightly rotate it, turning the face to the same side. They also
assist in supporting the head in the erect position.
The Fourth Layer (Fig. 282).
I. Erector spinse.
a. Outer Column. b. Middle Column.
Ilio-costalis. Longissirnus dorsi.
Musculus accessorius. Transversalis cervicis.
Cervicalis ascendens. Trachelo-mastoid.
c. Inner Column.
Spinalis dorsi. Spinalis colli.
II. Complexus.
Dissection. — To expose the muscles of the fourth layer, remove entirely the Serrati and the
vertebral and lumbar fascise. Then detach the Splenius by separating its attachment to the
spinous processes and reflecting it outward.
The Erector Spinae (m. sacrospinalis] and its prolongations in the thoracic
and cervical regions fill up the vertebral groove on each side of the spine. It
is covered in the lumbar region by the lumbar fascia; in the thoracic region, by
the Serrati muscles and the vertebral aponeurosis; and in the cervical region, by
a layer of cervical fascia continued beneath the Trapezius and the Splenius. This
large muscular and tendinous mass varies in size and structure at different parts
of the spine. In the sacral region the Erector spinae is narrow and pointed, and
its origin chiefly tendinous in structure. In the lumbar region the muscle becomes
enlarged, and forms a large, fleshy mass. In the thoracic region it subdivides into
two parts, which gradually diminish in size as they ascend to be inserted into the
vertebrae and ribs.
The Erector spinae arises from the anterior surface of a very broad and thick
tendon, which is attached, internally, to the spines of the sacrum, to the spinous
processes of the lumbar and the eleventh and twelfth thoracic vertebrae, and the
supraspinous ligament; externally, to the back part of the inner lip of the crest of
the ilium, and to the series of eminences on the posterior part of the sacrum, which
represents the transverse processes, where it blends with the great sacro-sciatic and
posterior sacro-iliac ligaments. Some of its fibres are continuous with the fibres
420
THE MUSCLES AND FASCIA
Occipital bone.
MULTIFIDUS SPIN>E.
First dorsal vertebra.
First lumbar vertebra.
First sacral vertebra.
FIG. 282. — Muscles of the back. Deep layers.
OF THE BACK 421
of origin of the Gluteus maximus. The muscular fibres form a single large fleshy
mass, bounded in front by the transverse processes of the lumbar vertebrae and by
the middle lamella of the lumbar fascia. Opposite the last rib it divides into two
parts, the Ilio-costalis and the Longissimus dorsi; the Spinalis dorsi is given off
from the latter in the upper thoracic region.
The Hio-costalis or Sacro-lumbalis (m. iliocostalis lumborum), the external por-
tion of the Erector spinae, is inserted, generally, by six or seven flattened tendons into
the inferior borders of the angles of the six or seven lower ribs. The number of the
tendons of this muscle is, however, very variable, and therefore the number of ribs
into which it is inserted vary. Frequently it is found to possess nine or ten
tendons, and sometimes as many tendons as there are ribs, and is then inserted
into the angles of all the ribs. If this muscle is reflected outward, it will be
seen to be reinforced by a series of muscular slips which arise from the angles
of the ribs; by means of these the Ilio-costalis is continued upward to the upper
ribs and cervical portion of the spine. The accessory portions form two additional
muscles, the Musculus accessorius and the Cervicalis ascendens.
The Musculus accessorius ad ilio-costalem (m. iliocostalis dorsi) arises, by separate
flattened tendons, from the upper borders of the angles of the six lower ribs: these
become muscular, and are finally inserted, by separate tendons, into the upper
borders of the angles of the six upper ribs and into the back of the transverse
processes of the seventh cervical vertebra.
The Cervicalis ascendens1 (m. iliocostalis cervicis) is the continuation of the Acces-
sorius upward into the neck; it is situated on the inner *ide of the tendons of the
Accessorius, arising from the angles of the four or five upper ribs, and is inserted
by a series of slender tendons into the posterior tubercles of the transverse processes
of the fourth, fifth, and sixth cervical vertebra?.
The Longissimus dorsi is the middle and largest portion of the Erector spinae.
In the lumbar region, where it is as yet blended with the Ilio-costalis, some of the
fibres are attached to the whole length of the posterior surface of the transverse
processes and the accessory processes of the lumbar vertebrae, and to the middle
layer of the lumbar fascia. In the thoracic region the Longissimus dorsi is inserted,
by long, thin tendons, into the tips of the transverse processes of all the thoracic
vertebras, and into from seven to eleven of the lower ribs between their tubercles
and angles. This muscle is continued upward to the cranium and cervical portion
of the spine by means of two additional muscles, the Transversalis cervicis and
Trachelo-mastoid.
The Transversalis cervicis or Transversalis colli (m. longissimus cervicis}, placed
on the inner side of the Longissimus dorsi, arises by long, thin tendons from the
summits of the transverse processes of the six upper thoracic vertebrae, and is
inserted by similar tendons into the posterior tubercles of the transverse processes
of the cervical vertebras, from the second to the sixth inclusive.
The Trachelo-mastoid (m. longissimus capitis) lies on the inner side of the preced-
ing, between it and the Complexus muscle. It arises, by tendons, from the trans-
verse processes of the five or six upper thoracic vertebrae, and the articular processes
of the three or four lower cervical. The fibres form a small muscle, which ascends
to be inserted into the posterior margin of the mastoid process, beneath the Splenius
and Sterno-mastoid muscles. This small muscle is almost always crossed by a
tendinous intersection near its insertion into the mastoid process.2
The Spinalis dorsi connects the spinous processes of the upper lumbar and the
thoracic vertebrae together by a series of muscular and tendinous slips which are
This muscle is sometimes called "Cervicalis descendens." The student should remember that these long
muscles take their fixed point from above or from below, according to circumstances. — ED. of 15th English
edition.
2 These two muscles (Transversalis cervicis and Trachelo-mastoid) are sometimes described as one, having a
common origin, but dividing above at their insertion. The Trachelo-mastoid is then termed the Transversalis
capiti*. — ED. of 15th English edition.
422 THE MUSCLES AND FASCIA
intimately blended with the Longissimus dorsi. It is situated at the inner side
of the Longissimus dorsi, arising, by three or four tendons, from the spinous
processes of the first two lumbar and the last two thoracic vertebrae: these, uniting,
form a small muscle, which is inserted, by separate tendons, into spinous processes
of the thoracic vertebrae, the number varying from four to eight. It is intimately
united with the Semispinalis dorsi, which lies beneath it.
The Spinalis colli (TO. spinalis cervicis) is a small muscle, connecting together the
spinous processes of the cervical vertebrae, and analogous to the Spinalis dorsi in
the thoracic region. It varies considerably in its size and in its extent of attachment
to the. vertebras, not only in different bodies, but on the two sides of the same body.
It usually arises by fleshy or tendinous slips, varying from two to four in number,
from the spinous processes of the fifth, sixth, and seventh cervical vertebras, and
occasionally from the first and second thoracic, and is inserted into the spinous
process of the axis, and occasionally into the spinous processes of the two vertebrae
below it. This muscle was found absent in five cases out of twenty-four.
Relations. — The Erector spinae and its prolongations are bound down to the
vertebrae and ribs in the lumbar and thoracic regions by the lumbar fascia and
the vertebral aponeurosis. The inner part of these muscles covers the muscles
of the fifth layer. In the neck they are in relation, by their superficial surface, with
the Trapezius and Splenius; by their deep surface, with the Semispinalis dorsi et
colli and the Recti and Obliqui.
The Complexus (m. Semispinalis capitis} is a broad thick muscle, situated at the
upper and back part of tFie neck, beneath the Splenius, and internal to the Trans-
versalis cervicis and Trachelo-mastoid. It arises, by a series of tendons, from
the tips of the transverse processes of the upper six or seven thoracic and the last
cervical vertebrae, and from the articular processes of the three cervical above
this. The tendons, uniting, form a broad muscle, which passes obliquely upward
and inward, and is inserted into the innermost depression between the two curved
lines of the occipital bone. This muscle, about its middle, is traversed by a trans-
verse tendinous intersection. The biventor cervicis is a small fasciculus, situated
on the inner side of the preceding, and in the majority of cases blended with it;
it has received its name from having a tendon intervening between two fleshy
bellies. It is sometimes described as a part of the Complexus. It arises, by from
two to four tendinous slips, from the transverse processes of as many of the upper
thoracic vertebrae, and is inserted, on the inner side of the Complexus, into the supe-
rior curved line of the occipital bone.
Relations. — The Complexus is covered by the Splenius and the Trapezius. It
lies on the Rectus capitis posticus major and minor, the Obliquus capitis superior
and inferior, and on the Semispinalis colli, from which it is separated by the pro-
funda cervicis artery, the princeps cervicis artery, and branches of the posterior
primary divisions of the cervical nerves. The Biventer cervicis is separated from
its fellow of the opposite side by the ligamentum nuchae.
The Fifth Layer (Fig. 282).
Semispinalis dorsi. Extensor coccygis.
Semispinalis colli. Intertransversales.
Multifidus spinae. Rectus capitis posticus major.
Rotatores spinae. Rectus capitis posticus minor.
Supraspinales. Obliquus capitis inferior.
Interspinales. Obliquus capitis superior.
Dissection. — Remove the muscles of the preceding layer by dividing and turning aside the
Complexus; then detach the Spinalis and Longissimus dorsi from their attachments, divide the
Erector spinse at its connection below to the sacral and lumbar spines and turn it outward. The
muscles filling up the interval between the spinous and transverse processes are then exposed.
OF THE BACK 423
The Semispinalis Dorsi consists of thin, narrow, fleshy fasciculi interposed
between tendons of considerable length. It arises by a series of small tendons
from the transverse processes of the lower thoracic vertebra?, from the tenth or
eleventh to the fifth or sixth; and is inserted, by five or six tendons, into the
spinous processes of the upper four thoracic and lower two cervical vertebrae.
The Semispinalis Colli (m. semispinalis cervicis}, thicker than the preceding,
arises by a series of tendinous and fleshy fibres from the transverse processes of
the upper five or six thoracic vertebrae, and is inserted into the spinous processes of
four cervical vertebrae, from the axis to the fifth cervical. The fasciculus con-
nected with the axis is the largest, and chiefly muscular in structure.
Relations. — By their superficial surface, from below upward, with the Spinalis
dorsi, Longissimus dorsi, Splenius, Complexus, the profunda cervicis artery, the
princeps cervicis artery, and the internal branches of the posterior divisions of
the first, second, and third cervical nerves; by their deep surface, with the Mul-
tifidus spinae.
The Multifidus Spinae (m. multifidus) consists of a number of fleshy and ten-
dinous fasciculi which fill up the groove on either side of the spinous processes of the
vertebrae, from the sacrum to the axis. In the sacral region these fasciculi arise from
the back of the sacrum, as low as the fourth sacral foramen, and from the aponeu-
rosis of origin of the Erector spinae; from the inner surface of the posterior superior
spine of the ilium and posterior sacro-iliac ligaments; in the lumbar regions, from
the articular processes; in the thoracic region, from the transverse processes; and
in the cervical region, from the articular processes of the three or four lower verte-
brae. Each fasciculus, passing obliquely upward and inward, is inserted into the
whole length of the spinous process of one of the vertebrae above. These fasciculi
vary in length : the most superficial, the longest, pass from one vertebra to the third
or fourth above; those next in order pass from one vertebra to the second or third
above ; whilst the deepest connect two contiguous vertebrae.
Relations. — By its superficial surface, with the Longissimus dorsi, Spinalis dorsi,
Semispinalis dorsi, and Semispinalis colli; by its deep surface, with the laminae
and spinous processes of the vertebrae, and with the Rotatores spinae in the thoracic
region.
The Rotatpres Spinse (mm. rotatores] are found only in the thoracic region of the
spine, beneath the Multifidus spinae; they are eleven in number on each side. Each
muscle is small and somewhat quadrilateral in form; it arises from the upper and
back part of the transverse process, and is inserted into the lower border and outer
surface of the lamina of the vertebra above, the fibres extending as far inward as
the root of the spinous process. The first is found between the first and second
thoracic; the last, between the eleventh and twelfth. Sometimes the number of these
muscles is diminished by the absence of one or more from the upper or lower end.
The Supraspinales consist of a series of fleshy bands which lie on the spinous
processes in the cervical region of the spine.
The Interspinales are short muscular fasciculi, placed in pairs between the
spinous processes of the contiguous vertebrae, one on each side of the interspinous
ligament. In the cervical region they are most distinct, and consist of six pairs,
the first being situated between the axis and third vertebra, and the last between
the last cervical and the first thoracic. They are small narrow bundles, attached,
above and below, to the apices of the spinous processes. In the thoracic region
they are found between the first and second vertebrae, and occasionally between
the second and third; and below, between the eleventh and twelfth. In the
lumbar region there are four pairs of these muscles in the intervals between the
five lumbar vertebrae. There is also occasionally one in the interspinous space
between the last thoracic and first lumbar, and between the fifth lumbar and the
sacrum.
424 THE MUSCLES AND FASCIA
The Extensor Coccygis is a slender muscular fasciculus, occasionally present,
which extends over the lower part of the posterior surface of the sacrum and
coccyx. It arises by tendinous fibres from the last bone of the sacrum or first
piece of the coccyx, and passes downward to be inserted into the lower part of
the coccyx. It is a rudiment of the Extensor muscle of the caudal vertebrae of
the lower animals.
The Intertransversales (mm. intertransversarii) are small muscles placed
between the transverse processes of the vertebrae. In the cervical region they are
most developed, consisting of rounded muscular and tendinous fasciculi, which are
placed in pairs, passing between the anterior and the posterior tubercles of the
transverse processes of two contiguous vertebrae, separated from one another by
the anterior division of the cervical nerve, which lies in the groove between them.
In this region there are seven pairs of these muscles, the first pair being between
the atlaS and axis, and the last pair between the seventh cervical and first thoracic
vertebrae. In the thoracic region they are least developed, consisting chiefly of
rounded tendinous cords in the intertransverse spaces of the upper thoracic verte-
brae; but between the transverse processes of the lower three thoracic vertebrae, and
between the transverse processes of the last thoracic and the first lumbar, they are
muscular in structure. In the lumbar region they are arranged in pairs, on either
side of the spine, one set occupying the entire interspace between the transverse
processes of the lumbar vertebrae, the intertransversales laterales (mm. intertrans-
versarii laterales} ; the other set, intertransversales mediales (mm. intertransversarii
mediales}, passing from the accessory process of one vertebra to the mammillary
process of the next.
The Rectus Capitis Posticus Major (m. rectus capitis posterior major} arises by
a pointed tendinous origin from the spinous process of the axis, and, becoming
broader as it ascends, is inserted into the inferior curved line of the occipital bone
and the surface of bone immediately below it. As the muscles of the two sides pass
upward and outward, they leave between them a triangular space, in which are
seen the Recti capitis postici minores muscles.
Relations. — By its superficial surface, with the Complexus, and, at its insertion,
with the Superior oblique; by its deep surface, with part of the Rectus capitis
posticus minor, the posterior arch of the atlas, the posterior occipito-atlantal liga-
ment, and part of the occipital bone.
The Rectus Capitis Posticus Minor (m. rectus capitis posterior minor], the small-
est of the four muscles in this region, is of a triangular shape; it arises by a narrow
pointed tendon from the tubercle on the posterior arch of the atlas, and, becom-
ing broader as it ascends, is inserted into the rough surface beneath the inferior
curved line, nearly as far as the foramen magnum, nearer to the middle line than
the preceding.
Relations.— By its superficial surface, with the Complexus and the Rectus capitis
posticus major; by its deep surface, with the posterior occipito-atlantal ligament.
The Obliquus Capitis Inferior, the larger of the two Oblique muscles, arises
from the apex of the spinous process of the axis, and passes outward and slightly
upward, to be inserted into the lower and back part of the transverse process of
the atlas.
Relations. — By its superficial surface, with the Complexus and with the pos-
terior division of the second cervical nerve, which crosses it; by its deep surface,
with the vertebral artery and posterior atlanto-axial ligament.
The Obliquus Capitis Superior, narrow below, wide and expanded above,
arises by tendinous fibres from the upper surface of the transverse process of the
atlas, joining with the insertion of the preceding, and, passing obliquely upward
and inward, is inserted into the occipital bone, between the two curved lines,
external to the Complexus.
OF THE BACK 425
Relations. — By its superficial surface, with the Complexus and Trachelo-mastoid
and occipital artery. By its deep surf ace, with the posterior occipito-atlantal ligament.
Between the two oblique muscles and the Rectus capitis posticus major a trian-
gular interval exists, the suboccipital triangle. This triangle is- bounded, above
and internally, by the Rectus capitis posticus major; above and externally, by the
Obliquus capitis superior; below and externally, by the Obliquus capitis inferior.
It is covered in by a layer of dense fibro-fatty tissue, situated beneath the Com-
plexus muscle. The floor is formed by the posterior occipito-atlantal ligament
and the posterior arch of the atlas. It contains the vertebral artery, as it runs in
a deep groove on the upper surface of the posterior arch of the atlas, and the pos-
terior division of the suboccipital nerve.
Nerves.— The third, fourth, and fifth layers of the muscles of the back are
supplied by the posterior primary divisions of the spinal nerves.
Actions. — When both the Spinales dorsi contract, they extend the thoracic region
of the spine; when only one muscle contracts, it helps to bend the thoracic por-
tion of the spine to one side. The Erector spinse, comprising the Ilio-costalis and
the Ixmgissimus dorsi with their accessory muscles, serves, as its name implies,
to maintain the spine in the erect posture; it also serves to bend the trunk back-
ward when it is required to counterbalance the influence of any weight at the
front of the body, as, for instance, when a heavy weight is suspended from the
neck, or when there is any great abdominal distention, as in pregnancy or dropsy;
the peculiar gait under such circumstances depends upon the spine being drawn
backward by the counterbalancing action of the Erector spinse muscles. The
muscles which form the continuation of the Erector spinse upward steady the
head and neck, and fix them in the upright position. If the Ilio-costalis and
Longissimus dorsi of one side act, they serve to draw down the chest and spine to
the corresponding side. The Cervicales ascendens, taking their fixed points from
the cervical vertebrse, elevate those ribs to which they are attached; taking their
fixed points from the ribs, both muscles help to extend the neck; while one muscle
bends the neck to its own side. The Transversalis cervicis, when both muscles act,
taking their fixed point from below, bend the neck backward. The Trachelo-
mastoid, when both muscles act, taking their fixed point from below, bend the head
backward; while, if only one muscle acts, the face is turned to the side on which
the muscle is acting, and then the head is bent to the shoulder. The two Recti
muscles draw the head backward. The Rectus capitis posticus major, owing to
its obliquity, rotates the cranium, with the atlas, round the odontoid process,
turning the face to the same side. The Multifidus spinse acts successively upon the
different parts of the spine; thus, the sacrum furnishes a fixed point from which
the fasciculi of this muscle act upon the lumbar region; these then become the
fixed points for the fasciculi moving the thoracic region, and so on throughout the
entire length of the spine; it is by the successive contraction and relaxation of
the separate fasciculi of this and other muscles that the spine preserves the erect
posture without the fatigue that would necessarily have been produced had this
position been maintained by the action of a single muscle. The Multifidus spinae,
besides preserving the erect position of the spine, serves to rotate it, so that the
front of the trunk is turned to the side opposite to that from which the muscle
acts, this muscle being assisted in its action by the Obliquus externus abdominis.
The Complexi draw the head directly backward: if one muscle acts, it draws
the head to one side, and rotates it so that the face is turned to the opposite
side. The Superior oblique draws the head backward, and, from the obliquity
in the direction of its fibres, will slightly rotate the cranium, turning the face to
the opposite side. The Obliquus capitis inferior rotates the atlas, and with it the
cranium, round the odontoid process, turning the face to the same side. The
Semispinales, when the muscles of the two sides act together, help to extend the
426 THE MUSCLES AND FASCIA
spine; when the muscles of one side only act, they rotate the thoracic and cervical
parts of the spine, turning the body to the opposite side. The Supraspinales and
Interspinales by approximating the spinous processes help to extend the spine.
The Intertransversales approximate the transverse processes, and help to bend the
spine to one side. The Rotatores spinse assist the Multifidus spinse to rotate the
spine, so that the front of the trunk is turned to the side opposite to that from
which the muscle acts.
Surface Forms. — The surface forms produced by the muscles of the back are numerous and
difficult to analyze unless they are considered in systematic order. The most superficial layer,
consisting of large strata of muscular substance, influences to a certain extent the surface form,
and at the same time reveals the forms of the layers beneath. The Trapezius at the upper part
of the back, and in the neck, covers over and softens down the outline of the underlying muscles.
Its anterior border forms the posterior boundary of the posterior triangle of the neck. It forms
a slight undulating ridge which passes downward and forward from the occiput to the junction
of the middle and outer third of the clavicle. The tendinous ellipse formed by a part of the
origin of the two muscles at the back of the neck is always to be seen as an oval depression,
more marked when the muscle is in action. A slight dimple on the skin opposite the interval
between the spinous processes of the third and fourth thoracic vertebrae marks the triangular
aponeurosis by which the inferior fibres are inserted into the root of the spine of the scapula.
From this point the inferior border of the muscle may be traced as an undulating ridge to the
spinous process of the twelfth thoracic vertebra. In like manner the Latissimus dorsi softens
down and modulates the underlying structures at the lower part of the back and lower part of
the side of the chest. In this way it modulates the outline of the Erector spinse; of the Serratus
posticus inferior, which is sometimes to be discerned through it, and is sometimes entirely
obscured by it; of part of the Serratus magnus and Superior oblique, which it covers; and of
the convex oblique ridges formed by the ribs with the intervening intercostal spaces. The
anterior border of the muscle is the only part which gives a distinct surface form. This border
may be traced, when the muscle is in action, as a rounded edge, starting from the crest of the
ilium, and passing obliquely forward and upward to the posterior border of the axilla, where it
combines with the Teres major in forming a thick rounded fold, the posterior boundary of the
axillary space. The muscles in the second layer influence to a very considerable extent the sur-
face form of the back of the neck and upper part of the trunk. The Levator anguli scapulae
reveals itself as a prominent divergent line, running downward and outward, from the trans-
verse processes of the upper cervical vertebrae to the angle of the scapula, covered over and
toned down by the overlying Trapezius. The Rhomboidei produce, when in action, a vertical
eminence between the vertebral border of the scapula and the spinal furrow, varying in intensity
according to the condition of contraction or relaxation of the Trapezius muscle, by which they
are for the most part covered. The lowermost part of the Rhomboideus major is uncovered
by the Trapezius, and forms on the surface an oblique ridge running upward and inward from
the 'inferior angle of the scapula. Of the muscles of the third layer of the back, the Serratus
posticus superior does not in any way influence surface form. The Serratus posticus inferior,
when in strong action, may occasionally be revealed as an elevation beneath the Latissimus
dorsi. The Splenii by their divergence serve to broaden out the upper part of the back of the
neck and produce a local fulness in this situation, but do not otherwise influence surface form.
Beneath all these muscles those of the fourth layer — the Erector spinae and its continuations —
influence the surface form in a decided manner. In the loins, the Erector spinae, bound down
by the lumbar fascia, forms a rounded vertical eminence, which determines the depth of the
spinal furrow, and which below tapers to a point on the posterior surface of the sacrum and
becomes lost there. In the back it forms a flattened plane1 which gradually becomes lost. In
the neck the only part of this group of muscles which influences surface form is the Trachelo-
mastoid, which produces a short convergent line across the upper part of the posterior triangle
of the neck, appearing from under cover of the posterior border of the Sterno-mastoid and
being lost below beneath the Trapezius.
II. MUSCLES AND FASCIA OF THE THORAX.
The muscles belonging exclusively to this region are few in number. They are the
Intercostales externi. Triangularis sterni.
Intercostales interni. Levatores costarum.
Infracostales. Diaphragm.
Intercostal Fascia. — A thin but firm layer of fascia covers the outer surface of
the External intercostal and the inner surface of the Internal intercostal muscles;
OF THE THORAX 427
and a third layer, more delicate, is interposed between the two planes of muscular
fibres. These are the intercostal fasciae, external, middle, and internal; they are best
marked in those situations where the muscular fibres are deficient, as between the
External intercostal muscles and sternum, in front, and between the Internal
intercostals and spine, behind.
The Intercostal Muscles (Figs. 290 and 314) are two thin planes of muscular
and tendinous fibres, placed one over the other, filling up the intercostal spaces,
and being directed obliquely between the margins of the adjacent ribs. They
have received the name external and internal from the position they bear to one
another. The tendinous fibres are longer and more numerous than the muscular;
hence the walls of the intercostal spaces possess very considerable strength, to
which the crossing of the muscular fibres materially contributes.
The External Intercostals (mm. intercostales externi) are eleven in number on
each side. They extend from the tubercles of the ribs, behind, to the commence-
ment of the cartilages of the ribs, in front, where they terminate in a thin mem-
brane, the anterior intercostal membrane, which is continued forward to the sternum.
They arise from the lower border of the rib above, and are inserted into the upper
border of the rib below7. In the two lowest spaces they extend to the ends of the
cartilages, and in the upper two or three spaces they do not quite extend to the ends
of the ribs. Their fibres are directed obliquely downward and forward, in a
similar direction with those of the External oblique muscle of the abdomen.
They are thicker than the Internal intercostals.
Relations. — By their outer surface, with the muscles which immediately invest
the chest — viz., the Pectoralis major and minor, Serratus magnus, and Rhom-
boideus major, Serratus posticus superior and inferior, Scalenus posticus, Ilio-
costalis, Longissimus dorsi, Cervicalis ascendens, Transversalis cervicis, Leva-
tores costarum, Obliquus externus abdominis, and the Latissimus dorsi; by their
internal surface, with the middle intercostal fascia, which separates them from the
intercostal vessels and nerve and the Internal intercostal muscles, and, behind,
from the pleura.
The Internal Intercostals (mm. intercostales interni) are also eleven in number on
each side. They commence anteriorly at the sternum in the interspaces between
the cartilages of the true ribs, and from the anterior extremities of the cartilages
of the false ribs, and extend backward as far as the angles of the ribs, whence they
are continued to the vertebral column by a thin aponeurosis, the posterior inter-
costal membrane. They arise from the ridge on the inner surface of the rib above,
as well as from the corresponding costal cartilage, and are inserted into the upper
border of the rib below. Their fibres are directed obliquely downward and back-
ward, passing in the opposite direction to the fibres of the External intercostal
muscle.
Relations. — By their external surface, with the intercostal vessels and nerves
and the External intercostal muscles; near the sternum, with the anterior inter-
costal membrane and the Pectoralis major. By their internal surface, with the
pleura costalis, Triangularis sterni, and Diaphragm.
The Infracostales (mm. subcostales] consist of muscular and aponeurotic fas-
ciculi, which vary in number and length; they are placed on the inner surface of the
ribs, where the Internal intercostal muscles cease; they arise from the inner sur-
face of one rib, and are inserted into the inner surface of the first, second, or third
rib below. Their direction is most usually oblique, like the Internal intercostals.
They are most frequent between the lower ribs.
The Triangularis Sterni (m. transversus thoracis} (Fig. 283) is a thin plane of
muscular and tendinous fibres, situated upon the inner wall of the front of the chest.
It arises from the lower third of the posterior surface of the sternum, from the
posterior surface of the ensiform cartilage, and from the sternal ends of the costal
428
cartilages of the three or four lower true ribs. Its fibres diverge upward and out-
ward, to be inserted by digitations into the lower borders and inner surfaces of the
costal cartilages of the second, third, fourth, fifth, and sixth ribs. The lowest
fibres of this muscle are horizontal in their direction, and are continuous with
those of the Transversalis ; those which succeed are oblique, whilst the superior
fibres are almost vertical. This muscle varies much in its attachment, not only in
different bodies, but on opposite sides of the same body.
Relations. — In front, with the sternum, ensiform cartilage, costal cartilages,
Internal intercostal muscles, and internal mammary vessels; behind, with the
pleura, pericardium, and anterior mediastinum.
STERNO-MASTOID.
SUBCLAVIUS.
SUBCLAVIUS.
Internal mam-
mary artery.
,TRIANGULARIS
STERNI.
TRANSVERSALIS ABDOMINIS.
FIG. 283. — Posterior surface of sternum and costal cartilages, showing Triangularis sterni muscle. (From a
preparation in the Museum of the Royal College of Surgeons of England.)
The Levatores Costarum (Fig. 282), twelve in number on each side, are small
tendinous and fleshy bundles which arise from the extremities of the transverse
processes of the seventh cervical and eleven upper thoracic vertebrae, and, passing
obliquely downward and outward, are inserted into the upper border of the rib
below them, between the tubercle and the angle. The Inferior levatores divide
into two fasciculi, one of which is inserted as above described; the other fasciculus
passes down to the second rib below its origin; thus, each of the lower ribs receives
fibres from the transverse processes of two vertebrae.
Nerves. — The muscles of this group are supplied by the intercostal nerves.
OF THE THORAX 429
The Diaphragm (diaphragma, from did<ppa?fjta, a partition wall) (Figs. 284, 285,
and 286) is a thin, musculo-fibrous septum, consisting of muscular fibres externally,
which arise from the circumference of the thoracic cavity and pass upward and
inward to converge to a central tendon. It is placed obliquely at the junction of
the upper with the middle third of the trunk, and separates the thorax from the
abdomen, forming the floor of the former cavity and the roof of the latter. It is
elliptical, its longest diameter being from side to side; is somewhat fan-shaped, the
broad elliptical portion being horizontal, the narrow part, the crura, which repre-
sents the handle of the fan, vertical, and joined at right angles to the former. It
is from this circumstance that some anatomists describe it as consisting of two
portions, the upper or great muscle of the Diaphragm, and the lower or lesser
muscle. It arises from the whole of the internal circumference of the thorax,
being attached, in front, by fleshy fibres to the ensiform cartilage, sternal portion
of the Diaphragm (pars sternalis}; on either side, to the inner surface of the
cartilages and bony portions of the six or seven inferior ribs, costal portion (pars
costalis), interdigitating with the Transversalis; and behind, to two aponeurotic
arches, named the ligamentum arcuatum externum and the ligamentum arcuatum
internum, and by the crura, to the lumbar vertebrae, lumbar portion (pars lumbalis).
The fibres from these sources vary in length: those arising from the ensiform
appendix are very short and occasionally aponeurotic; those from the ligamenta
arcuata, and more especially those from the cartilages of the ribs at the side
of the chest, are longer, describe well-marked curves as they ascend, and finally
converge to be inserted into the circumference of the central tendon. Between
the sides of the muscular slip from the ensiform appendix and the cartilages of
the adjoining ribs the fibres of the Diaphragm are deficient, the interval being
filled by areolar tissue, covered on the thoracic side by the pleurae; on the abdom-
inal, by the peritoneum. This is, consequently, a weak point, and a portion of
the contents of the abdomen may protrude through it into the chest, forming a
phrenic or diaphragmatic hernia, or a collection of pus in the mediastinum may
descend through it, so as to point at the epigastrium. A triangular gap is some-
times seen between the fibres springing from the internal and those arising from
the external arcuate ligament. When it exists, the kidney is separated from the
pleura only by fatty and areolar tissue.
A congenital deficiency in the Diaphragm may produce diaphragmatic hernia;
in deficiency of the central tendon the hernia passes into the pericardial sac; in
deficiency of one of the lateral portions the hernia passes into the pleural sac.
There are five arcuate ligaments, two internal, two external, and one middle.
The Ligamentum Arcuatum Internum (arcus lumbocostalis medialis) is a tendinous
arch, thrown across the upper part of the Psoas magnus muscle, on each side of
the spine. It is connected, by one end, to the outer side of the body of the first or
second lumbar vertebra, being continuous with the outer side of the tendon of
the corresponding crus; and, by the other end, to the front of the transverse process
of the first, and sometimes also to that of the second, lumbar vertebra.
The Ligamentum Arcuatum Externum (arcus lumbocostalis lateralis) is the thick-
ened upper margin of the anterior lamella of the lumbar fascia; it arches across
the upper part of the Quadratus lumborum, being attached, by one extremity, to
the front of the transverse process of the first lumbar vertebra, and, by the other,
to the apex and lower margin of the^last rib.
The arch of fibrous tissue which connects the crura of the diaphragm in front
of the aorta is sometimes called the middle arcuate ligament. The Diaphragm is
connected to the spine' by two crura or pillars, which are situated on the bodies of
lumbar vertebrae, on each side of the aorta. The crura, at their origin, are ten-
dinous in structure; the right crus, larger and .longer than the left, arising from
the anterior common ligament and intervertebral substances of the three or four
430
upper lumbar vertebrae; the left, from the two upper lumbar vertebrae. These
tendinous portions of the crura pass forward and inward, and gradually con-
CESOPHAGUS
FORAMEN QUADRATUM
FOR VCNA CAVA
CENTRAL TENDON,
LEFT SIDE
AORTA CENTRAL TENDON.
RIGHT SIDE
FIG. 284. — The Diaphragm, seen from above. (Poirier and Charpy.)
FIG. 285.— The Diaphragm, viewed from in front. (Testut.)
verge to meet in the middle line, forming an arch, beneath which passes the
aorta, vena azygos major, and thoracic duct. From this tendinous arch muscular
fibres arise, which diverge, the outermost portion being directed upward and
OF THE THORAX
431
outward to the central tendon; the innermost decussating in front of the aorta
and then diverging, so as to surround the oesophagus before ending in the central
tendon. The fibres derived from the right crus are the most numerous and pass
in front of those derived from the left. His and Spalteholz teach that three crura
exist on each side — viz., the crus mediale, arising from the third and fourth lumbar
vertebrae; the crus intermedium, from the second and third lumbar vertebrae; and
the crus laterale, from the second or first lumbar vertebrae, and from the band of
fascia which is stretched between the lateral part of the body of the first lumbar
vertebra and the transverse process of the second lumbar vertebra in front of the
Psoas muscle.
The Central or Cordiform Tendon of the Diaphragm (centrum tendineum) is a thin
but strong tendinous aponeurosis, situated at the centre of the vault formed by
the muscle, immediately below the pericardium, with which it is partly blended.
It is shaped somewhat like a trefoil leaf, consisting of three divisions, or leaflets,
FIG. 286. — The Diaphragm, viewed from below. (Testut.)
separated from one another by slight indentations. The right leaflet is the largest;
the middle one, directed toward the ensiform cartilage, the next in size; and the
left, the smallest. In structure, the tendon is composed of several planes of fibres
which intersect one another at various angles, and unite into straight or curved
bundles — an arrangement which affords it additional strength.
The Openings. — The openings connected with the Diaphragm are three large
and several smaller apertures. The former are the aortic, the oesophageal, and the
opening for the vena cava.
The Aortic Opening (hiatus aorticus} is the lowest and the most posterior of the
three large apertures connected with this muscle, being at the level of the first
lumbar vertebra. It is situated slightly to the left of the middle line, immediately
in front of the bodies of the vertebrae; and is, therefore, behind the Diaphragm, not
in it. It is an osseo-aponeurotic aperture, formed by a tendinous arch thrown
across the front of the bodies of the vertebrae, from the crus on one side to that
on the other, and transmits the aorta, vena azygos major, and thoracic duct.
Sometimes the vena azygos major is transmitted upward through the right crus.
432 THE MUSCLES AND FASCIAE
Occasionally some tendinous fibres are prolonged across the bodies of the ver-
tebrae from the inner part of the lower end of the crura, passing behind the aorta,
and thus converting the opening into a fibrous ring.
The (Esophageal Opening (hiatus oesophageus) is situated at the level of the tenth
thoracic vertebrae; it is elliptical in form, oblique in direction, muscular in structure,
and, formed by the decussating fibres of the two crura, is placed above, and, at
the same time, anterior, and a little to the left of the preceding. It transmits the
oesophagus and vagus nerves and some small cesophageal arteries. The anterior
margin of this aperture is occasionally tendinous, being formed by the margin
of the central tendon. The posterior and lateral margins are thick and the gullet
is in contact with them for about half an inch. The right margin of the cesophageal
opening is particularly prominent and lies in the oesophageal groove on the posterior
surface of the left lobe of the liver.
The Opening for the Vena Cava or the Foramen Quadratum (foramen venae cavae)
is the highest opening, being about on the level of the disk between the eighth
and ninth thoracic vertebrae; it is quadrilateral in form, tendinous in structure, and
placed at the junction of the right and middle leaflets of the central tendon, its
margins being adherent to the wall of the inferior vena cava (postcava).
The right cms transmits the greater and lesser splanchnic nerves of the right
side; the left crus transmits the greater and lesser splanchnic nerves of the left
side, and the vena azygos minor. The gangliated cords of the sympathetic
usually enter the abdominal cavity by passing behind the internal arcuate liga-
ments.
Serous Membranes. — The serous membranes in relation with the Diaphragm are
four in number: three lining its upper or thoracic surface; one, its abdominal. The
three serous membranes on its upper surface are the pleura on either side and the
pericardium, which covers the middle portion of the tendinous centre. The
serous membrane covering the under surface of the Diaphragm is a portion of
the general peritoneal membrane of the abdominal cavity.
The Diaphragm is arched, being convex toward the chest and concave toward the
abdomen. The right portion forms a complete arch from before backward, being
accurately moulded over the convex surface of the liver, and having resting upon
it the concave base of the right lung. The left portion is arched from before back-
ward in a similar manner; but the arch is narrower in front, being encroached upon
by the pericardium, and lower than the right, at its summit, by about three-quarters
of an inch. It supports the base of the left lung, and covers the great end of the
stomach, the spleen, and left kidney. At its circumference the Diaphragm is
higher in the medial line of the body than at either side; but in the middle of the
thorax the central portion, which supports the heart, is on a lower level than the
two lateral portions.
Nerves. — The Diaphragm is supplied by the phrenic nerves, the lower inter-
costal nerves and the phrenic plexus of the sympathetic.
Actions. — The Intercostals are the chief agents in the movement of the ribs
in ordinary respiration. When the first rib is elevated and fixed by the Scaleni, the
External intercostals raise the other ribs, especially their forepart, and so increase
the capacity of the chest from before backward ; at the same time they evert their
lower borders, and so enlarge the thoracic cavity transversely. The Internal
intercostals, at the side of the thorax, depress the ribs and invert their lower
borders, and so diminish the thoracic cavity; but at the forepart of the chest these
muscles assist the External intercostals in raising the cartilages.1 The Levatores
1 The view of the action of the Intercostal muscles given in the text is that which is taught by Hutchinson
(Cycl. of Anat. and Phys., art. Thorax), and is usually adopted in our schools. It is, however, much dis-
puted. Hamberger believed that the External intercostals act as elevators of the ribs, or muscles of inspira-
tion, while the internal act in expiration. Haller taught that both sets of muscles act in common — viz., as muscles
of inspiration — and this view is adopted by many of the best anatomists of the Continent, and appears sup-
OF THE THORAX 433
costarum assist the External intercostals in raising the ribs. The Triangularis
sterni draws down the costal cartilages; it is therefore an expiratory muscle.
The Diaphragm is the principal muscle of inspiration. When in a condition
of rest the muscle presents a domed surface, concave toward the abdomen; and
consists of a circumferential muscular and a central tendinous part. When
the muscular fibres contract, they become less arched, or nearly straight, and
thus cause the central tendon to descend, and in consequence the level of the
chest-wall is lowered, the vertical diameter of the chest being proportionally
increased. In this descent the different parts of the tendon move unequally.
The left leaflet descends to the greatest extent; the right to a less extent, on
account of the liver; and the central leaflet the least, because of its connection to
the pericardium. In descending the Diaphragm presses on the abdominal viscera,
and so to a certain extent causes a projection of the abdominal wall; but in conse-
quence of these viscera not yielding completely, the central tendon becomes a fixed
point, and enables the circumferential muscular fibres to act from it, and so elevate
the lower ribs and expand the lower part of the thoracic cavity; and Duchenne
has shown that the Diaphragm has the power of elevating the ribs, to which it
is attached, by its contraction, if the abdominal viscera are in situ, but that if these
organs are removed, this power is lost. When at the end of inspiration the Dia-
phragm relaxes, the thoracic walls return to their natural position in consequence
of their elastic reaction and of the elasticity and weight of the displaced viscera.1
In all expulsive acts the Diaphragm is called into action, to give additional
power to each expulsive effort. Thus, before sneezing, coughing, laughing, and
crying, before vomiting, previous to the expulsion of the urine and faeces, or of
the foetus from the womb, a deep inspiration takes place.
The height of the Diaphragm is constantly varying during respiration, the
muscle being carried upward or downward from the average level ; its height also
varies according to the degree of distention of the stomach and intestines, and the
size of the liver. After a forced expiration, the right arch is on a level, in front,
with the fourth costal cartilage; at the side, with the fifth, sixth, and seventh
ribs; and behind, with the eighth rib, the left arch being usually from one to two
ribs' breadth below'the level of the right one. In a forced inspiration, it descends
from one to two inches; its slope would then be represented by a line drawn
from the ensiform cartilage toward the tenth rib. Prof. Wm. S. Forbes2 is of the
opinion that the Diaphragm is an appendage of the circulatory apparatus rather
than the chief agent in respiration. He maintains that the opening in the
vena cava is stationary and holds a constant relation to the ninth thoracic verte-
bra. He emphasizes the fact that the base of the pericardium is attached to the
central tendon of the Diaphragm, and on the anterior and left side. The muscular
fibres of the Diaphragm ascend upon and are attached to the pericardium. Pro-
longations of the fibrous pericardium pass upward as the pericardial ligaments.
These ligaments form fibrous planes reaching from each side of the central
tendon of the Diaphragm to the " bony apex of the thoracic line " and to the
fascia stretched across the thoracic apex, and they may be called the " superior
tendinous crura." It is thus evident that the deep cervical fascia is connected
to the lateral and superior parts of the pericardium. At birth the muscular
ported by many observations made on the human subject under various conditions of disease, and on living
animals after the muscles have been exposed under chloroform. The reader may consult an interesting paper
by Dr. Cleland in the Journal of Anat. and Phys., No. II., May, 1867, p. 209, On the Hutchinsonian Theory
of the Action of the Intercostal Muscles, who refers also to Henle, Luschka, Budge, and Baumler, Observa-
tions on the Action of the Intercostal Muscles, Erlangen, 1860. (In New Syd. Soc.'s Year-book for 1861, p. 69.)
Dr. W. W. Keen has come to the conclusion, from experiments made upon a criminal executed by hanging,
that the External intercostals are muscles of expiration, as they pulled the ribs down, while the Internal inter-
costals pulled the ribs up and are muscles of inspiration (Trans. Coll. Phys., Philadelphia, Third Series, vol. i.,
1875, p. 97).— ED. of loth English edition.
1 For a detailed description of the general relations of the Diaphragm, and its action, refer to Dr. Sibson's
Medical Anatomy. — ED. of 15th English edition.
J American Journal of the Medical Sciences, July, 1880. — ED. of 15th English edition.
28
434 THE MUSCLES AND FASCIAE
i
fibres of the Diaphragm contract at the first inspiration. The ductus arteriosus
is lodged in an elliptical opening of a tendinous scaffolding. The contractions
of the Diaphragm cause the tendinous scaffolding to compress the ductus arteri-
osus " and eventually close it." The chief agents in the compression are the
muscular fibres which pass from the Diaphragm to the pericardium. When the
lateral wings of the Diaphragm descend they tend to form a vacuum in the thorax
and thus assist the venous circulation.
" The descent of the Diaphragm is not necessary to respiration," but it " is
necessary in order to protect the heart from the movement of surrounding
viscera, and in order to promote the free circulation of the blood through the
vessels forming the cardiac roots."
Muscles of Inspiration and Expiration. — The muscles which assist the action
of the Diaphragm in ordinary tranquil inspiration are the Intercostals and the
Levatores costarum, as above stated, and the Scaleni. When the need for more
forcible action exists, the shoulders and the base of the scapula are fixed, and then
the powerful muscles of forced inspiration come into play; the chief of these are
the Trapezius, the Pectoralis minor, the Serratus posticus superior and inferior,
and the Rhomboidei. The lower fibres of the Serratus magnus may possibly assist
slightly in dilating the chest by raising and everting the ribs. The Sterno-mastoid
also, when the head is fixed, assists in forced inspiration by drawing up the sternum
and by fixing the clavicle, and thus affording a fixed point for the action of the
muscles of the chest. The Ilio-costalis and Quadratus lumborum assist in forced
inspiration by fixing the last rib.
The ordinary action of expiration is hardly effected by muscular force, but
results from a return of the walls of the thorax to a condition of rest, owing to
their own elasticity and to that of the lungs. Forced expiratory actions are per-
formed mainly by the flat muscles (Obliqui and Transversalis) of the abdomen,
assisted by the Rectus. Other muscles of forced expiration are the Internal
intercostals and Triangularis sterni (as above mentioned).
III. MUSCLES OF THE ABDOMEN. .
The muscles of the abdomen may be divided into two groups: 1. The super-
ficial muscles of the abdomen. 2. The deep muscles of the abdomen.
1. The Superficial Muscles of the Abdomen.
The Muscles in this region are, the
External Oblique. Transversalis.
Internal Oblique. Rectus.
Pyramidalis.
Dissection (Fig. 287). — To dissect the abdominal muscles, make a vertical incision from the
ensiform cartilage to the symphysis pubis; a second incision from the umbilicus obliquely upward
and outward to the outer surface of the chest, as high as the lower border of the fifth or sixth
rib; and a third, commencing midway between the umbilicus and pubes, transversely outward
to the anterior superior iliac spine, and along the crest of the ilium as far as its posterior third.
Then reflect the three flaps included between these incisions from within outward, in the lines
of direction of the muscular fibres. If necessary, the abdominal muscles may be made tense
by inflating the peritoneal cavity through the umbilicus.
Superficial Fascia. — The superficial fascia of the abdomen consists, over the
greater part of the abdominal wall, of a single layer of fascia, which contains a
variable amount of fat ; but as this layer approaches the groin it is easily divisible
into two layers, between which are found the superficial vessels and nerves and
the superficial inguinal lymphatic glands. The superficial layer of the superficial
OF THE ABDOMi:X
435
sory ligament of
superficial layer
superficial fascia over the
below, it blends with the
inguinal
hernia.
FIG. 287. — Dissection of abdomen.
fascia, or the fascia of Camper, is thick, areolar in texture, containing adipose tissue
in its meshes, the quantity of which varies in different subjects. Below it passes
over Poupart's ligament, and is continuous with the outer layer of the superficial
fascia of the thigh. In the male this fascia is continued over the penis and outer sur-
face of the cord to the scrotum, where it helps to
form the dartos. As it passes to the scrotum it
changes its character, becoming thin, destitute of
adipose tissue, and of a pale hue, it has a reddish
color, and in the scrotum it acquires some invol-
untary muscular fibres. From the scrotum it may
be traced backward to be continuous with the
superficial fascia of the perinseum. In the female
this fascia is continued into the labia majora.
The deep layer of the superficial fascia or the fascia
of Scarpa, is thinner and more membranous in
character than the superficial layer. In the mid-
dle line it is intimately adherent to the linea alba
and to the symphysis pubis, and is prolonged on section of\
to the dorsum of the penis, forming the suspen-
the penis; above, it joins the
and is continuous with the
rest of the trunk;
fascia lata of the
thigh a little below Poupart's ligament; and
below and internally it is continued over the
penis and spermatic cord to the scrotum, where
it helps to form the dartos. From the scrotum
it may be traced backward to be continuous with the deep layer of the super-
ficial fascia of the perinaeum. In the female it is continued into the labia
majora.
Deep Fascia. — The deep fascia invests the external oblique muscle, but is so
thin over the aponeurosis of the muscle as to be scarcely recognizable.
The External or Descending Oblique Muscle (m. obliquus externus abdominis)
(Fig. 288) is situated on the side and forepart of the abdomen ; being the largest
and the most superficial of the three flat muscles in this region. It is broad, thin,
and irregularly quadrilateral, its muscular portion occupying the side, its aponeu-
rosis the anterior wall, of the abdomen. It arises, by eight fleshy digitations,
from the external surface and lower borders of the eight inferior ribs; these
digitations are arranged in an oblique line running downward and backward;
the upper ones being attached close to the cartilages of the corresponding ribs;
the lowest, to the apex of the cartilage of the last rib; the intermediate ones, to
the ribs at some distance from their cartilages. The five superior serrations
increase in size from above downward, and- are received between corresponding
processes of the Serratus magnus; the three lower ones diminish in size from
above downward, receiving between them corresponding processes from the Latis-
simus dorsi. From these attachments", the fleshy fibres proceed in various direc-
tions. Those from the lowest ribs pass nearly vertically downward, to be inserted
into the anterior half of the outer lip of the crest of the ilium ; the middle and
upper fibres, directed downward and forward, terminate in an aponeurosis, oppo-
site a line drawn from the prominence of the ninth costal cartilage to the anterior
superior spinous process of the ilium.
Aponeurosis of External Oblique. — The aponeurosis of the external oblique is a
thin, but strong membranous aponeurosis, the fibres of which are directed
436
THE MUSCLES AND FASCIA
obliquely downward and inward. It is joined with that of the opposite muscle
along the median line, covers the whole of the front of the abdomen; above, it is
connected with the lower border of the Pectoralis major; below, its fibres are closely
External abdo-
minal ring.
Gimbernafs—,
ligament. I
fPubes.
FIG. 288. — The External oblique muscle.
aggregated together, and extend obliquely across from the anterior superior spine
of the ilium to the spine of the os pubis and the linea ilio-pectinea. In the median
line it interlaces with the aponeurosis of the opposite muscle, forming the linea
alba, which extends from the ensiform cartilage to the symphysis pubis.
That portion of the aponeurosis which extends between the anterior superior
spine of the ilium and the spine of the os pubis is a broad band, folded inward,
and continuous below with the fascia lata; it is called Poupart's ligament or the
ligament of Fallopius. The portion which is reflected from Poupart's ligament
at the spine of the os pubis along the pectineal line is called Gimbernat's ligament.
From the point of attachment of the latter to the pectineal line, a few fibres
OF THE ABDOMEN
437
pass upward and inward, behind the inner pillar of the ring, to the linea alba.
They diverge as they ascend, and form a thin, triangular, fibrous layer, which is
called the triangular fascia of the abdomen or Colles's ligament (ligamentum
inguinale reflexum). The point of the triangle is at the origin of Colles's ligament ;
the base is at the linea alba. Colles's ligament is in front of the conjoined tendon,
the Rectus muscle, and the Pyramidalis muscle.
In the aponeurosis of the External oblique, immediately above the crest of the
os pubis, is a triangular opening, the external abdominal ring, formed by a separa-
tion of the fibres of the aponeurosis in this situation.
POUPART'S
LIGAMENT
INTERCOLUMNAR
FIBRES
GIMBEflNAT'S
LIGAMENT
SAPHENOUS
OPENING
FEMORAL
VEIN
LONG
SAPHENOUS
VEIN
EXTERNAL
ABDOMINAL
RING
CRUS
SUPERIOR
FIG. 289. — Right external abdominal ring and saphenous opening in the male. (Spalteholz.)
Relations. — By its external surface, with the superficial fascia, superficial epi-
gastric and circumflex iliac vessels, and some cutaneous nerves; by its internal
surface, with the Internal oblique, the lower part of the eight inferior ribs, and
Intercostal muscles, the Cremaster, the spermatic cord in the male, and round liga-
ment in the female. Its posterior border, extending from the last rib to the crest
of the ilium, is fleshy throughout and free; it is occasionally overlapped by the
Latissimus dorsi, though generally a triangular interval exists between the two
muscles near the crest of the ilium, in which is seen a portion of the internal
oblique. This triangle, Petit's triangle (trigonum lumbale), is therefore bounded
in front by the External oblique, behind by the Latissimus dorsi, below by the
crest of the ilium, while its floor is formed by the Internal oblique (Fig. 288).
The following parts of the aponeurosis of the External oblique muscle require
to be further described — viz., the external abdominal ring, the intercoiumnar fibres
and fascia, Poupart's ligament, Gimbernat's ligament, and the triangular fascia of
the abdomen.
The External Abdominal Ring (annulus inguinalis subcutaneous) (Figs. 289 and
292). — Just above and to the outer side of the crest of the os pubis an interval is seen
438 THE MUSCLES AND FASCIA
in the aponeurosis of the External oblique, called the external abdominal ring. The
aperture is oblique in direction, somewhat triangular in form, and corresponds with
the course of the fibres of the aponeurosis. It usually measures from base to apex
about an inch, and transversely about half an inch. It is bounded below by the
crest of the os pubis; above, by a series of curved fibres, the external spermatic or
the intercolumnar fibres which pass across the upper angle of the ring, so as to
increase its strength; and on each side, by the margins of the opening in the
aponeurosis, which are called the columns or pillars of the ring.
The External Pillar or inferior crus (crus inferius) is inferior from the obliquity
of its direction. It is stronger than the internal pillar; it is formed by that
portion of Poupart's ligament which is inserted into the spine of the os pubis; it is
curved so as to form a kind of groove, upon which the spermatic cord rests.
The Internal Pillar or superior crus (crus superius) is a broad, thin, flat band,
which is attached to the front of the symphysis pubis, interlacing with its 'fellow
of the opposite side.
The external abdominal ring gives passage to the spermatic cord in the male
(funiculus spermaticus) and round ligament in the female (ligamentum teres uteri) :
it is much larger in men than in women, on account of the large size of the sper-
matic cord, and hence the greater frequency of inguinal hernia in men.
Intercolumnar Fibres (fibrae intercrurales) (Fig. 289). — The intercolumnar fibres
are a series of curved tendinous fibres, which arch across the lower part of
the aponeurosis of the External oblique. They have received their name from
stretching across between the two pillars of the external ring, describing a curve
with the convexity downward. They are much thicker and stronger at the outer
margin of the external ring, where they are connected to the outer third of Pou-
part's ligament, than internally, where they are inserted into the linea alba. They
are more strongly developed in the male than in the female. The inter-
columnar fibres increase the strength of the lower part of the aponeurosis,
and prevent the divergence of the pillars from one another.
These intercolumnar fibres as they pass across the external abdominal ring
are themselves connected together by delicate fibrous tissue, thus forming a fascia,
which as it is attached to the pillars of the ring covers it in, and is called the
intercolumnar fascia or the external spermatic fascia. This intercolumnar fascia
is continued down as a tubular prolongation around the outer surface of the
cord and testis or of the round ligament, and encloses them in a distinct sheath.
The sac of an inguinal hernia, in passing through the external abdominal ring, receives an
investment from the intercolumnar fascia.
If the finger is introduced a short distance into the external abdominal ring
and the limb is then extended and rotated outward, the aponeurosis of the External
oblique, together with the iliac portion of the fascia lata, will be felt to become
tense, and the external ring much contracted; if the limb is, on the contrary, flexed
upon the pelvis and rotated inward, this aponeurosis will become lax and the
external abdominal ring sufficiently enlarged to admit the finger with compara-
tive ease; hence the patient should always be put in the latter position when the
taxis is applied for the reduction of an inguinal hernia in order that the abdominal
walls may be relaxed as much as possible.
Poupart's Ligament (ligamentum inguinale). — The portion of Poupart's ligament
in front of the crural ring is called the superficial crural arch. Poupart's ligament
is the lower border of the aponeurosis of the External oblique muscle, and extends
from the anterior superior spine of the ilium to the pubic spine. From this
latter point it is reflected outward to be attached to the pectineal line for about
half an inch, forming Gimbernat's Ligament. Its general direction is curved down-
OF THE ABDOMEN
ward toward the thigh, where it is continuous with the fascia lata. Its outer half
is rounded and oblique in direction. Its inner half gradually widens at its attach-
ment to the os pubis, is more horizontal in direction, and lies beneath the spermatic
cord. Nearly the whole of the space included between the crural arch and the
innominate bone is filled in by the parts which descend from the abdomen into
the thigh (Fig. 297). These will be referred to again on a subsequent page.
Gimbernat's t Ligament (ligamentum lacunare) (Figs. 289 and 297). — Gimbernat's
ligament is that part of the aponeurosis of the External oblique muscle which is
reflected upward and outward from the spine of the os pubis to be inserted into the
pectineal line. It is about half an inch in length, larger in the male than in the
female, almost horizontal in direction in the erect posture, and of a triangular form
with the base directed outward. Its base, or outer margin, is concave, thin, and
sharp, and lies in contact with the crural sheath, forming the inner boundary of
the femoral or crural ring (annulus femoralis). Its apex corresponds to the spine
of the os pubis. Its posterior margin is attached to the pectineal line, and is con-
tinuous with the pubic portion of the fascia lata. Its anterior margin is continuous
with Poupart's ligament. Its surfaces are directed upward and downward.
Triangular Fascia or Colles's Ligament (ligamentum inguinal reflexum). — The
triangular fascia of the abdomen is a layer of tendinous fibres of a triangular
shape, which is attached by its apex to the pectineal line, where it is continuous
with Gimbernat's ligament. It passes inward beneath the spermatic cord, and
expands into a somewhat fan-shaped fascia, lying behind the inner pillar of the
external abdominal ring, and in front of the conjoined tendon, and interlaces with
the ligament of the other side at the linea alba.
Ligament of Cooper (Fig. 297). — This is a strong ligamentous band, which was
first described by Sir Astley Cooper. It extends upward and backward from the
base of Gimbernat's ligament along the ilio-pectineal line, to which it is attached.
It is strengthened by the fascia transversalis, by the pectineal aponeurosis, and
by a lateral expansion from the lower attachment of the linea alba (adminiculum
linecp albce).
Suspensory Ligament of the Penis (ligamentum fundiforme penis). — The suspen-
sory ligament of the penis arises from the linea alba, the anterior portion of
the sheath of the Rectus muscle, and the superficial fascia. It splits into two
portions, blends with the inserting fascia of the penis, and passes into the scrotum.
Suspensory Ligament of the Clitoris (ligamentum fundiforme clitoridis). — The
suspensory ligament of the clitoris corresponds in the female to the suspen-
sory ligament of the penis in the male.
Dissection — Detach the External oblique by dividing it across, just in front of its attach-
ment to the ribs, as far as its posterior border, and separate it below from the crest of the ilium
as far as the anterior superior spine; then separate the muscle carefully from the Internal oblique,
which lies beneath, and turn it toward the opposite side.
The Internal or Ascending Oblique Muscle (m. obliqum internus abdominis)
(Fig. 290), thinner and smaller than the preceding, beneath which it lies, is of
an irregularly quadrilateral form, and is situated at the side and forepart of the
abdomen. It arises, by fleshy fibres, from the outer half of Poupart's ligament,
being attached to the groove on its upper surface; from the anterior two-thirds
of the middle lip of the crest of the ilium, and from the posterior lamella of the
lumbar fascia (Fig. 294). From this origin the fibres diverge : those from Poupart's
ligament, few in number and paler in color than the rest, arch downward and
inward across the spermatic cord in the male and the round ligament in the
female, and, becoming tendinous, are inserted, conjointly with those of the Trans-
versalis, into the crest of the os pubis and pectineal line, to the extent of half an inch
or more, forming what is known as the conjoined tendon of the Internal oblique and
440
THE MUSCLES AND FASCIAE
Transversalis ; those from the anterior third of the iliac origin are horizontal in
their direction, and, becoming tendinous along the lower fourth of the linea
semilunaris, pass in front of the Rectus muscle to be inserted into the linea alba;
those which arise from the middle third of the origin from the crest of the
ilium pass obliquely upward and inward, and terminate in an aponeurosis which
divides at the outer border of the Rectus muscle into two lamellae (Fig. 295),
which are continued forward, in front and behind this muscle, to the linea alba,
the posterior lamella being also connected to the cartilages of the seventh, eighth,
and ninth ribs; the most posterior fibres pass almost vertically upward, to be
inserted into the lower borders of the cartilages of the three lower ribs, being con-
tinuous with the Internal intercostal muscles.
Conjoined tendon.
CREMASTER.
FIG. 290. — The Internal oblique muscle.
The conjoined tendon of the Internal oblique and Transversalis is inserted into
the crest of the os pubis and pectineal line, immediately behind the external
abdominal ring, serving to protect what would otherwise be a weak point in the
abdominal wall. Sometimes this tendon is insufficient to resist the pressure from
within, and is carried forward in front of a protrusion through the external ring,
forming one of the coverings of direct inguinal hernia; or the hernia forces its way
through the fibres of the conjoined tendon. The conjoined tendon is sometimes
divided into an outer and an inner portion — the former being termed the liga-
ment of Hesselbach; the latter, the ligament of Henle (Fig. 291). See pages 444
and 446.
OF THE ABDOMEN
441
Aponeurosis of Internal Oblique.— The aponeurosis of the Internal oblique is
continued forward to the middle line of the abdomen, where it joins with the
aponeurosis of the opposite muscle at the linea alba, and extends from the margin
of the thorax to the os pubis. At the outer margin of the Rectus muscle this
aponeurosis, for the upper three-fourths of its extent, divides into two lamellae,
which pass, one in front and the other behind the muscle, enclosing it in a kind of
sheath, and reuniting on its inner border of the linea alba; the anterior layer is
blended with the aponeurosis of the External oblique muscle ; the posterior layer
with that of the Transversalis. Along the lower fourth the aponeurosis passes
altogether in front of the Rectus without any separation. Where the aponeurosis
SEMILUNAR FOLD
OF DOUGLAS
TRANSVERSALIS
RECTUS
ABDOMINIS
DEEP EPI-
GASTRIC ARTERY
AND VEIN
INTERNAL
OBLIQUE
LiGAMENT OF HENLC
LIGAMENT OF HESSELBACH
FIG. 291. — The deep epigastric artery and veins, ligament of Henle and ligament of Hesselbach, seen
from in front. (Modified from Braune.)
ceases to split, and passes altogether in front of the Rectus muscle, a deficiency is
left in the sheath of the muscle behind; this is marked above by a sharp lunated
margin having its concavity downward. This is known as the semilunar fold of
Douglas (linea semicircularis) (Fig. 292).
Relations. — By its external surface, with the External oblique, Latissimus dorsi,
spermatic cord, and external ring; by its internal surface, with the Transversalis
muscle, the lower intercostal vessels and nerves, the ilio-hypogastric and the ilio-
inguinal nerves. Near Poupart's ligament it lies on the fascia transversalis,
internal ring, and spermatic cord. Its lower border forms the upper boundary
of the inguinal canal.
The Cremaster muscle (Fig. 290) is a thin, muscular layer, composed of a num-
ber of fasciculi which arise from the "inner part of Poupart's ligament, where its
fibres are continuous with those of the Internal oblique and also occasionally with
the Transversalis. It passes along the outer side of the spermatic cord, descends
with it through the external abdominal ring upon the front and sides of the cord,
and forms a series of loops which differ in thickness and length in different sub-
jects. Those at the upper part of the cord are exceedingly short, but they become
in succession longer and longer, the longest reaching down as low as the testicle,
where a few are inserted into the tunica vaginalis. These loops are united together
by areolar tissue, and form a thin covering over the cord and testis, the middle
442
THE MUSCLES AND FASCIAE
spermatic fascia (fascia cremastericd). The fibres ascend along the inner side of
the cord, and are inserted by a small pointed tendon into the crest of the os
pubis and front of the sheath of the Rectus muscle.
LINEA ALBA
POSTERIOR LEAF
OF SHEATH OF
RECTUS ABDOMINIS
LINEA SEMILUNARIS
TRANSVERSALIS
SEMILUNAR FOLD
OF DOUGLAS
RECTUS ABDOMINIS
(cut through)
ANTERIOR LEAF
F SHEATH OF
RECTUS ABDOMINIS
FIG. 292. — The muscles of the abdomen, showing the semilunar fold of Douglas. Viewed from in front.
(Spalteholz.)
It will be observed that the origin and insertion of the Cremaster is precisely
similar to that of the lower fibres of the Internal oblique. This fact affords an easy
explanation of the manner in which the testicle and cord are invested by this
muscle. At an early period of foetal life the testis is placed at the lower and back
part of the abdominal cavity, but during its descent toward the scrotum, which
takes place before birth, it passes beneath the arched fibres of the Internal oblique.
In its passage beneath this muscle some fibres are derived from its lower part
which accompany the testicle and cord into the scrotum. It occasionally happens
OF THE ABDOMEN
443
that the loops of the Cremaster surround the cord, some lying behind as well as in
front. It is probable that under these circumstances the testis, in its descent,
passed through instead of beneath the fibres of the Internal oblique.
In the descent of an oblique inguinal hernia, which takes the same course as
the spermatic cord, the Cremaster muscle forms one of its coverings. This muscle
becomes largely developed in cases of hydrocele and large old scrotal hernia. The
Cremaster muscle is found only in the male, but almost constantly in the female
Linea alba.
FIG. 293. — The Transversalis, Rectus, and Pyramidalis muscles.
a few muscular fibres may be seen on the surface of the round ligament, which
correspond to this muscle, and in cases of oblique inguinal hernia in the female a
considerable amount of muscular fibre may be found covering the sac.
Dissection. — Detach the Internal oblique in order to expose the Transversalis beneath. This
may be effected by dividing the muscle, above, at its attachment to the ribs; below, at its con-
nection with Poupart's ligament and the crest of the ilium; and behind, by a vertical incision
444 THE MUSCLES AND FASCIA
extending from the last rib to the crest of the ilium. The muscle should previously be made
tense by drawing upon it with the fingers of the left hand, and if its division is carefully effected,
the cellular interval between it and the Transversalis, as well as the direction of the fibres of the
latter muscle, will afford a. clear guide to their separation; along the crest of the ilium the cir-
cumflex iliac vessels are interposed between them, and form an important guide in separating
them. The muscle should then be thrown inward toward the linea alba.
The Transversalis Muscle (m. transversus abdominis) (Fig. 293), so called
from the direction of its fibres, is the most internal flat muscle of the abdomen,
being placed immediately beneath the Internal oblique. It arises by fleshy fibres
from the outer third of Poupart's ligament; from the inner lip of the crest of the
ilium for its anterior three-fourths; from the inner surface of the cartilages of the
six lower ribs, interdigitating with the Diaphragm; and from the lumbar fascia
(Fig. 294), which may be regarded as the posterior aponeurosis of the muscle.
The muscle terminates in front in a broad aponeurosis, the lower fibres of
which curve downward and inward, and are inserted, together with those of the
Internal oblique, into the lower part of the linea alba, the crest of the os pubis
and pectineal line forming what is known as the conjoined tendon of the Internal
oblique and Transversalis. The lowermost fibres help to form the posterior wall
of the inguinal canal. Throughout the rest of its extent the aponeurosis passes
horizontally inward, and is inserted into the linea alba, its upper three-fourths
passing behind the Rectus muscle, blending with the posterior lamella of the
Internal oblique; its lower fourth passing in front of the Rectus. The external
portion of the lower fibres of the conjoined tendon is known as the ligament of
Hesselbach (Fig. 291) (ligamentum interfoveolare}; the internal portion as the liga-
ment of Henle (Fig. 291) (falx inguinalis}.
Relations. — By its external surface, with the Internal oblique, the lower inter-
costal nerves, and the inner surface of the cartilages of the lower ribs; by its
internal surface, "with the fascia transversalis, which separates it from the periton-
eum. Its lower border forms the upper boundary of the inguinal canal.
Dissection. — To expose the Rectus muscle, open its sheath by a vertical incision extending
from the margin of the thorax to the os pubis, and then reflect the two portions from the surface
of the muscle, which is easily done, excepting at the linese transversse, where so close an adhesion
exists that the greatest care is requisite in separating them. Now raise the outer edge of the
muscle, in order to examine the posterior layer of the sheath. By dividing the muscle in the
centre, and turning its lower part downward, the point where the posterior wall of the sheath
terminates in a thin curved margin will be seen.
The Rectus Abdominis (Figs. 291, 293 and 295) is a long flat muscle, which
extends along the whole length of the front of the abdomen, being separated from
its fellow of the opposite side by the linea alba. It is much broader, but thinner,
above than below, and arises by two tendons, the external or larger being attached
to the crest of the os pubis, the internal, smaller portion interlacing with its fellow of
the opposite side, and being connected with the ligaments covering the front of the
symphysis pubis. The fibres as'cend, and the muscle is inserted by three portions of
unequal size into the cartilages of the fifth, sixth, and seventh ribs. The upper por-
tion, attached principally to the cartilage of the fifth rib, usually has some fibres of
insertion into the anterior extremity of the rib itself. Some fibres are occasionally
connected with the costo-xiphoid ligaments and side of the ensiform cartilage.
The Rectus muscle is traversed by tendinous intersections, three in number,
which have received the name of linese transversae. One of these is usually
situated opposite the umbilicus, and two above that point; of the latter, one
corresponds to the extremity of the ensiform cartilage, and the other to the inter-
val between the ensiform cartilage and the umbilicus. These intersections pass
transversely or obliquely across the muscle in a zigzag course; they rarely extend
completely through its substance, sometimes they pass only half-way across it, and
are intimately adherent in front to the sheath in which the muscle is enclosed.
OF THE ABDOMEN
445
Sometimes one or two additional lines may be seen, one usually below the
umbilicus; the position of the other, when it exists, is variable. These addi-
tional lines are for the most part incomplete.
FIG. 294. — A transverse section of the abdomen in the lumbar region.
The Rectus is enclosed in a sheath, the rectus sheath (vagina m. recti abdominis)
(Figs. 294 and 295), formed by the aponeurosis of the Oblique and Transversalis
SHEATH OF
RECTUS ABOOMINIS
(anterior leaf)
Posterior leaf Anterior leaf
SHEATH OF RECTUS ABDOMINIS
FIG. 295. — Transition of the tendon of the right internal oblique into the sheath of the rectus. (Spalteholz.)
muscles, which are arranged in the following manner. When the aponeurosis of the
Internal oblique arrives at the outer margin of the Rectus it divides into two lamellae,
446 THE MUSCLES AND FASCIAE
one of which passes in front of the Rectus, blending with the aponeurosis of the
External oblique ; the other, behind it, blending with the aponeurosis of the Trans-
versalis; and these, joining again at its inner border, are inserted into the linea alba.
This arrangement of the aponeuroses exists along the upper three-fourths of the
muscle : at the commencement of the lower fourth, the posterior wall of the sheath
terminates in a thin curved margin, the semilunar fold of Douglas (linea semicir-
cularis) (Fig. 292), the concavity of which looks downward toward the pubes; the
aponeuroses of all three muscles passing in front of the Rectus without any sepa-
ration. A very thin aponeurotic layer does pass behind the lower one-fourth of
the muscle, but it is trivial as compared with the thickness of the layer behind the
upper three-fourths of the muscle. This sudden thinning causes the semilunar
fold of Douglas. The extremities of the fold of Douglas descend as pillars to the
os pubis. The inner pillar is attached to the symphysis pubis; the outer pillar
passes downward as a distinct band on the inner side of the internal abdominal
ring to join with the outer fibres of the conjoined tendon, and assist to form
the ligament of Hesselbach (ligamentum inter foveolare) (Fig. 291). There its fibres
divide into two sets, internal and external; the internal fibres are attached to the
ascending ramus of the os pubis and the pectineal fascia; the external ones pass to
the Psoas fascia, to the deep surface of Poupart's ligament, and to the tendon of
the Transversalis on the outer side of the ring. The Rectus muscle, in the situation
where its sheath is deficient, is separated from the peritoneum by the transversalis
fascia. The convex outer border of the Rectus muscle corresponds to the linea
semilunaris.
The Pyramidalis is a small muscle, triangular in shape, placed at the lower
part of the abdomen, in front of the Rectus, and contained in the same sheath
with that muscle. It arises by tendinous fibres from the front of the os pubis
and the anterior pubic ligament ; the fleshy portion of the muscle passes upward,
diminishing in size as it ascends, and terminates by a pointed extremity, which is
inserted into the linea alba, midway between the umbilicus and the os pubis. This
muscle is sometimes found wanting on one or both sides; the lower end of the
Rectus then becomes proportionately increased in size. Occasionally it has been
found double on one side, or the muscles of the two sides are of unequal size.
Sometimes its length exceeds what is stated above.
Besides the Rectus and Pyramidalis muscles, the sheath of the Rectus contains
the superior and deep epigastric arteries, the terminations of the lumbar arteries
and of the lower intercostal arteries and nerves.
Nerves. — The abdominal muscles are supplied by the lower intercostal nerves.
The Transversalis and Internal oblique also receive filaments from the hypogastric
branch of the ilio-hypogastric and sometimes from the ilio-inguinal. The Cremas-
ter is supplied by the genital branch of the genito-femoral.
In the description of the abdominal muscles mention has frequently been made
of the linea alba, lineae semilunares, and lineae transversae; when the dissection of
the muscles is completed these structures should be examined.
The Linea Alba (Figs. 292, 293, and 294). — The linea alba is a tendinous raphe
seen along the middle line of the abdomen, extending from the ensiform cartilage to
the symphysis pubis, to the superior pubic ligament of which it is attached. It
is placed between the inner borders of the Recti muscles, and is formed by the
blending of the aponeuroses of the Obliqui and Transversales muscles. It is
narrow below, corresponding to the narrow interval existing between, the Recti;
but broader above, as these muscles diverge from one another in their ascent,
becoming of considerable breadth when there is great distention of the abdomen
from pregnancy or ascites. It presents numerous apertures for the passage of
vessels and nerves: the largest of these is the umbilicus (Fig. 296). The umbilicus
is a fibrous ring formed by the fibres of the aponeurosis of the linea alba, is filled
with scar tissue; in the fcetus transmits the umbilical vein, the two hypogas-
OF THE ABDOMEN
447
UMBILICAL
VEIN
LINEA ALBA
NTERVASCULAR
FOSSA
YPOGASTRIC
RTERY
FIG. 296. — The umbilicus of the foetus
seen from within the abdomen. (Poirier
and Charpy.)
trie arteries, the allantoic duct, and the vitello-intestinal duct; but in the
adult is obliterated, the cicatrix being stronger than the neighboring parts; hence
umbilical hernia occurs in the adult near the umbilicus, whilst in the foetus it occurs
at the umbilicus. The remains of the foetal structures are cord-like in character,
and they diverge from the umbilicus within the
abdomen. The remains of the umbilical vein con-
stitute the round ligament of the liver, and this
cord passes upward (Fig. 296). The remains of
the hypogastric arteries pass downward (Fig. 296).
The remains of the allantois become the urachus,
which passes to the summit of the bladder (Fig.
296). The depression of the umbilicus was
created by the urachus. The linea alba is in re-
lation, in front, with the integument, to which it
is adherent, especially at the umbilicus; behind,
it is separated from the peritoneum by the trans-
versalis fascia; and below, by the urachus, and
the bladder when that organ is distended.
The Lineae Semilunares (Figs. 288 and 292).—
The linese semilunares are two curved tendinous
lines placed one on each side of the linea alba.
Each corresponds with the outer border of the
Rectus muscle, extends from the cartilage of the
ninth rib to the pubic spine, and is formed by the
aponeurosis of the Internal oblique at its point of division to enclose the Rectus,
where it is reinforced in front by the External oblique and behind by the Trans-
versalis.
The Lineae Transversse (inscriptiones tendineae) (Fig. 288). — The linese trans-
verses are narrow transverse lines which intersect the Recti muscles, as already
mentioned; they connect the linese semilunares with the linea alba.
Actions. — The abdominal muscles perform a threefold action:
When the pelvis and thorax are fixed, they compress the abdominal viscera, by
constricting the cavity of the abdomen, in which action they are materially assisted
by the descent of the Diaphragm. By these means the foetus is expelled from the
uterus, the faeces from the rectum, the urine from the bladder, and the contents of
the stomach in vomiting.
If the pelvis and spine are fixed, these muscles compress the lower part of the
thorax, materially assisting expiration. If the pelvis alone is fixed, the thorax is
bent directly forward when the muscles of both sides act, or to either side when
those of the two sides act alternately, rotation of the trunk at the same time taking
place to the opposite side.
If the thorax is fixed, these muscles, acting together, draw the pelvis upward,
as in climbing; or, acting singly, they draw the pelvis upward, and bend the
vertebral column to one side or the other. The Recti muscles, acting from below,
depress the thorax, and consequently flex the vertebral column ; when acting from
above, they flex the pelvis upon the vertebral column. The Pyramidalis are
tensors of the linea alba.
The Transversalis Fascia (fascia transversalis}. — The fascia transversalis is a
thin aponeurotic membrane which lies between the inner surf ace of the Transversalis
muscle and the extra-peritoneal fat. It forms part of the general layer of fascia
which lines the interior of the abdominal and pelvis cavities, and is directly continu-
ous with the iliac and pelvic fasciae. In the inguinal region the transversalis fascia is
thick and dense in structure, and joined by fibres from the aponeurosis of the Trans-
versalis muscle, but it becomes thin and cellular as it ascends to the Diaphragm,
and blends with the fascia covering this muscle. In front, it unites across the
44S
THE MUSCLES AND FASCIA
middle line with the fascia on the opposite side of the body, and behind it becomes
lost in the fat which covers the posterior surfaces of the kidneys. Below, it has
the following attachments: posteriorly, it is connected to the whole length of the
crest of the iiium, between the attachments of the Transversalis and Iliacus
muscles; between the anterior superior spine of the ilium and the femoral vessels
it is connected to the posterior margin of Poupart's ligament, and- is there con-
tinuous with the iliac fascia. Internal to the femoral vessels it is thin and attached
to the os pubis and pectineal line, behind the conjoined tendon, with which it is
united; and, corresponding to the point where the femoral vessels pass into the
thigh, this fascia descends in front of them, forming the anterior wall of the crural
sheath. Beneath Poupart's ligament it is strengthened by a band of fibrous tissue,
which is only loosely connected to Poupart's ligament, and is specialized as the
deep crural arch. The spermatic cord in the male and the round ligament in the
female pass through this fascia; the point where they pass through is called the
internal abdominal ring. This opening is not visible externally, owing to a pro-
longation of the transversalis fascia on these structures, forming the infundibuliform
fascia.
The internal or deep abdominal ring (annulus inguinalis abdominis} (Figs. 291
and 297) is situated in the transversalis fascia, midway between the anterior
TRANSVERSALIS
FASCIA
INTERNAL
ABDOMINAL
RING
CRURAL NERVE
FEMORAL ARTERY.
ILIAC FASCIA
GIMBERNAT'S
LIGAMENT
CRURAL
SEPTUM
COOPER'S
LIGAMENT
FIG. 297.- The relation of the femoral and internal abdominal rings, seen from within the abdomen after
removal of the peritoneum. (Poirier and Charpy.)
superior spine of the ilium and the symphysis pubis, and about half an inch above
Poupart's ligament. It is of an oval form, the extremities of the oval directed
upward and downward, varies in size in different subjects, and is much larger in
the male than in the female. Its lower border is strengthened by the collection of
fibres called Hesselbach's ligament, lying directly in front of the deep epigastric
artery. It is the outer portion of the conjoined tendon fused with the outer
pillar of the semilunar fold of Douglas. The internal ring is bounded, above
and externally, by the arched fibres of the Transversalis; below and internally,
by the deep epigastric vessels. It transmits the spermatic cord in the male
and the round ligament in the female. From its circumference a thin funnel-
shaped membrane, the infundibuliform or internal spermatic fascia, is continued
round the cord and testis. enclosing them in a distinct pouch.
OF THE ABDOMEN
449
EXTERNAL OBLIQUE
(reflected inward;
POSTERIOR WALL OF
INGUINAL CANAL
INTERNAL ORIGIN
OF CRENASTER
FIG. 298. — The right inguinal canal in the male, second layer, viewed from in front,
is shown in Fig. 289.) (Spalteholz.)
(The first layer
INTERNAL OBLIQUE
(reflected inward)
EXTERNAL OBLIQUE
(reflected inward)
OBLIQUE
(reflected
downward)
FIG. 299. — The right inguinal canal in the male, third layer, viewed from in front.
29
(Spalteholz.>
450 THE MUSCLES AND FASCIA
When the sac of an oblique inguinal hernia passes through the internal or deep abdominal
ring, the infundibuliform process of the transversalis fascia forms one of its coverings.
The Inguinal or Spermatic Canal (canalis inguinalis} (Figs. 298 and 299) . — The
inguinal or spermatic canal contains the spermatic cord (funiculus spermaticus) in
the male and the round ligament (ligamentum teres uteri] in the female. It is an
oblique canal about an inch and a half in length, directed downward and inward,
and placed parallel to and a little above Poupart's ligament. It commences above
at the internal or deep abdominal ring, which is the point where the cord enters
the spermatic canal, and terminates below at the external ring. It is bounded
in front by the integument and superficial fascia, by the aponeurosis of the
External oblique throughout its whole length, and by the Internal oblique for
its outer third; behind, by the triangular fascia, the conjoined tendon of the
Internal oblique and Transversalis, transversalis fascia, and the subperitoneal
fat and peritoneum ; above, by the arched fibres of the Internal oblique and Trans-
versalis; below, by Gimbernat's ligament, and by the union of the fascia trans-
versalis with Poupart's ligament. The median aspect of the floor of the canal is
strengthened by dense fibres which are attached to the pubis and to the Rectus
muscle. These fibres constitute the falx inguinalis, or ligament of Henle. The deep
epigastric artery passes upward and inward behind the canal lying close to the
inner side of the internal abdominal ring (Fig. 291). The interval between this
artery and the outer edge of the Rectus is named Hesse Ibach's triangle, the base of
which is formed by Poupart's ligament.
That form of protrusion in which the intestine follows the course of the spermatic cord along
the spermatic canal is called oblique inguinal hernia.
The Deep Crural Arch. — Curving over the vessels, just at the point where they
become femoral, on the abdominal side of Poupart's ligament and loosely con-
nected with it, is a thickened band of fibres called the deep crural arch. It is
apparently a thickening of the fascia transversalis, joining externally to the centre
of Poupart's ligament, and arching across the front of the crural sheath to be
inserted by a broad attachment into the spine of the os pubis and ilio-pectineal
line, behind the conjoined tendon. In some subjects this structure is not very
prominently marked, and not infrequently it is altogether wanting.
Cooper's Ligament or the Reflected Tendon of Cooper (Fig. 297) is a small reflection
from the tendon of the Transversalis which passes downward and outward behind
Gimbernat's ligament.
The External Abdominal Ring (annulus abdominalis subcutaneus). — See p. 437.
Surface Form. — The only two muscles of this group which have any considerable influ-
ence on surface form are the External oblique and Rectus muscles of the abdomen. With
regard to the External oblique, the upper digitations of its origin from the ribs are well marked,
intermingled with the serrations of the Serratus magnus; the lower digitations are not visible,
being covered by the thick border of the Latissimus dorsi. Its attachment to the crest of the
ilium, in conjunction with the Internal oblique, forms a thick oblique roll, which determines the
iliac furrow. Sometimes on the front of the lateral region of the abdomen an undulating out-
line marks the spot where the muscular fibres terminate and the aponeurosis commences. The
outer border of the Rectus is defined by the linea semilunaris, which may be exactly defined by
putting the muscle into action. It corresponds with a curved line, with its convexity outward,
drawn from the end of the cartilage of the ninth rib to the spine of the os pubis, so that the
centre of the line, at or near the umbilicus, is three inches from the median line. The inner
border of the Rectus corresponds to the linea alba, marked on the surface of the body by a
groove, the abdominal furrow, which extends from the infrasternal fossa to, or to a little below,
the umbilicus, where it gradually becomes lost. The surface of the Rectus presents three trans-
verse furrows, the linese transversae. The upper two of these, one opposite or a little below the
tip of the ensiform cartilage, and another, midway between this point and the umbilicus, are
usually well marked; the third, opposite the umbilicus, is not so distinct. The umbilicus, situ-
ated in the linea alba, varies very much in position as regards its level. It is always situated
above a zone drawn round the body opposite the highest point of the crest of the ilium, gen-
erally being about three-quarters of an inch to an inch above this line. It usually corresponds,
therefore, to the fibro-cartilage between the third and fourth lumbar vertebrae.
OF THE 1SCHIO- RECTAL REGION 451
2. The Deep Muscles of the Abdomen.
Psoas magnus. Iliacus.
Psoas parvus. Quadratus lumborum.
The Psoas magnus, the Psoas parvus, and the Iliacus muscles, with the fascia
covering them, will be described with the Muscles of the Lower Extremity.
The Fascia Covering the Quadratus Lumborum (Fig. 294).— This is the most
anterior of the three layers of the lumbar fascia. It is a thin layer of fascia, which,
passing over the anterior surface of the Quadratus lumborum, is attached, inter-
nally, to the bases of the transverse processes of the lumbar vertebrae; below, to
the ilio-lumbar ligament; and above, to the apex and lower border of the last rib.
The portion of this fascia which extends from the transverse process of the
first lumbar vertebra to the apex and lower border of the last rib constitutes the
ligamentum arcuatum externum.
The Quadratus Lumborum (Fig. 282) is situated in the lumbar region. It is
irregularly quadrilateral in shape, and broader below than above. It arises by
aponeurotic fibres from the ilio-lumbar ligament and the adjacent portion of the
crest of the ilium for about two inches, and is inserted into the lower border of
the last rib for about half its length, and by four small tendons, into the apices
of the transverse processes of the four upper lumbar vertebrae. Occasionally a
second portion of this muscle is found situated in front of the preceding. This
arises from the upper borders of the transverse processes of three or four of the
lower lumbar vertebras, and is inserted into the lower margin of the last rib. The
Quadratus lumborum is contained in a sheath formed by the anterior and middle
lamellae of the lumbar fasciae.
Relations. — Its anterior surface (or rather the fascia which covers its anterior
surface) is in relation with the colon, the kidney, the Psoas muscle, and the
Diaphragm. Between the fascia and the muscle are the last thoracic, ilio-hypogas-
tric, and ilio-inguinal nerves. Its posterior surface is in relation with the middle
lamella of the lumbar fascia, which separates it from the Erector spinae. The
Quadratus lumborum extends, however, beyond the outer border of the Erector
spinae.
Nerve-supply. — The anterior branches of the last thoracic and first lumbar
nerves ; sometimes also a branch from the second lumbar nerve.
Actions. — The Quadratus lumborum draws down the last rib. It acts as a
muscle of inspiration by helping to fix the origin of the Diaphragm. If the thorax
and spine are fixed, it may act upon the pelvis, raising it toward its own side
when only one muscle is put in action ; and when both muscles act together, either
from below or above, they flex the trunk.
IV. MUSCLES OF THE PELVIC OUTLET.
The muscles of this region are situated at the pelvic outlet in the ischio-rectal
region and the perinaeum. They include^ the following:
1. Muscles of the ischio-rectal region.
2. Muscles of the perinaeum in the male.
3. Muscles of the perinaeum in the female.
1. The Muscles of the Ischio-rectal Region.
Corrugator cutis ani. Internal sphincter ani.
External sphincter ani. Levator ani.
Coccygeus.
The Corrugator Cutis Ani. — Around the anus is a thin stratum of involuntary
muscular fibre, which radiates from the orifice. Internally, the fibres fade off
452
THE MUSCLES AND FASCIA
into the submucous tissue, while externally they blend with the true skin. By
its contraction it raises the skin into ridges around the margin of the anus.
The External Sphincter Ani (m. sphincter ani externus) (Figs. 300, 305, 306, and
307) is a thin, flat plane of muscular fibres, elliptical in shape and intimately adher-
FR/ENUM OF
PREPUCE
EXTERNAL
ABDOMINAL RING
FASCIA OF
PENIS
INFERIOR
RAMUS OF
ISCHIUM
rUBEROSITY
OF ISCHIUM
:; INFERIOR
|i LAYER OF
:N TRIANGULAR
Sl| LIGAMENT
sJM" TRANSVERSUS
^||: PERINEI
^| SUPERFICIALIS
OBTURATOR
'FASCIA
ISCHIO-RECTAU
'FOSSA
ANO-COCCYGEAL LIGAMENT
FIG. 300. — The muscles of the male perinseum, viewed from below. (Spalteholz.)
ent to the integument surrounding the margin of the anus. It measures about
three or four inches in length from its anterior to its posterior extremity, being
about an inch in breadth opposite the anus. It arises from the tip and back of
the coccyx by a narrow tendinous band, and from the superficial fascia in front
OF THE I8CHIO- RECTAL REGION
453
of that bone; and is inserted into the raphe of the Accelerator urinae muscle and
into the central tendinous point of the perinaeum, joining with the two Superficial
transverse perineal, the I^evator ani, and the Accelerator urinae muscles. Many
of the fibres are continuous with the Accelerator urinje in the male and with the
Sphincter vaginae in the female. Often some of the fibres are continuous with the
Transverse perineal muscles. It is continuous above with the Levator ani. Like
other sphincter muscles, it consists of two planes of muscular fibre, which sur-
round the margin of the anus and join in a commissure in front and behind,
some fibres crossing from side to side in front and behind the anus.
Nerve-supply. — A branch from the anterior division of the fourth sacral and
the inferior hsemorrhoidal branch of the internal pudic.
Actions. — The action of this muscle is peculiar: 1. It is, like other sphincter
muscles, always in a state of tonic contraction, and having no antagonistic muscle,
it keeps the anal orifice closed. 2. It can be put into a condition of greater con-
PECTINEUS
ADDUCTOR
UONGUS.
GRACILIS.
Epididymis.
Ampulla.
Ampulla of vasa
deferens.
Testicle.
Ascending ramus of
ISCHIUM.
Internal pudic
vessels and nerve
OBTURATOR INTERNUS.
FIG. 301. --Side view of pelvis, showing Levator ani. (From a preparation in the Museum of the Royal
College of Surgeons.)
.
traction under the influence of the will, so as to occlude more firmly the anal
aperture in expiratory efforts unconnected with defecation. 3. Taking its fixed
point at the coccyx, it helps to fix the central point of the perinseum, so that the
Accelerator urinse may act from this fixed point.
The Internal Sphincter Ani (TO. sphincter ani internus) is a muscular ring
which surrounds the lower extremity of the rectum for about an inch, its inferior
border being contiguous to, but quite separate from, the External sphincter.
This muscle is about two lines in thickness, and is formed by an aggregation
of the involuntary circular fibres of the intestine. It is paler in color and less
coarse in texture than the External sphincter.
Actions. — Its action is entirely involuntary. It helps the External sphincter
to occlude the anal aperture.
The Levator Ani (Figs. 301, 302, 303, and 304) is a broad, thin muscle,
situated on each side of the pelvis. It is attached to the inner surface of the
454
THE MUSCLES AND FASCIA
sides of the true pelvis, and, descending, unites with its fellow of the opposite side
to form the floor of the pelvic cavity. It supports the viscera in this cavity and
surrounds the various structures which pass through it. It is usually possible to
detect an interval between the fibres rising from the pubis and those rising from
the pelvic fascia, and this interval marks the fact that the muscle described as one
is really two. The pubic fibres constitute the Pubococcygeus muscle and the
other fibres the Iliococcygeus muscle.1
The Pubococcygeus muscle takes origin from the posterior aspect of the ramus
of the pubis and from the most anterior portion of the tendinous arch of the
Levator ani muscle. The fibres of origin from the pubis surround anteriorly the
origin of the Internal obturator muscle. The muscle is a band, about one inch in
width, thickest at its outer border, where it overlaps the Iliococcygeus. It passes
backward, downward, and inward, "near the prostate in the male, the urethra
and vagina in the female,"2 and near to the rectum. Most of the fibres pass back
ANTERIOR SACRO-
COCCYGEAL LIGAMENT
GREAT SACRO-
SCIATIC LIGAMENT
OBTURATOR
CANAL
SUPERIOR LAYER
OF TRIANGULAR
LIGAMENT
FIG. 302. — The Levator ani of the male, viewed from above. (Spalteholz.)
of the rectum, where they meet and join with the corresponding fibres of the
opposite side. These united fibres form a thick, tendinous aponeurosis. "This
is continued upward in front of the coccyx for some distance, and finally divides
into two lateral portions, which have been named the ligamenta sacro-coccygea
anterior. They are situated on either side of the middle sacral artery, and are
finally inserted into the last one or two pieces of the sacrum and the first piece
of the coccyx."3 A few of the fibres of the Pubococcygeus muscle pass to the
1 Peter Thompson. The Myology of the Pelvic Floor.
2 Spalteholz's Atlas. Translated and edited by Barker.
8 Peter Thompson. The Myology of the Pelvic Floor.
OF THE ISCHIO- RECTAL REGION
455
central tendon of the perinseum, come in contact with but do not terminate in the
rectal wall, descend in front of and close to the anterior rectal wall, and terminate
in the anterior portion of the sphincter ani and in the skin of the anus (Peter
Thompson).
Luschka and others believe that these anterior fibres descend among the longi-
tudinal fibres of the rectum. It is certain that the most anterior fibres of the
•""•-"•'V inaniiufliiiiiIIL
COWPER'S SUPERFICIAL TRANS-
GLANDS VERSUS PEP.INEI
FIG. 303. — The right Levator ani in the male, viewed from the left. (Spalteholz.)
Pubococcygeus muscle pass to the central point of the perineum. They pass
"backward and downward on the side of the prostate, and in some cases on the
side of the urethra immediately it emerges from the prostate."1 These anterior
fibres in the female descend upon the side of the vagina. The anterior fibres
are the preanal fibres of the Levator ani. They constitute what Santorini named
1 Peter Thompson. The Myology of the Pelvic Floor.
456
THE MUSCLES AND FASCIAE
the levator prostatse, because he regarded them as constituting a distinct
muscle, which surrounds the prostate as a sling. Krause calls these fibres
the levator urethrae; Testut, the fibres pre"-rectales, and Prout, the Recto-urethralis
muscle.
The Iliococcygeus muscle arises from the tendinous arch of the Levator ani muscle
(arcus tendineus m. levatoris ani). This arch is concave upward. The anterior
end of the arch begins on the posterior surface of the superior ramus of the
pubis. "The posterior end can be followed as far as the linea arcuata of the
ilium, between these two points it descends for a variable distance, but always
leaves the canalis obturatorius free."1 The fibres, coursing internally and down-
ward, pass below the posterior portion of the Pubococcygeus. The anterior
fibres join the fibres of the other side, between the anus and the tip of the coccyx
in a median raphe.
The posterior fibres are inserted into the sides of the last two pieces and into
the tip of the coccyx. Peter Thompson points out that the Iliococcygeus muscle
is liable to variations. It is strongly developed in but few, is usually thin, the
muscular bundles being separated by membranous intervals; it may be replaced
by fibrous tissue and may even be absent.2
ANTERIOR-
SUPERIOR
SPINES
POU
LIGAMENT
OBTURATOR
ARTERY
"^f — WHITE LINE
EATER
SACRO-SCIATIC
LIGAMENT
FASCIA OF
LEVATOR ANI
MUSCLE
TUBEHOSITY
OF ISCHIUM
FIG. 304. — Pelvic fascia (semi-diagrammatic).
Relations of the Levator Ani. — By its inner or pelvic surface, with the recto-
vesical fascia, which separates it from the viscera of the pelvis and from the
peritoneum. By its outer or perineal surface, it forms the inner boundary
of the ischio-rectal fossa, and is covered by a thin layer of fascia, the ischio-
rectal or anal fascia, given off from the obturator fascia. Its posterior border is
free and separated from the Coccygeus muscle by a cellular interspace. Its
anterior border is separated from the muscle of the opposite side by a triangular
space, through which the urethra, and in the female the vagina, passes from the
pelvis.
Nerve-supply. — A branch from the anterior division of the fourth sacral nerve
and a branch from the pudic nerve, which is sometimes derived from the perineal
and sometimes from the inferior hemorrhoidal division.
Actions. — The entire Levator ani muscle enters into the formation of the
diaphragm of the pelvis and aids in supporting the rectum, vagina, and bladder.
1 Spalteholz's Atlas. Translated and edited by Barker.
2 Myology of Muscles.
OF THE PERINEUM IN THE MALE 457
The two parts of the muscle have different functions. The Iliococcygei have
no other function than that of supporting the viscera. In early life they flex the
vertebrae of the coccyx on one another and flex the coccyx on the sacrum, but do
not act directly at any age on the rectum or pelvic viscera (Peter Thompson).
The Pubococcygei, especially in the female, have most important functions.
They are the most influential supports of the pelvic floor and restore the pelvic
floor to its proper position after the depression induced by parturition, defecation,
and efforts at urination.1 Normally, they pull the perinaeum upward after the
descending head has pulled it down. In some cases the contraction of the muscles
actually obstructs the descent of the head (Peter Thompson). The muscles are
strongly developed in females, and, acting with the Sphincter vaginae, they aid
in contracting the vaginal canal. The muscles constrict the rectum and also lift
the rectum with the pelvic floor. During defecation the position of the rectal
contents is maintained by intra-abdominal pressure, the muscles lift the perinseum
over the fecal matter (Goffe). The Levator ani is also a muscle of forced
expiration.
The Coccygeus is a flat, triangular muscle situated behind and parallel with
the preceding. It is a triangular plane of muscular and tendinous fibres, arising,
by its apex, from the spine of the ischium, the obturator fascia, the edge of the
great sacro-sciatic notch, and from the lesser sacro-sciatic ligament, and inserted,
by its base, into the side of the lower two vertebras of the sacrum and the upper
two vertebrae of the coccyx. It assists the Levator ani and Pyriformis in closing
in the back part of the outlet of the pelvis.
Relations. — By its inner or pelvic surface, with the rectum. By its external
surface, with the lesser sacro-sciatic ligament. The lower border is in relation
with the posterior border of the Levator ani, but separated from it by a
cellular interval: its upper border is in relation with the lower border of the
Pyriformis, but separated from it by the sciatic and internal pudic vessels and
nerve.
Nerve-supply. — A branch from the fourth and fifth sacral nerves.
Action. — The Coccygei muscles raise and support the coccyx, after it has been
pressed backward during defecation or parturition.
2. The Muscles and Fasciae of the Perinaeum in the Male
(Figs. 300, 305, 306, 307).
Transversus perinei superficialis. Erector penis.
Accelerator urinse. Compressor urethrae.
Superficial Fascia (fascia superficialis perinei). — The superficial fascia of the
perinaeum consists of two layers, superficial and deep, as in other regions of the
body. The superficial fascia over the posterior portion of the perinaeum is
arranged in fatty layers which fill the ischio-rectal fossa on each side of the
rectum and anus. The superficial fascia over the anterior portion of the peri-
naeum (urethra! region) requires fuller consideration.
The Superficial Layer is thick, loose, areolar in texture, and, except toward the
scrotum, contains much adipose tissue in its meshes, the amount of which varies
in different subjects. In front, it is continuous with the dartos of the scrotum;
behind, it is continuous with the subcutaneous areolar tissue surrounding the
anus; and, on either side, with the same fascia on the inner side of the thighs. In
the middle line it is adherent to the skin of the raphe* and to the deep layer of
1 Peter Thompson. The Myology of the Pelvic Floor.
458
THE MUSCLES AND FASCIA
the superficial fascia. This layer should be carefully removed after it has been
examined, when the deep layer will be exposed.
The Deep Layer of Superficial Fascia or the Fascia of Golles is thin, aponeurotic
in structure, and of considerable strength, serving to bind down the muscles of the
root of the penis. It is continuous, in front, with the deep fascia of the penis,
and the dartos of the scrotum, the fascia of the spermatic cord, and Scarpa's
fascia upon the anterior portion of the abdomen; on either side it is firmly
attached to the margins of the rami of the os pubis and ischium, external to
the crus penis, and as far back as the tuberosity of the ischium; posteriorly,
it curves down behind the Superficial transverse perineal muscles (reflected
portion of fascia) to join the lower margin of the* triangular ligament, which
structure is a prolongation of the deep layer of the superficial fascia. The
deep layer is attached to the superficial layer in the median line and to the
FIG. 305. — The perinseum. The integument and superficial layer of superficial fascia reflected.
median septum of the Accelerator urinae muscle. At the central tendon of the
perinseum the reflected portion of the fascia becomes blended with the inser-
tions of the External anal sphincter, the two Superficial transverse perineal
muscles, and the Accelerator urinse. This fascia not only covers the muscles
in this region, but sends upward a vertical septum from its deep surface, which
separates the back part of the subjacent space into two, the septum being
incomplete in front.
The Central Tendinous Point of the Perinaeum. — This is a fibrous point in the
middle line of the perinseum, between the urethra and the rectum, being about
half an inch in front of the anus. At this point four muscles converge and are
attached — viz., the External sphincter ani, the Accelerator urinse, and the two
Superficial transverse perineal ; so that by the contraction of these muscles, which
extend in opposite directions, it serves as a fixed point of support.
OF THE PERINEUM IN THE MALE
459
The Transversus Perinei Superficialis is a narrow muscular slip, which passes
more or less transversely across the back part of the perineal space. It arises
by a small tendon from the inner and forepart of the tuberosity of the ischium,
and, passing inward, is inserted into the central tendinous point of the perineum,
joining in this situation with the muscle of the opposite side, the External
sphincter ani behind, and the Accelerator urinse in front. The base of the tri-
angular ligament lies just beneath this muscle.
Nerve-supply. — The perineal branch of the internal pudic.
Actions. — By their contraction they serve to fix the central tendinous point of
the perinfeum.
The Accelerator Urinae, called also the Ejaculator seminis and the Ejaculator
urinae (m. bulbocavernosus) , is placed in the middle line of the perineeum, imme-
diately in front of the anus. It consists of two symmetrical halves, united
along the median line by a tendinous raphe". It arises from the central tendon
Transrersus perinei
superficialis.
GREAT SACRO-
SCIATIC LIGAMENT
Superficial perineal artery.
Superficial perineal nerve.
Internal pudic nerve.
Internal pudic artery.
FIG. 306. — The superficial muscles and vessels of the perinseum.
of the perinseum, and from the median raphe" in front. From this point its fibres
diverge like the plumes of a pen; the most posterior form a thin layer, which is
lost on the anterior surface of the triangular ligament; the middle fibres encircle
the bulb and adjacent parts of the corpus spongiosum, and join with the fibres
of the opposite side, on the upper part of the corpus spongiosum, in a strong
aponeurosis; the anterior fibres, the longest and most distinct, spread out over
the sides of the corpus cavernosum, to be inserted partly into that body, anterior
to the Erector penis, occasionally extending to the os pubis; partly terminating
in a tendinous expansion, which covers the dorsal vessels of the penis. The latter
fibres are best seen by dividing the muscle longitudinally, and dissecting it out-
ward from the surface of the urethra. Many fibres of the External sphincter
ani and of the Superficial transverse perineal muscles pass into this muscle.
Action. — This muscle serves to empty the canal of the urethra, after the
bladder has expelled its contents ; during the greater part of the act of micturition
460
THE MUSCLES AND FASCIAE
its fibres are relaxed, and it only comes into action at the end of the process.
The middle fibres are supposed, by Krause, to assist in the erection of the corpus
spongiosum, by compressing the erectile tissue of the bulb. The anterior fibres,
on each side, which are known as Houston's muscles, according to Tyrrel, also
contribute to the erection of the penis, as they are inserted into, and continuous
with, the fascia of the penis, compressing the dorsal vein during the contraction
of the muscle.
The Erector Penis (TO. ischiocavernosus) covers part of the crus penis. It is an
elongated muscle, broader in the middle than at either extremity, and situated on
either side of the lateral boundary of the perinaeum. It arises by tendinous and
fleshy fibres from the inner surface of the tuberosity of the ischium, behind the
crus penis, from the surface of the crus, and from the adjacent portion of the
ramus of the ischium. From these points fleshy fibres succeed, which end
in an aponeurosis which is inserted into the sides and under surface of the
crus penis.
Nerve-supply. — The perineal branch of the internal pudic.
Anterior layer of
deep perineal fascia removed,
showing
COMPRESSOR URETHRJE.
rnternal pudic artery.
•Artery of the bulb.
Cowper's gland.
FIG. 307. — Triangular ligament or deep perineal fascia. On the left side the anterior layer has been removed.
Actions. — It compresses the crus penis and retards the return of the blood
through the veins, and thus serves to maintain the organ erect.
Between the muscles just examined a triangular space exists, bounded inter-
nally by the Accelerator urinse, externally by the Erector penis, and behind by
the Trans versus perinei superficialis. The floor of this space is formed by the
triangular ligament of the urethra (deep perineal fascia), and running from behind
forward in it are the superficial perineal vessels and nerves, the long pudendal
nerve, and the transverse perineal artery coursing along the posterior boundary
of the space on the Trans versus perinei superficialis.
The Triangular Ligament or the Deep Perineal Fascia (trigonum or diaphragma
urogenitale) (Figs. 304, 308, and 309) is stretched almost horizontally across the
pubic arch, so as to close in the front part of the outlet of the pelvis. It con-
OF THE PERINEUM IN THE MALE
461
sists of two dense musculo-membranous laminae, which are united along their
posterior borders, but are separated in front by intervening structures. The
superficial of these two layers, the superficial, anterior, or inferior layer of the
triangular ligament (fascia trigoni urogenitalis inferior), is triangular in shape
and about an inch and a half in depth. Its apex is directed forward, and is
separated from the subpubic ligament by an oval opening for the transmission
of the dorsal vein of the penis. The apex of the triangular ligament is called the
PERITONEUM
PRO-STATIC
FASCIA
DEEP LAYER OF
SUPERFICIAL FASCIA
DEEP LAYER
OF TRIANGULAR
LIGAMENT
COMPRESSOR
URETHR«
MUSCLE
SUPERFICIAL LAYER OF
TRIANGULAR LIGAMENT
FIG. 308. — The aponeurosis of the perinseum. (Denonvilliers.)
transverse perineal or transverse pelvic ligament (ligamentum transversum pelvis).
The lateral margins of the inferior layer of the triangular ligament are attached
on each side to the rami of the ischium and os pubis, above the crura penis.
The fusion of the two leaves posteriorly takes place beneath the Superficial
transverse perineal muscles. The region of fusion of the two leaflets posteriorly
is called the base. The base is directed toward the rectum, and connected to
URETHRA-j-
DORSAL VEIN
OF PENIS
DORSAL NERVE
OF PENIS
DORSAL ARTERY
OF PENIS
ARTERY TO
BULB
COMPRESSOR
URETHR/E
CORPUS
SPONGIOSUM
CORPUS
CAVERNOSUM
TRIANGULAR
LIGAMENT
upper margin)
•^ ^ii.
FIG. 309. — The superficial layer of the triangular ligament. The Compressor urethra; muscle lies behind the
superficial layer of the triangular ligament and is shown in the figure for convenience. (Poirier and Charpy.)
the central tendinous point of the perinaeum. It is continuous with the deep
layer of the superficial fascia behind the Superficial transverse perineal muscles,
and with a thin fascia which covers the cutaneous surface of the Levator ani
muscle, the anal or ischio-rectal fascia.
This layer of the triangular ligament is perforated, about an inch below the
symphysis pubis, by the urethra, the aperture for which is circular in form and
462 THE MUSCLES AND FASCIAE
about three or four lines in diameter; by the arteries to the bulb and the ducts of
Cowper's glands close to the urethral orifice; by the arteries to the corpora caver-
.nosa — one on each side, close to the pubic arch and about half-way along the
attached margin of the ligament; by the dorsal arteries and nerves of the penis near
the apex of the ligament. Its base is also perforated by the superficial perineal
vessels and nerves, while between its apex and the subpubic ligament the dorsal
nerve of the penis and the dorsal vein of the penis passes upward into the
pelvis.
If this superficial or inferior layer of the triangular ligament is detached on
either side, the following structures will be seen between it and the deeper
layer: the dorsal vein of the penis; the membranous portion of the urethra,
and the Compressor urethra? muscle; Cowper's glands and their ducts; the
pudic vessels and dorsal nerve of the penis; the artery and nerve of the bulb,
and a plexus of veins. The two layers join the urethral wall and vagina
median ward.
The deep, posterior, or superior layer (fascia trigoni urogenitalis superior) of the
triangular ligament is derived from the obturator fascia and stretches across
the pubic arch. If the obturator fascia is traced inward after covering the
Obturator internus muscle, it will be found to be attached by some of its
deeper or anterior fibres to the inner margin of the ischio-pubic ramus, while its
superficial or posterior fibres pass over this attachment to become the superior
layer of the triangular ligament. Behind, this layer of the fascia is continuous
with the inferior layer and with the fascia of Colles, and in front it is separated
from the apex of the prostate gland through the intervention of a prolongation of
the recto-vesical fascia. It is pierced by the urethra, or rather consists of two
halves which are separated in the middle line by the urethra passing between
them.
The Compressor or Constrictor Urethra (m. constrictor urethrae) in the male
surrounds the whole length of the membranous portion of the urethra, and is
contained between the two layers of the triangular ligament. It arises, by apon-
eurotic fibres, from the junction of the rami of the os pubis and ischium, to the
extent of half or three-quarters of an inch: the point where the crura penis joins
the transverse ligament of the perineum and the layers of the triangular liga-
ment; each segment of the muscle passes inward, and divides into two fasciculi,
which surround the membranous urethra and unite, at the upper and lower
surfaces of this tube, with the muscle of the opposite side by means of a tendinous
raphe. The Compressor urethrae is continuous posteriorly with the m. prostaticus
and is continuous anteriorly with the circular fibres of the cavernous portion of
the urethra. This muscle is frequently in two portions, an anterior and a
posterior, separated by a distinct interval. In such cases the posterior fibres are
called the transversus perinei profundus, and the anterior fibres are called the
sphincter urethrae membranaceae.
Nerve-supply. — The perineal branch of the internal pudic.
Actions. — The muscles of both sides act together as a sphincter, compressing
the membranous portion of the urethra. During the transmission of fluids they,
like the Acceleratores urinse, are relaxed, and come into action only at the end of
the process, to eject the last drops of the fluid.
3. The Muscles of the Perinseum in the Female (Fig. 310).
Transversus perinei superficialis. Erector clitoridis.
Sphincter vaginae. Compressor urethras.
The Transversus Perinei Superficialis in the female is a narrow muscular slip,
which passes more or less transversely across the back part of the perineal space.
OF THE PERINEUM IN THE FEMALE
463
It arises by a small tendon from the inner and forepart of the tuberosity of the
ischium, and, passing inward, is inserted into the central point of the perinseum,
joining in this situation with the muscle of the opposite side, the External sphinc-
ter ani behind, and the Sphincter vaginae in front.
Nerve-supply. — The perineal branch of the internal pudic.
Actions. — By their contraction they serve to fix the central tendinous point of
the perinseum.
The Sphincter Vaginae (m. 'bulbocavernosus) surrounds the orifice of the
vagina, and is analogous to the Accelerator urinse in the male. It is attached
posteriorly to the central tendinous point of the perinseum, where it blends with
FIG. 310. — Muscles of the female perinaeum.
the External sphincter ani. Its fibres pass forward on each side of the vagina, to
be inserted into the corpora cavernosa of the clitoris, a fasciculus crossing over
the body of the organ so as to compress the dorsal vein.
Nerve-supply. — The perineal branch of the internal pudic.
Actions. — It diminishes the orifice of the vagina. The anterior fibres contribute
to the erection of the clitoris, as they are inserted into and are continuous with the
fascia of the clitoris; compressing the dorsal vein during the contraction of the
muscle.
The Erector Glitoridis (m. ischiocavernosus) resembles the Erector penis in the
male, but is smaller than it. It covers the unattached part of the crus clitoridis.
It is an elongated muscle, broader at the middle than at either extremity, and
situated on either side of the lateral boundary of the perinseum. It arises by
tendinous and fleshy fibres from the inner surface of the tuberosity of the ischium,
behind the crus clitoridis from the surface of the crus, and from the adjacent
portion of the ramus of the ischium. From these points fleshy fibres succeed,
464
THE MUSCLES AND FASCIA
which end in an aponeurosis, which is inserted into the sides and under surface
of the crus clitoridis.
Nerve-supply. — The perineal branch of the internal pudic.
Actions. — It compresses the crus clitoridis and retards the return of blood
through the veins, and thus serves to maintain the organ erect.
The Triangular Ligament (trigonum urogenitale) in the female is not so strong
as in the male. It is divided in the middle line by the aperture of the vagina,
with the external coat of which it becomes blended, and in front of this is
perforated by the urethra. Its posterior border is continuous, as in the male,
with the deep layer of the superficial fascia around the Transversus perinei
muscle.
Like the triangular ligament in the male, it consists of two layers, between
which are to be found the following structures: the dorsal vein of the clitoris,
a portion of the urethra and the Compressor urethrse muscle, the glands of Bar-
tholin and their ducts; the pudic vessels and the dorsal nerve of the clitoris; the
arteries of the bulbi vestibuli, and a plexus of veins.
The Compressor Urethrae (m. constrictor urethrae) arises on each side from the
margin of the descending ramus of the os pubis. The fibres, passing inward,
divide into two sets: those of the forepart of the muscle are directed across the
subpubic arch in front of the urethra to blend with the muscular fibres of the
opposite side; while those of the hinder and larger part pass inward to blend with
the wall of the vagina behind the urethra.
Nerve-supply. — The perineal branch of the internal pudic.
MUSCLES AND FASCIAE OF THE UPPER EXTREMITY.
The 'muscles of the Upper Extremity are divisible into groups, corresponding
with the different regions of the limb.
I. OF THE THORACIC REGION.
1. Anterior Thoracic Region.
Pectoralis major. Pectoralis minor.
Subclavius.
2. Lateral Thoracic Region.
Serratus magnus.
II. OF THE SHOULDER AND ARM.
3. Acromial Region.
Deltoid.
4. Anterior Scapular Region.
Subscapularis.
5. Posterior Scapular Region.
Supraspinatus. Teres minor.
Infraspinatus. Teres major.
6. Anterior Humeral Region.
Coraco-brachialis. Biceps.
Brachialis anticus.
7. Posterior Humeral Region.
Triceps. Subanconeus.
III. OF THE FOREARM.
8. Anterior Radio-ulnar Region.
Pronator radii teres.
Flexor carpi radialis.
Palmaris longus.
Flexor carpi ulnaris.
[Flexor sublimis digitorum.
gi £ f Flexor profundus digitorum.
Q £3* | Flexor longus pollicis.
" [ Pronator quadratus.
9. Radial Region.
Supinator longus.
Extensor carpi radialis longior.
Extensor carpi radialis brevior.
|J
§%3
c/3
ANTERIOR THORACIC REGION 465
10. Posterior Radio-Ulnar Region. Flexor brevis pollicis.
Extensor communis digitorum. Adductor obliquus pollicis.
Extensor minimi digiti. Adductor transversus pollicis.
Extensor carpi ulnaris.
Anconeus. 12. Ulnar Region.
Supinator brevis. Palmaris brevis.
Extensor ossis metacarpi polhci. Abductor minimi digiti.
Extensor brevis polhcis. Flexor breyis minimi digiti
Extensor longus pollicis. Flexor ossig metacarpi minimi digiti
Extensor mdi (Opponens minimi digiti).
IV. OF THE HAND.
11. Radial Region. 13' Middle P-almar Re^n'
Abductor pollicis. Lumbricales.
Flexor ossis metacarpi pollicis Interossei palmares.
(Opponens pollicis). Interossei dorsales.
Dissection of Pectoral Region and Axilla (Fig. 311).— The arm being drawn away from
the side nearly at right angles with the trunk and rotated outward, make a vertical incision
through the integument in the median line of the chest, from the upper to the lower part of the
sternum; a second incision along the lower border of the Pectoral muscle, from the ensiform
cartilage to the inner side of the axilla; a third, from the sternum along the clavicle, as far as its
centre; and a fourth, from the middle of the clavicle obliquely downward, along the interspace
between the Pectoral and Deltoid muscles, as low as the fold of the armpit. The flap of integu-
ment is then to be dissected off in the direction indicated in the figure, but not entirely removed,
as it should be replaced on completing the dissection. If a transverse incision is now made
from the lower end of the sternum to the side of the chest, as far as the posterior fold of the
armpit, and the integument reflected outward, the axillary space will be more completely exposed.
I. THE MUSCLES AND FASCIAE OF THE THORACIC REGION.
1. The Anterior Thoracic Region.
Pectoralis major. Pectoralis minor.
Subclavius.
Superficial Fascia. — The superficial fascia of. the thoracic region is a loose
cellulo-fibrous layer enclosing masses of fat in its spaces. It is continuous with
the superficial fascia of the neck and upper extremity above, and of the abdomen
below. Opposite the mamma it divides into two layers, one of which passes in
front, the other behind, that gland ; and from both of these layers numerous septa
pass into its substance, supporting its various lobes : from the anterior layer fibrous
processes pass forward to the integument and nipple. These processes were called
by Sir A. Cooper the suspensory ligaments (ligamenta suspensoria) , from the sup-
port they afford to the gland in this situation.
Deep Fascia. — The deep thoracic fascia is a thin aponeurotic lamina, cover-
ing the surface of the great Pectoral muscle, and sending numerous prolongations
between its fasciculi: it is attached, in the middle line, to the front of the sternum,
and above to the clavicle; externally and below it becomes continuous with the
fascia over the shoulder, axilla, and thorax. It is very thin over the upper part
of the muscle, thicker in the interval between the Pectoralis major and Latissimus
dorsi, where it closes in the axillary space, and is known as the axillary fascia (fascia
axillaris). It passes behind into the fascia of the Latissimus dorsi and Teres
major, in front into the fascia of the deltoid and outward into the brachial
fascia. The fascia of the Latissimus dorsi divides at the outer margin of the
muscle into two layers, one of which passes in front and the other behind it; these
proceed as far as the spinous processes of the thoracic vertebrae, to which they are
30
466
THE MUSCLES AND FASCIAE
attached. As the axillary fascia leaves the lower edge of the Pectoralis major to
pass across the floor of the axilla it sends a layer upward under cover of the
muscle, deep pectoral fascia: this lamina splits to envelop the Pectoralis minor, at
the upper edge of which it becomes continuous with the costo-coracoid membrane,
or the clavi-pectoral fascia. The hollow of the armpit, seen when the arm is
abducted, is mainly produced by the traction of this fascia on the axillary floor,
the axillary fascia (fascia axillaris), and hence it is sometimes named the
suspensory ligament of the axilla. The axillary fascia (Fig. 312) is not a dis-
tinct and complete rigid floor of the axillary space. Like all other fascia?, it
follows muscular planes, and splits to encompass vessels, nerves, and muscles.
In it are numerous perforations. In this fascia is a curved arch which often
contains muscular fibres and which passes from the tendon of the great Pectoral,
3. Dissection of
Shoulder and Arm.
1. Dissection of
Pectoral Region
and Axilla.
2. Bend of Elbow.
4: Forearm.
Palm of Hand.
FIG. 311. — Dissection of the upper extremity.
the Coraco-brachialis or the fascia over the biceps to the tendon of the Latissimus
dorsi. This is called the axillary arch (arcus axillaris}. Langer showed many years
ago that there is an opening in the centre of the dense axillary fascia, the foramen
of Langer. Through this opening axillary glands not unusually protrude. The
axillary arch is the inner margin of the foramen of Langer. At the lower part of
the thoracic region the deep thoracic fascia is well developed, and is continuous
with the fibrous sheath of the Recti muscles.
The Pectoralis Major (Fig. 313) is a broad, thick, triangular muscle, situated
at the upper and forepart of the chest, in front of the axilla. It arises from the
anterior surface of the sternal half of the clavicle; from half the breadth of the
anterior surface of the sternum, as low down as the attachment of the cartilage
of the sixth or seventh rib; this portion of its origin consists of aponeurotic fibres,
which intersect with those of the opposite muscle; it also arises from the carti-
THE ANTERIOR THORACIC REGION
467
lages of all true ribs, with the exception, frequently, of the first or of the seventh,
or both; and from the aponeurosis of the External oblique muscle of the abdo-
men. The fibres from this extensive origin converge toward its insertion, giving
to the muscle a radiated appearance. Those fibres which arise from the clavicle
pass obliquely outward and downward and are usually separated from the rest
by a cellular interval: those from the lower part of the sternum, and the cartilages
of the lower true ribs, pass upward and outward, whilst the middle fibres pass
horizontally. They all terminate in a flat tendon, about two inches broad, which
is inserted into the outer bicipital ridge of the humerus. This tendon consists of
two laminge, placed one in front of the other, and usually blended together below.
The anterior, the thicker, receives the clavicular and upper half of the sternal
portion of the muscle; and its fibres are inserted in the same order as that in
which they arise; that is to say, the outermost fibres of origin from the clavicle are
SUBSCAPULAR
ARTERY AND VEIN
FIG. 312. — The fascia of the right axilla, viewed from below. (Spalteholz.)
inserted at the uppermost part of the tendon; the upper fibres of origin from the
sternum pass down to the lowermost part of this anterior lamina of the tendon
and extend as low as the tendon of the Deltoid and join with it. The posterior
lamina of the tendon receives the attachment of the lower half of the sternal por-
tion and the deeper part of the muscle from the costal cartilages. These deep
fibres, and particularly those from the lower costal cartilages, ascend, the higher,
turning backward successively behind the superficial and upper ones, so that the
tendon appears to be twisted. The posterior lamina reaches higher on the humerus
than does the anterior one, and from it an expansion is given off which covers
the bicipital groove and blends with the capsule of the shoulder-joint. From the
deepest fibres of this lamina at its insertion an expansion is given off which lines
the bicipital groove of the humerus, while from the lower border of the tendon a
third expansion passes downward to the fascia of the arm. Between the poste-
468
THE MUSCLES AND FASCIA
rior surface of the tendon of the great pectoral and the anterior surface of the
long head of the biceps there is usually a bursa (bursa m. pectoralis majoris),
Relations. — By its anterior surface, with the integument, the superficial fascia,
the Platysma, some of the branches of the descending cervical nerves, the mam-
mary gland, and the deep fascia; by its posterior surface: its thoracic portion, with
the sternum, the ribs and costal cartilages, the costo-coracoid membrane, the Sub-
clavius, Pectoralis minor, Serratus magnus, and the Intercostals ; its axillary por-
FIG. 313. — Muscles of the chest and front of the arm. Superficial view.
tion forms the anterior wall of the axillary space, and covers the axillary vessels and
nerves, the Biceps and Coraco-brachialis muscles. Its upper border lies parallel
with the Deltoid, from which it is separated by a slight interspace in which lie the
cephalic vein and humeral branch of the acromial thoracic artery. Its lower border
forms the anterior margin of the axilla, being at first separated from the Latissimus
dorsi by a considerable interval; but both muscles gradually converge toward the
outer part of the space.
TI1K ANTERIOR THORACIC REGION
469
Dissection. — Detach the Pectoralis major by dividing the muscle along its attachment to
the clavicle, and by making a vertical incision through its substance a little external to its line of
attachment to the sternum and costal cartilages. The muscle should then be reflected outward,
and its tendon carefully examined. The Pectoralis minor is now exposed, and immediately
above it, in the interval between its upper border and the clavicle, a strong fascia, the costo-
coracoid membrane.
The Costo-coracoid Membrane or the Clavipectoral Fascia is a strong fascia,
situated under cover of the clavicular portion of the Pectoralis major muscle. It
occupies the interval between the Pectoralis minor and Subclavius muscle, and pro-
tects the axillary vessels and nerves. Traced upward, it splits to enclose the Sub-
clavius muscle, and its two layers are attached to the clavicle, one in front of and
the other behind the muscle; the latter layer fuses with the deep cervical fascia and
FIG. 314. — Muscles of the chest and front of the arm, showing some of the boundaries of the axilla.
with the sheath of the axillary vessels. Internally, it blends with the fascia covering
the first two intercostal spaces, and is attached also to the first rib internal to the
origin of the Subclavius muscle. Externally it is very thick and dense, and is
attached to the coracoid process. The portion extending from its attachment to
the first rib to the coracoid process is often whiter and denser than the rest; this
is sometimes called the costo-coracoid ligament. Below, it is thin, and at the upper
border of the Pectoralis minor it splits into two layers to invest the muscle; from
the lower border of the Pectoralis minor it is continued downward to join the axil-
lary fascia, and outward to join the fascia over the short head of the Biceps. The
costo-coracoid membrane is pierced by the cephalic vein, the acromial thoracic
artery and vein, superior thoracic artery, and anterior thoracic nerves.
470 THE MUSCLES AND FASCIAE
The Pectoralis Minor (Fig. 314) is a thin, flat, triangular muscle, situated at
the upper part of the thorax, beneath the Pectoralis major. It arises by three
tendinous digitations from the upper margin and outer surface of the third, fourth,
and fifth ribs, near their cartilages, and from the aponeurosis covering the Inter-
costal muscles; the fibres pass upward and outward, and converge to form a flat
tendon, which is inserted into the inner border and upper surface of the coracoid
process of the scapula.
Relations. — By its anterior surface, with the Pectoralis major and the thoracic
branches of the acromial thoracic artery. By its posterior surface, with the
ribs, Intercostal muscles, Serratus magnus, the axillary space, and the axillary
vessels and brachial plexus of nerves. Its upper border is separated from the
clavicle by a triangular interval, broad internally, narrow externally, which is
occupied by the costo-coracoid membrane. This space contains the first part of
the axillary vessels and the axillary nerves. Running parallel to the lower border
of the muscle is the long thoracic artery.
The costo-coracoid membrane should now be removed, when the Subclavius muscle will
be seen.
The Subclavius is a small triangular muscle, placed in the interval between the
clavicle and the first rib. It arises by a short, thick tendon from the first rib and
its cartilage at their junction, in front of the rhomboid ligament; the fleshy fibres
proceed obliquely upward and outward, to be inserted into a deep groove on the
under surface of the clavicle. An extension from the aponeurosis of this muscle
lies upon the subclavian vein.
Relations. — By its upper surface, with the clavicle. By its deep surface it is
separated from the first rib by the subclavian vessels and brachial plexus of nerves.
Its anterior surface is separated from the Pectoralis major by the costo-coracoid
membrane, which, with the clavicle, forms an osseo-fibrous sheath in which the
muscle is enclosed.
If the costal attachment of the Pectoralis minor is divided across, and the muscle reflected
outward, the axillary vessels and nerves are brought fully into view, and should be examined.
Nerves. — The Pectoral muscles are supplied by the anterior thoracic nerves;
the Pectoralis major through these nerves receives filaments from all the spinal
nerves entering into the formation of the brachial plexus; the Pectoralis minor
receives its fibres from the eighth cervical and first thoracic nerves. The Sub-
clavius is supplied by a filament from the fifth cervical nerve.
Actions. — If the arm has been raised by the Deltoid, the Pectoralis major will,
conjointly with the Latissimus dorsi and Teres major, depress it to the side of the
chest. If acting alone, it adducts and draws forward the arm, bringing it across
the front of the chest, and at the same time rotates it inward. The Pectoralis minor
depresses the point of the shoulder, drawing the scapula downward and inward
to the thorax, and throwing the inferior angle backward. The Subclavius de-
presses the shoulder, drawing the clavicle downward and forward. When the
arms are fixed, all three muscles act upon the ribs, drawing them upward and
expanding the chest, and thus becoming very important agents in forced inspira-
tion. Asthmatic patients always assume an attitude which fixes the shoulders, so
that all these muscles may be brought into action to assist in dilating the cavity
of the chest.
THE LATERAL THORACIC -REGION 471
2. The Lateral Thoracic Region.
Serratus magnus.
The Serratus Magnus (m. serratus anterior} (Fig. 314) is a thin, irregularly
quadrilateral muscle, situated between the ribs and the scapula at the upper
and lateral part of the chest. It arises by nine digitations or slips from the outer
surface and upper border of the eight upper ribs (the second rib giving origin to
two slips), and from the aponeurosis covering the corresponding intercostal
muscles. From this extensive attachment the fibres pass backward, closely applied
to the chest-wall, and reach the vertebral border of the scapula, and are inserted
into its ventral aspect in the following manner. The upper two' digitations — i. e.,
the one from the first rib and the higher of the two from the second rib — converge
to be inserted into a triangular area on the ventral aspect of the superior angle.
The next two digitations spread out to form a thin triangular sheet, the base of
which is directed backward and is inserted into nearly the whole length of the
ventral aspect of the vertebral border. The lower five digitations converge, as they
pass backward from the ribs, to form a fan-shaped structure, the apex of which
is inserted, partly by muscular and partly by tendinous fibres, into a triangular
impression on the ventral aspect of the inferior angle. The lower four slips inter-
digitate at their origin with the upper five slips of the External oblique muscle
of the abdomen.
Relations. — This muscle is partly covered, in front, by the Pectoral muscles;
behind, by the Subscapularis. The axillary vessels and nerves lie upon its upper
part, while its deep surface rests upon the ribs and intercostal muscles.
Nerve. — The Serratus magnus is supplied by the posterior thoracic nerve,
which is derived from the fifth, sixth, and generally the seventh cervical nerves.
Actions. — The Serratus magnus, as a whole, carries the scapula forward, and at
the same time raises the vertebral border of the bone. It is therefore concerned
in the action of pushing. Its lower and stronger fibres move forward the lower
angle and assist the Trapezius in rotating the bone round an axis through its
centre, and thus assists this muscle in raising the acromion and supporting weights
upon the shoulder. It is also an assistant to the Deltoid in raising the arm, inas-
much as during the action of this latter muscle it fixes the scapula and so steadies
the glenoid cavity on which the head of the humerus rotates. After the Deltoid
has raised the arm to a right angle with the trunk, the Serratus magnus and the
Trapezius, by rotating the scapula, raise the arm into an almost vertical position.
It is possible that when the shoulders are fixed the lower fibres of the Serratus
magnus may assist in raising and everting the ribs; but it is not the important
inspiratory muscle which it was formerly believed to be.
Surgical Anatomy. — When the muscle is paralyzed, the vertebral border, and especially the
lower angle of the scapula, leaves the ribs and stands out prominently on the surface, giving
a peculiar "winged" appearance to the back. The patient is unable to raise the arm, and an
attempt to do so is followed by a further projection of the lower angle of the scapula from the
back of the thorax.
Dissection. — After completing the dissection of the axilla, if the muscles of the back have
been dissected, the upper extremity should be separated from the trunk. Saw through the
clavicle at its centre, and then cut through the muscles which connect the scapula and arm with
the trunk — viz., the Pectoralis minor in front, Serratus magnus at the side, and the Levator
anguli scapulae, the Rhomboids, Trapezius, and Latissimus dorsi behind. These muscles should
be cleaned and traced to their respective insertions. Then make an incision through the integu-
ment, commencing at the outer third of the clavicle, and extending along the margin of that
bone, the acromion process, and spine of the scapula; the integument should be dissected from
above downward and outward, when the fascia covering the Deltoid is exposed (Fig. 311, No. 3).
472 THE MUSCLES AND FASCIAE
II. MUSCLES AND FASCIA OF THE SHOULDER AND ARM.
Superficial Fascia. — The superficial fascia of the upper extremity is a thin
cellulo-fibrous layer, containing the superficial veins and lymphatics, and the
cutaneous nerves. It is most distinct in front of the elbow, and contains very large
superficial veins and nerves ; in the hand it is hardly demonstrable, the integument
being closely adherent to the deep fascia by dense fibrous bands. Small sub-
cutaneous bursse are found in this fascia over the acromion, the olecranon, and
the knuckles.
Deep Fascia. — The deep fascia of the upper extremity comprises the aponeurosis
of the shoulder, arm, and forearm, the anterior and posterior annular ligaments of
the carpus, and the palmar fascia. These will be considered in the description
of the muscles of the several regions.
3. The Acromial Region.
Deltoid.
Deep Fascia. — The deep fascia covering the Deltoid, and known as the deltoid
aponeurosis, is a fibrous layer which covers the outer surface of the muscle, thick
and strong behind, where it is continuous with the infraspinatus fascia, thinner
over the rest of its extent. It sends down numerous prolongations between the
fasciculi of the muscle. In front, it is continuous with the fascia covering the
great Pectoral muscle; behind, with that covering the Infraspinatus; above, it
is attached to the clavicle, the acromion, and spine of the scapula; below, it is
continuous with the deep fascia of the arm.
The Deltoid (m. deltoideus) (Fig. 313) is a large, thick, triangular muscle, which
gives the rounded outline to the shoulder, and has received its name from its resem-
blance to the Greek letter A reversed. It surrounds the shoulder-joint in the greater
part of its extent, covering it on its outer side, and in front and behind. It arises
from the outer third of the anterior border and upper surface of the clavicle; from
the outer margin and upper surface of the acromion process, and from the lower lip
of the posterior border of the spine of the scapula, as far back as the triangular sur-
face at its inner end. From this extensive origin the fibres converge toward their
insertion, the middle passing vertically, the anterior obliquely backward, the pos-
terior obliquely forward; they unite to form a thick tendon, which is inserted into
a rough triangular prominence on the middle of the outer side of the shaft of the
humerus. At its insertion the muscle gives off an expansion to the deep fascia of
the arm. This muscle is remarkably coarse in texture, and the arrangement of
its muscular fibres is somewhat peculiar; the central portion of the muscle — that
is to say, the part arising from the acromion process— consists of oblique fibres,
which arise in a bipenniform manner from the sides of tendinous intersections,
generally four in number, which are attached above to the acromion process and
pass downward parallel to one another in the substance of the muscle. The
oblique muscular fibres thus formed are inserted into similar tendinous intersec-
tions, generally three in number, which pass upward from the insertion of the
muscle into the humerus and alternate with the descending septa. The portions
of the muscle which arise from the clavicle and spine of the scapula are not
arranged in this manner, but pass from their origin above, to be inserted into the
margins of the inferior tendon.
Relations.— By its superficial surface, with the integument, the superficial and
deep fasciae, Platysma, and supra-acromial nerves. Its deep surface is separated
THE ANTERIOR SCAPULAR REGION 473
•
from the head of the humerus by a large sacculated synovial bursa, the subdeltoid
bursa (bursa subdeltoid ea). It often communicates with the subacromial bursa
(bursa subacromialis), which is between the acromial process and the coraco-
acromial ligament above and the capsule of the shoulder-joint and the Supra-
spinatus muscle below. The deep surface of the deltoid covers the coracoid
process, coraco-acromial ligament, Pectoralis minor, Coraco-brachialis, both heads
of the Biceps, the tendon of the Pectoralis major, the insertions of the Supra-
spinatus, Infraspinatus, and Teres minor, the scapular and external heads of the
Triceps, the circumflex vessels and nerve, and the humerus. Its anterior border
is separated at its upper part from the Pectoralis major by a cellular interspace,
which lodges the cephalic vein and humeral branch of the acromial thoracic artery :
lower down the two muscles are in close contact. Its posterior border rests on the
Infraspinatus and Triceps muscles.
Nerves. — The Deltoid is supplied by the fifth and sixth cervical through the
circumflex nerve.
Actions. — The Deltoid raises the arm directly from the side, so as to bring it
at right angles with the trunk, but this act cannot be performed without the aid
of the Serratus magnus, which muscle steadies the lower angle of the scapula.
Its anterior fibres, assisted by the Pectoralis major, draw the arm forward; and its
posterior fibres, aided by the Teres major and Latissimus dorsi, draw it backward.
Surgical Anatomy. — The Deltoid is very liable to atrophy, and when in this condition
simulates dislocation of the shoulder-joint, as there is flattening of the shoulder and apparent
prominence of the acromion process; upon examination, however, it will be found that the
relative position of the great tuberosity of the humerus to the acromion and coracoid process is
unchanged. Atrophy of the Deltoid may be due to disuse or loss of trophic influence, either
from injury to the circumflex nerve or cord lesions, as in infantile paralysis.
4. The Anterior Scapular Region.
Subscapularis.
Dissection. — Divide the Deltoid across, near its upper part, by an incision carried along the
margin of the clavicle, the acromion process and spine of the scapula, and reflect it downward,
when the structures under cover of it will be seen.
The Subscapular Fascia (fascia subscapularis} . — The subscapular fascia is a
thin membrane attached to the entire circumference of the subscapular fossa, and
affording attachment by its inner surface to some of the fibres of the Subscapu-
laris muscle: when this is removed, the Subscapularis muscle is exposed.
The Subscapularis (Fig. 314) is a large triangular muscle which fills up the
subscapular fossa, arising from its internal two-thirds, with the exception of a
narrow margin along the posterior border, and the surfaces at the superior and
inferior angles which afford attachment to the Serratus magnus : it also arises from
the lower two-thirds of the groove on the axillary border of the bone. Some fibres
arise from tendinous laminae, which intersect the muscle, and are attached to ridges
on the bone; and others from an aponeurosis, which separates the muscles from the
Teres major and the long head of the Triceps. The fibres pass outward, and,
gradually converging, terminate in a tendon, which is inserted into the lesser
tuberosity of the humerus. Those fibres which arise from the axillary border of
the scapula are inserted into the neck of the humerus to the extent of an inch below
the tuberosity. The tendon of the muscle is in close contact with the anterior part
of the capsular ligament of the shoulder-joint, and glides over a large bursa, the
bursa of the subscapularis muscle (bursa m. subscapular is), which separates it from
the base of the coracoid process. This bursa communicates with the cavity of the
joint by an aperture in the capsular ligament.
474 THE MUSCLES AND FASCIJS
Relations. — Its anterior surface forms a considerable part of the posterior wall
of the axilla, and is in relation with the Serratus magnus, Coraco-brachialis, and
Biceps, the axillary vessels and brachial plexus of nerves, and the subscapular
vessels and nerves. By its posterior surface, with the scapula and the capsular
ligament of the shoulder-joint. Its lower border is contiguous with the Teres major
and Latissimus dorsi.
Nerves. — It is supplied by the fifth and sixth cervical nerves through the upper
and lower subscapular nerves.
Actions. — The Subscapularis rotates the head of the humerus inward; when
the arm is raised, it draws the humerus forward and downward. It is a powerful
defence to the front of the shoulder-joint, preventing displacement of the head of
the bone.
5. The Posterior Scapular Region (Fig. 315).
Supraspinatus. Teres minor.
Infraspinatus. Teres major.
Dissection. — To expose these muscles, and to examine their mode of insertion into the
humerus, detach the deltoid and Trapezius from their attachment to the spine of the scapula
and acromion process. Remove the clavicle by dividing the ligaments connecting it with the
coracoid process, and separate it at its articulation with the scapula: divide the acromion process
near its root with a saw. The fragments being removed, the tendons of the posterior Scapular
muscles will be fully exposed, and can be examined. A block should be placed beneath the
shoulder-joint, so as to make the muscles tense.
The Supraspinatus Fascia (fascia supraspinata) . — The supraspinatus fascia is
a thick and dense membranous layer, which completes the osseo-fibrous case
in which the Supraspinatus muscle is contained, affording attachment, by its
inner surface, to some of the fibres of the muscle. It is thick internally, but
thinner externally under the coraco-acromial ligament. When this fascia is
removed, the Supraspinatus muscle is exposed.
The Supraspinatus Muscle occupies the whole of the supraspinatus fossa,
arising from its internal two-thirds and from the strong fascia which covers its sur-
face. The muscular fibres converge to a tendon which passes across the upper
part of the capsular ligament of the shoulder-joint, to which it is intimately adher-
ent, and is inserted into the highest of the three facets on the great tuberosity of
the humerus.
Relations. — By its upper surface, with the Trapezius, the clavicle, the acromion,
the coraco-acromial ligament, and the Deltoid; by its under surface, with the
scapula, the suprascapular vessels and nerve, and upper part of the shoulder-joint.
The Infraspinatus Fascia (fascia infraspinata). — The infraspinatus fascia is
a dense fibrous membrane, covering in the Infraspinatus muscle and attached
to the circumference of the infraspinatus fossa; it affords attachment, by its inner
surface, to some fibres of that muscle. At the point where the Infraspinatus
commences to be covered by the Deltoid, this fascia divides into two layers: one
layer passes over the Deltoid muscle, helping to form the Deltoid fascia already
described ; the other passes beneath the Deltoid to the capsule of the shoulder-joint.
The Infraspinatus is a thick, triangular muscle, which occupies the chief part
of the infraspinatus fossa, arising by fleshy fibres from its internal two-thirds, and
by tendinous fibres from the ridges on its surfaces: it also arises from a strong
fascia which covers it externally, and separates it from the Teres major and minor.
The fibres converge to a tendon which glides over the external border of the
spine of the scapula, and, passing across the posterior part of the capsular ligament
of the shoulder-joint, is inserted into the middle facet on the great tuberosity of
the humerus. The tendon of this muscle has interposed between it and the joint
THE POSTERIOR SCAPULAR REGION
475
capsule a synovial bursa, the bursa of the Infraspinatus muscle (bursa m. infra-
xpinati), which communicates with the synovial cavity of the shoulder-joint.
Relations. — By its posterior surface, with the Deltoid, the Trapezius, Latissimus
dorsi, and the integument; by its anterior surface, with the scapula, from which
it is separated by the suprascapular and dorsalis scapulae vessels, and with the
FIG. 315. — Muscles on the dorsum of the Scapula and the Triceps.
capsular ligament of the shoulder-joint. Its lower border is in contact with the
Teres minor, occasionally united with it, and with the Teres major.
The Teres Minor is a narrow, elongated muscle, which arises from the dorsal
surface of the axillary border of the scapula for the upper two-thirds of its extent,
and from two aponeurotic laminae, one of which separates this muscle from the
Infraspinatus, the other from the Teres major; its fibres pass obliquely upward
and outward, and terminate in a tendon which is inserted into the lowest of the
three facets on the great tuberosity of the humerus, and, by fleshy fibres, into the
humerus immediately below it. The tendon of this muscle passes across the
posterior part of the capsular ligament of the shoulder-joint.
Relations. — By its posterior surface, with the Deltoid and the integument;
by its anterior surface, with the scapula and dorsal branch of the subscapular
artery, the long head of the Triceps, and the shoulder-joint; by its upper border,
with the Infraspinatus; by its lower border, with the Teres major, from which it
is separated anteriorly by the long head of the Triceps.
The Teres Major is a thick but somewhat flattened muscle, which arises from
the oval surface on the dorsal aspect of the inferior angle of the scapula, and from
the fibrous septa interposed between it and the Teres minor and Infraspinatus; the
476
fibres are directed upward and outward, and terminate in a flat tendon, about two
inches in length, which is inserted into the inner bicipital ridge of the humerus.
The tendon of this muscle, at its insertion into the humerus, lies behind that of the
Latissimus dorsi, from which it is separated by a synovial bursa, the bursa of the
Latissimus dorsi muscle (bursa m. latissimi dorsi), the two tendons being, however,
united along their lower borders for a short distance. Between the tendon of
the Teres major and the bone is the bursa m. teretis majoris.
Relations. — By its posterior surface, with the Latissimus dorsi below, and the
long head of the Triceps above. By its anterior surface, with the Subscapularis,
Latissimus dorsi, Coraco-brachialis, short head of the Biceps, the axillary vessels,
and brachial plexus of nerves. Its upper border is at first in relation with the
Teres minor, from which it is afterward separated by the long head of the Triceps.
Its lower border forms, in conjunction with the Latissimus dorsi, part of the pos-
terior boundary of the axilla. The Latissimus dorsi at first covers the origin of
the Teres major, then wraps itself obliquely round its lower border, so that its
tendon ultimately comes to lie in front of that of the Teres major.
Nerves. — The Supra- and Infraspinatus muscles are supplied by the fifth and
sixth cervical nerves through the suprascapular nerve; the Teres minor, by the
fifth cervical, through the circumflex; and the Teres major, by the fifth and sixth
cervical, through the lower subscapular.
Actions. — -The Supraspinatus assists the Deltoid in raising the arm from the
side, and fixes the head of the humerus in the glenoid cavity. The Infraspinatus
and Teres minor rotate the head of the humerus outward : when the arm is raised,
they assist in retaining it in that position and carrying it backward. One of the
most important uses of these three muscles is the great protection they afford to
the shoulder-joint, the Supraspinatus supporting it above, and preventing displace-
ment of the head of the humerus upward, while the Infraspinatus and Teres minor
protect it behind, and prevent dislocation backward. The Teres major assists the
Latissimus dorsi in drawing the humerus downward and backward, when pre-
viously raised, and rotating it inward; when the arm is fixed, it may assist the
Pectoral and Latissimus dorsi muscles in drawing the trunk forward.
THE MUSCLES AND FASCIA OF THE ARM.
6. The Anterior Humeral Region (Fig. 314).
Coraco-brachialis. Biceps. Brachialis anticus.
Dissection. — The arm being placed on the table, with the front surface uppermost, make
a vertical incision through the integument along the middle line, from the clavicle to about
two inches below the elbow-joint, where it should be joined by a transverse incision, extending
from the inner to the outer side of the forearm; the two flaps being reflected on either side,
the fascia should be examined (Fig. 311).
Deep Fascia (fascia brachii). — The deep fascia of the arm is continuous with
that covering the Deltoid and the great Pectoral muscles, by means of which it is
attached, above, to the clavicle, acromion, and spine of the scapula, and is also
continuous with the axillary fascia. It forms a thin, loose, membranous sheath
investing the muscles of the arm, sending down septa between them, and com-
posed of fibres disposed in a circular or spiral direction, and connected together
by vertical and oblique fibres. It differs in thickness at different parts, being
thin over the Biceps, but thicker where it covers the Triceps, and over the
condyles of the humerus; it is strengthened by fibrous aponeuroses, derived
from the Pectoralis major and Latissimus dorsi on the inner side, and from the
Deltoid externally. On either side it gives off a strong intermuscular septum,
THE ANTERIOR HUMERAL REGION 477
which is attached to the supracondylar ridge and condyle of the humerus. These
septa serve to separate the muscles of the anterior from those of the posterior
brachial region. The external intermuscular septum (septum intermusculare
laterale) extends from the lower part of the anterior bicipital ridge, along the
external supracondylar ridge, to the outer condyle; it is blended with the tendon
of the Deltoid, gives attachment to the Triceps behind, to the Brachialis anticus,
Supinator longus, and Extensor carpi radialis longior, in front, and is perforated
by the musculo-spiral nerve and superior profunda artery. The internal inter-
muscular septum (septum intermusculare mediate), thicker than the preceding,
extends from the lower part of the posterior lip of the bicipital groove below the
Teres major, along the internal supracondylar ridge to the inner condyle; it is
blended with the tendon of the Coraco-brachialis, and affords attachment to the
Triceps behind, and the Brachialis anticus in front. It is perforated by the ulnar
nerve and the inferior profunda and anastomotic arteries. At the elbow the deep
fascia is attached to all the prominent points round the joint — viz., the condyles of
the humerus and the olecranon process of the ulna — and is continuous with the
deep fascia of the forearm. Just below the middle of the arm, on its inner side, in
front of the intermuscular septum, is an oval opening in the deep fascia which
transmits the basilic vein and some lymphatic vessels. On the removal of this
fascia the muscles, vessels, and nerves of the anterior humeral region are exposed.
The Coraco-brachialis, the smallest of the three muscles in this region, is
situated at the upper and inner part of the arm. It arises by fleshy fibres from
the apex of the coracoid process, in common with the short head of the Biceps,
and from the intermuscular septum between the two muscles; the fibres pass
downward, backward, and a little outward, to be inserted by means of a flat
tendon into an impression at the middle of the inner surface and internal border
of the shaft of the humerus between the origins of the Triceps and Brachialis
anticus. It is perforated by the musculo-cutaneous nerve. The inner border of
the muscle forms a guide to the position of the brachial artery in tying the vessel
in the upper part of its course. Between the tendon of the subscapularis,
the coracoid process and the tendon of the Coraco-brachialis, is the bursa of the
Coraco-brachialis muscle (bursa m. coracobrachialis).
Relations. — By its anterior surface, with the Pectoralis major above, and at
its insertion with the brachial vessels and median nerve which cross it; by its
posterior surface, with the tendons of the Subscapularis, Latissimus dorsi, and
Teres major, the inner head of the Triceps, the humerus, and the anterior circum-
flex vessels; by its inner border, with the brachial artery, and the median and
musculo-cutaneous nerves; by its outer border, with the short head of the Biceps
and Brachialis anticus.
The Biceps or the Biceps Flexor Cubiti (m. biceps brachii) is a long fusiform
muscle, occupying the whole of the anterior surface of the arm, and divided above
into two portions or heads, from which circumstance it has received its name. The
short head (caput breve) arises^by a thick flattened tendon from the apex of the cora-
coid process, in common with the Coraco-brachialis. The long head (caput longum)
arises from the upper margin of the glenoid cavity, and is continuous with the
glenoid ligament. This tendon arches over the head of the humerus, being enclosed
in a special sheath of thesynovial membrane of the shoulder-joint; it then passes
through an opening in the capsular ligament at its attachment to the humerus,
and descends in the bicipital groove, in which it is retained by a fibrous prolonga-
tion from the tendon of the Pectoralis major. Each tendon is succeeded by an
elongated muscular belly, and the two bellies, although closely applied to each
other, can readily be separated until within about three inches of the elbow-joint.
Here they end in a flattened tendon, which is inserted into the back part of the
tuberosity of the radius, a synovial bursa (bursa bicipitoradialis) , being interposed
478 THE MUSCLES AND FASCIA
between the tendon and the front of the tuberosity, and another bursa (bursa
cubitalis interossea) is often interposed between the ulna and the tendon. As the
tendon of the muscle approaches the radius it becomes twisted upon itself, so that
its anterior surface becomes external and is applied to the tuberosity of the
radius at its insertion : opposite the bend of the elbow the tendon gives off, from
its inner side, a broad aponeurosis, the bicipital or semilunar fascia (lacertus
fibrosus), which passes obliquely downward and inward across the brachial
artery, and is continuous with the deep fascia of the forearm (Fig. 313). The
inner border of this muscle forms a guide to the position of the vessel in tying the
brachial artery in the middle of the arm.1
Relations. — Its anterior surface is overlapped above by the Pectoralis major
and Deltoid; in the rest of its extent it is covered by the superficial and deep
fasciae and the integument. Its posterior surface rests above on the shoulder-
joint and upper part of the humerus; below it rests on the Brachialis anticus,
with the musculo-cutaneous nerve intervening between the two, and on the
Supinator brevis. Its inner border is in relation with the Coraco-brachialis, and
overlaps the brachial vessels and median nerve; its outer border, with the Deltoid
and Supinator longus.
The Brachialis Anticus (ra. brachialis) is a broad muscle, which covers the elbow-
joint and the lower half of the front of the humerus. It is somewhat compressed
from before backward, and is broader in the middle than at either extremity. It
urises from the lower half of the outer and inner surfaces of the shaft of the humerus,
and commences above at the insertion of the Deltoid, which it embraces by two
angular processes. Its origin extends below, to within an inch of the margin of
the articular surface, and is limited on each side by the external and internal
borders of the shaft of the humerus. It also arises from the intermuscular septa
on each side, but more extensively from the inner than the outer, from which it is
separated below by the Supinator longus and Extensor carpi radialis longior. Its
fibres converge to a thick tendon, which is inserted into a rough depression on
the anterior surface of the coronoid process of the ulna, being received into an
interval between two fleshy slips of the Flexor profundus digitorum.
Relations. — By its anterior surface, with the Biceps, the brachial vessels, mus-
culo-cutaneous, and median nerves; by its posterior surface, with the humerus
and front of the elbow-joint; by its inner border, with the Triceps, ulnar nerve,
and Pronator radii teres, from which it is separated by the intermuscular septum;
by its outer border, with the musculo-spiral nerve, radial recurrent artery, the
Supinator longus, and Extensor carpi radialis longior.
Nerves. — The muscles of this group are supplied by the musculo-cutaneous
nerve. The Brachialis anticus usually receives an additional filament from the
musculo-spiral. The Coraco-brachialis receives its supply primarily from the
seventh cervical, the Biceps and Brachialis anticus from the fifth and sixth cer-
vical nerves.
Actions. — The Coraco-brachialis draws the humerus forward and inward, and
at the same time assists in elevating it toward the scapula. The Biceps is a flexor
of the forearm; it is also a powerful supinator, and serves to render tense the
deep fascia of the forearm by means of the broad aponeurosis given off from
its tendon. The Brachialis anticus is a flexor of the forearm, and forms an impor-
tant defence to the -elbow-joint. When the forearm is fixed, the Biceps and
Brachialis anticus flex the arm upon the forearm, as is seen in efforts at climbing.
THE POSTERIOR HUMERAL REGION 479
7. The Posterior Humeral Region.
Triceps. Subanconeus.
The Triceps or the Triceps Extensor Cubiti (m. triceps brachii) (Fig. 315) is
situated on the back of the arm, extending the entire length of the posterior surface
of the huraerus. It is of large size, and divided above into three parts ; hence its
name. These three portions have been named (1) the middle, scapular, or long head ;
(2) the external or long humeral head; and (3) the internal or short humeral head.
The Middle, Long, or Scapular Head (caput longum) arises, by a flattened tendon,
from a rough triangular depression on the scapula, immediately below the glenoid
cavity, being blended at its upper part with the capsular ligament; the muscular
fibres pass downward between the two other portions of the muscle, and join with
them in the common tendon of insertion.
The External Head (caput laterale) arises from the posterior surface of the shaft
of the humerus, between the insertion of the Teres minor and the upper part of
the musculo-spiral groove; from the external border of the humerus and the
external intermuscular septum: the fibres from this origin converge toward the
common tendon of insertion.
The Internal Head (caput mediale) arises from the posterior surface of the shaft
of the humerus, below the groove for the musculo-spiral nerve; commencing above,
narrow and pointed, below the insertion of the Teres major, and extending to
within an inch of the trochlear surface: it also arises from the internal border of
the humerus, and from the back of the whole length of the internal and lower part
of the external intermuscular septum. The fibres of this portion of the muscle are
directed, some downward to the olecranon, whilst others converge to the common
tendon of insertion.
The Common Tendon of the Triceps commences about the middle of the back part
of the muscle : it consists of two aponeurotic laminae, one of which is subcutaneous
and covers the posterior surface of the muscle for the lower half of its extent; the
other is more deeply seated in the substance of the muscle: after receiving the
attachment of the muscular fibres, they join together above the elbow, and are
inserted, for the most part, into the back part of the upper surface of the olecranon
process; a band of fibres is, however, continued downward, on the outer side,
over the Anconeus, to blend with the deep fascia of the forearm. A small bursa
(bursa subtendinea olecrani) occasionally multilocular, is situated on the front part
of this surface, beneath the tendon. The subcutaneous olecranon bursa (bursa sub-
cutanea olecrani) is situated between the olecranon process and the skin. Within
the tendon of the triceps is often found the bursa intratendinea olecrani.
The long head of the Triceps descends between the Teres minor and Teres
major, dividing the triangular space between these two muscles and the humerus
into two smaller spaces, one triangular, the other quadrangular (Fig. 315). The
triangular space contains the dorsalis scapulas vessels; it is bounded by the Teres
minor above, the Teres major below, and the scapular head of the Triceps exter-
nally: the quadrangular space transmits the posterior circumflex vessels and the
circumflex nerve; it is bounded by the Teres minor above, the Teres major below,
the scapular head of the Triceps internally, and the humerus externally.
Relations. — By its posterior surface, with the Deltoid above: in the rest of its
extent it is subcutaneous; by its anterior surface, with the humerus, musculo-
spiral nerve, superior profunda vessels, and back part of the elbow-joint. Its
middle or long head is in relation, behind, with the Deltoid and Teres minor; in
front, with the Subscapularis, Latissimus dorsi, and Teres major.
480 THE MUSCLES AND FASCIA
The Subanconeus (ra. anconaeus) is a name given to a few fibres from the under
surface of the lower part of the Triceps muscle, which are inserted into the posterior
ligament of the elbow-joint. By some authors it is regarded as the analogue of
the Subcrureus in the lower limb, but it is not a separate muscle.
Nerves. — The Triceps is supplied by the seventh and eighth cervical nerves
through the musculo-spiral nerve.
Actions. — The Triceps is the great extensor muscle of the forearm, serving,
when the forearm is flexed, to extend the elbow-joint. It is the direct antagonist
of the Biceps and Brachialis anticus. When the arm is extended the long head
of the muscles may assist the Teres major and Latissimus dorsi in drawing the
humerus backward and in adducting it to the thorax. The long head of the Tri-
ceps protects the under part of the shoulder-joint, and prevents displacement of
the head of the humerus downward and backward. The Subanconeus draws
up the posterior ligament during extension of the forearm.
Surgical Anatomy. — The existence of the band of fibres from the Triceps to the fascia of
the forearm is of importance in excision of the elbow, and should always be carefully preserved
from injury by the operator, as by means of these fibres the patient is enabled to extend the
forearm, a movement which would otherwise mainly be accomplished by gravity; that is to say,
allowing the forearm to drop from its own weight.
III. MUSCLES AND FASCI-ffi OF THE FOREARM.
Dissection. — To dissect the forearm, place the limb in the position indicated in Fig. 311,
make a vertical incision along the middle line from the elbow to the wrist, and a transverse
incision at the extremity of this; the superficial structures being removed, the deep fascia of
the forearm is exposed.
Deep Fascia (fascia antibrachii). — The deep fascia of the forearm, continuous
above with that enclosing the arm, is a dense, highly glistening aponeurotic
investment, which forms a general sheath enclosing the muscles in this region;
it is attached, behind, to the olecranon and posterior border of the ulna, and gives
off from its inner surface numerous intermuscular septa, which enclose each mus-
cle separately. Below, it is continuous in front with the anterior annular ligament
(lig amentum carpi volare) , and forms a sheath for the tendon of the Palmaris longus
muscle, which passes over the annular ligament to be inserted into the palmar
fascia. Behind, near the wrist-joint, it becomes much thickened by the addition
of many transverse fibres, and forms the posterior annular ligament (ligamentum
carpi dorsale). It consists of circular and oblique fibres, connected together by
numerous vertical fibres. It is much thicker on the dorsal than on the palmar sur-
face, and at the lower than at the upper part of the forearm, and is strengthened
above by tendinous fibres derived from the Brachialis anticus and Biceps in front,
and from the Triceps behind. Its deep surface gives origin to muscular fibres,
especially at the upper part of the inner and outer sides of the forearm, and forms
the boundaries of a series of conical-shaped cavities, in which the muscles are
contained. Besidesjthe vertical septa separating each muscle, transverse septa are
given off on the anterior and posterior surfaces of the forearm, separating the
deep from the superficial layer of muscles. Numerous apertures exist in the fascia
for the passage of vessels and nerves; one of these, of large size, situated at the
front of the elbow, serves for the passage of a communicating branch between
the superficial and deep veins.
The muscles of the forearm may be subdivided into groups corresponding to
the region they occupy. One group occupies the inner and anterior aspect of the
forearm, and comprises the Flexor and Pronator muscles. Another group occupies
its outer side, and a third its posterior aspect. The two latter groups include all
the Extensor and Supinator muscles.
THE ANTERIOR RADIO -ULNAR REGION 481
8. The Anterior Radio-ulnar Region.
The muscles in this region are divided for convenience of description into two
groups or layers, superficial and deep.
The Superficial Layer.
Pronator radii teres. Palmaris longus.
Flexor carpi radialis. Flexor carpi ulnaris.
Flexor sublimis digitorum.
These muscles take origin from the internal condyle of the humerus by a
common tendon.
The Pronator Radii Teres (m. pronator teres) arises by two heads. One, the
larger and more superficial, humeral head (caput humerale), arises from the humerus,
immediately above the internal condyle, and from the tendon common to the
origin of the other muscles ; also from the fascia of the forearm and the inter-
muscular septum between it and the Flexor carpi radialis. The other head, the
ulnar head (caput idnare), is a thin fasciculus which arises from the inner side of
the coronoid process of the ulna, joining the preceding at an acute angle.
Between the two heads the median nerve enters the forearm. The muscle passes
obliquely across the forearm from the inner to the outer side, and terminates in a
flat tendon, which turns over the outer margin of the radius, and is inserted into
a rough impression at the middle of the outer surface of the shaft of that bone.
Relations. — By its anterior surface, throughout the greater part of its extent,
with the deep fascia; at its insertion it is crossed by the radial vessels and nerve,
and is covered by the Supinator longus; by its posterior surface, with the Brachialis
anticus, Flexor sublimis digitorum, the median nerve, and ulnar artery, the small
or deep head being interposed between the two latter structures. Its outer border
forms the inner boundary of a triangular space in which are placed the brachial
artery, median nerve, and tendon of the Biceps muscle. Its inner border is in
contact with the Flexor carpi radialis.
Surgical Anatomy. — This muscle, when suddenly brought into very active use, as in the
game of lawn tennis, is apt to be strained, producing slight swelling and tenderness, and pain
on putting the muscle into action. This is known as lawn-tennis arm.
The Flexor Carpi Radialis lies on the inner side of the preceding muscle. It
arises from the internal condyle by the common tendon, from the fascia of the fore-
arm, and from the intermuscular septa between it and the Pronator radii teres, on
the outside, the Palmaris longus internally, and the Flexor sublimis digitorum
beneath. Slender and aponeurotic in structure at its commencement, it increases
in size, and terminates in a tendon which forms rather more than the lower half
of its length. This tendon passes through a canal on the outer side of the annular
ligament, runs through a groove in the os trapezium (which is converted into a
canal by a fibrous sheath, and is lined by a synovial membrane), and is inserted
into the base of the metacarpal bone of the index finger, and by a slip into the base
of the metacarpal bone of the middle finger. The radial artery lies between the
tendon of this muscle and the Supinator longus, and may easily be tied in this
situation. In the hand a bursa (bursa m. flexoris carpi radialis) lies between the
base of the second metacarpal bone and the tendon (Spalteholz) .
Relations. — By its superficial surface, with the deep fascia and the integument;
by its deep surface, with the Flexor sublimis digitorum, Flexor longus pollicis,
and wrist-joint ; by its outer border, with the Pronator radii teres and the radial
vessels; by its inner border, with the Palmaris longus above and the median
nerve below.
31
482
THE MUSCLES AND FASCIA
The Palmaris Longus (Fig. 316) is a slender, fusiform muscle lying on the inner-
side of the preceding. It arises from the inner condyle of the humerus by the com-
mon tendon, from the deep fascia, and the inter-
muscular septa between it and the adjacent mus-
cles. It terminates in a slender flattened tendon,
which passes over the upper part of the annular
ligament, to end in the central part of the palmar
fascia and lower part of the annular ligament,
frequently sending a tendinous slip to the short
muscles of the thumb. This muscle is often
absent, and is subject to very considerable varia-
tions; it may be tendinous above and muscular
below; or it may be muscular in the centre, with
a tendon above and below; or it may present two
muscular bundles with a central tendon; or
finally it may consist simply of a mere tendinous
band.
Relations. — By its superficial surface, with the
deep fascia. By its deep surface, with the Flexor
sublimis digitorum. Internally, with the Flexor
carpi ulnaris. Externally, with the Flexor carpi
radialis. The median nerve lies close to the
tendon, just above the wrist, on its inner and
posterior side.
The Flexor Carpi Ulnaris (Fig. 316) lies along
the ulnar side of the forearm. It arises by two
heads, connected by a tendinous arch, beneath
which pass the ulnar nerve and posterior ulnar
recurrent artery. One head arises from the inner
condyle of the humerus, humeral head (caput
humerale) , by the common tendon ; the other from
the inner margin of the olecranon and from the
upper two-thirds of the posterior border of the
ulna, ulnar head (caput ulnar e], by an aponeu-
rosis, common to it and the Extensor carpi
ulnaris and Flexor profundus digitorum; and from
the intermuscular septum between it and the
Flexor sublimis digitorum. The fibres terminate
in a tendon which occupies the anterior part of
the lower half of the muscle, and is inserted into
the pisiform bone, and is prolonged from this to
the fifth metacarpal and unciform bones, by the
piso-metacarpal and piso-uncinate ligaments: it is
also attached by a few fibres to the annular liga-
ment. The ulnar artery lies on the outer side of
the tendon of this muscle, in the lower two-thirds
of the forearm, the tendon forming a guide in tying the vessel in this situation.
A bursa (bursa m. flexoris carpi ulnaris) is placed between the tendon and a
part of the pisiform bone.
Relations. — By its superficial surface, with the deep fascia, with which it is
intimately connected for a considerable extent; by its deep surface, with the Flexor
sublimis digitorum, the Flexor profundus digitorum, the Pronator quadratus, and
the ulnar vessels and nerve; by its outer or radial border, with the Palmaris longus
above and the ulnar vessels and nerve below.
FIG. 316.— Front of the left forearm.
Superficial muscles.
THE ANTERIOR RADIO- ULNAR REGION
483
The Flexor Sublimis Digitorum (m. flexor digitorum sublimis) (Fig. 316)
is placed beneath the preceding muscles, which therefore must be removed
in order to bring its attachment into view. It is the largest of the muscles of the
superficial layer, and arises by t. iree heads. One head, the humeral head (caput
humerale) , arises from the internal condyle of the humerus by the common ten-
don, from the internal lateral ligament of the elbow-joint, and from the intermus-
cular septum common to it and the preceding muscles. The second head, ulnar
head (caput ulnare), arises from the inner side of the coronoid process of the ulna,
above the ulnar origin of the Pronator radii teres (Fig. 134, p. 187). The third
head, radial head (caput radiate), arises from the oblique line of the radius, extend-
ing from the tuberosity to the insertion of the Pronator radii teres. The fibres pass
vertically downward, forming a broad and thick muscle, which speedily divides into
two planes of muscular fibres, superficial and deep: the superficial plane divides
into two parts which end in tendons for the middle and ring fingers; the deep
plane also divides into two parts, which end in tendons for the index and little
fingers, but previously to having done so it gives off a muscular slip, which joins
that part of the superficial plane which is intended for the ring finger. As the
four tendons thus formed pass beneath the annular ligament into the palm of the
hand, they are arranged in pairs, the superficial pair corresponding to the middle
and ring fingers, the deep pair to the index and little fingers. The tendons diverge
from one another as they pass onward. Opposite the bases of the first phalanges
each tendon divides into two slips (chiasma tendinum) to allow of the passage of
the corresponding tendon of the Flexor profundus digitorum; the two portions of
the tendon then unite and form a grooved channel for the reception of the accom-
panying deep flexor tendon. Finally they subdivide a second time, to be inserted
into the sides of the second phalanges
about their middle. The insertion in the
index finger is shown in Fig. 322. After
leaving the palm the tendons of the
superficial flexor, accompanied by the deep
flexor tendons, lie in osseo-aponeurotic
canals (Fig. 318). Each canal or theca
extends from the metacarpo-phalangeal
articulation to the proximal end of the
distal phalanx (Fig. 232). It is formed
by strong fibrous bands, which arch across
the tendons, and are attached on each side
to the margins of the phalanges. Oppo-
site the middle of the proximal and second
phalanges the sheath is very strong, and
the fibres pass transversely; but opposite the joints it is much thinner, and the
fibres pass obliquely. It is very thin over the metacarpo-phalangeal articulation.
It is absent over the distal phalanx. Each sheath is lined by a synovial mem-
brane, which is reflected on the contained tendons.
Relations. — In the forearm, by its superficial surface, with the deep fascia and
all the preceding superficial muscles; by its deep surface, with the Flexor profundus
digitorum, Flexor longus pollicis, the ulnar vessels and nerve, and the median
nerve. In the hand its tendons are in relation, in front, with the palmar fascia,
superficial palmar arch, and the branches of the median nerve; behind, with the
tendons of the deep Flexor and the Lumbricales.
SHEATH OF,,
FLEXOR'
TENDONS
FLEXOR PROFUNDUS
DIGIT,ORUM
/FLEXOR
SUBLIMIS
DIGITORUM
DIGITAL
ARTERIES
AND NERVES
COMMON TENDON OF
EXTENSOR MUSCLE
OF FINGERS
FIRST PHALANX
FIG. 317. — Section passing through the middle
third of the first phalanx of the middle finger (frozen
section). The tendon of the Flexor sublimis digi-
torum is divided into two small bands, which spread
laterally and engage themselves between the osse-
Flexor profundus digitorum.
484 THE MUSCLES AND FASCIAE
The Deep Layer (Fig. 318).
Flexor profundus digitorum. Flexor longus pollicis.
Pronator quadratus.
Dissection. — Divide each of the superficial muscles at its centre, and turn either end aside;
the deep layer of muscles, together with the median nerve and ulnar vessels, will then be exposed.
The Flexor Profundus Digitorum (TO. flexor digitorum profundus) (Fig. 318)
is situated on the ulnar side of the forearm, immediately beneath the superficial
Flexors. It arises from the upper three-fourths of the anterior and inner
surfaces of the shaft of the ulna, embracing the insertion of the Brachialis anticus
above, and extending, below, to within a short distance of the Pronator quadratus.
It also arises from a depression on the inner side of the coronoid process; by an apo-
neurosis from the upper three-fourths of the posterior border of the ulna, in common
with the Flexor and Extensor carpi ulnaris ; and from the ulnar half of the inter-
osseous membrane. The fibres form a fleshy belly of considerable size, which divides
into four tendons : these pass under the annular ligament beneath the tendons of the
Flexor sublimis digitorum. Opposite the first phalanges the tendons pass through
the openings in the two slips of the tendons of the Flexor sublimis digitorum, and
are finally inserted into the bases of the last phalanges. The portion of the muscle
for the index finger (Fig. 322) is usually distinct throughout, but the tendons for
the three inner fingers are connected together by cellular tissue and tendinous slips
as far as the palm of the hand. The tendons of this muscle and those of the Flexor
sublimis digitorum, whilst contained in the osseo-aponeurotic canals of the fingers,
are invested in a synovial sheath, and are connected to each other and to the
phalanges by slender tendinous filaments, called vincula accessoria tendinum (vin-
culum tendinum). One of these connects the deep tendon to the bone before it
passes through the superficial tendon ; a second connects the two tendons together,
after the deep tendons have passed through; and a third connects the deep ten-
don to the head of the second phalanx. This last consists largely of yellow elastic
tissue, and may assist in drawing down the tendon after flexion of the finger.1
Four small muscles, the Lumbricales, are connected with the tendons of the Flexor
profundus in the palm. They will be described with the muscles in that region.
Relations. — By its superficial surface, in the forearm, with the Flexor sublimis
digitorum, the Flexor carpi ulnaris, the ulnar vessels and nerve, and the median
nerve; and in the hand, with the tendons of the superficial Flexor; by its deep
surface, in the forearm, with the ulna, the interosseous membrane, the Pronator
quadratus; and in the hand, with the Interossei, Adductor pollicis, and deep
palmar arch; by its ulnar border, with the Flexor carpi ulnaris; by its radial border,
with the Flexor longus pollicis, the anterior interosseous vessels and nerve being
interposed.
The Flexor Longus Pollicis (TO. flexor pollicis longus} (Fig. 318) is situated on
the radial side of the forearm, lying on the same plane as the preceding. It arises
from the grooved anterior surface of the shaft of the radius, commencing above,
immediately below the tuberosity and oblique line, and extending below to within
a short distance of the Pronator quadratus. It also arises from the adjacent part
of the interosseous membrane and generally by a fleshy slip from the inner border
of the coronoid process or from the internal condyle of the humerus. The fibres
pass downward, and terminate in a flattened tendon which passes beneath the
annular ligament, is then lodged in the interspace between the outer head of the
Flexor brevis pollicis and the Adductor obliquus pollicis, and, entering an osseo-
aponeurotic canal similar to those for the other flexor tendons, is inserted into the
base of the last phalanx of the thumb.
1 Marshall, Brit, and For. Med -Chir. Rev., 1853.
THE ANTERIOR RADIO- ULNAR REGION
485
Relations. — By its superficial sur-
face, with the Flexor sublimis digi-
torum, Flexor carpi radialis, Supi-
nator longus, and radial vessels; by
its deep surface, with the radius,
interosseous membrane, and Pro-
nator quadratus ; by its ulnar border,
with the Flexor profundus digitorum,
from which it is separated by the
anterior interosseous vessels and
nerve.
The Pronator Quadratus (Figs.
318 and 327) is a small, flat, quadri-
lateral muscle, extending transversely
across the front of the radius and
ulna, above their carpal extremities.
It arises from the oblique or pronator
ridge on the lower part of the ante-
rior surface of the shaft of the ulna;
from the lower fourth of the anterior
surface and the anterior border of
the ulna; and from a strong aponeu-
rosis which covers the inner third of
the muscle. The fibres pass out-
ward and slightly downward, to be
inserted into the lower fourth of the
anterior surface and anterior border
of the shaft of the radius.
Relations. — By its superficial sur-
face, with the Flexor profundus digi-
torum, the Flexor longus pollicis,
Flexor carpi radialis, and the radial
vessels; by its deep surface, with the
radius, ulna, and interosseous mem-
brane.
Nerves. — All the muscles of the
superficial layer are supplied by the
median nerve, excepting the Flexor
carpi ulnaris, which is supplied by the
ulnar nerve. The Pronator radii teres
and the Flexor carpi radialis derive
their supply primarily from the sixth
cervical; the Palmaris longus from
the eighth cervical; the Flexor sub-
limis digitorum from the seventh and
eighth cervical and first thoracic, and
the Flexor carpi ulnaris from the
eighth cervical and first thoracic
nerves. Of the deep layer, the Flexor
profundus digitorum is supplied by
the eighth cervical and first thoracic
through the ulnar and anterior in-
terosseous branch of the median.
The remaining two muscles, the
FIG. 318. — Front of the left forearm. Deep muscles.
486 THE MUSCLES AND FASCIJE
Flexor longus pollicis and Pronator quadratus, are also supplied by the eighth
cervical and first thoracic through the anterior interosseous branch of the median.
Actions. — These muscles act upon the forearm, the wrist, and hand. The
Pronator radii teres helps to rotate the radius upon the ulna, rendering the hand
prone: when the radius is fixed it assists the other muscles in flexing the forearm.
The Flexor carpi radialis is one of the flexors of the wrist; when acting alone it
flexes the wrist, inclining it to the radial side. It can also assist in pronating the
forearm and hand, and, by continuing its action, in bending the elbow. The Flexor
carpi ulnaris is one of the flexors of the wrist : when acting alone it flexes the wrist,
inclining it to the ulnar side (adducts the wrist), and, by continuing to contract,
it bends the elbow. The Palmaris longus is a tensor of the palmar fascia, and
tension of this fascia protects the parts beneath it. It also assists in flexing the
wrist and elbow. The Flexor sublimis digitorum flexes the middle phalanx and
then assists in flexing the wrist and elbow. The Flexor profundus digitorum is
the flexor of the distal phalanx. After the Flexor sublimis has bent the second
phalanx, the Flexor profundus flexes the terminal one, but it cannot do so until
after the contraction of the superficial muscle. After flexing the distal phalanx,
it assists in flexing the middle phalanx, the proximal phalanx, and the wrist. The
Flexor longus pollicis is the flexor of the distal phalanx of the thumb. When the
thumb is fixed it also assists in flexing the wrist. The Pronator quadratus helps
to rotate the radius upon the ulna, rendering the hand prone.
Surgical Anatomy. — When a finger is amputated so that the fibrous sheath of the flexor ten-
dons is divided in a region in which it is firm and dense, the tendon contracts but the theca does
not, and the rigid theca constitutes a permeable passage to the palm. If the parts should be
infected the theca will draw pus toward the palm. Hence it is best to close the theca by sutures.
"Over the terminal phalanx, and over the joint between the middle and terminal phalanges,
there is no fibrous sheath. In front of the metacarpo-phalangeal joint it is scarcely evident.
Over the first and second (proximal and middle) phalanges, and in front of the joint between
these bones, the fibrous sheath is well marked, and appears as a rigid tube when cut across.
As the sheath crosses the metacarpo-phalangeal and first interphalangeal joints, it is adherent
to the glenoid ligament, and is easily closed by two fine catgut sutures passed vertically — i. e.,
from the dorsal to the palmar wall. Opposite the shafts of the first and second phalanges,
however, there is much difficulty in effecting closure, since the sheath is united to the periosteum,
and that membrane is very thin. In these situations the periosteum should be stripped up a
little from the palmar aspect of the bone, and the orifice of the tube secured by two fine sutures
passed either vertically or transversely, as may appear the more convenient. This stripping
off of periosteum should be effected before the bone is divided."1
9. The Radial Region (Figs. 316, 319, 320).
Supinator longus. Extensor carpi radialis longior.
Extensor carpi radialis brevior.
Dissection. — Divide the integument in the same manner as in the dissection of the anterior
brachial region, and, after having examined the cutaneous vessels and nerves and deep fascia,
remove all those structures. The muscles will then be exposed. The removal of the fascia
will be considerably facilitated by detaching it from below upward. Great care should be
taken to avoid cutting across the tendons of the muscles of the thumb, which cross obliquely
the larger tendons running down the back of the radius.
The Supinator Longus (m. brachioradialis) (Fig. 316) is the most superficial
muscle on the radial side of the forearm; it is fleshy for the upper two-thirds of
its extent, tendinous below. It arises from the upper two-thirds of the external
supracondylar ridge of the humerus, and from the external intermuscular septum,
being limited above by the musculo-spiral groove. The fibres terminate above
the middle of the forearm in a flat tendon, which is inserted into the outer side
of the base of the styloid process of the radius.
1 Operative Surgery. By Sir Frederick Treves.
THE RADIAL REGION
Relations. — By its superficial sur-
face, with the integument and fascia
for the greater part of its extent; near
its insertion it is crossed by the Ex-
tensor ossis metacarpi pollicis and the
Extensor brevis pollicis; by its deep
surface, with the humerus, the Ex-
tensor carpi radialis longior and bre-
vior, the insertion of the Pronator
radii teres, and the Supinator brevis;
by its inner border, above the elbow,
with the Brachialis anticus, the mus-
culo-spiral nerve, and the radial recur-
rent artery; and in the forearm with
the radial vessels and nerve.
The Extensor Carpi Radialis
Longior (m. extensor carpi radialis
lonrfus] (Fig. 319) is placed partly
beneath the preceding muscle. It
arises from the lower third of the ex-
ternal supracondylar ridge of the
humerus, and from the external in-
termuscular septum by a few fibres
from the common tendon of origin of
the Extensor muscles of the forearm.
The fibres terminate at the upper third
of the forearm in a flat tendon, which
runs along the outer border of the
radius, beneath the extensor tendons
of the thumb; it then passes through
a groove common to it and the Ex-
tensor carpi radialis brevior, immedi-
ately behind the styloid process, and
is inserted into the base of the meta-
carpal bone of the index finger, on
its radial side.
Relations. — By its superficial sur-
face, with the Supinator longus and
fascia of the forearm; its outer side
is crossed obliquely by the extensor
tendons of the thumb; by its deep
surface, with the elbow-joint, the
Extensor carpi radialis brevior, and
back part of the wrist.
The Extensor Carpi Radialis
Brevior (m. extensor carpi radialis
brevis} (Fig. 319) is shorter, as its
name implies, and thicker than the
preceding muscle, beneath which it is
placed. It arises from the external
condyle of the humerus by a tendon
common to it and the three following
muscles ; from the external lateral
ligament of the elbow-joint, from a
strong aponeurosis which covers its
FIG. 319. — Posterior surface of the forearm. Superficial
muscles.
488 THE MUSCLES AND FASCIA
surface, and from the intermuscular septa between it and the adjacent muscles.
The fibres terminate about the middle of the forearm in a flat tendon which is
closely connected with that of the preceding muscle, and accompanies it to the
wrist, lying in the same groove on the posterior surface of the radius ; it passes
beneath the extensor tendons of the thumb, then beneath the annular ligament,
and, diverging somewhat from its fellow, is inserted into the base of the meta-
carpal bone of the middle finger, on its radial side. There is often a bursa
(bursa m. extensoris carpi radialis brevis) between a portion of the base of the
bone and the tendon.
The tendons of the two preceding muscles pass through the same compartment
of the annular ligament, and are lubricated by a single synovial membrane, but are
separated from each other by a small vertical ridge of bone as they lie in the groove
at the back of the radius.
Relations. — By its superficial surface, with the Extensor carpi radialis longior,
and with the Extensor muscles of the thumb which cross it; by its deep surface,
with the Supinator brevis, tendon of the Pronator radii teres, radius, and wrist-
joint; by its ulnar border, with the Extensor cornmunis digitorum.
10. The Posterior Radio-ulnar Region (Fig. 319).
The muscles in this region are divided for purposes of description into two
groups or layers, superficial and deep.
The Superficial Layer.
Extensor communes digitorum. Extensor carpi ulnaris.
Extensor minimi digiti. Anconeus.
The Extensor Communis Digitorum (m. extensor digitorum communis) is
situated at the back part of the forearm. It arises from the external condyle of
the humerus by the common tendon, from the deep fascia, and the intermus-
cular septa between it and the adjacent muscles. Just below the middle of
the forearm it divides into three fleshy masses, from which tendons proceed;
these pass, together with the Extensor indicis, through a separate compartment
of the annular ligament, lubricated by a synovial membrane. The tendons
then diverge, the innermost one dividing into two; and all, after passing across the
back of the hand, are inserted into the second and third phalanges of the fingers in
the following manner : the outermost tendon, accompanied by the Extensor indicis,
goes to the index finger (Figs. 319, 321, and 322); the second tendon is sometimes
connected to the first by a thin transverse band, and receives a slip from the third
tendon (Fig. 319); it goes to the middle finger; the third tendon gives off the slip
to the second (Fig. 319), and receives a very considerable part of the fourth tendon;
the fourth, or innermost tendon, divides into two parts: one goes to join the third
tendon; the other, reinforced by the Extensor minimi digiti, goes to the little
finger. Each tendon opposite the metacarpo-phalangeal articulation becomes
narrow and thickened, and gives off a thin fasciculus upon each side of the joint,
which blends with the lateral ligaments and serves as the posterior ligament;
after having passed the joint it spreads out into a broad aponeurosis, which covers
the whole of the dorsal surface of the first phalanx, being reinforced, in this
situation, by the tendons of the Interossei and Lumbricales. Opposite the first
phalangeal joint this aponeurosis divides into three slips, a middle and two
lateral: the former is inserted into the base of the second phalanx; and the two
lateral, which are continued onward along the sides of the second phalanx, unite
by their contiguous margins, and are inserted into the dorsal surface of the last
phalanx. As the tendons cross the phalangeal joints they furnish them with pos-
terior ligaments. The accessory slips or lateral vincula which join the tendon
THE POSTERIOR RADIO- ULNAR REGION 439
of the ring finger to the tendon of the little finger and the tendon of the middle
finger are constant. If the middle and little fingers are held flexed the lateral
vincula greatly limit the range of extension possible in the ring finger — a limi-
tation which interferes with a piano-player (Prof. William S. Forbes).
Relations. — By its superficial surface, with the fascia of the forearm and hand,
the posterior annular ligament, and integument; by its deep surface, with the
Supinator brevis, the Extensor muscles of the thumb and index finger, the pos-
terior interosseous vessels and nerve, the wrist-joint, carpus, metacarpus, and
phalanges; by its radial border, with the Extensor carpi radialis brevier; by its
ulnar border, with the Extensor minimi digiti and Extensor carpi ulnaris.
The Extensor Minimi Digiti (m. extensor digiti quinti proprius] is a slender
muscle placed on the inner side of the Extensor communis, with which it is gen-
erally connected. It arises from the common tendon by a thin, tendinous slip, and
from the intermuscular septa between it and the adjacent muscles. Its tendon
runs through a separate compartment in the annular ligament behind the inferior
radio-ulnar joint, then divides into two as it crosses the hand, the outermost
division being joined by the slip from the innermost tendon of the common exten-
sor. The two slips thus formed spread into a broad aponeurosis, which after
receiving a slip from the Abductor minimi digiti is inserted into the second and
third phalanges. The tendon is situated on the ulnar side of, and somewhat more
superficial than, the common extensor.
The Extensor Carpi Ulnaris is the most superficial muscle on the ulnar side of
the forearm. It arises from the external condyle of the humerus by the common
tendon; by an aponeurosis from the posterior border of the ulna in common
with the Flexor carpi ulnaris and the Flexor prof undus digitorum ; and from the
deep fascia of the forearm. This muscle terminates in a tendon which runs
through a groove behind the styloid process of the ulna, passes through a separate
compartment in the annular ligament, and is inserted into the prominent tubercle
on the ulnar side of the base of the metacarpal bone of the little finger.
Relations. — By its superficial surface, with the deep fascia of the forearm; by
its deep surface, with the ulna and the muscles of the deep layer.
The Anconeus (m. anconaeus) is a small triangular muscle placed behind and
below the elbow-joint, and appears to be a continuation of the external portion of
the Triceps. It arises by a separate tendon from the back part of the outer condyle
of the humerus, and is inserted into the side of the olecranon and upper fourth of
the posterior surface of the shaft of the ulna; its fibres diverge from their origin,
the upper ones being directed transversely, the lower obliquely inward.
Relations. — By its superficial surface, with a strong fascia derived from the
Triceps; by its deep surface, with the elbow-joint, the orbicular ligament, the
ulna, and a small portion of the Supinator brevis.
The Deep Layer (Fig. 321).
Supinator radii brevis. Extensor brevis pollicis.
Extensor ossis metacarpi pollicis. Extensor longus pollicis.
Extensor indicis.
The Supinator Radii Brevis (m. supinator] (Figs. 320 and 321) is a broad muscle,
of hollow cylindrical form, curved round the upper third of the radius. It consists of
two distinct planes of muscular fibres, between which lies the posterior interosseous
nerve (Fig. 320). The two planes arise in common: the superficial one by tendin-
ous, and the deeper by muscular, fibres from the external condyle of the humerus,
from the external lateral ligament of the elbow-joint and the orbicular ligament of
the radius; from the ridge on the ulna, which runs obliquely downward from the
490
THE MUSCLES AND FASCIAE
posterior extremity of the lesser sigmoid cavity; from the triangular depression in
front of it; and from a tendinous expansion which covers the surface of the muscle.
Int.
Cvndyle.
Coronoid
proc.
Head of
radius.
Olecranon
FIG. 320. — Supinator brevis. (From a prepa-
ration in the Museum of the Royal College of
Surgeons of England.)
EXTENSOR
CARPI ULNARIS
The superficial fibres surround the
upper part of the radius, and are in-
serted into the outer edge of the bicip-
ital tuberosity and into the oblique
line of the radius, as low down as the
insertion of the Pronator radii teres.
The upper fibres of the deeper plane
form a sling-like fasciculus, which
encircles the neck of the radius
above the tuberosity and is at-
tached to the back part of its inner
surface : the greater part of this por-
tion of the muscle is inserted into
the posterior and external surface
of the shaft, midway between the
oblique line and the head of the bone. Between the insertion of the two
planes the posterior interosseous nerve lies on the shaft of the bone (Fig. 320).
FIG. 321. — Posterior surface of the forearm. Deep muscles.
THE POSTERIOR RADIO- ULNAR REGION
491
Relations. — By its superficial surface, with the superficial Extensor and Supina-
tor muscles, and the radial vessels and nerve; by its deep surface, with the elbow-
joint, the interosseous membrane, and the radius.
The Extensor Ossis Metacarpi Pollicis (m. abductor pollicis longus) is the most
external and the largest of the deep extensor muscles: it lies immediately below
the Supinator brevis, with which it is sometimes united. It arises from the outer
part of the posterior surface of the shaft of the ulna below the insertion of the
Anconeus, from the interosseous membrane, and from the middle third of the
posterior surface of the shaft of the radius. Passing obliquely downward and
outward, it terminates in a tendon which runs through a groove on the outer side
of the styloid process of the radius, accompanied by the tendon of the Extensor
brevis pollicis, and is inserted into the base of the metacarpal bone of the thumb.
It occasionally gives off two slips near its insertion — one to the Trapezium, and the
other to blend with the origin of the Abductor pollicis.
Relations. — By its superficial surface, with the Extensor communis digitorum,
Extensor minimi digiti, and fascia of the forearm, and with the branches of the
posterior interosseous artery and nerve which cross it; by its deep surface, with
the ulna, interosseous membrane, radius, the tendons of the Extensor carpi radialis
longior and brevior, which it crosses obliquely, and, at the outer side of the wrist,
with the radial vessels; by its upper border, with the Supinator brevis; by its
lower border, with the Extensor brevis pollicis.
The Extensor Brevis Pollicis, often called the extensor primi internodii pollicis
(m. extensor pollicis brevis), the smallest muscle of this group, lies on the inner
side of the preceding. It arises from the posterior surface of the shaft of the radius,
below the Extensor ossis metacarpi
pollicis, and from the interosseous
membrane. Its direction is similar to
that of the Extensor ossis metacarpi
pollicis, its tendon passing through the
same groove on the outer side of the
styloid process, to be inserted into the
base of the first phalanx of the thumb.
Relations. — The same as those of
the Extensor ossis metacarpi pollicis.
The Extensor Longus Poilicis,
often called the extensor secundi inter-
nodii pollicis (m. extensor pollicis longus)
is much larger than the preceding
muscle, the origin of which it partly
covers in. It arises from the outer
part of the posterior surface of the
shaft of the ulna, below the origin of
the Extensor ossis metacarpi pollicis,
and from the interosseous membrane.
It terminates in a tendon which passes
through a separate compartment in
the annular ligament, lying in a nar-
row, oblique groove at the back part
of the lower end of the radius. It then crosses obliquely the tendons of the
Extensor carpi radialis longior and brevior, being separated from the other
extensor tendons of the thumb by a triangular interval, in which the radial artery
is found, and is finally inserted into the base of the last phalanx of the thumb.
Relations. — By its superficial surface, with the same parts as the Extensor ossis
metacarpi pollicis; by its deep surface, with the ulna, interosseous membrane, the
LIGAMEN
BREVIS
LIGAMENTUM
LONGUS
LIGAMENTUM BREVIS
FLEXOR SUBLIMIS
DIGITORUM
EXPANSION OF
EXTENSOR TENDON
FLEXOR PROFUNDUS
DIGITORUM
FIRST LUMBRICAL
MUSCLE
FIRST DORSAL
INTEROSSEOUS
MUSCLE
EXTENSOR INDICIS
TENDON
EXTENSOR COMMUNIS
DIGITORUM TENDON
FIG. 322. — The tendons attached to the index finger.
(Cunningham. )
492 THE MUSCLES AND FASCIA
posterior interosseous nerve, radius, the wrist, the radial vessels, and metacarpal
bone of the thumb.
The Extensor Indicis (m. extensor indicis proprius) (Figs. 319, 321, and 322) is
a narrow, elongated muscle placed on the inner side of, and parallel with, the
preceding. It arises from the posterior surface of the shaft of the ulna, below
the origin of the Extensor longus pollicis and from the interosseous membrane.
Its tendon passes with the Extensor communis digitorum through the same canal
in the annular ligament, and subsequently joins the tendon of the Extensor
communis which belongs to the index finger, opposite the lower end of the
corresponding metacarpal bone, lying to the ulnar side of the tendon from the
common extensor.
Relations. — The relations are similar to those of the preceding muscles.
Nerves. — The Supinator longus is supplied by the sixth, the Extensor carpi
radialis longior by the sixth and seventh, and the Anconeus by the seventh and
eighth cervical nerves, all through the musculo-spiral nerve; the remaining muscles
of the radial and posterior brachial region are supplied through the posterior
interosseous nerve, the Supinator brevis being supplied by the sixth cervical, the
Extensor carpi radialis brevier by the sixth and seventh cervical, and all the other
muscles by the seventh cervical.
Actions. — The muscles of the radial and posterior brachial regions, which
comprise all the extensor and supinator muscles, act upon the forearm, wrist, and
hand; they are the direct antagonists of the pronator and flexor muscles. The
Anconeus assists the Triceps in extending the forearm. The chief action of the
Supinator longus is that of a flexor of the elbow-joint, but in addition to this it
may act both as a supinator or a pronator; that is to say, if the forearm is forcibly
pronated it will act as a supinator, and bring the bones into a position midway
between supination and pronation; and vice versa, if the arm is forcibly supinated,
it will act as a pronator, and bring the bones into the same position, midway
between supination and pronation. The action of the muscle is therefore to throw
the forearm and hand into the position they naturally occcupy when placed across
the chest. The Supinator brevis is a supinator; that is to say, when the radius
has been carried across the ulna in pronation and the back of the hand is directed
forward, this muscle carries the radius back again to its normal position on the
outer side of the ulna, and the palm of the hand is again directed forward. The
Extensor carpi radialis longior extends the wrist and abducts the hand. It may
also assist in bending the elbow-joint; at all events, it serves to fix or steady this
articulation. The Extensor carpi radialis brevior assists the Extensor carpi
radialis longior in extending the wrist, and may also act slightly as an abductor of
the hand. The Extensor carpi ulnaris helps to extend the hand, but when acting
alone inclines it toward the ulnar side; by its continued action it extends the
elbow-joint. The Extensor communis digitorum extends the phalanges, then the
wrist, and finally the elbow. It acts principally on the proximal phalanges, the
middle and terminal phalanges being extended by the Interossei and Lumbri-
cales. It has also a tendency to separate the fingers as it extends them. The
Extensor minimi digiti extends similarly the little finger, and by its continued
action it assists in extending the wrist. It is owing to this muscle that the little
finger can be extended or pointed whilst the others are flexed. The chief action of
the Extensor ossis metacarpi pollicis is to carry the thumb outward and backward
from the palm of the hand, and hence it has been called the abductor pollicis longus.
By its continued action it helps to extend and abduct the wrist. The Extensor
brevis pollicis extends the proximal phalanx of the thumb. By its continued
action it helps to extend and abduct the wrist. The Extensor longus pollicis
extends the terminal phalanx of the thumb. By its continued action it helps to
extend and abduct the wrist. The Extensor indicis extends the index finger, and
OF THE HAND
493
by its continued action assists in extending the wrist. It is owing to this muscle
that the index finger can be extended or pointed while the others are flexed.
Surgical Anatomy.— The tendons of the extensor muscles of the thumb are liable to become
strained and their sheaths inflamed after excessive exercise, producing a sausage-shaped swell-
ing along the course of the tendon, and giving a peculiar creaking sensation to the finger when
the muscle acts. In consequence of its often being caused by such movements as wringing
clothes, it is known as washerwoman's sprain. In piano-players the slips which join the ten-
dons of the Extensor communis digitorum may limit freedom of motion in individual fingers.
" When the middle finger and little finger of the hand are brought down by the flexor muscles,
and their balls are held down firmly against the keys of a musical instrument, as in perform-
ing on a piano for the purpose of producing continuous sounds, and when at the same time ,
it is necessary to extend and then to flex the ring-finger in order to produce accompanying
sounds, it will be found that in the still-flexed position of the middle and little fingers, the
rim/ fitiyer can be but very slightly extended. Its complete extension, without operative inter-
ference, can only be brought about by long-continued exertion in practice, when elongation
of certain accessory, but restricting, tendons is made by nutritive growth."1 If there is much
limitation division of the hindering slips is proper. This was suggested by Prof. William S.
Forbes in 1857.
IV. MUSCLES AND FASCI-ffi OF THE HAND.
The muscles of the hand are subdivided into three groups: 1. Those of the
thumb, which occupy the radial side and produce the thenar eminence. 2. Those
of the little finger, which occupy the ulnar side and give rise to the hypothenar
eminence. 3. Those in the middle of the palm and within the interosseous spaces.
Dissection (Fig. 311). — Make a transverse incision across the front of the wrist, and a
second across the heads of the metacarpal bones: connect the two by a vertical incision in the
middle line, and continue it through the centre of the middle finger. The anterior and poste-
rior annular ligaments and the palmar fascia should then be dissected.
ANTERIOR
ANNULAR
LIGAMENT,
FLEXOR LONGUS POLLICIS.
FLEXOR CARPI RADIALIS.
MUSCLES OF THUMB
1st Metacarpal
EXT. PRIM
INTERNOD.
POLL.
EXT. SEC.
INTERNOO.
POLL.
Trapezium^
Radial vessels.
EXT. CARP. RAD. LONG
Trupezoid.
EXTENSOR CARPI RADIALIS
DREVIOR.
,Median nerve.
JJlnar vessels.
ALMARIS BREVIS.
MUSCLES OF
LITTLE
FINGER.
EXT. CARPI
ULNARIS.
XTENSOR
INIMI
DIGIT).
EXTENSOR
COMMUNIS
DIGITORUM.
EXTENSOR INDICIS.
On magnum.
FIG. 323. — Transverse section through the carpus, showing the relative positions of the tendons, vessels,
and nerves. (Henle.)
The Ligamentum Carpi Volare is a thickening of the deep fascia of the forearm
(fascia antibrachii) by deep fibres just above the wrist (Fig. 328). It covers the
flexor muscles and joins the anterior annular ligament.
The Anterior Annular Ligament (ligamentum carpi transversum) (Fig. 323) is a
strong, fibrous band which arches over the carpus, converting the deep groove
on the front of the carpal bones into a canal, beneath which pass the flexor
tendons of the fingers. It is attached, internally, to the pisiform bone and
1 Prof. William S. Forbes in the Philadelphia Medical Journal, January 15, 1898.
494
THE MUSCLES AND FASCIAE
the hook of the unciform bone (eminentia carpi ulnaris), and externally to the
tuberosity of the scaphoid and to the inner part of the anterior surface and
the ridge of the trapezium (eminentia carpi radialis). It is continuous, above,
with the deep fascia of the forearm, of which it may be regarded as a thickened
portion, and, below, with the palmar fascia. It is crossed by the ulnar vessels and
nerve and the cutaneous branches of the median and ulnar nerves. At its outer
extremity is the tendon of the Flexor carpi radialis, which lies in the groove on the
trapezium between the attachments of
the annular ligaments to the bone. It
has inserted into its anterior surface a
part of the tendon of the Palmaris longus
and part of the tendon of the Flexor
carpi ulnaris, and has arising from it,
below, the small muscles of the thumb
and little finger. Beneath it pass the
tendons of the Flexor sublimis and Pro-
fundus digitorum, the Flexor longus
pollicis, and the median nerve.
The Synovial Membranes of the Flexor
Tendons at the Wrist. — There are two
vaginal synovial membranes which en-
close all the tendons as they pass be-
neath this ligament — one for the Flexor
sublimis and Profundus digitorum, the
other for the Flexor longus pollicis.
They extend up into the forearm for
about an inch above the annular liga-
ment, and downward about half-way
along the metacarpal bone, where they
terminate in a blind diverticulum around
each pair of tendons, with the exception
of that of the thumb and those of the
little finger — in each of these two digits the diverticulum is continued on, and
communicates with the synovial sheath of the tendons in the fingers. In the other
three fingers the synovial sheath of the tendons begins as a blind pouch without
communication with the large synovial sac (Fig. 324).
Surgical Anatomy. — This arrangement of the synovial sheaths explains the fact that thecal
abscess in the thumb and little finger is liable to be followed by abscesses in the forearm, from
extension of the inflammation along the continuous synovial sheaths. Tuberculous inflamma-
tion is apt to occur in this situation, constituting compound palmar ganglion ; it presents an hour-
glass outline, with a swelling in front of the wrist and in the palm of the hand, and a constriction
corresponding to the annular ligament between the two. The fluid can be forced from the one
swelling to the other under the ligament.
Bursae about the Hand and Wrist. — Bursse usually exist between the distal
extremities of the metacarpal bones (bursae intermetacarpophalangeae), and a sub-
cutaneous bursa often exists over the dorsal surface of the head of the fifth
metacarpal bone. Subcutaneous digital dorsal bursae occur "almost constantly
in the first finger-joints (between the first and second phalanx), occasionally in
the second joint of the second and fourth fingers"1 (bursae subcutaneae digitorum
dorsales). A bursa exists between the tendon of the Extensor carpi radialis brevior
and the base of the third metacarpal bone; another between the Flexor carpi
ulnaris and the pisiform bone ; another between the Flexor carpi radialis and the
base of the second metacarpal bone.
1 Hand Atlas of Human Anatomy. By Werner Spalteholz. Translated and edited by Lewellys F. Barker.
FIG. 324. — Diagram showing the arrangement of the
synovial sheaths of the palm and fingers.
OF THE HAND 495
The Posterior Annular Ligament (I ig amentum carpi dorsale) is a strong fibrous
band extending obliquely downward and inward across the back of the wrist, and
consisting of the deep fascia of the back of the forearm, strengthened by the
addition of some transverse fibres. It binds down the extensor tendons in their
passage to the fingers, being attached, internally, to the styloid process of the ulna,
the cuneiform and pisiform bones; externally, to the margin of the radius; and, in
its passage across the wrist, to the elevated ridges on the posterior surface of the
radius. It presents six compartments for the passage of tendons, each of which is
lined by a separate synovial membrane
(Fig. 325). These are, from without
inward: 1. On the outer side of the
styloid process, for the tendons of the
Extensor ossis metacarpi and Extensor
brevis pollicis. 2. Behind the styloid
process, for the tendons of the Ex-
tensor carpi radialis longior and bre-
vior. 3. About the middle of the
posterior surface of the radius, for the
tendon of the Extensor longus pollicis.
4. To the inner side of the latter, for
the tendons of the Extensor communis
... . _ . ,. . _ FIG. 325. — Transverse section through the wrist, show-
dlgltoriim and Extensor mdlClS. 5. ing the annular ligaments and the canals for the passage
Opposite the interval between the
radius and ulna, for the Extensor minimi digiti. 6. Grooving the back of the
ulna, for the tendon of the Extensor carpi ulnaris. The synovial membranes
lining these sheaths are usually very extensive, reaching from above the annular
ligament down upon the tendons for a variable distance on the back of the
hand.
The Deep Palmar Fascia (aponeurosis palmaris). — The deep palmar fascia
(Fig. 326) forms a common sheath which invests the muscles of the hand.
It consists of a central and two lateral portions.
The Central Portion occupies the middle of the palm, is triangular in shape, of
great strength and thickness, and binds down the tendons and protects the vessels
and nerves in this situation. It is narrow above, where it is attached to the lower
margin of the annular ligament, and receives the expanded tendon of the Pal-
maris longus muscle. Below, it is broad and expanded, and divides into four
slips for the four fingers. Each slip gives off superficial fibres, which are inserted
into the skin of the palm and finger, those to the palm joining the skin at the
furrow corresponding to the metacarpo-phalangeal articulation, and those to the
fingers passing into the skin at the transverse fold at the base of the fingers. The
deeper part of each slip subdivides into two processes, which are inserted into the
lateral margins of the anterior (glenoid) ligament of the metacarpo-phalangeal
joint. From the sides of these processes offsets are sent backward, to be attached
to the borders of the lateral surfaces of the metacarpal bones at their distal extrem-
ities. By this arrangement short channels are formed on the front of the lower
ends of the metacarpal bones, through which the flexor tendons pass. Dr. W. W.
Keen describes a fifth slip as frequently found passing to the thumb. The inter-
vals left in the fascia between the four fibrous slips transmit the digital vessels
•and nerves and the tendons of the Lumbricales. At the points of division of the
palmar fascia into the slips above mentioned numerous strong, transverse fibres
bind the separate processes together. The palmar fascia is intimately adherent
to the integument by dense fibro-areolar tissue, forming the superficial palmar
fascia, and gives origin by its inner margin to the Palmaris brevis: it covers the
superficial palmar arch, the tendons of the flexor muscles, and the branches of
496
THE MUSCLES AND FASCIA
the median and ulnar nerves, and on each side it gives off a vertical septum, which
is continuous with the interosseous aponeurosis and separates the lateral from
the middle palmar group of muscles.
The Lateral Portions of the Palmar Fascia are thin, fibrous layers, which cover,
on the radial side, the muscles of the ball of the thumb, and, on the ulnar side, the
muscles of the little finger; they are continuous with the dorsal fascia, and in the
palm with the central portion of the palmar fascia.
Digital artery
Digital nerves.
FIG. 326. —Palmar fascia. (From a preparation in the Museum of the Royal College of Surgeons of England.)
The Superficial Transverse Ligament of the Fingers is a thin, fibrous band which
stretches across the roots of the four fingers, and is closely attached to the skin
of the clefts, and internally to the fifth metacarpal bone, forming a sort of rudi-
mentary web. Beneath it the digital vessels and nerves pass onward to their
destination.
Surgical Anatomy. — The palmar fascia is liable to undergo contraction, producing a very
inconvenient deformity known as Dupuytreris contraction. The ring and little fingers are most
frequently implicated, but the middle, index, and the thumb may be involved. The proximal
phalanx is drawn down and cannot be straightened, and the two distal phalanges become simi-
larly flexed as the disease advances.
THE RADIAL REGION
11. The Radial Region (Figs. 327, 328).
497
Abductor pollicis.
Opponens pollicis.
Adductor transversus pollicis.
Flexor brevis pollicis.
Adductor obliquus pollicis.
The Abductor Pollicis (m. abductor pollicis brevis} (Fig. 328) is a thin, flat
muscle, placed immediately beneath the integument. It arises from the anterior
annular ligament, the tuberosity of the scaphoid, and the ridge of the trapezium,
FIG. 327. — Adductor pollicis, Opponens pollicis, and Pronator quadratus. (Testut.)
frequently by two distinct slips; and, passing outward and downward, is inserted
by a thin, flat tendon into the radial side of the base of the first phalanx of the
thumb, sending a slip to join the tendon of the Extensor longus pollicis.
32
498
THE MUSCLES AND FASCIAE
Relations. — By its superficial surface, with the palmar fascia and superficial
volae artery, which frequently perforates it. By its deep surface, with the Opponens
pollicis, from which it is separated by a thin aponeurosis. Its inner border is
separated from the Flexor brevis pollicis by a narrow cellular interval.
FIG. 328. — Muscles of the left hand. Palmar surface.
The Opponens Pollicis (Figs. 327 and 328), often called the flexor ossis meta-
carpi pollicis, is a small, triangular muscle, placed beneath the preceding. It arises
from the palmar surface of the ridge on the trapezium and from the annular
ligament, passes downward and outward, and is inserted into the whole length of
the metacarpal bone of the thumb on its radial side.
THE RADIAL REGION 499
Relations. — By its superficial surface, with the Abductor and Flexor brevis
pollicis. By its deep surface, with the trapezio-metacarpal articulation. By its
'inner border, with the Adductor obliquus pollicis.
The Flexor Brevis Pollicis (m. flexor pollicis brevis) (Fig. 328) consists of two
portions, outer and inner. The outer and more superficial portion arises from the
outer two-thirds of the lower border of the anterior annular ligament, and passes
along the outer side of the tendon of the Flexor longus pollicis; and, becoming
tendinous, has a sesamoid bone developed in its tendon, and is inserted into- the
outer side of the base of the first phalanx of the thumb. The inner and deeper
portion of the muscle is very small, and arises from the ulnar side of the first
metacarpal bone beneath the Adductor obliquus pollicis, and is inserted into the
inner side of the base of the first phalanx with this muscle.
Relations. — By its superficial surface, with the palmar fascia. By its deep sur-
face, with the tendon of the Flexor longus pollicis. By its external surface, with
the Opponens pollicis. Behind, with the Adductor obliquus pollicis.
The Adductor Obliquus Pollicis (m. adductor pollicis) (Figs. 327 and 328)
arises by several slips from the os magnum, the bases of the second and third
metacarpal bones, the anterior carpal ligaments, and the sheath of the tendon
of the Flexor carpi radialis. From this origin the greater number of fibres
pass obliquely downward and converge to a tendon, which, uniting with the
tendons of the deeper portion of the Flexor brevis pollicis and the Adductor
transversus, is inserted into the inner side of the base of the first phalanx of the
thumb, a sesamoid bone being developed in the tendon of insertion. A consid-
erable fasciculus, however, passes more obliquely outward beneath the tendon
of the long flexor to join the superficial portion of the short flexor and the
Abductor pollicis.1
Relations. — By its superficial surface, with the Flexor longus pollicis and the
outer head of the Flexor brevis pollicis. Its deep surface is in relation with the
deep palmar arch, which passes between the two adductors.
The Adductor Transversus Pollicis (Figs. 327 and 328) is the most deeply
seated of this group of muscles. It is of a triangular form, arising, by its broad
base, from the lower two-thirds of the metacarpal bone of the middle finger on
its palmar surface; the fibres, proceeding outward, converge to be inserted, with
the inner part of the Flexor brevis pollicis, and the Adductor obliquus pollicis,
into the ulnar side of the base of the first phalanx of the thumb. From the
common tendon of insertion a slip is prolonged to the Extensor longus pollicis.
The name adductor pollicis is frequently used to mean both of the adductors
(Figs. .327 and 328).
Relations. — By its superficial surface, with the Adductor obliquus pollicis, the
tendons of the Flexor profundus, and the Lumbricales. Its deep surface covers
the first two interosseous spaces, from which it is separated by a strong aponeu-
rosis.
Three of these muscles of the thumb, the Abductor, the Adductor transversus,
and the Flexor brevis pollicis, at their insertions give off fibrous expansions which
join the tendon of the Extensor longus pollicis. This permits of flexion of the
proximal phalanx and extension of the terminal phalanx at the same time. These
expansions, originally figured by Albinus, have been more recently described by
M. Duchenne.2
Nerves. — The Abductor, Opponens, and outer head of the Flexor brevis pollicis
are supplied by the sixth cervical through the median nerve; the inner head of the
Flexor brevis, and the Adductors, by the eighth cervical through the ulnar nerve.
1 This muscle is described by some as the deep portion of the Flexor brevis pollicis.
2 Physiologic des Mouvements.
500 THE MUSCLES AND FASCIA
Actions. — The actions of the muscles of the thumb are almost sufficiently indi-
cated by their names. This segment of the hand is provided with three extensors
— an extensor of the metacarpal bone, an extensor of the first, and an extensor of
the second phalanx; these occupy the dorsal surface of the forearm and hand.
There are also three flexors on the palmar surface — a flexor of the metacarpal
bone, a flexor of the proximal, and a flexor of the terminal phalanx; there is also
an Abductor and two Adductors. The Abductor pollicis moves the metacarpal
bone of the thumb outward; that is, away from the index finger. The Flexor
ossis metacarpi pollicis flexes the metacarpal bone — that is, draws it inward over
the palm — and at the same time rotates the bone, so as to turn the ball of the
thumb toward the fingers, thus producing the movement of opposition. The
Flexor brevis pollicis flexes and adducts the proximal phalanx of the thumb. The
Adductores pollicis move the metacarpal bone of the thumb inward; that is,
toward the index finger. These muscles give to the thumb its extensive range of
motion. It will be noticed, however, that in consequence of the position of the
first metacarpal bone, these movements differ from the corresponding movements
of the metacarpal bones of the other fingers. Thus extension of the thumb more
nearly corresponds to the motion of abduction in the other fingers, and flexion to
adduction.
12. The Ulnar Region (Fig. 328).
Palmaris brevis. Flexor brevis minimi digiti.
Abductor minimi digiti. Opponens minimi digiti.
The Palmaris Brevis is a thin quadrilateral muscle placed beneath the integu-
ment on the ulnar side of the hand. It arises by tendinous fasciculi from the
anterior annular ligament and palmar fascia; the fleshy fibres pass inward, to be
inserted into the skin on the inner border of the palm of the hand.
Relations. — By its superficial surface, with the integument, to which it is inti-
mately adherent, especially by its inner extremity; by its deep surface, with the
inner portion of the palmar fascia, which separates it from the ulnar vessels and
nerve, and from the muscles of the ulnar side of the hand.
The Abductor Minimi Digiti (m. abductor digiti quinti) is situated on the ulnar
border of the palm of the hand. It arises from the pisiform bone and from the
tendon of the Flexor carpi ulnaris, and terminates in a flat tendon, which divides
into two slips; one is inserted into the ulnar side of the base of the first phalanx
of the little finger. The other slip is inserted into the ulnar border of the aponeu-
rosis of the Extensor minimi digiti.
Relations. — By its superficial surface, with the inner portion of the palmar fascia
and the Palmaris brevis ; by its deep surface, with the Opponens minimi digiti ;
by its outer border, with the Flexor brevis minimi digiti.
The Flexor Brevis Minimi Digiti (m. fiexor digiti quinti brevis) lies on the same
plane as the preceding muscle, on its radial side. It arises from the convex aspect
of the hook of the unciform bone and anterior surface of the annular ligament,
and is inserted into the inner side of the base of the first phalanx of the little finger.
It is separated from the Abductor at its origin by the deep branches of the ulnar
artery and nerve. This muscle is sometimes wanting; the Abductor is then,
usually, of large size.
Relations. — By its superficial surface, with the internal portion of the palmar
fascia and the Palmaris brevis; by its deep surface, with the Opponens. The deep
branch of the ulnar artery and the corresponding branch of the ulnar nerve pass
between the Abductor and Flexor brevis minimi digiti muscles.
The Opponens Minimi Digiti (m. opponens digiti quinti). — This muscle is
sometimes called the flexor ossis metacarpi (Fig. 318), is of a triangular form, and
placed immediately beneath the preceding muscles. It arises from the convexity
THE MIDDLE PALMAR REGION
501
of the hook of the unciform bone and the contiguous portion of the anterior
annular ligament; its fibres pass downward and inward, to be inserted into the
whole length of the metacarpal bone of the little finger, along its ulnar margin.
Relations. — By its superficial surface, with the Flexor brevis and Abductor
minimi digiti; by its deep surface, with the Interossei muscles in the fourth meta-
carpal space, the metacarpal bone, and the Flexor tendons of the little finger.
Nerves. — All the muscles of this group are supplied by the eighth cervical nerve
through the ulnar nerve.
Actions. — The Abductor minimi digiti abducts the little finger from the middle
line of the hand. It corresponds to a dorsal interosseous muscle. It also assists
in flexing the proximal phalanx and extending the second and third phalanges.
The Flexor brevis minimi digiti abducts the little finger from the middle line of
the hand. It also assists in flexing the proximal phalanx. The Opponens minimi
digiti draws forward the fifth metacarpal bone, so as to deepen the hollow of the
palm. The Palmaris brevis corrugates the skin on the inner side of the palm of
the hand and probably serves to protect the ulnar nerve and artery from damage
by the pressure of grasping a hard object.
13. The Middle Palmar Region.
Lumbricales. Interossei dorsales.
Interossei palmares.
The Lumbricales (Fig. 328) are four small fleshy fasciculi, accessories to the
deep Flexor muscle. They arise from the tendons of the deep Flexor: the first and
second, from the radial side and palmar surface of the tendons of the index and
middle fingers respectively; the third, from the contiguous sides of the tendons of
the middle and ring fingers; and the fourth, from the contiguous sides of the
tendons of the ring and little fingers. They pass to the radial side of the corre-
sponding fingers and opposite the metacarpo-phalangeal articulation each tendon
is inserted into the tendinous expansion of the Extensor communis digitorum,
covering the dorsal aspect of each finger.
The Interossei Muscles (Figs. 329 and 330) are so named from occupying
the intervals between the metacarpal bones, and are divided into two sets, dorsal
and palmar.
The Dorsal interossei (mm. interossei dorsales} are four in number, larger than the
palmar, and occupy the intervals between the metacarpal bones. They are bipen-
niform muscles, arising by two heads from the adjacent sides of the metacarpal
bones, but more extensively from the metacarpal bone of the finger into which the
muscle is inserted. They are inserted into the bases of the first phalanges and into
the aponeurosis of the common Extensor tendon. Between the double origin of
each of these muscles is a narrow triangular interval, through the first of which
passes the radial artery; through each of the other three passes a perforating
branch from the deep palmar arch.
The First dorsal interosseous muscle or Abductor indicis is larger than the
others. It is flat, triangular in form, and arises by two heads, separated by a
fibrous arch, for the passage of the radial artery from the dorsum to the palm of
the hand. The outer head arises from the upper half of the ulnar border of the
first metacarpal bone; the inner head, from almost the entire length of the radial
border of the second metacarpal bone; the tendon is inserted into the radial side
of the index finger. The second and third dorsal interossei are inserted into the
middle finger, the former into its radial, the latter into its ulnar side. The fourth
is inserted into the ulnar side of the ring finger.
The Palmar interossei (mm. interossei volares}, three in number, are smaller than
the Dorsal, and placed upon the palmar surface of the metacarpal bones, rather
502
THE MUSCLES AND FASCIAE
than between them. Each muscle arises from the entire length of the meta-
carpal bone of one finger, and is inserted into the side of the base of the first
phalanx and aponeurotic expansion of the common extensor tendon of the same
finger. The first arises from the ulnar side of the second metacarpal bone, and
is inserted into the same side of the first phalanx of the index finger. The second
arises from the radial side of the fourth metacarpal bone, and is inserted into the
FIG. 329.— The Dorsal interossei of left hand.
FIG. 330. — The Palmar interossei of left hand.
same side of the ring finger. The third arises from the radial side of the fifth
metacarpal bone, and is inserted into the same side of the little finger. From
this account it may be seen that each finger is provided with two Interosseous
muscles, with the exception of the little finger, in which the Abductor muscle
takes the place of one of the pair.
Nerves.— The two outer Lumbricales are supplied by the sixth cervical nerve,
through the third and fourth digital branches of the median nerve: the two inner
Lumbricales and all the Interossei are supplied by the eighth cervical nerve,
through the deep palmar branch of the ulnar nerve. Brooks states that the third
lumbrical received a twig from the median in twelve out of twenty-one cases.
Actions. — The Palmar interossei muscles adduct the fingers to an imaginary
line drawn longitudinally through the centre of the middle finger; and the Dorsal
interossei abduct the fingers from that line. In addition to this, the Interossei, in
conjunction with the Lumbricales, flex the first phalanges at the metacarpo-phalan-
geal joints, and extend the second and third phalanges in consequence of their
insertion into the expansion of .the extensor tendons. The Extensor communis
digitorum is believed to act almost entirely on the, first phalanges.
SURFACE FORM OF THE UPPER EXTREMITY.
The Pectoralis major muscle largely influences surface form and conceals a considerable part
oi the thoracic wall in front. Its sternal origin presents a festooned border which bounds and
determines the width of the sternal furrow. Its clavicular origin is somewhat depressed and flat-
tened, and between the two portions of the muscle is often an oblique depression which differen-
tiates the one from the other. The outer margin of the muscle is generally well marked above,
and bounds the infradavicular fossa, a triangular interval which separates the Pectoralis major
SURFACE FORM OF THE UPPER EXTREMITY 593
from the Deltoid. It gradually becomes less marked as it approaches the tendon of insertion,
and becomes more closely blended with the Deltoid muscle. The lower border of the Pectoralis
m:i jor forms the rounded anterior axillary fold, and corresponds with the direction of the fifth rib.
The Pectoralis minor muscle influences surface form. When the arm is raised its lowest slip
of origin produces a local fulness just below the border of the anterior fold of the axilla, and so
serves to break the sharp line of the lower border of the Pectoralis major muscle, which is pro-
duced when the arm is in this position. The origin of the Serratus magnus muscle produces a
very characteristic surface marking. When the arm is raised from the side in a well-developed
subject, the five or six lower serrations are plainly discernible, forming a zigzag line, caused by
the series of digitations, which diminish in size from above downward, and have their apices
arranged in the form of a curve. When the arm is lying by the side, the first serration to
appear, at the lower margin of the Pectoralis major, is the one attached to the fifth rib. The
Deltoid muscle, with the prominence of the upper extremity of the humerus, produces the
rounded outline of the shoulder. It is rounder and fuller in front than behind, where it presents
a somewhat flattened form. Its anterior border, above, presents a rounded, slightly curved
eminence, which bounds externally the infraclavicular fossa; below, it is closely united with the
Pectoralis major. Its posterior border is thin, flattened, and scarcely marked above; below, it
is thicker and more prominent. When the muscle is in action, the middle portion becomes
irregular, presenting alternate longitudinal elevations and depressions, the elevations correspond-
ing to the fleshy portions, the depressions to the tendinous intersections of the muscle. The
insertion of the Deltoid is marked by a depression on the outer side of the middle of the arm.
Of the scapular muscles, the only one which materially influences surface form is the Teres
major, which assists the Latissimus dorsi in forming the thick, rounded fold of the posterior
boundary of the axilla. When the arm is raised, the Coraco-brachialis reveals itself as a long,
narrow elevation which emerges 'from under cover of the anterior fold of the axilla and runs
downward, internal to the shaft of the humerus. When the arm is hanging by the side, its
front and inner part presents the prominence of the Biceps, bounded on either side by an inter-
muscular depression. This muscle determines the contour of the front of the arm, and extends
from the anterior margin of the axilla to the bend of the elbow. Its upper tendons are con-
cealed by the Pectoralis major and the Deltoid, and its lower tendon sinks into the space at the
bend of the elbow. When the muscle is in a state of complete contraction — that is to say,
when the forearm has been flexed and supinated — it presents a rounded convex form, bulged
out laterally, and its length is diminished.- On each side of the Biceps, at the lower part of
the arm, the Brachialis anticus is discernible. On the outer side it forms a narrow eminence
which extends some distance up the arm along the border of the Biceps. On the inner side it
shows itself only as a little fulness just above the elbow. On the back of the arm the long head
of the Triceps may be seen as a longitudinal eminence emerging from under cover of the Deltoid,
and gradually merging into the longitudinal flattened plane of the tendon of the muscle on the
lower part of the back of the arm. The tendon of insertion of the muscle extends about half-
way up the back of the arm, where it forms an elongated flattened plane when the muscle is in
action. Under similar conditions the surface forms produced by the three heads of the muscle
are well seen. On the anterior aspect of the elbow are to be seen two muscular elevations,
one on each side, separated above and converging below so as to form a triangular space.
Of these, the inner elevation, consisting of the flexors and pronator, forms the prominence
along the inner side and front of the forearm. It is a fusiform mass, pointed above at the
internal condyle and gradually tapering off below. The Pronator radii teres, the innermost
muscle of the group, forms the boundary of the triangular space at the bend of the elbow. It
is shorter, less prominent, and more oblique than the outer boundary. The most prominent
part of the eminence is produced by the Flexor carpi radialis, the muscle next in order on the
inner side of the preceding one. It forms a rounded prominence above, and can be traced
downward to its tendon, which can be felt lying on the front of the wrist, nearer to the radial
than to the ulnar border, and to the inner side of the radial artery. The Palmaris longus pre-
sents no surface marking above, but below is the most prominent tendon on the front of the
wrist, standing out, when the muscle is in action, as a sharp, tense cord beneath the skin. The
Flexor sublimis digitorum does not directly influence surface form. The position of its four
tendons on the front of the lower part of the forearm is indicated by an elongated depression
between the tendons of the Palmaris longus and the Flexor carpi ulnaris. The Flexor carpi
ulnaris occupies a small part of the posterior surface of the forearm, and is separated from the
extensor and supinator group, which occupies the greater part of this surface, by the ulnar
furrow, produced by the subcutaneous posterior border of the ulna. Its tendon can be perceived
along the ulnar border of the front of the forearm, and is most marked when the hand is flexed
and adducted. The deep muscles of the front of the forearm have no direct influence on sur-
face form. The external group of muscles of the forearm, consisting of the extensors and supi-
nators, occupy the outer and a considerable portion of the posterior surface of this region. It
has a fusiform outline, which is altogether on a higher level than the pronato-flexor group. Its
apex emerges from between the Triceps and Brachialis anticus muscles some distance above the
504 THE MUSCLES AND FASCIA
elbow-joint, and acquires its greatest breadth opposite the external condyle, and thence gradually
shades off into a flattened surface. About the middle of the forearm it divides into two
longitudinal eminences which diverge from each other, leaving a triangular interval between
them. The outer of these two groups of muscles consists of the Supinator longus and the
Extensor carpi radialis longior et brevior, which form a longitudinal eminence descending from
the external condylar ridge in the direction of the styloid process of the radius. The other and
more posterior group consists of the Extensor communis digitorum, the Extensor minimi digiti,
and the Extensor carpi ulnaris. It commences above as a tapering form at the external con-
dyle of the humerus, and is separated behind at its upper part from the Anconeus by a well-
marked furrow, and below, from the pronato-flexor mass, by the ulnar furrow. In the triangular
interval left between these two groups the extensors of the thumb and index finger are seen.
The only two muscles of this region which require special mention as independently influencing
surface form are the Supinator longus and the Anconeus. The inner border of the Supinator
longus forms the outer boundary of the triangular space at the bend of the elbow. It com-
mences as a rounded border above the condyle, and is longer, less oblique, and more prominent
than the inner boundary. Lower down, the muscle forms a full fleshy mass on the outer side of
the upper part of the forearm, and below tapers into a tendon, which may be traced down to
the styloid process of the radius. The Anconeus presents a well-marked and characteristic
surface form in the shape of a triangular, slightly elevated surface, immediately external to the
subcutaneous posterior surface of the olecranon, and differentiated from the common extensor
group by a well-marked oblique longitudinal depression. The upper angle of the triangle corre-
sponds to the external condyle, and is marked by a depression or dimple in this situation. In
the interval caused by the divergence from each other of the two groups of muscles into which
the extensor and supinator group is divided at the lower part of the forearm an oblique elongated
eminence is seen, caused by the emergence of two of the extensors of the thumb from their
deep origin at the back of the forearm. This eminence, full above and becoming flattened
out and partially subdivided below, runs downward and outward over the back and outer sur-
face of the radius to the outer side of the wrist-joint, where it forms a ridge, especially marked
when the thumb is extended, which passes onward to the posterior aspect of the thumb. The
tendons of most of the extensor muscles are to be seen and felt at the level of the wrist-joint.
Most externally are the tendons of the Extensor ossis metacarpi pollicis and the Extensor brevis
pollicis, forming a vertical ridge over the outer side of the joint from the styloid process of the
radius to the thumb. Internal to this is the oblique-ridge produced by the tendon of the Exten-
sor longus pollicis, very noticeable when the muscle is in action. The Extensor carpi radialis
longior is scarcely to be felt, but the Extensor carpi radialis brevior can be distinctly perceived
as a vertical ridge emerging from under the inner border of the tendon of the Extensor longus
pollicis, when the hand is forcibly extended at the wrist. Internal to this, again, can be felt
the tendons of the Extensor indicis, Extensor communis digitorum, and Extensor minimi digiti;
the latter tendon being separated from those of the common extensor by a slight furrow. The
muscles of the hand are principally concerned, as far as regards surface-form, in producing
the thenar and hypothenar eminences, and individually are not to be distinguished, on the sur-
face, from each other. The Adductor transversus pollicis is, however, an exception to this;
its anterior border gives rise to a ridge across the web of skin connecting the thumb to the rest
of the hand. The thenar eminence is much larger and rounder than the hypothenar one, which
presents a longer and narrower eminence along the ulnar side of the hand. When the Palmaris
brevis is in action it produces a wrinkling of the skin over the hypothenar eminence, and a deep
dimple on the ulnar border of the hand. The anterior extremities of the Lumbrical muscles
help to produce the soft eminences just behind the clefts of the fingers, separated from each
other by depressions corresponding to the flexor tendons in their sheaths. Between the thenar
and hypothenar eminences, at the wrist-joint, is a slight groove or depression, widening out as
it approaches the fingers; beneath this we have the strong central part of the palmar fascia.
Here we have some furrows, which are pretty constant in their arrangement, and bear some
resemblance to the letter M. One of these furrows passes obliquely outward from the groove
between the thenar and hypothenar regions near the wrist to the head of the metacarpal bone
of the index finger. A second passes inward, with a slight inclination upward, from the ter-
mination of the first to the ulnar side of the hand. A third runs nearly parallel with the second
and about three-quarters of an inch below it. Lastly, crossing these two latter furrows, is an
oblique furrow parallel with the first. The skin of the palm of the hand differs considerably
from that of the forearm. At the wrist it suddenly becomes hard and dense, and covered with
a thick layer of cuticle. The skin in the thenar region presents these characteristics less than
elsewhere. In spite of this hardness and density, the skin of the palm is exceedingly sensitive
and very vascular. It is destitute of hair, and no sebaceous follicles have been found in this
region. Over the fingers the skin again becomes thinner, especially at the flexures of the joints,
and over the terminal phalanges it is thrown into numerous ridges in consequence of the arrange-
ment of the papilla? in it. These ridges form, in different individuals, distinctive and permanent
patterns, which may be used for purposes of identification. The superficial fascia in the palm
SURGICAL ANATOMY OF THE UPPER EXTREMITY 505
is made up of dense fibro-fatty tissue. This tissue binds down the skin so firmly to the deep
palmar fascia that verv little movement is permitted between the two. On the back of the hand
the Dorsal interossei produce elongated swellings between the metacarpal bones. The first
dorsal interosseous (Abductor indicis), when the thumb is closely adducted to the hand, forms
a prominent fusiform bulging; the other interossei are not so marked.
SURGICAL ANATOMY OF THE UPPER EXTREMITY.
The student, having completed the dissection of the muscles of the upper extremity, should
consider the effects likely to be produced by the action of the various muscles in fracture of the
bones.
In considering the actions of the various muscles upon fractures of the upper extremity, the
most common forms of injury have been selected both for illustration and description.
Fracture of the middle of the clavicle (Fig. 331) is always attended with considerable dis-
placement; the inner end of the outer fragment is displaced inward and backward, while the
outer end of the same fragment is rotated forward. The whole outer fragment is somewhat
depressed. The deformity is described by saying that the shoulder goes downward, forward,
and inward.
The displacement is produced as follows: inward, by the muscles passing from the chest to
the outer fragment of the clavicle, to the scapula, and to the-humerus — viz., the Subclavius and
the Pectoralis minor, and, to a less extent, the Pectoralis major and the Latissimus dorsi; back-
ward, in consequence of the rotation of the outer fragment. The Serratus magnus causes the
scapula to rotate on the wall of the chest; this carries the acromion and outer end of the outer
fragment of the clavicle forward and causes the piece of bone to rotate round a vertical axis
through its centre, and so carries the inner end of the outer portion backward. The depression
of the whole outer fragment is produced by the weight
of the arm and by the contraction of the Deltoid. The
outer end of the inner fragment appears to be elevated,
the skin being drawn tensely over it ; this is owing to
the depression of the outer fragment, as the inner frag-
ment is usually kept fixed by the costo-clavicular liga-
ment and by the antagonism between the Sternomastoid
and Pectoralis major muscles. But it may be raised by
an unusually strong Sterno-mastoid, or by the inner end
of the outer fragment getting below and behind it. The
causes of displacement having been ascertained, it is
easy to apply the appropriate treatment. The outer
fragment is to be drawn outward, and, together with the
scapula, raised upward to a level with the inner frag-
ment, and retained in that position. The formula for
correcting the deformity is as follows: carry the shoulder
upward, outward, and backward.
In fracture of the acromial end of the clavicle, between
the conoid and trapezoid ligaments, only slight displace-
ment occurs, as these ligaments, from their oblique in-
sertion, serve to hold both portions of the bone in appo-
sition. Fracture, also, of the sternal end, internal to
the costoclavicular ligament, is attended with only slight
displacement, this ligament serving to retain the frag-
ments in close apposition.
Fracture of the acromion process usually arises from
violence applied to the upper and outer part of the
shoulder; it is generally known by the rotundity of the
shoulder being lost, from the Deltoid drawing the fractured portion downward and forward;
and .the displacement may easily be discovered by tracing the margin of the clavicle outward,
when the fragment will be found resting on the front and upper part of the head of the
humerus. In order to relax the anterior and outer fibres of the Deltoid (the opposing muscle),
the arm should be drawn forward across the chest and the elbow well raised, so that the head
of the bone may press the acromion process upward and retain it in its position.
Fracture of the coracoid process is an extremely rare accident, and is usually caused by a
sharp blow on the point of the shoulder. Displacement is here produced by the combined
actions of the Pectoralis minor, short head of the Biceps, and Coraco-brachialis, the former
muscle drawing the fragment inward, and the latter muscles directly downward, the amount of
displacement being limited by the connection of this process to the acromion by means of the
coraco-acromial ligament. In many cases there appears to have been little or no displacement,
FIG. 331. — Fracture of the middle of the
clavicle.
506 THE MUSCLES AND FASCIAE
\
from the fact that the coraco-clavicular ligament has remained intact, and has kept the separated
fragment from displacement. In order to relax these muscles and replace the fragments in
close apposition, the forearm should be flexed so as to relax the Biceps, and the arm drawn
forward and inward across the chest, so as to relax the Coraco-brachialis ; the humerus should
then be pushed upward against the coraco-acromial ligament, and the arm retained in that
position.
Fracture of the surgical neck of the humerus (Fig. 332) is very common, is attended with
considerable displacement, and its appearances correspond somewhat with those of dislocation
of the head of the humerus into the axilla. The upper fragment is slightly elevated under the
coraco-acromial ligament by the muscles attached to the greater and lesser tuberosities ; the
lower fragment is drawn inward by the Pectoralis major, Latissimus dorsi, and Teres major; and
the humerus is thrown obliquely outward from the side by the Deltoid, and occasionally elevated
so as to cause the upper end of the lower fragment to project
beneath and in front of the coracoid process. The deformity
is reduced by fixing the shoulder, and drawing the arm out-
ward and downward. To counteract the opposing muscles,
and to keep the fragments in position, a conical-shaped pad
should be placed with the apex in the axilla; while the fore-
arm is flexed to an angle of 90 degrees the shoulder is padded
with cotton, a shoulder-cap of plaster-of-Paris is applied to
«over the shoulder, a portion of the chest and back, and the
arm down to the external condyle (Scudder). The arm, with
the elbow slightly forward, is bandaged to the side. In some
cases a splint is placed between the axillary pad and the
inner side of the arm.
In fracture of the shaft of the humerus below the insertion
of the Pectoralis major, Latissimus dorsi, and Teres major,
and above the insertion of the Deltoid, there is also consider-
able deformity, the upper fragment being drawn inward by
the first-mentioned muscles, and the lower fragment upward
and outward by the Deltoid, producing shortening of the limb
and a considerable prominence at the seat of fracture, from
4 FIG. 332. — Fracture of the surgical the fractured ends of the bone riding over one another, espe-
neck of the humerus. cially if the fracture takes place in an oblique direction. The
fragments may be brought into apposition by extension from
the elbow, and are retained in that position by adopting the same means as in the preceding
injury, or by the use of an internal angular splint with three short humeral splints.
In fractures of the shaft of the humerus immediately below the insertion of the Deltoid, the
.amount of deformity depends greatly upon the direction of the fracture. If it occurs in a trans-
verse direction, only slight displacement takes place, the upper fragment being drawn a little
forward; but in oblique fracture the combined actions of the Biceps and Brachialis anticus
muscles in front and the Triceps behind draw upward the lower fragment, causing it to glide
over the upper fragment, either backward or forward, according to the direction of the fracture.
Simple extension reduces the deformity, and the application of an internal angular splint and
three short humeral splints will retain the fragments in apposition. Care should be taken not
to raise the elbow, but the forearm and hand may be supported in a sling.
Fracture of the humerus (Fig. 333) above the condyle deserves very attentive considera-
tion, as the general appearances correspond somewhat with those produced by separation
of the epiphysis of the humerus, and with those of dislocation of the radius and ulna back-
ward. If the direction of the fracture is oblique from above, downward and forward, the
lower fragment is drawn upward by the Brachialis anticus and Biceps in front and the Triceps
behind; and at the same time is drawn backward behind the upper fragment by the Triceps.
This injury may be diagnosticated from dislocation by the increased mobility in fracture, the
existence of crepitus, and the fact of the deformity being remedied by extension, on the discon-
tinuance of which it is reproduced. The age of the patient is of importance in distinguishing
this form of injury from separation of the epiphysis. If fracture occurs in the opposite direc-
tion to that shown in Fig. 333, the lower fragment is drawn upward and forward, causing a
considerable prominence in front, and the upper fragment projects backward beneath the
tendon of the Triceps muscle.
Fractures of the lower extremity of the humerus are spoken of as fractures in the neighbor-
hood of the elbow-joint. The term includes fracture of the external condyle, of the internal condyle,
at the base of the condyles, and T- or Y-shaped fracture, the two condyles being separated
from each other and from the shaft of the humerus. Such injuries are followed by great and
rapid swelling. Whenever possible the a>rays are used to aid in diagnosis, and the patient is
placed under ether, to set and dress the fracture.
In fracture of the inner condyle the fragment with the ulna passes up and back, and when
SURGICAL ANATOMY OF THE UPPER EXTREMITY 507
the forearm is extended the ulna projects posteriorly. The " carrying function " of the arm is
lost, because the forearm deviates to the ulnar side.
In all cases of fracture of the lower end of the humerus, except fracture at the base of
the condyles, effect reduction by traction upon the forearm, and supination, extension, and
bending the forearm slowly into acute flexion. In transverse fracture above the condyles
draw the forearm and the lower fragment downward and forward and push the upper frag-
ment back. A case can be treated by maintaining a position of acute flexion (Jones's position)
or by using an anterior angular splint. Allis and others treat in extension.
Fracture of the olecranon process (Fig. 334) is a frequent accident. The detached fragment
is displaced upward, by the action of the Triceps muscle, from half an inch to two inches; the
prominence of the elbow is consequently lost, and a deep hollow is felt at the back part of the
joint, which is much increased on flexing the limb. The patient at the same time loses, more
or less, the power of extending the forearm. The treatment consists in relaxing the Triceps by
extending the limb, and retaining it in the extended position by means of a long straight splint
applied to the front of the arm ; the fragments are thus brought into close apposition, and
may be further approximated by drawing down the upper fragment. Union is generally
ligamentous.
Fracture of the neck of the radius is an exceedingly rare accident, and is generally caused
by direct violence. Its diagnosis is somewhat obscure, on account of the slight deformity visible,
the injured part being surrounded by a large number of muscles; but the movements of prona-
tion and supination are entirely lost. The upper fragment is drawn outward by the Supinator
FIG. 333. — Fracture of the humerus above FIG. 334. — Fracture of the olecranon.
the condyles.
brevis, the extent of displacement being limited by the attachment of the orbicular ligament.
The lower fragment is drawn forward and slightly upward by the Biceps, and inward by the
Pronator radii teres, its displacement forward and upward being counteracted in some degree
by the Supinator brevis. The treatment essentially consists in relaxing the Biceps, Supinator
brevis, and Pronator radii teres muscles by flexing the forearm, and placing it in a position mid-
way between pronation and supination, extension having been previously made so as to bring
the parts i">. apposition.
In fracture of the radius below the insertion of the Biceps, but above the insertion of the
Pronator radii teres, the upper fragment is strongly supinated by the Biceps and Supinator
brevis, and at the same time drawn forward and flexed by the Biceps; the lower fragment is
pronated and drawn inward toward the ulna by the pronators. Thus there is extreme dis-
placement with very little deformity. In treating such a fracture the arm must be put up in
a position of supination, otherwise union will take place with great impairment of the move-
ments of the hand. In fractures of the radius below the insertion of the Pronator radii teres
(Fig. 335), the upper fragment is drawn upward by the Biceps and inward by the Pronator
radii teres, holding a position midway between pronation and supination, and a degree of fulness
in the upper half of the forearm is thus produced ; the lower fragment is drawn downward and
inward toward the ulna by the Pronator quadratus, and thrown into a state of pronation by the
same muscle; at the same time, the Supinator longus, by elevating the styloid process, into which
508
THE MUSCLES AND FASCIA
it is inserted, will serve to depress the upper end of the lower fragment still more toward the ulna.
In order to relax the opposing muscles the forearm should be bent, and the limb placed in a
position midway between pronation and supination; the fracture is then easily reduced by
extension from the wrist and elbow: well-padded splints should be applied on both sides of
the forearm from the elbow to the wrist; the hand being allowed to fall, will, by its own weight,
counteract the action of the Pronator quadratus and Supinator longus, and elevate the- lower
fragment to the level of the upper one.
In fracture of the shaft of the ulna the upper fragment retains its usual position, but the
lower fragment is drawn outward toward the radius by the Pronator quadratus, producing a
well-marked depression at the seat of fracture and some fulness on the dorsal and palmar sur-
faces of the forearm. The fracture is easily
reduced by extension from the wrist and fore-
arm. The forearm should be flexed, and
placed in a position midway between pronation
and supination, and well-padded splints ap-
plied from the elbow to the ends of the fingers.
In fracture of the shafts of the radius and
ulna together the lower fragments are drawn
upward, sometimes forward, sometimes back-
ward, according to the direction of the frac-
ture, by the combined actions of the Flexor and
Extensor muscles, producing a degree of ful-
ness on the dorsal or palmar surface of the
forearm; at the same time the two fragments are drawn into contact by the Pronator quad-
ratus, the radius being in a state of pronation : the upper fragment of the radius is drawn
upward and inward by the Biceps and Pronator radii teres to a higher level than the ulna;
the upper portion of the ulna is slightly elevated by the Brachialis anticus. The fracture may
be reduced by extension from the wrist and elbow, and the forearm should be placed in the
same position as in fracture of the ulna.
In fracture of the lower end of the radius (Colles's fracture) (Fig. 336) the displacement
which is produced is very considerable, and bears some resemblance to dislocation of the
carpus backward, from which it should be carefully distinguished. The lower fragment is
displaced backward and upward, but this displacement is probably due to the force of the
blow driving the portion of the bone into this position and not to any muscular influence.
The upper fragment projects forward, often lacerating the substance of the Pronator quad-
ratus, and is drawn by this muscle into close contact with the lower end of the ulna, causing a
FIG. 335. — Fracture of the shaft of the radius.
FIG. 336. — Fracture of the lower end of the radius.
projection on the anterior surface of the forearm, immediately above the carpus, from the flexor
tendons being thrust forward. This fracture may be distinguished from dislocation by the
deformity being removed on making sufficient extension, when crepitus may be occasionally
detected; at the same time, on extension being discontinued, the parts immediately resume
their deformed appearance. The age of the patient will also assist in determining whether
the injury is fracture or separation of the epiphysis. Reduction is effected by hyperextension,
longitudinal traction, and forced flexion.1 The posterior straight splint with suitable pads is
the best dressing.
1 R. J. Levis.
OF THE LOWER EXTREMITY
509
MUSCLES AND FASCLffi OF THE LOWER EXTREMITY.
The Muscles of the Lower Extremity are subdivided into groups corresponding
with the different regions of the limb.
I. ILIAC REGION.
Psoas magnus.
Psoas parvus.
Iliacus.
II. THIGH.
1. Anterior Femoral Region.
Tensor fascise Femoris.
Sartorius.
Rectus.
Quadriceps Vastus externus.
extensor. Vastus internus.
' Crureus.
Subcrureus.
2. Internal Femoral Region.
Gracilis.
Pectineus.
Adductor longus.
Adductor brevis.
Adductor magnus.
3. Gluteal Region.
Gluteus maximus.
Gluteus medius.
Gluteus minimus
Pyriformis.
Obturator internus.
Gemellus superior.
Gemellus inferior.
Quadratus femoris.
Obturator externus.
4. Posterior Femoral Region.
Biceps.
Semitendinosus.
Semimembranosus.
III. LEG.
5. Anterior Tibio-fibular Region.
Tibialis anticus.
Extensor proprius hallucis.
Extensor longus digitorum.
Peroneus tertius.
6. Posterior Tibio-fibular Region.
Superficial Layer.
Gastrocnemius.
Soleus.
Plantaris.
Deep Layer.
Popliteus.
Flexor longus hallucis.
Flexor longus digitorum.
Tibialis posticus.
7. Fibular Region.
Peroneus longus.
Peroneus brevis.
IV. FOOT.
8. Dorsal Region.
Extensor brevis digitorum.
9. Plantar Region.
First Layer.
Abductor hallucis.
Flexor brevis digitorum.
Abductor minimi digiti.
Second Layer.
Flexor accessorius.
Lumbricales.
Third Layer.
Flexor brevis hallucis.
Adductor obliquus hallucis.
Flexor brevis minimi digiti.
Adductor transversus hallucis,
Fourth Layer.
The Interossei-
510
THE MUSCLES AND FASCIA
I. MUSCLES AND FASCI-ffl OF THE ILIAC REGION.
Psoas magnus.
Psoas parvus.
Iliacus.
Dissection. — No detailed description is required for the dissection of these muscles. On
the removal of the viscera from the abdomen they are exposed, covered by the peritoneum and
a thin layer of fascia, the iliac fascia.
Iliac Fascia (fascia iliaca). — The iliac fascia1 is the aponeurotic layer which
lines the back part of the abdominal cavity, and covers the Psoas and Iliacus
muscles throughout their whole extent. It is thin above, and becomes gradually
thicker below as it approaches the crural arch.
The Portion Covering the Psoas is attached, above, to the ligamentum arcuatum
internum; internally, by a series of arched processes to the intervertebral sub-
stances and prominent margins of the bodies of the vertebrae, and to the upper part
of the sacrum, the intervals so left, opposite the constricted portions of the bodies,
PROSTATIC
VEINS
PUDENDAL
VEINS
PUOENDAL
VESSELS
VISCERAL
LAYER OF
PELVIC FASCIA
ANAL FASCIA
PARIETAL
LAYER OF
PELVIC FASCIA
FIG. 337. — Horizontal section through the male pelvis at the level of the middle of the symphysis, of
the tuberosity of the ischial bones and of the greater trochanter.
transmitting the lumbar arteries and veins and filaments of the sympathetic cord.
Externally, above the crest of the ilium, this portion of the iliac fascia is continu-
ous with the anterior lamella of the lumbar fascia, but below the crest of the
ilium it is continuous with the fascia covering the Iliacus.
The Portion Investing the Iliacus is connected externally to the whole length
of the inner border of the crest of the ilium, and internally to the brim of the true
pelvis, where it is continuous with the periosteum; and at the ilio-pectineal emi-
nence it receives the tendon of insertion of the Psoas parvus, when that muscle
exists. External to the femoral vessels, this fascia is intimately connected to the
posterior margin of Poupart's ligament, and is continuous with the fascia transver-
salis. Immediately to the outer side of the femoral vessels the fascia iliaca is pro-
longed backward and inward from Poupart's ligament as a band, the ilio-pectineal
1 The student must not confound this fascia with the iliac portion of the fascia lata (see p. 517).
THE ILIAC REGION
511
ligament, which is attached to the ilio-pectineal eminence. The ligament divides
the space between Poupart's ligament and the innominate bone into two parts, the
inner of which (lacuna vasorum) transmits the femoral vessels, and contains the
margin of Gimbernat's ligament and also the femoral ring; the outer (lacuna
musculorum) the ilio-psoas and the anterior crural nerve (Fig. 338). Internal to
the vessels the iliac fascia is attached to the ilio-pectineal line behind the con-
joined tendon, where it is again continuous with the transversalis fascia; and,
corresponding to the point where the femoral vessels pass into the thigh, this
fascia descends behind them, forming the posterior wall of- the femoral sheath.
This portion of the iliac fascia which passes behind the femoral vessels is also
attached to the ilio-pectineal line beyond the limits of the attachment of the con-
joined tendon; at this part it is continuous with the pubic portion of the fascia lata
of the thigh. The external iliac vessels lie in front of the iliac fascia, but all" the
branches of the lumbar plexus behind it ; it is separated from the peritoneum by a
quantity of loose areolar tissue. The femoral or crural sheath (fascia cruris) is
POUPART'S
LIGAM ENT
ANTERIOR
CRURAL NERVE
\-FEMORAL ARTERY
ILIAC FASCIA
FEMORAL VEIN
GIMBERNAT'S
LIGAMENT
PECTINEUS
FIG. 338. — Poupart's ligament and the relation of the parts passing beneath it. (Poirier and Charpy.)
formed by the transversalis fascia in front of the vessels and the iliac fascia back
of them. The fasciae join to the inrier side of the femoral vein, a space, the femoral
canal, intervening between the vein and their junction.
Between the femoral vein and the edge of Gimbernat's ligament is the femoral or
crural ring (annulus femoralis) (Fig. 340). The crural or femoral canal (canalis
femoralis} is the interval between the femoral vein and the inner wall of the femoral
(crural) sheath. This canal extends from the femoral ring to the saphenous open-
ing. The femoral ring is closed by the septum crurale of Cloquet (septum femorale
\Cloqueti\), which is a process of transversalis fascia.
512 THE MUSCLES AND FASCIAE
The Psoas Magnus (m. psoas major} (Fig. 341) is a long fusiform muscle placed
on the side of the lumbar region of the spine and the margin of the pelvis. It arises
from the front of the bases and lower borders of the transverse processes of the
lumbar vertebrae by five fleshy slips ; also from the sides of the bodies and the corre-
sponding inter vertebral substances of the last thoracic and all the lumbar vertebra.
The muscle is connected to the bodies of the vertebrae by five slips; each slip is
attached to the upper and lower margins of two vertebras, and to the intervertebral
substance between them, the slips themselves being connected by the tendinous
arches which extend across the constricted part of the bodies, and beneath which
pass the lumbar arteries and veins and filaments of the sympathetic cord. These
tendinous arches also give origin to muscular fibres, and protect the blood-vessels
and nerves from pressure during the action of the muscle. The first slip is attached
to the contiguous margins of the last thoracic and first lumbar vertebras; the last
to the contiguous margins of the fourth and fifth lumbar vertebrae, and to the
intervertebral substance. From these points the muscle descends across the
brim of the pelvis, and, diminishing gradually in size, passes beneath Pou-
part's ligament, and terminates in a tendon which, after receiving nearly the
whole of the fibres of the Iliacus, is inserted into the lesser trochanter of the
femur.
Relations. — In the lumbar region: by its anterior surface, which is placed behind
the peritoneum, with the iliac fascia, the ligamentumarcuatuminternum, the kidney,
Psoas parvus, renal vessels, ureter, spermatic vessels, genito-femoral nerve, and the
colon. In many cases the vermiform appendix rests upon the Psoas muscle (page
513). By its posterior surface, with the transverse processes of the lumbar vertebrae
and the Quadratus lumborum muscle, from which it is separated by the anterior
lamella of the lumbar fascia. The lumbar plexus is situated in the posterior part
of the substance of the muscle. By its inner side the muscle is in relation with the
bodies of the lumbar vertebrae, the lumbar arteries, the ganglia of the sympathetic
nerve, and their branches of communication with the spinal nerves; the lumbar
glands ; the vena cava inferior on the right and the aorta on the left side, and along
the brim of the pelvis with the external iliac artery. In the thigh it is in relation,
in front, with the fascia lata; behind, with the capsular ligament of the hip, from
which it is separated by a synovial bursa (bursa iliopectinea) , which frequently
communicates with the cavity of the joint through an opening of variable size;
between the tendon and part of the lesser trochanter is the bursa iliaca sub-
tendinea ; by its inner border, with the Pectineus and internal circumflex artery,
and also with the femoral artery, which slightly overlaps it: by its outer border,
with the anterior crural nerve and Iliacus muscle.
The Psoas Parvus (m. psoas minor) (Fig. 341) is a long slender muscle placed
in front of the Psoas magnus. It arises from the sides of the bodies of the last
thoracic and first lumbar vertebrae and from the intervertebral substance between
them. It forms a small flat muscular bundle, which terminates in a long flat
tendon inserted into the ilio-pectineal eminence, and, by its outer border, into
the iliac fascia. This muscle is often absent, and, according to Cruveilhier, is
sometimes double.
Relations. — It is covered by the peritoneum, and, at its origin, by the ligamentum
arcuatum internum; it rests on the Psoas magaus.
The Iliacus (Fig. 341) is a flat, triangular muscle which fills up the whole of the
iliac fossa. It arises from the upper two-thirds of this fossa and from the inner
margin of the crest of the ilium ; behind, from the ilio-lumbar ligament and base
of the sacrum ; in front, from the anterior superior and anterior inferior spinous
processes of the ilium, from the notch between them. The fibres converge to be
inserted into the outer side of the tendon of the Psoas, some of them being pro-
longed on to the shaft of the femur for about an inch below and in front of the
THE ILIAC REGION 513
lesser trochanter.1 The most external fibres are inserted into the capsule of the
hip-joint. ' If these fibres are separate they constitute the Ilio-capsularis muscle or
the Iliacus minor.
Relations. — Within the abdomen: by its anterior surface, with the iliac fascia,
which separates the muscle from the peritoneum, and with the external cutaneous
nerve; on the right side, with the caecum; on the left side, with the sigmoid flexure
of the colon; by its posterior surface, with the iliac fossa; by its inner border, with
the Psoas magnus and femoral nerve. In the thigh, it is in relation, by its anterior
surface, with the fascia lata, the Rectus and Sartorius muscles, and the profunda
femoris artery; behind, with the capsule of the hip-joint, a synovial bursa common
to it and the Psoas magnus being interposed.
Nerves. — The Psoas magnus is supplied by the anterior branches of the second
and third lumbar nerves; the Psoas parvus, when it exists, is supplied by the
anterior branch of the first lumbar nerve; and the Iliacus by the anterior branches
of the second and third lumbar nerves through the femoral.
Actions. — The Psoas and Iliacus muscles, acting from above, flex the thigh
upon the pelvis. Acting from below, the femur being fixed, the muscles of
both sides bend the lumbar portion of the spine and pelvis forward. They also
serve to maintain the erect position, by supporting the spine and pelvis upon
the femur, and assist in raising the trunk when the body is in the recumbent
posture.
The Psoas parvus is a tensor of the iliac fascia. It assists in flexing the lumbar
spine laterally, the pelvis being its fixed point.
Surgical Anatomy. — There is no definite septum between the portions of the iliac fascia
covering the Psoas and Iliacus respectively, and the fascia is only connected to the subjacent
muscles by a quantity of loose connective tissue. When an abscess forms beneath this fascia,
as it is very apt to do, the matter is contained in an osseo-fibrous cavity, which is closed on all
sides within the abdomen, and is open only at its lower part, where the fascia is prolonged over
the muscle into the thigh.
Abscess within the sheath of the Psoas muscle (psoas abscess} is generally due to tuberculous
caries of the bodies of the lower thoracic or of the lumbar vertebrae. When the disease is in the
thoracic region, the matter tracts down the posterior mediastinum, in front of the bodies of the
vertebrae, and, passing beneath the ligamentum arcuatum internum, enters the sheath of the Psoas
muscle, down which it passes as far as the pelvic brim ; it then gets beneath the iliac portion of the
fascia and fills up the iliac fossa. In consequence of the attachment of the fascia to the pelvic
brim, it rarely finds its way into the pelvis, but passes by a narrow opening under Poupart's liga-
ment into the thigh, to the outer side of the femoral vessels. It thus follows that a Psoas abscess
may be described as consisting of four parts: (1) a somewhat narrow channel at its upper part, in
the Psoas sheath; (2) a dilated sac in the iliac fossa ; (3) a constricted neck under Poupart's liga-
ment; and (4) a dilated sac in the upper part of the thigh. When the lumbar vertebrae are the seat
of the disease, the matter finds its way directly into the substance of the muscle. If a Psoas abscess
forms the muscular fibres are destroyed, and the nervous cords contained in the abscess are isolated
and exposed in its interior; the femoral vessels which lie in front of the fascia remain intact, and
the peritoneum seldom becomes implicated. All Psoas abscesses do not, however, pursue this
course: the matter may leave the muscle above the crest of the ilium, and, tracking backward,
may point in the loin (lumbar abscess) ; or it may point above Poupart's ligament in the inguinal
region ; or it may follow the course of the iliac vessels into the pelvis, and, passing through the
great sacro-sciatic notch, discharge itself on the back of the thigh; it may open into the bladder
or find its way into the perinaeum, or it may pass down the thigh to the popliteal space or even
lower. Strain of the Psoas muscle is not unusual, and induces pain which may be mistaken
for appendicitis. The bursa beneath the tendon of the Psoas and Iliacus and the hip-joint or
that between the tendon and the lesser trochanter may greatly enlarge and produce pain and
disablement. Byron Robinson* pointed out that trauma of the Psoas muscle may be an
important factor in the etiology of appendicitis, trauma may induce periappendicular adhe-
sions and adhesions interfere with the circulation of blood and faeces. Robinson says, in the
previously quoted article, that in 46 per cent, of men and in 20 per cent, of women the
appendix rests on the Psoas muscle.
1 Th^-Ps0^ magnus, Psoas parvus, and Iliacus are regarded by His and others as a single muscle, the Ilio
psoas (Fig. 338). 2 Annals of Surgery, April, 1901.
33
514
THE MUSCLES AND FASCIAE
II. MUSCLES AND FASCI-ffi OF THE THIGH.
1. The Anterior Femoral Region.
[ Rectus.
Tensor fasciae femoris. Quadriceps I Vastus externus.
Sartorius. extensor, j Vastus internus.
I Crureus.
Subcrureus.
Dissection. — To expose the muscles and fasciae in this region, make an incision along
Poupart's ligament, from the anterior superior spine of the ilium to the spine of the os pubis;
a vertical incision from the centre of this, along the middle of the thigh to below the knee-joint;
and a transverse incision from the inner to the outer side of the leg, at the lower end of the ver-
tical incision. The flaps of integument having been removed, the superficial and deep fasciae
should be examined. The more advanced student should commence the study of this region by
an examination of the anatomy of femoral hernia and Scarpa's triangle, the incisions for the
dissection of which are marked out in Fig. 339.
Superficial Fascia. — The superficial fascia forms a continuous layer over the
whole of the thigh. It consists of areolar tissue, containing in its meshes much fat,
and is capable of being separated into two or
more layers, between which are found the super-
ficial vessels and nerves. It varies in thickness
in different parts of the limb: in the groin it
is thick, and the two layers are separated from
of one another by the superficial inguinal lymphatic
glands, the internal saphenous vein, and several
smaller vessels. One of these two layers, the
superficial, is continuous above with the super-
ficial fascia of the abdomen and the back. In-
ternally it is continuous with the superficial
fascia of the perineum. The deep layer of the
superficial fascia is a very thin fibrous layer,
best marked on the inner side of the long
saphenous vein and below Poupart's ligament.
It is placed beneath the subcutaneous vessels
and nerves and upon the surface of the fascia
lata. It is intimately adherent to the fascia lata
a little below Poupart's ligament. It covers the
saphenous opening (Fig. 340) in the fascia lata,
being closely united to the margins of the open-
ing, and is connected to the sheath of the fem-
3. Front of leg. oral vessels by its under surface. The portion
of the fascia covering this aperture is perforated
by the internal saphenous vein and by numer-
ous blood- and lymphatic vessels; hence it has
been termed the cribriform fascia (fascia cribrosa),
theopenings for these vessels having been likened
to the holes in a sieve. . The cribriform fascia
adheres closely both to the superficial fascia and
to the fascia lata, so that it is described by some
anatomists as part of the fascia lata, but is usually
considered (as in this work) as belonging to the
superficial fascia. It is not until the cribriform
fascia has been cleared away that the saphenous opening is seen, so that this open-
ing does not in ordinary cases exist naturally, but is the result of dissection. Mr.
1. Dissection
femoral hernia,
and Scarpa's
triangle.
2. Front of thigh.
4- Dorsum of foot.
FIG. 339. — Dissection of lower extremity.
Front view.
THE ANTERIOR FEMORAL REGION
515
Caliender, however, speaks of cases in which, probably as the result of pressure
from enlarged inguinal lymphatic glands, the fascia has become atrophied, and a
saphenous opening exists independent of dissection. A femoral hernia in passing
through the saphenous opening receives the cribriform fascia as one of its cover-
ings. A large subcutaneous bursa (bur so. praepatellaris subcutanea) is found in the
superficial fascia over the patella, and another (bursa trochanterica subcutanea]
in the superficial fascia over the great trochanter.
Deep Fascia or Fascia Lata (Fig. 340) . — The deep fascia of the thigh is exposed
on the removal of the superficial fascia, and is named, from its great extent, the fascia
lata ; it forms a uniform investment for the whole of this region of the limb, but varies
in thickness in different parts; thus, it is thicker in the upper and outer part of
the thigh, where it receives a fibrous expansion from the Gluteus maximus muscle,
and the Tensor fasciae femoris is inserted between its layers: it is very thin behind,
and at the upper and inner part where it covers the Adductor muscles, and again
POUPART'S
LIGAMENT
INTERCOLUMNAR
FIBRES
M BE R NAT'S
LIGAMENT
iAPHENOUS
OPENING
FEMORAL
VEIN
LONG
iAPHENOUS
VEIN
EXTERNAL
•ABDOMINAL
RING
FIG. 340.— Right external abdominal ring and saphenous opening in the male. (Spalteholz).
becomes stronger around the knee, receiving fibrous expansions from the tendon of
the Biceps externally, from the Sartorius internally, and from the Quadriceps
extensor in front. The fascia lata is attached, above and behind, to the back of
the sacrum and coccyx; externally, to the crest of the ilium; in front, to Pou-
part's ligament and to the body of the os pubis; and internally, to the descend-
ing ramus of the os pubis, to the ramus and tuberosity of the ischium, and to the
lower border of the great sacro-sciatic ligament. From its attachment to the crest
of the ilium it passes down over the Gluteus medius muscle to the upper border
of the Gluteus maximus, where it splits into two layers, one passing superficial to
and the other beneath this muscle. At the lower border of the muscle the two layers
reunite. Externally the fascia lata receives the greater part of the tendon of inser-
tion of the Gluteus maximus, and becomes proportionately thickened. The
portion of the fascia lata arising from the front part of the crest of the ilium, cor-
516
responding to the origin of the Tensor fascia;
femoris, passes down the outer side of the thigh
as two layers, one superficial to and the other
beneath this muscle. The deep layer is a con-
tinuation of the tendinous fibres of the Gluteus
maximus muscle and the superficial layer is
chiefly a continuation of the tendinous fibres of
the Tensor fasciae femoris, but receives some
fibres from the fascia covering the Gluteus
medius muscle.1 These layers at the lower
end of the muscle become blended into a thick
and strong band, having first received the in-
sertion of the muscle. This band is continued
downward, under the name of the ilio-tibial band
(tract-us iliotibialis [Maissiati]), to be inserted
into the external tuberosity of the tibia. A
strengthening band of transverse fibres is placed
in the gluteal groove or s\ilc\is(sulcus glutaeus)and
another is placed across the roof of the popliteal
space. Below, the fascia lata is attached to all
the prominent points around the knee-joint —
viz., the condyles of the femur, tuberosities of
the tibia, and head of the fibula. On each side
of the patella it is strengthened by transverse
fibres given off from the lower part of the Vasti
muscles, which are attached to and support this
bone. Of these the outer fibres are the stronger,
and are continuous with the ilio-tibial band.
From the inner surface of the fascia lata are
given off two strong intermuscular septa, which
are attached to the whole length of the linea
aspera and its prolongations above and below:
the external intermuscular septum (septum in-
termusculare laterale) is the stronger. It extends
from the insertion of the Gluteus maximus to
the outer condyle, separates the Vastus externus
in front from the short head of the Biceps be-
hind, and gives partial origin to these muscles;
the internal intermuscular septum (septum inter-
musculare mediate), the thinner of the two,
separates the Vastus internus from the Adductor
and Pectineus muscles. Besides these there
are numerous smaller septa, separating the in-
dividual muscles and enclosing each in a dis-
tinct sheath. At the upper and inner part of
the thigh, a little below Poupart's ligament, a
large oval-shaped aperture is observed after
the superficial fascia has been cleared off: it
transmits the internal saphenous vein and other
smaller vessels, and is termed the saphenous
opening (fossa ovalis) (Fig. 340). This opening
is covered by a portion of the deep layer of the
FIG. 341. — Muscles of the iliac and anterior ' Werner Spalteholz's Hand Atlas of Human Anatomy. Edited
femoral region. and translated by Lewellys F. Barker.
m
THE ANTERIOR FEMORAL REGION 517
superficial fascia, the cribriform fascia. In order more correctly to consider the
mode of formation of this aperture, the fascia lata in this part of the thigh is
described as consisting of two portions — an iliac portion and a pubic portion.
Iliac Portion. — The iliac portion, the superficial layer of the fascia lata or the
Sartorial portion of the fascia lata, is all that part of the fascia lata on the outer
side of the saphenous opening. It is attached, externally, to the crest of the
ilium and its anterior superior spine, to the whole length of Poupart's ligament as
far internally as the spine of the os pubis, and to the pectineal line in conjunction
with Gimbernat's ligament. From the spine of the os pubis it is reflected down-
ward and outward, forming an arched margin, the falciform process or the falciform
margin of Burns (margo falciformis), or the superior cornu of the saphenous opening
(cornu super ius). This margin overlies and is adherent to the anterior layer of
the sheath of the femoral vessels: to its edge is attached the cribriform fascia;
and, below, it is continuous with the pubic portion of the fascia lata. The
femoral ligament, or the ligament of Hey, is the point at which the falciform
process joins the base of Gimbernat's ligament.
Pubic Portion. — The pubic portion, or the pectineal portion, or the deep layer of
the fascia lata, is situated at the inner side of the saphenous opening : at the lower
margin of this aperture it is continuous with the iliac portion. The lower concave
margin of the saphenous opening where the two layers of fascia are continuous is
called the inferior cornu (cornu inferius). Traced upward, the pubic portion covers
the surface of the Pectineus, Adductor longus, and Gracilis muscles, and, passing
behind the sheath of the femoral vessels, to which it is closely united, is continu-
ous with the sheath of the Psoas and Iliacus muscles, and is attached above to
the ilio-pectineal line, where it becomes continuous with the iliac fascia. From
this description it may be observed that the iliac portion of the fascia lata passes
in front of the femoral vessels, and the pubic portion behind them, so that an
apparent aperture exists between the two, through which the internal saphenous
joins the femoral vein.1
Surgical Anatomy. — The ilio-tibial band at a point between the crest of the ilium and the
great trochanter is so tense that it is impossible to sink the fingers in deeply in this region. Dr.
Allis points out that in fracture of the neck of the femur the great trochanter mounts toward
the iliac crest, the ilio-tibial band relaxes, and the fingers can be sunk deeply into the space
between the great trochanter and the iliac crest — Allis's sign. Allis's sign indicates shorten-
ing. A Psoas abscess usually points at the termination of the Psoas muscle, but the tuberculous
matter may be directed down the thigh beneath the fascia lata, and it may reach the popliteal
space or even lower.
The fascia should now be removed from the surface of the muscles. This may be effected by
pinching it up between the forceps, dividing it, and separating it from each muscle in the course
of its fibres.
The Tensor Fasciae Femoris (m. tensor fasciae laiae, m. tensor vaginae femoris)
(Fig. 341) arises from the anterior part of the outer lip of the crest of the ilium,
and from the outer surface of the anterior superior spinous process, and part of
the outer border of the notch below it, between the Gluteus medius and Sartorius,
and from the surface of the fascia covering the Gluteus medius. It is inserted
between two layers of the fascia lata, about one-fourth down the outer side of
the thigh. From the point of insertipn the fascia is continued downward to the
external tuberosity of the tibia as a thickened band, the ilio-tibial band.
Relations. — By its superficial surface, with the fascia lata and the integument;
by its deep surface, with the Gluteus medius, Rectus femoris, and Vastus externus
muscles, and the ascending branches of the external circumflex artery; by its
anterior border, with the Sartorius, from which it is separated below by a triangular
1 These parts will be again more particularly described with the anatomy of Hernia.
518 THE MUSCLES AND FASCIAE
space, in which is seen the Rectus femoris; by its posterior border, with the
Gluteus medius.
The Sartorius (Fig. 341), the longest muscle in the body, is flat, narrow, and
ribbon-like; it arises by tendinous fibres from the anterior superior spinous process
of the ilium and the upper half of the notch below it, passes obliquely across the
upper and anterior part of the thigh, from the outer to the inner side of the limb,
then descends vertically, as far as the inner side of the knee, passing behind the
inner condyle of the femur, and terminates in a tendon which, curving obliquely
forward, expands into a broad aponeurosis, inserted in front of the Gracilis and
Semitendinosus, into the upper part of the inner surface of the shaft of the tibia,
nearly as far forward as the crest. The upper part of the tendon is curved back-
ward over the upper edge of the tendon of the Gracilis so as to be inserted behind
it. An offset is derived from the upper margin of this aponeurosis, which blends
with the fibrous capsule of the knee-joint, and another, given off from its lower
border, blends with the fascia on the inner side of the leg.
The relations of this muscle to the femoral artery should be carefully examined,
as it constitutes the chief guide in tying the vessel. In the upper third of the
thigh it forms the outer side of a triangular space, Scarpa's triangle (trigonum
femorale), the inner side of which is formed by the inner border of the Adductor
longus, and the base, which is turned upward, by Poupart's ligament; the femoral
artery passes perpendicularly through the middle of this space from its base to
its apex. In the middle third of the thigh the femoral artery lies first along
the inner border, and then behind the Sartorius.
Relations. — By its superficial surface, with the fascia lata and integument; by
its deep surface, with the Rectus, Iliacus, Vastus internus, femoral nerve, sheath
of the femoral vessels, Adductor longus, Adductor magnus, Gracilis, Semitendi-
nosus, long saphenous nerve, and internal lateral ligament of the knee-joint.
Frequently there is a bursa (bursa m. sartorii propria) between the tendon of the
Sartorius and the tendons of the Gracilis and Semimembranosus. It may be in
communication with the bursa anserina.
The Quadriceps Extensor (m. quadriceps femoris} (Fig. 341) includes the four
remaining muscles on the front of the thigh. It is the great Extensor muscle
of the leg, forming a large fleshy mass which covers the front and sides of the
femur, being united below into a single tendon, attached to the patella, and
above subdivided into separate portions, which have received distinct names.
Of these, one occupying the middle of the thigh, connected above with the ilium,
is called the Rectus femoris, from its straight course. The other divisions lie in
immediate connection with the shaft of the femur, which they cover from the
trochanters to the condyles. The portion on the outer side of the femur is
termed the Vastus externus; that covering the inner side, the Vastus internus;
and that covering the front of the femur, the Crureus.
The Rectus Femoris is situated in the middle of the anterior region of the thigh;
it is fusiform in shape, and its superficial fibres are arranged in a bipenniform
manner, the deep fibres running straight down to the deep aponeurosis. It arises
by two tendons: one, the anterior or straight, from the anterior inferior spinous
process of the ilium; the other, the posterior or reflected tendon, from a groove
above the brim of the acetabulum; the two unite at an acute angle and spread
into an aponeurosis, which is prolonged downward on the anterior surface of the
muscle and from which the muscular fibres arise.1 The muscle terminates in a
broad and thick aponeurosis, which occupies the lower two-thirds of its posterior
surface, and, gradually becoming narrowed into a flattened tendon, is inserted
1 Mr. W. R. Williams, in an interesting paper in the Journ. of Anat. and Phya., vol. xiii. p. 204, points
out that the reflected tendon is the real origin of the muscle, and is alone present in early tetal life. The
direct tendon is merely an accessory band of condensed fascia. The paper will well repay perusal, though in
some particulars I think the description in the text more generally accurate. — ED. of 15th English edition.
THE ANTERIOR FEMORAL REGION
519
FEMORAL VEIN
SAPHENOUS VEIN
FEMORAL ARTERY FEMORAL NERVE
PROFUNDA ARTERY
BRANCHES OF
OBTURATOR NE
EXTERNAL CUTANEOUS
NERVE
FIG. 342. — Transverse section of the thigh below the trochanter minor. (After Braune.)
POSTERIOR
TIBIAL
ARTERY.
FIG. 343.— Transverse section at the middle of the leg. In front of the interosseous membrane are the
anterior tibial vessels and nerve; in front of the soleus, the posterior tibial vessels and nerve; and close to
the fibula, the peroneal vessels. (After Braune.)
520 THE MUSCLES AND FASCIA
into the patella in common with the Vasti and Crureus. Between the tendon of
origin and the acetabulum there is often a bursa (bursa m. recti femoris) .
Relations. — By its superficial surface, with the anterior fibres of the Glutens
minimus, the Tensor fasciae femoris, the Sartorius, and the Iliacus; by its lower
three-fourths, with the fascia lata. By its posterior surface, with the hip-joint,
the external circumflex vessels, branches of the femoral nerve, and the Crureus
and Vasti muscles.
The Vastus Externus (m. vastus lateralis) is the largest part of the Quadriceps
extensor. It arises by a broad aponeurosis, which is attached to the upper half
of the anterior intertrochanteric line, to the anterior and inferior borders of the
root of the great trochanter, to the outer lip of the gluteal ridge, and to the upper
half of the outer lip of the linea aspera; this aponeurosis covers the upper three-
fourths of the muscle, and from its inner surface many fibres take origin. A few
additional fibres arise from the tendon of the Gluteus maximus, and from the
external intermuscular septum between the Vastus externus and short head of the
Biceps. The fibres form a large fleshy mass, which is attached to a strong aponeu-
rosis, placed on the under surface of the muscle at its lower part: this becomes
contracted and thickened into a flat tendon, which is inserted into the outer
border of the patella, blending with the great Extensor tendon, and giving an
expansion to the capsule of the knee-joint. Some of the fibres run down by the
side of the patella to the condyle of the tibia, and are called the rptinacula patellae
later ale.
Relations. — By its superficial surface, with the Rectus, the Tensor fasciae femoris,
the fascia lata, and the tendon of the Gluteus maximus, from which it is separated
by a synovial bursa. By its deep surface, with the Crureus, some large branches
of the external circumflex artery and femoral nerve being interposed.
The Vastus Internus and Crureus appear to be inseparably united, but when
the Rectus femoris has been reflected, a narrow interval will be observed extending
upward from the inner border of the patella between the two muscles. Here they
can be separated, and the separation should be continued upward as far as the
lower part of the anterior intertrochanteric line, where, however, the two muscles
are frequently continuous.
The Vastus Internus (m. vastus medialis) arises from the lower half of the
anterior intertrochanteric line, the spiral line, the inner lip of the linea aspera,
the upper part of the internal supra-condylar line, and the tendon of the Adductor
magnus and the internal intermuscular septum. Its fibres are directed downward
and forward, and are chiefly attached to an aponeurosis which lies on the deep
surface of the muscle and is inserted into the inner border of the patella and
the Quadriceps extensor tendon, an expansion being sent to the capsule of the
knee-joint. Some of the fibres run down by the side of the patella to the con-
dyle of the tibia and are called the retinacula patellae mediale.
The Crureus (m. vastus intermedius) arises from the front and outer aspect of
the shaft of the femur in its upper two-thirds and from the lower part of the
external intermuscular septum. Its fibres end in a superficial aponeurosis, which
forms the deep part of the Quadriceps extensor tendon.
Relations. — The inner edge of the Crureus is in contact with the anterior edge
of the Vastus internus, but when separated from each other, as directed above, the
latter muscle is seen merely to overlap the inner aspect of the femoral shaft without
taking any fibres of origin from it. The Vastus internus is partly covered by the
Rectus and Sartorius, but where these separate near the knee it becomes superficial,
and produces a well-marked prominence above the inner aspect of the knee. In
the middle third of the thigh it forms the outer wall of Hunter's canal (canalis
adductorius [Hunteri]), which contains the femoral vessels and the long saphenous
nerve — the roof of the canal being formed by a strong fascia which extends from
THE ANTERIOR FEMORAL REGION 521
the Vastus interims to the Adduc tores longus and magnus. The Crureus is almost
completely hidden by the Rectus femoris and Vastus externus. The deep surface
of the two muscles is in relation with the femur and Subcrureus muscles. A
synovial bursa (bursa suprapatellaris) is situated between the femur and the
portion of the Quadriceps extensor tendon above the patella; in the adult it
communicates with the synovial cavity of the knee-joint.
The tendons of the different portions of the Quadriceps extensor unite at the
lower part of the thigh, so as to form a single strong tendon, which is inserted into
the upper part of the patella, some few fibres passing over it to blend with the
Ligamentum patellae. More properly, the patella may be regarded as a sesamoid
bone, developed in the tendon of the Quadriceps; and the Ligamentum patellae,
which is continued from the lower part of the patella to the tuberosity of the tibia,
as the proper tendon of insertion of the muscle. A synovial bursa, the deep patel-
lar bursa (bursa infrapatellaris prof undo), is interposed between the tendon and
the upper part of the tuberosity of the tibia; and another, the pre-patellar bursa
(bursa praepatellaris subcutanea), is placed over the patella itself. This latter
bursa often becomes enlarged, constituting "housemaid's knee."
The Subcrureus (m. articularis genu) is a small muscle, usually distinct from
the Crureus, but occasionally blended with it, which arises from the anterior sur-
face of the lower part of the shaft of the femur, and is inserted into the upper
part of the cul-de-sac of the capsular ligament which projects upward beneath
the Quadriceps for a variable distance. It sometimes consists of several separate
muscular bundles.
Nerves. — The Tensor fasciae femoris is supplied by the fourth and fifth lumbai
and first sacral nerves through the superior gluteal nerve; the other muscles of
this region, by the second, third, and fourth lumbar nerves, through branches of
the femoral.
Actions. — The Tensor fasciae femoris is a tensor of the fascia lata; continuing
its action, the oblique direction of its fibres enables it to abduct and to rotate the
thigh inward. In the erect posture, acting from below, it will serve to steady the
pelvis upon the head of the femur, and by means of the ilio-tibial band it steadies
the condyles of the femur on the articular surfaces of the tibia, and assists the
Gluteus maximus in supporting the knee in the extended position. The Sartorius
flexes the leg upon the thigh, and, continuing to act, flexes the thigh upon the
pelvis; it next rotates the thigh outward. It was formerly supposed to adduct the
thigh, so as to cross one leg over the other, and hence received its name of Sar-
torius, or tailor's muscle (sartor, a tailor), because it was supposed to assist in cross-
ing the legs in the squatting position. When the knee is bent the Sartorius assists
the Semitendinosus, Semimembranosus, and Popliteus in rotating the tibia inward.
Taking its fixed point from the leg, it flexes the pelvis upon the thigh, and, if one
muscle acts, assists in rotating the pelvis. The Quadriceps extensor extends the
leg upon the thigh. The Rectus muscle assists the Psoas and Iliacus in supporting
the pelvis and trunk upon the femur. It also assists in flexing the thigh on the
pelvis, or if the thigh is fixed it will flex the pelvis. The Vastus internus draws
the patella inward as well as upward.
Surgical Anatomy. — A few fibres of the Rectus muscle are liable to be ruptured from-
severe strain. This accident is especially liable to occur during the games of football and cricket,
and is sometimes known as cricket thigh. The patient experiences a sudden pain in the part,
as if he had been struck, and the Rectus muscle stands out and is felt to be tense and rigid. The
accident is often followed by considerable swelling from inflammatory effusion. Occasionally the
Quadriceps extensor may be torn away from its insertion into the patella, or the tendon of the
quadriceps may be ruptured about an inch above the bone. This accident is caused in the same
manner that fracture of the patella by muscular action is produced — viz., by a violent muscular
effort to prevent falling whilst the knee is in a position of semiflexion. A distinct gap can be
522
felt above the patella, and, owing to the retraction of the muscular fibres, union may fail to take
place. Sudden and powerful contraction of the Quadriceps extensor femoris is the cause of
transverse fracture of the patella.
2. The Internal Femoral Region.
Gracilis. Adductor longus.
Pectineus. Adductor brevis.
Adductor magnus.
Dissection. — These muscles are at once exposed by removing the fascia from the forepart
and inner side of the thigh. The limb should be abducted, so as to render the muscles tense
and easier of dissection.
The Gracilis (Figs. 341, 346, and 349) is the most superficial muscle on the
inner side of the thigh. It is thin and flattened, broad above, narrowing and taper-
ing below. It arises by a thin aponeurosis from the lower half of the margin of the
symphysis and the anterior half of the pubic arch. The fibres pass vertically down-
ward, and terminate in a rounded tendon which passes behind the internal condyle
of the femur, and, curving round the inner tuberosity of the tibia, becomes flattened,
and is inserted into the upper part of the inner surface of the shaft of the tibia, below
the tuberosity. A few of the fibres of the lower part of the tendon are prolonged
into the deep fascia of the leg. The tendon of this muscle is situated immediately
above that of the Semitendinosus, and its upper edge is overlapped by the tendon
of the Sartorius, with which it is in part blended. As it passes across the internal
lateral ligament of the knee-joint it is separated from it by a synovial bursa
(bursa anserina) common to it and the Semitendinosus muscle.
Relations. — By its superficial surf ace, with the fascia lataand the Sartorius below:
the internal saphenous vein crosses it obliquely near its lower part, lying superficial
to the fascia lata; the internal saphenous nerve emerges between its tendon and
that of the Sartorius ; by its deep surface, with the Adductor brevis and the Adductor
magnus and the internal lateral ligament of the knee-joint.
The Pectineus (Fig. 341) is a flat, quadrangular muscle, situated at the anterior
part of the upper and inner aspect of the thigh. It arises from the linea ilio-pec-
tinea, and to a slight extent from the surface of the bone in front of it between the
pectineal eminence and spine of the os pubis, and from the fascia covering the
anterior surface of the muscle; the fibres pass downward, backward, and outward,
to be inserted into a rough line leading from the lesser trbchanter to the linea aspera.
Relations. — By its anterior surface, with the pubic portion of the fascia lata,
which separates it from the femoral vessels and internal saphenous vein; by its
posterior surface, with the capsular ligament of the hip-joint, the Adductor brevis
and Obturator externus muscles, the obturator vessels and nerve being interposed;
by its outer border, with the Psoas, a cellular interval separating them, through
which pass the internal circumflex vessels; by its inner border, with the margin of
the Adductor longus. There is usually a bursa (bursa m. pectinei) between the
pectineus and the tendon of the psoas and iliacus.
The Adductor Longus (Figs. 341 and 344), the most superficial of the three
Adductors, is a flat triangular muscle lying on the same plane as the Pectineus.
It arises, by a flat narrow tendon, from the front of the os pubis, at the angle of
junction of the crest with the symphysis; and soon expands into a broad fleshy
belly, which, passing downward, backward, and outward, is inserted, by an
aponeurosis, into the linea aspera, between the Vastus interims and the Adductor
magnus, with both of which it is usually blended.
Relations. — By its anterior surface, with the fascia lata, the Sartorius, and, near
its insertion, with the femoral artery and vein; by its posterior surface, with the
Adductor brevis and magnus, the anterior branches of the obturator nerve, and
THE INTERNAL FEMORAL REGION
523
with the profunda artery and vein near its insertion; by its older border, with the
Pectineus; by its inner border, with the Gracilis.
The Pectineus and Adductor longus should now
be divided near their origin, and turned down-
ward, when the Adductor brevis and Obturator ex-
ternus will be exposed.
The Adductor Brevis (Fig. 344) is situ-
ated immediately behind the two preceding
muscles. It is somewhat triangular in
form, and arises by a narrow origin from
the outer surface of the body and descend-
ing ramus of the os pubis, between the
Gracilis and Obturator externus. Its fibres
passing backward, outward, and downward,
are inserted, by an aponeurosis, into the
lower part of the line leading from the lesser
trochanter to the linea aspera and the upper
part of the same line, immediately behind
the Pectineus and upper part of the Ad-
ductor longus.
Relations. — By its anterior surface, with
the Pectineus, Adductor longus, profunda
femoris artery, and anterior branches of the
obturator nerve; by its posterior surface,
with the Adductor magnus and posterior
branch of the obturator nerve ; by its outer
border, with the internal circumflex artery,
the Obturator externus, and conjoined ten-
don of the Psoas and Iliacus; by its inner
border, with the Gracilis and Adductor
magnus. This muscle is pierced, near its
insertion, by the second or by the first and
second perforating branches of the pro-
funda femoris artery.
The Adductor brevis should now be cut away
near its origin, and turned outward, when the en-
tire extent of the Adductor magnus will be exposed.
The Adductor Magnus (Fig. 344) is a
large triangular muscle forming a septum
between the muscles on the inner and those
on the back of the thigh. It arises from a
small part of the descending ramus of the
os pubis, from the ramus of the ischium,
and from the outer margin of the inferior
part of the tuberosity of the ischium. Those
fibres which arise from the ramus of the os
pubis are very short, horizontal in direction,
and are inserted into the rough line leading
from the great trochanter to the linea aspera,
internal to the Gluteus maximus. They are
considered by some a distinct muscle and called the Adductor minimus. The fibres
taking origin from the ramus of the ischium are directed downward and outward
FIG. 344.-
-Deep muscles of the internal femoral
region.
524 THE MUSCLES AND FASCIA
with different degrees of obliquity, to be inserted, by means of a broad aponeurosisr
into the linea aspera and the upper part of its internal prolongation below. The
internal portion of the muscle, consisting principally of those fibres which arise from
the tuberosity of the ischium, forms a thick fleshy mass consisting of coarse bundles
which descend almost vertically, and terminate about the lower third of the thigh
in a rounded tendon, which is inserted into the Adductor tubercle on the inner
condyle of the femur, being connected by a fibrous expansion to the line leading
upward from the tubercle to the linea aspera. Between the two portions of the
muscle an interval is left, tendinous in front, fleshy behind, for the passage of the
femoral vessels from Hunter's canal into the popliteal space. The external portion
of the muscle at its attachment to the femur presents three or four osseo-aponeurotic
openings, formed by tendinous arches attached to the bone, from which muscular
fibres arise. The three superior of these apertures are for the three perforating
arteries, and the fourth, when it exists, is for the terminal branch of the profunda.
Relations. — By its anterior surface, with the Pectineus, Adductor brevis, Ad-
ductor longus, and the femoral and profunda vessels and obturator nerve; by its
posterior surface, with the great sciatic nerve, the Gluteus maximus, Biceps, Semi-
tendinosus, and Semimembranosus. By its superior or shortest border it lies
parallel with the Quadratus femoris, the internal circumflex artery passing between
them; by its internal or longest border, with the Gracilis, Sartorius, and fascia
lata; by its external or attached border it is inserted into the femur behind the Ad-
ductor brevis and Adductor longus, which separate it from the Vastus internus,
and in front of the Gluteus maximus and short head of the Biceps, which sep-
arate it from the Vastus externus.
Nerves. The three Adductor muscles and the Gracilis are supplied by the
third and fourth lumbar nerves through the obturator nerve; the Adductor mag-
nus receiving an additional branch from the sacral plexus through the great sciatic.
The Pectineus is supplied by the second, third, and fourth lumbar nerves through
the femoral, and by the accessory obturator, from the third lumbar, when it exists.
Occasionally it receives a branch from the obturator nerve.1
Actions. — The Pectineus and three Adductors adduct the thigh powerfully;
they are especially used in horse exercise, the flanks of the horse being grasped
between the knees by the actions of these muscles. In consequence of the obliquity
of their insertion into the linea aspera they rotate the thigh outward, assisting
the external Rotators, and when the limb has been abducted they draw it inward,
carrying the thigh across that of the opposite side. The Pectineus and Adductor
brevis and longus assist the Psoas and Iliacus in flexing the thigh upon the pelvis.
In progression, also, all these muscles assist in drawing forward the hinder limb.
The Gracilis assists the Sartorius in flexing the leg and rotating it inward; it is
also an adductor of the thigh. If the lower extremities are fixed, these muscles
may take their fixed point from below and act upon the pelvis, serving to maintain
the body in an erect posture, or, if their action is continued, to flex the pelvis
forward upon the femur.
Hunter's Canal (canalis adductorius [Hlinteri]) extends from the apex of Scarpa's
triangle to the opening in the Adductor magnus muscle. The antero-internal
boundary or roof of Hunter's canal is the Sartorius and the aponeurotic expan-
sion from the Adductors to the Vastus internus. It is bounded externally by the
Vastus internus. The Adductor longus and Magnus constitute its floor or the
postero-internal boundary. The canal contains the femoral artery, femoral vein,
the long saphenous nerve, and the nerve to the Vastus internus. The anterior
opening of Hunter's canal is called the hiatus tendinous .
1 Professor Paterson describes the Pectineus as consisting of two incompletely separated strata, of which
the outer or dorsal stratum, which is constant, is supplied by the anterior crural nerve, or in its absence by the
accessory obturator, with which it is intimately related; while the inner or ventral stratum, when present, is
supplied by the obturator nerve. — Journ. of Anat. and Phys., vol. xxvi. p. 43. — ED. of 15th English edition.
THE GLUTEAL REGION
525
Surgical Anatomy. — The Adductor longus is liable to be severely strained in those who ride
much on horseback, or its tendon to be ruptured by suddenly gripping the saddle. Occasionally,
especially in cowboys and cavalry soldiers, the tendon of insertion of the Adductor magnus
may become ossified, constituting the rider's bone.
THE MUSCLES AND FASCI-ffl OF THE HIP.
3. The Gluteal Region (Figs. 346, 347).
Gluteus maximus. Obturator internus.
Gluteus medius. Gemellus superior.
Gluteus minimus. Gemellus inferior.
Pyriformis. Quadratus femoris.
Obturator externus.
Dissection (Fig. 345). — The subject should be turned on its face, a block placed beneath
the pelvis to make the buttocks tense, and the limbs allowed to hang over the end of the table,
with the foot inverted and the thigh abducted. Make an incision through the integument along
the crest of the ilium to the middle of the sacrum, and
thence downward to the tip of the coccyx, and carry a
second incision from that point obliquely downward and
outward to the outer side of the thigh, four inches be-
low the great trochanter. The portion of integument
included between these incisions is to be removed in im x
the direction shown in the figure. jl / \ L Dussection of
Hi/ 1 !\ gluteal region.
The Gluteus Maximus (m.glutaeus maximus)
(Fig. 346), the most superficial muscle in the
gluteal region, is a very broad and thick, fleshy
mass of a quadrilateral shape, which forms the
prominence of the buttock. Its large size is one
of the most characteristic points in the mus-
cular system of man, connected as it is with
the power he has of maintaining the trunk in
the erect posture. In structure the muscle is
remarkably coarse, being made up of muscular
fasciculi lying parallel with one another, and
collected together into large bundles, separated
by deep cellular intervals. It arises from the
superior curved line of the ilium and the por-
tion of bone, including the crest, immediately
above and behind it; from the posterior sur-
face of the lower part of the sacrum, the side of
the coccyx, the aponeurosis of the Erector spinse
muscle, the great sacro-sciatic ligament, and
the fascia covering the Gluteus medius. The
fibres are directed obliquely downward and
outward; those forming the upper and large
portion of the muscle, together with the super-
ficial fibres of the lower portion, terminate in
a thick tendinous lamina, which passes across
the great trochanter and is inserted into the
fascia lata covering the outer side of the thigh ;
the deeper fibres of the lower portion of the muscles are inserted into the rough
line leading from the great trochanter to the linea aspera between the Vastus
externus and Adductor magnus.
313. Back of thigh.
2. Popliteal space.
•^•w - *
4/4- Back of leg.
5. Sole of foot.
FIG. 345. — Dissection of lower extremity.
Posterior view.
526 THE MUSCLES AND FASCIAE
Several synovial bursae are found in relation with this muscle. One of these
(bursa trochanterica m. glutaei maximi), of large size, and generally multilocular,
separates it from the great trochanter. A second (bursa ischiadica m, glutoei
maximi), often wanting, is situated on the tuberosity of the ischium. A third
bursa is found between the tendon of this muscle and the Vastus externus. Two
or three small bursse (bursae glutaeofemorales) are placed between the tendon of
the muscle and the gluteal ridge.
Relations. — By its superficial surface, with a thin fascia, which separates it from
the subcutaneous tissue; by its deep surface, from above downward, with the ilium,
sacrum, coccyx, and great sacro-sciatic ligament, part of the Gluteus medius,
Pyriformis, Gemelli, Obturator internus, Quadratus femoris, the tuberosity of
the ischium, great trochanter, the origin of the Biceps, Semitendinosus, Semimem-
branosus, and Adductor magnus muscles. The superficial part of the gluteal
artery reaches the deep surface of the muscle by passing between the Pyriformis
and the Gluteus medius; the sciatic and internal pudic vessels and nerves and
muscular branches from the sacral plexus issue from the pelvis below the Pyri-
formis. The first perforating artery and the terminal branches of the internal cir-
cumflex artery are also found under cover of the muscle. Its upper border is thin,
and connected with the Gluteus medius by the fascia lata. Its lower border is free
and prominent.
Dissection. — Divide the Gluteus maximus near its origin by a vertical incision carried from
its upper to its lower border; a cellular interval will be exposed, separating it from the Gluteus
medius and External rotator muscles beneath. The upper portion of the muscle is to be alto-
gether detached, and the lower portion turned outward; the loose areolar tissue filling up the
interspace between the trochanter major and tuberosity of the ischium being removed, the parts
already enumerated as exposed by the removal of this muscle will be seen.
The Gluteus Medius (m. glutceus medius} (Fig. 346) is a broad, thick, radiated
muscle, situated on the outer surface of the pelvis. Its posterior third is covered by
the Gluteus maximus ; its anterior two-thirds by the fascia lata, which separates
it from the integument. It arises from the outer surface of the ilium, between the
superior and middle curved lines, and from the outer lip of that portion of the
crest which is between them ; it also arises from the dense fascia, the gluteal aponeu-
rosis, covering its outer surface. The fibres converge to a strong flattened tendon
which is inserted into the oblique line which traverses the outer surface of the
great trochanter. A synovial bursa (bursa trochanterica. m. glutaei medii anterior)
separates the tendon of the muscle from the summit of the great trochanter.
There is frequently a bursa (bursa trochanterica m. glutaei medii posterior) between
the tendons of the Gluteus medius and Pyriformis.
Relations. — By its superficial surface, with the Gluteus maximus behind, the
Tensor fasciae femoris and deep fascia in front; by its deep surface, with the Glu-
teus minimus and the gluteal vessels and superior gluteal nerve. Its anterior border
is blended with the Gluteus minimus. Its posterior border lies parallel with the
Pyriformis, the gluteal vessels intervening.
This muscle should now be divided near its insertion and turned upward, when the Gluteus
minimus will be exposed.
The Gluteus Minimus (m. glutceus minimus) (Fig. 346), the smallest of the
three Glutei, is placed immediately beneath the preceding. It is fan-shaped,
arising from the outer surface of the ilium, between the middle and inferior
curved lines, and behind, from the margin of the great sacro-sciatic notch; the
.fibres converge to the deep surface of a radiated aponeurosis, which, terminating
in a tendon, is inserted into an impression on the anterior border of the great
trochanter.
THE GLUTEAL REGION
527
Relations. — By its superficial
surf ace, -with the Gluteus medius
and the gluteal vessels and supe-
rior gluteal nerve; by its deep
surface, with the ilium, the re-
flected tendon of the Rectus
femoris, and the capsular liga-
ment of the hip-joint. Its ante-
rior margin is blended with the
Gluteus medius; its posterior
margin is in contact and some-
times joined with the tendon of
the Pyriformis. There is a
synovial bursa (bursa m.glutaei
minimi) between the tendon of
the Gluteus minimus and the
great trochanter.
The Pyriformis (m. pirifcr-
mis] (Figs. 346 and 347) is
a flat muscle, pyramidal in
shape, lying almost parallel
with the posterior margin of the
Gluteus medius. It is situated
partly within the pelvis at its
posterior part and partly at the
back of the hip-joint. It arises
from the front of the sacrum
by three fleshy digitations at-
tached to the portions of bone
between the first, second, third,
and fourth anterior sacral fora-
mina, and also from the groove
leading from the foramina: a
few fibres also arise from the
margin of the great sacro-sciatic
foramen and from the anterior
surface of the great sacro-sciatic
ligament. The muscle passes
out of the pelvis through the
great sacro-sciatic foramen, the
upper part of which it fills, and
is inserted by a rounded tendon
into the upper border of the
great trochanter, behind, but
often partly blended with, the
tendon of the Obturator in-
ternus and Gemelli muscles.
Relations. — By its anterior
surface, within the pelvis, with
the Rectum (especially on the
left side), the sacral plexus of
nerves, and the branches of the
internal iliac vessels; external
to the pelvis, with the posterior
Inner hamstring
tendons.
SARTORIUS.
GRACILIS.
SEMITENDINOSUS.
SEMIMEMBRA-
NOSUS.
Outer
hamstring
tendon.
Tibia.
FIG. 346. — Muscles of the hip and thigh.
528 THE MUSCLES AND FASCIA
surface of the ischium and the capsular ligament of the hip-joint ; by its posterior
surface, within the pelvis, with the sacrum, and external to it, with the Gluteus
maximus; by its upper border, with the Gluteus medius, from which it is
separated by the gluteal vessels and superior gluteal nerve; by its lower border,
with the Gemellus superior and Coccygeus, the sciatic vessels and nerves, the
internal pudic vessels and nerve, and muscular branches from the sacral plexus,
passing from the pelvis in the interval between the two muscles. There is
usually a bursa (bursa m. piriformis) between the tendon of the pyriformis and
the ilium.
The Obturator Membrane (membrana obturatoria) (Fig. 215) is a thin layer of
interlacing fibres which closes almost completely the obturator foramen. It is
attached, externally, to the margin of the foramen; internally, to the posterior
surface of the ischio-pubic ramus, below and internal to the margin of the
foramen. It presents at its upper and outer part a small canal, obturator canal
(canalis obturatorius) for the passage of the obturator vessels and nerve. Both
obturator muscles are connected with this membrane.
Dissection. — The next muscle, as well as the origin of the Pyriformis, can only be seen when
the pelvis is divided and the viscera removed.
The Obturator Interims (Figs. 346 and 347) , like the preceding muscle, is situated
partly within the cavity of the pelvis, and partly at the back of the hip-joint. It arises
from the inner surface of the anterior and external wall of the pelvis, where it sur-
rounds the greater part of the obturator foramen, being attached to the descending
ramus of the os pubis and the ramus of the ischium, and at the side to the inner sur-
face of the innominate bone below and behind the pelvic brim, reaching from the
upper part of the great sacro-sciatic foramen above and behind to the obturator
foramen below and in front. It also arises from the inner surface of the obturator
membrane except at its posterior part, from the tendinous arch which completes
the canal for the passage of the obturator vessels and nerve and to a slight extent
from the obturator layer of the pelvic fascia, which covers it. The fibres converge
rapidly, and are directed backward and downward, and terminate in four or five
tendinous bands, which are found on its deep surface; these bands are reflected at
a right angle over the inner surface of the tuberosity of the ischium, which is
grooved for their reception; the groove is covered with cartilage, and lined by a
synovial bursa (bursa m. obturatoris interni). The muscle leaves the pelvis by
the lesser sacro-sciatic foramen ; and the tendinous bands unite into a single flat-
tened tendon, which passes horizontally outward, and, after receiving the attach-
ment of the Gemelli, is inserted into the forepart of the inner surface of the great
trochanter in front of the Obturator externus. A synovial bursa, narrow and
elongated in form, is usually found between the tendon of this muscle and the
capsular ligament of the hip: it occasionally communicates with the bursa
between the tendon and the tuberosity of the ischium, the two forming a
single sac.
In order to display the peculiar appearances presented by the tendon of this muscle, it must
be divided near its insertion and reflected inward.
Relations. — Within the pelvis this muscle is in relation, by its anterior surface,
with the obturator membrane and inner surface of the anterior wall of the pelvis ;
by its posterior surface, with the pelvic and obturator fascise, which separate it
from the Levator ani; and it is crossed by the internal pudic vessels and nerve.
This surface forms the outer boundary of the ischio-rectal fossa (Fig. 337).
External to the pelvis it is covered by the Gluteus maximus, is crossed by the
great sciatic nerve, and rests on the back part of the hip-joint. As the tendon
of the Obturator internus emerges from the lesser sacro-sciatic foramen it is over-
THE GLUTEAL REGION
529
lapped by the two Gemelli, while nearer its insertion the Gemelli pass in front of it
and form a groove in which the tendon lies.
The Gemelli (Fig. 346) are two small muscular fasciculi, accessories to the
tendon of the Obturator internus, which is received into a groove between them.
They are called superior and inferior.
The Gemellus Superior, the smaller of the two, arises from the outer surface
of the spine of the ischium, and, passing horizontally outward, becomes blended
SACRO-SPINAL
LIGAMENT WITH
COCCYGEUS Mfll!
MUSCLE
1-iG. 347. — Muscles of the small or true pelvis on the right side, viewed from without and below. (Spalteholz.)
with the upper part of the tendon of the Obturator internus, and is inserted with
it into the inner surface of the great trochanter. This muscle is sometimes wanting.
Relations. — By its superficial surface, with the Gluteus maximus and the sciatic
vessels and nerves; by its deep surface, with the capsule of the hip-joint; by its
34
530
THE MUSCLES AND FASCIAE
upper border, with the lower margin of the Pyriformis; by its lower border, with
the tendon of the Obturator internus.
The Gemellus Inferior arises from the upper part of the tuberosity of the ischium,
where it forms the lower edge of the groove for the Obturator internus tendon,
and, passing horizontally outward, is blended with the lower part of the tendon
of the Obturator internus, and is inserted with it into the inner surface of the great
trochanter.
Relations. — By its superficial surface, with the Gluteus maximus and the sciatic
vessels and nerves; by its deep surface, with the scapular ligament of the hip-joint;
by its upper border, with the tendon of the Obturator internus ; by its lower border,
with the tendon of the Obturator externus and Quadratus femoris.
The Quadratus Femoris (Fig. 346) is a short, flat muscle, quadrilateral in shape
(hence its name), situated between the Gemellus inferior and the upper margin
of the Adductor magnus. It arises from the upper part of the external lip of the
tuberosity of the ischium, and, proceeding horizontally outward, is inserted into
the upper part of the linea quadrata; that is, the line which crosses the posterior
intertrochanteric line. A synovial bursa is often found between the under surface
of this muscle and the lesser trochanter, which it covers.
Obturator
artery.
Anterior division of
obturator nerve.
Anterior inferior
iliac spine.
Posterior division
of obturator
nerve.
Internal circum-
flex artery.
'apsular liga-
ment partly
cut away.
FIG. 348. — Obturator externus muscle. (From a preparation in the Museum of the Royal College of
Surgeons of England.)
Relations. — By its posterior surface, with the Gluteus maximus and the sciatic
vessels and nerves ; by its anterior surface, with the tendon of the Obturator exter-
nus and trochanter minor and with the capsule of the hip-joint; by its upper
border, with the Gemellus inferior. Its lower border is separated from the Adductor
magnus by the terminal branches of the internal circumflex vessels.
Dissection. — In order to expose the next muscle (the Obturator externus) it is necessary
to remove the Psoas, Iliacus, Pectineus, and Adductor brevis and longus muscles from the front
THE GLUTEAL REGION 531
and inner side of the thigh, and the Gluteus maximus and Quadratus femoris from the back
part. Its dissection should, consequently, be postponed until the muscles of the anterior and
internal femoral regions have been explained.
The Obturator Extermis (Figs. 347 and 348) is a flat, triangular muscle, which
covers the outer surface of the anterior wall of the pelvis. It arises from the margin
of bone immediately around the inner side of the obturator foramen — viz., from the
body and ramus of the os pubis and the ramus of the ischium ; it also arises from
the inner two-thirds of the outer surface of the obturator membrane, and from
the tendinous arch which completes the canal for the passage of the obturator
vessels and nerves. The fibres from the pubic arch extend on to the inner sur-
face of the bone, from which they obtain a narrow origin between the margin of
the foramen and the attachment of the membrane. The fibres converging
pass backward, outward, and upward, and terminate in a tendon which runs
across the back part of the hip-joint, and is inserted into the digital fossa of the
femur.
Relations. — By its anterior surface, with the Psoas, Iliacus, Pectineus, Adductor
magnus, and Adductor brevis; and more externally, with the neck of the femur
and capsule of the hip-joint. The obturator artery and vein lie between this
muscle and the obturator membrane; the superficial part of the obturator nerve
lies above the muscle, and the deep branch perforates it; by its posterior surface,
with the obturator membrane and Quadratus femoris.
Nerves. — The Gluteus maximus is supplied by the fifth lumbar and first and
second sacral nerves through the inferior gluteal nerve from the sacral plexus;
the Gluteus medius and minimus, by the fourth and fifth lumbar and first sacral
nerves through the superior gluteal; the Pyriformis is supplied by the first and
second sacral nerves; the Gemellus inferior and Quadratus femoris by the last
lumbar and first sacral nerve; the Gemellus superior and Obturator internus by
the fifth lumbar and first and second sacral nerves, and the Obturator externus
by the second, third, and fourth lumbar nerves through the obturator.
Actions. — The Gluteus maximus, when it takes its fixed point from the pelvis,
extends the femur and brings the bent thigh into a line with the body. Taking
its fixed point from below, it acts upon the pelvis, supporting it and the whole
trunk upon the head of the femur, which is especially obvious in standing on one
leg. Its most powerful actions are to hold the head of the femur in close approxi-
mation to the acetabulum in walking and to cause the body to regain the erect
position after stooping by drawing the pelvis backward, being assisted in this action
by the Biceps, Semitendinosus, and Semimembranosus. The Gluteus maximus
is a tensor of the fascia lata,and by its connection with the ilio-tibial band it steadies
the femur on the articular surface of the tibia during standing, when the Extensor
muscles are relaxed. The lower part of the muscle also acts as an adductor and
external rotator of the limb. The Gluteus medius and minimus abduct the thigh
when the limb is extended, and are principally called into action in supporting
the body on one limb, in conjunction with the Tensor fasciae femoris. Their
anterior fibres, by drawing the great trochanter forward, rotate the thigh inward,
in which action they are also assisted by the Tensor fasciae femoris. The remain-
ing muscles are powerful rotators of the thigh outward. In the sitting posture,
when the thigh is flexed upon the pelvis, their action as rotators cease, and they
become abductors, with the exception of the Obturator externus, which still
rotates the femur outward. When the femur is fixed, the Pyriformis and Obturator
muscles serve to draw the pelvis forward if it has been inclined backward, and
assist in steadying it upon the head of the femur.
Surgical Anatomy. — The fascia over the gluteal region is extremely dense and an abscess
beneath it may pass far down into the thigh.
532
THE MUSCLES AND FASCIA
4. The Posterior Femoral Region.
Biceps. Semitendinosus. Semimembranosus.
(Hamstring muscles.}
Dissection (Fig. 345). — Make a vertical incision along the middle of the back of the thigh,,
from the lower fold of the buttock to about three inches below the back of the knee-joint, and
there connect it with a transverse incision, carried from the inner to the outer side of the leg.
Make a third incision transversely at the junction of the middle with the lower third of the
thigh. The integument having been removed from the back of the knee, and the boundaries
of the popliteal space having been examined, the removal of the integument from the remaining
^>art of the thigh should be continued, when the fascia and muscles of this region will be exposed-
BURSA OF
SEMIMEMBRANOSUS
GASTROCNEMIUS
(inner head)
BURSA OF INNER
HEAD OF
GASTROCNEMIUS
BURSA OF
APONEUROTIC
EXPANSION
OF SARTORIUS
DEEP FASCIA
OF LEG
FIG. 349. — Region of the knee, seen obliquely from behind and within. Right limb. (Toldt.)
The Biceps or Biceps Flexor Cruris (m. biceps femoris) is a large muscle, of
considerable length, situated on the posterior and outer aspect of the thigh
(Figs. 346 and 349). It arises by two heads. One, the long head (caput longum),
arises horn the lower and inner impression on the back part of the tuberosity
THE POSTERIOR FEMORAL REGION 533
of the ischinm, by a tendon common to it and the Semitendinosus, and from
the lower part of the great sacro-sciatic ligament. Between this tendon of
origin and the Semimembranosus there is often a bursa (bursa m. bicipitis
jemoris superior). The femoral, or short head (caput breve), arises from the
outer lip of the linea aspera, between the Adductor magnus and Vastus externus,
extending up almost as high as the insertion of the Gluteus maximus; from
the outer prolongation of the linea aspera to within two inches of the outer con-
el vie, and from the external intermuscular septum. The fibres of the long head
form a fusiform belly, which, passing obliquely downward and a little out-
ward, terminates in an aponeurosis which covers the posterior surface of the
muscle, and receives the fibres of the short head: this aponeurosis becomes
gradually contracted into a tendon, which is inserted into the outer side of the
head of the fibula, and by a small slip into the lateral surface of the external
tuberosity of the tibia. At its insertion the tendon divides into two portions, which
embrace the long external lateral ligament of the knee-joint. From the posterior
border of the tendon a thin expansion is given off to the fascia of the leg. The
tendon of this muscle forms the outer hamstring. Sometimes there is a bursa
(bursa bicipitogastrocnemialis) between the tendon of insertion of the Biceps and
the origin of the Gastrocnemius, and there is a bursa (bursa m. bicipitis femoris
inferior) between the tendon of the biceps and the external lateral ligament.
Relations. — By its superficial surface, with the Gluteus maximus and the small
sciatic nerve, the fascia lata, and integument. By its deep surface, with the Semi-
membranosus, Adductor magnus, and Vastus externus, the great sciatic nerve,
and, near its insertion, with the external head of the Gastrocnemius, the Plantaris,
the superior external articular artery, and the external popliteal nerve.
The Semitendinosus (Figs. 346 and 349), remarkable for the great length
of its tendon, is situated at the posterior and inner aspect of the thigh. It
arises from the lower and inner impression on the tuberosity of the ischium
by a tendon common to it and the long head of the Biceps ; it also arises from
an aponeurosis which connects the adjacent surfaces of the two muscles to
the extent of about three inches after their origin. There is a bursa (bursa
m. bicipitis femoris superior) between the tendons of origin of the Biceps and
Semitendinosus on one side and the tendon of origin of the Semimembranosus
on the other. The Semitendinosus is a fusiform muscle, which, passing down-
ward and inward, terminates a little below the middle of the thigh in a long
round tendon which lies along the inner side of the popliteal space, then
curves around the inner tuberosity of the tibia, and is inserted into the upper
part of the inner surface of the shaft of that bone nearly as far forward as its
anterior border. At its insertion it gives off from its lower border a prolongation
to the deep fascia of the leg. This tendon lies behind the tendon of the Sar-
torius, and below that of the Gracilis, to which it is united. A tendinous inter-
section is usually observed about the middle of the muscles. The bursa anserina
lies between the tendon of the Semitendinosus and the tibia. This bursa was
referred to in speaking of the Gracilis, p. 522.
Relations. — By its superficial surface, with the Gluteus maximus and fascia lata;
by its deep surface, with the Semimembranosus, Adductor magnus, inner head of
the Gastrocnemius, and internal lateral ligament of the knee-joint.
The Semimembranosus (Figs. 346 and 349), so called from its membranous
tendon of origin, is situated at the back part and inner side of the thigh. It
arises by a thick tendon from the upper and outer impression on the back part
of the tuberosity of the ischium, above and to the outer side of the Biceps and
Semitendinosus, and is inserted into the groove on the inner and back part of the
inner tuberosity of the tibia, beneath the internal lateral ligament. The tendon of
the muscle at its origin expands into an aponeurosis which covers the upper part
534 THE MUSCLES AND FASCIAE
of its anterior surface : from this aponeurosis muscular fibres arise, and converge
to another aponeurosis, which covers the lower part of its posterior surface and
contracts into the tendon of insertion. The tendon of the muscle at its insertion
gives off certain fibrous expansions; one of these, of considerable size, passes
upward and outward to be inserted into the back part of the outer condyle of
the femur, forming part of the posterior ligament of the knee-joint; a second is
continued downward to the fascia which covers the Popliteus muscle. The
tendon also sends a few fibres to join the internal lateral ligament of the joint.
The tendons of the two preceding muscles, with that of the Gracilis, form
the inner hamstrings.
Relations. — By its superficial surface, with the Gluteus maximus, Semitendinosus,
Biceps, and fascia lata; by its deep surface, with the origin of the Quadratus
femoris, popliteal vessels, Adductor magnus, and inner head of the Gastroc-
nemius; by its inner border, with the Gracilis; by its outer border, with the great
sciatic nerve, and its internal popliteal branch. There is a bursa between the
Gastrocnemius and Semimembranosus and another bursa between the Semi-
membranosus and the inner condyle of the tibia. The first bursa usually com-
municates with the knee-joint. These two bursae are in communication and in
reality constitute a double bursa (bursa m. semimembranosi) .
Nerves. — The muscles of this region are supplied by the first, second, and
third sacral nerves through the great sciatic nerve.
Actions. — The hamstring muscles flex the leg upon the thigh. When the knee
is semiflexed, the Biceps, in consequence of its oblique direction downward and
outward, rotates the leg slightly outward; and the Semitendinosus, and to a
slight extent the Semimembranosus, rotate the leg inward, assisting the Popliteus.
Taking their fixed point from below, these muscles, especially the Semimem-
branosus, serve to support the pelvis upon the head of the femur and to draV
the trunk directly backward, as in raising it from the stooping position or in
feats of strength, when the body is thrown backward in the form of an arch.
When the leg is extended on the thigh, they limit the amount of flexion of the
trunk on the lower limbs.
Surgical Anatomy. — The hamstring tendons are occasionally ruptured. In disease of the
knee-joint the hamstrings may contract, flexing the knee, drawing the tibia backward, and some-
times causing incomplete dislocation. The tendons of these muscles occasionally require sub-
cutaneous division in some forms of spurious ankylosis of the knee-joint dependent upon
permanent contraction and rigidity of the Flexor muscles, or from stiffening of the ligamentous
and other tissues surrounding the joint, the result of disease. Division of a tendon is effected
by putting the tendon upon the stretch, and inserting a narrow sharp-pointed knife between
it and the skin: the cutting edge being then turned toward the tendon, it should be divided,
taking great care that the wound in the skin is not at the same time enlarged. The relation of the
external popliteal nerve to the tendon of the Biceps must always be borne in mind in dividing this
tendon.
III. MUSCLES AND FASCI-ffi OF THE LEG.
These may be divided into three groups: those on the anterior, those on the
posterior, and those on the outer side of the leg.
5. The Anterior Tibio-fibular Region (Fig. 350).
Tibialis anticus. Extensor longus digitorum.
Extensor proprius hallucis.1 Peroneus tertius.
1 There is no such word as ' 'Hallux, -cis." It is the result of some ignorant blunder, copied until it has become
established by usage; it has been thought better, therefore, to retain it. According to Lewis and bhort, the
word is ALLEX, masculine; genitive, ALLICIS, the great toe, and the correct rendering would be Extensor pro-
prius allicis. It is a rare word, and is sometimes spelt, but not so correctly, ' 'Hallex. It is used by Flautus,
in the "Pcenulus," V., v. 31, of a little man, as we might say "a hop-o'-my-thumb.' "Tune hie amator audes
esse, allex viri" (To think of you daring to make up to her, you hop-o'-my-thumb!). The word alex, some-
times spelt "allex," a fish sauce, is probably a different word altogether. It is used by Horace and Fliny.
— ED. of 15th English edition.
THE ANTERIOR TIBIO-FIBULAR REGION 535
Dissection (Fig. 339). — The knee should be bent, a block placed beneath it, and the foot
kept in an extended position ; then make an incision through the integument in the middle line
of the leg to the ankle, and continue it along the dorsum of the foot to the toes. Make a second
incision transversely across the ankle, and a third in the same direction across the bases of the
toes; remove the flaps of integument included between these incisions in order to examine the
deep fascia of the leg.
The Deep Fascia of the Leg (fascia cruris) forms a complete investment to
the muscles, but is not continuous over the subcutaneous surfaces of the bones.
It is continuous above with the fascia lata, receiving an expansion from the tendon
of the Biceps on the outer side, and from the tendons of the Sartorius, Gracilis,
and Semitendinosus on the inner side; in front it blends with the periosteum
covering the subcutaneous surface of the tibia, and with that covering the head
and external malleolus of the fibula; below it is continuous with the annular liga-
ments of the ankle. It is thick and dense in the upper and anterior part of the leg,
and gives attachment, by its deep surface, to the Tibialis anticus and Extensor
longus digitorum muscles, but is thinner behind, where it covers the Gastrocnemius
and Soleus muscles. Over the popliteal space it is much strengthened by trans-
verse fibres which stretch across from the inner to the outer hamstring muscles,
and it is here perforated by the external saphenous vein. Its deep surface gives
off, on the outer side of the leg, two strong intermuscular septa which enclose the
Peronei muscles, and separate them from the muscles of the anterior and posterior
tibial regions. It also gives off several smaller and more slender processes
which enclose the individual muscles in each region; at the same time a broad
transverse intermuscular septum, called the deep transverse fascia of the leg,
intervenes between the superficial and deep muscles in the posterior tibio-fibular
region.
Remove the fascia by dividing it in the same direction as the integument, excepting opposite
the ankle, where it should be left entire. Commence the removal of the fascia from below,
opposite the tendons, and detach it in the line of direction of the muscular fibres.
The Tibialis Anticus (m. tibialis anterior) is situated on the outer side of the
tibia; it is thick and fleshy at its upper part, tendinous below. It arises from the
outer tuberosity and upper two-thirds of the external surface of the shaft of the
tibia; from the adjoining part of the interosseous membrane; from the deep
surface of the fascia; and from the intermuscular septum between it and the
Extensor longus digitorum: the fibres pass vertically downward, and terminate
in a tendon which is apparent on the anterior surface of the muscle at the lower
third of the leg. After passing through the innermost compartment of the anterior
annular ligament, it is inserted into the inner and under surface of the internal
cuneiform bone and base of the metatarsal bone of the great toe. There is
usually a bursa (bursa subtendinea m. tibialis anterioris) between the tendon of
the tibialis anticus and the internal cuneiform bone.
Relations. — By its anterior surface, with the fascia and with the annular liga-
ment; by its posterior surface, with the interosseous membrane, tibia, ankle-joint,
and inner side of the tarsus : .this surface also overlaps the anterior tibial vessels
and nerve in the upper part of the leg. By its inner surface, with the tibia; by
its outer surface, with the Extensor longus digitorum and Extensor proprius
hallucis, and the anterior tibial vessels and nerve.
The Extensor Proprius Hallucis (m. extensor hallucis longus) is a thin, elon-
gated, and flattened muscle situated between the Tibialis anticus and Extensor
longus digitorum. It arises from the anterior surface of the fibula for about the
middle two-fourths of its extent, its origin being internal to that of the Extensor
longus digitorum; it also arises from the interosseous membrane to a similar
extent. The fibres pass downward, and terminate in a tendon which occupies
536
\TiAu
'jtjainetit.
THE MUSCLES AND FASCIAE
the anterior border of the muscle, passes through a
distinct compartment in the lower portion of the
annular ligament, crosses the anterior tibial vessels
near the bend of the ankle, and is inserted into the
base of the last phalanx of the great toe. Opposite
the metatarso-phalangeal articulation the tendon
gives off a thin prolongation on each side, which
covers the surface of the joint. It usually sends an
expansion from the inner side of the tendon, to be
inserted into the base of the first phalanx.
Relations. — By its anterior surface, with the fascia
and the anterior annular ligament; by its posterior
surface, with the interosseous membrane, fibula,
tibia, and ankle-joint; by its outer side, with the
Extensor longus digitorum above, the dorsalis pedis
vessels, anterior tibial nerve, and Extensor brevis
digitorum below; by its inner side, with the Tibialis
anticus and the anterior tibial vessels above. The
muscle is external to the anterior tibial vessels in
the upper part of the leg; but in the lower third its
tendon crosses over them, so that it lies internal to
them on the dorsum of the foot.
The Extensor Longus Digitorum (m. extensor
digitorum longus} is an elongated, flattened, penni-
form muscle situated the most externally of all the
muscles on the forepart of the leg. It arises from
the outer tuberosity of the tibia; from the upper
three-fourths of the anterior surface of the shaft of
the fibula; from the interosseous membrane; from
th*1 d^ep surface of the fascia; and from the inter-
muscular septa between it and the Tibialis anticus
on the inner and the Peronei on the outer side.
The tendon enters a canal in the annular ligament
with the Peroneus tertius, and divides into four
slips, which run across the dorsum of the foot ancl
are inserted into the second and third phalanges of
the four lesser toes. The mode in which the tendons
are inserted is the following: Each of the three
tendons opposite the metatarso-phalangeal
inner
FIG. 350. — Muscles of the front of
the leg.
articulation is joined, on its outer side, by a ten-
don from the Extensor brevis digitorum. The outer
tendon does not receive such a tendinous slip. They
all receive a fibrous expansion from the Interossei
and Lumbricales, and then spread out into a broad
aponeurosis, which covers the dorsal surface of the
first phalanx: this aponeurosis, at the articulation of
the first with the second phalanx, divides into three
slips — a middle one, which is inserted into the base
of the second phalanx, and two lateral slips, which,
after uniting on the dorsal surface of the second
phalanx, are continued onward, to be inserted into
the base of the third.
Relations. — By its anterior surface, with the fascia
and the annular ligament; by its posterior surface,
THE POSTERIOR TIBIO-FIBULAR REGION 537
with the fibula, interosseous membrane, ankle-joint, and Extensor brevis digi-
torum; by its inner side, with the Tibialis anticus, Extensor proprius hallucis,
and anterior tibial vessels and nerve; by its outer side, with the Peroneus longus
and brevis.
The Peroneus Tertius (m. peronceus tertius) is a part of the Extensor longus
digitorum, and might be described as its fifth tendon. The fibres belonging to
this tendon arise from the lower fourth of the anterior surface of the fibula, from
the lower part of the interosseous membrane, and from an intermuscular septum
between it and the Peroneus brevis. The tendon, after passing through the same
canal in the annular ligament as the Extensor longus digitorum, is inserted into
the dorsal surface of the base of the metatarsal bone of the little toe. This
muscle is sometimes wanting.
Nerves. — These muscles are supplied by the fourth and fifth lumbar and first
sacral nerves through the anterior tibial nerve.
Actions. — The Tibialis anticus and Peroneus tertius are the direct flexors of the
foot at the ankle-joint; the former muscle, when acting in conjunction with the
Tibialis posticus, raises the inner border of the foot (i.e., inverts the foot); and
the latter, acting with the Peroneus brevis and longus, draws the outer border of
the foot upward and the sole outward (i. e., everts the foot). The Extensor longus
digitorum and Extensor proprius hallucis extend the phalanges of the toes, and,
continuing their action, flex the foot upon the leg. Talcing their fixed point from
below, in the erect posture, all these muscles serve to fix the bones of the leg in the
perpendicular position, and give increased strength to the ankle-joint.
6. The Posterior Tibio-fibular Region (Figs. 349, 352).
Dissection (Fig. 345). — Make a vertical incision along the middle line of the back of the
leg, from the lower part of the popliteal space to the heel, connecting it below by a transverse
incision extending between the two malleoli; the flaps of integument being removed, the fascia
and muscles should be examined.
The muscles in this region of the leg are subdivided into two layers — superficial
and deep. The superficial layer constitutes a powerful muscular mass, forming
the calf of the leg. Their large size is one of the most characteristic features of
the muscular apparatus in man, and bears a direct connection with his ordinary
attitude and mode of progression.
The Superficial Layer.
Gastrocnemius. Soleus. Plantaris.
The Gastrocnemius is the most superficial muscle, and forms the greater part
of the calf. It arises by two heads, which are connected to the condyles of the femur
by two strong flat tendons. The inner and larger head (caput mediate) arises from
a depression at the upper and back part of the inner condyle and from the
adjacent part of the femur. There is a bursa (bursa m. gastrocnemii medialis)
between the tendon of origin and the inner condyle. The outer head (caput
laterale) arises from an impression on the outer side of the external condyle and
from the posterior surface of the femur immediately above the condyle. There
is a bursa (bursa m. gastrocnemii lateralis) between the tendon of origin and the
outer condyle. Both heads, also, arise by a few tendinous and fleshy fibres
from the ridges which are continued upward from the condyles to the linea aspera.
Each tendon spreads out into an aponeurosis, which covers the posterior surface
of that portion of the muscle to which it belongs; the muscular fibres of the
inner head being thicker and extending lower than those of the outer. From
the anterior surface of these tendinous expansions muscular fibres are given off.
538
THE MUSCLES AND FASCIAE
The fibres in the median line, which correspond to the accessory portions of the
muscle derived from the bifurcations of the linea aspera, unite at an angle
upon a median tendinous raphe below: the remaining fibres converge to an
aponeurosis which covers the anterior surface of the muscle, and this, gradually
contracting, unites with the tendon of the Soleus, and forms with it the tendo
Achillis.
Relations. — By its superficial surface, with the fascia of the leg, which separates
it from the external saphenous vein and nerve; by its deep surface, with the pos-
terior ligament of the knee-joint, the Popliteus, Soleus, Plantaris, popliteal vessels,
and internal popliteal nerve. The tendon of the inner head corresponds with the
back part of the inner condyle, from which it is separated by a synovial bursa,
which, in some cases, communicates with the cavity of the knee-joint. The
tendon of the outer head contains a sesamoid fibro-cartilage '(rarely osseous)
where it plays over the corresponding outer condyle; and one is occasionally
found in the tendon of the inner head.
The Gastrocnemius should be divided across, just below its origin, and turned downward,
in order to expose the next two muscles.
The Soleus is a broad flat muscle situated immediately beneath the Gastroc-
nemius. It has received its name from its resemblance in shape to a sole-fish. It
arises by tendinous fibres from the back part of the head of the fibula and from
the upper third of the posterior surface of its shaft;
from the oblique line of the tibia and from the mid-
dle third of its internal border; some fibres also arise
from a tendinous arch placed between the tibial and
fibular origins of the muscle, beneath which the
popliteal vessels and internal popliteal nerve pass.
The fibres pass backward to an aponeurosis which
covers the posterior surface of the muscle, and this,
gradually becoming thicker and narrower, joins with
the tendon of the Gastrocnemius, and forrhs with it
the tendo Achillis.
The triceps surce is the designation in the new
nomenclature of the Gastrocnemius and Soleus.
Relations. — By its superficial surface, with the
Ga.strocnemius and Plantaris; by its deep surface,
with the Flexor longus digitorum, Flexor longus
hallucis, Tibialis posticus, and posterior tibial
vessels and nerve, from which it is separated by
the transverse intermuscular septum or deep transverse fascia of the leg.
The Tendo Achillis (tendo cakaneus], the common tendon of the Gastrocnemius
and Soleus,1 is the thickest and strongest tendon in the body. It is about six
inches in length, and commences about the middle of the leg, but receives fleshy
fibres on its anterior surface nearly to its lower end. Gradually becoming con-
tracted below, it is inserted into the lower part of the posterior surface of the
os calcis, a synovial bursa, the retro-calcaneal bursa (bursa tendinis calcanei
[Achillis]) (Fig. 351), being interposed between the tendon and the upper part
of this surface. The tendon spreads out somewhat at its lower end, so that its
narrowest part is usually about an inch and a half above its insertion. The tendon
is covered by the fascia and the integument, a bursa (bursa subcutanea calcanea)
(Fig. 351) being often interposed between the tendon and the fascia. The tendon
BURSA BETWEEN
FASCIA AND
TENDON
BURSA BETWEEN
TENDON AND
OS CALCIS
FIG. 351. — Bursse of the tendo
Achillis. (Poirier and Charpy.)
1 These two muscles with a common tendon are by some anatomists classed together as one muscle, the
Triceps sura, the two heads of origin of the Gastrocnemius and the Soleus constituting the three heads of the
Triceps, and the tendo Achillis the single tendon of insertion. — ED. of 15th English edition.
THE POSTERIOR TIBIO-FIBULAR REGION
539
is separated from the deep muscles and vessels by a considerable interval filled
up with areolar and adipose tissue. Along its outer side, but superficial to it, is
the external saphenous vein.
' Femur. \
Tendons of
fpERONEUS LONGUS
and BREVIS.
FIG. 352. — Muscles of the back of the leg.
Superficial layer.
FIG. 353. — Muscles of the back
of the leg. Deep layer.
The Plantaris is an extremely diminutive muscle placed between the Gas-
trocnemius and Soleus, and remarkable fof its long and delicate tendon. It arises
540 THE MUSCLES AND FASCIAE
from the lower part of the outer prolongation of the linea aspera and from the pos-
terior ligament of the knee-joint. It forms a small fusiform belly, about three or
four inches in length, terminating in a long slender tendon which crosses obliquely
between the two muscles of the calf, and, running along the inner border of the
tendo Achillis, is inserted with it into the posterior part of the os calcis. This
muscle is occasionally double, and is sometimes wanting. Occasionally its tendon
is lost in the internal annular ligament or in the fascia of the leg.
Nerves. — The Gastrocnemius is supplied by the first and second sacral nerves,
and the Plantaris by the fourth and fifth lumbar and first sacral nerves through the
internal popliteal. The Soleus is supplied by the fifth lumbar and first and second
sacral nerves through the internal popliteal and posterior tibial.
Actions. — The muscles of the calf are the chief extensors of the foot at the
ankle-joint. They possess considerable power, and are constantly called into use
in standing, walking, dancing, and leaping; hence the large size they usually pre-
sent. In walking these muscles draw powerfully upon the os calcis, raising the
heel, and with it the entire body, from the ground; the body being thus supported
on the raised foot, the opposite limb can be carried forward. In standing, the
Soleus, taking its fixed point from below, steadies the leg upon the foot, and pre-
vents the body from falling forward, to which there is a constant tendency from the
.superincumbent weight. The Gastrocnemius, acting from below, serves to flex the
femur upon the tibia, assisted by the Popliteus. The Plantaris is the rudiment of
a large muscle which exists in some of the lower animals and is continued over the
os calcis to be inserted into the plantar fascia. In man it is an accessory to the
Gastrocnemius, extending the ankle if the foot is free, or bending the knee if the
foot is fixed. Possibly, acting from below, by its attachment to the posterior liga-
ment of the knee-joint, it may pull that ligament backward during flexion, and so
protect it from being compressed between the two articular surfaces.
The Deep Layer (Fig. 353).
Popliteus. Flexor longus digitorum.
Flexor longus hallucis. Tibialis posticus.
>
Dissection. — Detach the Soleus from its attachment to the fibula and tibia, and turn it down-
ward, when the deep layer of muscles is exposed, covered by the deep transverse fascia of the
leg.
Deep Transverse Fascia. — The deep transverse fascia of the leg is a trans-
versely placed, intermuscular septum, between the superficial and deep muscles
in the posterior tibio-fibular region. On either side it is connected to the margins
of the tibia and fibula. Above, where it covers the Popliteus, it is thick and dense,
and receives an expansion from the tendon of the Semimembranosus ; it is thinner
in the middle of the leg, but below, where it covers the tendons passing behind the
malleoli, it is thickened and continuous with the internal annular ligament.
This fascia should now be removed, commencing from below opposite the tendons, and
detaching it from the muscles in the direction of their fibres.
The Popliteus (Fig. 349) is a thin, flat, triangular muscle, which forms part of
the floor of the popliteal space. It arises by a strong tendon, about an inch in
length, from a deep depression on the outer side of the external condyle of the
femur, and from the posterior ligament of the knee-joint. A bursa (bursa m.
poplitei) is placed between the condyle and the muscle. The muscle is inserted
into the inner two-thirds of the triangular surface above the oblique line on the
posterior surface of the shaft of the tibia, and into the tendinous expansion
covering the surface of the muscle. The tendon of the muscle is covered by
that of the Biceps and by the external lateral ligament of the knee-joint; it grooves
THE POSTERIOR TIBIO-FIB ULAR REGION 541
the posterior border of the external semilunar fibro-cartilage, and is invested by
the synovial membrane of the knee-joint.
Relations. — By its superficial surface, with the fascia covering it, which separates
it from the Gastrocnemius, Plantaris, popliteal vessels, and internal popliteal nerve;
by its deep surface, with the knee-joint and back of the tibia.
The Flexor Longus Hallucis (m. flexor hallucis longus) is situated on the fibular
side of the leg, and is the most superficial and largest of the three next muscles.
It arises from the lower two-thirds of the posterior surface of the shaft of the
fibula, with the exception of an inch at its lowest part; from the lower part of
the interosseous membrane; from an intermuscular septum between it and the
Peronei, externally; and from the fascia covering the Tibialis posticus internally.
The fibres pass obliquely downward and backward, and terminate in a tendon
which occupies nearly the whole length of the posterior surface of the muscle.
This tendon occupies a groove on the posterior surface of the lower end of the
tibia; it then lies in a second groove on the posterior surface of the astragalus, and
finally in a third groove, beneath the sustentaculum tali of the os calcis, and
passes into the sole of the foot, where it runs forward between the two heads of
the Flexor brevis hallucis, and is inserted into the base of the last phalanx of the
great toe (Fig. 355). The grooves in the astragalus and os calcis, which contain
the tendon of the muscle, are converted by tendinous fibres into distinct canals
lined by synovial membrane; and as the tendon crosses the sole of the foot, it is
connected to the common flexor by a tendinous slip.
Relations. — By its superficial surface, with the Soleus and tendo Achillis, from
which it is separated by the deep transverse fascia; by its deep surface, with the
fibula, Tibialis posticus, the peroneal vessels,, the lower part of the interosseous
membrane, and the ankle-joint; by its outer border, with the Peronei; by its inner
border, with the Tibialis posticus and posterior tibial vessels and nerve. In the
sole of the foot it lies above the Abductor hallucis and Flexor longus digitorum.
The Flexor Longus Digitorum (m. flexor digitorum longus) is situated on
the tibial side of the leg. At its origin it is thin and pointed, but gradually
.increases in size as it descends. It arises from the posterior surface of the shaft
of the tibia, immediately below the oblique line to within three inches of its
extremity, internal to the tibial origin of the Tibialis posticus; some fibres also
arise from the fascia covering the Tibialis posticus. The fibres terminate in a
tendon which runs nearly the whole length of the posterior surface of the muscle.
This tendon passes behind the internal malleolus in a groove, common to it and
the Tibialis posticus, but separated from the latter by a fibrous septum, each
tendon being contained in a special sheath lined by a separate synovial membrane.
It then passes obliquely forward and outward, superficial to the internal lateral
ligament, into the sole of the foot (Fig. 355), where, crossing superficially to the
tendon of the Flexor longus hallucis,1 to which it is connected by a strong
tendinous slip, it becomes expanded, is joined by the Flexor accessorius, and finally
divides into four tendons which are inserted into the bases of the last phalanges
of the four lesser toes, each tendon passing through a fissure in the tendon of the
Flexor brevis digitorum opposite the base of the first phalanges (Fig. 354).
Relations. — In the leg: by its superficial surface, with the posterior tibial vessels
and nerve, and the deep transverse fascia, which separates it from the Soleus
mliscle; by its deep surface, with the Tibia and Tibialis posticus. In the foot it is
covered by the Abductor hallucis and Flexor brevis digitorum, and crosses super-
ficial to the Flexor longus hallucis.
The Tibialis Posticus (m. tibialis posterior) lies between the two preceding
muscles, and is the most deeply seated of all the muscles in the leg. It com-
1 That is, in the order of dissection of the sole of the foot.
542 THE MUSCLES AND FASCIAE
mences above by two pointed processes, separated by an angular interval,
through which the anterior tibial vessels pass forward to the front of the leg.
It arises from the whole of the posterior surface of the interosseous membrane,
excepting its lowest part, from the outer portion of the posterior surface of the
shaft of the tibia, between the commencement of the oblique line above, and the
junction of the middle and lower third of the shaft below; and from the upper
two-thirds of the internal surface of the fibula; some fibres also arise from the
deep transverse fascia and from the intermuscular septa, separating it from the
adjacent muscles on each side. This muscle, in the lower fourth of the leg,
passes in front of the Flexor longus digitorum, and terminates in a tendon which
passes' through a groove behind the inner malleolus with the tendon of that
muscle, but enclosed in a separate sheath; it then passes through another sheath,
over the internal lateral ligament into the foot, and then beneath the inferior
calcaneo-scaphoid ligament, and is inserted into the tuberosity of the scaphoid
and internal cuneiform bones (Fig. 356). The tendon of this muscle contains a
sesamoid fibro-cartilage as it passes over the scaphoid bone, and gives off fibrous
expansions, one of which passes backward to the sustentaculum tali of the os calcis,
others outward to the middle and external cuneiform and cuboid, and some
forward to the base of the second, third, and fourth metatarsal bones (Fig. 355).
Relations. — By its superficial surface, with the Soleus, from which it is separated
by the deep transverse fascia, the Flexor longus digitorum, the posterior tibial
vessels and nerve, and the peroneal vessels; by its deep surface, with the inter-
osseous ligament, the tibia, fibula, and ankle-joint.
Nerves. — The Popliteus is supplied by the fourth and fifth lumbar and first sacral
nerves, through the internal popliteal; the Flexor longus digitorum and Tibialis
posticus by the fifth lumbar and first sacral; and the Flexor longus hallucis by the
fifth lumbar and first and second sacral nerves through the posterior tibial.
Actions. — The Popliteus assists in flexing the leg upon the thigh; when the leg
is flexed, it will rotate the tibia inward. It is especially called into action at the
commencement of the act of bending the knee, inasmuch as it produces a slight
inward rotation of the tibia, which is essential in the early stage of this movement..
The Tibialis posticus is a direct extensor of the foot at the ankle-joint; acting in
conjunction with the Tibialis anticus, it turns the sole of the foot inward (i. e.,
inverts the foot), antagonizing the Peronei, which turn it outward (evert it). In
the sole of the foot the tendon of the Tibialis posticus lies directly below the inferior
calcaneo-scaphoid ligament, and is therefore an important factor in maintaining
the arch of the foot. The Flexor longus digitorum and Flexor longus hallucis are
the direct flexors of the phalanges, and, continuing their action, extend the foot
upon the leg; they assist the Gastrocnemius and Soleus in extending the foot, as in
the act of walking or in standing on tiptoe. In consequence of the oblique direction
of the tendon of the long flexor the toes would be drawn inward were it not for the
Flexor accessorius muscle, which is inserted into the outer side of its tendon and
draws it to the middle line of the foot during its action. Taking their fixed point
from the foot, these muscles serve to maintain the upright posture by steadying
the tibia and fibula perpendicularly upon the ankle-joint. They also serve to raise
these bones from the oblique position they assume in the stooping posture.
7. The Fibular Region (Fig. 353).
Peroneus longus. Peroneus brevis.
Dissection. — The muscles are readily exposed by removing the fascia covering their surface,
from below upward, in the line of direction of their fibres.
The Peroneus Longus (m. peronceus longus) is situated at the upper part of
the outer side of the leg, and is the more superficial of the two muscles. It arises
THE FIBULAR REGION 543
from the head and upper two-thirds of the outer surface of the shaft of the fibula,
from the deep surface of the fascia, and from the intermuscular septa between it
and the muscles on the front, and those on the back of the leg, occasionally also
by a few fibres from the outer tuberosity of the tibia. Between its attachment
to the head and to the shaft of the fibula there is a small interval of bone from
which no muscular fibres arise ; through this gap the external popliteal nerve passes
beneath the muscle. The muscle terminates in a long tendon, which passes behind
the outer malleolus, in a groove common to it and the tendon of the Peroneus
brevis, behind which it lies, the groove being converted into a canal by a fibrous
band, and the tendons being invested by a common synovial membrane; it is
then reflected obliquely forward across the outer side of the os calcis, below its
peroneal tubercle, being contained in a separate fibrous sheath, lined by a pro-
longation of the synovial membrane which lines the groove behind the malleolus.
Having reached the outer side of the cuboid bone, it runs in a groove on the
under surface of that bone, which is converted into a canal by the long calcaneo-
cuboid ligament, and is lined by a synovial membrane: the tendon then crosses
the sole of the foot obliquely, and is inserted into the outer side of the base of the
metatarsal bone of the great toe and the internal cuneiform bone (Figs. 355 and
356). Occasionally it sends a slip to the base of the second metatarsal bone. The
tendon changes its direction at two points: first, behind the external malleolus;
secondly, on the outer side of the cuboid bone; in both of these situations the
tendon is thickened, and in the latter a sesamoid fibre-cartilage, or sometimes a
bone, is usually developed in its substance.
Relations. — By its superficial surface, with the fascia and integument; by its
deep surface, with the fibula, external popliteal nerve, the Peroneus brevis, os
calcis, and cuboid bone; by its anterior border, with an intermuscular septum,,
which intervenes between it and the Extensor longus digitorum; by its posterior
border, with an intermuscular septum, which separates it from the Soleus above
and the Flexor longus hallucis below.
The Peroneus Brevis (m. peronaeus brevis} lies beneath the Peroneus longus,
and is shorter and smaller than it. It arises from the lower two-thirds of the
external surface of the shaft of the fibula, internal to the Peroneus longus, and
from the intermuscular septa separating it from the adjacent muscles on the front
and back part of the leg. The fibres pass vertically downward, and terminate in
a tendon which runs in front of that of the preceding muscle through the same
groove, behind the external malleolus, being contained in the same fibrous
sheath and lubricated by the same synovial membrane. It then passes through
a separate sheath on the outer side of the os calcis, above that for the tendon of
the Peroneus longus, the two tendons being here separated by the peroneal
tubercle, and is finally inserted into the tuberosity at the base of the metatarsal
bone of the little toe, on its outer side.
Relations. — By its superficial surface, with the Peroneus longus and the fascia
of the leg and foot; by its deep surface, with the fibula and outer side of the os
calcis.
Nerves. — The Peroneus longus and brevis are supplied by the fourth and fifth
lumbar and first sacral nerves through the musculo-cutaneous branch of the
external popliteal nerve.
Actions. — The Peroneus longus and brevis extend the foot upon the leg, in
conjunction with the Tibialis posticus, antagonizing the Tibialis anticus and
Peroneus tertius, which are flexors of the foot. The Peroneus longus also everts
the sole of the foot; hence the extreme eversion occasionally observed in fracture
of the lower end of the fibula, where that bone offers no resistance to the action
of this muscle. From the oblique direction of the Peroneus longus tendon across
the sole of the foot it is an important agent in the maintenance of the transverse
544 THE MUSCLES AND FASCIAE
arch of the foot. Taking their fixed point below, the Peronei serve to steady the
leg upon the foot. This is especially the case in standing upon one leg, when
the tendency of the superincumbent weight is to throw the leg inward: the
Peroneus longus overcomes this tendency by drawing on the outer side of the
leg, and thus maintains the perpendicular direction of the limb.
Surgical Anatomy. — The student should now consider the position of the tendons of the
various muscles of the leg, their relation with the ankle-joint and surrounding blood-vessels, and
especially their action upon the foot, as their rigidity and contraction give rise to one or other of
the kinds of deformity known as club-foot. The most simple and common deformity, and one
that is rarely, if ever, congenital, is the talipes cquinus, the heel being raised by rigidity and con-
traction of the Gastrocnemius muscle, and the patient walking upon the ball of the foot. In the
talipes varus the foot is forcibly adducted and the inner side of the sole raised, sometimes to a
right angle with the ground, by the action of the Tibialis anticus and posticus. In the talipes
valgus the outer edge of the foot is raised by the Peronei muscles, and the patient walks on the
inner ankle. In the talipes calcaneus the toes are raised by the Extensor muscles, the heel is
depressed, and the patient walks upon it. Other varieties of deformity are met with, as the
talipes equino-varus, equino-valgus, and calcaneo-valgus, whose names sufficiently indicate their
nature. Of these, the talipes equino-varus is the most common congenital form: the heel is
raised by the tendo Achillis, the inner border of the foot drawn upward by the Tibialis anticus,
the anterior two-thirds twisted inward by the Tibialis posticus, and the arch increased by the
contraction of the plantar fascia, so that the patient walks on the middle of the outer border of
the foot. Each of these deformities may sometimes be successfully relieved by division of the
opposing tendons and fascia; by this means the foot regains its proper position, and the tendons
subsequently heal. The operation is easily performed by putting the contracted tendon upon
the stretch, and dividing it by means of a narrow, sharp-pointed knife inserted beneath it.
Pes cavus or hollow foot is accentuation of the longitudinal arch. Pes planus or flat-foot has-
been discussed elsewhere.
Rupture of a few of the fibres of the Gastrocnemius may take place. Rupture of the Plantaris
tendon not uncommonly occurs, especially in men somewhat advanced in life, from some sudden
exertion, and frequently occurs during the game of lawn tennis, and is hence known as lawn-
tennis leg. The accident is accompanied by a sudden pain, and produces a sensation as if the
individual had been struck a violent blow on the part. The tendo Achillis is also sometimes
ruptured. It is stated that John Hunter ruptured his tendo Achillis whilst dancing at the
age of forty. The retro-calcaneal bursa is interposed between the posterior surface of the os
calcis and the tendo Achillis, just above the point of insertion of the tendon. If it inflames
it produces disabling pain (achillodynia, or A Ibert's disease, retro-calcaneal bursitis) . This bursa
may become cartilaginous or osteophytes may form on the surface toward the os calcis.
IV. MUSCLES AND FASCIA OF THE FOOT.
The fibrous bands, or thickened portions of the fascia of the leg, which bind down the tendons
in front of and behind the ankle in their passage to the foot should now be examined; they are
termed the annular ligaments, and are three in number — anterior, internal, and external.
The Anterior Annular Ligament (Fig. 350) consists of a superior or transverse portion
(ligamentum transversum cruris} which binds down the Extensor tendons as they
descend on the front of the tibia and fibula; and an inferior or Y-shaped portion
(ligamentum' crudatum cruris}, which retains them in connection with the tarsus,
the two portions being connected by a thin intervening layer of fascia. The
transverse portion is attached externally to the lower end of the fibula and inter-
nally to the tibia; above it is continuous with the fascia of the leg; it contains
only one synovial sheath, for the tendon of the Tibialis anticus; the other tendons
and the anterior tibial vessels and nerve passing beneath it, but without any dis-
tinct synovial sheath. The Y-shaped portion is placed in front of the ankle-joint,
the stem of the Y, the fundiform ligament of Retzius, being attached externally to
the upper surface of the os calcis, in front of the depression for the interosseous
ligament; it is directed inward, as a double layer, one lamina passing in front,
and the other behind, the tendons of the Peroneus tertius and Extensor longus
digitorum. At the inner border, of the latter tendon these two layers join 'together,
OF THE FOOT 545
forming a sort of loop or sheath in which the tendons are enclosed, surrounded
by a synovial membrane. From the inner extremity of this loop the two limbs
of the Y diverge: one passes upward and inward, to be attached to the internal
malleolus, passing over the Extensor proprius hallucis and the vessels and nerves,
but enclosing the Tibialis anticus and its synovial sheath by a splitting of its
fibres. The other limb extends downward and inward to be attached to the
inner border of the plantar fascia, and passes over the tendons of the Extensor
proprius hallucis and Tibialis anticus and also the vessels and nerves. These
two tendons are contained in separate synovial sheaths situated beneath the
ligament.
The Internal Annular Ligament (ligamentum laciniatum} is a strong fibrous
band which extends from the inner malleolus above to the internal margin of the
os calcis below, converting a series of grooves in this situation into canals for the
passage of the tendons of the Flexor muscles and vessels into the sole of the foot.
It is continuous by its upper border with the deep fascia of the leg, and by its lower
border with the plantar fascia and the fibres of origin of the Abductor hallucis
muscle. The four canals which the ligament completes transmit, counting from
before backward, first, the tendon of the Tibialis posticus; second, the tendon of the
Flexor longus digitorum; third, the posterior tibia! vessels and nerve, which run
through a broad space beneath the ligament; lastly, in a canal formed partly by
the astragalus, the tendon of the Flexor longus hallucis. The canals for the tendons
are lined by a separate synovial membrane.
The External Annular Ligament is divided into two portions: a superior por-
tion (rctinaculum mm. peronaeorum superius), which extends from the extremity
of the outer malleolus to the outer surface of the os calcis: it binds down the
tendons of the Peroneus longus and brevis muscles in their passage behind the
external malleolus. The two tendons are enclosed in one synovial sac. An
inferior portion (retinaculum mm. peronaeorum inferius), which bridges the Peronei
on the side of the os calcis and is attached to the bone above and below them.
Dissection of the Sole of the Foot.— The foot should be placed on a high block with the
sole uppermost, and firmly secured in that position. Carry an incision round the heel and along
the inner and outer borders of the foot to the great and little toes. This incision should divide
the integument and thick layer of granular fat beneath until the fascia is visible; the skin and fat
should then be removed from the fascia in a direction from behind forward, as seen in Fig. 345.
Plantar Fascia (aponeurosis plantaris). — The plantar fascia, the densest of all
the fibrous membranes, is of great strength, and consists of pearly-white glisten-
ing fibres, disposed, for the most part, longitudinally: it is divided into a central
and two lateral portions.
Central Portion. — The central portion, the thickest, is narrow behind and
attached to the inner tubercle of the os calcis, posterior to the origin of the
Flexor brevis digitorum, and, becoming broader and thinner in front, divides
near the heads of the metatarsal bones into five processes, one for each of the toes.
Each of these processes divides opposite the metatarso-phalangeal articulation
into two strata, superficial and deep. The superficial stratum is inserted into
the skin of the transverse sulcus which divides the toes from the sole. The
deeper stratum divides into two slips which embrace the sides of the flexor tendons
of the toes, and blend with the sheaths of the tendons, and laterally with the
transverse metatarsal ligament, thus forming a series of arches through which
the tendons of the short and long flexors pass to the toes. The intervals left
between the five processes allow the digital vessels and nerves and the' tendons
of the Lumbricales muscles to become superficial. At the point of division of the
fascia into processes and slips numerous transverse fibres are superadded, which
serve to increase the strength of the fascia at this part by binding the processes
35
546 THE MUSCLES AND FASCIAE
together and connecting them with the integument. The central portion of the
plantar fascia is continuous with the lateral portions at each side, and sends
upward into the foot, at their point of junction, two strong vertical intermuscular
septa, broader in front than behind, which separate the middle from the external
and internal plantar group of muscles; from these, again, thinner transverse
septa are derived, which separate the various layers of muscles in this region.
The upper surface of this fascia gives attachment behind to the Flexor brevis
digitorum muscle.
Lateral Portions. — The lateral portions of the plantar fascia are thinner than
the central piece, and cover the sides of the foot. The outer portion covers the
under surface of the Abductor minimi digiti; it is thick behind, thin in front, and
extends from the os calcis, forward, to the base of the fifth metatarsal bone, into
the outer side of which it is attached; it is continuous internally with the middle
portion of the plantar fascia, and externally with the dorsal fascia. The inner
portion is very thin, and covers the Abductor hallucis muscle; it is attached
behind to the internal annular ligament, and is continuous around the side of
the foot with the dorsal fascia, and externally with the middle portion of the
plantar fascia
Bursse about the Ankle and Foot. — (1) A subcutaneous bursa on the sole of
the foot, beneath the tuberosity of the os calcis. (2) A subcutaneous bursa
over the tendo Achillis (bursa subcutanea calcanea). (3) The retrocalcaneal
bursa, between the posterior surface of the os calcis and the insertion of the
tcndo Achillis (bursa tendinis calcanei [Achillis]). (4) A bursa between the
internal cuneiform bone and the tendon of the Tibialis anticus (bursa subten-
dinea m. tibialis anterioris) . (5) Bursae between the heads of the metatarsal
bones (bursae intermetatarsophalangeae). (6) A subcutaneous bursa over the
internal malleolus (bursa subcutanea malleoli medialis). (7) Bursse between the
scaphoid and middle cuneiform bones on the one hand and the tendon of the
Tibialis posticus on the other (bursa subtendinea m. tibialis posteriori*) . (8) Bursse
between the Lumbricales and the transverse ligaments (bursae mm. lumbricalium
pedis) . (9) A bursa over the external malleolus (bursa subcutanea malleoli lateralis).
(10) A bursa over the head of the first metatarsal bone. Various muscles have
tendon-sheaths lined with synovial membrane (vaginal sheaths).
Surgical Anatomy. — The dense plantar fascia aids powerfully in maintaining the arch of the
foot. When this fascia stretches or gives way flat-foot forms. In some forms of club-foot
the plantar fascia is contracted. This contraction is usually a secondary change.
When inflammation causes tenderness and enlargement of the bursa over the metatarso-
phalangeal articulation of the great toe, the enlargement is called a bunion. Enlargement of
the retro-calcaneal bursa is known as Albert's disease, or achillodynia.
8. The Dorsal Region (Fig. 350).
Extensor brevis digitorum.
Fascia (fascia dorsalis pedis). — The fascia on the dorsum of the foot is a thin
membranous layer continuous above with the anterior margin of the annular
ligament; it becomes gradually lost opposite the heads of the metatarsal bones,
and on each side blends with the lateral portions of the plantar fascia ; it forms a
sheath for the tendons placed o'n the dorsum of the foot. On the removal of this
fascia the muscles and tendons of the dorsal region of the foot are exposed.
The Extensor Brevis Digitorum (m. extensor digitorum brevis) (Fig. 350)
is a broad thin muscle which arises from the forepart of the upper and
outer surfaces of the os calcis, in front of the groove for the Peroneus brevis,
from the external calcaneo-astragaloid ligament, and from the common limb of
the Y-shaped portion of the anterior annular ligament. It passes obliquely
THE PLANTAR REGION 547
across the dorsum of the foot, and terminates in four tendons. The innermost,
which is the largest, is inserted into the dorsal surface of the base of the first
phalanx of the great toe, crossing the dorsalis pedis artery; the other three, into
the outer sides of the long extensor tendons of the second, third, and fourth toes.
Relations. — By its superficial surface, with the fascia of the foot, the tendons
of the Extensor longus digitorum and Peroneus tertius; by its deep surface, with
the tarsal and metatarsal arteries and bones and the Dorsal interossei muscles.
Nerves. — It is supplied by the anterior tibial nerve.
Actions. — The Extensor brevis digitorum is an accessory to the long Extensor,
extending the phalanges of the four inner toes, but acting only on the first phalanx
of the great toe. The obliquity of its direction counteracts the oblique movement
given to the toes by the long Extensor, so that, both muscles acting together, the
toes are evenly extended.
9. The Plantar Region (Figs. 354, 355, 356, 357, 358).
The muscles in the plantar region of the foot may be divided into three groups,
in a similar manner to those in the hand. Those of the internal plantar region
are connected with the great toe, and correspond with those of the thumb; those
of the external plantar region are connected with the little toe, and correspond
with those of the little finger; and those of the middle plantar region are con-
nected with the tendons intervening between the two former groups. But in order
to facilitate the dissection of these muscles it will be found more convenient to
divide them into four layers, as they present themselves, in the order in which
they are successively exposed.
The First Layer.
Abductor hallucis. Flexor brevis digitorum.
Abductor minimi digiti.
Dissection. — Remove the fascia on the inner and outer sides of the foot, commencing in
front over the tendons and proceeding backward. The central portion should be divided
transversely in the middle of the foot, and the two flaps dissected forward and backward.
The Abductor Hallucis lies along the inner border of the foot. It arises from
the inner tubercle on the under surface of the os calcis; from the internal annular
ligament ; from the plantar fascia ; and from the intermuscular septum between it
and the Flexor brevis digitorum. The fibres terminate in a tendon which is
inserted, together with the innermost tendon of the Flexor brevis hallucis, into
the inner side of the base of the first phalanx of the great toe.
Relations. — By its superficial surface, with the plantar fascia; by its deep sur-
face, with the Flexor brevis hallucis, the Flexor accessorius, and the tendons of
the Flexor longus digitorum and Flexor longus hallucis, the Tibialis anticus and
posticus, the plantar vessels and nerves. Its outer border is in relation to the
Flexor brevis digitorum.
The Flexor Brevis Digitorum (m. flexor digitorum brevis} lies in the
middle of the sole of the foot, immediately beneath1 the plantar fascia, with
which it is firmly united. It arises by a narrow tendinous process, from the
inner tubercle of the os calcis, from the central part of the plantar fascia, and
from the intermuscular septa between it and the adjacent muscles. It passes
forward, and divides into four tendons, one for each of the four outer toes.
Opposite the bases of the first phalanges each tendon divides into two slips, to
allow of the passage of the corresponding tendon of the Flexor longus digitorum;
1 That is, in order of dissection of the sole of the foot.
548
THE MUSCLES AND FASCIA
the two portions of the tendon then unite and form a grooved channel for the
reception of the accompanying long flexor tendon. Finally, they divide a second
time, to be inserted into the sides of the second phalanges about their middle. The
mode of division of the tendons of the Flexor brevis digitorum and their insertion
into the phalanges is analogous to the division
and insertion of the Flexor sublimis digitorum
in the hand.
Relations. — By its superficial surface, with
the plantar fascia; by its deep surface, with the
Flexor accessorius, the Lumbricales, the ten-
dons of the Flexor longus digitorum, and the
lateral plantar vessels and nerve, from which
it is separated by a thin layer of fascia. The
outer and inner borders are separated from the
adjacent muscles by means of vertical pro-
longations of the plantar fascia.
Fibrous Sheaths of the Flexor Tendons. —
These are not so well marked as in the fingers.
The flexor tendons of the toes as they run
along the phalanges are retained against the
bones by a fibrous sheath, forming osseo-
aponeurotic canals. These sheaths are formed
by strong fibrous bands which arch across the
tendons and are attached on each side to the
margins of the phalanges. Opposite the mid-
dle of the proximal and second phalanges the
sheath is very strong, and the fibres pass
transversely, but opposite the joints it is
much thinner, and the fibres pass obliquely.
Each sheath is lined by a synovial mem-
brane which is reflected on the contained
tendon.
The Abductor Minimi Digiti (m. abductor
digiti quinti] lies along the outer border of the
foot. It arises, by a very broad origin, from
the outer tubercle of the os calcis, from the
under surface of the os calcis between the two
tubercles, from the forepart of the inner
tubercle, from the plantar fascia and the in-
termuscular septum, between it and the Flexor
brevis digitorum. Its tendon, after gliding
over a smooth facet on the under surface of
the base of the fifth metatarsal bone, is inserted
with the short Flexor of the little toe into the outer side of the base of the first
phalanx of this toe.
Relations. — By its superficial surface, with the plantar fascia; by its deep sur-
face, with the Flexor accessorius, the Flexor brevis minimi digiti, the long plantar
ligament, and the tendon of the Peroneus longus. On its inner side are the
lateral plantar vessels and nerve, and it is separated from the Flexor brevis
digitorum by a vertical septum of fascia.
Dissection. — The muscles of the superficial layer should be divided at their origin by insert-
ing the knife beneath each, and cutting obliquely backward, so as to detach them from the
bone; they should then be drawn forward, in order to expose the second layer, but not cut away
at their insertion. The two layers are separated by a thin membrane, the deep plantar fascia,
FIG. 3,54. — Muscles of the sole of the foot.
First layer.
THE PLANTAR REGION 549
on the removal of which is seen the tendon of the Flexor longus digitorum, the Flexor accessorius,
the tendon of the Flexor longus hallucis, and the Lumbricales. The long flexor tendons
diverge from each other at an acute angle; the Flexor longus hallucis runs along the inner side
of the foot, on a plane superior to that of the Flexor longus digitorum, the direction of which is
obliquely outward.
The Second Layer.
Flexor accessorius. Lumbricales.
The Flexor Accessorius (m. quadratus plantae] arises by two heads, which are
separated from each other by the long plantar ligament: the inner or larger head,
which is muscular, being attached to the inner concave surface of the os calcis
below the groove which lodges the tendon of the Flexor longus digitorum; the
outer head, flat and tendinous, to the outer surface of the os calcis, in front of its
lesser tubercle, and to the long plantar ligament; the two portions join at an
acute angle, and are inserted into the outer margin and upper and under sur-
faces of the tendon of the Flexor longus digitorum, forming a kind of groove in
which the tendon is lodged.1
Relations. — By its superficial surface, with the muscles of the superficial layer,
from which it is separated by the lateral plantar vessels and nerves; by its deep
surface, with the os calcis and long calcaneo-cuboid ligament.
The Lumbricales are four small muscles accessory to the tendons of the Flexor
longus digitorum: they arise from the tendons of the long Flexor, as far back as
their angle of division, each arising from two tendons, except the internal one.
Each muscle terminates in a tendon, which passes forward on the inner side of
the four lesser toes and is inserted into the expansion of the long Extensor tendon
on the dorsum of the first phalanx of the corresponding toe.
Dissection. — The flexor tendons should be divided at the back part of the foot, and the
Flexor accessorius at its origin, and drawn forward, in order to expose the third layer.
The Third Layer.
Flexor brevis hallucis. Flexor brevis minimi digiti.
Adductor obliquus hallucis. Adductor transversus hallucis.
The Flexor Brevis Hallucis (m. flexor hallucis brevis) arises, by a pointed
tendinous process, from the inner part of the under surface of the cuboid bone,
from the contiguous portion of the external cuneiform, and from the prolongation
of the tendon of the Tibialis posticus, which is attached to that bone. The
muscle divides, in front, into two portions, which are inserted into the inner
and outer sides of the base of the first phalanx of the great toe, a sesamoid bone
being developed in each tendon at its insertion. The inner portion of this
muscle is blended with the Abductor hallucis previous to its insertion, the outer
portion with the Adductor obliquus hallucis, and the tendon of the Flexor
longus hallucis lies in a groove between them.
Relations. — By its superficial surface, with the Abductor hallucis and the ten-
don of the Flexor longus hallucis; by its deep surface, with the tendon of the
Peroneus longus and metatarsal bone of the great toe; by its inner border, with
the Abductor hallucis; by its outer border, with the Adductor obliquus hallucis.
The Adductor Obliquus Hallucis is a large, thick, fleshy mass passing obliquely
across the foot and occupying the hollow space between the four inner meta-
tarsal bones. It arises from the tarsal extremities of the second, third, and fourth
metatarsal bones, and from the sheath of the tendon of the Peroneus longus,
1 According to Turner, the fibres of the Flexor accessorius end in aponeurotic bands, which contribute slips
to the second, third, and fourth digits.
550
THE MUSCLES AND FASCIAE
and is inserted, together with the outer portion of the Flexor brevis hallucis, into
the outer side of the base of the first phalanx of the great toe.
The small muscles of the great toe, the Abductor, Flexor brevis, Adductor
obliquus, and Adductor transversus, like the similar muscles of the thumb, give
aff fibrous expansions, at their insertions, to blend with the long Extensor tendon.
FIG. 355. — Muscles of the sole of the foot.
Second layer.
FIG. 356. — Muscles of the sole of the foot.
Third layer.
The Flexor Brevis Minimi Digiti (TO. flexor digiti quinti brevis) lies on the meta-
tarsal bone of the little toe, and much resembles one of the Interossei. It arises
from the base of the metatarsal bone of the little toe, and from the sheath of the
Peroneus longus; its tendon is inserted into the base of the first phalanx of
the little toe on its outer side. Occasionally some of the deeper fibres of the
muscle are inserted into the outer part of the distal half of the fifth metatarsal
bone; these are described by some as a distinct muscle, the Opponens minimi
digiti.
Relations. — By its superficial surface, with the plantar fascia and tendon of
the Abductor minimi digiti; by its deep surface, with the fifth metatarsal bone.
THE PLANTAR REGION
551
The Adductor Transversus Hallucis (TO. transversus pedis) is a narrow, flat, *
muscular fasciculus, stretched transversely across the heads of the metatarsal bones,
between them and the flexor tendons. It arises from the inferior rnetatarso-
phalangeal ligaments of the three outer toes, sometimes only from the third and
fourth and from the transverse ligament of the metatarsus; and is inserted into
the outer side of the first phalanx of the great toe, its fibres being blended with
the tendon of insertion of the Adductor obliquus hallucis.
Relations. — By its superficial surface, with the tendons of the long and short
Flexors and Lumbricales ; by its deep surface, with the Interossei.
The Fourth Layer.
The Interossei.
The Interossei Muscles in the foot are similar to those in the hand, with this
exception, that they are grouped around the middle line of the*second toe, instead
of the middle line of the third finger, as in the hand. They are seven in number,
and consist of two groups, Dorsal and Plantar.
FIG. 357. — The Dorsal interossei. Left foot.
FIG. 358.— The Plantar interossei. Left foot.
The Dorsal Interossei (TO. interossei dorsales) ,four in number, are situated between
the metatarsal bones. They are bipenniform muscles, arising by two heads from
the adjacent sides of the metatarsal bones, between which they are placed; their
tendons are inserted into the bases of the first phalanges, and into the aponeurosis
of the common extensor tendon. In the angular interval left between the heads
of each muscle at its posterior extremity the perforating arteries pass to the
dorsum of the foot, except in the First interosseous muscle, where the interval
allows the passage of the communicating branch of the dorsalis pedis artery. The
First dorsal interosseous muscle is inserted into the inner side of the second toe;
the other three are inserted into the outer sides of the second, third, and fourth toes.
The Plantar Interossei (TO. interossei plantares], three in number, lie beneath,
rather than between, the metatarsal bones. They are single muscles, and are
each connected with but one metatarsal bone. They arise from the base and
552 THE MUSCLES AND FASCIA
inner sides of the shaft of the third, fourth, and fifth metatarsal bones, and are
inserted into the inner sides of the bases of the first phalanges of the same toes,
and into the aponeurosis of the common extensor tendon.
Nerves. — The Flexor brevis digitorum, the Flexor brevis and Abductor hallucis,
and the innermost Lumbrical1 are supplied by the medial plantar nerve. All
the other muscles in the sole of the foot by the lateral plantar. The first dorsal
interosseous muscle frequently receives an extra filament from the internal
branch of the anterior tibial nerve on the dorsum of the foot, and the second
dorsal interosseous a twig from the external branch of the same nerve.
Actions. — All the muscles of the foot act upon the toes, and for purposes of
description as regard their action may be grouped as Abductors, Adductors,
Flexors, or Extensors. The Abductors are the Dorsal interossei, the Abductor
hallucis, and the Abductor minimi digiti. The Dorsal interossei are abductors
from an imaginary line passing through the axis of the second toe, so that the
first muscle draws the second toe inward, toward the great toe; the second muscle
draws the same toe outward; the third draws the third toe, and the fourth draws
the fourth toe, in the same direction. Like the interossei in the hand, they also
flex the proximal phalanges and extend the two terminal phalanges. The Abduc-
tor hallucis abducts the great toe from the others, and also flexes the proximal
phalanx of this toe. And in the same way the action of the Abductor minimi
digiti is twofold — as an abductor of this toe from the others, and also as a flexor
of the proximal phalanx. The Adductors are the Plantar interossei, the Adductor
obliquus hallucis, and the Adductor transversus hallucis. The Plantar inter-
osseous muscles adduct the third, fourth, and fifth toes toward the imaginary
line passing through the second toe, and by means of their insertion into the
aponeurosis of the extensor tendon they, with the dorsal interossei, flex the prox-
imal phalanges and extend the two terminal phalanges. The Adductor obliquus
hallucis is chiefly concerned in adducting the great toe toward the second one,
but also assists in flexing this toe. The Adductor transversus hallucis approxi-
mates all the toes, and thus increases the curve of the transverse arch of the
metatarsus. The Flexors are the Flexor brevis digitorum, the Flexor accessorius,
the Flexor brevis hallucis, the Flexor brevis minimi digiti, and the Lumbricales.
The Flexor brevis digitorum flexes the second phalanges upon the first, and, con-
tinuing its action, may flex the first phalanges also and bring the toes together.
The Flexor accessorius assists the Long flexor of the toes, and converts the
oblique pull of the tendons of that muscle into a direct backward pull upon the
toes. The Flexor brevis hallucis flexes and slightly adducts the first phalanx of
the great toe. The Flexor brevis minimi digiti flexes the little toe and draws its
metatarsal bone downward and inward. The Lumbricales, like the correspond-
ing muscles in the hand, assist in flexing the proximal phalanx, and by their
insertion into the long Extensor tendon aid in straightening the two terminal
phalanges. The only muscle in the Extensor group is the Extensor brevis digi-
torum. It extends the first phalanx of the great toe, and assists the long Exten-
sor in extending the next three toes, and at the same time gives to the toes an
outward direction when they are extended.
SURFACE FORM OF THE LOWER EXTREMITY.
Of the muscles of the thigh, those of the iliac region have no influence on surface form,
while those of the anterior femoral region, being to a great extent superficial, largely con-
tribute to the surface form of this part of the body. The Tensor fasciae femoris pro-
1 Formerly the two inner Lumbricales were described as being supplied by the internal plantar nerve. Brooks
(Journal of Anatomy, vol. xxi. p. 575) in ten dissections found that in nine of them only the inner Lumbrical
obtained its nerve supply from this source. In the tenth instance the first and second Lumbricales were
supplied by both external and internal plantar.
SURFACE FORM OF THE LOWER EXTREMITY 553
duces a broad elevation immediately below the anterior portion of the crest of the ilium and
behind the anterior superior spinous process. From its lower border a longitudinal groove,
corresponding to the ilio-tibial band, may be seen running down the outer side of the thigh to
the outer side of the knee-joint. The Sartorius muscle, when it is brought into action by flexing
the leg on the thigh and the thigh on the pelvis, and rotating the thigh outward, presents a
well-marked surface form. At its upper part, where it constitutes the outer boundary of
Scarpa's triangle, it forms a prominent oblique ridge, which becomes changed into a flattened
plane below, and this gradually merges in a general fulness on the inner side of the knee-joint.
When the Sartorius is not in action, a depression exists between the Quadriceps extensor and the
Adductor muscles, running obliquely downward and inward from the apex of Scarpa's triangle
to the inner side of the knee, which depression corresponds to this muscle. In the depressed angle
formed by the divergence of the Sartorius and Tensor fasciae femoris muscles, just below the
anterior superior spinous process of the ilium, the Rectus femoris muscle appears, and, below
this, determines to a great extent the convex form of the front of the thigh. In a well-developed
subject the borders of the muscle, when in action, are clearly to be defined. The VastUS externus
forms a long flattened plane on the outer side of the thigh, traversed by the longitudinal groove
formed by the ilio-tibial band. The VastUS internus, on the inner side of the lower half of the
thigh, gives rise to a considerable prominence, which increases toward the knee and terminates
somewhat abruptly in this situation with a full, curved outline. The Crureus and Subcrureus
are completely hidden, and do not directly influence surface form. The Adductor muscles,
constituting the internal femoral group, are not to be individually distinguished from each
other, with the exception of the upper tendon of the Adductor longus and the lower tendon of
the Adductor magnus. The upper tendon of the Adductor longUS, when the muscle is in action,
stands out as a prominent ridge, which runs obliquely downward and outward from the neigh-
borhood of the pubic spine, and forms the inner boundary of a flattened triangular space on
the upper part of the front of the thigh, known as Scarpa's triangle. The lower tendon of the
Adductor magnus can be distinctly felt as a short ridge extending down to the Adductor tubercle
on the internal condyle, between the Sartorius and Vastus internus. The Adductor group
of muscles fills in the triangular space at the upper part of the thigh, formed between the oblique
femur and the pelvic wall, and to them is due the contour of the inner border of the thigh, the
Gracilis largely contributing to the smoothness of the outline. These muscles are not marked
off on the surface from those of the posterior femoral region by any intermuscular marking; but
on the outer side of the thigh these latter muscles are defined from the Vastus externus by a
distinct marking, corresponding to the external intermuscular septum. The Gluteus maximus
and a part of the Gluteus medius are the only muscles of the buttock which influence surface
form. The other part of the Gluteus medius, the Gluteus minimus, and the External rotators
are completely hidden. The Gluteus maximus forms the full rounded outline of the buttock;
it is more prominent behind, compressed in front, and terminates at its tendinous insertion in
a depression immediately behind the great trochanter. Its lower border does not correspond
to the gluteal fold, but is much more oblique, being marked by a line drawn from the side of
the coccyx to the junction of the upper with the lower two-thirds of the thigh on the outer side.
From beneath the lower margin of this muscle the Hamstring muscles appear, at first narrow
and not well marked, but as they descend becoming more prominent and widened out, and
eventually dividing into two well-marked ridges, which constitute the upper boundaries of the
popliteal space, and are formed by the tendons of the inner and outer hamstring muscles respect-
ively. In the upper part of the thigh these muscles are not to be individually distinguished
from each other, but lower down the separation between the Semitendinosus and Semimem-
branosusjs denoted by a slight intermuscular marking. The external hamstring tendon formed
by the Biceps is seen as a thick cord running down to the head of the fibula. The inner ham-
string tendons comprise the Semitendinosus, the Semimembranosus, and the Gracilis. The
Semitendinosus is the most internal of these, and can be felt, in certain positions of the limb,
as a sharp cord; the Semimembranosus is thick, and the Gracilis is situated a little farther
forward than the other two. All the muscles on the front of the leg appear to a certain extent
somewhere on the surface, but the form of this region is mainly dependent upon the Tibialis
anticus and the Extensor longus digitorum. The Tibialis anticus is well marked, and presents
a fusiform enlargement at the outer side of the tibia, and projects beyond the crest of the shin-
bone. From the muscular mass its tendons may be traced downward, standing out boldly,
when the muscle is in action, on the front of the tibia and ankle-joint, and coursing down to its
insertion along the inner border of the foot. A well-marked groove separates this muscle exter-
nally from the Extensor longus digitorum, which fills up the rest of the space between the upper
part of the shaft of the tibia and fibula. It does not present so bold an outline as the Tibialis
anticus, and its tendon below, diverging from the tendon of the Tibialis anticus, forms with the
latter a sort of plane, in which may be seen the tendon of the Extensor proprius hallucis. A
groove on the outer side of the extensor longus digitorum, seen most plainly when the muscle
is in action, separates the tendon from a slight eminence corresponding to the Peroneus tertius.
The fleshy fibres of the Peroneus longus are strongly marked at the upper part of the outer
554 THE MUSCLES AND FASCIA
side of the leg, especially when the muscle is in action. It forms a bold swelling, separated by
furrows from the Extensor longus digitorum in front and the Soleus behind. Below, the fleshy
fibres terminate abruptly in a tendon which overlaps the more flattened form of the Peroneus
brevis. At the external malleolus the tendon of the Peroneus brevis is more marked than that
of the Peroneus longus. On the dorsum of the foot the tendons of the Extensor muscles,
emerging from beneath the anterior annular ligament, spread out and can be distinguished
in the following order: The most internal and largest is the Tibialis anticus.-then the Extensor
proprillS hallucis J next comes the Extensor longUS digitorum, dividing into four tendons to
the four outer toes; and lastly, most externally, is the Peroneus tertius. The flattened form of
the dorsum of the foot is relieved by the rounded outline of the fleshy belly of the Extensor
brevis digitorum, which forms a soft fulness on the outer side of the tarsus in front of the external
malleolus, and by the Dorsal interossei, which bulge between the metatarsal bones. At the
back of the knee is the popliteal space, bounded above by the tendons of the hamstring muscle;
below, by the two heads of the Gastrocnemius. Below this space is the prominent fleshy mass
of the calf of the leg, produced by the Gastrocnemius and Soleus. When these muscles are
in action, as in standing on tiptoe, the borders of the Gastrocnemius are well defined, presenting
two curved lines, which converge to the tendon of insertion. Of these borders, the inner is
more prominent than the outer. The fleshy mass of the calf terminates somewhat abruptly
below in the tendo Achillis, which stands out prominently on the lower part of the back of the
leg. It presents a somewhat tapering form in the upper three-fourths of its extent, but widens
out slightly below. When the muscles of the calf are in action, the lateral portions of the Soleus
may be seen, forming curved eminences, of which the outer is the longer, on either side of the
Gastrocnemius. Behind the inner border of the lower part of the shaft of the tibia a well-
marked ridge, produced by the tendon of the Tibialis posticus, is visible when this muscle is in
a state of contraction. On the sole of the foot the superficial layer of muscles influences surface
form; the Abductor minimi digiti most markedly. This muscle forms a narrow rounded
elevation along the outer border of the foot, while the Abductor hallucis does the same, though
to a less extent, on the inner side. The Flexor brevis digitorum, bound down by the pldntar
fascia, is not very apparent; it produces a flattened form, covered by the thickened skin of the
sole, which is here thrown into numerous wrinkles.
SURGICAL ANATOMY OF THE LOWER EXTREMITY.
The student should now consider the effects produced by the action of the various muscles
in fractures of the bones of the lower extremity. The more common forms of fractures are
selected for illustration and description.
PYRIFORMIS.
GEMELLUS SUPERIOR.
OBTURATOR INTERNUS
GEMELLUS INFERIOR.
OBTURATOR EXTERNUS.
QUADRATUS FEMORIS.
FIG. 359.- -Fracture of the neck of the femur within the capsular ligament.
In fracture of the neck of the femur internal to the capsular ligament (Fig. 359) the charac-
teristic marks are slight shortening of the limb and eversion of the foot, neither of which symp-
SURGICAL ANATOMY OF THE LOWER EXTREMITY 555
toms occurs, however, in some cases until some time after the injury. The eversion is caused
l.v the weight of the limb rotating it outward. The shortening is produced by the action of the
Glutei, and by the Rectus femoris in front and the Biceps, Semitendinosus, and Semimem-
branosus behind. The treatment is extension by means of adhesive plaster and weights and
counter-extension by raising the foot of the bed, eversion being corrected by sand-bags. In
some cases Thomas's splint is used.
In fracture of the femur just below the trochanters (Fig. 360) the upper fragment, the por-
tion chiefly displaced, is tilted forward almost at right angles with the pelvis by the combined
action of the Psoas and Iliacus, and, at the same time, everted
and drawn outward by the External rotator and Glutei muscles,
causing a marked prominence at the upper and outer side of the
thigh, and much pain from the bruising and laceration of the
muscles. The limb is shortened, in consequence of the lower
fragment being drawn upward by the rectus in front, and the
Biceps, Semimembranosus, and Semitendinosus behind, and is
at the same time everted. This fracture may be reduced by
direct relaxation of all the opposing muscles, to effect which the
limb should be put up in such a manner that the thigh is flexed
on the pelvis and the leg on the thigh, the extremity being placed
SEMI-
MEMBRANOSUS.
SEMI-
TENDINOSUS.
FIG. 360. — Fracture of the femur
below the trochanters.
FIG. 361. — Fracture of the femur
above the condyles.
FIG. 362. — Fracture of
the patella.
upon a double inclined plane and extension being made in the axis of the partly flexed
thigh by means of adhesive plaster and weights. In some cases it is necessary to incise and
wire the fragments together.
Oblique fracture of the femur immediately above the condyles (Fig. 361) is a formidable
injury, and attended with considerable displacement. On examination of the limb the lower
fragment may be felt deep in the popliteal space, being drawn backward by the Gastrocnemius
and Plantaris muscles, and upward by the Hamstring and Rectus muscles. The pointed end
of the upper fragment is drawn inward by the Pectineus and Adductor muscles, and tilted for-
ward by the Psoas and Iliacus, piercing the Rectus muscle and occasionally the integument.
Relaxation of these muscles and direct approximation of the broken fragments are effected by
placing the limb on a double inclined plane. The greatest care is requisite in keeping the
pointed extremity of the upper fragment in proper position; otherwise, after union of the
fracture, the power of extension of the limb is partially destroyed from the Rectus muscle being
held down by the fractured end of the bone, and from the patella, when elevated, being drawn
upward against the projecting fragment.
In fracture of the patella (Fig. 362) the fragments are separated by the effusion which takes
place into the joint, and by the action of the Quadriceps extensor; the extent of separation of
the two fragments depending upon the degree of laceration of the ligamentous structures
around the bone. Some cases may be treated by a posterior straight splint, the fragments
being pulled together by strips of adhesive plaster. In many cases it is advisable to incise,
remove intervening pieces of fibrous tissue and wire the fragments together.
556
THE MUSCLES AND FASCIAE
The tibia is fractured most commonly by indirect force at the junction of the middle third
with the lower third of the shaft. Compound fractures are more common in the leg than
in any other region of the body because the tibia is such a superficial bone and is so much
exposed to injury. Most fractures from indirect force are oblique.
In oblique fracture of the shaft of the tibia (Fig. 363), if the fracture has taken place obliquely
from above, downward and forward, the fragments ride over one another, the lower fragments
being drawn backward and upward by the powerful action of the muscles of the calf; the
pointed extremity of the upper fragment projects forward immediately beneath the integu-
ment, often protruding through it and rendering the fracture a compound one. If the direc-
tion of the fracture is the reverse of that shown in the figure, the pointed extremity of the lower
fragment projects forward, riding upon the lower end of the upper one. By bending the knee,
FIG. 363. — Oblique fracture of
the shaft of the tibia.
FIG. 364. — Fracture of the fibula with dislocation of
the foot outward — " Pott's fracture."
which relaxes the opposing muscles, and making extension from the ankle and counter-
extension at the knee, the fragments may be brought into apposition. It is often necessary,
however, in a compound fracture, to remove a portion of the projecting bone with the saw
before complete adaptation can be effected.
Fracture of the fibula with dislocation of the foot outward (Fig. 364), commonly known as
Pott's fracture, is one of the most frequent injuries of the ankle-joint. The fibula is frac-
tured about three inches above the ankle; in addition to this the internal malleolus is broken
off, or the deltoid ligament torn through, and the end of the tibia displaced from the correspond-
ing surface of the astragalus. The foot is markedly everted, and the sharp edge of the upper
end of the fractured malleolus presses strongly against the skin ; at the same time, the heel is
drawn up by the muscles of the calf. This injury can generally be reduced by flexing the leg at
right angles with the thigh, which relaxes all the opposing muscles, and by making extension
from the ankle and counter-extension at the knee.
THE BLOOD-VASCULAR SYSTEM.
A NGIOLOGY is the branch of anatomy which treats of the blood-vessels.
_L\_ The blood-vascular system comprises the heart and blood-vessels with
their contained fluid, the blood.
The Heart is the central organ of the entire system, and is a hollow muscle;
by its contraction the blood is pumped to all parts of the body through a com-
plicated series of tubes, termed arteries. The arteries undergo almost infinite
ramification in their course throughout the body, and end in very minute vessels,
called arterioles, which in their turn open into a close-meshed network of micro-
scopic vessels, termed capillaries. After the blood has passed through the capil-
laries it enters into minute vessels called venules and from them it is collected
into a series of larger vessels, called veins, by which it is returned to the heart.
The passage of the blood through the heart and blood-vessels constitutes what is
termed the circulation of the blood, of which the following is an outline.
The human heart is divided by a septum into two halves, right and left, each
half being further constricted into two cavities, the upper of the two being termed
the auricle and the lower the ventricle. The heart therefore consists of four
chambers or cavities, two forming the right half, the right auricle and right
ventricle; and two the left half, the left auricle and left ventricle. The right
half of the heart contains venous or impure blood ; the left, arterial or pure blood.
From the cavity of the left ventricle the pure blood is carried into a large artery,
the aorta, through the numerous branches of which it is distributed to all parts
of the body, with the exception of the lungs. In its passage through the capil-
laries of the body the blood gives up to the tissues the materials necessary for
their growth and nourishment, and at the same time receives from the tissues the
waste products resulting from their metabolism, and in doing so becomes changed
from arterial or pure blood into venous or impure blood, which is collected by the
veins and through them returned to the right auricle of the heart. From this
cavity the impure blood passes into the right ventricle, from which it is conveyed
through the pulmonary arteries to the lungs. In the capillaries of the lungs it
again becomes arterialized, and is then carried to the left auricle by the pulmonary
veins. From this cavity it passes into that of the left ventricle, from which the
cycle once more begins.
The course of the blood from the left ventricle through the body generally to
the right side of the heart constitutes the greater or systemic circulation, while its
passage from the right ventricle through the lungs to the left side of the heart is
termed the lesser or pulmonary circulation.
It is necessary, however, to state that the blood which circulates through the
spleen, pancreas, stomach, small intestine, and the greater part of the large intes-
tine is not returned directly from these organs to the heart, but is collected into
a large vein, termed the portal vein, by which it is carried to the liver. In the
liver this vein divides, after the manner of an artery, and ultimately ends in
capillary vessels, from which the rootlets of a series of veins, called the hepatic
veins, arise; these carry the blood into the postcava (inferior vena cava), which
conveys it to the right auricle.
(557)
558
THE BLOOD -VASCULAR SYSTEM
Pulmonary Capillaries
From this it will be seen that the blood contained in the portal vein passes
through two sets of capillary vessels: (1) those in the spleen, pancreas, stomach,
etc., and (2) those in the liver.
Speaking generally, the arteries may be said to contain pure, and the veins
impure, blood. This is true of the systemic, but not of the pulmonary, vessels,
since it has been seen that the impure blood is conveyed from the heart to the
lungs by the pulmonary arteries, and the pure blood returned from the lungs to
the heart by the pulmonary veins. Arteries,
therefore, must be defined as vessels which
convey blood from the heart, and veins as
vessels which return blood to the heart.
The heart and lungs are contained within
the cavity of the thorax, the walls of which
afford them protection (Fig. 366). The heart
lies between the two lungs, and is there
enclosed within a sero-membranous bag, the
pericardium, while each lung is invested by a
serous membrane, the pleura. The skeleton
of the thorax was described on page 156.
The Cavity of the Thorax (cavum tho-
racis).— The capacity of the cavity of the
thorax does not correspond with its apparent
size externally, because (1) the space en-
closed by the lower ribs is occupied by some
of the abdominal viscera; and (2) the cavity
extends above the first rib into the neck.
The size of the cavity of the thorax is con-
stantly varying during life, with the move-
ments of the ribs and diaphragm, and with
the degree of distention of the abdominal
viscera. From the collapsed state of the
lungs, as seen when the thorax is opened,
in the dead body, it would appear as if the
viscera only partly filled the cavity of the
thorax, but during life there is no vacant
space, that which is seen after death being
filled up during life by the expanded lungs.
The Upper Opening of the Thorax
(apertura thoracis superior) . — The parts
which pass through the upper opening of
the thorax are, from before backward in or
near the middle line, the Sterno-hyoid and
Sterno-thyroid muscles, the remains of the
thymus gland, the trachea, oesophagus, thoracic duct, the inferior thyroid veins,
and the Longus colli muscle of each side; at the sides, the innominate artery,
the left common carotid, and left subclavian arteries, the internal mammary
and superior intercostal arteries, the right and left innominate veins, the vagus,
cardiac, phrenic, and sympathetic nerves, the anterior branch of the first thoracic
nerve, and the recurrent laryngeal nerve of the left side. The apex of each lung,
covered by the pleura, also projects through this aperture, a little above the margin
of the first rib.
The Lower Opening of the Thorax (apertura thoracis inferior) is wider trans-
versely than from before backward. It slopes obliquely downward and back-
ward, so that the cavity of the thorax is much deeper behind than in front. The
FIG. 365. — Diagram to show the course of the
circulation of the blood.
THE PERICARDIUM
559
Diaphragm (see page 429) closes in the opening, forming the floor of the thorax.
The floor is flatter at the centre than at the sides, and is higher on the right side
than on the left, corresponding in the dead body to the upper border of the fifth
i'
G. 366. — Front view of the thorax. The ribs and sternum are represented in relation to the lungs, heart,
other internal organs. 1. Pulmonary orifice. 2. Aortic orifice. 3. Left auriculo- ventricular orifice. 4.
it aiirinnlo-ventriciilar orifine.
FIG
Right auriculo-ventricular orifice.
costal cartilage on the former, and to the corresponding part of the sixth costal
cartilage on the latter. From the highest point on each side the floor slopes sud-
denly downward to the attachment of the Diaphragm to the ribs; this is more
marked behind than in front, so that only a narrow space is left between it and
the wall of the thorax.
THE PERICARDIUM.
The pericardium (Figs. 367, 368, 369, 370, 371, and 372) is a conical sero-
membranous sac, placed in the middle mediastinum. In this sac the heart and
the commencement of the great vessels are contained. It is placed behind the
sternum and the cartilages of the third, fourth, fifth, sixth, and seventh ribs of
the left side, in the interval between the pleurae.
Its apex is directed upward, and surrounds the great vessels about two inches
above their origin from the base of the heart. Its base is attached to the central
tendon and to the left part of the adjoining muscular structure of the Diaphragm.
In front it is separated from the sternum by the remains of the thymus gland
560
THE BLOOD -VASCULAR SYSTEM
above and a little loose areolar tissue below, and is covered by the margins of the
lungs, especially the left. Behind, it rests upon the bronchi, the oesophagus, and
the descending aorta. Laterally, it is covered by the pleurae, and is in relation to
the inner surface of the lungs; the phrenic nerve with its accompanying vessels
descends between the pericardium and pleura on either side (Fig. 371).
Structure of the Pericardium. — The pericardium is a fibre-serous membrane,
and consists, therefore, of two layers, an external fibrous and an internal serous.
Right common-
carotid artery.
Inferior thyroid ^
vein.
Left innomi-^
nate vein.
Right innomi-^
nate vein.
Precava or
Superior vena
cava.
Bight pulmo-
nary veins.
Right sub-
'clavian art.
Left common
carotid art.
Left sub-
clavian
rtery.
FIG. 367. — Pericardium from in front. The sac has been distended with plaster. (From a preparation
in the Museum of the Royal College of Surgeons of England.)
The Fibrous Layer is a strong, dense, connective-tissue membrane. Above, it
surrounds the great vessels arising from the base of the heart, on which it is
continued in the form of tubular prolongations which are gradually lost upon
their external coat, the strongest being that which encloses the aorta. The peri-
cardium may be traced over these vessels, to become continuous with the deep
layer of the cervical fascia. The prolongations to the cervical fascia constitute the
vertebro-pericardial ligaments (Fig. 370). In front the pericardium is connected to
the posterior surface of the sternum by two fibrous bands, the superior and inferior
sterno-pericardiac ligaments or ligaments of Luschka (ligamenta sternopericardiaca)
(Fig. 370). The superior sterno-pericardial ligament, called also the sternocosto-
THE PERICARDIUM
561
pericardial ligament (Fig. 370), passes to the manubrium. The inferior sterno-
pericardial ligament, called also the xipho-pericardial ligament (Fig. 370), passes to
the ensiform cartilage. On each side of the ascending aorta the pericardium sends
upward a diverticulum : the one on the left side, somewhat conical in shape, passes
upward and outward, between the arch of the aorta and the pulmonary artery,
as far as the ductus arteriosus, where it terminates in a csecal extremity, which is
attached by loose connective tissue to the obliterated duct (Fig. 367). The one on
the right side passes upward and to the right, between the ascending aorta and
Left subclavian artery.
Right pulmonary artery
Riqht subclavian artery.
Left com/Him
ca rot i<l artery.
Eight common
carotid artery.
Right pulmonary
veins.
FIG. 368. — Pericardium from behind. (From the same preparation as the preceding figure.)
precava (vena cava superior) , and also terminates in a csecal extremity. Below,
the fibrous layer is attached to the central tendon of the Diaphragm, and on the left
side to its muscular fibres. The pericardium is fixed to the Diaphragm by the
anterior phreno-pericardial ligament and by the lateral phreno-pericardial ligaments
(Fig. 370).
The vessels receiving fibrous prolongations from this membrane are the aorta,
the precava, the right and left pulmonary arteries, and the four pulmonary veins.
The postcava (inferior vena cava) enters the pericardium through the central
tendon of the Diaphragm, and consequently it receives no covering from the
fibrous layer (Fig. 371).
36
562
THE BLOOD -VASCULAR SYSTEM
The Serous Pericardium invests the heart, and is then reflected on the inner sur-
face of the fibrous pericardium. It consists, therefore, of a visceral layer (epicar-
dium) and a parietal layer. The former invests the surface of the heart, and the
commencement of the great vessels, to the extent of an inch and a half from
their origin ; from these it is reflected upon the inner surface of the fibrous layer.
The serous membrane encloses the aorta and pulmonary artery in a single tube,
so that a passage, termed the great transverse sinus of the pericardium (sinus trans-
versus pericardii) , exists between these vessels in front and the auricle behind.
This sinus is closed above and below but often to the right and left. The mem-
RIGHT
PULMONARY.
VEIN
PAR I ETA
PERICARDIUM
FIG. 369. — The line of reflection of the serous pericardium. (Modified from Poirier and Charpy.)
brane only partially covers the precava (superior vena cava) and the four pulmo-
nary veins, and scarcely covers the postcava (inferior vena cava), as this vessel
enters the heart almost directly after it has passed through the Diaphragm. A deep
blind recess formed by the serous pericardium is found behind the heart when that
organ is raised up. This recess runs backward between the left auricle and the
posterior portion of the fibrous pericardium, and forms a diverticulum between the
heart and the oesophagus. This recess is called the oblique sinus. It passes upward
between the postcava and the lower left pulmonary vein and terminates between the
right and left pulmonary veins. The inner surface of the pericardium is covered
with endothelium, which rests upon a mixture of fibrous and elastic tissue, which is
smooth and glistening, and secretes a serous fluid (liquor pericardii), which serves
THE PERICARDIUM
563
to facilitate the movements of the heart. In the serous layer of the pericardium
arc many blood-vessels, lymph vessels, and nerves.
Arteries of the Pericardium. — These are derived from the internal mammary and
its musculo-phrenic branch, and from the descending thoracic aorta.
Nerves of the Pericardium. — These are branches from the vagus, the phrenic,
and the sympathetic.
The Vestigial Fold of the Pericardium. — Between the left pulmonary artery and
subjacent pulmonary vein and behind the left extremity of the transverse sinus is
a triangular fold of the serous pericardium; it is known as the vestigial fold of
VERTEBRO-
PERICAROIAL
LIGAMENTS
PRECAVA
OR
SUPERIOR
VENA CAVA
POSTCAVA
OR
INFERIOR
VENA CAVA
PHRENO-
PERICAROIAL
LIGAMENTS
SUPERIOR STERNO-
PERICARDIAL LIG-
AMENTS
ANTERIOR
SURFACE OF
PERICARDIUM
XIPHO-
PERICARDIAL
LIGAMENTS
FIG. 370. — Ligaments of the pericardium. (Modified from Teutleben.) Right lateral view, showing the right
vertebra — pericardial ligaments, the right phreno-pericardial, and the superior and* inferior sterno-pericardial
ligaments. (Poirier and Charpy.)
Marshall (ligamentum v. cavae sinistrae). It is formed by the duplicature of the
serous layer over the remnant of the lower part of the left precava (superior vena
cava, v. cava sinistra), or the duct of Cuvier, which, after birth, becomes obliterated,
and remains as a fibrous band stretching from the left superior intercostal vein
to the left auricle, where it is continuous with a small vein, the oblique vein of
Marshall (v. obliqua atrii sinistri [Marshalli]), which opens into the coronary sinus
and is a remnant of the fretal left precava.
Surgical Anatomy. — Aspiration of the pericardium (paracentesis of the pericardium) is occa-
sionally though seldom performed. It is only to be thought of when pericardial effusion endangers
life. The operation is very dangerous, because the effusion lifts the heart and pushes it forward.
564
THE BLOOD -VASCULAR SYSTEM
and the needle is apt to wound the heart or even enter one of the cavities. There is also danger
of wounding the internal mammary artery. The operation is never to be thought of in puru-
lent pericarditis. The safest way to aspirate is to introduce the needle in the fifth interspace
two inches to the left of the sternum and push it straight backward.
A better operation, even in a case of serous effusion, and one invariably selected in purulent
pericarditis, is incision (pericardotomy). A portion of the cartilage of the fifth rib. of the left
side is excised. The pericardium is exposed and is punctured, to learn the nature of the
contained fluid, and is then incised. By this method the surgeon avoids opening the pleural
cavity, and can obtain free drainage if pus is found.
Porter maintains that by "reason of the uncertain and varying relations of the pleura, and
also of the anterior position of the heart, whenever the pericardial sac is distended with fluid,
aspiration of the pericardium is a much more dangerous procedure than open incision when
done by skilled hands."
Line of reflection of
serous pericardium
Transverse sinus
of pericardium
Openings of
right pulmo-
nary veins
Openings of left
pulmonary veins
Left phrenic
nerve
FIG. 371. — Posterior wall of the pericardial sac, showing the lines of reflection of the serous
pericardium on the great vessels.
THE HEART (COE).
The heart is a* hollow muscular organ of a conical form, placed between the
lungs, and enclosed in the cavity of the pericardium.
Position (Fig. 372). — The heart is placed obliquely in the chest: the broad
attached end, or base (basis cordis), is directed upward, backward, and to the right,
and corresponds with the thoracic vertebrae, from the fifth to the eighth inclusive;
the apex (apex cordis) is directed downward, forward, and to the left, and corre-
sponds to the space between the cartilages of the fifth and sixth ribs, three-quarters
THE HEART
565
of an inch to the inner side, and an inch and a half below the left nipple, or about
three and a half inches from the middle line of the sternum. The heart is placed
behind the sternum, and projects farther into the left than into the right half of the
cavity of the chest, extending from the median line about three inches in the former
direction, and only one and a half in the latter; about one-third of the heart lies
to the right and two-thirds to the left of the mesial plane. The antero-superior
surface (fades stemocosialis) is round and convex, directed upward and forward,
is formed chiefly by the right auricle and ventricle, together with a small part of
the left ventricle. It lies behind the middle portion of the sternum and the costal
cartilages of the third, fourth, fifth, and sixth ribs on both sides. On account of
FIG. 372. — Position of the heart. The pericardium laid open. Adult male. (Poirier and Charpy.)
the heart's inclination to the left side, only a small part of it lies behind the carti-
lages of the right ribs. Lying in front of the heart, between it and the anterior
chest-wall, is the thin anterior margin of the lungs, covered by the pleura. On
the left side, however, owing to the notch in the anterior margin of the left
lung (incisura cardiaca) , there is a portion of the pericardium lying in contact
with the Triangularis sterni muscle. This area is called the area of greatest or
of absolute cardiac dulness or the area of superficial cardiac dulness. The postero-
inferior surface of the heart (fades diaphragmatica) , which looks downward rather
566
THE BLOOD -VASCULAR SYSTEM
than backward, is flattened and rests upon the Diaphragm, and is formed chiefly
by the left ventricle. The right or lower border is long, thin, and sharp; the left
or upper border short, but thick and round.
Size and Weight. — The heart, in the adult, measures five inches in length,
three inches and a half in breadth in the broadest part, and two inches and a half
in thickness. The prevalent weight, in the male, varies from ten to twelve ounces;
in the female, from eight to ten: its proportions to the body being as 1 to 169 in
males; 1 to 149 in females. The heart continues increasing in weight, and also
in length, breadth, and thickness, up to an advanced period of life: this increase
is more marked in men than in women.
AZVGOS
VEIN
H.EFT APPENDIX
AURICUUE
LEFT AURICULA
VENTRICULA
GROOVE
CORONARY
SINUS
OESOPHAGUS
FIG. 373. — Base of the heart in place. The attachments of the pericardium are outlined in red.
(Poirier and Charpy.)
Capacity of the Cavities of the Heart. — This matter is in dispute. Professor
'Cunningham believes that during life the capacity of the ventricles is nearly iden-
tical, each holding about four ounces of blood. Each auricle holds a little less
than four ounces. Stewart maintains that at each heart beat each ventricle
throws out only eighty-seven grams of blood. Morrant Baker1 says that, "taking
the mean of various estimates, it may be inferred that each ventricle is able to
contain four to six ounces of blood."
Fat upon the Heart. — Normally there is a certain amount of fat upon the
surface of the heart. This begins to appear in the early weeks of life and
increases in amount as age advances. It is found upon the surface of the
muscles and along the course of the vessels. Poirier is of the opinion that the
cardiac fat on the anterior surface of the heart is arranged in three movable
i Kirkes' Physiology, 10th ed., p. 156.
THE HEART 507
pads, which act as valves and fill vacant spaces about the heart created during
the- cardiac contractions.1
Component Parts. — The heart is subdivided by a muscular septum into two
lateral halves, which are named respectively the right or pulmonary heart and the
left or systemic heart; and a transverse constriction subdivides each half of the
organ into two cavities, the upper cavity on each side being called the auricle,
the lower the ventricle. The course of the blood through the heart cavities and
blood-vessels has already been described (page 557).
The division of the heart into four cavities is indicated by grooves upon its sur-
face. The groove separating the auricles from the ventricles is called the auriculo-
ventricular groove (sulcus coronarius). It is deficient, in front, where it is crossed
by the root of the pulmonary artery. It contains the trunks of the nutrient vessels
of the heart. The auricular portion occupies the base of the heart, and is sub-
divided into two cavities by a median septum. The two ventricles are also sepa-
rated into a right and left by two furrows, the interventricular grooves (sulci longi-
tudinales), which are situated one on the anterior (sulcus longitudinalis anterior),
the other on the posterior (sulcus longitudinalis posterior) surface; these extend
from the base of the ventricular portion to near the apex of the organ ; the former
being situated nearer to the left border of the heart, and the latter to the right.
It follows, therefore, that the right ventricle forms the greater portion of the
anterior surface of the heart, and the left ventricle more of its posterior surface.
The internal surface of the heart is lined with endocardium.
The auricular portion occupies the base of the heart and is subdivided into two
cavities, fore-chambers or auricles (atria), by a septum. As before stated, this portion
of the heart corresponds to the middle segment of the thoracic spine. Its form is
quadrilateral in shape, and has two processes extending upward from its two upper
angles, called the auricular appendices (appendices auriculae), between which are
found the aorta and the pulmonary artery. The greater part of the base of the
heart is formed by the left auricle. Its boundaries are, above, the pulmonary
artery; below, the coronary sinus; on the left it is bounded by the left superior
and inferior pulmonary veins, while on the right side it is limited by the sulcus
tenninalis. The latter corresponds to a ridge in the interior of the auricle, called
ttoe crista terminalis. Running vertically on this surface, just to the left of the
openings of the two venae cavae, is the interauricular furrow, which exactly indicates
the proportion of the base of the heart formed by each auricle.
Each of the cavities should now be separately examined.
The Right Fore-chamber or Auricle2 (atrium dextrum) is a little larger than the left,
its walls somewhat thinner, measuring about one line. It consists of two parts: a
principal cavity, the sinus venosus, situated posteriorly, and an anterior, smaller
portion, the auricular appendix. The right auricle is separated from the left auricle
by the interauricular septum (septum atriorum). Part of this septum is muscular;
part is composed of connective tissue.
The sinus venosus (sinus venarum) is the large quadrangular cavity, placed
between the two venae cavae; its walls are extremely thin; it is connected below
with the right ventricle, and internally with the left auricle, being free in the
rest of its extent. It is derived from a portion of the sinus reuniens of the
fcetal heart.
The right auricular appendix (auricula dextra) , so-called from its fancied resem-
blance to a dog's ear, is a small conical muscular pouch, the margins of which
present a dentated edge. It projects from the sinus forward and to the left
side, overlapping the root of the aorta.
1 L'appariel sero-graisseux. La Presse MSdicale, December 7, 1904.
2 In the new nomenclature the auricle is called the atrium, and auricular appendix is called the auricle.
568
THE BLOOD-VASCULAR SYSTEM
To examine the interior of the right auricle, an incision should be made along its right border,
from the entrance of the precava to that of the postcava. A second cut is to be made from the
centre of the first incision to the tip of the auricular appendix, and the flaps raised.
The internal surface of the right auricle is smooth, except in the appendix
and adjacent part of the anterior wall of the sinus venosus, where the muscular
wall is thrown into parallel ridges resembling the teeth of a comb and hence
named the musculi pectinati. These end behind on a vertical smooth ridge, the
Bristle passed through
Right Auricula- Ventricular opening.
FIG. 374.— The right auricle and ventricle laid open, the anterior walls of both being removed.
•
crista terminalis of His, the position of which is indicated on the surface of the
distended auricle by a furrow, the sulcus terminalis of His. The sulcus terminalis
passes from in front of the precava to the left of the postcava. It represents the
line of fusion of the sinus venosus of the embryo with the primitive auricle proper.
The right auricle presents the following parts for examination :
( Precava, or Superior vena cava.
Postcava, or Inferior vena cava.
Openings \ Coronary sinus. Valves
I Foramini Thebesii.
I Auriculo- ventricular.
Fossa ovalis.
Annulus ovalis.
Tuberculum Loweri.
Musculi pectinati.
The precava (superior vena cava) returns the blood from the upper half of the
body, and opens into the upper and back part of the auricle, the direction of its
orifice being downward and forward. The precava does not possess valves.
The postcava (inferior vena cava), larger than the precava, returns the blood from
the lower half of the body, and opens into the lowest part of the auricle near the
Eustachian.
Coronary.
THE HEART 569
septum, the direction of its orifice being upward and inward. The direction of
a current of blood through the precava would consequently be toward the auriculo-
ventricular orifice, whilst the direction of the blood through the postcava would be
toward the auricular septum. This is the normal direction of the two currents in
foetal life. The postcava does not possess valves until its termination at the right
auricle.
The coronary sinus (sinus coronarius] opens into the auricle, between the post-
cava and the auriculo-ventricular opening. It returns the blood from the substance
of the heart, and is protected by a semicircular fold of the lining membrane of
the auricle, the coronary valve or valve of Thebesius. The sinus, before entering
the auricle, is considerably dilated — nearly to the size of the end of the little
finger. Its wall is partly muscular, and at its junction with the great coronary
vein it is somewhat constricted and is furnished with a valve consisting of two
unequal segments.
The foramini Thebesii (foramina venarum minimarum) are numerous minute
fossa3 or apertures on various parts of the inner surface of the auricle. Many of
these foramina have at their points the minute openings of small veins (venae
minimfle cordis). They return the blood directly from the muscular substance
of the heart. Some of these foramina are minute depressions in the walls of the
heart, presenting a closed extremity.
The right auriculo-ventricular opening or the tricuspid orifice (ostium venosum
dextrum) is the large oval aperture of communication between the right auricle
and the ventricle, to be presently described.
The Eustachian valve (valvula venae cavae inferioris [Eustachii]) is situated
between the anterior margin of the postcava and the auriculo-ventricular orifice.
It is semilunar in form, its convex margin being attached to the wall of the vein;
its concave margin, which is free, terminating in two cornua, of which the left is
attached to the anterior edge of the annulus ovalis, the right being lost on the wall
of the auricle. The valve is formed by a duplicature of the lining membrane of
the auricle and contains a few muscular fibres.
In the foetus this valve is of large size, and serves to direct the blood from the
postcava, through the foramen ovale, into the left auricle.
In the adult it is occasionally large, and may assist in preventing the reflux
of blood into the postcava; more commonly it is small, and its free margin presents
a cribriform or filamentous appearance; occasionally it is altogether wanting.
The coronary valve or valve of Thebesius (valvulae sinus coronarii [Thebesii])
is a semicircular fold of the lining membrane of the auricle, protecting
the orifice of the coronary sinus. It prevents the regurgitation of blood
into the sinus during the contraction of the auricle. This valve is occasionally
double.
The fossa ovalis is an oval depression corresponding to the situation of the
foramen ovale in the fretus. It is situated at the lower part of the septum atriorum,
above and to the left of the orifice of the postcava. In foetal life an opening,
the foramen ovale, exists at this point between the two auricles; almost imme-
diately after birth the valve-like edge is pressed down by the increased pressure
in the left auricle, and by the tenth day it passes to the annulus and closes the
opening.
The annulus ovalis (limbus fossae ovalis [Vieussenii]) is a prominent oval margin
which surrounds anteriorly and superiorly the fossa ovalis. It is most distinct
above and at the sides; below, it is deficient. A small slit-like valvular opening
is occasionally found, at th^ upper margin of the fossa ovalis, which leads upward
beneath the annulus into the left auricle, and is the remains of the aperture between
the two auricles in the foetus.
570 THE BLOOD-VASCULAR SYSTEM
The tubercle of Lower (tuberculum intervenosum [Loweri]) is a small projection
on the interauricular septum between the fossa ovalis and the opening of the
precava. It is most distinct in the hearts of quadrupeds; in man it is scarcely
visible. It was supposed by Lower to direct the blood from the precava toward
the auriculo-ventricular opening.
The Left Fore-chamber or Auricle (atrium sinistrum) is rather smaller than the
right; its walls are thicker, measuring about one line and a half; and it consists,
like the right, of two parts, a principal cavity, or sinus, and an auricular appendix.
The sinus is cuboidal in form, and concealed in front by the pulmonary artery
and aorta; internally, it is separated from the right auricle by the auricular septum
(septum atriorum); behind, it receives on each side two pulmonary veins, being
free in the rest of its extent.
The left auricular appendix (auricula sinistra) is somewhat constricted at its
junction with the auricle; it is longer, narrower, and more curved than that of
the right side, and its margins are more deeply indented, presenting a kind of
foliated appearance. Its direction is forward and toward the right side, over-
lapping the root of the pulmonary artery.
Within the auricle the following parts present themselves for examination:
The openings of the four pulmonary veins.
Auriculo-ventricular opening.
Musculi pectinati.
Foramina Thebesii.
The pulmonary veins, four in number, open, two into the right and two into
the left side of the auricle. The two left veins frequently terminate by a common
opening. They are not provided with valves.
The auriculo-ventricular opening or mitral orifice (ostium venosum ventriculi
sinistri) is the large oval aperture of communication between the left auricle
and the left ventricle. It is rather smaller than the corresponding opening on
the opposite side (see note, page 571).
The musculi pectinati are fewer in number and smaller than on the right side;
they are confined to the inner surface of the auricular appendix.
On the inner surface of the auricular septum may be seen a lunated impres-
sion bounded below by a crescentic ridge the concavity of which is turned upward.
The depression is just above the fossa ovalis in the right auricle. The inner
surface of the auricle shows foramini Thebesii and venae minimis cordis.
To examine the interior of the left ventricle, make an incision a little to the left of the anterior
interventricular groove from the base to the apex of the heart, and carry it up from thence,
a little to the left of the posterior interventricular groove, nearly as far as the auriculo-ventricular
groove.
The ventricular portion of the heart is conical in shape with its base extending
backward and upward and fitting against the atrii of the auricles. Its apex
constitutes the apex of the heart (apex cordis) and extends to the fifth intercostal
space three and a quarter inches to the left of the middle line. The ventricles
are thick and muscular and have an antero -superior surface (fades sternalis) and
'a postero-inferior surface (fades diaphragmatic 2) and two borders, a right and a
left border. The antero-superior surface is composed mainly of the right ven-
tricle; coursing on this surface, nearer the left border than the right from the
auriculo-ventricular groove to the apex, is the anterior interventricular groove
(sulcus longitudinalis anterior). The inferior surface rests on the diaphragm and
is chiefly made by the left ventricle ; it is also traversed by a groove called the
inferior or posterior interventricular groove (sulcus longitudinalis posterior). The
two grooves meet in a groove (indsura apids cordis) at the right side of _ the
THE HEART 571
apex of the heart. Of the two borders of the ventricular portion the right is
sharp and thin (margo acuius) and is a continuation of the sulcus terminalis of
the base of the heart. It extends from right to left. The left border is thick
and rounded (margo obtusus). The base of the ventricles is perforated by four
large openings, namely, the aorta, the pulmonary artery, the right and left
auriculo-ventricular openings.
The Right Ventricle (ventriculus dexter) is triangular in form, and extends
from the right auricle to near the apex of the heart. Its antero-superior surface
is rounded and convex, and forms the larger part of the front of the heart. Its
inferior surface is flattened, rests upon the Diaphragm, and forms only a small
part of the back of the heart. Its posterior wall is formed by the partition between
the two ventricles, the interventricular septum (septum ventriculorum) , so that a
transverse section of the cavity presents a semilunar outline. The surface of
the septum is convex and bulges into the cavity of the right ventricle. The
upper and inner angle of the ventricle is prolonged into a conical pouch, the
infundibulum (conus arteriosus}, from which the pulmonary artery arises. The
balance of the ventricle, the body, is the portion into which the auriculo-
ventricular orifice opens. The conus arteriosus is marked off from the body of
the ventricle by a muscular projection (crista supraventricularis) . The walls of
the right ventricle are thinner than those of the left, the proportion between them
being as 1 to 3. The wall is thickest at the base, and gradually becomes thinner
toward the apex.
To examine the interior of the right ventricle, its anterior wall should be turned downward
and to the right in the form of a triangular flap. This is accomplished by making two incisions:
(1) from the pulmonary artery to the apex of the ventricle parallel to, but a little to the right
of, the anterior interventricular furrow; (2) another, starting from the upper extremity of the
first and carried outward parallel to, but a little below, the auriculo-ventricular furrow, care
being taken not to injure the auriculo-ventricular valve.
The following parts present themselves for examination:
^ . f Auriculo-ventricular.
mgs 1 Opening of the pulmonary artery.
( Tricuspid.
Valves ~\ o -i
I Semilunar.
And a muscular and tendinous apparatus connected with the tricuspid valve:
Columnar carnese. Chorda? tendineae.
The right auriculo- ventricular opening or the tricuspid orifice (ostium venosum ven-
triculi dextri) is the large oval aperture of communication between the auricle and
ventricle. It is situated at the base of the ventricle, near the right border of
the heart. It is about an inch and a half in diameter,1 oval from side to side,
surrounded by a fibrous ring and covered by the lining membrane of the heart;
it is considerably larger than the corresponding aperture on the left side, being
sufficient to admit the ends of four fingers. It is guarded by the tricuspid
valve.
The opening of the pulmonary artery (ostium arteriosum) is circular in form,
and is situated at the summit of the conus arteriosus, close to the ventricular
septum. It is placed above and on the left side of the auriculo-ventricular
1 In the Pathological Transactions, vol. vi. p. 119, Dr. Peacock has given some careful researches upon the
weight and dimensions of the heart in health and disease. He states, as a result of his investigations, that
in the healthy adult heart the right auriculo-ventricular aperture has a mean circumference of 54.4 lines, or
420/24 inches; the left auriculo-ventricular aperture a mean circumference of 44.3 lines, or 34/o4 inches; the pulmonic
orifice of 40 lines, or 3':t/24 inches; and the aortic orifice of 35.5 lines, or 3--/24 inches; but the dimensions of the
orifices varied greatly in different cases, the right auriculo-ventricular aperture having a range of from 40 to 50
line?, and the others in the same proportion. — ED. of 15th English edition.
572 THE BLOOD -VASCULAR SYSTEM
opening, upon the anterior aspect of the heart. Its orifice is guarded by the
pulmonary semilunar valves.
The tricuspid valve (vcdvida tricuspidalis) consists of three segments or cusps
(cuspides) of a triangular or trapezoidal shape, each formed by a duplicature of
the lining membrane of the heart, strengthened by a layer of fibrous tissue, which
contains, according to Kiirschner and Senac, muscular fibres. These segments
are connected by their bases to the oval fibrous ring surrounding the auriculo-
ventricular orifice (annulus fibrosus dexter), and by their sides with one another,
so as to form a continuous annular membrane, which is attached round the
margin of the auriculo-ventricular opening, their free margins and ventricular
surfaces affording attachment to a number of delicate tendinous cords, the
chordae tendineae. The largest and most movable segment is placed toward
the left side of the auriculo-ventricular opening, and is interposed between that
opening and the inf undibulum ; hence it is called the left or infundibular cusp
(cuspis medialis). Another segment corresponds to the right part of the front
of the ventricle, the right or marginal cusp (cuspis anterior), and a third to its
posterior wall, the posterior or septal cusp (cuspis posterior). The central part of
each segment is thick and strong: the lateral margins are thin and translucent.
The chordae tendineae are connected with the adjacent margins of the principal
segments of the valve, and are further attached to each segment in the following
manner: 1. Three or four reach the attached margin of each segment, where
they are continuous with the auriculo-ventricular tendinous ring. 2. Others, four
to six in number, are attached to the central thickened part of each segment. 3.
The most numerous and finest are connected with the marginal portion of each
segment.
The columnas carneae (trabeculae carneae) are the rounded muscular columns
which project from nearly the whole of the inner surface of the ventricle, except-
ing near the opening of the pulmonary artery, where the wall is smooth. They
may be classified, according to their mode of connection with the ventricle, into
three sets. The first set merely forms prominent ridges on the inner surface of
the ventricle, being attached by their entire length on one side, as well as by
their extremities. The second set are attached by their two extremities, but are
free in the rest of their extent ; while the third set (musculi papillares) are attached
by one extremity to the wall of the heart, the opposite extremity giving attach-
ment to the chordae tendineae. There are two papillary muscles, the anterior and
the posterior: of these, the anterior is the larger; its chordae tendinae are connected
with the right and left segments of the tricuspid valve. The posterior is not
always single, but sometimes consists of two or three muscular columns; its
chordae tendineae are connected with the posterior and the right segments of the
tricuspid valve. In addition to these, some few chordae may be seen springing
directly from the ventricular septum, or from small eminences on it, and passing
to the left and posterior segments. A fleshy band, well marked in the ox and
some other animals, is frequently seen passing from the base of the anterior
papillary muscle to the interventricular septum. From its attachments it may
assist in preventing overdistention of the auricle, and so has been named the
moderator band.
The right auriculo-ventricular orifice allows the blood to pass freely from the
right auricle into the right ventricle, and it will be noted that the surface of the
tricuspid valve next the blood-current is quite smooth. When the right ventricle
contracts to force the blood into the pulmonary artery, the segments of the tri-
cuspid valve come together and close the auriculo-ventricular opening, and so
prevent the blood from passing back into the auricle. The papillary muscles
and chordae tendineae moor the segments of the valve and prevent their being
forced through into the auricle by the weight of blood behind them.
THE HEART 573
The semilunar valves (vahndae semilunares a. pulmonalis) , three in number,1
guard the orifice of the pulmonary artery. They consist of three semicircular
folds : two of which are anterior and one of which is posterior. They are formed
by duplicatures of the lining membrane of the ventricle, strengthened by fibrous
tissue. They are attached, by their convex margins, to the wall of the artery, at its
junction with the ventricle, the straight border being free, and directed upward in
the lumen of the vessel. The free margin of each is somewhat thicker than the rest
of the valve, is strengthened by a bundle of tendinous fibres, and presents, at its
middle, a small projecting thickened nodule, consisting of bundles of interlacing
connective-tissue fibres with branched connective-tissue cells and some few elastic
fibres. Such a nodule is called the corpus Arantii or body of Arangi (noduli valvu-
larum semilunarium [Arantii]). From this nodule tendinous fibres radiate through
the valve to its attached margin, and these fibres form a constituent part of its
substance throughout its whole extent, excepting two narrow lunated portions, the
lunulae (lunulae valvularum semilunarium), placed one on each side of the nodule
immediately adjoining the free margin; here the valve is thin, and formed merely
by the lining membrane. During the passage of the blood along the pulmonary
artery these valves are opened, and the course of the blood along the tube is unin-
terrupted ; but during the ventricular diastole, when the current of blood along the
pulmonary artery is checked and partly thrown back by its elastic walls, these
valves become immediately expanded, and effectually close the entrance of the
tube. When the valves are closed, the lunated portions of each are brought into
contact with one another by their opposed surfaces, the three corpora Arantii
filling up the small triangular space that would be otherwise left by the approxi-
mation of the three semilunar valves.
Between the semilunar valves and the commencement of the pulmonary artery
are three pouches or dilatations, one behind each valve. These are the pulmonary
sinuses of Valsalva. Similar sinuses exist between the semilunar valves and the
commencement of the aorta; they are larger than the pulmonary sinuses. The
blood, in its regurgitation toward the heart, finds its way into these sinuses, and
so shuts down the valve-flaps.
In order to examine the interior of the left auricle, make an incision on the posterior surface
of the auricle from the pulmonary veins on one side to those on the other, the incision being
carried a little way into the vessels. Make another incision from the middle of the horizontal
one to the appendix.
The Left Ventricle (ventriculus sinister) is longer and more conical in shape
than the right ventricle, and on transverse section its cavity presents an oval or
nearly circular outline. It forms a small part of the anterior surface of the heart
and a considerable part of its posterior surface. It also forms the apex of the
heart by its projection beyond the right ventricle. Its walls are much thicker
than those of the right side, the proportion being as 3 to 1 . They are thickest oppo-
site the widest part of the ventricle, becoming gradually thinner toward the base,
and also toward the apex, which is the thinnest part.
The following parts present themselves for examination :
~ . J Auriculo- ventricular. f Mitral.
Openings \ Aortic Valves \ Semikmar<
Chordae tendinese. Columnee carneae.
The left auriculo-ventricular opening or the mitral orifice (ostium venosum ven-
triculi sinistri) is placed below and to the left of the aortic orifice. It is a little
1 The pulmonary semilunar valves have been found to be two in number instead of three (Dr. Hand, of St.
uli*
me _|jumiuiiuiy Memuuimr vaive* nave ueeii louiiu MI ue iwo in iiuinoer mtsieau 01 inree
Paul, Minn., in North Western Med. and Surg. Journ., July, 1873), and the same variety is more frequently
noticed in the aortic semilunar valves. — ED. of 15th English edition.
574
THE BLOOD -VASCULAR SYSTEM
smaller than the corresponding aperture of the opposite side, admitting only two
fingers; but, like it, is broader in the transverse than in the antero-posterior
diameter. Its right, posterior, and left sides are surrounded by a dense horseshoe-
shaped fibrous ring (annulus fibrosus sinister) . The orifice is guarded by the
mitral valves, which are covered with endocardium.
The aortic opening (ostium arteriosum) is a circular aperture, in front and to
the right side of the auriculo-ventricular opening, from which it is separated by
one of the segments of the mitral valve. Its orifice is guarded by the semilunar
valves. The portion of the ventricle immediately below the aortic orifice is often
termed the aortic vestibule of Sibson. It possesses fibrous instead of muscular
walls, and so does not collapse during the ventricular diastole; it thus gives space
for the segments of the aortic valve during its closure.
Bristle passed through left
auriculo-ventricular opening.
Passed through aortic opening.
FIG. 375. — The left auricle and ventricle laid open, the posterior walls of both being removed.
The mitral or bicuspid valve (valvula bicuspidalis) is attached to the circumfer-
ence of the auriculo-ventricular orifice in the same way that the tricuspid valve is
on the opposite side. It is formed by a duplicature of the lining membrane,
strengthened by fibrous tissue, and contains a few muscular fibres. It is larger
in size, thicker, and altogether stronger than the tricuspid, and consists of two
segments of unequal size. The larger segment, the anterior or aortic cusp (cuspis
anterior) , is placed in front and to the right between the auriculo-ventricular and
aortic orifices, the smaller, the posterior or marginal cusp (cuspis posterior), is
placed to the left and behind the opening, close to the wall of the ventricle. Two
smaller segments are usually found at the angles of junction of the larger. The
mitral valve-flaps are furnished with chordae tendinese, the mode of attachment
of which is precisely similar to those on the right side; but they are thicker,
stronger, and less numerous.
The aortic semilunar valves (valvulae semilunares aortae) surround the orifice of
the aorta; one is posterior (valvula semilunaris posterior); one right (valvula
THE HEART
575
semilunarix dc.rfra) , and one left (valvula semilunaris sinistra) : they are similar in
structure and in their mode of attachment to those of the pulmonary artery. They
are, however, larger, thicker, and stronger than those of the right side ; the lunulae
are more distinct and the corpora Arantii larger and more prominent. Opposite
each segment the wall of the aorta presents a slight dilatation or bulging, the
sinus of Valsalva,
The columns carneae admit of a subdivision into three sets, like those upon
the right side; but they are smaller, more numerous, and present a dense inter-
lacement, especially at the apex, and upon the posterior wall. Those attached by
one extremity only, the musculi papillares, are two in number, being connected
•ilmonary
artery.
FIG. 376. — Section of the heart, showing the interventricular septum.
one to the anterior, the other to the posterior wall; they are of large size, and
terminate by free rounded extremities, from which the chordae tendineae arise.
The septum between the two ventricles (septum ventriculorum) is thick and
muscular, especially below (Fig. 376) . At its upper part it suddenly tapers off,
becomes destitute of muscular fibres, and consists only of fibrous tissue, covered
by two layers of endocardium; and on the right side also covered, during dias-
tole, by one of the flaps of the tricuspid valve. This upper portion is termed
the undefended or membranous part of the septum (septum membranaceum ven-
triculorum), and is continued upward and forms the septum between the
aortic vestibule and the right auricle. It is derived from the lower part of
the aortic septum of the foetus, and an abnormal communication may exist at
this part, owing to defective development of this septum.
57u
THE BLOOD- VASCULAR SYSTEM
Structure of the Heart. — The heart is a hollow muscular organ, and its walls
are divisible into three layers: the endocardium, myocardium, and epicardium or
visceral layer of the pericardium (page 562).
The Endocardium is the lining membrane of the cavities of the heart. It is
decidedly thinner than the epicardium. It is composed of endothelial cells resting
upon a connective-tissue membrane which contains unstriated muscle cells and
elastic tissue. This connective-tissue membrane of the endocardium is attached
to the myocardium by loose elastic tissue which contains blood-vessels and nerves.
The endothelial layer of the endocardium is continuous with the endothelial coat
of the blood-vessels which pass to and emerge from the heart. The endocar-
dium is more opaque on the left than on the right side of the heart, thicker in the
auricles than in the ventricles, and thickest in the left auricle. It is thin on the
musculi pectinati and on the columnae carnese, but thicker on the smooth parts of
the auricular and ventricular walls and on the tips of the musculi papillares.
The Fibrous Rings (annuli fibrosi) surround the auriculo-ventricular and arterial
orifices; they are stronger upon the left than on the right side of the heart. The
auriculo-ventricular rings serve for the attachment of the muscular fibres of the
auricles and ventricles, and also for the mitral and tricuspid valves; the ring on the
RIGHT AURICULO-
VENTRICULAR ORIFICE
PULMONA
OR
LEFT AURICULO- RIGHT
VENTRICULAR ORIFICE NODULE
FIG. 377. — Fibrous bones at the base of the ventricles. (Poirier and Charpy.)
left side is closely connected by its right margin with the aortic arterial ring. Be-
tween these and the right auriculo-ventricular ring is a mass of fibrous tissue, and in
some of the larger animals, as the ox and elephant, a nodule of bone, the os cordis.
The fibrous rings surrounding the arterial orifices serve for the attachment of
the great vessels and semilunar valves. Each ring receives, by its ventricular
margin, the attachment of the muscular fibres of the ventricles; its opposite margin
presents three deep semicircular notches, within which the middle coat of; the
artery (which presents three convex semicircular segments) is firmly fixed, the
attachment of the artery to its fibrous ring being strengthened by the thin cellular
coat and serous membrane externally and by the endocardium within. It is
opposite the margins of these semicircular notches, in the arterial rings, that the
endocardium by its reduplication forms the semilunar valves, the fibrous structure
of the ring being continued into each of the segments of the valve at this part.
The middle coat of the artery in this situation is thin, and the sides of the vessel are
dilated to form the sinuses of Valsalva.
The Myocardium is composed of muscle fibres. The muscle fibres, though striated ,
are involuntary and constitute a special type called cardiac fibres. Cardiac fibres
THE HEART 577
are shorter than ordinary striated muscle fibres, many of the cells are oblong and
the nuclei are centrally placed. During the first year of life, and occasionally even
in adult life, certain peculiar fibres are found beneath the elastic tissue which
attaches the endocardium to the myocardium. These peculiar fibres are called
the fibres of Purkinje. The striation in these cells is peripheral only. Between
individual fibres and between bundles of fibres of cardiac muscle is connective
tissue carrying capillaries.
The Muscular Structure of the heart consists of bands and layers of fibres which
present an exceedingly intricate interlacement. They are of a deep red color and
marked with transverse striae. The arrangement of the fasciculi varies in different
parts of the heart. It requires elaborate care to demonstrate the layers, and it is
more than probable that some of those described are really artificially produced.
The fasciculi of the heart admit of a subdivision into two groups, those of the
auricles and those of the ventricles. It was long thought that auricular fasciculi
were entirely separate from the ventricular fasciculi. It is now known that there is
a direct connection by means of the auriculo-ventricular fasciculus of His (see
below).
FIG. 378. — The arrangement of the muscles of the auricles. (Poirier and Charpy.)
FIBRES OF THE AURICLES (Fig. 378). — These are disposed in two layers — a
superficial layer common to both cavities, and a deep layer proper to each. The
superficial fibres are more distinct on the anterior surface of the auricles, across
the bases of which they run in a transverse direction, forming a thin but incomplete
layer. Some of these fibres pass into the septum atriorum. The internal or deep
fibres proper to each auricle consist of two sets, looped and annular fibres. The
looped fibres pass upward over each auricle, being attached by two extremities
to the corresponding auriculo-ventricular rings in front and behind. The annular
fibres surround the whole extent of the auricular appendices, and are continued
upon the walls of the venae cavse and coronary sinus on the right side, and upon
the pulmonary veins on the left side, at their connection with the heart. In the
appendices they interlace with the longitudinal fibres.
FIBRES OF THE VENTRICLES. — These are arranged in an exceedingly complex
manner, and the accounts given by various anatomists differ considerably. This
is probably due partly to the fact that the various layers of muscular fibres of
which the heart is said to be composed are not independent, but their fibres are
interlaced to a considerable extent, and therefore any separation into layers must
be to a great extent artificial; and also partly to the fact, pointed out by Henle,
that there are varieties in the arrangement due to individual differences. If the
epicardium and the subjacent fat are removed from a heart which has been sub-
37
578
THE BLOOD-VASCULAR SYSTEM
jected to prolonged boiling, so as to dissolve the connective tissues, the superficial
fibres of the ventricles will be exposed. They will be seen to commence at the base
of the heart, where they are attached to the tendinous rings around the orifices,
and to pass obliquely downward toward the apex, with a direction from right to
left. At the apex the fibres turn suddenly inward into the interior of the ventricle,
forming what is called the vortex (Fig. 379). On the back of the heart it will be
seen that the fibres pass continuously from one ventricle to. the other over the inter-
ventricular groove; and the same thing will be noticed on the front of the heart at
the upper and lower end of the anterior interventricular groove, but in the middle
portion of this groove the fibres passing from one ventricle to the other are inter-
rupted by fibres emerging from the septum along the groove; many of the super-
ficial fibres pass in also at this groove to the septum. The vortex is produced,
as stated above, by the sudden turning
inward of the superficial fibres in a
peculiar spiral manner into the deepest
portion of the wall of the ventricle.
Those fibres which descended on the
posterior surface of the heart enter the
left ventricle at the vortex, and, ascend-
ing, form the posterior part of the inner
layer of muscular fibres lining this
cavity and the right (posterior) mus-
culus papillaris; those fibres which
descend on the front of the heart to
reach the apex also pass, at the vortex,
into the interior of the ventricle, where
they form the remainder of the inner-
most layer of the ventricle and the left
(anterior) musculus papillaris. The
fibres forming the inner layer of the wall of the ventricle ascend to be attached
to the fibrous rings around the orifices.
By dissection these superficial fibres may be removed as a thin stratum, and it
will then be found that the ventricles are made up of oblique fibres (Fig. 380), super-
imposed in layers one on the top of another, and assuming gradually a less oblique
direction as they pass to the middle of the thickness of the ventricular wall, so that
in the centre of the wall the fibres are transverse. Internal to this central transverse
layer the fibres become oblique again, but in the opposite direction to the external
ones. This division into distinct layers is, however, to a great extent artificial, as the
fibres pass across from one layer to another, and have therefore to be divided in
the dissection, and the change in the direction of the fibres is very gradual. These
oblique fibres commence above at the fibrous rings at the base of the heart, and,
descending toward the apex, they enter the septum near its lower end. In the
septum the fibres which form the left ventricle may be traced in three directions:
1. Some pass upward to be attached to the central mass of fibrous tissue. 2.
Others pass through the septum to become continuous with the fibres of the right
ventricle. 3. The remainder pass through the septum to encircle the ventricle
as annular fibres. Of the fibres of the right ventricle, some on entering the septum
pass upward to be attached to the central mass of fibrous tissue; some, entering
the septum from behind, pass forward to become continuous with the fibres on
the anterior surface of the left ventricle; and others, entering in front, pass back-
ward to join the fibres on the posterior wall of the left ventricle. The septum
therefore consists of three varieties of fibres — viz., annular fibres, special to the left
ventricle; ascending fibres, derived from both ventricles and ascending through
the septum to the central fibro-cartilage ; and decussating fibres, derived from the
FIG. 379.— -The muscular arrangement of the apex
of the heart. (Poirier and Charpy.)
THE HEART
579
anterior wall of one ventricle and passing to the posterior wall of the other ven-
tricle, or from the posterior wall of the right ventricle and passing to the anterior
wall of the left. In addition to these fibres there are a considerable number
which appear to encircle both ventricles and which pass across the septum without
turning into it.
FIG. 380. — The muscular arrangement of the ventricle. (Poirier and Charpy.)
THE AURICULO-VENTRICULAR FASCICULUS, OR THE BUNDLE OF His. — The only
direct connection between the muscle of the auricles and the muscle of the ventri-
cles is the muscular bundle described by His and known as the auriculo-ventricular
fasciculus. It takes origin from the posterior wall of the right auricle close to the
auricular septum. This bundle descends from its point of origin and reaches the
upper margin of the ventricular septum. At a portion of this margin which is dis-
tinctly muscular it takes a turn forward, crosses the septum between the mem-
branous and muscular areas, and disappears in the ventricular muscle. A wave
of contraction starts in the auricles and is transmitted to the ventricles by the
bundle of His. If this bundle is cut or clamped, heart block occurs, because the
stimulus is no longer transmitted from the auricle to the ventricle.
Erlanger showed that all degrees of heart block can be induced by compression
of the bundle. Erlanger says that, "as a rule, the ventricles take on a constant slow
rate at the moment complete heart block is established." The auricles beat nor-
mally or more rapidly than normally.
Stokes-Adams disease is a condition of heart block produced by a lesion of the
auriculo-ventricular bundle. This was demonstrated by Erlanger.
In Stokes-Adams disease there are attacks of vertigo or syncope, perhaps with
epileptiform convulsions, and in these attacks the ventricles beat at less than the
normal rate, and the auricles normally or more frequently than normally.
580 THE BLOOD-VASCULAR SYSTEM
Vessels and Nerves. — The arteries supplying the heart are the right and left
coronary from the aorta. Branches from the coronary vessels supply the mus-
cular structure, the subendocardial, and the subepicardial tissue. There are no
vessels in the endocardium. The valves contain no vessels unless they contain
muscle, in which case minute vessels enter them. There are numerous capillary
networks about the muscular fibres.
The veins accompany the arteries. They are: the anterior or great, the posterior,
the left, and the anterior cardiac veins, the right or small, and the left or great,
coronary sinuses. The coronary sinus receives most of the veins of the heart and
empties into the right auricle. Some few small veins open directly into the right
and left auricles and into the ventricles. They are the venae minimse cordis. The
oblique vein of the left auricle is known as the oblique vein of Marshall.
The lymphatics are arranged in two networks: one in the muscle beneath the
endocardium, another in the muscle beneath the epicardium. The deep empties
into the superficial network, the anterior collecting trunks from the subepicardial
network pass to the tracheo-bronchial glands. The posterior collecting trunk
terminates in the same group of glands.1
The nerves are derived from the superficial and deep cardiac plexuses, and from
these plexuses obtain fibres of the vagus, accessory, and sympathetic. The super-
ficial cardiac plexus lies under the arch of the aorta. The deep cardiac plexus
is in front of the tracheal bifurcation. The nerves from the plexuses are freely
distributed both on the surface and in the substance of the heart, the separate
filaments being furnished with small ganglia.
Surface Form. — In order to show the extent of the heart in relation to the front of the chest,
draw a line from the lower border of the second left costal cartilage, one inch from the sternum,
to the upper border of the third right costal cartilage, half an inch from the sternum. This
represents the base-line or upper limit of the organ. Take a point an inch and a half below
and three-quarters of an inch internal to the left nipple — that is, about three and a half inches
to the left of the median line of the body. This represents the apex of the heart. Draw a line
from this apex-point, with a slight convexity downward, to the junction of the seventh right
costal cartilage to the sternum. This represents the lower limit of the heart. Join the right
extremity of the first line — that is, the base-line — with the right extremity of this line — that is,
to the seventh right chondro-sternal joint — with a slight curve outward, so that it projects about
an inch and a half from the middle line of the sternum. Lastly, join the left extremity of the
base-line and the apex-point by a line curved slightly to the left.
The position of the various orifices is as follows — viz., the pulmonary orifice is situated in
the upper angle formed by the articulation of the third left costal cartilage with the sternum;
the aortic orifice is a little below and internal to this, behind the left border of the sternum,
close to the articulation of the third left costal cartilage to this bone. The left auriculo-ventric-
ular opening is behind the sternum, rather to the left of the median line, and opposite the fourth
costal cartilages. The right auriculo-ventricular opening is a little lower, opposite the fourth
interspace and in the middle line of the body (Fig. 366).
A portion of the area of the heart thus mapped out is uncovered by lung, and therefore
gives a dull note on percussion; the remainder, being overlapped by the lung, gives a more or
less resonant note. The former is known as the area of superficial cardiac dulness; the latter
as the area of deep cardiac dulness. The area of superficial cardiac dulness is included between
a line drawn from the centre of the sternum, on a level with the fourth costal cartilages, to the
apex of the heart and a line drawn from the same point down the lower third of the middle line
of the sternum. Below, this area merges into the dulness which corresponds to the liver. Dr.
McClellan states that the area of superficial cardiac dulness may be mapped out " by draw-
ing a line from the middle of the sternum opposite the fourth left costal cartilage to the point
of junction of the fifth rib and its cartilage, and from this point horizontally back to the mid-
sternal line."
Surgical Anatomy.— Wounds of the heart are often immediately fatal, but not necessarily
so. They may be non-penetrating, when death may occur from hemorrhage, if one of the coro-
nary vessels has been wounded, or subsequently from pericarditis; or, on the other hand, the
patient may recover. Even a penetrating wound is not necessarily fatal, if the wound is a small
one. An attempt should be made to save the patient by means of a surgical operation. A
1 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf.
THE HEART 581
trap-door flip comprising the whole thickness of the thoracic wall should be made. The hinges
of the trap-door are the rib cartilages. The pericardium is exposed and opened freely, clots are
removed, the wound in the heart is sought for, and when discovered is sutured. In a pene-
trating wound the sutures include the whole thickness of the heart, except the endocardium.
Interrupted sutures should be used, and each one had better be tied during diastole. A number
of successful operations of this character have been performed.
Peculiarities in the Vascular System of the Foetus (Fig. 382).
The chief peculiarities in the heart of the foetus are the direct communication
between the two auricles through the foramen ovale, and the large size of the
Eustachian valve. There are also several minor peculiarities. Thus, the position
of the heart is vertical until the fourth month, when it commences to assume an
oblique direction. Its size is also very considerable as compared with the body,
the proportion at the second month being 1 to 50; at birth it is as 1 to 120; whilst
in the adult the average is about 1 to 160. At an early period of foetal life the
auricular portion of the heart is larger than the ventricular, the right auricle being
more capacious than the left; but toward birth the ventricular portion becomes
the larger. The thickness of both ventricles is at first about equal, but toward
birth the left becomes much the thicker of the two.
CONUS
ARTERIOSUS
VALVE OF
FORAMEN OVALE
VALVE OF AURICULO-VENTRICULAR
CORONARY SINUS OPENING
FIG. 381. — The right auricle of a foetal heart (eighth month). Enlarged. (Spalteholz.)
The foramen ovale (Fig. 381) is situated at the lower and back part of the auric-
ular septum, forming a communication between the auricles. It remains as a free
oval opening until the middle period of foetal life. About this period a fold grows
up from the posterior wall of the auricle to the left of the foramen ovale, and
advances over the opening so as to form a sort of valve, which allows the blood
to pass only from the right to the left auricle, and not in the opposite direction.
The Eustachian valve (Fig. 381) is directed upward on the left side of the open-
ing of the postcava (inferior vena cava), and serves to direct the blood from this
vessel through the foramen ovale into the left auricle.
The peculiarities in the arterial system of the foetus are the communication
between the pulmonary artery and the descending aorta by means of the ductus
arteriosus, and the communication between the internal iliac arteries and the
placenta by means of the umbilical arteries.
582
THE BLOOD-VASCULAR SYSTEM
The Ductus Arteriosus (Fig. 382). — The ductus arteriosus is a short tube, about
half an inch in length at birth, and of the diameter of a goose-quill. In the early
condition it foros the continuation of the pulmonary artery, and opens into the
Ductus arteriosus.
'Internal iliac artery.
FIG. 382. — Plan of the foetal circulation. In this plan the figured arrows represent the kind of blood, as well
as the direction which it takes in the vessels. Thus, arterial blood is figured »— --> ; venous blood,
» >; mixed (arterial and venous) blood, » •• — • >.
descending aorta just below the origin of the left subclavian artery, and so con-
ducts the chief part of the blood from the right ventricle into this vessel. When
the branches of the pulmonary artery have become larger relatively to the ductus
arteriosus, the latter is chiefly connected to the left pulmonary artery; and the
fibrous cord (ligamentum arteriosum), which is all that remains of the ductus
arteriosus in later life, will be found to be attached to the root of that vessel.
THE HEART 583
The Umbilical Arteries. — The umbilical or hypogastric arteries arise from the
internal iliacs, in addition to the branches given off from those vessels in the
adult. Ascending along the sides of the bladder to its apex, they pass out of
the abdomen at the umbilicus and are continued along the umbilical cord to
the placenta, coiling round the umbilical vein. They carry to the placenta the
blood which has circulated in the system of the foetus.
The peculiarity in the venous system of the foetus is the communication estab-
lished between the placenta and the liver and portal vein through the umbilical
vein, and the postcava through the ductus venosus.
Foetal Circulation. -*-The blood destined for the nutrition of the foetus is
returned from the placenta to the foetus by the umbilical vein. This vein enters
the abdomen at the umbilicus, and passes upward along the free margin of the
suspensory ligament of the liver to the under surface of that organ, where it gives
off two or three branches to the left lobe, one of which is of large size, and others
to the lobus quadratus and lobulus Spigelii. At the transverse fissure it divides
into two branches: of these, the larger is joined by the portal vein and enters the
right lobe; the smaller branch continues outward, under the name of the ductus
venosus, and joins the left hepatic vein at the point of junction of that vessel with
the postcava. The blood, therefore, which traverses the umbilical vein reaches
the postcava in three different ways: the greater quantity circulates through the
liver with the portal venous blood before entering the postcava by the hepatic
veins; some enters the liver directly, and is also returned to th'e postcava by the
hepatic veins; the smaller quantity passes directly into the postcava by the junction
of the ductus venosus with the left hepatic vein.
In the postcava (inferior vena cava) the blood carried by the ductus venosus and
hepatic veins becomes mixed with that returning from the lower extremities and wall
of the abdomen. It enters the right auricle, and, guided by the Eustachian valve,
passes through the foramen ovale into the left auricle, where it becomes mixed with
a small quantity of blood returned from the lungs by the pulmonary veins. From
the left auricle it passes into the left ventricle, and from the left ventricle into
the aorta, by means of which it is distributed almost entirely to the head and
upper extremities, a small quantity being probably carried into the descending
aorta. From the head and upper extremities the blood is returned by the tributa-
ries of the precava (superior vena cava) to the right auricle, where it becomes mixed
with a small portion of the blood from the postcava (inferior vena cava). From
the right auricle it descends over the Eustachian valve into the right ventricle, and
from the right ventricle passes into the pulmonary artery. The lungs of the foetus
being inactive, only a small quantity of the blood of the pulmonary artery is dis-
tributed to them by the right and left pulmonary arteries, and is returned by the
pulmonary veins to the left auricle; the greater part passes through the ductus
arteriosus into the commencement of the descending aorta, where it becomes
mixed with a small quantity of blood transmitted by the left ventricle into the
aorta. Through this vessel it descends to supply the lower extremities and viscera
of the abdomen and pelvis, the chief portion being, however, conveyed by the
umbilical arteries to the placenta.
From the preceding account of the circulation of the blood in the foetus it will
be seen —
1. That the placenta serves the purposes of nutrition and excretion, receiving
the impure blood from the foetus, and returning it charged with additional nutri-
tive material.
2. That nearly the whole of the blood of the umbilical vein traverses the liver
before entering the postcava; hence the large size of this organ, especially at an
«arly period of foetal life.
3. That the right auricle is the point of meeting of a double current, the blood
584 THE BLOOD- VASCULAR SYSTEM
in the postcava being guided by the Eustachian valve into the left auricle, whilst
that in the precava descends into the right ventricle. At an early period of the
foetal life it is highly probable that the two streams are quite distinct, for the
postcava opens almost directly into the left auricle, and the Eustachian valve
would exclude the current along the vein from entering the right ventricle. At a
later period, as the separation between the two auricles becomes more distinct,
it seems probable that some mixture of the two streams must take place.
4. The pure blood carried from the placenta to the fretus by the umbilical vein,
mixed with the blood from the portal vein and the postcava, passes almost directly
to the arch of the aorta, and is distributed by the branches of that vessel to the
head and upper extremities; hence the large size and perfect development of
those parts at birth.
5. The blood contained in the descending aorta, chiefly derived from that
which has already circulated through the head and upper limbs, together with a
small quantity from the left ventricle, is distributed to the lower extremities;
hence the small size and imperfect development of these parts at birth.
Changes in the Vascular System at Birth.
At birth, when respiration is established, an increased amount of blood from
the pulmonary artery passes through the lungs, which now perform their office
as respiratory organs, and at the same time the placental circulation is cut off.
Almost immediately after birth the foramen ovale is closed by the valvular edge
being pressed against the annulus ovalis, the pressure being due to respiration,
which increases the pressure in the left auricle. The structures fuse, and closure
is complete by about the tenth day after birth. The valvular fold above men-
tioned becomes adherent to the margins of the foramen for the greater part of its
circumference, but above a slit-like opening is left between the two auricles which
sometimes remains persistent.
The ductus arteriosus begins to contract immediately after respiration is estab-
lished, becomes completely closed from the fourth to the tenth day, and ultimately
degenerates into an impervious cord which serves to connect the left pulmonary
artery to the descending aorta. When respiration begins, the caval opening of
the diaphragm being fixed and the balance of the muscle rising and falling, the
ductus arteriosus is compressed by the muscular structures which pass from the
diaphragm to the pericardium, is narrowed, and is finally obliterated (Forbes).
Of the umbilical or hypogastric arteries, the portion continued on to the bladder
from the trunk of the corresponding internal iliac remains pervious as the superior
vesical artery, and the part extending from the side of the bladder to the umbilicus
becomes obliterated between the second and fifth days after birth, and projects
as a fibrous cord toward the abdominal cavity, carrying on it a fold of peritoneum
and separating two of the fossae of the peritoneum spoken of in the section on the
surgical anatomy of direct inguinal hernia.
The umbilical vein and the ductus venosus become completely obliterated
between the second and fifth days after birth, and ultimately dwindle to fibrous
cords, the former becoming the round ligament of the liver, the latter the fibrous
cord, which in the adult may be traced along the fissure of the ductus venosus.
THE ARTERIES.
THE Arteries are cylindrical tubular vessels which serve to convey blood from
both ventricles of the heart to every part of the body. These vessels were named
arteries (dyp, air; rypetv, to contain) from the belief entertained by the ancients
that they contained air. To Galen is due the honor of refuting this opinion; he
showed that these vessels, though for the most part empty after death, contain
blood in the living body.
The distribution of the systemic arteries is like a highly ramified tree, the
common trunk of which, formed by the aorta, commences at the left ventricle of
the heart, the smallest ramifications corresponding to the circumference of the
body and the contained organs. The arteries are found in nearly every part of
the body, with the exception of the hairs, nails, epidermis, cartilages, and cornea;
and the larger trunks usually occupy the most protected situations, running, in
a limb, along the flexor side, where they are less exposed to injury.
There is considerable variation in the mode of division of the arteries: occa-
sionally a short trunk subdivides into several branches at the same point, as
we observe in the coeliac and thyroid
axes; or the vessel may give off several A B
branches in succession, and still con-
tinue as the main trunk, as is seen in
the arteries of thefimbs; but the usual
division is dichotomous ; as, for instance,
the aorta dividing into the two common
iliacs, and the common carotid into the
external and internal carotids.
The branches of arteries arise at very
variable angles: some, as the superior
intercostal arteries from the aorta, arise
at an obtuse angle: others, as the lumbar
arteries, at a right angle; or, as the
spermatic, at an acute angle. An artery
from below the point at which a branch
is given off is smaller in size than be-
fore. It retains a uniform diameter
until a second branch is derived from
it. A branch of an artery is smaller
than the trunk from which it arises ; but
if an artery divides into two branches,
the combined area of the two vessels is, in nearly every instance, somewhat
greater than that of the trunk; and the combined area of all the arterial branches
greatly exceeds the area of the aorta; so that the arteries collectively may be
regarded as a cone, the apex of which corresponds to the aorta, the base to the
capillary system.
The arteries, in their -distribution, communicate with one another, forming
what is called an anastomosis (dvd, between; ffropa, mouth) or inosculation (Fig.
383) ; and this communication is very free between the larger as well as between the
. (585)
FIG. 383. — Diagram showing the anastomosis of
arteries. (Poirier and Charpy.)
586
THE BLOOD -VASCULAR SYSTEM
e, j
smaller branches. An anastomosis between trunks of equal size is found where
great activity of the circulation is requisite, as at the base of the brain ; here the
two vertebral arteries unite to form the basilar, and the two internal carotid
arteries are connected by a short communicating trunk; it is also found in the
abdomen, the intestinal arteries having very ample anastomoses between their
larger branches. In the limbs the anastomoses are most numerous and of
largest size around the joints, the branches of an artery above inosculating
with branches from the vessels below; these anastomoses are of considerable
interest to the surgeon, as it is by their enlargement that a collateral circula-
tion is established after the application of a ligature to an artery for the cure
of aneurism. The smaller branches of arteries anastomose more frequently
than the larger, and between the smallest twigs these inosculations become so
numerous as to constitute a close network
that pervades nearly every tissue of the body.
A terminal artery is one which forms no
anastomoses. Such vessels are found in the
brain, spleen, kidneys, lungs, and mesen-
tery.
Throughout the body generally the larger
arterial branches pursue a perfectly straight
course, but in certain situations they are tor-
tuous ; thus the facial arteries in their course
over the face, and the arteries of the lips,
are extremely tortuous in their course, to
accommodate themselves to the movements
of the parts. The uterine arteries are also
tortuous, to accommodate themselves to the
increase of size which the organ undergoes
during pregnancy. Afain, the internal
carotid and vertebral arteries, previous to
their entering the cavity of the skull, de-
scribe a series of curves, which are evidently
intended to diminish the velocity of the cur-
rent of blood by increasing the extent of
surface over which it moves and adding to
the resistance which is produced by friction.
The arteries are dense in structure, of
considerable strength, highly elastic, and,
when divided, they preserve, although empty,
their cylindrical form.
Histology of the Capillaries and Ar-
teries. The Capillaries (Fig. 386). — The
capillaries are very small endothelial tubes
which connect the venous system with the
arterial system. In diameter they vary from -g-^Vtr t° TOlFU" °f an mcn> in length
from ^V to -gijj- of an inch. The nucleated endothelial cells which constitute the
wall of a capillary are flat, irregular in outline, and are united by a cement
material. Small openings (stomata) are frequently noted between these cells,
but they are probably artifacts and do not exist during life.
The capillaries anastomose and form vast networks. When an artery is about
to become a capillary the muscular coat disappears. The endothelial coat which
constitutes the capillaries extends as a system of endothelial tubes throughout the
entire blood-vascular system. The heart is a great muscular thickening around
a portion of the system of endothelial tubes. An artery consists of an endothelial
FIG. 384. — Transverse section through a small
artery and vein of the mucous membrane of the
epiglottis of a child. Magnified about 350 diame-
ters. A, artery, showing the nucleated endothe-
lium e, which lines it: the vessel being con-
tracted, the endothelial cells appear very thick.
Underneath the endothelium is the wavy elastic
intima. The chief part of the wall of the vessel
is occupied by the circular muscle-coat m; the
staff-shaped nuclei of the muscle-cells are well
seen. Outside this is a, part of the adventitia.
This is composed of bundles of connective-tissue
fibres, shown in section, with the nuclei of the
connective-tissue corpuscles. The adventitia
gradually merges into the surrounding connective-
tissue, y, vein showing a thin endothelial mem-
brane e, raised accidentally from the intima,
which on account of its delicacy is seen as a mere
line on the media m. This latter is composed of
a few circular unstriped muscle-cells ; a, the ad-
ventitia, similar in structure to that of an artery.
(Klein and Noble Smith.)
THE ARTERIES
587
tube covered by certain accessory coats. The wall of an artery diminishes
greatly in thickness (Fig. 387) and is found to be composed of endothelial cells
and scattered unstriated muscle-fibres, covered merely by thin connective tissue
or elastic-tissue sheath (adventitia capillaris). Such a structure is known as an
arteriole or a precapillary artery. By the loss of its thin sheath of connective or
elastic tissue it becomes a capillary. A capillary takes on a thin sheath and
becomes a venule or precapillary vein. Nerves do not terminate in capillaries,
but networks of nerve-filaments often encompass these small vessels.
An artery consists of an internal coat or tunica intima, a middle coat or tunica
media, and an external coat or tunica adventitia (Figs. 384 and 385).
The Inner Coat (tunica intima) consists of endothelial cells and yellow elastic
tissue. In some cases the elastic fibres are arranged longitudinally, but, as a rule,
they form a distinct fenestrated membrane known as the fenestrated membrane of
Endothelial and snb-
endothelial layer of
~ inner coat.
'Elastic layer.
Innermost layers of
middle coat.
^ Outermost Layers of
middle coat.
__ Innermost part
outer coat.
Outer part of outer
• r coat.
FIG. 385. — Section of a medium-sized artery. (After Grtinstein.)
Henle, or the internal elastic coat. In medium-sized vessels the elastic layer of the
intima is separated from the endothelial layer by a layer of connective tissue.
In the large arteries the interposed layer of connective tissue is thicker and con-
tains elastic fibres.
The Middle Coat (tunica media) consists of muscle, elastic tissue, and white
fibrous tissue, and it is often called the elastomuscular coat. The arterioles con-
tain scattered unstriated muscle fibres. In the small arteries they constitute a
thin but definite coat. In larger arteries the muscular coat is much thicker. The
muscle is unstriated and the fibres are arranged circularly, and in the larger
vessels form layers which are separated by elastic fibres. Here and there longi-
tudinally-disposed muscle-fibres exist. The larger the artery the greater is the
amount of elastic tissue existing in the middle coat. In the aorta and in some
of the very large arteries the amount of elastic tissue exceeds the amount of
588
THE BLOOD -VASCULAR SYSTEM
muscular tissue. " In the first part of the aorta, in the pulmonary artery and in
the arteries of the retina, the muscular fibres are entirely replaced by elastic
tissue."1 The arteries within the skull have no elastic tissue in the media,
although they have some in the adventitia.
The External Coat (tunica adventitia} is called the fibrous coat. It contains
fibrous connective tissue, elastic tissues, and in some arteries fibres of unstriated
muscle arranged longitudinally. The circular elastic membrane which sepa-
rates the outer coat from the middle coat is known as the external elastic mem-
brane.
Blood-vessels of the Blood-vessel Wall.— Many small blood-vessels course in the
external and middle coats of arteries of large and of moderate size. They are
mostly in the adventitia. They may arise from the vessel to which they are dis-
FIG. 386. — Capillaries from the
mesentery of a guinea-pig after treat-
ment with solution of nitrate of silver,
a, cells; b, their nuclei.
FIG. 387. — Finest vessels on the arterial side. From the human
brain. Magnified 300 times. 1, small artery; 2, transition vessel;
3, coarser capillaries; 4, finer capillaries; a, structureless mem-
brane still with some nuclei, representative of the tunica adven-
titia; b, nuclei of the muscular fibre-cells; c, nuclei within the
small artery, perhaps appertaining to an endothelium; d, nuclei
in the transition vessels.
tributed or take origin from an adjacent vessel. These small arteries are called
the vasa vasorum. The blood is returned from the walls of the vessels by small
veins.
Lymphatics. — Distinct lymphatic vessels may exist in the adventitia, but are
not found in either of the other coats. Lymph-capillaries often surround small
blood-vessels or a small blood-vessel may lie in a perivascular lymph-space.
Nerves. — Arteries are supplied with nerves, myelinic and amyelinic. A
network of nerve-fibres may surround a vessel and usually capillaries are so sur-
rounded. In the arteries a network of nerves exists in the media. These nerves
supply the muscle-fibres and are called vasomotor nerves.
The Arterial Sheath (vagina vasis) surrounds the artery. It is composed of con-
nective tissue, and is attached to the vessel at numerous points by fibrous tissue.
1 D. J. Cunningham. Text-book of Anatomy.
THE AORTA 589
PULMONARY ARTERY (A. PULMONALIS) (Fig. 389, 393).
In the description of the arteries we shall first consider the efferent trunk of
the pulmonic circulation, the pulmonary artery, and then the efferent trunk of the
systemic circulation, the aorta and its branches.
The pulmonary artery conveys the venous blo6d from the right side of the heart
to the lungs. It is a short, wide vessel, about 2 inches in length and 1^- inches
(30 mm.) in diameter, arising from the left side of the base (conus arteriosus}
of the right ventricle, in front of the aorta. It extends obliquely upward and
backward, passing at first in front of and then to the left of the ascending
aorta, as far as the under surface of the arch, where it divides, about on a level
with the intervertebral substance between the fifth and sixth thoracic vertebrae,
into two branches of nearly equal size, the right and left pulmonary arteries.
The Right Pulmonary Artery (ramus dexter a. pulmonalis}, longer and
larger than the left, runs horizontally outward to the root of the right lung, where
it divides into two branches, of which the lower and larger supplies the middle
and lower lobes; the upper and smaller is distributed to the upper lobe. It has in
front of it the ascending aorta, the precava, and the right phrenic nerve. It has
behind it the right bronchus. Above it is the transverse portion of the arch of the
aorta. Below it is the right auricle.
The Left Pulmonary Artery (ramus sinister a. pulmonalis) , shorter and
somewhat smaller than the right, passes horizontally to the root of the left lung,
where it divides into two branches for the two lobes. In front of it and below it
are the pulmonary veins of the left side. Behind are the descending aorta and the
left bronchus. Above it are the arch of the aorta, the left recurrent laryngeal
nerve, and the ductus arteriosus. The left bronchus in a portion of its course lies
below as well as behind.
Relations. — The whole of the vessel is contained, together with the ascending
aorta, in the pericardium. It is enclosed with the aorta in a single tube of the
serous pericardium, which is continued upward upon them from the base of the
heart and connects them together. The fibrous layer of the pericardium becomes
gradually lost upon the external coats of its two branches. In front, the pulmonary
artery is separated from the anterior extremity of the second left intercostal space
by the pleura and left lung, in addition to the pericardium; it rests at first upon
the ascending aorta, and higher up lies in front of the left auricle on a plane
posterior to the ascending aorta. On each side of its origin is the appendix of
the corresponding auricle and a coronary artery, the left coronary artery passing,
in the first part of its course, behind the vessel.
The root of the left pulmonary artery is connected to the under surface of the
arch of the aorta by a short fibrous cord, the ligamentum arteriosum; this is the
remains of a vessel peculiar to foetal life, the ductus arteriosus.
The terminal branches of the pulmonary artery will be described with the
anatomy of the lung.
THE AORTA (Figs. 388, 389, 390, 393).
The aorta or arteria magna (dopnj) is the main trunk of a series of vessels which
convey the oxygenated blood to the tissues of the body for their nutrition. This
vessel commences at the upper part of the left ventricle, where it is about one and
one-eighth inches in diameter, and, after ascending for a short distance, arches
backward and to the left side, over the root of the left lung, then descends within
the thorax on the left side of the vertebral column, passes through the aortic open-
ing in the Diaphragm, and, entering the abdominal cavity, terminates, consider-
590
THE BLOOD -VASCULAR SYSTEM
ably diminished in size (about seven-tenths of an inch in diameter), opposite the
lower border of the fourth lumbar vertebra, where it divides into the right and left
common iliac arteries. Hence it is divided into the ascending aorta, the arch of
the aorta, and the descending aorta, which last is again divided into the thoracic aorta
and the abdominal aorta, from the position of these parts.
THE ASCENDING AORTA (AORTA ASCENDENS).
The ascending aorta is about two inches in length. It commences at the
upper part of the left ventricle., on a level with the lower border of the third
costal cartilage, behind the left half of the sternum ; it passes obliquely upward,
forward, and to the right, in the direction of the heart's axis, as high as the
VENA AZYGOS
MINOR
SYMPATHETIC
GANGLION
SYMPATHETIC
NERVE
FIG. 388. — Arch of the aorta and its relations. (Poirier and Charpy.)
upper border of the second right costal cartilage, describing a slight curve in
its course, and being situated, when distended, about a quarter of an inch behind
the posterior surface of the sternum. A little above its commencement it is some-
what enlarged (bulbus aortae), and presents three small dilatations, one of which is
anterior, two of which are posterior, which are called the sinuses of Valsalva (sinus
aortae). Opposite to the sinuses are attached the three semilunar valves (Fig. 376),
THE ASCENDING AORTA
591
which serve the purpose of preventing any regurgitation of blood into the cavity
of the ventricle. These valves are placed one in front and two behind. At the
union of the ascending with the transverse part of the aorta the calibre of the vessel
is increased, owing to a bulging outward of its right wall. This dilatation is termed
the great sinus of the aorta. A section of the aorta opposite this part has a some-
what oval figure; but below the attachment of the valves it is circular. This por-
tion of the aorta is contained in the cavity of the pericardium, and, together with
the pulmonary artery, is invested in a tube of serous membrane, continued on to
them from the surface of the heart.
Right vagus.
Recurrent laryngeal
Left vagus.
Left phrenic.
Thoracic duct.
FIG. 390.— Plan of
branches.
the
Fia. 389. — The arch of the aorta and its branches.
Relations. — The ascending aorta is covered at its commencement by the trunk
of the pulmonary artery and the right auricular appendix, and, higher up, is
separated from the sternum by the pericardium, the right pleura, and anterior
margin of the right lung, some loose areolar tissue, and the remains of the thymus
gland; behind, it rests upon the right pulmonary artery, left auricle, and the right
bronchus. On the right side it is in relation with the precava and right auricle;
on the left side, with the pulmonary artery.
592
THE BLOOD -VASCULAR SYSTEM
PLAN OF THE RELATIONS OF THE ASCENDING AORTA.
In front.
Pulmonary artery.
Right auricular appendix.
Pericardium.
Right pleura and lung.
Remains of the thymus gland.
Right side.
Precava.
Right auricle.
Left side.
Pulmonary artery.
Behind.
Right pulmonary artery.
Left auricle.
Right bronchus.
VAGUS NERVE
RIGHT AURICLE
FIG. 391. — Horizontal section through the sixth thoracic vertebra — upper surface of the lower segment —
showing the ascending portion of the aortic arch and the thoracic aorta.
Branches — The only branches of the ascending aorta are the coronary arteries.
They supply the heart, and are two in number, right and left, arising near the com-
mencement of the aorta, immediately above the free margin of the semilunar
valves.
The Coronary Arteries (Fig. 389).
The Right Coronary Artery (a. coronaria [cordis] dextra), about the size of a
crow's quill, arises from the anterior sinus of Valsalva. It passes forward between
the pulmonary artery and the right auricular appendix, then runs obliquely to the
right side, in the groove between the right auricle and ventricle, and, curving
around the right border of the heart, runs to the left along its posterior surface as
far as the posterior interventricular groove, where it divides into two branches, one
of which, the transverse, continues onward in the groove between the left auricle
and ventricle, and anastomoses with the left coronary; the other, the descending
(ramus descendens posterior a. coronariae [cordis] dextrae) , courses along the posterior
interventricular furrow, supplying branches to both ventricles and to the septum,
and anastomosing at the apex of the heart with the descending branches of the left
coronary. This vessel sends a large branch, the marginal, along the thin margin
of the right ventricle to the apex, which in its course gives off numerous small
branches to the anterior and posterior surfaces of the ventricle. It also gives off
THE ARCH OF THE AORTA
593
a branch, the infundibular, which ramifies over the front part of the conus arte-
riosus of the right ventricle.
The Left Coronary Artery (a. coronaria [cordis] sinistra), larger than the
former, arises from the left posterior sinus of Valsalva; it passes forward between
the pulmonary artery and the left auricular appendix, and divides into two
branches. Of these, one, the transverse, passes transversely outward in the left
auriculo-ventricular groove, and winds around the left border of the heart to its
posterior surface, where it anastomoses with the transverse branch of the right
coronary ; the other, the descending (ramus descendens anterior a. coronariae [cordis]
sinistrae), passes along the anterior interventricular groove to the apex of the heart,
where it anastomoses with the descending branches of the right coronary. The left
coronary supplies the left auricle and its appendix, gives branches to both ventri-
cles, and numerous small branches to the pulmonary artery and commencement
of the aorta.1
Peculiarities. — These vessels occasionally arise by a common trunk, or their number may
be increased to three, the additional branch being of small size. More rarely there are two
additional branches.
THE ARCH OF THE AORTA (ARCUS AORTAE).
The arch, or transverse aorta, commences at the upper border of the second
chondro-sternal articulation of the right side, and passes at first upward and back-
ward and from right to left, and then from before backward, to the left side of the
lower border of the fourth thoracic vertebra behind. Its upper border is usually
about an inch below the upper margin of the sternum.
VENA AZYGOS MAJOR
THORACIC DUCT
TRACHEA
JUST ABOVE DIVISI
PRECAVA
RIGHT PLEURA
ASCENDING
PORTION OF Al
VAGUS NERVE
DESCENDING
PORTION OF ARCH.
LEFT PLEURA
PHRENIC NERVE
FIG. 392.— Horizontal section through the fourth thoracic vertebra — upper surface of the lower segment.
The cut is made at the lower part of the transverse portion of the aortic arch.
Between the origin of the left subclavian artery and the attachment of the
ductus arteriosus the lumen of the foetal aorta is considerably narrowed, forming
what is termed the aortic isthmus (isthmus aortae) , while immediately beyond the
ductus arteriosus the vessel presents a fusiform dilatation which His has named
the aortic spindle (aortenspindel) — the point of junction of the two parts being
marked in the concavity of the arch by an indentation or angle. These con-
ditions persist, to some extent, in the adult, where His found that the average
diameter of the spindle exceeded that of the isthmus by 3 mm. (about one-eighth
of an inch).
1 According to Dr. Samuel West, there is a very free and complete anastomosis between the two coronary
arteries (Lancet, June 2, 1883, p. 945). This, however, is not the view generally held by anatomists, for, with
the exception of the anastomosis mentioned above in the auriculo-ventricular and interventricular grooves, it
is believed that the two arteries only communicate by very small vessels in the substance of the heart. — ED. of
15th English edition.
38
594
THE BLOOD-VASCULAR SYSTEM
Relations. — Its anterior surface is covered by the pleurae and lungs (much
more by the left lung than by the right) and the remains of the thy m us gland,
and crossed toward the left side by the left vagus and phrenic nerves and
superficial cardiac branches of the left sympathetic and vagus, and by the left
superior intercostal vein. Its posterior surface lies on the trachea, just above its
bifurcation, on the great, or deep, cardiac plexus, the oesophagus, thoracic duct,
and left recurrent laryngeal nerve. Its upper border is in relation with the left
innominate vein, and from its upper part are given off the innominate, left com-
mon carotid and left subclavian arteries. Its lower border is in relation with the
bifurcation of the pulmonary artery, the remains of the ductus arteriosus, which
is connected with the left division of that vessel, and the superficial cardiac plexus;
the left recurrent laryngeal nerve winds round it from before backward, whilst
the left bronchus passes below it.
PLAN OF THE RELATIONS OF THE ARCH OF THE AORTA.
Above.
Left innominate vein.
Innominate artery.
Left carotid.
Left subclavian.
In Front.
Pleurae and lungs.
Remains of thymus gland.
Left vagus nerve.
Left phrenic nerve.
Superficial cardiac nerves.
Left superior intercostal vein.
Behind.
Trachea.
Deep cardiac plexus.
(Esophagus.
Thoracic duct.
Left recurrent nerve.
Below.
Bifurcation of pulmonary artery.
Remains of ductus arteriosus.
Superficial cardiac plexus.
Left recurrent nerve.
Left bronchus.
Peculiarities. — The height to which the aorta rises in the chest is usually about an inch below
the upper border of the sternum ; but it may ascend nearly to the top of that bone. Occasionally
it is found an inch and a half, more rarely two or even three inches, below this point.
IN DIRECTION. — Sometimes in man, as is normal in birds, the aorta arches over the root of
the right instead of the left lung, and passes down on the right side of the spine. In such cases
all of the viscera of the thoracic and abdominal cavities are transposed. Less frequently, the
aorta, after arching over the root of the right lung, is directed to its usual position on the left
side of the spine, this peculiarity not being accompanied by any transposition of the viscera.
IN CONFORMATION. — The aorta occasionally divides, as in some quadrupeds, into an ascend-
ing and descending trunk, the former of which is directed vertically upward, and subdivides
into three branches, to supply the head and upper extremities. Sometimes the aorta subdivides
soon after its origin into two branches, which soon reunite. In one of these cases the oesophagus
and trachea were found to pass through the interval left by the division of the aorta; this is
the normal condition of the vessel in the reptilia.
Surgical Anatomy. — Of all the vessels of the arterial system, the aorta, and more especially
its arch, is most frequently the seat of disease; hence it is important to consider some of the
consequences that may ensue from aneurism of this part.
It will be remembered that the ascending aorta is continued in the pericardium, just behind
the sternum, being crossed at its commencement by the pulmonary artery and right auricular
appendix, and having the right pulmonary artery behind, the vena cava on the right side, and
the pulmonary artery and left auricle on the left side.
Aneurism of the ascending aorta, in the situation of the sinuses of Valsalva, in the great major-
ity of cases, affects the anterior sinus; this is mainly owing to the fact that the regurgitation
of blood upon the sinuses takes place chiefly on the anterior aspect of the vessel. As the aneuris-
mal sac enlarges it may compress any or all of the structures in immediate proximity to it,
but chiefly projects toward the right anterior side, and, consequently, interferes mainly with
those structures that have a corresponding relation with the vessel. In the majority of cases it
595
hursts into the cavity of the pericardium, the patient suddenly drops dead, and, upon a post-
mortem examination, the pericardial sac is found full of blood; or it may compress the right
auricle, or the pulmonary artery and adjoining part of the right ventricle, and open into one or
the other of these parts, or may press upon the precava.
Aneurism of the ascending aorta, originating above the sinuses, most frequently implicates
the right anterior wall of the vessel, where, as has been explained, there exists a normal dilata-
tion, the great sinus of the aorta; this is probably mainly owing to the blood being impelled
a<rainst this part. The direction of the aneurism is also chiefly toward the right of the median
line. It attains a large size and projects forward, it may absorb the sternum and the cartilages
of the ribs, usually on the right side, and appear as a pulsating tumor on the front of the chest,
just below the manubrium; or it may burst into the pericardium, or may compress or open into
the right lung, the trachea, bronchi, or oesophagus.
Right pulmonary
vein.
Right pulmonary
vein.
Vena azyg<
major
Left subclavian
artery.
Left common
carotid artery.
•Left innomi-
nate vein.
Inferior thyroid
vein.
^~
Right innomi-
nate vein.
Right subclavian artery. Right common carotid artery.
FIG. 393. — Relation of great vessels at base of heart, seen from above. (From a preparation in the Museum
of the Royal College of Surgeons of England.)
Regarding the transverse aorta, the student is reminded that the vessel lies on the trachea,
the oesophagus, and thoracic duct; that the recurrent laryngeal nerve winds around it; and that
from its upper part are given off three large trunks, which supply the head, neck, and upper
extremities. An aneurismal tumor, taking origin from the posterior part of the vessel, its most
usual site, may press upon the tracheji, impede the breathing, or produce cough, haemoptysis,
or stridulous breathing, or it may ultimately burst into that tube, producing fatal hemorrhage.
Again, its pressure on the laryngeal nerves may give rise to symptoms which so accurately
resemble those of laryngitis that the operation of tracheotomy has in some cases been resorted
to, from the supposition that disease existed in the larynx; or it may press upon the thoracic
duct and destroy life by inanition; or it may involve the oesophagus, producing dysphagia; or
may burst into the oesophagus, when fatal hemorrhage will occur. Again, the innominate
artery, or the subclavian, or left carotid, may be so obstructed by clots as to produce a weakness,
or even a disappearance, of the pulse in one or the other wrist or in the left temporal artery; or
the tumor may present itself at or above the manubrium, generally either in the median line
or to the right of the sternum, and may simulate an aneurism of one of the arteries of the neck.
Branches (Figs. 389 and 390). — The branches given off from the arch of the
aorta are three in number: the innominate, the left common carotid, and the left
subclavian arteries.
Peculiarities. POSITION OF THE BRANCHES. — The branches, instead of arising from the high-
est part of the arch (their usual position), may be moved more to the right, arising from the
commencement of the transverse or upper part of the ascending portion; or the distance from
one another at their origin may be increased or diminished, the most frequent change in this
respect being the approximation of the left carotid toward the innominate artery.
596 THE BLOOD-VASCULAR SYSTEM
The Number of the primary branches may be reduced to a single vessel, or more commonly
two: the left carotid arising from the innominate artery, or (more rarely) the carotid and sub-
clavian arteries of the left side arising from the innominate artery. But the number may be
increased to four, from the right carotid and subclavian arteries arising directly from the aorta,
the innominate being absent. In most of these latter cases the right subclavian has been found
to arise from the left end of the arch; in other cases it was the second or third branch given off
instead of the first. Another common form in which there are four primary branches is that
in which the left vertebral artery arises from the arch of the aorta between the left carotid and
subclavian arteries. Lastly, the number of trunks from the arch may be increased to five or
six; in these instances, the external and internal carotids arise separately from the arch, the
common carotid being absent on one or both sides. In some cases, where six branches have
been found, it has been due to a separate origin of the vertebral on both sides.
NUMBER AS USUAL, ARRANGEMENT DIFFERENT. — When the aorta arches over to the right
side, the three branches have an arrangement the reverse of what is usual, the innominate sup-
plying the left side, and the carotid and subclavian (which arise separately) the right side. In
other cases, where the aorta takes its usual course, the tv/o carotids may be joined in a common
trunk, and the subclavians arise separately from the arch, the right subclavian generally arising
from the left end of the arch.1
In some instances other arteries are found to arise from the arch of the aorta. Of these the
most common are the bronchial, one or both, and the thyroidea ima; but the internal mammary
and the inferior thyroid have been seen to arise from this vessel.
The Innominate Artery (A. Anonyma) (Figs. 389 and 390).
The innominate or brachio-cephalic artery is the largest branch given off
from the arch of the aorta. It arises, on a level with the upper border of
the second right costal cartilage, from the commencement of the arch of the
aorta in front of the left carotid, and, ascending obliquely to the upper border of
the right sterno-clavicular articulation, divides into the right common carotid and
right subclavian arteries. This vessel varies from an inch and a half to two inches
in length.
Relations. — In front, it is separated from the first piece of the sternum by the
Sterno-hyoid and Sterno-thyroid muscles, the remains of the thymus gland, the
left innominate and right inferior thyroid veins which cross its root, and some-
times the inferior cervical cardiac branch of the right vagus. Behind, it lies
upon the trachea, which it crosses obliquely, and continuing upward it lies in the
right pleura. On the right side is the right innominate vein, right vagus nerve,
and the pleura; and on the left side, the remains of the thymus gland, the origin
of the left carotid artery, the left inferior thyroid vein, and the trachea
Branches. — The innominate usually gives off no branches, but occasionally a
small branch, the thyroidea ima, is given off from this vessel. It also sometimes
gives off a thymic or bronchial branch.
The Thyroidea Ima (a. thyroidea ima), which is occasionally present, ascends in
front of the trachea to the lower part of the thyroid body, which it supplies. It
varies greatly in size, and appears to compensate for the deficiency or absence of
one of the other thyroid vessels. It occasionally is found to arise from the right
common carotid or from the aorta, the subclavian, or internal mammary vessels.
PLAN OF THE RELATIONS OF THE INNOMINATE ARTERY.
In front.
Sternum.
Sterno-hyoid and Sterno-thyroid muscles.
Remains of the thymus gland.
Left innominate and right inferior thyroid veins.
Inferior cervical cardiac branch from right vagus nerve. «
1 The anomalies of the aorta and its branches are minutely described by Krause in Henle's Anatomy (Bruns-
wick, 1868), vol. iii. p. 203 et se<j. — ED. of 15th English edition.
THE INNOMINATE ARTERY 597
Right side. f >. Left side.
Right innominate vein. / innominate ] Remains of thymus.
Right vagus nerve. I A**1?- \ Left carotid.
Pleura. \ / Left inferior thyroid vein.
^^_^^ Trachea.
Behind.
Trachea.
Right pleura.
Peculiarities in Point of Division. — When the bifurcation of the innominate artery varies
from the point above mentioned it sometimes ascends a considerable distance above the sternal
end of the clavicle; less frequently it divides below it. In the former class of cases its length
may exceed two inches, and in the latter be reduced to an inch or less. These are points of con-
siderable interest for the surgeon to remember in connection with the operation of tying this
vessel.
Position. — When the aorta arches over to the right side, the innominate is directed to the
left side of the neck instead of the right.
Collateral Circulation. — Allan Burns demonstrated, on the dead subject, the possibility of
the establishment of the collateral circulation after ligature of the innominate artery, by tying
and dividing that artery, after which, he says, "Even coarse injection, impelled into the aorta,
passing freely by the anastomosing branches into the arteries of the right arm, filling them and
all the vessels of the head completely."1 The branches by which this circulation would be car-
ried on are very numerous; thus, all the communications across the middle line between the
branches of the carotid arteries of opposite sides would be available for the supply of blood to
the right side of the head and neck; while the anastomosis between the superior intercostal of
the subclavian and the first aortic intercostal (see infra on the collateral circulation after oblitera-
tion of the thoracic aorta) would bring the blood, by a free and direct course, into the right
subclavian: the numerous connections, also, between the intercostal arteries and the branches
of the axillary and internal mammary arteries would, doubtless, assist in the supply of blood to
the right arm, while the deep epigastric, from the external iliac, would, by means of its anasto-
mosis with the internal mammary, compensate for any deficiency in the vascularity of the wall
of the chest.
Surgical Anatomy.— The innominate artery has been tied at least thirty times and in six
instances, according to Mr. Jacobson, the patient survived. Mott's patient, however, on
whom the operation was first performed, lived nearly four weeks, and Graefe's more than
two months. In 1895 Burrell, of Boston, resected the right sterno-clavicular articulation with
the upper end of the sternum and tied the innominate. The patient lived 104 days. The
ligation was first successfully performed by A. W. Smyth, of New Orleans, in 1864, for sub-
clavian aneurism. The patient died ten years later of the original aneurism, which was reformed
by the collaterals. The chief danger of the operation appears to be the frequency of secondary
hemorrhage; but in the present day, with the practice of aseptic surgery and our greater
knowledge of the use of the ligature, more favorable results may be anticipated. Other causes
of death after operation are pleurisy, pericarditis, and suppurative cellulitis. The main
obstacles to the operation are, as the student will perceive from his dissection of this vessel,
the deep situation of the artery behind and beneath the sternum, and the number of important
structures which surround it in every part.
In order to apply a ligature to this vessel, the patient is to be placed upon his back, with the
thorax slightly raised, the head bent a little backward, and the shoulder on the side of the aneu-
rism strongly depressed, so as to draw out the artery from behind the sternum into the neck.
An incision three or more inches long is then made along the anterior border of the Sterno-mas-
toid muscle, terminating at the sternal end of the clavicle. From this point a second incision is
carried about the same length along the upper border of the clavicle. The skin is then dissected
back, and the Platysma divided on a director: the sternal end of the Sterno-mastoid is now
brought into view, and, a director being passed beneath it and close to its under surface, so as to
avoid any small vessels, it is to be divided; in like manner the clavicular origin is to be divided
throughout the whole or greater part of its attachment. By pressing aside any loose cellular
tissue or vessels that may now appear the Sterno-hyoid and Sterno-thyroid muscles will be
exposed, and must be divided, a director being previously passed beneath them. The inferior
thyroid veins may come into view, and must be carefully drawn, either upward or downward, by
means of a blunt hook, or tied with double ligatures and divided. After tearing through a
strong fibro-cellular lamina, the right carotid is brought into view, and, being traced downward,
the arteria innominata is arrived at. The left innominate vein should now be depressed; the
1 Surgical Anatomy of the Head and Neck, p. 62.
598 THE BLOOD-VASCULAR SYSTEM
right innominate vein, the internal jugular vein, and the vagus nerve drawn to the right side;
and a curved aneurism needle may then be passed around the vessel, close to its surface,
and in a direction from below upward and inward, care being taken to avoid the right pleural
sac, the trachea, and cardiac nerves. The ligature should be applied to the artery as high as
possible, in order to allow room between it and the aorta for the formation of the coagulum.
The importance of avoiding the thyroid plexus of veins during the primary steps of the opera-
tion, and the pleural sac whilst including the vessel in the ligature, should be most carefully borne
in mind. After the artery has been secured, the common carotid should be tied about half an
inch above its origin, and also the thyroidea ima if the vessel is of any size. The several muscles
are united by buried sutures. An easier and safer plan than the above is that employed by
Burrell — viz., resection of the right sterno-clavicular articulation and of the upper end of the
.sternum.
ARTERIES OF THE HEAD AND NECK.
The chief artery which supplies the head and neck is the common carotid: it
ascends in the neck and divides into two branches: the External Carotid, supply-
ing the superficial parts of the head and face and the greater part of the neck;
and the Internal Carotid, supplying to a great extent the parts within the cranial
cavity.
THE COMMON CAROTID ARTERY (A. CAROTIS COMMUNIS) (Figs. 388, 389,
390, 394).
The common carotid arteries, Although occupying a nearly similar position in
the neck, differ in position, and, consequently, in their relation at their origin.
The right common carotid (a. carotis communis dextra) arises from the innom--
inate artery, behind the right sterno-clavicular articulation. The left common
carotid (a. carotis communis sinistra) arises from the highest part of the arch of
the aorta, and is, consequently, longer, and at its origin is contained within
the thorax. The course and relations of that portion of the left carotid which
intervenes between the arch of the aorta and the left sterno-clavicular articulation
will first be described. (See Figs. 388, 389, and 390.)
The left carotid within the thorax ascends obliquely outward from the arch of
the aorta to the root of the neck. In front, it is separated from the first piece
•of the sternum by the Sterno-hyoid and Sterno-thyroid muscles, the left innomi-
nate vein, and the remains of the thymus gland; behind, it lies on the trachea,
resophagus, thoracic duct, and the left recurrent laryngeal nerve. Internally, it
is in relation with the innominate artery, inferior thyroid veins, and remains of the
thymus gland; externally, with the left vagus nerve, left pleura, and left lung.
'The left subclavian artery is posterior and slightly external to it.
PLAN OF THE RELATIONS OF THE LEFT COMMON CAROTID.
THORACIC PORTION.
In front.
Sternum.
Sterno-hyoid and Sterno-thyroid muscles.
Left innominate vein.
Remains of the thymus gland.
Internally. / \ Externally.
I Left Common \
Innominate artery. / Carotid. i Left vagus nerve.
Inferior thyroid veins. I portion.0 / Left pleura and lung.
Remains of the thymus gland. V J Left subclavian artery.
Behind.
Trachea.
(Esophagus.
Thoracic duct.
Left recurrent laryngeal nerve.
THK COMMON CAROTID ARTERY
599
In the neck the two common carotids resemble each other so closely that one
description will apply to both. Each vessel passes obliquely upward from behind
the sterno-clavicular articulation to a level with the upper border of the thyroid
cartilage, opposite the fourth cervical vertebra, where it divides into the external
and internal carotid; these names being derived from the distribution of the arteries
to the external parts of the head and face and to the internal parts of the cranium
and orbit respectively.
FIG. 395.— Plan of the
branches of the external
carotid.
FIG. 394. — Surgical anatomy of the arteries of the neck, showing the carotid and subclavian arteries
At the lower part of the neck the two common carotid arteries are separated
from each other by a small interval, which contains the trachea; but at the upper
part, the thyroid body, the larynx and pharynx project forward between the
two vessels, and give the appearance of their being placed farther back in this
situation. The common carotid artery is contained in a sheath derived from the
600
THE BLOOD-VASCULAR SYSTEM
deep cervical fascia, which also encloses the internal jugular vein and vagus nerve,
the vein lying on the outer side of the artery, and the nerve between the artery
and vein, on a plane posterior to both. On opening the sheath these three struc-
tures are seen to be separated from one another, each being enclosed in a separate
fibrous investment.
Relations. — At the lower part of the neck the common carotid artery is very
deeply seated, being covered by the integument, superficial fascia, Platysma, and
deep cervical fascia, the Sterno-mastoid, Sterno-hyoid, an'd Sterno-thyroid muscles,
and by the Omo-hyoid, opposite the cricoid cartilage; but in the upper part of its
course, near its termination, it is more superficial, being covered merely by the
integument, the superficial fascia, Platysma, deep cervical fascia, and inner margin
of the Sterno-mastoid, and, when the latter is drawn backward, it is seen to be
contained in a triangular space, bounded behind by the Sterno-mastoid, above by
the posterior belly of the Digastric, and below by the anterior belly of the Omo-
hyoid. This part of the artery is crossed obliquely, from within outward, by the
sterno-mastoid artery; it is crossed also by the superior and middle thyroid veins,
which terminate in the internal jugular; and, descending on its-sheath in front, is
seen the descendens hypoglossi nerve, this filament being joined by one or two
branches from the cervical nerves, which cross the vessel from without inward.
Sometimes the descendens hypoglossi is contained within the sheath. The middle
thyroid vein crosses the artery about its middle, and the anterior jugular vein below;
the latter, however, is separated from the artery by the Sterno-hyoid and Sterno-
thyroid muscles. Behind, the artery is separated from the transverse processes of
the vertebrae by the Longus colli and Rectus capitis anticus major muscles, the
sympathetic nerve being interposed between it and the muscles. The recurrent
laryngeal nerve and inferior thyroid artery cross behind the vessel at its lower part.
Internally, it is in relation with the trachea and thyroid gland, the latter overlapping
it, the inferior thyroid artery and recurrent laryngeal nerve being interposed:
higher up, with the larynx and pharynx. On its outer side are placed the
internal jugular vein and vagus nerve. At the lower part of the neck the internal
jugular vein on the right side diverges from the artery, but on the left side it
approaches it, and often overlaps its lower part. This is an important fact to bear
in mind during the performance of any operation on the lower part of the left
common carotid artery. In this region the relation which the right and left recur-
rent laryngeal nerves bear to the arteries is not identical. The left recurrent laryn-
geal nerve lies behind the thoracic portion of the left common carotid artery and
internal to the cervical portion of the vessel. The right nerve passes obliquely
upward and inward behind the right common carotid to reach its inner side.
PLAN OF THE RELATIONS OF THE COMMON CAROTID ARTERY.
Integument and superficial fascia.
Deep cervical fascia.
Platysma.
Sterno-mastoid.
Sterno-hyoid.
Sterno-thyroid.
Externally.
Internal jugular vein.
Vagus nerve.
In front.
Omo-hyoid.
Descendens and Communicans hypoglossi
nerves.
Sterno-mastoid artery.
Superior and middle thyroid veins.
Anterior jugular vein.
Internally.
Trachea.
Thyroid gland.
Recurrent laryngeal nerve.
Inferior thyroid artery.
Larynx.
Pharynx.
THE COMMON CAROTID ARTERY 601
Behind.
Longus colli. Sympathetic nerve.
Rectus capitis anticus major. Inferior thyroid artery.
Recurrent laryngeal nerve.
Peculiarities as to Origin. — The right common carotid may arise above or below the upper
border of the sterno-clavicular articulation. This variation occurs in one out of about eight
cases and a half, and the origin is more frequently below than above; or the artery may arise
as a separate branch from the arch of the aorta or in conjunction with the left carotid. The
lc/f common carotid varies more frequently in its origin than the right. In the majority of abnor-
mal cases it arises with the innominate artery, or, if the innominate artery is absent, the two
carotids arise usually by a single trunk. It rarely joins with the left subclavian, except in cases
of transposition of the arch.
Peculiarities as to Point of Division.— The most important peculiarities of this vessel, in
a surgical point of view, relate to its place of division in the neck. In the majority of abnormal
cases this occurs higher than usual, the artery dividing into two branches opposite the hyoid
bone, or even higher; more rarely it occurs below, opposite the middle of the larynx or the lower
border of the cricoid cartilage; and one case is related by Morgagni where the common carotid,
only an inch and a half in length, divided at the root of the neck. Very rarely the common
carotid ascends in the neck without any subdivision, the internal carotid being wanting; and
in a few cases the common carotid has been found to be absent, the external and internal carotids
arising directly from the arch of the aorta. This peculiarity existed on both sides in some instances,
on one side in others.
Occasional Branches. — The common carotid usually gives off no branch previous to its
bifurcation; but it occasionally gives origin to the superior thyroid or its laryngeal branch, the
ascending pharyngeal, the inferior thyroid, or, more rarely, the vertebral artery.
Surface Marking. — The carotid arteries are covered throughout their entire extent by the
Sterno-mastoid muscle, but their course does not correspond to the anterior border of the muscle,
which passes in a somewhat curved direction from the mastoid process to the sterno-clavicular
joint. The course of the artery is indicated more exactly by a line drawn from the sternal end
of the clavicle below, to a point midway between the angle of the jaw and the mastoid process
above. That portion of the line below the level of the upper border of the thyroid cartilage
would represent the course of the vessel.
Surgical Anatomy. — The operation of tying the common carotid artery may be necessary
in a case of wound of that vessel or its branches, in aneurism, or in a case of pulsating tumor of
the orbit or skull. If the wound involves the trunk of the common carotid, it will be necessary
to tie the artery through the wound above and below the wounded part. If the wound is too small
to admit of safe and rapid work it must be enlarged. In cases of aneurism, or where one of
the branches of the common carotid is wounded in an inaccessible situation, it may be judged
necessary to tie the trunk. In such cases the whole of the artery is accessible, and any part may
be tied except close to either end. When the case is such as to allow of a choice being made,
the lower part of the carotid should never be selected as the spot upon which to place a ligature,
for not only is the artery in this situation placed very deeply in the neck, but it is covered by
three layers of muscles, and, on the left side, in the great majority of cases, the internal jugular
vein passes obliquely in front of it. Neither should the upper end be selected, for here the
superior thyroid vein and its tributaries would give rise to very considerable difficulty in the appli-
cation of a ligature. The point most favorable for the operation is that part of the vessel which
is at the level of the cricoid cartilage. It occasionally happens that the carotid artery bifurcates
below its usual position: if the artery be exposed at its point of bifurcation, both divisions of
the vessel should be tied near their origin, in preference to tying the trunk of the artery near its
termination; and if, in consequence of the entire absence of the common carotid or from its
early division, two arteries, the external and internal carotids, are met with, the ligature should
be placed on that vessel which is found on compression to be connected with the disease.
Ligation of the Carotid at the Level of the Cricoid Cartilage (Ligation in the Triangle of
Election). — The triangle of election is bounded posteriorly by the anterior edge of the sterno-
cleido-mastoid ; is bounded above by the posterior belly of the digastric; is bounded below by the
anterior belly of the omohyoid. In this operation the direction of the vessel and the inner
margin of the Sterno-mastoid are the chief guides to its performance. The patient should be
placed on his back with the head thrown back and turned slightly to the opposite side: an
incision is to be made, three inches long, in the direction of the anterior border of the Sterno-
mastoid, so that the centre corresponds to the level of the cricoid cartilage; after dividing the
integument, superficial fascia, and Platysma, the deep fascia must be cut through on a director,
so as to avoid wounding numerous small veins that are usually found beneath. The head
may now be brought forward so as to relax the parts somewhat, and the margins of the wound
are held asunder by retractors. The descendens hypoglossi nerve may now be exposed, and must
be avoided, and, the sheath of the vessel having been raised by forceps, is to be opened to a small
602 THE BLOOD- VASCULAR SYSTEM
extent over the artery at its inner side. The internal jugular vein may present itself alternately
distended and relaxed; this should be compressed both above and below, and drawn outward,
in order to facilitate the operation. The aneurism needle is passed from the outside, care
being taken to keep the needle in close contact with the artery, and thus avoid the risk of
injuring the internal jugular vein or including the vagus nerve. Before the ligature is tied it
should' be ascertained that nothing but the artery is included in it.
Ligation of the Common Carotid at the Lower Part of the Neck (Ligation in the Triangle
of Necessity}. — The triangle of necessity is bounded above by the anterior belly of the omo-
hyoid; is bounded behind by the anterior margin of the sterno-cleido-mastoid ; is bounded
in front by the mid-line of the neck. This operation is sometimes required in cases of
aneurism of the upper part of the carotid, especially if the sac is of large size. It is best
performed by dividing the sternal origin of the Sterno-mastoid muscle, but may be done
in some cases, if the aneurism is not of very large size, by an incision along the anterior
border of the Sterno-mastoid, extending down to the sterno-clavicular articulation, and by
then retracting the muscle. The easiest and best plan, however, is to make an incision two
or three inches long down the lower part of the anterior border of the Sterno-mastoid muscle
to the sterno-clavicular joint, and a second incision, starting from the termination of the first,
along the upper border of the clavicle for about two inches. This incision is made through the
superficial and deep fascia, and the sternal origin of the muscle is exposed. This is to be divided
on a director, and turned up, with the superficial structures, as a triangular flap. Some loose
connective tissue is to be divided or torn through, and the outer border of the Sterno-hyoid
muscle exposed. In doing this care must be taken not to wound the anterior jugular vein, which
crosses the muscle to reach the external jugular or subclavian vein. The Sterno-hyoid, and with
it the Sterno-thyroid, are to be drawn inward by means of a retractor, and the sheath of the
vessel is exposed. This must be opened with great care on its inner or tracheal side, so as to
avoid the internal jugular vein. This is especially necessary on the left side, where the artery
is commonly overlapped by the vein. On the right side there is usually an interval between the
artery and the vein, and not the same risk of wounding the latter.
The common carotid artery, being a long vessel without any branches, is particularly suitable
for the performance of Brasdor's operation for the cure of an aneurism of the lower part of the
vessel. Brasdor's procedure consists in ligaturing the artery on the distal side of the aneurism,
and in the case of the common carotid there are no branches given off from the vessel between
the aneurism and the site of the ligature; hence the flow of blood through the sac of the aneurism
is diminished and cure takes place in the usual way, by the deposit of laminated fibrin.
Collateral Circulation. — After ligature of the common carotid the collateral circulation
can be perfectly established, by the free communication which exists between the carotid arteries
of opposite sides, both without and within the cranium, and by enlargement of the branches of
the subclavian artery on the side corresponding to that on which the vessel has been tied — the
chief communication outside the skull taking place between the superior thyroid from the
external carotid and the inferior thyroid from the subclavian, the profunda cervicis from the
subclavian and the superior intercostal with the arteria princeps cervicis of the occipital;
the vertebral taking the place of the internal carotid within the cranium.
Sir A. Cooper had an opportunity of dissecting, thirteen years after the operation, the case
in which he first successfully tied the common carotid (the second case in which he performed
the operation).1 The injection, however, does not seem to have been a successful one. It showed
merely that the arteries at the base of the brain (circle of Willis) were much enlarged on the
side of the tied artery, and that the anastomosis between the branches of the external carotid on
the affected side and those of the same artery on the sound side was free, so that the external
carotid was pervious throughout.
The Intercarotid Body (carotid gland, retrocarotid corpuscle) (see the Ductless
Glands). <
The External Carotid Artery (A. Carotis Externa) (Figs. 392, 393, 394).
The external carotid artery commences opposite the upper border of the thyroid
cartilage, and, taking a slightly curved course, passes upward and forward, and
then inclines backward to the space between the neck of the condyle of the lower
jaw and the external meatus, where it divides into the superficial temporal and
internal maxillary arteries. It rapidly diminishes in size in its course up the
neck, owing to the number and large size of the branches given off from it. In
the child it is somewhat smaller than the internal carotid, but in the adult the
1 Guy's Hospital Reports, i., 56.
THE EXTERNAL CAROTID ARTERY
603
two vessels are of nearly equal size. At its commencement this artery is more
superficial, and placed nearer the middle line than the internal carotid, and is
contained in the triangular space bounded by the Sterno-mastoid behind, the
anterior belly of the Omo-hyoid below, and the posterior belly of the Digastric
and the Stylo-hyoid above.
Relations. — It is covered by the skin, superficial fascia, Platysma, deep fascia
and anterior margin of the Sterno-mastoid, and is crossed by the hypoglossal nerve,
and by the lingual and facial veins; it is afterward crossed by the Digastric and
Stylo-hyoid muscles, and higher up passes deeply into the substance of the parotid
gland, where it lies beneath the facial nerve and the junction of the temporal and
internal maxillary veins. Internally is the hyoid bone, wall of the pharynx, the
superior laryngeal nerve, arid the ramus of the jaw, from which it is separated by
a portion of the parotid gland. Externally, in the lower part of its course, is the
internal carotid artery. Behind it, near its origin, is the superior laryngeal nerve;
and higher up, it is separated from the internal carotid by the Stylo-glossus and
Stylo-pharyngeus muscles, the glosso-pharyngeal nerve, and part of the parotid
gland.
PLAN OF THE RELATIONS OF THE EXTERNAL CAROTID.
In front.
Skin, superficial fascia.
Platysma and deep fascia.
Anterior border of Sterno-mastoid.
Hypoglossal nerve.
Lingual and facial veins.
Digastric and Stylo-hyoid muscles.
Parotid gland with facial nerve and temporo-maxillary vein
in its substance.
Externally.
Internal carotid artery.
Internally.
Hyoid bone.
Pharynx.
Superior laryngeal nerve.
Parotid gland.
Ramus of jaw.
Behind.
Superior laryngeal nerve.
Stylo-glossus.
Stylo-pharyngeus.
Glosso-pharyngeal nerve.
Parotid gland.
Surface Marking. — The position of the external carotid artery may be marked out with
sufficient accuracy by a line drawn from the front of the m6atus of the external ear to the side
of the cricoid cartilage, slightly arching the line forward. •
Surgical Anatomy. — The application of a ligature to the external carotid may be required
in case of wounds of this vessel, or of its branches when these cannot be tied, and in some cases
of pulsating tumor of the scalp or face. The operation has not received the attention which it
deserves, owing to the fear which surgeons have entertained of secondary hemorrhage, on account
of the number of branches given off from the vessel. This fear, however, has been shown by
Mr. Cripps not to be well founded.1 Ligation is often very useful as a means of prevent-
ing excessive hemorrhage in operations about the face, jaws, and mouth. It is sometimes
employed with the hope of lessening the growth of tumors by cutting off the blood supply, but
ligation is useless for this purpose. Ligation of one external carotid artery arrests the circu-
lation for only a brief period, and within a very few days the circulation is practically freely
re-established. This result is seen to be inevitable when we recall the numerous branches of the
external carotid, their free anastomoses, and the fact that a very great number of extremely minute
vessels in the middle line join the external carotid system of one side to that of the other side.
Robert H. M. Dawbarn points out that ligation of both external carotids produces only temporary
anaemia, for "inside of a week or ten days thereafter the pulse can again be felt in the temporals and
facials upon both sides."2 Dawbarn points out that even after excision of the external carotids,
with separate ligation of each of the eight branches, blood can still reach the nose, tongue, etc.,
1 Med.-Chir Trans., Ixi., 229.
* The Treatment of Certain Malignant Growths.
604 THE BLOOD-VASCULAR SYSTEM
from outside systems by twenty-nine distinct routes. Whereas ligation of even both carotids will
not prevent the growth of a malignant tumor, excision of each external carotid, with separate
control of its eight branches, will sometimes prove of great value in retarding the progress of a
growth. It " starves " the growth and may cause it to shrink (Dawbarn's operation). To tie the
external carotid near its origin, below the point where it is crossed by the Digastric, an incision
about three inches in length should be made along the margin of the Sterno-mastoid, from the
angle of the jaw to the upper border of the thyroid cartilage. The ligature should be applied
between the lingual and superior thyroid branches. To tie the vessel above the Digastric,
between it and the parotid gland, an incision should be made, from the lobe of the ear to the
great cornu of the os hyoides, dividing successfully the skin, Platysma, and fascia. By drawing
the Sterno-mastoid outward, the posterior belly of the Digastric and Stylo-hyoid muscles down-
ward, and separating them from the parotid gland, the vessel will be exposed, and a ligature may
be applied to it. The circulation is at once re-established by the free communication between
most of the large branches of the artery (facial, lingual, superior thyroid, occipital) and the corre-
sponding arteries of the opposite side and by the anastomosis of its branches with those of the
internal carotid, and of the occipital with the branches of the subclavian, etc.
Branches. — The external carotid artery gives off eight branches, which, for
convenience of description, may be divided into four sets. (See Fig. 395, Plan of
the Branches.)
Anterior. Posterior. Ascending. Terminal.
Superior Thyroid. Occipital. Ascending Phar- Superficial Temporal.
Lingual. Posterior Auric- yngeal. Internal Maxillary.
Facial. ular.
The student is here reminded that many variations are met with in the number,
origin, and course of these branches in different subjects; but the above arrange-
ment is that which is found in the great majority of cases.
The Superior Thyroid Artery (a. thyreoidea superior] (Figs. 394, 395, and 398)
is the first branch given off from the external carotid, being derived from that vessel
just below the great cornu of the hyoid bone. At its commencement it is quite
superficial, being covered by the integument, fascia, and Platysma, and is contained
in the triangular space bounded by the Sterno-mastoid, Digastric, and Omo-hyoid
muscles. After running upward and inward for a short distance, it curves down-
ward and forward, in an arched and tortuous manner, to the upper part of the
thyroid gland, passing beneath the Omo-hyoid, Sterno-hyoid, and Sterno-thyroid
muscles, and supplying them. It distributes numerous branches to the upper part
of the gland, anastomosing with its fellow of the opposite side and with the
inferior thyroid arteries. The terminal branches supplying the gland are generally
two in number: one, the largest, the anterior branch (ramus anterior) , descends
at the anterior border of the lateral lobe of the gland, reaches the upper border
of the isthmus, and then passes in the substance of the isthmus to the middle
line of the neck, where it anastomoses with the corresponding artery of the
opposite side : the posterior branch (ramus posterior} descends along the posterior
border of the lateral lobe of the gland, the anterior and posterior branches
anastomose with each other and with branches of the inferior thyroid, and both
of them send branches to the thyroid gland (rami glandular es) . Besides the
arteries distributed to the muscles by which it is covered and to the substance
of the gland, the branches of the superior, thyroid are the following:
Hyoid. Superior Laryngeal.
Superficial Descending Branch (Sterno-mastoid). Crico-thyroid.
The Hyoid or Infra-hyoid (ramus hyoideus) is a small branch which runs along
the lower border of the os hyoides beneath the Thyro-hyoid muscle; after sup-
plying the muscles t connected to that bone, it forms an arch, by anastomosing
with the vessel of the opposite side.
THE EXTERNAL CAROTID ARTERY 605
The Superficial Descending or Sterno-mastoid Branch (ramus sternoclcidomas-
toideus] runs downward and outward across the sheath of the common carotid
artery, and supplies the Sterno-mastoid and neighboring muscles and integument.
There is frequently a separate branch from the external carotid distributed to the
Sterno-mastoid muscle.
The Superior Laryngeal (a. laryngea superior], larger than either of the preceding,
accompanies the internal laryngeal nerve, beneath the Thyro-hyoid muscle: it
pierces the thyro-hyoid membrane, and supplies the muscles, mucous membrane,
and glands of the larynx, anastomosing with the branch from the opposite
side.
The Crico-thyroid (ramus cricothyreoideus] is a small branch which runs trans-
versely across the crico-thyroid membrane, communicating with the artery of the
opposite side.
Arteries .of the Thyroid Gland. — The* thyroid gland is supplied by the two
superior thyroids from the external carotid ; the two inferior thyroids from the
subclavian, and sometimes also by the thyreoidea ima from the innominate.
The superior thyroid joins the gland at the summit of the upper horn, passes
down the posterior surface of the gland toward the inner surface of the upper horn,
comes forward to the anterior margin of the inner surface, descends to the isthmus,
and on the superior border of the isthmus anastomoses with the artery from the
other side. The superior thyroid artery sends numerous branches across the
anterior surface of the gland.
The inferior thyroid artery is larger than the superior artery. It passes to
the posterior surface of the gland and divides into branches. Some of the branches
enter the hilus ; others track across the posterior surface of the gland. The inferior
thyroid artery is close to the recurrent laryngeal nerve. The artery, as a rule,
passes behind the nerve before it divides into branches. It may divide first and
then one or two branches may be in front of the nerve. In unusual cases the
artery before division is in front of the nerve, or all the branches are in front.1
The thyreoidea ima passes to the lower portion of the gland. Berry points out
that the thyroid arteries communicate very freely with each other; only the small
branches pass into the interior of the gland; the larger branches "ramify on the
surface of the gland, just beneath the capsule."2
Surgical Anatomy. — The superior thyroid, or one 'of its branches, is often divided in cases
of cut throat, giving rise to considerable hemorrhage. In such cases the artery should be secured,
the wound 'being enlarged for that purpose, if necessary. The operation may be easily per-
formed, the position of the artery being very superficial, and the only structures of importance
covering it being a few small veins. The operation of tying the superior thyroid artery to lessen
the size of a bronchocele has been performed in numerous instances with partial or temporary
success. When, however, the collateral circulation between this vessel and the artery of the
opposite side, and the inferior thyroid, is completely re-established, the tumor usually regains
its former size, and hence the operation has been given ' up, especially as better results are
obtained by other means. Both thyroid arteries on the same side, and indeed all the four
thyroid arteries, have been tied in enlarged thyroid. The superior and inferior thyroid arteries
of the involved side are ligated before extirpating a goitrous lobe of the thyroid.
The position of the superficial descending branch is of importance in connection with the
operation of ligation of the common carotid artery. It crosses and lies on the sheath of this
vessel, and may chance to be wounded in opening the sheath. The position of the crico-thyroid
branch should be remembered, as it may prove the source of troublesome hemorrhage during
the operation of laryngotomy. In performing the operation of quick laryngotomy the crico-
thyroid membrane should be incised transversely in order to avoid this vessel.
The Lingual Artery (a. lingualis) (Figs. 394 and 395) arises from the external
carotid between the superior thyroid and facial; it first runs obliquely upward
and inwrard to the great cornu of the hyoid bone; it then curves downward and
forward, forming a loop which is crossed by the hypoglossal nerve, and, passing
1 Berry. Diseases of the Thyroid Gland. * Ibid.
006 THE BLOOD-VASCULAR SYSTEM
beneath the Digastric and Stylo-hyoid muscles, it runs horizontally forward,
beneath the Hyo-glossus, and finally, ascending almost perpendicularly to the
tongue, turns forward on Its under surface as far as the tip, under the name of
the ranine artery.
Relations. — Its first, or oblique, portion is superficial, being contained in the
same triangular space as the superior thyroid artery, resting upon the middle con-
strictor of the pharynx, and covered by the Platysma and fascia of the neck. Its
second, or curved, portion also lies upon the middle constrictor, being covered at
first by the tendon of the Digastric and the Stylo-hyoid muscle, and afterward by
the Hyo-glossus, the latter muscle separating it from the hypoglossal nerve. Its
third, or horizontal, portion lies between the Hyo-glossus and Genio-hyo-glossus
muscles. The fourth, or terminal, part, under the name of the ranine, runs along
the under surface of the tongue to its tip: it is very superficial, being covered
only by the mucous membrane, and rests on the Lingualis on the outer side of
the Genio-hyo-glossus. The hypoglossal nerve crosses the lingual artery, and then
becomes separated from it, in the second part of its course, by the Hyo-glossus
muscle.
Branches. — The branches of the lingual artery are — the
Hyoid. Sublingual.
Dorsalis Linguae. Ranine.
The Hyoid or Supra-hyoid Branch (ramus hyoideus) runs along the upper border
of the hyoid bone, supplying the muscles attached to it and anastomosing with
.its fellow of the opposite side.
The Dorsalis Linguae (ramus dorsalis linguae] (Fig. 445) arises from the lingual
artery beneath the Hyo-glossus muscle (which, in the figure, has been partly cut
away, to show the vessel) ; it ascends to the dorsum of the tongue, and supplies the
mucous membrane, the tonsil, soft palate, and epiglottis, anastomosing with its
fellow from the opposite side. This artery is frequently represented by two or
three small branches.
The Sublingual (a. sublingualis) , which may be described as a branch of bifur-
cation of the lingual artery, arises at the anterior margin of the Hyo-glossus muscle,
and runs forward between the Genio-hyo-glossus and the sublingual gland. It
supplies the substance of the gland, giving branches to the Mylo-hyoid and
neighboring muscles, the mucous membrane of the mouth and gums. One
branch runs behind the alveolar process of the lower jaw in the substance of the
gum to anastomose with a similar artery from the other side.
The Ranine or Deep Lingual (a. profunda linguae) may be regarded as the other
branch of bifurcation. It is usually described as the continuatidn of the lingual
artery; it runs along the under surface of the tongue, resting on the Inferior
lingualis, and covered by the mucous membrane of the mouth; it lies on the outer
side of the Genio-hyo-glossus, accompanied by the lingual nerve. On arriving
at the tip of the tongue it is said to anastomose with the artery of the opposite
side, but this is denied by Hyrtl. These vessels in the mouth are placed one on
each side of the frsenum.
Surgical Anatomy. — The lingual artery may be divided near its origin in cases of cut throat,
a complication that not unfrequently happens in this class of wounds; or severe hemorrhage
which cannot be restrained by ordinary means may ensue from a wound or deep ulcer of the
tongue. In the former case the primary wound may be enlarged if necessary, and the bleeding
vessels secured. In the latter case it has been suggested that the lingual artery should be tied
near its origin. Ligature of the lingual artery is also occasionally practised, as a palliative measure,
in cases of cancer of the tongue, in order to check the progress of the disease by starving the
growth, and it is sometimes tied as a preliminary measure to removal of the tongue. The operation
is a somewhat difficult one, on account of the depth of the artery, the number of important
structures by which it is surrounded, the loose and yielding nature of the parts upon which it is
supported, and its occasional irregularity of origin. An incision is to be made in a curved direc-
THE EXTERNAL CAROTID ARTERY
eo?
tion from ;i point one finder's breadth external to the symphysis of the jaw downward to the
cornu of the hyoid bone, and then upward to near the angle of the jaw. Care must be taken not
to carry this ineision too far backward, for fear of endangering the facial vein. In the first
incision the skin, superficial fascia, and Platysma will be divided, and the deep fascia exposed.
The deep fascia is then to be incised and the submaxillary gland exposed and pulled upward by
ret factors. A triangular space is now exposed, Lesser s triangle, bounded internally by the pos-
terior border of the Mylo-hyoid muscle: below and externally, by the tendon of the Digastric;
and above, by the hypoglossal nerve. The floor of the space is formed by the Hyo-glossus muscle,
beneath which the artery lies. The fibres of this muscle are now to be cut through horizontally
and the vessel exposed, care being taken, while near the vessel, not to open the pharynx.
Troublesome hemorrhage may occur in the division of the frcenum in children if the ranine
arteries, which lie on each side of it, are wounded. The student should remember that the opera-
tion is always to be performed with a pair of blunt-pointed scissors, and the mucous membrane
only is to be divided by a very superficial cut, which cannot endanger any vessel. The scissors,
also, should be directed away from the tongue. Any further liberation of the tongue which may
be necessary can be effected by tearing.
The Facial or External Maxillary Artery (a. maxillaris externa) (Figs. 394,
395, 396, and 397) arises a little above the lingual, and passes obliquely upward,
beneath the Digastric and Stylo-hyoid muscles, and frequently beneath the hypo-
glossal nerve; it now runs forward under cover of the body of the lower jaw, lodged
in a groove on the posterior surface of the submaxillary gland ; this may be called
the cervical part of the artery. It then curves upward over the body of the jaw
at the anterior inferior angle of the Masseter muscle; passes forward and upward
across the cheek to the angle of the mouth, then upward along the side of the nose,
ria septi nasi.
erior coronary.
Inferior coronary.
Inferior labial.
FIG. 396. — The arteries of the face and scalp.1
1 The muscular tissue of the lips must be supposed to have been cut away, in order to show the courae of the
coronary arteries
608 THE BLOOD- VASCULAR SYSTEM
and terminates at the inner canthus of the eye, under the name of the angular artery.
The facial artery, both in the neck and on the face, is remarkably tortuous : in
the former situation its tortuosity enables it to accommodate itself to the move-
ments of the pharynx in deglutition, and in the latter to the movements of the jaw
and the lips and cheeks.
Relations. — In the neck its origin is superficial, being covered by the integu-
ment, Platysma, and fascia; it then passes beneath the Digastric and Stylo-hyoid
muscles and part of the submaxillary gland. It lies upon the middle constrictor
of the pharynx, and is separated from the Stylo-glossus and Hyo-glossus muscles
by a portion of the submaxillary gland. On the face, where it passes over the
body of the lower jaw, it is comparatively superficial, lying immediately beneath
the Platysma. In this situation its pulsation may be distinctly felt, and compres-
sion of the vessel against the bone can be effectually made. In its course over the
face it is covered by the integument, the fat of the cheek, and, near the angle of the
mouth, by the Platysma, Risorius, and Zygomatic muscles. It rests on the Bucci-
nator, the Levator anguli oris, and the Levator labii superioris (sometimes piercing
or else passing under this last muscle). The facial vein lies to the outer side of
the artery, and takes a more direct course across the face, where it is separated
from the artery by a considerable interval. In the neck it lies superficial to the
artery. The branches of the facial nerve cross the artery, and branches of the
infraorbital nerve lie beneath it.
Branches. — The branches of this vessel may be divided into two sets: those
given off below the jaw (cervical), and those on the face (facial).
Cervical Branches. Facial Branches.
Inferior or Ascending Palatine. Muscular.
Tonsillar. Inferior Labial.
Submaxillary. Inferior Coronary.
Submental. Superior Coronary.
Muscular. Lateral Nasal.
Angular.
The Inferior or Ascending Palatine (a. palatine ascendens) passes up between
the Stylo-glossus and Stylo-pharyngeus to the outer side of the pharynx, along
which it is continued between the Superior constrictor and the Internal ptery-
goid to near the base of the skull. It supplies the neighboring muscles, the
tonsil, and Eustachian tube, and divides, near the Levator palati, into two
branches: one follows the course of the Levator palati, and, winding over the
upper border of the Superior constrictor, supplies the soft palate and the palatine
glands, anastomosing with its fellow of the opposite side and with the posterior
palatine branch of the internal maxillary artery; the other pierces the Superior
constrictor and supplies the tonsil, anastomosing with the tonsillar and ascending
pharyngeal arteries.
The Tonsillar (ramus tonsillaris) passes up between the Internal pterygoid
and Stylo-glossus, and then ascends along the side of the pharynx, perforating
the Superior constrictor, to ramify in the substance of the tonsil and root of the
tongue.
The Submaxillary or Glandular Branches (rami glandulares] consist of three 01
four large vessels, which supply the submaxillary gland, some being prolonged to
the neighboring muscles, lymphatic glands, and integument.
The Submental (a. submentalis) (Fig. 394), the largest of the cervical branches,
is given off from the facial artery just as that vessel quits the submaxillary gland:
it runs forward upon the Mylo-hyoid muscle, just below the body of the jaw and
beneath the Digastric; after supplying the surrounding muscles, and anastomosing
THE EXTERNAL CAROTID ARTERY 609
with the sublingual artery by branches which perforate the mylo-hyoid muscle, it
arrives at the symphysis of the chin, where it turns over the border of the jaw and
divides into a superficial and a deep branch; the former passes between the integu-
ment and Depressor labii inferioris, supplies both, and anastomoses with the
inferior labial. The deep branch passes between the latter muscle and the bone,
supplies the lip, and anastomoses with the inferior labial and mental arteries.
The Muscular Branches are distributed to the Internal pterygoid and Stylo-
hyoid in the neck, and to the Masseter and Buccinator on the face.
The Inferior Labial (a. labialis inferior) (Fig. 396) passes beneath the Depressor
anguli oris, to supply the muscles and integument of the chin and lower lip, anas-
tomosing with the inferior coronary and submental branches of the facial, and with
the mental branch of the inferior dental artery.
The Inferior Coronary (Figs. 396 and 397) is derived from the facial artery, near
the angle of the mouth : it passes upward and inward beneath the depressor anguli
oris, and, penetrating the Orbicularis oris muscle, runs in a tortuous course along
the edge of the lower lip between this muscle and the mucous membrane, inoscu-
lating with the artery of the opposite side. This artery supplies the labial glands,
the mucous membrane, and muscles of the lower lip, and anastomoses with the
inferior labial from the facial and the mental branch of the inferior dental artery.
FIG. 397. — The coronary arteries, the glands of the lips, and the nerves of the right side seen from the
posterior surface after removal of the mucous membrane. (Poirier and Charpy.)
The Superior Coronary (a. labialis superior) (Figs. 396 and 397) is larger and more
tortuous in its course than the preceding. It follows the same course along, the
edge of the upper lip, lying between the mucous membrane and the Orbicularis
oris, and anastomoses with the artery of the opposite side. It supplies the textures
of the upper lip, and gives off in its course two or three vessels which ascend to the
nose. One, named the inferior artery of the septum, ramifies on the septum of the
nostrils as far as the point of the nose, and there anastomoses with the naso-
palatine artery; another, the artery of the ala, supplies the ala of the nose.
The Lateralis Nasi is derived from the facial, as that vessel is ascending along
the side of the nose; it supplies the ala and dorsum of the nose, anastomosing
with its fellow, the nasal branch of the ophthalmic, the inferior artery of the sep-
tum, the artery of the ala, and the infraorbital.
The Angular Artery (a. angularis) is the termination of the trunk of the facial;
it ascends to the inner angle of the orbit, embedded in the fibres of the Levator
labii superioris alseque nasi, and accompanied by a large vein, the angular vein;
it distributes some branches on the cheek which anastomose with the infraorbital.
After supplying the lachrymal sac and Orbicularis palpebrarum muscle, the
angular artery terminates by anastomosing with the nasal branch of the oph-
thalmic artery.
The anastomoses of the facial artery are very numerous, not only with the
39
610
THE BLOOD- VASCULAR SYSTEM
vessel of the opposite side, but, in the neck, with the sublingual branch of the
lingual; with the ascending pharyngeal; and with the posterior palatine, a branch of
the internal maxillary, by its inferior or ascending palatine and tonsillar branches;
on the face, with the mental branch of the inferior dental as it emerges from the
mental foramen, with the transverse facial, a branch of the temporal; with the
infraorbital, a branch of the internal maxillary, and with the nasal branch of
the ophthalmic.
Peculiarities. — The facial artery not unfrequently arises by a common trunk with the lingual.
This vessel is also subject to some variations in its size and in the extent to which it supplies
the face. It occasionally terminates as the submental, and not unfrequently supplies the face
only as high as the angle of the mouth or nose. The deficiency is then supplied by enlargement
of one of the neighboring arteries.
Surgical Anatomy. — The passage of the facial artery over the body of the jaw would appear
to afford a favorable position for the application of pressure in case of hemorrhage from the
lips, the result either of an accidental wound or during an operation; but its application is useless,
except for a very short time, on account of the free communication of this vessel with its fellow
and with numerous branches from different sources. In a wound involving the lip it is better
to seize the part between the fingers, and evert it, when the bleeding vessel may be at once secured
with pressure-forceps. In order to prevent hemorrhage in cases of removal of diseased growths
from the part, the lip should be compressed on each side between the fingers and thumb or by
a pair of specially devised clamp-forceps, whilst the surgeon excises the diseased part. In order
to stop hemorrhage where the lip has been divided in an operation, it is necessary, in uniting
the edges of the wound, to pass the sutures through the cut edges from the skin almost as deep
as the mucous surface; by these means not only are the cut surfaces more neatly and securely
adapted to each other, but the possibility of hemorrhage is prevented by including in the suture
the divided artery. If the suture is, on the contrary, passed
through merely the cutaneous portion of the wound, hemor-
rhage occurs into the cavity of the mouth. The student
should, lastly, observe the relation of the angular artery to
the lachrymal sac, and it will be seen that, as the vessel
passes up along the inner margin of the orbit, it ascends on
its nasal side. In operating for fistula lacrimalis the sac
should always be opened on its outer side, in order that this
vessel may be avoided.
The Occipital Artery (a. occipitalis) (Figs. 394,
395, 396, and 398) arises from the posterior part of
the external carotid, opposite the facial, near the
lower margin of the Digastric muscle. At its origin
it is covered by the posterior belly of the Digastric
muscle and the Stylo-hyoid muscle, and the hypo-
glossal nerve winds around it from behind forward ;
higher up, it passes across the internal carotid artery,
the internal jugular vein, and the vagus and accessory
nerves; it then ascends to the interval between the
transverse process of the atlas and the mastoid pro-
cess of the temporal bone, and passes horizontally
backward, grooving the surface of the latter bone,
being covered by the Sterno-mastoid, Splenius,
Trachelo-mastoid, and Digastric muscles, and rest-
ing upon the Rectus lateralis, the Superior oblique,
and Complexus muscles ; it then changes its course
and passes vertically upward, pierces the fascia which connects the cranial attach-
ment of the Trapezius with the Sterno-mastoid, and ascends in a tortuous course
over the occiput, as high as the vertex, where it divides into numerous branches.
It is accompanied in the latter part of its course by the great occipital nerve, and
occasionally by a cutaneous filament from the suboccipital nerve.
DESCENDING
BRANCH OF
HYPOGLOSSAL
NERVE
FIG. 398. — The loop of the hypo-
glossal nerve and the branches of the
external carotid artery.
611
Branches. — The branches given off from this vessel are —
Muscular. Dural or Meningeal.
Sterno-mastoid. Mastoid.
Auricular. Arteria Princeps Cervicis.
The Muscular Branches (rami musculares) supply the Digastric, Stylo-hyoid,
Splenius, and Trachelo-mastoid muscles.
The Sterno-mastoid (a. sternocleidomastoided) is a large and constant branch,
generally arising from the artery close to its commencement, but sometimes
springing directly from the external carotid. It first passes downward and back-
ward over the hypoglossal nerve, and enters the substance of the muscle in com-
pany with the accessory nerve.
The Auricular Branch (ramus auricularis] supplies the back part of the concha*
It frequently gives off a branch, which enters the skull through the mastoid
foramen and supplies the dura, the diploe, and the mastoid cells.
The Dural or Meningeal Branch (ramus meningeus] ascends with the internal
jugular vein, and enters the skull through the foramen lacerum posterius, or
through the anterior condyloid foramen, to supply the dura in the posterior fossa.
The Mastoid Branch (ramus mastoideus) is a small vessel, by no means constant.
It passes into the skull through the mastoid foramen and is distributed upon the
dura of the posterior fossa.
The Arteria Princeps Cervicis (ramus descendens), the largest branch of the
occipital, descends along the back part of the neck and divides into a super-
ficial and a deep portion. The former runs beneath the Splenius, giving off
branches which perforate that muscle to supply the Trapezius, which anastomose
with the superficial cervical artery, a branch of the Transversalis colli : the latter
passes beneath the Complexus between it and the Semispinalis colli, and anasto-
moses with branches from the vertebral and with the deep cervical artery, a
branch of either the superior intercostal or the subclavian. The anastomosis
between these vessels serves mainly to establish the collateral circulation after
ligation of the carotid or subclavian artery.
The cranial branches (rami occipitales) of the occipital artery are distributed
upon the occiput; they are very tortuous, and lie between the integument and
Occipito-frontalis, anastomosing with the artery of the opposite side, the pos-
terior auricular and temporal arteries. They supply the back part of the
Occipito-frontalis muscle, the integument, and pericranium.
The Posterior Auricular Artery (a. auricularis posterior} (Figs. 394, 395, and
396) is a small vessel which arises from the external carotid, above the Digastric
and Stylo-hyoid muscles, opposite the apex of the styloid process. It ascends,
under cover of the parotid gland, on the styloid process of the temporal bone, to
the groove between the cartilage of the ear and the mastoid process, immediately
above which it divides into its two terminal branches, the auricular and mastoid.
Just before arriving at the mastoid process, this artery is crossed by the facial
nerve, and has beneath it the accessory nerve.
Branches. — Besides several small branches to the Digastric, Stylo-hyoid, and
Sterno-mastoid muscles and to the parotid gland, this vessel gives off three
branches :
Stylo-mastoid. Auricular. Mastoid.
The Stylo-mastoid Branch (a. stylomastoidea) enters the stylo-mastoid foramen,
and supplies the tympanum, mastoid cells, and semicircular canals. In the
young subject a branch from this vessel forms, with the tympanic branch from
the internal maxillary, a vascular circle, which surrounds the membrana tympani,
and from which delicate vessels ramify on that membrane. It anastomoses with
612 THE BLOOD-VASCULAR SYSTEM
the petrosal branch of the medidural artery by a twig, which enters the hiatus
Fallopii.
The Auricular Branch (ramus auricularis), one of the terminal branches, ascends
behind the ear, beneath the Retrahens auriculam muscle, and is distributed to
the back part of the cartilage of the ear, upon which it ramifies minutely, some
branches curving round the margin of the fibro-cartilage, others perforating it,
to supply its anterior surface. It anastomoses with the posterior branch of the
superficial temporal and also with the anterior auricular branches.
The Mastoid Branch (ramus mastoideus) passes backward, over the Sterno-
mastoid muscle, to the scalp above and behind the ear. It supplies the posterior
belly of the Occipito-frontalis muscles and the scalp in this situation. It anasto-
moses with the occipital artery.
The Ascending Pharyngeal Artery (a. pharyngea ascendens] (Figs. 394 and
395), the smallest branch of the external carotid, is a long, slender vessel, deeply
seated in the neck, beneath the other branches of the external carotid and the
Stylopharyngeus muscle. It arises from the back part of the external carotid, near
the commencement of that vessel, and ascends vertically between the internal
carotid and the side of the pharynx, to the under surface of the base of the skull,
lying on the Rectus capitis anticus major muscle.
Branches. — Its branches may be subdivided into four sets:
Prevertebral. Pharyngeal. Tympanic. Dural or Meningeal.
The Prevertebral Branches are numerous small vessels which supply the Recti
capitis antici and Longus colli muscles, the sympathetic, hypoglossal, and vagus
nerves, and the lymphatic glands. They anastomose with the ascending cervical
artery.
The Pharyngeal Branches (rami pharyngei) are three or four in number. Two
of these descend to supply the middle and inferior Constrictors and the Stylo-
pharyngeus, ramifying in the substance of the muscles and in the submucous
tissue of the mucous membrane lining them. The largest of the pharyngeal
branches passes inward, running upon the Superior constrictor, and sends rami-
fications to the soft palate and tonsil, which take the place of the ascending
palatine branch of the facial artery when that vessel is of small size. A twig
from this branch supplies the Eustachian tube.
The Tympanic Branch (a. tympanica inferior) is a small artery which passes
through a minute foramen in the petrous portion of the temporal bone, in com-
pany with the tympanic branch of the Glosso-pharyngeal nerve to supply the
inner wall of the tympanum and anastomose with the other tympanic arteries.
The Dural or Meningeal Branches consist of several small vessels, which pass
through foramina in the base of the skull, to supply the dura. One, the postdural
or posterior meningeal (a. meningea posterior), enters the cranium through the
foramen lacerumposterius; a second passes through the foramen lacerum medium;
and occasionally a third through the anterior condyloid foramen. They are all
distributed to the dura.
Surgical Anatomy. — The ascending pharyngeal artery has been wounded from the throat,
as in the case in which the stem of a tobacco-pipe was driven into the vessel, causing fatal hemor-
rhage. After removal of the tonsil there is sometimes severe bleeding. This is almost never
due to wounding of the internal carotid artery, as the latter vessel, if normally placed, is too
far away to be damaged. The bleeding comes from branches of the ascending pharyngeal,
tonsillar, or ascending palatine arteries.
The Superficial Temporal Artery (a. temporalis superficialis) (Fig. 394, 395, and
396), the smaller of the two terminal branches of the external carotid, appears, from
its direction, to be the continuation of that vessel. It commences in the substance
of the parotid gland, in the interspace between the neck of the lower jaw and the
THE EXTERNAL CAROTID ARTERY 613
external auditory meatus, crosses over the posterior root of the zygoma, passes
beneath the Attrahens auriculam muscle, lying on the temporal fascia, and
divides, about two inches above the zygomatic arch, into two branches, an anterior
and a posterior. This vessel is accompanied by the auriculo-temporal nerve.
The Anterior Temporal runs tortuously upward and forward to the forehead,
supplying the muscles, integument, and pericranium in this region, and anasto-
moses with the supra-orbital and frontal arteries. The terminal portion of the
anterior branch is called the frontal artery (ramus frontalis) .
The Posterior Temporal, larger than the anterior, curves upward and backward
along the side of the head, lying superficial to the temporal fascia, and inosculates
with its fellow of the opposite side, and with the posterior auricular and occipital
arteries. The terminal portion of the posterior branch is named the parietal
artery (ramus parietalis).
The superficial temporal artery, as it crosses the zygoma, is covered by the
Attrahens auriculam muscle, and by a dense fascia given off from the parotid
gland: it is crossed by the tempo ro-facial division of the facial nerve and one or
two veins, and is accompanied by the auriculo-temporal nerve, which lies behind
it. Besides some twigs to the parotid gland, the articulation of the jaw, and the
Masseter muscle.
Branches. — The branches of the superficial temporal artery are the —
Transverse Facial. Orbital.
Middle Temporal. Anterior Auricular.
The Transverse Facial Branch (a. transversa faciei) is given off from the tem-
poral before that vessel quits the parotid gland; running forward through its
substance, it passes transversely across the face, between Stenson's duct and
the lower border of the zygoma, and divides on the side of the face into numerous
branches, which supply the parotid gland, the Masseter muscle, and the integu-
ment, anastomosing with the facial, masseteric, and infra-orbital arteries. This
vessel rests on the Masseter, and is accompanied by one or two branches of the
facial nerve. It is sometimes a branch of the external carotid.
The Middle Temporal Artery (a. temporalis media) arises immediately above
the zygomatic arch, and, perforating the temporal fascia, gives branches to the
Temporal muscle, anastomosing with the deep temporal branches of the internal
maxillary. It occasionally gives off an orbital branch, which runs along the upper
border of the zygoma, between the two layers of the temporal fascia, to the outer
angle of the orbit. This branch, which may arise directly from the superficial
temporal artery, supplies the Orbicularis palpebrarum, and anastomoses with
the lachrymal and palpebral branches of the ophthalmic artery.
The Orbital Artery (a. zygomaticoorbitalis) comes off from the temporal just
above the zygoma and is distributed to the upper orbital margin.
The Anterior Auricular Branches (rami auriculares anteriores) are distributed
to the anterior portion of the pinna, the lobule, and part of the external meatus,
anastomosing with branches of the posterior auricular.
Surgical Anatomy. — Formerly the operation of arteriotomy was performed upon this vessel
in cases of inflammation of the eye or brain, but at the present time the operation is obsolete.
If the student will consider the relations of the trunk of the vessels as it crosses the zygomatic
arch, with the surrounding structures, he will observe that it is covered by a thick and dense
fascia, crossed by one of the main divisions of the facial nerve and one or two veins, and accom-
panied by the auriculo-temporal nerve. 'The anterior branch, on the contrary, is subcutaneous,
and is a large vessel.
The Internal Maxillary Artery (a. maxillaris internet) (Figs. 399 and 400), the
larger of the two terminal branches of the external carotid, arises from that vessel
opposite the neck of the condyle of the lower jaw, and is at first imbedded in the
614
THE BLOOD-VASCULAR SYSTEM
substance of the parotid gland ; it passes inward between the ramus of the jaw
and the internal lateral ligament, and then upon the outer surface of the External
pterygoid muscle to 'the spheno-maxillary fossa, to supply the deep structures
of the face. For convenience of description it is divided into three portions : a
maxillary, a pterygoid, and spheno-maxillary.
In the first part of its course, the maxillary portion, the artery passes horizontally
forward and inward, between the ramus of the jaw and the internal lateral liga-
ment. The artery here lies parallel to and a little below the auriculo-temporal
nerve; it crosses the inferior dental nerve, and lies along the lower border of the
External pterygoid muscle.
Ant. Temporal A.
Post. Temporal A.
FIG. 399. — The internal maxillary artery and its branches.
Pterjfffo-palati,
Parvidu
Small M<n
JUedidural
Middle Mem
Tympanic
FIG. 400.— Plan of the branches.
In the second part of its course, the pterygoid portion, it runs obliquely forward,
and upward upon the outer surface of the External pterygoid muscle, being
covered by the ramus of the lower jaw and lower part of the Temporal muscle;
or it may pass on the inner surface of the External pterygoid muscle to reach the
interval between its two heads, between which it passes to reach the spheno-
maxillary fossa.
In the third part of its course, the spheno-maxillary portion, it approaches the
superior maxillary bone, and enters the spheno-maxillary fossa in the interval
between the two heads of the External pterygoid muscle, where it lies in relation
with Meckel's ganglion, and gives off its terminal branches.
The branches of this vessel may be divided into three groups, corresponding
with its three divisions.
THE EXTERNAL CAROTID ARTERY 615
Branches of the First or Maxillary Portion (Fig. 400) :
Anterior Tympanic. Parvidural or Small Meningeal.
Deep Auricular. Inferior Dental.
Medidural or Middle Meningeal.
The Anterior Tympanic Branch (a. tympanica anterior] passes upward behind
the articulation of the lower jaw, enters the tympanum through the Glaserian
fissure, and ramifies upon the membrana tympani, forming a vascular circle
around the membrane with the stylo-mastoid artery, and anastomosing with
the Vidian and the tympanic branch from the internal carotid.
The Deep Auricular Branch (a. auricidaris profunda) often arises in common
with the preceding. It passes upward in the substance of the parotid gland,
behind the temporo-maxillary articulation, pierces the cartilaginous or bony wall
of the external auditory meatus, and supplies its cuticular lining and the outer
surface of the membrana tympani.
The Medidural or Middle Meningeal Branch (a. mediduralis, a. meningea media) is
the largest of the branches which supply the dura. It arises from the internal max-
illary, between the internal lateral ligament and the neck of the jaw, and passes
vertically upward between the two roots of the auriculo-temporal nerve to the fora-
men spinosum of the sphenoid bone. On entering the cranium it divides into two
branches, anterior and posterior. The anterior branch, the larger, crosses the great
ala of the sphenoid, and reaches the groove, or canal, in the anterior inferior angle
of the parietal bone; it then divides into two branches which spread out between the
dura and internal surface of the cranium, one passing upward over the parietal bone
as far as the vertex, and sending rami backward to the occipital bone, the other
passing front to the inner surface of the frontal bone. The posterior branch
crosses the squamous portion of the temporal, and on the inner surface of the
parietal bone divides into branches which supply the posterior part of the dura
and cranium. The branches of this vessel are distributed partly to the dura,
but chiefly to the bones; they anastomose with the arteries of the opposite side,
and with the predural and postdural arteries.
The medidural on entering the cranium gives off the following collateral
branches: 1. Numerous small vessels to the Gasserian ganglion, and to the dura
in this situation. 2. A branch, the petrosal branch (ramus petrosus super ficialis) ,
which enters the hiatus Fallopii, supplies the facial nerve, and anastomoses with
the stylo-mastoid branch of the posterior auricular artery. 3. A minute superior
tympanic branch (a. tympanica superior), which runs in the canal for the Tensor
tympani muscle, and supplies this muscle and the lining membrane of the canal.
4. Orbital branches, which pass through the sphenoidal fissure, or through separate
canals in the great wing of the sphenoid to anastomose with the lachrymal or
other branches of the ophthalmic artery. 5. Temporal or anastomotic branches,
which pass through the foramina in the great wing of the sphenoid bone and
anastomose in the temporal fossa with the deep temporal arteries.
Surgical Anatomy. — The medidural is an artery of considerable surgical importance, as
it may be injured in fractures of the temporal region of the skull. The vessel may be ruptured
by traumatism, even though the skull escapes fracture. Rupture of the medidural artery will
be followed by considerable hemorrhage between the bone and dura, which may cause
compression of the brain and require the operation of trephining for its relief. This artery
crosses the anterior inferior angle of the parietal bone at a point 1 \ inches behind the external
angular process of the frontal bone, and 1 J inches above the zygoma. From this point the ante-
rior branch passes upward and slightly backward to the sagittal suture, lying about \ inch to
J inch behind the coronal suture. The posterior branch passes upward and backward over the
squamous portion of the temporal bone. In order to expose the artery as it lies in the groove in
the parietal bone, a semilunar incision, with its convexity upward, should be made, commencing
an inch behind the external angular process, and carried backward for two inches. The struc-
616 THE BLOOD- VASCULAR SYSTEM
tures cut through are: (1) skin; (2) superficial fascia, with branches of the superficial temporal
vessels and nerves; (3) the fascia continued down from the aponeurosis of the Occipito-frontalis;
(4) the two layers of the temporal fascia; (5) the temporal muscle; (6) the deep temporal vessels;
(7) the pericranium. The bone is trephined, the clot removed, and the vessel secured by
ligatures, suture ligatures, or gauze packing.
The Parvidural or Small Meningeal Branch (parviduralis, ramus meningeus acces-
sorius) is sometimes derived from the preceding, usually from the internal maxil-
lary. It enters the skull through the foramen ovale, and supplies the Gasserian
ganglion and dura.
The Mandibular, Inferior Alveolar or Inferior Dental Branch (a. alveolaris inferior}
descends with the inferior dental nerve to the foramen on the inner side of the
ramus of the jaw. It runs along the dental canal in the substance of the bone,
accompanied by the nerve, and opposite the first bicuspid tooth divides into two
branches, the incisor and mental ; the incisor branch is continued forward beneath
the incisor teeth as far as the symphysis, where it anastomoses with the artery
of the opposite side; the mental branch (a. mentalis) escapes with the nerve at the
mental foramen, supplies the structures composing the chin, and anastomoses
with the submental, inferior labial and inferior coronary arteries. Near its origin
the inferior dental artery gives off a lingual branch, which descends with the lingual
(gustatory) nerve and supplies the mucous membrane of the mouth. As the
inferior dental artery enters the foramen it gives off a mylo-hyoid branch (ramus
mylohyoideus) , which runs in the mylo-hyoid groove, and ramifies on the under
surface of the Mylo-hyoid muscle. The dental and incisor arteries during their
course through the substance of the bone give off a few twigs which are lost in
the cancellous tissue, and a series of branches which correspond in number to
the roots of the teeth: these enter the minute apertures at the extremities of the
fangs and supply the pulp of the teeth.
Branches of the Second or Pterygoid Portion (Fig. 400) :
Deep Temporal. Masseteric.
Pterygoid. Buccal.
These branches are distributed, as their names imply, to the muscles in the
maxillary region.
The Deep Temporal Branches, two in number, anterior (a. temporalis profunda
anterior) and posterior (a. temporalis profunda posterior), each occupy that part
of the temporal fossa indicated by its name. Ascending between the Temporal
muscle and pericranium, they supply that muscle and anastomose with the middle
temporal artery. The anterior branch communicates with the lachrymal artery
through small branches which perforate the malar bone and great wing of the
sphenoid.
The Pterygoid Branches (rami pterygoidei), irregular in their number and
origin, supply the Pterygoid muscles.
The Masseteric (a. masseterica) is a small branch which passes outward, above
the sigmoid notch of the lower jaw, to the deep surface of the Masseter muscle.
It supplies that muscle, and anastomoses with the masseteric branches of the
facial and with the transverse facial artery.
The Buccal (a. buccinatoria) is a small branch which runs obliquely forward
between the Internal pterygoid and the ramus of the jaw, to the outer surface of
the Buccinator, to which it is distributed, anastomosing with branches of the
facial artery.
Branches of the Third or Spheno -maxillary Portion (Fig. 400) :
Superior Alveolar or Alveolar. Vidian.
Infraorbital. Ptery go-palatine.
Descending or Posterior Palatine. Naso- or Spheno-palatine.
THE EXTERNAL CAROTID ARTERY 617
The Superior Alveolar, Alveolar or Posterior Dental Branch (a. alveolaris superior
posterior] is given off from the internal maxillary by a common branch with the
infraorbital, and just as the trunk of the vessel is passing into the spheno-maxillary
fossa. Descending upon the tuberosity of the superior maxillary bone, it divides
into numerous branches, some of which enter the posterior dental canals, to supply
the upper molar and bicuspid teeth and the lining of the antrum, and others are
continued forward on the alveolar process to supply the gums of the upper jaw.
The Infraorbital (a. infraorbitalis) appears, from its direction, to be the con-
tinuation of the trunk of the internal maxillary. It arises from that vessel by a
common trunk with the preceding branch, and runs along the infra-orbital
canal with the superior maxillary nerve, emerging upon the face at the infra-
orbital foramen, beneath the Levator labii superioris muscle. Whilst contained
in the canal, it gives off branches which ascend into the orbit, and assist
in supplying the Inferior rectus and Inferior oblique muscles and the lachrymal
gland. Other branches, anterior dental (aa. alveolar es superiores anteriores), descend
through the anterior dental canals in the bone, to supply the mucous membrane of
the antrum and the front teeth of the upper jaw. On the face, some branches pass
upward t6 the inner angle of the orbit and the lachrymal sac, anastomosing with
the angular branch of the facial artery; other branches pass inward toward the
nose, anastomosing with the nasal branch of the ophthalmic; and other branches
descend beneath the Levator labii superioris muscle, and anastomose with the
transverse facial and buccal arteries.
The four remaining branches arise from that portion of the internal maxillary
which is contained in the spheno-maxillary fossa.
The Descending or Posterior Palatine (a. palatina descendens) descends through
the posterior palatine canal with the anterior palatine branch of Meckel's ganglion,
and, emerging from the posterior palatine foramen, runs forward in a groove on
the inner side of the alveolar border of the hard palate to the anterior palatine
canal, where the terminal branch of the artery passes upward through the fora-
men of Stenson to anastomose with the naso-palatine artery. Its branches are
distributed to the gums, the mucous membrane of the hard palate, and the
palatine glands. Whilst it is contained in the palatine canal it gives off branches
which descend in the accessory palatine canals to supply the soft palate and
tonsil, anastomosing with the ascending palatine artery.
Surgical Anatomy. — The position of the descending palatine artery on the hard palate
should be borne in mind in performing an operation for the closure of a cleft in the hard
palate, as the vessel is in danger of being wounded, and may give rise to formidable hemor-
rhage. In case it should be wounded it may be necessary to plug the posterior palatine
canal in order to arrest the bleeding. This artery may bleed furiously in the operation of
resection of the upper jaw.
The Vidian Branch (a. canalis pterygoidei) passes backward along the Vidian
canal with the Vidian nerve. It is distributed to the upper part of the pharynx
and Eustachian tube, sending a small branch into the tympanum, which anasto-
moses with the other tympanic arteries.
The Pterygo -palatine is a very small branch, which passes backward through
the pterygo-palatine canal with the pharyngeal nerve, and is distributed to the
upper part of the pharynx and Eustachian tube.
The Naso- or Spheno -palatine (a. spheno palatina) passes through the spheno-
palatine foramen into the cavity of the nose, at the back part of the superior
meatus, and divides into two branches: one internal, the naso-palatine or artery of
the septum, passes obliquely downward and forward along the septum nasi, supplies
the mucous membrane, and anastomoses in front with the terminal branch of the
descending palatine and the inferior artery of the septum, which is a branch
of the superior coronary. The external branches, two or three in number, supply
618 THE BLOOD-VASCULAR SYSTEM
the mucous membrane covering the lateral wall of the nose, the antrum, and
the ethmoid and sphenoid cells.
SURGICAL ANATOMY OF THE TRIANGLES OF THE NECK
(Fig. 269).
The student having considered the relative anatomy of the large arteries of the
neck and their branches, and the relations they bear to the veins and nerves, should
now examine these structures collectively, as they present themselves in certain
regions of the neck, in each of which important operations are constantly being
performed.
The side of the neck presents a somewhat quadrilateral outline, limited, above,
by the lower border of the body of the jaw, and an imaginary line extending from
the angle of the jaw to the mastoid process; below, by the prominent upper border
of the clavicle; in front, by the median line of the neck; behind, by the anterior
margin of the Trapezius muscle. This space is subdivided into two large triangles
by the Sterno-mastoid muscle, which passes obliquely across the neck, from the
sternum and clavicle below to the mastoid process above. The triangular space
in front of this muscle is called the anterior triangle; and that behind it, me poste-
rior triangle.
Anterior Triangle of the Neck. — The anterior triangle is bounded in front,
by an imaginary line extending from the chin to the sternum; behind, by the
anterior margin of the Sterno-mastoid; its base, directed upward, is formed by
the lower border of the body of the jaw and an imaginary line extending from
the angle of the jaw to the mastoid process; its apex is below, at the sternum.
This space is subdivided into three smaller triangles by the Digastric muscle
above and the anterior belly of the Omo-hyoid below. These smaller triangles
are named, from below upward, the inferior carotid, the superior carotid, and the
submaxillary triangle.
The Inferior Carotid Triangle or the Triangle of Necessity is bounded, in front,
by the median line of the neck; behind, by the anterior margin of the Sterno-
mastoid ; above, by the anterior belly of the Omo-hyoid ; and is covered by the
integument, superficial fascia, Platysma, and deep fascia, ramifying between
which are some of the descending branches of the superficial cervical plexus.
Beneath these superficial structures are the Sterno-hyoid and Sterno-thyroid
muscles, which, together with the anterior margin of the Sterno-mastoid, conceal
the lower part of the common carotid artery.1 The floor of this triangle is formed
by the Longus colli muscle below and by the Scalenus anticus muscle above, between
which muscles the vertebral artery and vein will be found passing into the foramen
of the transverse process of the sixth cervical vertebra. A small portion of the origin
of the Rectus capitis anticus major may also be seen on the floor of the space.
The common carotid artery is enclosed within its sheath, together with the
internal jugular vein and vagus nerve; the vein lying on the outer side of the
artery on the right side of the neck, but overlapping it below on the left side;
the nerve lying between the artery and vein, on a plane posterior to both. In
front of the sheath are a few filaments descending from the loop of communica-
tion between the Descendens and communicans hypoglossi; behind the sheath
are seen the inferior thyroid artery, the recurrent laryngeal nerve, and the sym-
pathetic nerve; and on its inner side, the trachea, the thyroid gland — much more
prominent in the female than in the male — and the lower part of the larynx. By
cutting into the upper part of this space and slightly displacing the Sterno-mastoid
muscle the common carotid artery may be tied below the Omo-hyoid muscle.
1 Therefore the common carotid artery and internal jugular vein are not, strictly speaking, contained in this
triangle, since they are covered by the Sterno-mastoid muscle; that is to say, lie behind the anterior border of
that muscle, which forms the posterior border of the triangle. But, as they lie very close to the structures
which are really contained in the triangle, and whose position it is essential to remember in operating on this
part of the artery, it has seemed expedient to study the relations of all these parts together. — ED. of 15th
English edition.
SURGICAL ANATOMY OF THE TRIANGLES OF THE NECK 619
The Superior Carotid Triangle or the Triangle of Election is bounded, behind,
by the Sterno-mastoid ; below, by the anterior belly of the Omo-hyoid; and
above, by the posterior belly of the Digastric muscle. It is covered by the
integument, superficial fascia, Platysma, and deep fascia, ramifying between
which are branches of the facial and superficial cervical nerves. Its floor is
formed by parts of the Thyro-hyoid and Hyo-glossus muscles, and the Inferior
and Middle constrictor muscles of the pharynx. This space, when dissected,
is seen to contain the upper part of the common carotid artery, which bifur-
cates opposite the upper border of the thyroid cartilage into the external and
internal carotid. These vessels are occasionally somewhat concealed from view
by the anterior margin of the Sterno-mastoid muscle, which overlaps them.
The external and internal carotid lie side by side, the external being the more
anterior of the two. The following branches of the external carotid are also
met with in this space: the superior thyroid, running forward and downward; the
lingual, directly forward; the facial, forward and upward; the occipital, back-
ward; and the ascending pharyngeal directly upward on the inner side of the
internal carotid. The veins met with are: the internal jugular, which lies on the
outer side of the common and internal carotid arteries, and veins corresponding to
the above-mentioned branches of the external carotid — viz., the superior thyroid,
the lingual, facial, ascending pharyngeal, and sometimes the occipital, all of
which accompany their corresponding arteries and terminate in the internal jugular.
The nerves in this space are the following: In front of the sheath of the common
carotid is the descendens hypoglossi. The hypoglossal nerve crosses both the
internal and external carotids above, curving round the occipital artery at its
origin. Within the sheath, between the artery and vein, and behind both, is the
vagus nerve; behind the sheath, the sympathetic. On the outer side of the vessels
the accessory nerve runs for a short distance before it pierces the Sterno-mastoid
muscle; and on the inner side of the external carotid, just below the hyoid bone,
may be seen the internal laryngeal nerve; and, still more inferiorly, the external
laryngeal nerve. The upper part of the larynx and lower part of the pharynx
are also found in the front part of this space.
The Submaxillary Triangle corresponds to the part of the neck immediately
beneath the body of the jaw. It is bounded, above, by the lower border of the
body of the jaw and a line drawn from its angle to the mastoid process; below, by
the posterior belly of the Digastric muscle and the Stylo-hyoid muscle; in front,
by the anterior belly of the Digastric. It is covered by the integument, superficial
fascia, Platysma, and deep fascia, ramifying between which are branches of the
facial and ascending filaments of the superficial cervical nerves. Its floor is formed
by the Mylo-hyoid and Hyo-glossus muscles. This space contains, in front, the sub-
maxillary gland, superficial to which is the facial vein, while imbedded in it are the
facial artery and its glandular branches; beneath this gland, on the surface of the
Mylo-hyoid muscle, are the submental artery and the mylo-hyoid artery and nerve.
The posterior part of this triangle is separated from the anterior part by the stylo-
maxillary ligament: it contains the external carotid artery, ascending deeply in
the substance of the parotid gland : this vessel here lies in front of, and superficial
to, the internal carotid, being crossed by the facial nerve, and gives off in its
course the posterior auricular, temporal, and internal maxillary branches: more
deeply are the internal carotid artery, the internal jugular vein, and the vagus
I nerve, separated from the external carotid by the Stylo-glossus and Stylo-pharyn-
geus muscles and the glosso-pharyngeal nerve.1
1 The same remark will apply to this triangle as was made about the inferior carotid triangle. The structures
enumerated as contained in the back part of the space lie, strictly speaking, beneath the muscles which form
the posterior boundary of the triangle; but as it is very important to bear in mind their close relation to the
parotid gland and its boundaries (on account of the frequency of surgical operations on this gland), all these
parts are spoken of together. — ED. of 15th English edition.
'
620 THE BLOOD-VASCULAR SYSTEM
Posterior Triangle of the Neck. — The posterior triangle is bounded, in front,
by the Sterno-mastoid muscle; behind, by the anterior margin of the Trapezius;
its base corresponds to the middle third of the clavicle; its apex, to the occiput.
The space is crossed, about an inch above the clavicle, by the posterior belly of
the Omo-hyoid, which divides it unequally into two, an upper or occipital and a
lower or subclavian triangle.
The Occipital Triangle, the larger division of the posterior triangle, is bounded,
in front, by the Sterno-mastoid; behind, by the Trapezius; below, by the Omo-
hyoid. Its floor is formed from above downward by the Splenius, Levator
anguli scapulas, and the Middle and Posterior scaleni muscles. It is covered
by the integument, the Platysma below, the superficial and deep fasciae; the
accessory nerve is directed obliquely across the space from the Sterno-mastoid,
which it pierces, to the under surface of the Trapezius; below, the descending
branches of the cervical plexus and the transversalis colli artery and vein cross the
space. A chain of lymphatic glands is also found running along the posterior
border of the Sterno-mastoid, from the mastoid process to the root of the neck.
The Subclavian Triangle, the smaller of the two posterior triangles, is bounded,
above, by the posterior belly of the Omo-hyoid; below, by the clavicle, its base,
directed forward, being formed by the Sterno-mastoid. The size of the subclavian
triangle varies according to the extent of attachment of the clavicular portion of the
Sterno-mastoid and Trapezius muscles, and also according to the height at which
the Omo-hyoid crosses the neck above the clavicle. Its height also varies much
according to the position of the arm, being much diminished by raising the limb,
on account of the ascent of the clavicle, and increased by drawing the arm down-
ward, when that bone is depressed. This space is covered by the integument,
the Platysma, the superficial and deep fasciae, and crossed by the descending
branches of the cervical plexus. Just above the level of the clavicle the third
portion of the subclavian artery curves outward and downward from the outer
margin of the Scalenus anticus, across the first rib, to the axilla. Sometimes this
vessel rises as high as an inch and a half above the clavicle, or to any point inter-
mediate between this and its usual level. Occasionally it passes in front of the
Scalenus anticus or pierces the fibres of that muscle. The subclavian vein lies
behind the clavicle, and is usually not seen in this space; but it occasionally rises
as high up as the artery, and has even been seen to pass with that vessel behind
the Scalenus anticus. The brachial plexus of nerves lies above the artery, and
in close contact with it. Passing transversely behind the clavicle are the supra-
scapular vessels, and traversing its upper angle in the same direction, the trans-
versalis colli artery and vein. The external jugular vein runs vertically downward
behind the posterior border of the Sterno-mastoid muscle, to terminate in the
subclavian vein; it receives the transverse cervical and suprascapular veins, which
occasionally form a plexus in front of the artery, and a small vein which crosses
the clavicle from the cephalic. The small nerve to the Subclavius muscle also
crosses this triangle about its middle. A lymphatic gland is also found in the space.
Its floor is formed by the first rib with the first digitation of the Serratus magnus.
The Internal Carotid Artery (A. Carotis Interna).
The internal carotid artery supplies the anterior part of the brain, the eye,
and its appendages, and sends branches to the forehead and nose. Its size
in the adult is equal to that of the external carotid, though in the child it is
larger than that vessel. It is remarkable for the number of curvatures that it
presents in different parts of its course. It occasionally has one or two flexures
near the base of the skull, whilst in its passage through the carotid canal and
along the side of the body of the sphenoid bone it describes a double curve
which resembles somewhat the letter S placed horizontally. These curvatures most
THE INTERNAL CAROTID ARTERY
621
probably diminish the velocity of the current of blood, by increasing the extent of
surface over which it moves and adding to the impediment produced from friction.
In considering the course and relations of this vessel it may be conveniently
divided into four portions: the cervical, petrous, cavernous, and cerebral portions.
Cervical Portion. — This portion of the internal carotid commences at the
bifurcation of the common carotid, opposite the upper border of the thyroid
M Aortic
FIG. 401. — The internal carotid and vertebral arteries. Right side.
cartilage, and runs perpendicularly upward, in front of the transverse processes
of the three upper cervical vertebrae, to the carotid canal in the petrous portion
of the temporal bone. It is superficial at its commencement, being contained in the
superior carotid triangle, and lying on the same level as the external carotid, but
behind that artery overlapped by the Sterno-mastoid and covered by the deep
622 THE BLOOD-VASCULAR SYSTEM
fascia, Platysma, and integument: it then passes beneath the parotid gland, being
crossed by the hypoglossal nerve, the Digastric and Stylo-hyoid muscles, and
the occipital and posterior auricular arteries. Higher up, it is separated from the
external carotid by the Stylo-glossus and Stylo-pharyngeus muscles, the glosso-
pharyngeal nerve, and pharyngeal branch of the vagus.
Relations. — It is in relation, behind, with the Rectus capitis anticus major, the
superior cervical ganglion of the sympathetic, and superior laryngeal nerve; exter-
nally, with the internal jugular vein and vagus nerve, the nerve lying on a plane
posterior to the artery; internally, with the pharynx, tonsil, the superior laryngeal
nerve, and ascending pharyngeal artery. At the base of the skull the glosso-
pharyngeal, vagus, accessory, and hypoglossal nerves lie between the artery and
the internal jugular vein.
PLAN OF THE RELATIONS OF THE INTERNAL CAROTID ARTERY IN THE NECK.
In front.
Skin, superficial and deep fasciae.
Platysma.
Sterno-mastoid.
Occipital and posterior auricular arteries.
Hypoglossal nerve.
Parotid gland.
Stylo-glossus and Stylo-pharyngeus muscles.
Glosso-pharyngeal nerve.
Pharyngeal branch of the vagus.
Externally. / \ Internally.
Internal jugular vein. / Carotid1 ) Pharynx.
Vagus nerve. \ Artery. 1 Superior laryngeal nerve.
V / Ascending pharyngeal artery.
Tonsil.
Behind.
Rectus capitis anticus major.
Sympathetic.
Superior laryngeal nerve.
Petrous Portion. — When the internal carotid artery enters the canal in the
petrous portion of the temporal bone, it first ascends a short distance, then curves
forward and inward, and again ascends as it leaves the canal to enter the cavity of
the skull between the lingula and petrosal process. In this canal the artery lies
at first in front of the cochlea and tympanum ; from the latter cavity it is separated
by a thin, bony lamella, which is cribriform in the young subject, and is often
absorbed in old age. Farther forward it is separated from the Gasserian ganglion
by a thin plate of bone, which forms the floor of the fossa for the ganglion and the
roof of the horizontal portion of the canal. Frequently this bony plate is more
or less deficient, and then the ganglion is separated from the artery by a fibrous
membrane. The artery is separated from the bony wall of the carotid canal by a
prolongation of the dura, and is surrounded by a number of small veins and
by filaments of the carotid plexus, derived from the ascending branch of the
superior cervical ganglion of the sympathetic.
Cavernous Portion. — The internal carotid artery in this part of its course is
situated between the layers of the dura forming the cavernous sinus, but is covered
by the lining membrane of the sinus. It at first ascends to the posterior clinoid
process, then passes forward by the side of the body of the sphenoid bone, and
again curves upward on the inner side of the anterior clinoid process, and per-
forates the dura, forming the roof of the sinus. In this part of its course it is
surrounded by filaments of the sympathetic nerve, and has in relation with it
externally the abducent nerve.
THE INTERNAL CAROTID ARTERY 623
Cerebral Portion. — Having perforated the dura, on the inner side of the anterior
clinoid process, the internal carotid passes between the optic and oculomotor
nerves to the preperforatum at the inner extremity of the fissure of Sylvius, where
it gives off its terminal or cerebral branches. This portion of the artery has the
optic nerve on its inner side, and the oculomotor nerve externally.
Peculiarities. — The length of the internal carotid varies according to the length of the neck,
and also according to the point of bifurcation of the common carotid. Its origin sometimes
takes place from the arch of the aorta; in such rare instances this vessel has been found to be
placed nearer the middle line of the neck than the external carotid, as far upward as the larynx,
when the latter vessel crossed the internal carotid. The course of the vessel, instead of being
straight, may be very tortuous. A few instances are recorded in which this vessel was altogether
absent: in one of these the common carotid passed up the neck, and gave off the usual branches
of the external carotid, the cranial portion of the internal carotid being replaced by two branches
of the internal maxillary, which entered the skull through the foramen rotundum and the foramen
ovale and joined to form a single vessel.
Surgical Anatomy. — The cervical part of the internal carotid is very rarely wounded. Mr.
Cripps, in an interesting paper in the Medico-Chirurgical Transactions, compares the rareness
of a wound of the internal carotid with one of the external carotid or its branches. It is, however,
sometimes injured by a stab or gunshot wound in the neck, or even occasionally by a stab from
within the mouth, as when a person receives a thrust from the end of a parasol or falls down
with a tobacco-pipe in his mouth. It used to be believed that the internal carotid was occa-
sionally wounded in the removal of the tonsil. Such an accident cannot happen if the artery is
normally placed. The severe and sometimes fatal hemorrhage which has followed this opera-
tion in a few instances probably had as its source enlarged branches of the ascending pharyn-
geal, tonsillar, or ascending palatine arteries. Recently, however, Dr. Gwilym G. Davis, of
Philadelphia, demonstrated a specimen in which the internal carotid could have been wounded
by incision of the tonsil. The indications for ligature are wounds, when the vessel should be
exposed by a careful dissection and tied above and below the bleeding point; and aneurism,
which if non-traumatic may be treated by ligature of the common carotid, but if traumatic in
origin by exposing the sac and tying the vessel above and below. The incision for ligature of
the cervical portion of the internal carotid should be made along the anterior border of the
Sterno-mastoid, from the angle of the jaw to the upper border of the thyroid cartilage. The
superficial structures being divided and the SteAo-mastoid defined and drawn outward, the
cellular tissue must be carefully separated and the posterior belly of the Digastric muscle and
the hypoglossal nerve sought for as guides to the vessel. When the artery is found the external
carotid should be drawn inward and the Digastric muscles upward, and the aneurism needle
passed from without inward.
Branches. — The branches given off from the internal carotid artery are —
From the Petrous portion . Tympanic (internal or deep).
( Arterise Receptaculi.
From the Cavernous portion < Predural, or Anterior Meningeal.
(^ Ophthalmic.
rPrecerebral, or Anterior Cerebral.
Medicerebral, or Middle Cerebral.
From the Cerebral portion . j Postcommunicantj or Posterior Communicating.
(^Prechoroid, or Anterior Choroid.
The cervical portion of the internal carotid gives off no branches.
The Tympanic (ramus caroticotympanicus] is a small branch from the petrous
portion, which enters the cavity of the tympanum through a minute foramen in
the carotid canal, and anastomoses with the tympanic branch of the internal
maxillary, and with the stylo-mastoid artery.
The Arteriae Receptaculi are numerous small vessels, derived from the inter-
nal carotid in the cavernous sinus; they supply the pituitary body, the Gasserian
ganglion, and the walls of the cavernous and inferior petrosal sinuses. Some of
these branches anastomose with branches of the medidural.
The Predural or Anterior Meningeal (a. praeduralis, a. meningea anterior} is a
small branch which passes over the lesser wing of the sphenoid to supply the dura
of the anterior fossa; it anastomoses with the dural branch from the posterior
ethmoid al artery.
624
THE BLOOD-VASCULAR SYSTEM
The Ophthalmic Artery (a. ophthalmica) arises from the internal carotid,
just as that vessel is emerging from the cavernous sinus, on the inner side of the
anterior clinoid process, and enters the orbit through the optic foramen, below and
Nasal. Palpebral.
Supra-orbital.
Anterior ethmoidal.
Posterior ethmoidal.
Muscular.
Temporal branches
Arterial J of
centralis retinse.
Ophthalmic-
Internal carotid.
FIG. 402. — The ophthalmic artery and its branches, the roof of the orbit having been removed.
on the outer side of the optic nerve. It then passes over the nerve to the inner wall
of the orbit, and thence horizontally forward, beneath the lower border of the
Superior oblique muscle, to a point behind the internal angular process of the
frontal bone, where it divides into two terminal branches, the frontal and nasal
branches. As the artery crosses the optic nerve it is accompanied by the nasal
nerve, and is separated from the frontal nerve by the Rectus superior and
Levator palpebrse superioris muscles.
Branches. — The branches of this vessel may be divided into an orbital group,
which are distributed to the orbit and surrounding parts, and an ocular group,
which supply the muscles and globe of the eye:
Orbital Group.
Lachrymal.
Supraorbital.
Posterior Ethmoidal.
Anterior Ethmoidal.
Internal Palpebral.
Frontal.
Nasal.
Ocular Group.-
Short Ciliary.
Long Ciliary.
Anterior Ciliary.
Arteria Centralis Retinae.
Muscular.
The Lachrymal (a. lachrimalis) is one of the largest branches derived from the
ophthalmic, arising close to the optic foramen; not infrequently it is given off from
the ophthalmic artery before it enters the orbit. It accompanies the lachrymal nerve
along the upper border of the External rectus muscle, and is distributed to the
THE INTKItXAL CAROTID ARTERY 625
lachrymal gland. Its terminal branches, escaping from the gland, are distributed to
the eyelids and conjunctiva : of those supplying the eyelids, two are of considerable
size and are named the external palpebral ; they run inward in the upper and lower
lids respectively, and anastomose with the internal palpebral arteries, forming an
arterial circle in this situation. The lachrymal artery gives off one or two malax
branches, one of which passes through a foramen in the malar bone, to reach the
temporal fossa, and anastomoses with the deep temporal arteries; the other appears
on the cheek through the malar foramen, and anastomoses with the transverse facial.
A branch, the recurrent, is also sent backward through the sphenoidal fissure to the
dura, which anastomoses with a branch of the medidural artery.
Peculiarities. — The lachrymal artery is sometimes derived from one of the anterior branches
of the medidural artery.
The Supraorbital Artery (a. supraorbitalis) arises from the ophthalmic as that
vessel is crossing over the optic nerve. Ascending so as to arise above all the muscles
of the orbit, it passes forward, with the supraorbital nerve, between the periosteum
and Levator palpebne muscle; and, passing through the supraorbital foramen,
divides into a superficial and deep branch, which supply the integument, the
muscles, and the pericranium of the forehead, anastomosing with the frontal, the
anterior branch of the temporal, and the supraorbital artery of the opposite side.
This artery in the orbit supplies the Superior rectus and the Levator palpebne
muscles, and sends a branch inward, across the pulley of the Superior oblique
muscle, to supply the parts at the inner canthus. At the supraorbital foramen
it frequently transmits a branch to the diploe.
The Ethmoidal Branches are two in number— posterior (a. ethmoidalis posterior)
and anterior (a. ethmoidalis anterior). The former, which is the smaller, passes
through the posterior ethmoidal foramen, supplies the posterior ethmoidal cells,
and, entering the cranium, gives off a dural or meningeal branch, which supplies the
adjacent dura; and nasal branches which descend into the nose through aper-
tures in the cribriform plate, anastomosing with branches of the spheno-palatine.
The anterior ethmoidal artery accompanies the nasal nerve through the anterior
ethmoidal foramen, supplies the anterior ethmoidal cells and frontal sinuses, and,
entering the cranium, gives off a dural branch which supplies the adjacent dura;
and nasal branches, which descend into the nose, through the slit by the side of
the crista galli, and, running along the groove on the under surface of the nasal
bone, supply the skin of the nose.
The Internal Palpebral Arteries (aa. palpebrales mediates), two in number, supe-
rior and inferior, arise from the ophthalmic, opposite the pulley of the Superior
oblique muscle; they leave the orbit to encircle the eyelids near their free margin,
forming a superior tarsal arch (arcus tarseus superior} and an inferior tarsal arch (arcus
tarseus inferior), which lie between the Orbicularis muscle and the tarsal plates;
the superior palpebral inosculating at the outer angle of the orbit with the orbital
branch of the temporal artery, and with the upper of the two external palpebral
branches from the lachrymal artery — the inferior palpebral inosculating, at the
outer angle of the orbit, with the lower of the two external palpebral branches
from the lachrymal and with the transverse facial artery, and at the inner side
of the lid with a branch from the angular artery. From this last anastomosis a
branch passes to the nasal duct, ramifying in its mucous membrane, as far as the
inferior meatus.
The Frontal Artery (a. frontalis), one of the terminal branches of the ophthalmic,
passes from the orbit at its inner angle, and, ascending on the forehead, supplies
the integument, muscles, and pericranium, anastomosing with the supraorbital
artery and with the frontal artery of the opposite side.
40
626
THE BLOOD-VASCULAR SYSTEM
The Nasal Artery (a. dorsalis nasi), the other terminal branch of. the ophthalmic,,
emerges from the orbit above the tendo oculi, and, after giving a branch to the
upper part of the lachrymal sac, divides into two branches, one of which crosses
the root of the nose, the transverse nasal, and anastomoses with the angular artery;
the other, the dorsalis nasi, runs along the dorsum of the nose, supplies its outer
surface, and anastomoses with the artery of the opposite side and with the lateral
nasal branch of the facial.
FIG. 403. — The arteries of the base of the brain. The right half of the cerebellum and pons have been re-
moved. N. B. — It will be noticed that the two precerebral arteries have been drawn at a considerable distance
from each other: this makes the precommunicant artery appear very much longer than it really is.
THE INTERNAL CARO1ID ARTERY
627
The Ciliary Arteries (a. ciliares) are divisible into three groups, the short, long,
and anterior. The short ciliary arteries (aa. ciliaris posteriores breves), from six
to twelve in number, arise from the ophthalmic or some of its branches; they sur-
round the optic nerve as they pass forward to the posterior part of the eyeball,
pierce the sclerotic coat around the entrance of the nerve, and supply the choroid
coat and ciliary processes. The long ciliary arteries (aa. ciliares posteriores longae) ,
two in number, pierce the posterior part of the sclerotic at some little distance from
the optic nerve, and run forward, along each side of the eyeball, between the
sclerotic and choroid, to the ciliary muscle, where they divide into two branches;
these form an arterial circle, the circulus major, around the circumference of the
iris, from which numerous radiating branches pass forward, in its substance, to
its free margin, where they form a second arterial circle, the circulus minor, around
its pupillary margin. The anterior ciliary arteries (aa. ciliares anteriores) are
Fro. 404. — Vascular area 'of the upper surface of the cerebrum. I. The part supplied by the external and
inferior frontal artery. II. The part supplied by the ascending frontal. III. The part supplied by the
ascending parietal. IV. The part supplied by the sphenoparietal artery. (After Duret.)
derived from the muscular branches; they pass to the front of the eyeball in com-
pany with the tendons of the Recti muscles, form a vascular zone beneath the
conjunctiva, and then pierces the sclerotic a short distance from the cornea and
terminate in the circulus major of the iris.
The Arteria Centralis Retinae is the first and one of the smallest branches of the
ophthalmic artery. It runs for a short distance within the dural sheath of the
optic nerve, but about half an inch behind the eyeball it pierces the optic nerve
obliquely, and runs forward in the centre of its substance, and enters the globe
of the eye through the porus opticus. Its mode of distribution will be described
in the account of the anatomy of the eye.
The Muscular Branches (rami musculares) , two in number, superior and inferior,
frequently spring from a common trunk. The superior, the smaller, often wanting,
628
THE BLOOD-VASCULAR SYSTEM
supplies the Levator palpebrse, Superior rectus, and Superior oblique. The infe-
rior, more constant in its existence, passes forward between the optic nerve and
the Inferior rectus muscle, and is distributed to the External, Internal, and
Inferior recti, and Inferior oblique. This vessel gives off most of the anterior
ciliary arteries. Additional muscular branches are given off from the lachrymal
and supraorbital arteries or from the ophthalmic itself.
(For the Circulus or Circle of Willis, the postcerebral artery, and the blood-
vessels of the cerebellum, see page 642.)
The Precerebral or Anterior Cerebral (a. praecerebralis, a. cerebri anterior)
arises from the internal carotid at the inner extremity of the fissure of Sylvius. It
passes forward and inward across the preperforatum, above the optic nerve, to the
commencement of the intercerebral fissure. Here it comes into close relationship
with the precerebral artery of the opposite side, and the two vessels are connected
together by a short anastomosing trunk, about two lines in length, the precommuni-
cant or anterior communicating artery. From this point the two vessels run side by
Central Fissure
Occipital
'Fissure
FIG. 405. — Vascular area of the internal surface of the cerebrum. I. The part supplied by the anterior
internal frontal. II. The part supplied by the middle internal frontal. III. The part supplied by the posterior
internal frontal. IV. The part supplied by the posterior temporal. V. The part supplied by the occipital, both
terminal branches of the posterior cerebral. (After Duret.)
side in the intercerebral fissure, curve round thegenu of the callosum,and, turning
backward, continue along its upper surface to its posterior part, where they ter-
minate by anastomosing with the postcerebral arteries.
Branches. — In their course the precerebral arteries give off the following
branches :
Antero-median ganglionic. Anterior internal frontal.
Inferior internal frontal. Middle internal frontal.
Posterior internal frontal.
The Antero-median Ganglionic is a group of small arteries which arise at the
commencement of the precerebral artery; they pierce the preperforatum and
terma, and supply the head of the caudatum.
The Inferior Internal Frontal Branches or the Internal Orbital Arteries, two or
three in number, are distributed to the orbital surface of the frontal lobe, where
they supply the olfactory lobe, gyrus rectus, and internal orbital convolution.
The Anterior Internal Frontal supplies a part of the marginal convolution, and
sends branches over the edge of the hemisphere to the superfrontal and medifrontal
gyre and upper part of the precentral gyre.
THE INTERNAL CAROTID ARTERY
629
The Middle Internal Frontal supplies the callosum, the callosal gyre, the inesal
surface of the superfrontal convolution, and the dorsal part of the precentral gyre.
The Posterior Internal Frontal supplies the quadrate lobe and adjacent outer
surface of the hemisphere.
The Precommunicant or Anterior Communicating Artery (a. praecommunicans, a.
communicans anterior] is a short branch, about two lines in length, but of moderate
diameter, connecting together the two precerebral arteries across the intercerebral
fissure. Sometimes this vessel is wanting, the two arteries joining together to form
a single trunk, which afterward divides. Or the vessel may be wholly or partially
divided into two; frequently it is longer and smaller than usual. It gives off some
of the antero-median ganglionic group of vessels, which are, however, principally
derived from the precerebral.
FIG. 406. — Vascular area of the inferior surface of the cerebrum. I. The part supplied by the anterior
temporal from the postcerebral artery. II. The part supplied by the posterior temporal from the postcere-
bral artery. III. The part supplied by the occipital from the postcerebral artery. (After Duret.)
The Medicerebral or Middle Cerebral Artery (a. medicerebralis, a. cerebri
media) (Fig. 407), the largest branch of the internal carotid, passes obliquely
outward along the fissure of Sylvius, and opposite the island of Reil divides into
temporal and parieto-temporal terminal branches.
Branches.— The branches of the medicerebral artery are —
Antero-lateral ganglionic.
Inferior external frontal.
Parieto-temporal.
Ascending frontal.
Ascending parietal.
The Antero-lateral Ganglionic Branches are a group of small arteries which arise
at the commencement of the medicerebral artery; they pierce the preperforatum
and supply the greater part of the caudatum, the lenticular nucleus, the internal
630 THE BLOOD-VASCULAR SYSTEM
capsule, and a part of the optic thalamus. One artery of this group (one of the
lenticulo-striate arteries) is of larger size than the rest, and is of special importance,
as being the artery in the brain most frequently ruptured; it has been termed by
Charcot the artery of cerebral hemorrhage. It passes up between the lenticular
nucleus and the external capsule, and ultimately ends in the caudatum.
The Inferior External Frontal supplies the third or subfrontal convolution
(Broca's convolution) and the outer part of the orbital surface of the frontal lobe.
The Ascending Frontal supplies the precentral gyre.
The Ascending Parietal supplies the ascending parietal convolution and the
lower part of the superior parietal convolution.
The Parieto-temporal or Parieto-sphenoidal supplies the supramarginal, the
supertemporal, and part of the meditemporal gyre, and the angular gyrus.
ANTERO-IATERAL
6ANSLIONIC OR PER-
FORATING BRANCH[$
MEDICCREBRAL ARTERY
FIG. 407. — The distribution of the medicerebral artery. (After Charcot.)
The Postcommunicant or Posterior Communicating Artery (a. postcommuni-
cans, a. communicans posterior] arises from the back part of the internal carotid , runs
directly backward, and anastomoses with the postcerebral, a branch of the basilar.
This artery varies considerably in size, being sometimes small, and occasionally
so large that the postcerebral may be considered as arising from the internal
carotid rather than from the basilar. It is frequently larger on one side than on the
other side. From the posterior half of this vessel are given off a number of small
branches, the postero-median ganglionic branches, which, with similar vessels from
the postcerebral, pierce the postperforatum and supply the internal surfaces of the
optic thalami and the walls of the third ventricle.
The Prechoroid or Anterior Choroid (a. praechoroidea, a. chorioidea] is a small
but constant branch which arises from the back part of the internal carotid, near
the postcommunicant artery. Passing backward and outward between the tem-
poral lobe and the crus, it enters the medicornu of the lateral ventricle through
the choroid fissure and ends in the paraplexus. It is distributed to the hippo-
campus, fimbria, velum, and paraplexus.
THE BLOOD-VESSELS OF THE BRAIN.
Recent investigations have tended to show that the mode of distribution of
the vessels of the brain has an important bearing upon a considerable number of
THE BLOOD-VESSELS OF THE BMAIN
631
the anatomical lesions of which this part of the nervous system may be the seat;
it therefore becomes important to consider a little more in detail the way in which
the cerebral vessels are distributed.
The cerebral arteries are derived from the internal carotid and the vertebral,
which at the base of the brain form a remarkable anastomosis known as the cir-
culus or circle of Willis (see page 642). The tortuosity of the constituent vessels
of the anastomosis lessens the impact of the circulation and saves the brain from
damage. The outline of the vessels forming the so-called circle is said by Sappey
to be hexagonal, and by Testut to be heptagonal. The circulus is formed in front
bv the precerebral arteries, branches of the internal carotid, which are connected
together 'by the precommunicant; behind by the two postcerebrals, branches of the
bjisilar, which are connected on each side to the internal carotid by the postcom-
municant (Fig. 403). The parts of the brain included within this arterial circle
are the terma, the chiasm or commissure of the optic nerves, the tuber, the albi-
~^< Precerebral artery.
/Internarcarotid artery.
\
Medicerebral artery.
FIG. 408. — Diagram of the arterial circulation at the base of the brain. I. Antero-median group of ganglionic
branches. II. Postero-median group. III. Right and left anterq-lateral group. IV. Right and left postero-
lateral group. The dotted line shows the limit of the ganglionic circle. (After Charcot.)
cantia, and the postperforatum. This arrangement of the vessels of the circulus is
not invariable; according to Windle it is maintained in little more than half the
recorded cases. In the other cases there are various anomalies.
From the circulus arise the three trunks which together supply each cerebral
hemisphere. From its anterior part proceed the two precerebrals, from its antero-
lateral part the medicerebrals, and from its posterior part the postcerebrals.
Each of these principal arteries gives origin to two very different systems of
secondary vessels. One of these systems has been named the central ganglionic
system, and the vessels belonging to it supply the central ganglia of the brain; the
other has been named the cortical arterial system, and its vessels ramify in the
pia and supply the cortex and subjacent medullary matter. These two systems,
although they have a common origin, do not communicate at any point of their
peripheral distribution, and are entirely independent of each other. Though some
of the arteries of the cortical system approach, at their terminations, the regions
632
THE BLOOD-VASCULAR SYSTEM
supplied by the central ganglionic system, no communication between the two
sets of vessels takes place, and there is between the parts supplied by the two
systems a borderland of diminished nutritive activity. In the brains of old people
softening is especially apt to occur in this ill-nourished territory.
The Central Ganglionic System. — All the vessels belonging to this system
are given off from the circulus or from the vessels immediately after their origin
from it, so that if a circle is drawn at a distance of about an inch from the circulus,
it will include the origin of all the arteries belonging to this system (Fig. 408).
The vessels of this system form six principal groups: (I.) the antero-median group,
derived from the precerebrals and precommunicans ; (II.) the postero-median group,
from the postcerebrals and postcommunicans ; (III.) the right and left antero-
lateral group, from the medicerebrals; and (IV.) the right and left postero-lateral
group, from the postcerebrals, after they have wound round the crura. The vessels
belonging to this system are larger than those of the cortical system, and are what
FIG. 409. — Distribution of the cortical arteries. 1. Medullary arteries. 1'. Group of medullary arteries in
the sulcus between two adjacent convolutions. 1". Arteries situated among the short association fibres. 2, 2.
Cortical arteries, a. Capillary network with fairly wide meshes, situated beneath the pia. 6. Network with
more compact, polygonal meshes, situated in the cortex, c. Transitional network with wider meshes, d.
Capillary network in the white matter. (After Charcot.)
Cohnheim has termed terminal arteries; that is to say, vessels which from their
origin to their termination neither supply nor receive any anastomotic branches,
so that by one of the small vessels only a limited area of the central ganglia can
be injected ; and the injection cannot be driven beyond the area of the part sup-
plied by the particular vessel which is the subject of the experiment.
The Cortical Arterial System. — The vessels forming this system are the ter-
minal branches of the pre-, medi-, and postcerebral arteries, described above.
These vessels divide and ramify in the substance of the pia, and give off nutrient
arteries which penetrate the cortex perpendicularly. These nutrient vessels are
divisible into two classes — the long and short. The long — or, as they are some-
times called, the medullary — arteries pass through the gray matter to penetrate
the centrum ovale to the depth of about an inch and a half, without intercom-
municating otherwise than by very fine capillaries, and thus constitute so many
THE 8UBCLA VIAN ARTERY C33
independent small systems. The short vessels are confined to the cortex, where
ihrv form with the long vessels a compact network in the middle zone of the gray
matter, the outer and inner zones being sparingly supplied with blood (Fig. 409).
The vessels of the cortical arterial system are not so strictly terminal as those of the
central ganglionic system, but they approach this type very closely, so that injec-
tion of one area from the vessel of another area, though it may be possible, is fre-
quently very difficult, and is only effected through vessels of small calibre. As a
result of this, obstruction of one of the main branches or its divisions may have
the effect of producing softening in a very limited area of the cortex.1
ARTERIES OF THE UPPER EXTREMITY.
The artery which supplies the upper extremity continues as a single trunk
from its commencement down to the elbow, but different portions of it have
received different names according to the region through which it passes. That
part of the vessel which extends from its origin to the outer border of the first
rib is termed the subclavian artery ; beyond this point to the lower border of the
axilla-it is termed the axillary artery; and from the lower margin of the axillary space
to the bend of the elbow it is termed the brachial artery; here the single trunk
terminates by dividing into two branches, the radial and ulnar — an arrangement
precisely similar to what occurs in the lower limb.
THE SUBCLAVIAN ARTERY (A. SUBCLAVIA) (Fig. 410).
The subclavian artery on the right side arises from the innominate artery
opposite the right sterno-clavicular articulation; on the left side it arises from
the arch of the aorta. It follows, therefore, that these two vessels must, in the first
part of their course, differ in their length, their direction, and their relation with
neighboring parts.
In order to facilitate the description of these vessels, more especially from a
surgical point of view, each subclavian artery has been divided into three parts.
The first portion, on the right side, passes upward and outward from the origin
of the vessel to the inner border of the Scalenus anticus. On the left side it ascends
nearly vertically, to gain the inner border of that muscle. The second part passes
outward, behind the Scalenus anticus; and the third part passes from the outer
margin of that muscle, beneath the clavicle, to the outer border of the first rib,
where it becomes the axillary artery. The first portion of these two vessels differs
so much in its course and in its relations with neighboring parts that it will be
described separately. The second and third parts are alike on the two sides.
First Part of the Right Subclavian Artery (Figs. 389, 390, 394, 410).
On the right side the subclavian artery arises from the arteria innominata, oppo-
site the upper part of the right sterno-clavicular articulation, and passes upward
and outward to the inner margin of the Scalenus anticus muscle (Figs. 389, 390,
and 410). In this part of its course it ascends a little above the clavicle, the extent
to which it does so varying in different cases.
Relations. — It is covered, in front, by the integument, superficial fascia, Platysma,
deep fascia, the clavicular origin of the Sterno-mastoid, the Stern o-hyoid, and
the Sterno-thyroid muscles, and a second layer of deep fascia. It is crossed
by the internal jugular and vertebral veins, and by the vagus nerve and the
1 The student who desires further information on this subject is referred to Charcot's Localization of Cerebral
and Spinal Diseases, p. 42 et seg., whence the facts above given have been principally derived. — ED. of 15th
English edition.
034
THE BLOOD-VASCULAR SYSTEM
cardiac branches of the sympathetic nerve. A loop of the sympathetic nerve
itself also crosses the artery, forming a ring around the vessels. The anterior
jugular vein passes outward in front of the artery but is not in contact with it,
being separated from it by the Sterno-hyoid and Sterno-thyroid muscles. Below
and behind the artery is the pleura, which separates it from the apex of the lung;
behind is the cord of the sympathetic nerve; the recurrent laryngeal nerve winds
round the lower and back part of the vessel.
Phrenic nerve.
I
Vertebral artery.
'erior thyroid artery.
Supra-scapular
artery.
Supra-
scapular
nerve.
Vagus nerve.
Subclaman
artery.
External jugu-
lar vein.
.Right innmili-
nate vein.
Innomi-
nate artery.
«&\
' Profunda artery.
-Muscido-spiral nerve.
FIG. 410. — The subclavian artery, showing its relations. (From a preparation in the Museum of the Royal
College of Surgeons of England.)
PLAN OF THE RELATIONS OF FIRST PORTION OF THE RIGHT SUBCLAVIAN ARTERY.
In front.
Skin, superficial fascia.
Platysma, deep fascia.
Clavicular origin of Sterno-mastoid.
Sterno-hyoid and Sterno-thyroid.
Anterior jugular, Internal jugular, and vertebral veins.
Vagus and cardiac nerves.
Loop from the sympathetic.
Beneath.
Pleura.
Recurrent laryngeal nerve.
THE SUBCLAVIAN ARTERY 635
Behind.
Recurrent laryngeal nerve.
Sympathetic.
Pleura and apex of lung.
First Part of the Left Subclavian Artery (Figs. 388, 389).
The left subclavian artery arises from the end of the arch of the aorta, opposite
the fourth thoracic vertebra, and ascends nearly vertically to the inner margin of
the Scalenus anticus muscle. This part of the vessel is, therefore, longer than the
right, is situated deeply in the cavity of the chest, and is directed nearly vertically
upward, instead of arching outward like the vessel of the opposite side.
Relations. — It is in relation, in front, with the vagus, cardiac, and phrenic
nerves, which lie parallel with it, the left carotid artery, left internal jugular
and vertebral veins, and the commencement of the left innominate vein and is
covered by the Sterno-thyroid, Sterno-hyoid, and Sterno-mastoid muscles; behind,
it is in relation with the oesophagus, thoracic duct, inferior cervical ganglion of the
sympathetic, and Longus colli muscle; higher up, however, the oesophagus and
tlioracic duct lie to its right side; the latter ultimately arching over the vessel to
join the angle of union between the subclavian and internal jugular veins. To
its inner side are the oesophagus, trachea, and thoracic duct; to its outer side, the
left pleura and lung.
PLAN OF THE RELATIONS OF FIRST PORTION OF THE LEFT SUBCLAVIAN ARTERY.
In front.
Vagus, cardiac, and phrenic nerves.
Left carotid artery.
Thoracic duct.
Left internal jugular, vertebral, and in-nominate veins.
Sterno-thyroid, Sterno-hyoid, and Sterno-mastoid muscles.
Inner side. / ^ Outer side.
Trachea. [ &n^l.an \ Pleura and left lung.
(Esophagus.
Thoracic duct.
Behind.
(Esophagus and thoracic duct.
Inferior cervical ganglion of sympathetic.
Longus colli.
Second and Third Parts of the Subclavian Artery (Figs. 392, 410).
The Second Portion of the Subclavian Artery lies behind the Scalenus anticus
muscle; it is very short, and forms the highest part of the arch described by that
vessel.
Relations. — It is covered, in front, by the skin, superficial fascia, Platysma,
deep cervical fascia, the Sterno-mastoid and the Scalenus anticus muscles. On
the right side the phrenic nerve is separated from the second part of the artery by
the Scalenus anticus muscle, while on the left side the nerve crosses the first part
of the artery immediately to the inner edge of the muscle. Behind, it is in rela-
tion with the pleura and the Scalenus medius muscle. Above, with the br'achial
plexus of nerves. Below, with the pleura. The subclavian vein lies below and
in front of the artery, separated from it by the Scalenus anticus muscle.
636 THE BLOOD- VASCULAR SYSTEM
PLAN OF THE RELATIONS OF SECOND PORTION OF SUBCLAVIAN ARTERY.
In front.
Skin and superficial fascia.
Platysma and deep cervical fascia.
Sterno-mastoid .
Phrenic nerve.
Scalenus anticus.
Subclavian vein.
A 7 / Subclavian \ »> 7
Above. I Artery. ] BelOW.
Brachial plexus. ( *™»* j Pleura.
Behind.
Pleura and Middle Scalenus.
The Third Portion of the Subclavian Artery passes downward and outward
from the outer margin of the Scalenus anticus muscle to the outer border of the
first rib, where it becomes the axillary artery. This portion of the vessel is the
most superficial, and is contained in the subclavian triangle (see page 620).
Relations. — It is covered, in front, by the skin, the superficial fascia, the Platysma
the descending clavicular branches of the cervical plexus, and the deep cervical
fascia; by the clavicle, the Subclavius muscle, the suprascapular artery and
vein, and the transverse cervical vein; the nerve to the Subclavius muscle passes
vertically downward in front of the artery. The external jugular vein crosses
the artery at its inner side, and receives the suprascapular and transverse cervical
veins, which frequently form a plexus in front of it. The subclavian vein is
below and in front of the artery, lying close behind the clavicle. Behind, it lies on
the Middle scalenus muscle and the lowest cord of the brachial plexus, formed
by the union of the last cervical and first thoracic nerves. Above it, and to its
outer side, is the brachial plexus and Omo-hyoid muscle. Beloiv, it rests on the
upper surface of the first rib.
PLAN OF THE RELATIONS OF THIRD PORTION OF SUBCLAVIAN ARTERY.
In front.
Skin and superficial fascia.
Platysma and deep cervical fascia.
Descending branches of cervical plexus. Nerve to Subclavius muscle.
Subclavius muscle, suprascapular artery, and vein.
The external jugular and transverse cervical veins.
The clavicle.
/ Subclavian \
Above. I Artery. 1 BelOW.
Brachial plexus. I portion. / First rib.
Omo-hyoid. \. y
Behind.
Scalenus medius.
Lower cord of brachial plexus.
Peculiarities. — The subclavian arteries vary in their origin, their course, and the height to
which they rise in the neck.
The origin of the right subclavian from the innominate takes place, in some cases, above the
sterno-clavicular articulation, and occasionally, but less frequently, in the cavity of the thorax,
below that point. Or the artery may arise as a separate trunk from the arch of the aorta. In
such cases it may be either the first, second, third, or even the last branch derived from that
vessel; in the majority of cases it is the first or last, rarely the second or third. When it is the first
branch, it occupies the ordinary position of the innominate artery; when the second or third, it
gains its usual position by passing behind the right carotid; and when the last branch, it arises
from the left extremity of the arch, at its upper or back part, and passes obliquely toward the
THE SUBCLA VI AN ARTERY 637
right side, usually behind the trachea, oesophagus, and right carotid, sometimes between the
•oesophagus t>nd trachea to the upper border of the first rib, whence it follows its ordinary course.
In very rare instances this vessel arises from the thoracic aorta, as low down as the fourth
thoracic vertebra. Occasionally it perforates the Scalenus anticus muscle; more rarely it passes
in front of that muscle. Sometimes the subclavian vein passes with the artery behind the
Scalenus anticus muscle. The artery may ascend as high as an inch and a half above the
clavicle or any intermediate point between this and the upper border of the bone, the right
subclavian usually ascending higher than the left.
The left subclavian is occasionally joined at its origin with the left carotid.
Surface Marking. — The course of the subclavian artery in the neck may be mapped out
by describing a curve, with its convexity upward at the base of the posterior triangle. The inner
end of this curve corresponds to the sterno-clavicular joint, the outer end of the centre of the
lower border of the clavicle. The curve is to be drawn with such an amount of convexity that
its mid-point reaches half an inch above the upper border of the clavicle. The left subclavian
artery is more deeply placed than the right in the first part of its course, and, as a rule, does not
reach quite as high a level in the neck. It should be borne in mind that the posterior border of
the Sterno-mastoid muscle corresponds to the outer border of the Scalenus anticus muscle, so
that the third portion of the artery, that part most accessible for operation, lies immediately
external to the posterior border of the Sterno-mastoid muscle.
Surgical Anatomy. — The relations of the subclavian arteries of the two sides having been
examined, the student should direct his attention to a consideration of the best position in which
compression of the vessel may be effected, or in what situation a ligature may be best applied in
cases of aneurism or wound.
Compression of the .subclavian artery is required in cases of operations about the shoulder,
in the axilla, or at the upper part of the arm; and the student will observe that there is only
one situation in which it can be effectually applied — viz., where the artery passes across the
upper surface of the first rib. In order to compress the vessel in this situation, the shoulder
should be depressed, and the surgeon, grasping the side of the neck, should press with his thumb
in the angle formed by the posterior border of the Sterno-mastoid with the upper border of
the clavicle, downward, backward, and inward against the rib; if from any cause the shoulder
cannot be sufficiently depressed, pressure may be made from before backward, so as to compress
the artery against the Scalenus medius muscle and the transverse process of the seventh cervical
vertebra. In appropriate cases, a preliminary incision may be made through the cervical
fascia, and the finger may be pressed down directly upon the artery.
Ligature of the subclavian artery may be required in cases of wounds or of aneurism in
the axilla, or in cases of aneurism on the cardiac side of the point of ligature; and the third part
of the artery is that which is most favorable for an operation, on account of its being compara-
tively superficial and most remote from the origin of the large branches. In those cases where
the clavicle is not displaced, this operation may be performed with comparative facility; but
where the clavicle is pushed up by a large aneurismal tumor in the axilla the artery is placed at
a great depth from the surface, which materially increases the difficulty of the operation. Under
these circumstances it becomes a matter of importance to consider the height to which this
vessel reaches above the bone. In ordinary cases its arch is about half an inch above the clavicle,
occasionally it is as high as an inch and a half, and sometimes so low as to be on a level with
the upper border of the clavicle. If the clavicle is displaced, these variations will necessarily
make the operation more or less difficult according as the vessel is more or less accessible.
The chief points in the operation of tying the third portion of the subclavian artery are as
follows: The patient being placed on a table in the supine position, with the head drawn over to
the opposite side and the shoulder depressed as much as possible, the integument should be
drawn downward over the clavicle, and an incision made through it, upon that bone, from the
anterior border of the Trapezius to the posterior border of the Sterno-mastoid, to which may be
added a short vertical incision meeting the inner end of the preceding. The object in drawing
the skin downward is to avoid any risk of wounding the external jugular vein, for as it perforates
the deep fascia above the clavicle, it cannot be drawn downward with the skin. The soft parts
should now be allowed to glide up, and the cervical fascia should be divided upon a director,
and if the interval between the Trapezius and Sterno-mastoid muscles be insufficient for the per-
formance of the operation, a portion of one or both may be divided. The external jugular vein
will now be seen toward the inner side of the wound: this and the suprascapular and transverse
cervical veins, which terminate in it, should be held aside. If the external jugular vein is at all
in the way and exposed to injury, it should be tied in two places and divided. The suprascapu-
lar artery should be avoided, and the Omo-hyoid muscle held aside if necessary. In the space
beneath this muscle careful search must be made for the vessel : a deep layer of fascia and some
connective tissue having been divided carefully, the outer margin of the Scalenus anticus muscle
must be felt for, and, the finger being guided by it to the first rib, the pulsation of the subcla-
vian artery will be felt as it passes over the rib. The sheath of the vessels having been opened,
the aneurism needle may then be passed around the artery from above downward and inward, so
as to avoid including any of the branches of the brachial plexus. If the clavicle is so raised by
638 THE BLOOD-VASCULAR SYSTEM
the tumor that the application of the ligature cannot be effected in this situation, the artery may
be tied above the first rib, or even behind the Scalenus anticus muscle; the difficulties of the <
operation in such a case will be materially increased, on account of the greater depth of the artery
and the alteration in position of the surrounding parts.
The second part of the subclavian artery, from being that portion which rises highest in
the neck, has been considered favorable for the application of the ligature when it is difficult to
tie the artery in the third part of its course. There are, however, many objections to the opera-
tion in this situation. It is necessary to divide the Scalenus anticus muscle, upon which lies
the phrenic nerve, and at the inner side of which is situated the internal jugular vein; and a
wound of either of these structures might lead to the most dangerous consequences. Again,
the artery is in contact, below, with the pleura, which must also be avoided; and, lastly, .the
proximity of so many of its large branches arising internal to this point must be a still further
objection to the operation. In cases, however, where the sac of an axillary aneurism encroaches
on the neck, it may be necessary to divide the outer half or two-thirds of the Scalenus anticus
muscle, so as to place the ligature on the vessel at a greater distance from the sac. The opera-
tion is performed exactly in the same way as a ligature of the third portion, until the Scalenus
anticus is exposed, when it is to be divided on a director (never to a greater extent than its outer
two-thirds), and it immediately retracts. The operation is therefore merely an extension of
ligature of the third portion of the vessel.
In those cases of aneurism of the axillary or subclavian artery in which the aneurism
encroaches upon the outer portion of the Scalenus muscle to such an extent that a ligature
cannot be applied in that situation, it may be deemed advisable, as a last resource, to tie the
first portion of the subclavian artery. On the left side this operation has been regarded as
almost impracticable; the great depth of the artery from the surface, its intimate relation
with the pleura, and its close proximity to the thoracic duct and to so many important veins
and nerves, present a series of difficulties which it is very difficult to overcome. Nevertheless,
Professor Halsted and Schumpert have each tied successfully the first portion of the left sub-
clavian for aneurism. J. K. Rodgers, of New York, also did it successfully. On the right
side the operation is practicable, and has been performed. Dr. Nassau, of Philadelphia, suc-
cessfully ligated the first part of the right subclavian. The main objection to the operation
in this situation is the smallness of the interval which usually exists between the com-
mencement of the vessel and the origin of the nearest branch. The operation may be per-
formed in the following manner: The patient being placed on the table in the supine position
with the neck extended, an incision should be made along the upper border of the inner part
of the clavicle, and a second along the inner border of the Sterno-mastoid, meeting the
former at an angle. The attachment of both heads of the Sterno-mastoid must be divided
on a director and turned outward; a few small arteries and veins, and occasionally the
anterior jugular vein, must be avoided, or, if necessary, ligatured in two places and divided,
and the Sterno-hyoid and Sterno-thyroid muscles are to be divided in the same manner as the
preceding muscle. After tearing through the deep fascia with the finger-nail, the internal jugul'ar
vein will be seen crossing the subclavian artery; this should be pressed aside and the artery
secured by passing the needle from below upward, by which the pleura is more effectually
avoided. The exact position of the vagus, the recurrent laryngeal, the phrenic and sympa-
thetic nerves should be remembered, and the ligature should be applied near the origin of the
vertebral, in order to afford as much room as possible for the formation of a coagulum
between the ligature and the orgin of the vessel. It should be remembered that the right sub-
clavian artery is occasionally deeply placed in the first part of its course when it arises from
the left side of the aortic arch, and passes in such cases behind the oesophagus or between it
and the trachea.
Collateral Circulation. — After ligature of the third part of the subclavian artery the col-
lateral circulation is mainly established by three sets of vessels, thus described in a dissection:
"1. A posterior set, consisting of the suprascapular and posterior scapular branches of the
subclavian, anastomosing with the subscapular from the axillary.
" 2. An internal set produced by the connection of the internal mammary on the one hand,
with the superior and long thoracic arteries, and the branches from the subscapular on the other.
" 3. A middle or axillary set, which consisted of a number of small vessels derived from branches
of the subclavian, above, and, passing through the axilla, terminated either in the main trunk
or some of the branches of the axillary below. This last set presented most conspicuously the
peculiar character of the newly formed or, rather, dilated arteries, being excessively tortuous,
and forming a complete plexus.
"The chief agent in the restoration of the axillary artery below the tumor was the subscapular
artery, which communicated most freely with the internal mammary, suprascapular, and pos-
terior scapular branches of the subclavian, from all of which is received so great an influx of
blood as to dilate it to three times its natural size."1
1 Guy's Hospital Reports, vol. i., 1836; case of axillary aneurism, in which Mr. Aston Key had tied the sub-
clavian artery on the outer edge of the Scalenus muscle twelve years previously. — ED. of 15th English edition.
THE SUBCLA VIAN ARTERY 639
Wlicn a ligatuiv is applied to the first part of the sulx-Iavian artery, the collateral circulation
is carried on by — 1, the anastomosis between the superior and inferior thyroid; 2, the anasto-
mosis of the two vertebrals; 3, the anastomosis of the internal mammary with the deep epi-
gastric and the aortic intercostals ; 4, the superior intercostal anastomosing with the aortic inter-
costals; 5, the profunda cervicis anastomosing with the princeps cervicis; 6, the scapular branches
of the thyroid axis anastomosing with the branches of the axillary; and 7, the thoracic branches
of the axillary anastomosing with the aortic intercostals.
Branches. — The branches given off from the subclavian artery are:
Vertebral. Internal mammary.
Thyroid axis. Superior intercostal.
On the left side all four branches generally arise from the first portion of the
vessel; but on the right side, the superior intercostal usually arises from the second
portion of the vessel. On both sides of the body the first three branches arise close
together at the inner margin of the Scalenus anticus; in the majority of cases a
free interval of from half an inch to an inch exists between the commencement of
the artery and the origin of the nearest branch; in a smaller number of cases an
interval of more than an inch exists, but it never exceeds an inch and three-quarters.
In a very few instances the interval has been found to be less than half an inch.
The vertebral artery arises from the upper and posterior part of the subclavian
artery, the internal mammary from the lower part of the artery; the thyroid axis
from in front and the superior intercostal from behind.
The Vertebral Artery (a. vertebralis) (Figs. 401 and 411). is generally the first and
largest branch of the subclavian; it arises from the upper and back part of the
first portion of the vessel, and, passing up-
ward, enters the foramen in the transverse
process of the sixth cervical vertebra,1 and
ascends through the foramina in the trans-
verse processes of all the vertebrae above this.
Above the tipper border of the axis it inclines
outward ami upward to the foramen in the
transverse process of the atlas, through which
it passes; it then winds backward behind its
articular process, runs in a deep groove on
the upper surface of the posterior arch of
this bone (Fig. 16), and, passing beneath the
posterior occipito-atlantal ligament (Figs. 199
and 202), pierces the dura and arachnoid,
and enters the skull through the foramen FlG- 41 ^'SbML^eJ'y68 °f th6
magnum. It then passes forward and up-
ward, inclining from the lateral aspect to the front of the oblongata. It unites in
the middle line with the vessel of the opposite side at the lower border of the pons
to form the basilar artery (Fig. 403).
Relations. — At its origin it is situated behind the internal jugular and vertebral
veins, and is crossed by the inferior thyroid artery: it lies between the Longus
colli and Scalenus anticus muscles, having the thoracic duct in front of it on the
left side. It rests on the transverse process of the seventh cervical vertebra and
the sympathetic nerve. Within the foramina formed by the transverse processes
of the vertebra? it is accompanied by a plexus of nerves from the inferior cervical
ganglion of the sympathetic, and is surrounded by a dense plexus of veins which
unite to form the vertebral vein at the lower part of the neck. It is situated in
front of the cervical nerves, as they issue from the intervertebral foramina. While
1 The vertebral artery sometimes enters the foramen in the transverse process of the fifth vertebra. Dr.
myth, who tied this artery in the living subject, founj "'
in the seventh vertebra. — ED. of 15th English edition.
640 THE BLOOD-VASCULAR SYSTEM
winding round the articular process of the atlas, it is contained in a triangular
space, the suboccipital triangle, formed by the Rectus capitis posticus major, the
Superior oblique and the Inferior oblique muscles; and at this point is covered
by the Complexus muscle (Fig. 282). The suboccipital nerve here lies between
the artery and the bone. Within the skull, as the artery winds round the oblon-
gata, it is placed between the hypoglossal nerve and the anterior root of the
suboccipital nerve, beneath the first digitation of the ligamentum denticulatum,
and finally ascends between the basilar process of the occipital bone and the
anterior surface of the oblongata.
Branches. — These may be divided into two sets — those given off in the neck
and those within the cranium.
Cervical Branches. Cranial Branches.
Spinal Kami, or Lateral Spinal. Meningeal Ramus, or Posterior Meningeal.
Muscular. Ventral Spinal, or Anterior Spinal.
Dorsal Spinal, or Posterior Spinal.
Postcerebellar, or Posterior Inferior Cere-
bellar.
Bulbar.
The Spinal Kami, or Lateral Spinal Branches (rami spinales], enter the spinal canal
through the intervertebral foramina and divide into two branches. Of these, one
passes along the roots of the nerves to supply the spinal cord and its membranes,
anastomosing with the other arteries of the spinal cord; the other divides into an
ascending and a descending branch, which unite with similar branches from the
artery above and below, so that two lateral anastomotic chains are formed on the
posterior surface of the bodies of the vertebrae near the attachment of the pedicles.
From these anastomotic chains branches are given off to supply the periosteum and
the bodies of the vertebra?, and to communicate with similar branches from the
opposite side; from these communicating branches small branches are given off
which join similar branches above and below, so that a central anastomotic chain
is formed on the posterior surface of the bodies of the vertebrae.
Muscular Branches are given off to the deep muscles of the neck, where the
vertebral artery curves round the articular process of the atlas. They anastomose
with the occipital and with the ascending and deep cervical arteries.
The Meningeal Ramus or Posterior Meningeal (ramus meningeus) is a small
branch given off from the vertebral opposite the foramen magnum. It ramifies
between the bone and dura in the cerebellar fossa?, and supplies the falcula.
The Ventral or Anterior Spinal (a. spinalis ventralis, a. spinalis anterior) is a
small branch which arises near the termination of the vertebral, and, descending
in front of the oblongata, unites with its fellow on the opposite side at about the
level of the foramen magnum. One of these vessels is usually larger than the
other, but occasionally they are about equal in size. The single trunk thus formed
descends on the front of the spinal cord, and is reinforced by a succession of small
branches which enter the spinal canal through the intervertebral foramina; these
branches are derived from the vertebral artery and the ascending cervical branch
of the inferior thyroid artery in the neck; from the intercostal in the thoracic region ;
and from the lumbar, ilio-lumbar, and lateral sacral arteries in the lower part of
the spine. They unite, by means of ascending and descending branches, to form
a single termatic artery, which extends as far as the lower part of the spinal cord.
This vessel is placed in the pia along the anterior median fissure; it supplies that
membrane and the substance of the cord, and sends off branches at its lower part
to be distributed to the cauda, and ends on the central fibrous prolongation of
the cord.
THE S UB CLA VI AN AR TER Y p4 1
The Dorsal or Posterior Spinal (a. spinalis dor sails, a. spinalis posterior] arises
from the vertebral at the side of the oblongata: passing backward to the posterior
aspect of the spinal cord, it descends on each side, lying behind the posterior roots
of the spinal nerves, and is reinforced by a succession of small branches which
enter the spinal canal through the intervertebral foramina, and by which it is con-
tinued to the lower part of the cord and to the cauda. Branches from these vessels
form a free anastomosis round the posterior roots of the spinal nerves, and com-
municate, by means of very tortuous transverse branches, with the vessel of the
opposite side. At its commencement it gives off an ascending branch, which
terminates on the side of the fourth ventricle.
The Postcerebellar or Posterior Inferior Cerebellar Artery (a. postcerebellaris ,
a. cerebelli inferior posterior) (Fig. 403), the largest branch of the vertebral, winds
backward round the upper part of the oblongata, passing between the origin of
the vagus and accessory nerves, over the restis to the under surface of the cere-
bellum, where it divides into two branches — an internal, which is continued back-
ward to the notch between the two hemispheres of the cerebellum; and an external,
which supplies the under surface of the cerebellum as far as its outer border,
where it anastomoses with the medicerebellar and the precerebellar branches
of the basilar artery. Branches from this artery supply the paraplexus of the
fourth ventricle.
The Bulbar Arteries comprise several minute vessels which spring from the
vertebral and its branches and are distributed to the oblongata.
Surgical Anatomy. — The vertebral artery has been tied in several instances : 1 , for wounds
or traumatic aneurism; 2, after ligation of the innominate, either immediately to prevent hem-
orrhage, or later on to arrest bleeding where it has occurred at the seat of ligation; and 3,
in epilepsy. In these latter cases the treatment has been recommended by Dr. Alexander, of
Liverpool, in the hope that by diminishing the supply of blood to the posterior part of the brain
and the spinal cord-a diminution or cessation of the epileptic fits would result. But, on account
of the uncertainty as to what cases, if any, derived benefit from the operation, it has now been
abandoned as a treatment for epilepsy. The operation of ligation of the vertebral is performed
by making an incision along the posterior border of the Sterno-mastoid muscle, just above the
clavicle. The muscle is pulled to the inner side, and the anterior tubercle of the transverse
process of the sixth cervical vertebra is sought for. A deep layer of fascia being now divided,
the interval between the Scalenus anticus and the Longus colli muscles just below their attach-
ment to the tubercle is defined, and the artery and vein are found in the interspace. The vein
is to be drawn to the outer side, and the aneurism needle is passed from without inward. Drs.
Ramskill and Bright have pointed out that severe pain at the back of the head may be symp-
tomatic of disease of the vertebral artery just before it enters the skull. This is explained by
the close connection of the artery with the suboccipital nerve in the groove on the posterior
arch of the atlas. Disease of the same artery has been also said to affect speech, from pressure
on the hypoglossal nerve where it is in relation with the vessel, leading to paralysis of the muscles
of the tongue.
The Basilar Artery (a. basilaris) (Fig. 403), so named from its position at the
base of the skull, is a single trunk formed by the junction of the two vertebral
arteries; it extends from the posterior to the anterior border of the pons, lying in
the median pontine groove, under cover of the arachnoid. It ends by dividing into
the two postcerebral arteries.
Branches. — Its branches are, on each side, the following:
Transverse. Medicerebellar, or Anterior Inferior Cerebellar.
Internal Auditory. Precerebellar, or Superior Cerebellar.
Postcerebral, or Posterior Cerebral,
The Transverse or Pontal Branches (rami ad pontem) supply the substance of
the pons.
The Internal Auditory (a. auditiva interna) accompanies the auditory nerve
into the internal auditory meatus. It supplies the internal ear.
41
642 THE BLOOD-VASCULAR SYSTEM
The Medicerebellar or Anterior Inferior Cerebellar Artery (a. medicerebellaris, a.
cerebelli inferior anterior) passes backward across the peduncle, to be distributed
to the anterior border of the under surface of the cerebellum, anastomosing with
the postcerebellar branch of the vertebral.
The Precerebellar or Superior Cerebellar Artery (a. praecerebellaris, a. cerebelli
superior) on each side arises near the termination of the basilar. It passes outward,
immediately behind the oculomotor nerve, which separates it from the postcere-
bral, winds round the cms, close to the trochlear nerve, and, arriving at the upper
surface of the cerebellum, divides into branches which ramify in the pia and,
reaching the circumference of the cerebellum, anastomose with the branches of the
medicerebellar arteries. Several branches are given to the pineal gland, the valve
of Vieussens, and the velum.
The Postcerebral or Posterior Cerebral Artery (a. postccrebralis, a. cerebri posterior)
(Figs. 403, 405, 406, and 408), on each side, is the terminal branch of the basilar.
It is larger than the preceding, from which it is separated near its origin by the
oculomotor nerve. Passing outward, parallel to the precerebellar artery, and
receiving the postcommunicant from the internal carotid, it winds round the crus,
and passes to the under surface of the occipital lobes of the cerebrum, and break
up into branches for the supply of the temporal and occipital lobes. The branches
of the postcerebral artery are:
Postero-median ganglionic. ( Anterior temporal.
Postchoroid or Posterior choroid. Three terminal < Posterior temporal.
Postero-lateral ganglionic. ( Occipital.
The postero-median ganglionic branches (Fig. 408) are a group of small arteries
which arise at the commencement of the postcerebral artery; these, with simi-
lar branches from the postcommunicant, pierce the postperforatum, and supply
the internal surfaces of the thalamus and the walls of the third ventricle. The
postchoroid enters the interior of the brain beneath the splenium of the callosum,
and supplies the velum and the paraplexus. The postero-lateral ganglionic branches
are a group of small arteries which arise from the postcerebral artery, after it has
turned round the crus; they supply a considerable portion of the thalamus. The
terminal branches are distributed as follows: the first, or the anterior temporal
branches, to the basal surface of the anterior portion of the temporal lobe; the
second, or the posterior temporal branches, to the external surface of the occipital
lobe and the subtemporal convolution; and the third, or the occipital branches,
to the mesal and lateral surfaces of the occipital lobe.
Circulus or Circle of Willis (circulus arteriosus[Willisi]). — The remarkable anas-
tomosis which exists between the branches of the internal carotid and vertebral
arteries at the base of the brain constitutes the circulus. It is formed in front, by the
precerebral arteries, branches of the internal carotid, which are connected together
by the precommunicant; behind, by the two postcerebrals, branches of the basilar,
which are connected on each side with the internal carotid by the postcommunicant
arteries (Fig. 403). It is by this anastomosis that the cerebral circulation is equal-
ized, and provision made for effectually carrying it on if one or more of the branches
are obliterated. The parts of the brain included within this arterial circle are — the
terma, the chiasm, the tuber, the tuber cinereum, the albicans, and the post-
perforatum.
The Thyroid Axis (truncus thyreocermcalis) (Figs. 394 and 413) is a short thick
trunk which arises from the forepart of the first portion of the subclavian artery,
close to the inner border of the Scalenus anticus muscle, and divides, almost
immediately after its origin, into three branches — the inferior thyroid, supra-
scapular, and transversalis colli.
THE SUBCLAVIAN ARTERY
643
The Inferior Thyroid Artery (a. thyreoidea inferior) (Fig. 394) passes upward, in
front of the vertebral artery and Longus colli muscle; then turns inward behind the
sheath of the common carotid artery and internal jugular vein, and also behind
the sympathetic nerve, the middle cervical ganglion resting upon the vessel, and
reaching the lower border of the lateral lobe of the thyroid gland it divides into
two branches, which supply the posterior and under part of the organ, and anasto-
mose in its substance with the superior thyroid and with the corresponding artery
of the opposite side. (See page 605.) The recurrent laryngeal nerve passes upward,
generally behind but occasionally in front of the artery. Its branches are:
Inferior Laryngeal. (Esophageal.
Tracheal. Ascending Cervical.
Muscular.
The inferior laryngeal branch (a. laryngea inferior] ascends upon the trachea
to the back part of the larynx, in company with the recurrent laryngeal nerve,
and supplies the muscles and mucous membrane of this part, anastomosing with
the laryngeal branch from the superior thyroid artery and with the inferior laryn-
geal branch from the opposite side. The tracheal branches (rami tracheales) are
distributed upon the trachea, anastomosing below with the bronchial arteries.
The oesophageal branches (rami oesophagei) are distributed to the oesophagus,
and anastomose with the rcsophageal branches of the aorta. The ascending
cervical (a. cervicalis ascendens) is a small branch which arises from the inferior
thyroid just where that vessel is passing behind the common carotid artery, and
runs up on the anterior tubercles of the transverse processes of the cervical
vertebrae in the interval between the Scalenus anticus and Rectus capitis anticus
major muscles. It gives muscular branches (rami musculares) to the muscles of
the neck, which anastomose with branches of the vertebral, and sends one or two
branches (rami spinales) into the spinal canal through the intervertebral foramina
to be distributed to the spinal cord and its membranes, and to the bodies of the
vertebrae in the same manner as the lateral spinal branches from the vertebral.
It anastomoses with the ascending pharyngeal and occipital arteries. The mus-
cular branches supply the depressors of the hyoid bone, the Longus colli, the
Scalenus anticus, and the Inferior constrictor of the pharynx. One of the mus-
cular branches passes between the transverse processes of the fourth and fifth
cervical vertebrae and reaches the deep muscles of the neck. It is called the
ramus profundus.
Surgical Anatomy. — The inferior thyroid artery has been tied, in conjunction with the
superior thyroid, in cases of bronchocele. An incision is made along the anterior border of the
Sterno-mastoid down to the clavicle. After the deep fascia has been divided, the Sterno-mas-
toid and carotid vessels are drawn outward and the carotid tubercle (Chassaignac's tubercle)
sought for. The vessel will be found just below this tubercle, between the carotid sheath on the
outer side of the trachea and oesophagus on the inner side. In passing the ligature great care
must be exercised to avoid including the recurrent laryngeal nerve, which is occasionally found
crossing in front of the vessel. Before extirpating a goitrous lobe of the thyroid the superior
and inferior thyroid arteries of the diseased side are to be ligated.
The Suprascapular or Transversalis Humeri Artery (a. transversa scapula} (Figs. 394
and 412), smaller than the tranversalis colli, passes obliquely from within outward,
across the root of the neck. It at first passes downward and outward across the
Scalenus anticus muscle and phrenic nerve, being covered by the Sterno-mastoid;
it then crosses the subclavian artery and the cords of the brachial plexus, and runs
outward, behind and parallel with the clavicle and Subclavius muscle, and beneath
the posterior belly of the Omo-hyoid, to the superior border of the scapula, where
it passes over the transverse ligament of the scapula, which separates it from the
suprascapular nerve, and reaches the supraspinous fossa. In this situation it lies
close to the bone, and ramifies between it and the Supraspinatus muscle, to which it
644 THE BLOOD -VASCULAR SYSTEM
supplies branches. It then passes downward behind the neck of the scapula, to
reach the infraspinous fossa, where it anastomoses with the dorsalis scapulse branch
of the subscapular artery and branches of the posterior scapular arteries. Besides
distributing branches to the Sterno-mastoid, Subclavius, and neighboring muscles,
it gives off a suprasternal branch, which crosses over the sternal end of the clavicle to
the skin of the upper part of the chest; and a supra-acromial branch (ramus acro-
mialis), which, piercing the Trapezius muscle, supplies the skin over the acromion,
anastomosing with the acromial thoracic artery. As the artery passes over the trans-
verse ligament of the scapula, a branch descends into the subscapular fossa,
ramifies beneath the subscapular muscle, and anastomoses with the posterior and
subscapular arteries. The suprascapular artery also sends branches to the
acromio-clavicular and shoulder joints, and a nutrient artery to the clavicle.
Posterior scapular.
Suprascapular. Acromiai branch
o/ Thoracico-acromialis.
Anterior
circumflex.
ermination of
subscapular.
FIG. 412. — The scapular and circumflex arteries.
The Transverse Cervical or Transversalis Colli Artery (a. transversa colli) (Fig. 394)
passes transversely outward, across the upper part of the subclavian triangle, to
the anterior margin of the Trapezius muscle, beneath which it divides into two
branches, the superficial cervical and the posterior scapular. In its passage across
the neck it crosses in front of the phrenic nerve, Scaleni muscles, and the brachial
plexus, between the divisions of which it sometimes passes, and is covered by the
Platysma, Sterno-mastoid, Omo-hyoid, and Trapezius muscles. The superficial
cervical (ramus ascendens) ascends beneath the anterior margin of the Trapezius,
distributing branches to it and to the neighboring muscles and glands in the neck,
and anastomosing with the superficial branch of the arteria princeps cervicis. The
posterior scapular (ramus descendens) (Fig. 412) passes beneath the Levator anguli
scapulae muscle to the superior angle of the scapula, and then descends along the
posterior border of that bone as far as the inferior angle. In its course it is
covered by the Rhomboid muscles, supplying them and the Latissimus dorsi and
Trapezius, and anastomosing with the suprascapular and subscapular arteries,
and with the posterior branches of some of the intercostal arteries.
Peculiarities. — The superficial cervical frequently arises as a separate branch from the thyroid
axis; and the posterior scapular, from the third, more rarely from the second, part of the sub-
clavian.
THE SUBCLAV1AN ARTERY
645
The Internal Mammary (a. mammaria interna) (Fig. 413) arises from the
under surface of the first portion of the subclavian artery, opposite the thyroid
Scalenus
mil it-nit. _
Anterior intercostal
branches.
Musculo-
phrenic
Thyroid axis.
Common carotid.
Innominate.
^-Internal mam-
mary.
Perforating
branches.
-Superior epi-
gastric.
—Deep epi-
gastric.
•External
iliac.
FIG. 413. — The internal mammary artery and its branches.
axis. It passes downward and inward behind the costal cartilage of the first rib
to the inner surface of the anterior wall of the chest, resting against the costal
cartilages about half an inch from the margin of the sternum ; and, at the interval
646 THE BLOOD -VASCULAR SYSTEM
between the sixth and seventh cartilages, divides into two branches, the musculo-
phrenic and superior epigastric.
Relations.— At its origin it is covered by the internal jugular and subclavian
veins, and as it enters the thorax is crossed from without inward by the phrenic
nerve, and then passes forward close to the outer side of the innominate vein. In
the upper part of the thorax it lies behind the costal cartilages and Internal inter-
costal muscles, and is crossed by the terminations of the upper six intercostal
nerves. At first it lies upon the pleura, but at the lower part of the thorax the
Triangularis sterni separates the artery from this membrane. It has two venae
comites; these unite into a single vein, which joins the innominate vein of its own
side.
Branches. — The branches of the internal mammary are —
Comes Nervi Phrenici (Superior Phrenic). Anterior Intercostal.
Mediastinal. Perforating.
Pericardiac. Musculo-phrenic.
Sternal. Superior Epigastric.
The Comes Nervi Phrenici or Superior Phrenic (a. pericardiacophrenica} is a long
slender branch which accompanies the phrenic nerve, between the pleura and
pericardium, to the Diaphragm. It gives branches to the pericardium and is
distributed upon the Diaphragm, anastomosing with the other phrenic branches
from the internal mammary and with phrenic branches of the abdominal aorta.
The Mediastinal Branches (aa. mediastinales anteriores) are small vessels
which are distributed to the areolar tissue and lymphatic glands in the anterior
mediastinum and to the remains of the thymus gland.
The Pericardiac Branches supply the upper part of the anterior surface of the
pericardium, the lower part receiving branches from the musculo-phrenic artery.
The Sternal Branches (rami sternales) are distributed to the Triangularis sterni
and to the posterior surface of the sternum.
The inediastinal, pericardiac, and sternal branches, together with some twigs
from the comes nervi phrenici, anastomose with branches from the intercostal and
bronchial arteries, and form a minute plexus beneath the pleura, which has been
named by Turner the subpleural mediastinal plexus.
The Anterior Intercostal Arteries (rami intercostales] supply the five or six upper
intercostal spaces. The branch corresponding to each space soon divides into
two, or the two branches may come off separately from the parent trunk. The
small vessels pass outward in the intercostal spaces, one, the larger, lying near
the lower margin of the rib above, and the other, the smaller, near the upper
margin of the rib below, and anastomose with the intercostal arteries from the
aorta. They are at first situated between the pleura and the Internal intercostal
muscles, and then between the Internal and External intercostal muscles. They
supply the Intercostal muscles, and, by branches which perforate the External
intercostal muscle, reach the Pectoral muscles and the mammary gland.
The Perforating or Anterior Perforating Arteries (rami perforantes) correspond
to the five or six upper intercostal spaces. They arise trom the internal mam-
mary, pass forward through the intercostal spaces, and, curving outward, supply
the Pectoralis major and the integument. Those which correspond to the second,
third, and fourth spaces are distributed to the mammary gland. In females,
during lactation, these branches are of large size.
The Musculo-phrenic Artery (a. musculophrenica) is directed obliquely down-
ward and outward, behind the cartilages of the false ribs, perforating the Dia-
phragm at the eighth or ninth rib, and terminating, considerably reduced in size,
opposite the last intercostal space. It gives off anterior intercostal arteries to
each of the intercostal spaces across which it passes; these diminish in size as the
SURGICAL ANATOMY OF THE AXILLA 647
spaces decrease in length, and are distributed in a manner precisely similar to
the anterior intercostals from the internal mammary. The musculo-phrenic also
gives branches to the lower part of the pericardium, and others which run back-
ward to the Diaphragm and downward to the abdominal muscles.
The Superior Epigastric (a. epigastrica superior) continues in the original direc-
tion of the internal mammary; it descends through the cellular interval between
the costal and sternal attachments of the Diaphragm, and enters the sheath of the
Rectus abdominis muscle, at first lying behind the muscle, and then perforating
it and supplying it, and anastomosing with the deep epigastric artery from the
external iliac. Some branches perforate the sheath of the Rectus, and supply the
muscles of the abdomen and the integument, and a small branch, which passes
inward upon the side of the ensiform appendix, anastomoses in front of that
cartilage with the superior epigastric artery of the opposite side. It also gives
some twigs to the Diaphragm, while from the artery of the right side small
branches extend into the falciform ligament of the liver and anastomose with
the hepatic artery.
Surgical Anatomy. — The course of the internal mammary artery may be defined by draw-
ing a line across the six upper intercostal spaces half an inch from and parallel with the sternum.
The position of the vessel must be remembered, as it is liable to be wounded in stabs of the
chest-wall. It is most easily reached by a transverse incision in the second intercostal space.
The Superior Intercostal (truncus costocervicalis)(¥igs. 401 and 419) arises from
the upper and back part of the siibclavian artery, behind the Scalenus anticus mus-
cle on the right side and to the inner side of that muscle on the left side. Passing
backward, it gives off the deep cervical branch, and then descends behind the
pleura in front of the necks of the first two ribs, and inosculates with the first
aortic intercostal. As it crosses the neck of the first rib it lies to the inner side
of the anterior division of the first thoracic nerve and to the outer side of the first
thoracic ganglion of the sympathetic. In the first intercostal space it gives off a
branch which is distributed in a manner similar to the distribution of the aortic
intercostals. The branch for the second intercostal space usually joins with one
from the highest aortic intercostal. Each intercostal gives off a branch to the
posterior spinal muscles, and a small branch which passes through the corre-
sponding intervertebral foramen to the spinal cord and its membranes.
The Deep Cervical Branch (a. cervicalis profunda) arises, in most cases, from
the superior intercostal, and is analogous to the posterior branch of an aortic
intercostal artery; occasionally it arises as a separate branch from the sub-
clavian artery. Passing backward, above the eighth cervical nerve and between
the transverse process of the seventh cervical vertebra and the first rib, it runs
up the back part of the neck, between the Complexus and Semispinalis colli
muscles, as high as the axis vertebra, supplying these and adjacent muscles, and
anastomosing with the deep branch of the arteria princeps cervicis of the occipital,
and with branches which pass outward from the vertebral. It gives off a special
branch which enters the spinal canal through the intervertebral foramen between
the seventh cervical and first thoracic vertebrae.
SURGICAL ANATOMY OF THE AXILLA.
The axilla is a pyramidal space, situated between the upper and lateral part
of the chest and the inner side of the arm.
Boundaries. — Its apex, which is directed upward toward the root of the neck,
corresponds to the interval between the first rib, the upper edge of the scapula,
and the clavicle, through which the axillary vessels, the brachial plexus of nerves,
and the long thoracic nerve pass. This interval is the cervico -axillary passage.
648 THE BLOOD -VASCULAR SYSTEM
The base, directed downward, is formed by the integument and a thick layer of
fascia, the axillary fascia (fascia axillaris) (Fig. 312), extending between the lower
border of the Pectoralis major in front and the lower border of the Latissimus
dorsi behind (page 465). The axillary fascia is perforated at several points.
The large central opening is called the foramen of Langer. The inner margin of
the foramen of Langer is dense and constitutes a part of the axillary arch,
which is a fibro-muscular slip derived from the latissimus dorsi. The axilla
is broad internally at the chest, but narrow and pointed externally at the
arm. The anterior boundary is formed by the Pectoralis major and minor mus-
cles, the former covering the whole of the anterior wall of the axilla, the latter
covering only its central part, the costo-coracoid membrane, the clavicle, and the
Subclavius muscle. The posterior boundary, which extends somewhat lower
than the anterior, is formed by the Subscapularis above, the Teres major and
Latissimus dorsi below. On the inner side are the first four ribs with their
corresponding Intercostal muscles, and part of the Serratus rnagnus. On
the outer side, where the anterior and posterior boundaries converge, the space
is narrow, and bounded by the humerus, the Coraco-brachialis and Biceps
muscles.
Contents. — This space contains the axillary vessels and brachial plexus of
nerves, with their branches, some branches of the intercostal nerves, and a large
number of lymphatic glands, all connected together by a quantity of fat and loose
areolar tissue.
Position of the Contents. — The axillary artery and vein, with the brachial plexus
of nerves, extend obliquely along the outer boundary of the axillary space, from
its apex to its base, and are placed much nearer the anterior than the posterior wall,
the vein lying to the inner or thoracic side of the artery and partially concealing
it. At the forepart of the axillary space, in contact with the Pectoral muscles, and
along the anterior margin are the thoracic branches of the axillary artery, and
along the lower margin of the Pectoralis minor the long thoracic artery extends
to the side of the chest. At the back part, in contact with the lower margin of
the Subscapularis muscle, are the subscapular vessels and nerves; winding around
the outer border of this muscle is the dorsalis scapulae artery and veins; and, close
to the neck of the humerus, the posterior circumflex vessels and the circumflex
nerve are seen curving backward to the shoulder.
Along the inner or thoracic side no vessel of any importance exists, the upper
part of the space being crossed merely by a few small branches from the superior
thoracic artery. There are some important nerves, however, in this situation —
viz., the long thoracic or external respiratory nerve, descending on the surface
of the Serratus magnus, to which it is distributed; and perforating the upper
and anterior part of this wall, the intercosto-humeral nerve or nerves, passing
across the axilla to the inner side of the arm.
The cavity of the axilla is filled by a quantity of loose areolar tissue and a large
number of small arteries and veins, all of which are, however, of inconsiderable
size, and numerous lymphatic glands, the position and arrangement of which are
described on a subsequent page.
Surgical Anatomy. — The axilla is a space of considerable surgical importance. It trans-
mits the large vessels and nerves to the upper extremity, and these may be the seat of injury or
disease: it contains numerous lymphatic glands which may require removal when diseased; in it
is 'a quantity of loose connective and adipose tissue which may be readily infiltrated with blood
or pus. The axilla may be the seat of rapidly growing tumors. Moreover, it is covered at its
base by thin skin, largely supplied with sebaceous and sweat glands, which is frequently the
seat of small cutaneous abscesses and boils, and of eruptions due to irritation.
In suppuration in the axilla the arrangement of the fasciae plays a very important part in the
direction which the pus takes. As described on page 466, the costo-coracoid membrane, after
covering in the space between the clavicle and the upper border of the Pectoralis minor, splits
THE AXILLARY ARTERY
649
to enclose this muscle, and, reblending at its lower border, becomes incorporated with the axillary
fascia at the anterior fold of the axilla. This is known as the dam-pectoral fascia. Suppura-
tion may take place either superficial to or beneath this layer of fascia; that is, either between
the Pectorals or below the Pectoralis minor: in the former case, the pus would point either at the
anterior border of the axillary fold or in the groove between the Deltoid and the Pectoralis major;
in the latter, the pus would have a tendency to surround the vessels and nerves and ascend into
the neck, that being the direction in which there is least resistance. Its progress toward the
skin is prevented by the axillary fascia; its progress backward, by the Serratus magnus; forward,
by the clavi-pectoral fascia; inward, by the wall of the thorax; and outward, by the upper limb.
The pus in these cases, after extending into the neck, has been known to spread through the
superior opening of the thorax into the mediastinum.
In opening an axillary abscess the knife should be entered in the floor of the axilla, midway
between the anterior and posterior margins and near the thoracic side of the space. It is well
to use a director and dressing forceps after an incision has been made through the skin and fascia
in the manner directed by the late Mr. Hilton.
The student should attentively consider the relation of the vessels and nerves in the several
parts of the axilla, for it is the universal plan, at the present day, to remove the glands from
the axilla in operating for cancer of the breast. In performing such an operation it will be
necessary to proceed with much caution in the direction of the outer wall and apex of the space,
Anterior
circumflex.
FIG. 414. — The axillary artery and its branches.
as here the axillary vessels will be in danger of being wounded. Toward the posterior wall it
will be necessary to avoid the subscapular, dorsalis scapulae, and posterior circumflex vessels.
Along the anterior wall it will be necessary to avoid the thoracic branches. In clearing out the
axilla the axillary vein should be first defined and cleared up to the apex of the axilla.
When the apex of the space is reached, all fat and glands must be carefully removed and the
whole axilla cleared by separating the tissues along the inner and posterior walls, so that when
the proceeding is completed, the axilla is cleared of all its contents except the main vessels and
nerves.
THE AXILLARY ARTERY (A. AXILLARIS) (Fig. 414).
The axillary artery, the continuation of the subclavian, commences at the
outer border of the first rib, and terminates at the lower border of the tendon
650 THE BLOOD -VASCULAR SYSTEM
of the Teres major muscle, where it takes the name of brachial. Its direction
varies with the position of the limb: when the arm lies by the side of the
chest, the vessel forms a gentle curve, the convexity being upward and outward ;
when the arm is directed at right angles with the trunk, the vessel is nearly
straight; and when the arm is elevated still higher, the arteries describe a curve
the concavity of which is directed upward. At its commencement the artery is
very deeply situated, but near its termination it is superficial, being covered only
by the skin and fascia. The description of the relations of this vessel is facili-
tated by its division into three portions, the first portion being above the
Pectoralis minor; the second portion behind; and the third below that muscle.
Relations. — The first portion of the axillary artery is in relation, in front, with
the clavicular portion of the Pectoralis major, the costo-coracoid membrane, the
external anterior thoracic nerve, and the acromio-thoracic and cephalic veins;
behind, with the first intercostal space, the corresponding Intercostal muscle,
the second and a portion of the third digitation of the Serratus magnus, and the
long thoracic and internal anterior thoracic nerves; on its outer side, with the
brachial plexus, from which it is separated by a little cellular interval; on its inner
or thoracic side, with the axillary vein, which overlaps the artery.
RELATIONS OF THE FIRST PORTION OF THE AXILLARY ARTERY.
In front.
Pectoralis major.
Costo-coracoid membrane.
External anterior thoracic nerve.
Acromio-thoracic and cephalic veins.
Outer side. I Axillary \ Inner side.
Arterv
Brachial plexus. I First portion. I Axillary vein.
Behind.
First Intercostal space and Intercostal muscle.
Second and third digitations of Serratus magnus.
Long thoracic and Internal anterior thoracic nerves.
The second portion of the axillary artery lies beyond the Pectoralis minor. It
is covered, in front, by the Pectoralis major and minor muscles; behind, it is
separated from the Subscapularis by a cellular interval; on the inner side is the
axillary vein, separated from the artery by the inner cord of the plexus and the
internal anterior thoracic nerve. The brachial plexus of nerves surrounds the
artery on three sides, and separates it from direct contact with the vein and
adjacent muscles.
RELATIONS OF THE SECOND PORTION OF THE AXILLARY ARTERY.
In front.
Pectoralis major and minor.
Outer side. / \ Inner side.
... f Axillary \
Outer cord or plexus. [ Artery. | Axillary vein.
Inner cord of plexus.
Internal anterior thoracic nerve.
/-
Behind.
Subscapularis.
Posterior cord of plexus.
THE AXILLARY ARTERY 651
The third portion of the axillary artery lies below the Pectoralis minor. It is
in relation, in front, with the lower part of the Pectoralis major above, being
covnrd only by the integument and fascia below, where it is crossed by the inner
head of the median nerve; behind, with the lower part of the Subscapularis and
the tendons of the Latissimus dorsi and Teres major; on its outer side, with the
( loraco-brachialis; on its inner or thoracic side, with the axillary vein. The nerves
of the brachial plexus bear the following relation to the artery in this part of its
course: on the outer side is the median nerve, and the musculo-cutaneous for a
short distance; on the inner side, the ulnar nerve (between the vein and artery)
and the lesser internal cutaneous nerve (to the inner side of the vein); in front
is the internal cutaneous nerve, and behind, the musculo-spiral and circumflex, the
latter extending only to the lower border of the Subscapularis muscle.
RELATIONS OF THE THIRD PORTION OF THE AXILLARY ARTERY.
In front.
Integument and fascia.
Pectoralis major.
Inner head of median nerve.
Internal cutaneous nerve.
Outer side. f \ Inner side.
Coraco-brachialis. i ^Lery. \ Ulnar nerve.
Median nerve. I Third portion, y Axillary vein.
Musculo-cutaneous nerve. V / Lesser internal cutaneous nerve.
Behind.
Subscapularis.
Tendons of Latissimus dorsi and Teres major.
Musculo-spiral and circumflex nerves.
Peculiarities. — The axillary artery, in about one case out of every ten, gives off a large
branch, which forms either one of the arteries of the forearm or a large muscular trunk. In the
first set of cases this artery is most frequently the radial (1 in 33), sometimes the ulnar (1 in 72),
and, very rarely, the interosseous (1 in 506). In the second set of cases the trunk has been
found to give origin to the subscapular, circumflex, and profunda arteries of the arm. Some-
times only one of the circumflex, or one of the profunda arteries, arose from the trunk. In
these cases the brachial plexus surrounded the trunk of the branches and not the main vessel.
Surface Marking. — The course of the axillary artery may be marked out by raising the
arm to a right angle with the body and drawing a line from the middle of the clavicle to the
point where the tendon of the Pectoralis major crosses the prominence caused by the Coraco-
brachialis as it emerges from under cover of the anterior fold of the axilla. The third portion
of the artery can be felt pulsating beneath the skin and fascia, at the junction of the anterior
with the middle third of the space between the anterior and posterior folds of the axilla, close to
the inner border of the Coraco-brachialis muscle.
Surgical Anatomy. — The student, having carefully examined the relations of the axillary
artery in its various parts, should now consider in what situation compression of this vessel
may be most easily effected, and the best position for the application of a ligature to it when
necessary.
Compression of the vessel may be required in the removal of tumors or in amputation of
the upper part of the arm; and the only situation in which this can be effectually made is in the
lower part of its course; by pressing on it in this situation from within outward against the
humerus the circulation may be effectually arrested.
The axillary artery is perhaps more frequently lacerated than any other artery in the body,
with the exception of the popliteal, by violent movements of the extremity, especially in those
cases where its coats are diseased. It has occasionally been ruptured in attempts to reduce old
dislocations of the shoulder-joint. This accident is most likely to occur during the preliminary
breaking down of adhesions, in consequence of the artery having become fixed to the capsule
of the joint. Aneurism of the axillary artery is of frequent occurrence, a large percentage of
the cases being traumatic in their origin, due to the violence to which the vessel is exposed in
the varied, extensive, and often violent movements of the limb.
The (tpi>hration of a ligature to the axillary artery may be required in cases of
aneurism of the upper part of the brachial or as a distal operation for aneurism of the sub-
652 THE BLOOD -VASCULAR SYSTEM
clavian; and there are only two situations in which the vessel can be secured — viz., in the first
and in the third parts of its course; for the axillary artery at its central part is so deeply seated,
and, at the same time, so closely surrounded with large nerve trunks, that the application of a
ligature to it in that situation would be almost impracticable.
In the third part of its course the operation is most simple, and may be performed in the
following manner: The patient being placed on a bed and the arm separated from the side, with
the hand supinated, an incision about two inches in length is made through the integument
forming the floor of the axilla, the cut being a little nearer to the anterior than the posterior
fold of the axilla. After carefully dissecting through the areolar tissue and fascia, the median
nerve and axillary vein are exposed; the former having been displaced to the outer and the
latter to the inner side of the arm, the elbow being at the same time bent, so as to relax the
structures and facilitate their separation, the ligature may be passed round the artery from the
ulnar to the radial side.
This portion of the artery is occasionally crossed by a muscular slip, the axillary arch, derived
from the Latissimus dorsi, which may mislead the surgeon during an operation. The occasional
existence of this muscular fasciculus was spoken of in the description of the muscles. It may
easily be recognized by the transverse direction of its fibres.
The first portion of the axillary artery may be tied in cases of aneurism encroaching so far
upward that a ligature cannot be applied in the lower part of its course. Notwithstanding that
this operation has been performed in some few cases, and with success, its performance is at-
tended with much difficulty and danger. The student will remark that in this situation it would
be necessary to divide a thick muscle, and, after incising the costo-coracoid membrane, the
artery would be exposed at the bottom of a more or less deep space, with the cephalic and axil-
lary veins in such relation with it as must render the application of a ligature to this part of
the vessel particularly hazardous. Under such circumstances it is an easier, and at the same
time more advisable, operation to tie the subclavian artery in the third part of its course.
The vessel in the first part of its course can best be secured through a curved incision the
convexity of which is downward. This incision passes from a point half an inch external to
the sterno-clavicular joint to a point half an inch internal to the coracoid process. The limb
is to be well abducted and the head inclined to the opposite side, and this incision is carried
through the superficial structures, care being taken to avoid the cephalic vein at the outer angle
of the incision. The clavicular origin of the Pectoralis major is then divided in the whole
extent of the wound. The arm is now to be brought to the side, and the upper edge of the
Pectoralis minor defined and drawn downward. The costo-coracoid membrane is to be care-
fully divided close to the coracoid process, and the axillary sheath exposed ; this is to be opened
with especial care on account of the vein overlapping the artery. The needle should be passed
from below, so as to avoid wounding the vein.
In a case of wound of the vessel the general practice of cutting down upon and tying it above
and below the wounded point should be adopted in all cases.
Collateral Circulation after Ligature of the Axillary Artery.— If the artery be tied
above the origin of the acromial thoracic, the collateral circulation will be carried on bv the same
branches as after the ligature of the subclavian; if at a lower point, between the acromial thoracic
and subscapular arteries, the latter vessel, by its free anastomoses with the other scapular arteries,
branches of the subclavian, will become the chief agent in carrying on the circulation, to which
the long thoracic, if it be below the ligature, will materially contribute by its anastomoses with
the intercostal and internal mammary arteries. If the point included in the ligature be below
the origin of the subscapular artery, it will most probably also be below the origins of the cir-
cumflex arteries. The chief agents in restoring the circulation will then be the subscapular and
the two circumflex arteries anastomosing with the superior profunda from the brachial, which
will be afterward referred to as performing the same office after ligation of the brachial. The
cases in which the operation has been performed are few in number, and no published account
of dissections of the collateral circulation appears to exist.
Branches. — The branches of the axillary artery are —
p * , f Superior Thoracic. ^ , , f Long Thoracic.
r rom first part < . ' . , —,, f rom second part \ A , & r™
( Acromial 1 horacic. ( Alar 1 horacic.
C Subscapular.
From third part < Posterior Circumflex.
' Anterior Circumflex.
The Superior Thoracic (a. thoracalis supremo) is a small artery which arises
from the axillary separately or by a common trunk with the acromial thoracic.
Running forward and inward along the upper border of the Pectoralis minor, it
THE AXILLARY ARTERY 653
passes between it and the Pectoralis major to the side of the chest. It supplies
thrse muscles and the parietes of the thorax, anastomosing with the internal mam-
mary and intercostal arteries.
The Acromial Thoracic or the Thoracic Axis (a. thoracoacromialis) is a
short trunk which arises from the forepart of the axillary artery, its origin being
generally overlapped by the upper edge of the Pectoralis minor. Projecting
forward to the upper border of the Pectoralis minor, it divides into four sets of
branches — thoracic, acromial, descending, and clavicular.
The Thoracic Branches (rami pectorales), two or three in number, are distributed
to the Serratus magnus and Pectoral muscles, anastomosing with the intercostal
branches of the internal mammary.
The Acromial Branch (ramus acromialis) is directed outward toward the acro-
mion, supplying the Deltoid muscle, and anastomosing, on the surface of the
acromion, with the suprascapular and posterior circumflex arteries.
The Descending or Humeral Branch (ramus deltoideus) passes in the space between
the Pectoralis major and Deltoid, in the same groove as the cephalic vein, and
supplies both muscles.
The Clavicular Branch (ramus clavicularis) , which is very small, passes upward
to the Subclavius muscle.
The Long Thoracic or the External Mammary (a. thoracalis lateralis) passes
downward and inward along the lower border of the Pectoralis minor to the side
of the chest, supplying the Serratus magnus, the Pectoral muscles, and mammary
gland, and sending branches across the axilla to the axillary glands and Sub-
scapularis; it anastomoses with the internal mammary and intercostal arteries.
The Alar Thoracic is a small branch which supplies the glands and areolar
tissue of the axilla. Its place is frequently supplied by branches from some of the
other thoracic arteries.
The Subscapular (a. subscapularis), the largest branch of the axillary artery,
arises opposite the lower border of the Subscapularis muscle, and passes downward
and backward along its lower margin to the inferior angle of the scapula, where it
anastomoses with the long thoracic and intercostal arteries and with the posterior
scapular, a branch of the transversalis colli, from the thyroid axis of the sub-
clavian. About an inch and a half from its origin it gives off a large branch, the
dorsalis scapulae, and terminates by supplying branches to the muscles in the
neighborhood.
The Dorsalis Scapulae (a. circumflexa scapulae) is given off from the subscapular
about an inch and a half from its origin, and is generally larger than the continua-
tion of the vessel. It curves round the axillary border of the scapula, leaving the
axilla through the space between the Teres minor above, the Teres major below,
and the long head of the Triceps externally (Fig. 412), and enters the infraspinous
fossa by passing under cover of the Teres minor, where it anastomoses with the
posterior scapular and suprascapular arteries. In its course it gives off two sets
of branches: one enters the subscapular fossa beneath the Subscapularis, which it
supplies, anastomosing with the posterior scapular and suprascapular arteries;
the other is continued along the axillary border of the scapula, between the Teres
major and minor, and, at the dorsal surface of the inferior angle of the bone, anas-
tomoses with the posterior scapular. In addition to these, small branches are
distributed to the back part of the Deltoid muscle and the long head of the
Triceps, anastomosing with an ascending branch of the superior profunda of the
brachial.
The Circumflex Arteries wind round the surgical neck of the humerus. The
posterior circumflex (a. circumflexa humeri posterior) (Fig. 412), the larger of the
two, arises from the back part of the axillary opposite the lower border of the
Subscapularis muscle, and, passing backward with the circumflex veins and nerve
654
THE BLOOD -VASCULAR SYSTEM
through the quadrangular space bounded by the Te'res major and minor, the
scapular head of the Triceps and the humerus, winds round the neck of that bone
and is distributed to the Deltoid muscle and shoulder-joint, anastomosing with the
anterior circumflex and acromial thoracic arteries, and with the superior profunda
branch of the brachial artery. The anterior circumflex (a. circumflexa humeri ante-
rior) (Figs. 412 and 414), considerably smaller than the preceding, arises nearly
opposite that vessel from the outer side of the axillary artery. It passes horizon-
tally outward beneath the Coraco-brachialis and short head of the Biceps, lying
upon the forepart of the neck of the
humerus, and, on reaching the bicipital
groove, gives off an ascending branch
which passes upward along the groove
to supply the head of the bone and the
shoulder-joint. The trunk of the vessel
is then continued outward beneath the
Deltoid, which it supplies, and anasto-
moses with the posterior circumflex
artery.
THE BRACHIAL ARTERY (A. BRA-
CHIALIS) (Fig. 415).
The brachial artery (a. brachialis)
commences at the lower margin of the
tendon of the Teres major, and, passing
down the inner and anterior aspect of
the arm, terminates about half an inch
below the bend of the elbow, where it
divides into the radial and ulnar arteries.
At first the brachial artery lies internal
to the humerus ; but as it passes down
the arm it gradually gets in front of
the bone, and at the bend of the elbow
it lies midway between the two condyles.
Relations. — This artery is superficial
throughout its entire extent, being cov-
ered, in front, by the integument, the
superficial and deep fasciae; the bicipital
fascia separates it opposite the elbow
from the median basilic vein ; the median
nerve crosses it at its middle; behind, it
is separated from the long head of the
Triceps by the musculo-spiral nerve and
superior profunda artery. It then lies
upon the inner head of the Triceps, next
upon the insertion of the Coraco-bra-
chialis, and lastly on the Brachialis an-
ticus; by its outer side, it is in relation with the commencement of the median
nerve and the Coraco-brachialis and Biceps muscles, which overlap the artery
to a considerable extent; by its inner side, its upper half is in relation with the
internal cutaneous and ulnar nerves, its lower half with the median nerve. The
basilic vein lies on the inner side of the artery, but is separated from it in the
lower part of the arm by the deep fascia. The brachial artery is accompanied by
FIG. 415. — The brachial artery.
SURGICAL ANATOMY OF THE BEND OF THE ELBOW 655
two venae comites, which lie in close contact with the artery, being connected
together at intervals by short transverse communicating branches.
PLAN OF THE RELATIONS OF THE BRACHIAL ARTERY.
In front.
Integument and fasciae.
Bicipital fascia, median basilic vein.
Median nerve.
Overlapped by Coraco-brachialis and Biceps.
Outer side. / \ Inner side.
Median nerve (above). / Brachial j Internal cutaneous and Ulnar nerves.
Coraco-brachialis. I Artei7- I Median nerve (below).
Biceps. V J Basilic vein.
Behind.
Triceps (long and inner heads).
Musculo-spiral nerve.
Superior profunda artery.
Coraco-brachialis.
Brachialis anticus.
SURGICAL ANATOMY OF THE BEND OF THE ELBOW.
At the bend of the elbow the brachial artery sinks deeply into a triangular inter-
val, the antecubital space, the base of which is directed upward, and may be repre-
sented by a line connecting the two condyles of the humerus; the sides are bounded,
externally, by the inner edge of the Supinator longus ; internally, by the outer mar-
gin of the Pronator radii teres; its floor is formed by the Brachialis anticus and
Supinator brevis. This space contains the brachial artery with its accompanying
veins, the radial and ulnar arteries, the median and musculo-spiral nerves, and the
tendon of the Biceps. The brachial artery occupies the middle line of this space, and
divides opposite the neck of the radius into the radial and ulnar arteries; it is
covered, in front, by the integument, the superficial fascia, and the median basilic
vein, the vein being separated from direct contact with the artery by the bicipital
fascia. Behind, it lies on the Brachialis anticus, which separates it from the
elbow-joint. The median nerve lies on the inner side of the artery, close to it
above, but separated from it below by the coronoid origin of the Pronator radii
teres. The tendon of the Biceps lies to the outer side of the space, and the mus-
culo-spiral nerve still more externally, situated upon the Supinator brevis and
partly concealed by the Supinator longus.
Peculiarities of the Brachial Artery as Regards its Course.— The brachial artery, accom-
panied by the median nerve, may leave the inner border of the Biceps and descend toward the
inner condyle of the humerus, where it usually curves round a prominence of bone, the supra-
condylar process. From this process, in most subjects, a fibrous arch is thrown over the
artery. The vessel then inclines outward, beneath or through the substance of the Pronator
radii teres muscle, to the bend of the elbow. The variation bears considerable analogy to the
normal condition of the artery in some of the carnivora: it has been referred to in the descrip-
tion of the humerus (page 181).
As Regards its Division. — Occasionally, the artery is divided for a short distance at its upper
part into two trunks, which are united above and below. A similar peculiarity occurs in the main
vessel of the lower limb.
The point of bifurcation may be above or below the usual point, the former condition being
by far the more frequent. Out of 481 examinations recorded by Mr. Quain, some made on the
right and some on the left side of the body, in 386 the artery bifurcated in its normal position.
In one case only was the place of division lower than usual, being two or three inches below the
elbow-joint. "In 94 cases out of 481, or about 1 in 5^, there were two arteries instead of one
in some part or in the whole of the arm."
656 THE BLOOD -VASCULAR SYSTEM
There appears, however, to be no correspondence between the arteries of the two arms with
respect to their irregular division; for in 61 bodies it occurred on one side only in 43; on both
sides, in different positions, in 13; on both sides, in the same position, in 5.
The point of bifurcation takes place at different parts of the arm, being most frequent in
the upper part, less so in the lower part, and least so in the middle, the most usual point for
the application of a ligature ; under any of these circumstances two large arteries would be found
in the arm instead of one. The most frequent (in three out of four) of these peculiarities is
the high origin of the radial. That artery often arises from the inner side of the brachial,
and runs parallel with the main trunk to the elbow, where it crosses it, lying beneath the fascia;
or it may perforate the fascia and pass over the artery immediately beneath the integument.
The ulnar sometimes arises from the brachial high up, and accompanies that vessel to the
lower part of the arm, and descends toward the inner condyle. In the forearm it generally lies
beneath the deep fascia, superficial to the flexor muscles; occasionally between the integument
and deep fascia, and very rarely beneath the flexor muscles.
The interosseous artery sometimes arises from the upper part of the brachial or axillary; as
it passes down the arm it lies behind the main trunk, and at the bend of the elbow regains its
usual position.
In some cases of high origin of the radial the remaining trunk (ulnar interosseous) occa-
sionally passes, together with the median nerve, along the inner margin of the arm to the inner
condyle, and then passing from within outward, beneath or through the Pronator radii teres,
regains its usual position at the bend of the elbow.
Occasionally the two arteries representing the brachial are connected at the bend of the elbow
by a short transverse branch, and are even sometimes reunited.
Sometimes, long slender vessels, vasa aberrantia, connect the brachial or axillary arteries
with one of the arteries of the forearm or a branch from them. These vessels usually join the
radial.
Varieties in Muscular Relations.1 — The brachial artery is occasionally concealed in some
part of its course by muscular or tendinous slips derived from the Coraco-brachialis, Biceps,
Brachialis anticus, and Pronator radii teres muscles.
Surface Marking. — The direction of the brachial artery is marked by a line drawn along
the inner edge of the Biceps from the junction of the anterior and middle thirds of the axillary
outlet to the middle of the front of the elbow-joint.
Surgical Anatomy. — Compression of the brachial artery is required in cases of amputation
and some other operations in the arm and forearm; and it will be observed that it may be effected
in almost any part of the course of the artery. If pressure is made in the upper part of the
limb, it should be directed from within outward ; and if in the lower part, from before backward,
as the artery lies on the inner side of the humerus above and in front of the humerus below.
The most favorable situation is about the middle of the arm, where it lies on the tendon of the
Coraco-brachialis on the inner flat side of the humerus.
The application of a ligature to the brachial artery may be required in case of wound of
the vessel and in some cases of wound of the palmar arch. It is also sometimes necessary in
cases of aneurism of the brachial, the radial, ulnar, or interosseous arteries. The artery may
be secured in any part of its course. The chief guides in determining its position are the sur-
face markings produced by the inner margin of the Coraco-brachialis and Biceps, the known
course of the vessel, and its pulsation, which should be carefully felt for before any operation is
performed, as the vessel occasionally deviates from its usual position in the arm. In whatever
situation the operation is performed, great care is necessary, on account of the extreme thinness
of the parts covering the artery and the intimate connection which the vessel has throughout its
whole course with important nerves and veins. Sometimes a thin layer of muscular fibre is
met with concealing the artery; if such is the case, it must be cut across in order to expose the
vessel.
In the upper third of the arm the artery may be exposed in the following manner: The
patient being placed supine upon a table, the affected limb should be raised from the side and
the hand supinated. An incision about two inches in length should be made on the inner
side of the Coraco-brachialis muscle, and the subjacent fascia cautiously divided, so as to avoid
wounding the internal cutaneous nerve or basilic vein, which sometimes runs on the surface of
the artery as high as the axillary. The fascia having been divided, it should be remembered that
the ulnar and internal cutaneous nerves lie on the inner side of the artery, the median on the
outer side, the latter nerve being occasionally superficial to the artery in this situation, and that
the vense comites are also in relation with the vessel, one on either side. These being carefully
separated, the aneurism needle should be passed round the artery from the inner to the outer
side.
If two arteries are present in the arm in consequence of a high division, they are usually
placed side by side: and if they are exposed in an operation, the surgeon should endeavor to
1 See Struther's Anatomical and Physiological Observations.
BRANCHES OF THE BRACHIAL ARTERY 657
ascertain, by alternately pressing on each vessel, which of the two communicates with the wound
or aneurism, when a ligature may be applied accordingly; or if pulsation or hemorrhage ceases
only when both vessels are compressed, both vessels may be tied, as it may be concluded that
the two communicate above the seat of disease or are reunited.
It should also be remembered that two arteries may be present in the arm in a case of high
division, and that one of these may be found along the inner intermuscular septum, in a line
toward the inner condyle of the humerus, or in the usual position of the brachial, but deeply
placed beneath the common trunk: a knowledge of these facts will suggest the precautions
necessary in every case, and indicate the measures to be adopted when anomalies are met with.
In the middle of the arm the brachial artery may be exposed by making an incision along
the inner margin of the Biceps muscle. The forearm being bent so as to relax the muscle, it
should be drawn slightly aside, and, the fascia being carefully divided, the median nerve will be
exposed lying upon the artery (sometimes beneath); this being drawn inward and the muscle
outward, the artery should be separated from its accompanying veins and secured. In this
situation the inferior profunda may be mistaken for the main trunk, especially if enlarged, from
the collateral circulation having become established; this may be avoided by directing the
incision externally toward the Biceps, rather than inward or backward toward the Triceps.
The lower part of the brachial artery is of interest in a surgical point of view, on account
of the relation which it bears to the veins most commonly opened in venesection. Of these
vessels, the median basilic is the largest and most prominent, and, consequently, the one usually
selected for the operation. It should be remembered that this vein runs parallel with the
brachial artery, from which it is separated by the bicipital fascia, and that care should be taken
in opening the vein not to carry the incision too deeply, so as to endanger the artery.
Collateral Circulation. — After the application of a ligature to the brachial artery in the
upper third of the arm, the circulation is carried on by branches from the circumflex and sub-
scapular arteries, anastomosing with ascending branches from the superior profunda. If the
brachial is tied below the origin of the profunda arteries, the circulation is maintained by the
branches of the profundse, anastomosing with the recurrent radial, ulnar, and interosseous
arteries. In two cases described by Mr. South,1 in which the brachial artery had been tied some
time previously, in one "a long portion of the artery had been obliterated, and sets of vessels
are descending on either side from above the obliteration, to be received into others which ascend
in a similar manner from below it. In the other the obliteration is less extensive, and a single
curved artery about as big as a crow-quill passes from the upper to the lower open part of the
artery."
Branches. — The branches of the brachial artery are — the
Superior Profunda. Inferior Profunda.
Nutrient. Anastomotica Magna.
Muscular.
The Superior Profunda Artery (a. profunda brachii) arises from the inner and
back part of the brachial, just below the lower border of the Teres major, and
passes backward to the interval between the outer and inner heads of the Triceps
muscle; accompanied by the musculo-spiral nerve it winds around the back part of
the shaft of the humerus in the spiral groove, between the outer head of the Triceps
and the bone, to the outer side of the humerus, where it reaches the external inter-
muscular septum and divides into two terminal branches. One of these pierces
the external intermuscular septum, and descends, in company with the musculo-
spiral nerve, to the space between the Brachialis anticus and Supinator longus,
where it anastomoses with the recurrent branch of the radial artery; while the
other, much the larger of the two, descends along the back of the external inter-
muscular septum to the back of the elbow-joint, where it anastomoses with the
posterior interosseous recurrent, and across the back of the humerus with the pos-
terior ulnar recurrent, the anastomotica magna, and inferior profunda (Fig. 418).
The superior profunda supplies the Triceps muscle and gives off a nutrient artery
which enters the bone at the upper end of the musculo-spiral groove. Near its
commencement it sends off a branch which passes upward between the external
and long heads of the Triceps muscle to anastomose with the posterior circumflex
1 Chelius's Surgery, vol. ii. p. 254. See also White's engravings, referred to by Mr. South, of the anastomos-
ing branches after ligature of the brachial, in White's Cases in Surgery. Porta also gives a case (with drawings)
of the circulation after ligature of both brachial and radial (Alterazioni Patoligiche delle Arterie). — ED. of 15th
English edition.
42
658
THE BLOOD -VASCULAR SYSTEM
Sadial recurrent.
artery, and, while in the groove, a small branch which accompanies a branch of
the musculo-spiral nerve through the substance of the Triceps muscle and ends
in the Anconeus below the outer
condyle of the humerus.
The Nutrient Artery (a. nutricia
humeri) of the shaft of the hurnerus
arises from the brachial, about the
middle of the arm. Passing down-
ward it enters the nutrient canal of
that bone near the insertion of the
Coraco-brachialis muscle.
The Inferior Profunda (a. col-
lateralis ulnaris superior), of small
size, arises from the brachial, a little
below the middle of the arm ; pierc-
ing the internal intermuscular sep-
tum, it descends on the surface of
the inner head of the Triceps mus-
cle to the space between the inner
condyle and olecranon, accompanied
by the ulnar nerve, and terminates
by anastomosing with the posterior
ulnar recurrent and anastomotica
magna. It sometimes supplies a
branch to the front of the internal
condyle, which anastomoses with
the anterior ulnar recurrent.
The Anastomotica Magna (a.
collateralis ulnaris inferior) arises
from the brachial about two inches
above the elbow-joint. It passes
transversely inward upon the Bra-
chialis anticus, and, piercing the
internal intermuscular septum/winds
round the back of the humerus be-
tween the Triceps and the bone,
forming an arch above the olecranon
fossa by its junction with the poste-
rior articular branch of the superior
profunda. As this vessel lies on the
Brachialis anticus, branches ascend
to join the inferior profunda, and
others descend in front of the inner
condyle to anastomose with the an-
terior ulnar recurrent. Behind the
internal condyle an offset is given
off which anastomoses with the infe-
rior profunda and posterior ulnar
recurrent arteries and supplies the
Triceps.
The Muscular (rami musculares)
FIG. 416.— The radial and ulnar arteries. are ^hrCC or four large branches,
which are distributed to the muscles in the course of the artery. They supply
the Coraco-brachialis, Biceps, and Brachialis anticus muscles.
Deep branch
of ulnar.
Superficial™ volse.
THE RADIAL ARTERY 659
The Anastomosis around the Elbow- joint (Fig. 418). — The vessels engaged
in this anastomosis may be conveniently divided into those situated in front and
behind the internal and external condyles. The branches anastomosing in front
of the internal condyle are the anastomotica magna, the anterior ulnar recurrent,
and the anterior terminal branch of the inferior profunda. Those behind the in-
ternal condyle are the anastomotica magna, the posterior ulnar recurrent, and the
posterior terminal branch of the inferior profunda. The branches anastomosing
in front of the external condyle are the radial recurrent and the anterior terminal
branch of the superior profunda. Those behind the external condyle (perhaps
more properly described as being situated between the external condyle and the
olecranon)are the anastomotica magna, the interosseous recurrent, and the posterior
terminal branch of the superior profunda. There is also a large arch of anasto-
mosis above the olecranon, formed by the interosseous recurrent, joining with the
anastomotica magna and posterior ulnar recurrent.
From this description it will be observed that the anastomotica magna is the
vessel most engaged, the only part of the anastomosis in which it is not employed
being that in front of the external condyle.
The Radial Artery (A. Radialis) (Figs. 416, 417).
The radial artery appears, from its direction, to be the continuation of the
brachial, but in size it is smaller than the ulnar. It commences at the bifurcation of
the brachial, just below the bend of the elbow, and passes along the radial side of
the forearm to the wrist; it then winds backward, round the outer side of the carpus,
beneath the extensor tendons of the thumb, to the upper end of the space between
the metacarpal bones of the thumb and index ringer, and finally passes forward,
between the two heads of the First dorsal interosseous muscle, into the palm of the
hand, where it crosses the metacarpal bones to the ulnar border of the hand, to form
the deep palmar arch. At its termination it inosculates with the deep branch of the
ulnar artery. The relations of this vessel may thus be conveniently divided into
three parts — viz., in the forearm, at the back of the wrist, and in the hand.
Relations. — In the forearm this vessel extends from opposite the neck of the
radius to the forepart of the styloid process, being placed to the inner side of the
shaft of the bone above and in front of it below. It is overlapped in the upper
part of its course by the fleshy belly of the Supinator longus muscle; throughout
the rest of its course it is superficial, being covered by the integument, the super-
ficial and deep fasciae. In its course downward it lies upon the tendon of the
Biceps, the Supinator brevis, the Pronator radii teres, the radial origin of the
Flexor sublimis digitorum, the Flexor longus pollicis, the Pronator quadratus, and
the lower extremity of the radius. In the upper third of its course it lies between
the Supinator longus and the Pronator radii teres; in the lower two-thirds, between
the tendons of the Supinator longus and the Flexor carpi radialis. The radial
nerve lies close to the outer side of the artery in the middle third of its course,
and some filaments of the musculo-cutaneous nerve, after piercing the deep fascia,
run along the lower part of the artery as it winds round the wrist. The vessel is
accompanied by venre comites throughout its whole course.
PLAN OF THE RELATIONS OF THE RADIAL ARTERY IN THE FOREARM.
In front.
Skin, superficial and deep fasciae.
Supinator longus.
Inner side. f Radial \ Outer side.
Pronator radii teres. Forearm"1 / Supinator longus.
Flexor carpi radialis. V J Radial nerve (middle third).
660 THE BLOOD -VASCULAR SYSTEM
Behind.
Tendon of Biceps.
Supinator brevis.
Pronator radii teres.
Flexor sublimis digitorum.
Flexor longus pollicis.
Pronator quadratus.
Radius.
At the wrist, as it winds round the outer side of the carpus from the styloid
process to the first interosseous space, it lies upon the external lateral ligament,
and then upon the scaphoid bone and trapezium, being covered by the extensor
tendons of the thumb, subcutaneous veins, some filaments of the radial nerve, and
the integument. It is accompanied by two veins and a filament of the musculo-
cutaneous nerve.
In the hand it passes from the upper end of the first interosseous space,
between the heads of the Abductor indicis or First dorsal interosseous muscle,
transversely across the palm, to the base of the metacarpal bone of the little
finger, where it inosculates with the communicating branch from the ulnar artery,
forming the deep palmar arch.
The Deep Palmar Arch (arcus volaris profundus) (Fig. 417). — It lies upon the
carpal extremities of the metacarpal bones and the Interossei muscles, being
covered by the Adductor obliquus pollicis, the flexor tendons of the fingers, the
Lumbricales, the Opponens, and Flexor brevis minimi digiti. Alongside of it is
the deep branch of the ulnar nerve, but running in the opposite direction; that
is to say, from within outward. The branches of the deep palmar arch are the
palmar interosseous, perforating and palmar recurrent vessels (page 662).
Peculiarities. — The origin of the radial artery, according to Quain, is, in nearly one case
in eight, higher than usual; more frequently arising from the axillary or upper part of the brachial
than from the lower part of this vessel. The variations in the position of this vessel in the arm
and at the bend of the elbow have been already mentioned. In the forearm it deviates less fre-
quently from its position than the ulnar. It has been found lying over the fascia instead of
beneath it. It has also been observed on the surface of the Supinator longus, instead of under
its inner border; and in turning round the wrist it has been seen lying over, instead of beneath,
the extensor tendons of the thumb.
Surface Marking. — The position of the radial artery in the forearm is represented by a line
drawn from the outer border of the tendon of the Biceps in the centre of the hollow in front
of the elbow-joint with a straight course to the inner side of the forepart of the styloid process
of the radius.
Surgical Anatomy.— The radial artery is much exposed to injury in its lower third, and is
frequently wounded by the hand being driven through a pane of glass, by the slipping of a
knife or chisel held in the other hand, and similar accidents. The injury is often followed by
a traumatic aneurism, for which the operation of extirpating or laying open the sac after securing
the vessel above and below is required.
The operation of tying the radial artery is required in cases of wounds either of its trunk or
of some of its branches, or for aneurism; and it will be observed that the vessel may be exposed
in any part of its course through the forearm without the division of any muscular fibres. The
operation in the middle or inferior third of the forearm is easily performed, but in the upper
third, near the elbow, it is attended with some difficulty, from the greater depth of tlje vessel
and from its being overlapped by the Supinator longus muscle.
To tie the artery in the upper third an incision three inches in length should be made through
the integument, in a line drawn from the centre of the bend of the elbow to the front of the
styloid process of the radius, avoiding the branches of the median vein; the fascia of the arm
being divided and the Supinator longus drawn a little outward, the artery will be exposed. The
venae comites should be carefully separated from the vessel, and the ligature passed from the
radial to the ulnar side.
In the middle third of the forearm the artery may be exposed by making an incision of similar
length on the inner margin of the Supinator longus. In this situation the radial nerve lies in close
relation with the outer side of the artery, and should, as well as the veins, be carefully avoided.
In the lower third the artery is easily secured by dividing the integument and fascia in the
interval between the tendons of the Supinator longus and Flexor carpi radialis muscles.
THE RADIAL ARTERY
661
Branches (Figs. 416, 417, and 418).— The branches of the radial artery may
be divided into three groups, corresponding with the three regions in which the
vessel is situated.
In the
Forearm
Wrist
Radial Recurrent.
Muscular.
Anterior Radial Carpal.
Superficialis Volre.
Princeps Pollicis.
Radialis Indicis.
Posterior Radial Carpal.
Metacarpal.
1 )orsales Pollicis.
Dorsalis Indicis.
Hand
Perforating.
Palmar Interosseous.
Palmar Recurrent.
The Radial Recurrent (a. recurrens radialis) (Fig. 417) is given off imme-
diately below the elbow. It ascends between the branches of the musculo-spiral
nerve lying on the Supinator brevis, and then between the Supinator longus and
Brachialis anticus, supplying these muscles and the elbow-joint, and anastomosing
with the terminal branches of the superior profunda.
The Muscular Branches (rami musculares) are distributed to the muscles on
the radial side of the forearm.
The Anterior Radial Carpal (ramus carpeus volaris) (Fig. 417) is a small
vessel which arises from the radial artery near the lower border of the Pronator
quadratus, and, running inward in front of the radius, anastomoses with the ante-
rior carpal branch of the ulnar artery. In this way an arterial anastomosis, the
anterior carpal arch (rete carpi volare), is formed in front of the wrist; it is joined
by branches from the anterior interosseous above, and by recurrent branches from
the deep palmar arch below, and gives off branches which descend to supply the
articulations of the wrist and carpus.
The Superficialis Volse (ramus volaris superficialis) (Fig. 417) arises from the
radial artery, just where this vessel is about to wind round the wrist. Running
forward, it passes between, occasionally over, the muscles of the thumb, which it
supplies, and sometimes anastomoses with the palmar portion of the ulnar artery,
completing the superficial palmar arch. This vessel varies considerably in size:
usually it is very small, and terminates in the muscles of the thumb ; sometimes
it is as large as the continuation of the radial.
The Posterior Radial Carpal (ramus carpeus dorsalis) (Fig. 418) is a small
vessel which arises from the radial artery beneath the extensor tendons of the
thumb; crossing the carpus transversely to the inner border of the hand, it
anastomoses with the posterior carpal branch of the ulnar, forming the posterior
carpal arch (rete carpi dorsale) , which is joined by the termination of the anterior
interosseous artery. From this arch are given off descending branches, the
dorsal interosseous arteries (aa. metacarpeae dor sales) for the second, third, and
fourth interosseous spaces, which run forward on the Second, Third, and
Fourth dorsal interossei muscles, and divide into dorsal digital branches (aa.
digitales dorsales), which supply the adjacent sides of the index, middle, ring,
and little fingers respectively, communicating with the digital arteries of the
superficial palmar arch. The dorsal interosseous arteries anastomose with the
perforating branches from the deep palmar arch.
The Dorsales Pollicis (Fig. 418) are two vessels which run along the sides of
the dorsal aspect of the thumb. They arise separately, or occasionally by a
common trunk, near the base of the first metacarpal bone.
The Dorsalis Indicis (Fig. 418), also a small branch, runs along the radial side
of the back of the index finger, sending a few branches to the Abductor indicis.
662
THE BLOOD -VASCULAR SYSTEM
Anastomotica,
magna.
Radial
recurrent.
Posterior
•inter osseous.
Anterior ulnar
recurrent.
Posterior ulnar
recurrent.
The Princeps Pollicis (a. princeps pollicis) (Fig. 4l7)arises from the radial just as
it turns inward to the deep part of the hand ; it descends between the Abductor indicis
and Adductor obliquus pollicis, then
between the Adductor transversus
pollicis and Adductor obliquus
pollicis, along the ulnar side of the
metacarpal bone of the thumb, to
the base of the first phalanx, where
it divides into two branches, which
run along the sides of the palmar
aspect of the thumb, and form an
arch on the palmar surface of the
last phalanx, from which branches
are distributed to the integument
and pulp of the thumb.
The Radialis Indicis (a. volaris
indicis radialis) (Fig. 417) arises
close to the preceding, descends
between the Abductor indicis and
Adductor transversus pollicis, and
runs along the radial side of the
index finger to its extremity, where
it anastomoses with the collateral
digital artery from the superficial
palmar arch. At the lower border
of the Adductor transversus pollicis
this vessel anastomoses with the
princeps pollicis, and gives a com-
municating branch to the super-
ficial palmar arch.
The Perforating Arteries (rami
Muscular.
Anterior ca:
Superficial volse
in
perforantes) (Fig. 417), three
number, pass backward from the
deep palmar arch between the
heads of the last three Dorsal inter-
ossei muscles, to inosculate with
the dorsal interosseous arteries.
The Palmar Interosseous (aa.
metacarpeaevolares) (Fig. 417), three
or four in number, arise from the
convexity of the deep palmar arch ;
they run forward upon the Inter-
ossei muscles,and anastomose at the
clefts of the fingers with the digital
branches of the superficial arch.
The Palmar Recurrent Branches arise from the concavity of the deep palmar
arch. They pass upward in front of the wrist, supplying the carpal articulations
and anastomosing with the anterior carpal arch.
FIG. 417. — Ulnar and radial arteries. Deep view.
The Ulnar Artery (A. Ulnaris) (Figs. 416, 417).
The ulnar artery, the larger of the two terminal branches of the brachial,
commences a little below the bend of the elbow, and crosses obliquely the
THE ULNAR ARTERY 663
inner side of the forearm to the commencement of its lower half; it then
runs along its ulnar border to the wrist, crosses the annular ligament on the
radial side of the pisiform bone, and immediately beyond this bone divides into
two branches which enter into the formation of the superficial and deep palmar
arches.
Relations. In the Forearm. — In its upper half it is deeply seated, being cov-
ered by all the superficial Flexor muscles, excepting the Flexor carpi ulnaris; the
median nerve is in relation with the inner side of the artery for about an inch and
then crosses the vessel, being separated from it by the deep head of the Pronator
radii teres; it lies upon the Brachialis anticus and Flexor profundus digitorum
muscles. In the lower half of the forearm it lies upon the Flexor profundus, being
covered by the integument, the superficial and deep fasciae, and is placed between
the Flexor carpi ulnaris and Flexor sublimis digitorum muscles. It is accompanied
by two venae comites; the ulnar nerve lies on its inner side for the lower two-
thirds of its extent, and a small branch from the nerve descends on the lower part
of the vessel to the palm of the hand.
PLAN OF RELATIONS OF THE ULNAR ARTERY IN THE FOREARM.
In front.
Superficial layer of flexor muscles. ] TT
Median nerve. I UPPer half"
Superficial and deep fasciae. Lower half.
Inner side. ( Ulnar \ Outer side.
Artery in
Flexor carpi ulnaris. \ Forearm. ) Flexor sublimis digitorum.
Ulnar nerve (lower two-thirds). V^ /
Behind.
Brachialis anticus.
Flexor profundus digitorum.
At the wrist (Fig. 416) the ulnar artery is covered by the integument and fascia,
and lies upon the anterior annular ligament. On its inner side is the pisiform bone.
The ulnar nerve lies at the inner side, and somewhat behind the artery; here the
nerve and artery are crossed by a band of fibres, which extends from the pisiform
bone to the anterior annular ligament.
Peculiarities. — The ulnar artery has been found to vary in its origin nearly in the propor-
tion of one in thirteen cases, in one case arising lower than usual, about two or three inches
below the elbow, and in all other cases much higher, the brachial being a more frequent source
or origin than the axillary.
Variations in the position of this vessel are more frequent than in the radial. When its origin
is normal the course of the vessel is rarely changed. When it arises high up it is almost invaria-
bly superficial to the Flexor muscles in the forearm, lying commonly beneath the fascia, more
rarely between the fascia and integument. In a few cases its position was subcutaneous in the
upper part of the forearm, subaponeurotic in the lower part.
Surface Marking. — On account of the curved direction of the ulnar artery the line on the
surface of the body which indicates its course is somewhat complicated. First, draw a line from
the front of the internal condyle of the humerus to the radial side of the pisiform bone; the
lower two-thirds of this line represents the course of the middle and lower third of the ulnar
artery. Secondly, draw a line from the centre of the antecubital space to the junction of the
upper and middle third of the first line; this represents the course of the upper third of the
artery.
Surgical Anatomy. — The application of a ligature to this vessel is required in cases of wound
of the artery or of its branches, or in consequence of aneurism. In the upper half of the fore-
arm the artery is deeply seated beneath the superficial flexor muscles, and the application of a
ligature in this situation is attended with some difficulty. An incision is to be made in the
course of a line drawn from the front of the internal condyle of the humerus to the outer side
664 THE BLOOD VASCULAR SYSTEM
of the pisiform bone, so that the centre of the incision is three fingers' breadth below the internal
condyle. The skin and superficial fascia having been divided and the deep fascia exposed,
the white line which separates the Flexor carpi ulnaris from the other flexor muscles is to be
sought for, and the fascia incised in this line. The Flexor carpi ulnaris is now to be carefully
separated from the other muscles, when the ulnar nerve will be exposed, and must be drawn
aside. Some little distance below the nerve the artery will be found accompanied by its vense
comites, and it may be ligatured by passing the needle from within outward. In the middle and
lower third of the forearm this vessel may be easily secured by making an incision on the radial
side of the tendon of the Flexor carpi ulnaris: the deep fascia being divided, and the Flexor
carpi ulnaris and its companion muscle, the Flexor sublimis, being separated from each other,
the vessel will be exposed, accompanied by its vense comites, the ulnar nerve lying on its inner
side. The veins being separated from the artery, the ligature should be passed from the ulnar
to the radial side, taking care to avoid the ulnar nerve.
Branches (Figs. 416, 417, and 418). — The branches of the ulnar artery may
be arranged in the following groups:
Forearm
Wrist
Anterior Ulnar Recurrent.
Posterior Ulnar Recurrent.
, -Anterior Interosseous.
Interosseous •{ r> • T j
Posterior Interosseous.
Muscular.
Anterior Carpal.
Posterior Carpal.
, f Deep Palmar or Communicating.
Hand [Superficial Palmar Arch.
The Anterior Ulnar Recurrent (a. recurrences ulnaris anterior) (Fig. 417)
arises immediately below the elbow-joint, passes upward and inward between the
Brachialis anticus and Pronator radii teres, supplies twigs to those muscles, and,
in front, of the inner condyle anastomoses with the anastomotica magna and
inferior profunda.
The Posterior Ulnar Recurrent (a. recurrentes ulnaris posterior) (Figs. 417 and
418) is much larger, and arises somewhat lower than the preceding. It passes
backward and inward, beneath the Flexor sublimis, and ascends behind the inner
condyle of the humerus. In the interval between this process and the olecranon
it lies beneath the Flexor carpi ulnaris, and ascending between the heads of thai
muscle, in relation with the ulnar nerve ; it supplies the neighboring muscles and
joint, and anastomoses with the inferior profunda, anastomotica magna, and
interosseous recurrent arteries.
The Interosseous Artery (a. interossea communis) (Fig. 417) is a short trunk
about half an inch in length, and of considerable size, which arises immediately,
below the tuberosity of the radius, 'and, passing backward to the upper border oi
the interosseous membrane, divides into two branches, the anterior and posterior
interosseous.
The Anterior Interosseous (a. interossea volaris] (Fig. 417) passes down the fore-
arm on the anterior surface of the interosseous membrane, to which it is connected
by a thin aponeurotic arch. It is accompanied by the interosseous branch of the
median nerve, and overlapped by the contiguous margins of the Flexor profundus
digitorum and Flexor longus pollicis muscles, giving off in this situation muscular
branches and the nutrient arteries of the radius and ulna. At the upper border
of the Pronator quadratus a branch, anterior communicating artery, descends
beneath the muscle to anastomose in front of the carpus with the anterior carpal
arch. The continuation of the artery passes behind the Pronator quadratus, and,
piercing the interosseous membrane, reaches the back of the forearm, and anasto-
moses with the posterior interosseous artery (Fig. 418). It then descends to the
back of the wrist to join the posterior carpal arch. The anterior interosseous gives
THE ULNAR ARTERY
665
recurrent.
—Posterior interosseous.
off a long, slender branch, the median artery or artery comes nervi mediana
(a. mediana), which accompanies the median nerve and gives offsets to its sub-
stance. This artery is some-
iii / m .Descending branch from
times much enlarged, and ac- / ^fj superior profunda.
companies the nerve into the
palm of the hand.
The Posterior Interosseous
Artery (a. interossea dorsalis) Anastomotica
(Figs. 417 and 418) passes magna.
backward through the inter-
val between the oblique liga- Posterior uinar^
ment and the upper border of
the interosseous membrane.
It appears between the con-
tiguous borders of the Supina-
tor brevis and the Extensor
ossis metacarpi pollicis, and
runs down the back part of
the forearm, between the su-
perficial and deep layer of
muscles, to both of which it
distributes branches. At the
lower part of the forearm it
anastomoses with the termina-
tion of the anterior interosse-
ous artery. Then, continuing
its course over the head of
the ulna, it joins the posterior
carpal branch of the ulnar
artery. This artery gives off,
near its origin, the interosseous
recurrent branch.
The interosseous recurrent
artery (a. interossea recurrens)
(Fig.418) is a large vessel which
ascends to the interval between
the external condyle and olec-
ranon, on or through the fibres
of the Supinator brevis, but
beneath the Anconeus, anas-
tomosing with a branch from
the superior profunda, and
with the posterior ulnar recur-
rent and anastomotica magna.
The Muscular Branches
(rami muscidares) are distri-
buted to the muscles along
the ulnar side of the forearm.
The Anterior Carpal (ramus carpeus volaris) (Fig. 417) is a small vessel
which crosses the front of the carpus beneath the tendons of the Flexor pro-
fundus, and inosculates with a corresponding branch of the radial artery.
The Posterior Carpal (rarmis carpeus dorsalis) (Fig. 418) arises immediately
above the pisiform bone, and winds backward beneath the tendon of the Flexor
carpi ulnaris : it passes across the dorsal surface of the carpus beneath the extensor
Termination of an-
terior interosseous.
Posterior carpal
(ulnar).
Posterior carpal
(radial).
Radial.
vsalis pollicis.
Dorsalis indicia.
FIG. 418. — Arteries of the back of the forearm and.hand.
666 THE BLOOD -VASCULAR SYSTEM
tendons, anastomosing with a corresponding branch of the radial artery, and
forming the posterior carpal arch (rete carpi dorsale) (Fig. 418). Immediately after
its origin it gives off a small branch which runs along the ulnar side of the meta-
carpal bone of the little finger, forming one of the metacarpal arteries, and supplies
the ulnar side of the dorsal surface of the little finger.
The Deep or Communicating Branch to the Deep Palmar Arch (ramus
volaris profundus) (Fig. 417) passes deeply inward between the Abductor minimi
digiti and Flexor brevis minimi digiti, near their origins; it anastomoses with the
termination of the radial artery, completing the deep palmar arch.
The continuation of the trunk of the ulnar artery in the hand forms the greater
part of the superficial palmar arch.
The Superficial Palmar Arch (arcus volaris superficial™) (Fig. 416) is formed
by the ulnar artery in the hand, and is completed on the outer side by this vessel
anastomosing with a branch from the radialis indicis, though sometimes the arch
is completed by the ulnar anastomosing with the superficialis volse or the princeps
pollicis of the radial artery. The arch passes across the palm, describing a curve,
with its convexity forward, to the space between the ball of the thumb and the
index finger, where the above-mentioned anastomosis takes place.
Relations. — The superficial palmar arch is covered by the skin, the Palmaris
brevis, and the palmar fascia. It lies upon the annular ligament, the Flexor
brevis of the little finger, the tendons of the superficial flexor of the fingers, and
the divisions of the median and ulnar nerves.
PLAN OF THE RELATIONS OF THE SUPERFICIAL PALMAR ARCH.
In front.
Skin.
Palmaris brevis.
Palmar fascia.
Behind.
Annular ligament.
Flexor brevis of little finger.
Superficial flexor tendons.
Divisions of median and ulnar nerves.
Branches. — The branches of the Superficial Palmar Arch are the
Digital.
The Digital Branches (aa. digitales volares communes) (Fig. 416), four in number,
are given off from the convexity of the superficial palmar arch. They supply the
ulnar side of the little finger and the adjoining sides of the little, ring, middle, and
index fingers, the radial side of the index finger and thumb being supplied from
the radial artery. The digital arteries at first lie superficial to the flexor tendons,
but as they pass forward with the digital nerves to the clefts between the fingers
they lie between them, and are there joined by the interosseous branches from the
deep palmar arch. The digital arteries on the sides of the fingers lie beneath the
digital nerves; and about the middle of the last phalanx the two branches for each
finger form an arch, from the convexity of which branches pass to supply the
pulp of the finger.
THE THORACIC AORTA 667
Surface Marking. — The superficial palmar arch is represented by a curved line, starting
from the outer side of the pisiform bone and carried downward as far as the middle third of
the palm, and then curved outward on a level with the upper end of the cleft between the thumb
and index finger. The deep palmar arch is situated about half an inch nearer to the carpus.
Surgical Anatomy. — Wounds of the palmar arches are of special interest, and are always
difficult to deal with. When the superficial arch is wounded it is generally possible, by enlarging
the wound if necessary, to secure the vessel and tie it; or in cases where it is found impossible to
encircle the vessel with a ligature, a pair of haemostatic forceps may be applied and left on for
twenty-four or forty-eight hours. Wounds of the deep arch are not so easily dealt with. It may
be possible to secure the vessel by ligature or by forcipressure forceps, which may be left on;
or, failing in this, the wound may be carefully plugged with gauze and an outside dressing care-
fully bandaged on. The plug should be allowed to remain untouched for three or four days.
In wounds of the deep palmar arch a ligature may be applied to the bleeding points from the
dorsum of the hand by resection of the upper part of the third metacarpal bone. It is -useless
in these cases to ligate one of the arteries of the forearm alone, and indeed simultaneous Hga-
tion of both radial and ulnar arteries above the wrist is often unsuccessful, on account of the
anastomosis carried on by the carpal arches. Therefore, if unable to ligate the divided ends
of the arch, upon the failure of pressure to arrest hemorrhage, it is expedient to apply a ligature
to the brachial artery.
ARTERIES OF THE TRUNK.
THE DESCENDING AORTA (Figs. 419, 420).
The descending aorta is divided into two portions, the thoracic and abdominal,
in correspondence with the two great cavities of the trunk in which it is situated.
The Thoracic Aorta (Aorta Thoracalis) (Fig. 419).
The thoracic aorta commences at the lower border of the fourth thoracic
vertebra, on the left side, and terminates at the aortic opening in the Diaphragm,
in front of the lower border of the last thoracic vertebra. At its commencement
it is situated on the left side of the spine; it approaches the median line as it
descends, and at its termination lies directly in front of the spinal column. The
direction of this vessel being influenced by the spine, upon which it rests, it
describes a curve which is concave forward in the thoracic region. As the branches
given off from it are small, the diminution in the size of the vessel is inconsider-
able. It is contained in the back part of the posterior mediastinum.
Relations. — It is in relation, in front, from above downward, with the root of
the left lung, the pericardium, the oesophagus, and the Diaphragm: behind, with
the vertebral column and the vena? azygos minor; on the right side, with the vena
azygos major and thoracic duct; on the left side, with the left pleura and lung.
The oesophagus, with its accompanying nerves, lies on the right side of the aorta
above; but at the lower part of the thorax it gets in front of the aorta, and close
to the Diaphragm is situated to its left side.
PLAN OF THE RELATIONS OF THE THORACIC AORTA.
In front.
Root of left lung.
Pericardium.
(Esophagus.
Diaphragm.
Right side. y >> Left side.
(Esophagus (above). [ Thoracic \ Pleura.
Vena azygos major. l Aorta. I Left lung.
Thoracic duct. J (Esophagus (below).
Behind.
Vertebral column.
Superior and inferior azygos minor veins.
THE BLOOD -VASCULAR SYSTEM
The aorta is occasionally found to be obliterated at a particular spot— viz., at the junction of
the arch with the thoracic aorta just below the ductus arteriosus. Whether this is the result of
disease or of congenital malformation is immaterial to our present purpose; it affords an interest-
ing opportunity of observing the resources of the collateral circulation. The course of the anas-
tomosing vessels, by which the blood is brought from the upper to the lower part of the artery,
will be found well described in an account of two cases in the Pathological Transactions, vols. viii.
and x. In the former (p. 162) Mr. Sydney Jones thus sums up the detailed description of the
anastomosing vessels: "The principal communications by which the circulation was carried on,
were— Firstly, the internal mammary, anastomosing with the intercostal arteries, with the phrenic
of the abdominal aorta by means of the musculo-phrenic and comes nervi phrenici, and largely
with the deep epigastric. Secondly, the superior intercostal, anastomosing anteriorly by means
of a large branch with the first aortic intercostal, and posteriorly with the posterior branch of the
same artery. Thirdly, the inferior thyroid, by means of a branch about the size of an ordinary
radial, formed a communication with the first aortic intercostal. Fourthly, the transversalis colli,
by means of very large communications with the posterior branches of the intercostals. Fifthly,
the branches (of the subclavian and axillary) going to the side of the chest were large, and anas-
tomosed freely with the lateral branches of the intercostals." In the second case also (vol. x.
p. 97) Mr. Wood describes the anastomoses in a somewhat similar manner, adding the remark
that "the blood which was brought into the aorta through the anastomoses of the intercostal
arteries appeared to be expended principally in supplying the abdomen and pelvis, while the
supply to the lower extremities had passed through the internal mammary and epigastrics."
Surgical Anatomy. — The student should now consider the effects likely to be produced by
aneurism of the thoracic aorta, a disease of common occurrence. When we consider the great
depth of the vessel from the surface and the number of important structures which surround it
on every side, it may easily be conceived what a variety of obscure symptoms may arise from dis-
ease of this part of the arterial system, and how they may be liable to be mistaken for those of
other affections. Aneurism of the thoracic aorta most usually extends backward along the left
side of the spine, producing absorption of the bodies of the vertebrae, with curvature of the spine;
whilst the irritation or pressure on the cord will give rise to pain, either in the chest, back, or
loins, with radiating pain in the left upper intercostal spaces, from pressure on the intercostal
nerves ; at the same time the tumor may project backward on each side of the spine, beneath the
integument, as a pulsating swelling, simulating abscess connected with diseased bone, or it may
displace the oesophagus and compress the lung on one or the other side. If the tumor extend
forward, it may press upon and displace the heart, giving rise to palpitation and other symptoms
of disease of that organ; or it may displace, or even compress, the resophagus, causing pain and
difficulty of swallowing, as in stricture of that tube; and ultimately even open into it by ulcera-
tion, producing fatal hemorrhage. If the disease extends to the right side, it may press upon
the thoracic duct; or it may burst into the pleural cavity or into the trachea or lung; and, lastly,
it may open into the posterior mediastinum.
Branches. — Branches of the thoracic aorta supply the thoracic viscera.
They are known as rami viscerales. The rarai viscerales are the bronchial, cesoph-
ageal, pericardial, and mediastinal arteries. Other branches of the thoracic aorta
supply the walls of the chest* They are known as rami parietales or intercostal arteries.
The Bronchial Arteries (aa. bronchiales) are the nutrient vessels of the lungs,
and vary in number, size, and origin. That of the right side arises from the first
aortic intercostal, or by a common trunk with the left bronchial from the front of
the thoracic aorta. Those of the left side, usually two in number, arise from the
thoracic aorta, one a little lower than the other. Each vessel is directed to the
back part of the corresponding bronchus along which it runs, dividing and sub-
dividing along the bronchial tube, supplying them, the cellular tissue of the lungs,
the bronchial glands, and the oesophagus.
The (Esophageal Arteries (aa. oesophageae), usually four or five in number,
arise from the front of the aorta, and pass obliquely downward to the oesophagus,
forming a chain of anastomoses along that tube, anastomosing with the oesoph-
ageal branches of the inferior thyroid arteries above, and with ascending branches
from the phrenic and gastric arteries below.
The Pericardiac (rami pericardiaci) are a few small vessels, irregular in their
origin, distributed to the pericardium.
The Posterior Mediastinal Arteries (rami mediastinales] are numerous
small vessels which supply the glands and loose areolar tissue in the mediastinum.
THE THORACIC AORTA
669
The lower mediastinal branches are known as the superior phrenic arteries (aa.
phren leaf super lores), and are distributed to the posterior portion of the Diaphragm.
The Intercostal Arteries (aa. intercostales] (Fig. 419) arise from the back of the
aorta. The aortic intercostals are usually nine in number on each side, the two
superior intercostal spaces being supplied
by the superior intercostal, a branch of the
subclavian. The second space usually
receives a considerable branch from the
first aortic intercostal, which joins with
the branch from the superior intercostal
of the subclavian. The branch which runs
along the lower border of the last rib is
named the subcostal artery. The right
intercostals are longer than the left, on
account of the position of the aorta on the
left side of the spine: they pass outward,
across the bodies of the vertebra, to the
intercostal spaces, being covered by the
pleura, the oesophagus, thoracic duct,
sympathetic nerve, and the vena azygos
major; the left, passing outward, are
crossed by the sympathetic ; the upper two
are also crossed by the superior inter-
costal vein, the lower by the azygos minor
veins. In each intercostal space the artery
passes outward, the External intercostal
muscle being behind, the pleura and a thin
fascia being in front. It then passes be-
tween the two layers of Intercostal mus-
cles, and, having ascended obliquely to
the lower border of the rib above it, is
continued forward in the groove on its
lower border and anastomoses with the
anterior intercostal branches of the in-
ternal mammary. The first aortic inter-
costal anastomoses with the superior in-
tercostal branch of the subclavian, and
the last three intercostals pass between
the abdominal muscles, inosculating with the epigastric in front and with the
phrenic and lumbar arteries. Each intercostal artery is accompanied by a vein and
nerve, the former being above, and the latter below, except in the upper inter-
costal spaces, where the nerve is at first above the artery. The arteries are pro-
tected from pressure during the action of the Intercostal muscles by fibrous arches
thrown across, and attached by each extremity to the bone. The lower intercostal
arteries are continued anteriorly from the intercostal spaces into the abdominal
wall, except the subcostal, which lies throughout its whole course in the abdominal
wall, since it is placed below the last rib. They pass behind the costal cartilages
between the Internal oblique and Transversalis muscle to the sheath of the Rectus,
where they anastomose with the internal mammary and the deep epigastric
arteries. Behind, the subcostal artery anastomoses with the first lumbar artery.
Branches. — Each intercostal artery gives off numerous muscular branches (rami
musculares).
Lateral cutaneous. Muscular.
Posterior or dorsal branch. Collateral intercostal.
FIG. 419. — Thoracic aorta. (Testut.)
670 THE BLOOD -VASCULAR SYSTEM
Lateral Cutaneous Branches (rami cutanei laterales) come off from each intercostal
and take a similar course to that of the lateral cutaneous branch of the intercostal
nerve. These arteries are distributed to the walls of the chest and to the mammary
gland (rami mammarii laterales).
Small branches pass to the mammary gland through the fourth, fifth, and sixth
interspaces (rami mammarii medialis), and to the skin to the inner side of the
nipple (rami cutanei anteriores).
The portion of the artery considered here as the prolongation of the main trunk
is called by Spalteholz and others the anterior branch (ramus anterior).
The Posterior or Dorsal Branch (ramus posterior) of each intercostal artery passes
backward to the inner side of the anterior costo-transverse ligament, and divides
into an external branch (ramus cutaneus lateralis), and an internal branch (ramus
cutaneus medialis), which are distributed to the muscles and integument of the
back. Muscular branches (rami musculares) are given off by the dorsal branch soon
after its origin. A spinal branch (ramus spinalis) comes off from the dorsal
branch of the intercostal. It traverses the vertebral arches and enters the spinal
canal through the intervertebral foramen, is distributed to the spinal cord and
its membranes, and td the bodies of the vertebrae in the same manner as the
lateral spinal branches from the vertebral. It gives off three branches, the
neural, which accompanies the spinal nerve-roots, and is distributed to the mem-
branes of the spinal cord. The post-central branch divides into ascending and
descending branches, which, anastomosing with similar branches above and
below, form a series of vertical arches in the back of the bodies of the verte-
brae.1 The prelaminar branch is distributed to "the posterior wall of the spinal
canal."2
The Collateral Intercostal Branch comes off from the intercostal artery near the
angle of the rib, and descends to the upper border of the rib below, along which
it courses to anastomose with the anterior intercostal branch of the internal
mammary or its branch, the musculo-phrenic.
The two lower intercostals on each side have not constant collateral branches.
Even when present they are of small size and end in the wall of the abdomen.
Each collateral intercostal branch gives off muscular branches.
Surgical Anatomy. — The position of the intercostal vessels should be borne in mind in
performing the operation of paracentesis thoracis. The puncture should never be made nearer
the middle line posteriorly than the angle of the rib, as the artery crosses the space internal to
this .point. In the lateral portion of the chest, where the puncture is usually made, the artery
lies at the upper part of the intercostal space, and therefore the puncture should be made just
above the upper border of the rib forming the lower boundary of the space.
The Abdominal Aorta (Aorta Abdominalis) (Fig. 420).
The abdominal aorta commences at the aortic opening of the Diaphragm, in
front of the lower border of the body of the last thoracic vertebra, and, descending
a little to the left side of the vertebral column, terminates on the body of the fourth
lumbar vertebra, commonly a little to the left of the middle line,3 where it
divides into the two common iliac arteries. It diminishes rapidly in size, in
consequence of the many large branches which it gives off. As it lies upon the
bodies of the vertebrae, the curve which it describes is convex forward, the
greatest convexity corresponding to the third lumbar vertebra, which is a little
above and to the left side of the umbilicus.
1 Cunningham's Text-book of Anatomy. 2 Ibid.
8 Lord Lister, having accurately examined 30 bodies in order to ascertain the exact point of termination of
this vessel, found it " either absolutely, or almost absolutely, mesial in 15, while in 13 it deviated more or less
to the left, and in 2 was slightly to the right" (System of Surgery, edited by T. Holmes, 2d ed., vol. v. p. 652).
— ED. of 15th English edition.
THE ABDOMINAL AORTA
671
Relations. — It is covered, in front, by the lesser omentum and stomach, behind
which are the branches of the cocliac axis and the solar plexus; below these, by
the splenic vein, the pancreas, the left renal vein, the transverse portion of the
duodenum, the mesentery, and aortic plexus. Behind, it is separated from the
lumbar vertebrae and intervening disks by the anterior common ligament and left
\
FIG. 420. — The abdominal aorta and its branches.
lumbar veins. On the right side it is in relation with the postcava (the right crus
of he Diaphragm being interposed above), the vena azygos major, thoracic duct
and right sermlunar ganglion; on the left side, with the sympathetic nerve and
lett semilunar ganglion.
672 THE BLOOD -VASCULAR SYSTEM
PLAN OF THE RELATIONS OF THE ABDOMINAL AORTA,,
In front.
Lesser omentum and stomach.
Branches of the coeliac axis and solar plexus.
Splenic vein.
Pancreas.
Left renal vein.
Transverse duodenum.
Mesentery.
Aortic plexus.
Right side. ^ ^^
Right crus of Diaphragm. / \ Left side.
Postcava. ^rt^*1 Sympathetic nerve.
Vena azygos major. \ I Left sernilunar ganglion.
Thoracic duct. \. ./
Right semilunar ganglion.
Behind.
Left lumbar .veins.
Vertebral column.
Surface Marking. — In order to map out the abdominal aorta on the surface of the abdomen,
a line must be drawn from the middle line of the body, on a level with the distal extremity of
the seventh costal cartilage, downward and slightly to the left, so that it just skirts the umbilicus,
to a zone drawn round the body opposite the highest point of the crest of the ilium. This
point is generally half an inch below and to the left of the umbilicus, but as the position of this
structure varies with the obesity of the individual, it is not a reliable landmark as to the situation
of the bifurcation of the aorta.
Surgical Anatomy. — Aneurisms of the abdominal aorta near the cceliac axis communicate
in nearly equal proportion with the anterior and posterior parts of the artery.
When an aneurismal sac is connected with the back part of the abdominal aorta, it usually
produces absorption of the bodies of the vertebrae, and forms a pulsating tumor that presents
itself in the left hypochondriac or epigastric regions, and is accompanied by symptoms of dis-
turbance in the alimentary canal. Pain is invariably present, and is usually of two kinds — a
fixed and constant pain in the back, caused by the tumor pressing on or displacing the branches
of the solar plexus and splanchnic nerves; and a sharp lancinating pain, radiating along those
branches of the lumbar nerves which are pressed on by the tumor; hence the pain in the loins,
the testes, the hypogastrium, and in the lower limb (usually of the left side). This form of
aneurism usually bursts into the peritoneal cavity or behind the peritoneum in the left hypo-
chondriac region; or it may form a large aneurismal sac, extending down as low as Poupart's
ligament; hemorrhage in these cases being generally very extensive, but slowly produced, and
not rapidly fatal.
When an aneurismal sac is connected with the front of the aorta near the coeliac axis it
forms a pulsating tumor in the left hypochondriac or epigastric regions, usually attended with
symptoms of disturbance of the alimentary canal, as sickness, dyspepsia, or constipation, and
is accompanied by pain, which is constant, but nearly always fixed in the loins, epigastrium, or
some part of the abdomen; the radiating pain being rare, as the lumbar nerves are seldom
implicated. This form of aneurism may burst into the peritoneal cavity or behind the peri-
toneum, between the layers of the mesentery, or, more rarely, into the duodenum; it seldom
extends backward so as to affect the spine.
The abdominal aorta has been tied 1 5 times, and although none of the patients permanently
recovered, still, as Prof. Keen's lived 48 days, the possibility of the re-establishment of the
circulation is proved. In the lower animals this artery has been often successfully tied. The
vessel may be reached in several ways. In the original operation, performed by Sir A. Cooper,
in 1817, an incision was made in the linea alba, the peritoneum opened in front, the finger
carried down amongst the intestines toward the spine, the peritoneum again opened behind by
scratching through the mesentery, and the vessel thus readied. Or either of the operations
described below for securing the common iliac artery may, by extending the dissection a suf-
ficient distance upward, be made use of to expose the aorta. The chief difficulty in the
dead subject consists in isolating the artery in consequence of its great depth; but in the
living subject the embarrassment resulting from the proximity of the aneurismal tumor, and
the great probability of disease in the vessel itself, add to the dangers and difficulties of this
formidable operation so greatly that it is very doubtful whether it ought ever to be performed.
The collateral circulation would be carried on by the anastomosis between the internal mam-
THE ABDOMINAL AORTA 673
mary and the deep epigastric; by the free communication between the superior and inferior
mesenteries if the ligature were placed above the latter vessel; or by the anastomosis between
the inferior mesenteric and the internal pudic when (as is more common) the point of ligature is
below the origin of the inferior mesenteric; and possibly by the anastomoses of the lumbar
arteries with the branches of the internal iliac.
During an amputation at the hip the circulation through the abdominal aorta may be com-
manded by an assistant, who throws the entire weight of his body upon his rigidly extended
forearm, the fist of which lies directly upon the patient's aorta (Macewen's method). The
abdominal tourniquet is no longer used, as modern methods enable the surgeon to do a prac-
tically bloodless hip-joint amputation (Wyeth's method, Senn's method, McBurney's method).
Branches (Fig. 420). — The branches of the abdominal aorta are — the
pi • C Gastric. Superior Mesenteric. Ovarian in female.
r™ . \v'^\ Hepatic. Suprarenal. Inferior Mesenteric.
V>Oclld,C .rLXlb I c< 1 • -r> i T i
(^ Splenic. Renal. Lumbar.
Spermatic in male. Sacra Media.
Branches. — The branches of the abdominal aorta may be divided into two
sets: 1. Those supplying the viscera (rami vicerales). 2. Those distributed to
the walls of the abdomen (rami parietales).
Visceral Branches. Parietal Branches.
( Gastric.
Coeliac Axis< Hepatic. Inferior Phrenic.
I Splenic. Lumbar.
Superior Mesenteric. Sacra Media.
Inferior Mesenteric.
Suprarenal.
Renal.
Spermatic or Ovarian.
To expose the cceliac axis raise the liver, draw down the stomach, and then tear through the
layers of the lesser omen turn.
The Cceliac Axis or Artery (a. coeliaca) (Figs. 420, 421, and 422). — The coeliac
axis is a short thick trunk, about half an inch in length, which arises from the
aorta, close to the margin of the opening in the Diaphragm, behind the posterior
parietal peritoneum, above the pancreas, and below the twelfth thoracic vertebra,
and, passing nearly horizontally forward (in the erect posture), divides into three
large branches, the gastric, hepatic, and splenic, occasionally giving off one of the
phrenic arteries.
Relations. — It is covered by the lesser omentum. On the right side it is in
relation with the right semilunar ganglion and the lobus Spigelii; on the left side,
with the left semilunar ganglion and cardiac end of the stomach. Below, it rests
upon the upper border of the pancreas.
The Gastric or Coronary Artery (a. gastrica sinistra) (Figs. 421 and 422), the small-
est of the three branches of the coeliac axis, passes upward and to the left side,
behind the peritoneum of the lesser peritoneal cavity, raising this portion of the
peritoneum into a fold, known as the left or secondary pancreatico -gastric fold. It
continues this course until it nearly reaches the lesser curvature of the stomach just
below the cardia. It then turns to the front and curves forward to the cardiac
orifice of the stomach, distributing branches to the oesophagus which anastomose
with the aortic oesophageal arteries; others supply the cardiac end of the stomach,
inosculating with branches of the splenic artery; it then passes from left to
right, along and upon the lesser curvature of the stomach and beneath the
peritoneum to the pylorus, lying in its course between the layers of the lesser
omentum, and sometimes dividing into two vessels, which run along each side
43
674
THE BLOOD-VASCULAR SYSTEM
of the lesser curvature. One vascular arch gives branches to the anterior
wall of the stomach and the other to the posterior wall, and both give them
to the lesser omentum or the single artery gives branches to both surfaces
of the organ and to the lesser omentum : at its termination it anastomoses with
the pyloric branch or the two pyloric branches of the hepatic. It gives off
gastric branches to both the anterior and posterior surfaces of the stomach,
branches to the lesser omentum, a small hepatic branch, to the left lobe of the liver
and oesophageal branches (rami oesophagei) which anastomose with cesophageal
branches from the thoracic aorta and the inferior phrenic.
Oystic artery.
e af
FIG. 421. — The cceliac axis and its branches, the liver having been raised and the lesser omentum removed.
The Hepatic Artery (a. hepatica) (Figs. 421 and 422) in the adult is intermediate
in size between the gastric and splenic; in the foetus it is the largest of the three
branches of the cceliac axis. It is first directed forward and to the right, in the
right pancreatico-gastric fold, to the upper margin of the pyloric end of the
stomach, forming the lower boundary of the foramen of Winslow. It then passes
upward between the layers of the lesser omentum, and in front of the foramen of
Winslow, to the transverse fissure of the liver, where it divides into two branches,
right and left, which supply the corresponding lobes of that organ, accompanying
the ramifications of the vena portae and hepatic duct. The hepatic artery, in
its course along the right border of the lesser omentum, is in relation with the
ductus communis choledochus and portal veins, the duct lying to the right of
the artery and the vena portse behind.
THE ABDOMINAL AORTA
675
Its branches (Figs. 421 and 422) are — the
Pyloric.
Gastro-duodenalis
Cystic.
j Gastro-epiploica Dextra.
| Pancreatico-duodenalis Superior
The pyloric or superior pyloric branch (a. gastrica dextra) arises from the
hepatic, above the pylorus, descends between the layers of the lesser omentum
to the pyloric end of the stomach, and passes from right to left along its lesser cur-
vature, supplying it with branches and inosculating with the gastric branches of
the coronary artery. The vessel often divides into two vascular arches to anas-
tomose with two vascular arches from the gastric.
FIG. 422. — The coeliac axis and its branches, the stomach having been raised and the transverse mesocolon
removed (semi-diagrammatic).
The gastro-duodenalis (Fig. 422) is a short but large branch, which descends
near the pylorus, behind the first portion of the duodenum, and divides at the
lower border of this viscus into two branches, the gastro-epiploica dextra and the
pancreatico-duodenalis superior. Previous to its division, it gives off two or three
small inferior pyloric branches, to the pyloric end of the stomach and pancreas.
The gastro-epiploica dextra runs from right to left along but distinctly below
the greater curvature of the stomach, between the layers of the great omentum,
anastomosing about the middle of the lower border of the stomach with the gastro-
epiploica sinfstra from the splenic artery. This vessel gives off numerous branches,
676 THE BLOOD -VASCULAR SYSTEM
some of which ascend to supply both surfaces of the stomach, whilst others
descend to supply the great omentum (rami epiploici).
The pancreatico-duodenalis superior descends between the contiguous margins
of the duodenum and pancreas. It supplies the head of the pancreas by means
of the rami pancreatica, and the duodenuni by means of the rami duodenalis,
and anastomoses with the inferior pancreatico-duodenal branch of the superior
mesenteric artery and with the pancreatic branches of the splenic.
The cystic artery (a. cystica) (Fig. 421), usually a branch of the right hepatic,
passes downward and forward along the cystic duct to the gall-bladder, and
divides into two branches, one of which ramifies on its free surface beneath
the peritoneum, the other between the gall-bladder and the substance of the
liver.
The Splenic Artery (a. lienalis} (Figs. 421 and 422), in the adult, is the largest of
the three branches of the creliac axis, and is remarkable for the extreme tortuosity
of its course. It passes horizontally to the left side, behind the peritoneum and
along the upper border of the pancreas, accompanied by the splenic vein, which lies
below it, and on arriving near the spleen divides into branches, some of which
enter the hilum of that organ to be distributed to its structure, whilst others are
distributed to the pancreas and great end of the stomach. Its branches are — the
Pancreaticae Parvce. Gastric (Vasa Brevia).
Pancreatica Magna. Gastro-epiploica Sinistra.
Rami Lienalis.
The pancreatic branches (rami pancreatici) are numerous small branches
derived from the splenic as it runs behind the upper border of the pancreas,
supplying its middle and left parts. One of these, larger than the rest, is given
off from the splenic near the left extremity of the pancreas; it runs from left
to right near the posterior surface of the gland, following the course of the pan-
creatic duct, and is called the pancreatica magna. The others are called the
pancreaticae parvae. These vessels anastomose with the pancreatic branches of
the pancreatico-duodenal arteries, derived from the hepatic on the one hand and
superior mesenteric on the other.
The gastric branches or vasa brevia (aa. gastricae breves) consists of from five to
seven small branches, which arise either from the termination of the splenic
artery or from its terminal branches, and, passing from left to right, between
the layers of the gastro-splenic omentum, are distributed to the great curvature
of the stomach, anastomosing with branches of the gastric and gastro-epiploica
sinistra arteries.
The gastro-epiploica sinistra, the largest branch of the splenic, runs from left
to right along but distinctly below the great curvature of the stomach, between
the layers of the great omentum, and anastomoses with the gastro-epiploica
dextra. In its course it distributes several branches to the stomach, which
ascend upon both surfaces; others descend to supply the omentum.
The rami lienales leave the splenic artery in the hilum and pass into the spleen.
Surgical Anatomy. — The operation of pylorectomy can be made an almost bloodless pro-
cedure by tying the gastric, the pyloric, and the right and left gastro-epiploic arteries. "The
gastric is doubly tied about one inch below the cardiac orifice at a point where it joins the lesser
curvature and is divided between the ligatures. The superior pyloric is doubly tied and divided.
The fingers are passed beneath the pylorus, raising the gastro-colic omentum from the trans-
verse mesocolon, and in this way safe ligation behind the pylorus of the right gastro-epiploic
artery, or in most cases its parent vessel, the gastro-duodenal, is secured. The left gastro-
epiploic is now tied at an appropriate point, and the necessary amount of gastro-colic omentum
doubly tied and cut."1
1 William J. Mayo. Annals of Surgery, March, 1904.
THE ABDOMINAL AORTA 677
The Superior Mesenteric Artery (a. mesenterica superior] (Figs. 420 and 423).
— The superior mesenteric artery supplies the whole length of the small intestine,
except the first part of the duodenum ; it also supplies the cuecum and the ascending
and transverse colon ; it is a vessel of large size, arising from the forepart of the
aorta about a quarter of an inch below the cosliac axis; being covered at its origin
by the splenic vein and pancreas. It passes forward, between the pancreas and the
transverse portion of the duodenum, crosses in front of this portion of the intes-
tine, and descends between the layers of the mesentery to the right iliac fossa,
where, considerably diminished in size, it anastomoses with one of its own branches
— viz., the ileo-colic. In its course it forms an arch, the convexity of which is
directed forward and downward to the left side, the concavity backward and
upward to the right. It is accompanied by the superior mesenteric vein, and is
surrounded by the superior mesenteric plexus of nerves.
In order to expose the superior mesenteric artery raise the great omentum and transverse
colon, draw down the small intestines, and cut through the peritoneum where the transverse
mesocolon and mesentery join; the artery will then be exposed just as it issues from beneath
the lower border of the pancreas
Branches. — Its branches are — the
Inferior Pancreatico-duodenal. Ileo-colic.
Vasa Intestini Tenuis. Right Colic.
Middle Colic.
The Inferior Pancreatico-duodenal (a. pancreaticoduodenalis inferior] is given
off from the superior mesenteric, or from its first intestinal branch behind the
pancreas. It courses to the right between the head of the pancreas and duodenum,
and then ascends to anastomose with the superior pancreatico-duodenal artery.
It distributes branches to the head of the pancreas and to the transverse and
descending portions of the duodenum.
The Vasa Intestini Tenuis (aa. intestinales] arise from the convex side of the
superior mesenteric artery. They are usually from twelve to fifteen in number,
and are distributed to the jejunum (aa. jcjunales] and ileum (aa.ileae]. They
run parallel with one another between the layers of the mesentery, each vessel
dividing into two branches, which unite with similar branches on each side,
forming a series of arches the convexities of which are directed toward the
intestine. From this first set of arches branches arise, which again unite with
similar branches from either side, and thus a second series of arches is formed;
and from these latter, a third and a fourth, or even a fifth, series of arches is
constituted, diminishing in size the nearer they approach the intestine. From
the terminal arches numerous small straight vessels arise which encircle the
intestine, upon which they are distributed, ramifying between its coats. Through-
out their course small branches are given off to the glands and other structures
between the layers of the mesentery. (See the description of the vascular loops
in the section upon the Intestines. The form and arrangement of the loops
have been studied by Monks, of Boston.)
The Ileo-colic Artery (a. ileocolica] is the lowest branch given off from the
concavity of the superior mesenteric artery. It descends between the layers of
the mesentery to the right iliac fossa, where it divides into two branches. Of
these, the inferior division inosculates with the termination of the superior mesen-
teric artery, forming with it an arch, from the convexity of which branches
proceed to supply* the termination of the ileum, the caecum, the vermiform
appendix, and the ileo-csecal valve. The superior division inosculates with
the colica dextra and supplies the commencement of the colon.
The Right Colic Artery (a. colica dextra] arises from about the middle of the
concavity of the superior mesenteric artery, and, passing behind the peritoneum
678
THE BLOOD -VASCULAR SYSTEM
to the middle of the ascending colon, divides into two branches — a descending
branch, which inosculates with the ileo-colic, and an ascending branch, which
anastomoses with the colica media. These branches form arches, from the
convexity of" which vessels are distributed to the ascending colon. The branches
of this vessel are covered with peritoneum only on their anterior aspect.
The Middle Colic Artery (a. colica media) arises from the upper part of the
concavity of the superior mesenteric, and, passing forward between the layers
of the transverse mesocolon, divides into two branches, the one on the right
side inosculating with the colica dextra; that on the left side, with the colica
sinistra, a branch of the inferior mesenteric. From the arches formed by their
inosculation branches are distributed to the transverse colon. The branches
of this vessel lie between the two layers of the transverse mesocolon.
FIG. 423. — The superior mesenteric artery and its branches.
Blood-supply of the Right Iliac Fossa.— The descending branch of the right colic artery by
anastomosing with the ascending branch of the ileo-colic artery forms a vascular loop. The
union of the descending branch of the ileo-colic artery with the terminal vessel of the superior
mesenteric artery forms another vascular loop. These two loops give off secondary loops, and
from the secondary loops come the vessels which supply the appendix, the caecum, and the
lower end of the ileum. The branch which goes to the appendix is called the appendicular
artery (a. appendicularis). If there is a distinct meso-appendix the artery passes along its
unattached edge. If there is a rudimentary meso-appendix or no meso-appendix the artery
THE ABDOMINAL AORTA
679
usually lies upon the appendix from base to tip beneath the peritoneal covering. In females
the appendix may receive an additional vessel from the ovarian, which vessel lies in the
appendiculo-ovarian ligament.
The Inferior Mesenteric Artery (a. mesenterica inferior] (Figs. 420 and 424).—
The inferior mesenteric artery supplies the descending colon, the sigmoid flexure
of the colon and the greater part of the rectum. It is smaller than the superior
mesenteric, and arises from the left side of the aorta, between one and two inches
above the division of that vessel into the common iliacs. It passes downward
to the left iliac fossa, and then descends between the layers of the mesorectum,
Middle hsemorrhoidal,
Inferior haemorrhoidal.
FIG. 424. — The inferior mesenteric and its branches.
into the pelvis, under the name of the superior hsemorrhoidal artery. It lies at first
in close relation with the left side of the aorta, and then passes as the superior
hsemorrhoidal in front of the left common iliac artery.
In order to expose the inferior mesenteric artery draw the small intestines and mesentery over
to the right side of the abdomen, raise the transverse colon toward the thorax, and divide the
peritoneum covering the front of the aorta.
Branches. — Its branches are — the
Left Colic.
Superior Hsemorrhoidal.
Sigmoid.
680 THE BLOOD -VASCULAR SYSTEM
The Left Colic Artery (a. colica sinistra) passes behind the peritoneum, in
front of the left kidney, to reach the descending colon, and divides into two
branches — an ascending branch, which inosculates with the colica media; and
a descending branch, which anastomoses with the sigmoid artery. From the
arches formed by these inosculations branches are distributed to the descending
colon.
The Sigmoid Arteries (aa. sigmoideae). — As a rule there are two of these vessels,
but may be three. They run obliquely downward across the Psoas muscle to the
sigmoid flexure of the colon, and divide into branches which supply that part of
the intestine, anastomosing above with the left colic, and below with the superior
hsemorrhoidal artery.
The Superior Hemorrhoidal Artery (a. hcemorrhoidalis superior) (Figs. 424 and
427), the continuation of the inferior mesenteric, descends into the pelvis between
the layers of the mesorectum, crossing, in its course, the ureter and left common
.iliac vessels. Opposite the middle of the sacrum it divides into two branches,
which descend one on each side of the rectum, and about five inches from the
arms break up into several small branches, which pierce the muscular coat of the
bowel and run downward, as straight vessels, placed at regular intervals from
each other in the wall of the. gut between its muscular and mucous coat, to the
level of the internal sphincter; here they form a series of loops around the lower
end of the rectum, and communicate with the middle hsemorrhoidal arteries which
are branches of the internal iliac and with the inferior hsemorrhoidal branches
of the internal pudic.
The Suprarenal Artery (a. suprarenalis media) (Fig. 420). — A suprarenal or
•capsular artery arises, one on each side of the aorta, opposite the superior mesenteric
artery. It is a small vessel which passes obliquely upward and outward, over
the crura of the Diaphragm, to the under surface of the suprarenal capsule, to
which it is distributed, anastomosing with capsular branches from the phrenic
and renal arteries. In the adult these arteries are of small size; in the fretus
they are as large as the renal arteries.
The Renal Arteries (aa. renales) (Fig. 420). — The renal arteries are two
large trunks which arise from the sides of the aorta immediately below the superior
mesenteric artery. Each is directed outward across the crus of the Diaphragm,
so as to form nearly a right angle with the aorta. The right is longer than the
left, on account of the position of the aorta; it passes behind the postcava.
The left is somewhat higher than the right. Before reaching the hilum of
the kidney, each artery usually divides into four branches. Two of these vessels
•enter the anterior portion and two the posterior portion of the kidney. There
may be but one renal artery; there may be two, three, four, or five branches. The
greater number of the branches generally lie between the renal vein and ureter, the
vein being in front of the arteries, the ureter behind. The anterior branches supply
three-fourths of the kidney, the posterior supply one-fourth. Each vessel gives
off a small branch to the suprarenal capsule (a. suprarenalis inferior) and branches
to the ureter, ureteral branches, and to the surrounding cellular tissue and muscles,
perirenal branches. Hyrtl, in 1870, pointed out that the renal artery gives off a
branch which divides and supplies the dorsal or posterior portion of the kidney and
its pelvis, and a branch which divides and supplies the ventral or anterior portion
of the kidney and its pelvis. The two circulations are distinct and do not anas-
tomose even at the periphery. Between these two sets of vessels is a bloodless zone,
the exsanguinated renal zone of Hyrtl, which does not correspond to the median
line, but is one-half inch dorsal to the lateral longitudinal renal border. The
ventral or anterior segment is much the larger. In very rare instances the blood-
less zone corresponds to the median line (Kummel). An incision of the middle
third of the kidney exactly at the junction of the two segments does not divide
THE ABDOMINAL AORTA
681
vessels. As the incision approaches either pole there is danger of cutting a branch
(Schecle). Frequently there is a second renal artery, which is given off from the
alxlominal aorta either above or below the renal artery proper, the former being
the more common position. Instead of entering the kidney at the hilum, an
accessory renal artery usually pierces the upper or the lower part of the gland.
The Spermatic Arteries (aa. spermaticae internae) (Fig. 420). — The internal
spermatic arteries are distributed to the testes. They are two slender vessels of
considerable length, which arise from the front of the aorta a little below the renal
arteries. Each artery passes obliquely outward and downward behind the peri-
toneum, resting on the Psoas muscle, the right spermatic lying in front of the
IB
FIG. 425. — The renal artery and the distribution FIG. 426. — A, A, "Brodei's white line;" B, B,
of its branches : A, A, correct incision; B,B, incor- line of best incision for splitting the kidney,
rect incision. (Campbell.) (Campbell.)
postcava, the left behind the sigmoid flexure of the colon. It then crosses obliquely
over the ureter (to which it sends a few branches) and the lower part of the external
iliac artery to reach the internal abdominal ring, through which it passes, afnd
accompanies the other constituents of the spermatic cord along the inguinal canal
to the scrotum, where it becomes tortuous and is prolonged as the testicular artery
(a. testicularis) , which accompanies the vas deferens, anastomosing with the
artery of the vas deferens and is distributed to the epididymis, the back part of
the tunica albuginea, and the substance of the testes. The spermatic artery in the
inguinal canal gives off cremasteric branches to supply the Cremaster muscle.
In the canal and scrotum the artery lies behind the pampiniform plexus and in
front of the vas deferens.
The Ovarian Arteries (aa. ovaricae). — The ovarian arteries (Fig. 428) are the
corresponding arteries in the female to the spermatic in the male. They supply the
ovaries, are shorter than the spermatic, and do not pass out of the abdominal
cavity. The origin and course of the first part of the artery are the same as the
spermatic in the male, but on arriving at the margin of the pelvis the ovarian
irtery passes inward, between the two layers of the broad ligament of the uterus,
682 THE BLOOD-VASCULAR SYSTEM
to be distributed to the ovary, ovarian branches. Branches go to the Fallopian
tube,tubal branches, the ureter, ureteral branches, and the broad ligament, ligamentous
branches. A branch passes on to the side of the uterus and anastomoses with the
uterine arteries, uterine branch. Other offsets are continued along the round
ligament through the inguinal canal, to the integument of the labiurn and groin.
At an early period of foetal life, when the testes or ovaries lie by the side of
the spine below the kidneys, the spermatic or ovarian arteries are short; but as
these organs descend from the abdomen into the scrotum or pelvis, the arteries
become gradually lengthened.
The Inferior Phrenic Arteries (aa. phrenicae inferiores) (Fig. 420). — The inferior
phrenic arteries are two small vessels which present much variety in their origin.
They may arise separately from the front of the aorta, immediately above the
cceliac axis, or by a common trunk, which may spring either from the aorta or
from the creliac axis. Sometimes one is derived from the aorta, and the other
from one of the renal arteries. In only one out of thirty-six cases examined did
these arteries arise as two separate vessels from the aorta. They diverge from
one another across the crura of the Diaphragm, and then pass obliquely upward
and outward upon the under surface of the Diaphragm. The left phrenic passes
behind the oesophagus and runs forward on the left side of the cesophageal
opening. The right phrenic passes behind the postcava, and ascends along the
right side of the aperture for transmitting that vein. Near the back part of the
central tendon each vessel divides into two branches. The internal branch runs
forward to the front of the thorax, supplying the Diaphragm and anastomosing
with its fellow of the opposite side, and with the musculo-phrenic and comes nervi
phrenici branches of the internal mammary. The external branch passes toward
the side of the thorax and inosculates with the intercostal arteries. The internal
branch of the right phrenic gives off a few vessels to the postcava, and the left
one some branches to the oesophagus. Each vessel also sends capsular branches
(rami suprarenales superior] to the suprarenal capsule of its own side. The spleen
on the left side and the liver on the right also receive a few branches from these
vessels.
The Lumbar Arteries (aa. lumbales). — The lumbar arteries are analogous to
the intercostals. They are usually four in number on each side, and arise from
the back part of the aorta, nearly at right angles with that vessel. They pass
outward and backward, around the sides of the bodies of the lumbar vertebrae,
behind the sympathetic nerve and the Psoas magnus muscle, those on the right
side being covered by the postcava, and the two upper ones on each side by the
crura of the Diaphragm. In the interval between the transverse processes of the
vertebrae each artery gives off a dorsal branch.
After the formation of the dorsal branch the artery passes outward, having
a variable relation to the Quadratus lumborum muscle. Most frequently the
first lumbar passes in front of the muscle and the others behind it; sometimes
the order is reversed and the lowest lumbar passes in front of the muscle. At
the outer border of the Quadratus they are continued between the abdominal
muscles, anastomose with branches of the epigastric and internal mammary
in front, the intercostals above, and branches of the ilio-lumbar and circumflex
iliac below. The lumbar arteries are also distributed to the skin of the sides of
the abdomen.
The Dorsal Branch (ramus dorsalis] gives off, immediately after its origin, a
spinal branch, which enters the spinal canal. The dorsal branch then continues
its course backward between the transverse processes, and is distributed to the
muscles and integument of the back, anastomosing with similar branches of the
adjacent lumbar arteries and with the posterior branches of the intercostal
arteries.
THE COMMON ILIAC ARTERIES
683
The Spinal Branch (ramus spinalis) enters the vertebral canal through the inter-
vertebral foramen, to be distributed to the spinal cord and its membranes and
to the bodies of the vertebrae in the same manner as the lateral spinal branches
from the vertebral (see page 640).
The Middle Sacral Artery (a. sacralis media] (Fig. 427).— The middle sacral
artery is a small vessel, which arises from the back part of the aorta just at its bifur-
cation. It descends upon the last lumbar vertebra, and along the middle line of the
front of the sacrum, to the upper part of the coccyx, where it anastomoses with the
lateral sacral arteries, and terminates in a minute branch, which runs down to
the situation of the body described as Luschka's gland. It gives off on each
side opposite the body of the fifth lumbar vertebra a branch known as the
a. lumbalis ima. From the middle sacral artery branches arise which run through
the mesorectum to supply the posterior surface of the rectum. Other branches
are given off on each side, which anastomose with the lateral sacral arteries, and
send off small offsets which enter the anterior sacral foramina.
The artery is the representative of the caudal prolongation of the aorta of
animals, and its lateral branches correspond to the intercostal and lumbar arteries
in the thoracic and lumbar regions.
THE COMMON ILIAC ARTERIES (AA. ILIACAE COMMUTES) (Figs. 420, 427).
The abdominal aorta divides into the two common iliac arteries. The bifurca-
tion usually takes place on the left side of the body of the fourth lumbar ver-
tebra. The common iliac arteries are about two inches in length; diverging
from the termination of the aorta, they pass downward and outward to the margin
of the pelvis, each divides opposite the intervertebral substance, between the last
lumbar vertebra and the sacrum, into two branches, the internal and external
iliac arteries, the latter supplying the lower extremity; the former, the viscera and
parietes of the pelvis.
The right common iliac is somewhat longer than the left, and passes more
obliquely across the body of the last lumbar vertebra. In front of it are the
peritoneum, the small intestines, branches of the sympathetic nerve, and, at its
point of division, the ureter. Behind, it is separated from the fourth and fifth
lumbar vertebrae, with the intervening intervertebral disk, by the two common
iliac veins. On its outer side, it is in relation with the postcava and the right
common iliac vein, above, and the Psoas magnus muscle below.
The left common iliac is in relation, in front, with the peritoneum, branches
of the sympathetic nerve, and the superior hiemorrhoidal artery; and is crossed
at its point of bifurcation by the ureter. It rests on the bodies of the fourth and
fifth lumbar vertebrae, with the intervening intervertebral disk. The left common
iliac vein lies partly on the inner side, and partly beneath the artery; on its outer
side, the artery is in relation with the Psoas magnus muscle.
PLAN OF THE RELATIONS OF THE COMMON ILIAC ARTERIES.
In front.
Peritoneum.
Small intestines.
Sympathetic nerves.
Ureter.
Outer side.
Vena cava.
Right common
iliac vein.
Psoas muscle.
Inner side.
Left common
iliac vein.
In front.
Peritoneum.
Sympathetic nerves.
Superior hsemorrhoidal artery.
Ureter.
Outer side.
Psoas magnus
muscle.
684 THE BLOOD-VASCULAR SYSTEM
Behind. Behind.
Fourth and fifth lumbar vertebrae. Fourth and fifth lumbar vertebrae.
Right and left common iliac veins. Left common iliac vein.
Branches. — The common iliac arteries give off small branches to the perito-
neum, Psoas magnus, ureters, and the surrounding cellular tissue, and occasionally
give origin to the ilio-lumbar or renal arteries.
Peculiarities. — The point of origin varies according to the bifurcation of the aorta. In
three-fourths of a large number of cases the aorta bifurcated either upon the fourth lumbar
vertebra or upon the intervertebral disk between it and the fifth, the bifurcation being, in one
case out of nine below, and in one out of eleven above, this point. In ten out of every thirteen
cases the vessel bifurcated within half an inch above or below the level of the crest of the ilium,
more frequently below than above.
The point of division is subject to great variety. In two-thirds of a large number of cases
it was between the last lumbar vertebra and the upper border of the sacrum, being above that
point in one case out of eight and below it in one case out of six. The left common iliac artery
divides lower down more frequently than the right.
The relative length, also, of the two common iliac arteries varies. The right common iliac
was the longer in sixty-three cases, the left in fifty-two, whilst they were both equal in fifty-
three. The length of the arteries varied in five-sevenths of the cases examined from an inch
and a half to three inches; in about half of the remaining cases the artery was longer and in
the other half shorter, the minimum length being less than half an inch, the maximum four
and a half inches. In two instances the right common iliac has been found wanting, the external
and internal iliacs arising directly from the aorta.
Surface Marking.— Draw a zone around the body opposite the highest part of the crest of
the ilium; in this line take a point half an inch to the left of the middle line. From this draw
two lines to points midway between the anterior superior spines of the ilium and the symphysis
pubis. These two diverging lines will represent the course of the common and external iliac
arteries. Draw a second zone round the body corresponding to the level of the anterior superior
spines of the ilium: the portion of the diverging lines between the two zones will represent the
course of the common iliac artery; the portion below the lower zone, that of the external iliac
artery.
Surgical Anatomy. — The application of a ligature to the common iliac artery may be
required on account of aneurism or hemorrhage implicating the external or internal iliacs.
Now that the surgeon no longer dreads opening the peritoneal cavity, there can be no question
that the easiest and best method of tying the artery is by a transperitoneal route. The abdomen
is opened by an incision in either the semilunar line or the linea alba; the intestines are drawn
to one side and the peritoneum covering the artery divided. The sheath is then opened, and
the needle passed from within outward. On the right side great care must be exercised in
passing the needle, since both the common iliac veins lie behind the artery. After the vessel
has been tied the incision in the peritoneum over the artery should be sutured. Formerly there
were two different methods by which the common iliac artery was tied without opening the
peritoneal cavity: 1, an anterior or iliac incision, by which the vessel is approached more directly
from the front; and 2, a posterior abdominal or lumbar incision, by which the vessel is reached
from behind. If the surgeon select the iliac region, a curved incision, from five to eight inches
in length, according to the amount of fat, is made, commencing just outside the middle of
Poupart's ligament and a finger's breadth above it, and carried outward toward the anterior
superior iliac spine, then upward toward the ribs, and finally curving inward toward the umbili-
cus. The abdominal muscles and transversalis fascia are divided, and the peritoneum raised
upward and inward until the Psoas is reached. The artery will be found on the inner side of
this muscle, and is to be cleared with a director, especial care being taken on the right side, as
here the common iliac veins lie behind the artery. The aneurism needle is to be passed from
within outward. But if the aneurismal tumor should extend high up in the abdomen, along
the external iliac, it is better to select the posterior or lumbar route, making an incision partly in
the abdomen, partly in the loin. The incision is commenced at the anterior extremity of the
last rib, proceeding directly downward to the ilium ; it is then curved forward along the crest of
the ilium and a little above it to the anterior superior spine of that bone. The abdominal mus-
cles having been cautiously divided in succession, the transversalis fascia must be carefully cut
through, and the peritoneum, together with the ureter, separated from the artery and pushed
aside; the sacro-iliac articulation must then be felt for, and upon it the vessel will be felt pulsat-
ing, and may be fully exposed in close connection with the accompanying vein. On the right
side both common iliac veins, as well as the postcava, are in close connection with the artery,
and must be carefully avoided. On the left side the vein usually lies on the inner side and
behind the artery; but it occasionally happens that the two common iliac veins are joined on
'/'///; IXTKRNAL ILIAC ARTERY 685
the left instead of the right side, which would add much to the difficulty of an operation in
such a case. The common iliac artery may be so short that danger may be apprehended from
secondary hemorrhage it' a ligature is applied to it. It would be preferable, in such a case, to
tie both the external and internal iliacs near their origin.
Collateral Circulation. — The principal agents in carrying on the collateral circulation after
the application of a ligature to the common iliac are — the anastomoses of the hsemorrhoidal
1) ranches of the internal iliac with the superior hsemorrhoidal from the inferior mesenteric; the
anastomoses of the uterine and ovarian arteries and of the vesical arteries of opposite sides; of
the lateral sacral with the middle sacral artery; of the epigastric with the internal mammary,
inferior intercostal, and lumbar arteries; of the circumflex iliac with the lumbar arteries; of the
ilio-lumbar with the last lumbar artery; of the obturator artery, by means of its pubic branch,
with the vessel of the opposite side and with the deep epigastric.
Compression of the Common Iliac Arteries. — The common iliac arteries may be com-
pressed by Davy's lever. The instrument consists of a gum-elastic tube about two feet long,
in which fits a round wrooden "lever" considerably longer than the tube. A small quantity
of olive oil having been injected into the rectum, the gum-elastic tube, softened in hot w^ater,
is passed into the bowel sufficiently far to permit its pressing upon the common iliac artery
as it lies in the groove between the last lumbar vertebra and the Psoas muscle. The wooden
lever is then inserted into the tube, and the projecting end carried toward the opposite thigh
and raised, when it acts as a lever of the first order, the anus being the fulcrum. In cases where
the niesorectum is abnormally short it may be impossible, without unjustifiable force, to com-
press the artery on the right side. In amputation of the hip-joint the common iliac can be
compressed most certainly and safely by opening the abdomen and compressing the vessel by
means of the fingers against the Psoas muscle (McBurney's method).
The Internal Iliac Artery (Figs. 420, 427).
The internal iliac or hypogastric artery (a. hypogastrica) supplies the walls and
viscera of the pelvis, the generative organs, and inner side of the thigh. It is
a short thick vessel, smaller in the adult than the external iliac, and about an
inch and a half in length. It arises at the point of bifurcation of the common
iliac, and, passing downward to the upper margin of the great sacro-sciatic
foramen, divides into two large trunks, an anterior, and posterior; from its anterior
division a partially obliterated cord, a part of the fcetal hypogastric artery, extends
forward to the bladder.
Relations. — In front, with the ureter, which is between the artery and the
peritoneum. Behind, with the internal iliac vein, the lumbo-sacral cord, and
Pyriformis muscle. By its outer side, near its origin, with the Psoas magnus muscle.
PLAN OF THE RELATIONS OF THE INTERNAL ILIAC ARTERY.
In front.
Peritoneum.
Ureter.
Outer side.
Psoas magnus.
Behind.
Internal iliac vein.
Lumbo-sacral cord.
Pyriformis muscle.
In the foetus the hypogastric artery is twice as large as the external iliac, and
appears to be the continuation of the common iliac. Instead of dipping into
the pelvis, it passes forward to the bladder, and ascends along the sides of that
viscus to its summit, to which it gives branches; it then passes upward along the
" >ack part of the anterior wall of the abdomen to the umbilicus, converging
toward its fellow of the opposite side. Having passed through the umbilical
686
THE BLOOD-VASCULAR SYSTEM
opening, the two arteries twine round the umbilical vein in the umbilical cord,
and ultimately ramify in the placenta. The portion of the vessel within the
abdomen is called the hypogastric artery; the portion external to that cavity, the
umbilical artery.
At birth, when the placental circulation ceases, the upper portion of the hypo-
gastric artery, extending from the summit of the bladder to the umbilicus, con-
tracts, and ultimately dwindles to a solid fibrous cord; but the lower portion,
extending from its origin (in what is now the internal iliac artery) for about an
inch and a half to the wall of the bladder, arid thence to the summit of that organ,
is not totally impervious, though it becomes considerably reduced in size, and
serves to convey blood to the bladder under the name of the superior vesical
artery.
Ileo-lumbar.
-Gluteal.
FIG. 427. — Arteries of the pelvis.
Peculiarities as Regards Length. — In two-thirds of a large number of cases the length of
the internal iliac varied between an inch and an inch and a half; in the remaining third it was
more frequently longer than shorter, the maximum length being three inches, the minimum
half an inch.
The lengths of the common and internal iliac arteries bear an inverse proportion to each
other, the internal iliac artery being long when the common iliac is short, and vice versa.
As' Regards its Place of Division. — The place of division of the internal iliac varies
between the upper margin of the sacrum and the upper border of the sacro-sciatic foramen.
The arteries of the two sides in a series of cases often differed in length, but neither seemed
constantly to exceed the other.
THE INTERNAL ILIAC ARTERY 087
Surgical Anatomy.— The application of a ligature to the internal iliac artery may be
required in cases of aneurism or hemorrhage affecting one of its branches. The vessel may be
secured by making an incision through the abdominal parietes in the iliac region in a direction
and to an extent similar to that for securing the common iliac; the transversalis fascia having
been cautiously divided, and the peritoneum pushed inward from the iliac fossa toward the
pelvis, the finger may feel the pulsation of the external iliac at the bottom of the wound, and by
tracing this vessel upward the internal iliac is arrived at, opposite the sacro-iliac articulation. It
should be remembered that the vein lies behind and on the right side, a little external to the
artery, and in close contact with it; the ureter and peritoneum, which lie in front, must also be
avoided. The degree of facility in applying a ligature to this vessel will mainly depend upon
the length of the vessel. It has been seen that in the great majority of the cases examined the
artery was short, varying from an inch to an inch and a half; in these cases the artery is deeply
seated in the pelvis; when, on the contrary, the vessel is longer, it is found partly above that
cavity. If the artery is very short, as occasionally happens, it would be preferable to apply a
ligature to the common iliac or to both the external and internal iliacs at their origin.
A better method of tying the internal iliac artery is by an abdominal section in the median
line and reaching the vessel through the peritoneal cavity. This plan has been advocated by
Dennis, of Xew York, on the following grounds: (1) It in no way increases the danger of the
operation; (2) it prevents a series of accidents which have occurred during ligature of the artery
by the older methods; (3) it enables the surgeon to ascertain the exact extent of disease in the
main arterial trunk, and select his spot for the application of the ligature; and (4) it occupies
much less time.
Collateral Circulation. — In Professor Owen's dissection of a case in which the internal
iliac artery had been tied by Stevens ten years before death for aneurism of the sciatic artery,
the internal iliac was found impervious for about an inch above the point where the ligature had
been applied, but the obliteration did not extend to the origin of the external iliac, as the ilio-
lumbar artery arose just above this point. Below the point of obliteration the artery resumed
its natural diameter, and continued so for half an inch, the obturator, lateral sacral, and gluteal
arising in succession from the latter portion. The obturator artery was entirely obliterated.
The lateral sacral artery was as large as a crow's quill, and had a very free anastomosis with the
artery of the opposite side and with the middle sacral artery. The sciatic artery was entirely
obliterated as far as its point of connection with the aneurismal tumor, but on the distal side of
the sac it was continued down along the back of the thigh nearly as large in size as the femoral,
being pervious about an inch below the sac by receiving an anastomosing vessel from the pro-
funda.1 The circulation was carried on by the anastomoses of the uterine and ovarian arteries;
of the opposite vesical arteries; of the hemorrhoidal branches of the internal iliac with those
from the inferior mesenteric; of the obturator artery, by means of its pubic branch, with the
vessel of the opposite side and with the epigastric and internal circumflex; of the circumflex
and perforating branches of the profunda femoris with the sciatic; of the gluteal with the poste-
rior branches of the sacral arteries; of the ilio-lumbar with the last lumbar; of the lateral sacral
with the middle sacral; and of the circumflex iliac with the ilio-lumbar and gluteal.
Branches (Fig. 427). — The branches of the internal iliac are:
From the Anterior Trunk. From the Posterior Trunk,
Superior Vesical. Ilio-lumbar.
Middle Vesical. Lateral Sacral.
Inferior Vesical. Gluteal.
Middle Hsemorrhoidal.
Obturator.
Internal Pudic.
Sciatic.
Uterine.
Vaginal.
The Superior Vesical (a. vesicalis superior] (Fig. 427), is that part of the foetal
hypogastric artery, which remains pervious after birth. It extends to the side of
the bladder, distributing numerous branches to the apex and body of the organ.
From one of these a slender vessel is derived which accompanies the vas deferens
in its course to the testis, where it anastomoses with the spermatic artery. This is
the artery of the vas deferens. Other branches supply the ureter.
1 Medico-Chirurgical Transactions, vol. xvi.
688 THE BLOOD- VASCULAR SYSTEM
The Middle Vesical (a. vesicalis medialis) (Fig. 427), usually a branch of the
superior, is distributed to the base of the bladder and under surface of the vesiculse
seminales.
The Inferior Vesical (a. vesicalis inferior} (Fig. 427) arises from the anterior
division of the internal iliac, frequently in common with the middle hemorrhoidal,
and is distributed to the base of the bladder, the prostate gland, and vesiculse
seminales. The branches distributed to the prostate communicate with the
corresponding vessel of the opposite side.
The Middle Hsemorrhoidal Artery (a. hcemorrhoidalis media) (Fig. 427)
usually arises together with the preceding vessel. It supplies the anus and
parts outside the rectum, anastomosing with the other hemorrhoidal arteries.
The Uterine Artery (a. uterina) (Fig. 428) passes inward from the anterior
trunk of the internal iliac to the neck of the uterus. Ascending in a tortuous course
on the side of this viscus, between the layers of the broad ligament, it distributes
branches to its substance and to the round ligament and the Fallopian tube (ramus
tubarius), anastomosing, near its termination, with the ovarian artery. It gives a
branch to the ovary (ramus ovarii), which anastomoses with a branch from the
ovarian branches to the cervix uteri (cervico-uteri) , and a branch which descends
Branches to tube.
Branches to fnndus.
Ovarian artery.
Branch to round ligament.
ROUND LIGAMENT.
Uterine artery.
Arteries of cervix.
Vaginal arteries.
FIG. 428. — The arteries of the internal organs of generation of the female, seen from behind. (After Hyrtl.)
on the vagina (cervico-vaginal) , and, joining with branches from the vaginal
arteries, form a median longitudinal vessel both in front and behind; these descend
on the anterior and posterior surfaces of the vagina, and are named the azygos
arteries of the vagina.
The Vaginal Artery (a. vaginalis] is analogous to the inferior vesical in the
male; it descends upon the vagina, supplying its mucous membrane, and sending
branches to the neck of the bladder and contiguous part of the rectum. There
may be several vaginal arteries. The vaginal artery assists in forming the azygos
arteries of the vagina, which are anterior and posterior vessels, running longi-
tudinally, and due to anastomoses of the branches of the vaginal from each side
and the cervico-vaginal artery.
THE INTERNAL ILIAC ARTERY 689
Luschka, Hyrtl, Waldeyer, Robinson, and others, instead of describing the
ovarian and uterine arteries as two distinct vessels, regard them as constituting
the chief parts of one vessel, the arteria uterina ovarica. What has been called " the
circle of Robinson" is composed of a spiral segment (the arteria uterina ovarica),
with a portion of the abdominal aorta, common iliacs, and internal iliacs.
Robinson1 has made a careful study of this vascular circle; he shows that
it is of great importance in certain surgical procedures, and that its remark-
able "capacity for extension" saves it from damage when the uterus is enormously
distended by pregnancy, or when it is "drawn through the pudendum with trac-
tion forceps for palpation, inspection, or repair."
The author just quoted says further that the utero-ovarian artery has three
origins, because it develops from the Wolffian body: The ovarian segment arises
from the abdominal aorta. The uterine segment arises from the anterior branch
of the internal iliac artery. The artery of the round ligament arises from the deep
epigastric. The arteria uterina ovarica artery secures nutrition to the uterus by
bringing blood from three sources. It is spiral throughout its entire course, in
certain parts is convoluted or looped, and it is accompanied by the pampiniform
plexus of veins.
The three origins of this vessel are freely united by anastomoses, and rami
laterales are given off, which unite the bilateral vessels in the median line. Robin-
son describes three bifurcations of the utero-ovarian artery. The distal bifurcation,
which is "about midway between the uterus and the pelvic wall," and forms an
acute angle with the main vessel. This bifurcation indicates the point of division
of the external from the internal genitals. The cervico-vaginal artery supplies the
external genitals. The proximal bifurcation marks the situation of the ovary. The
artery bifurcates at an acute angle into two branches to supply the ovary and
Fallopian tube. The middle bifurcation consists of (1) the division of the uterine
segment at the angle formed by the uterus and oviduct ("forming the ramus ovi-
ductus and ramus ovarii") and (2) "the bifurcation of the ramus oviductus form-
ing the ramus oviductus and the ramus ligamenti teretis, or the segment of the
round ligament.'''2
Surgical Anatomy. — As pointed out by Robinson, the source of bleeding after vaginal hys-
terectomy is usually the torn and undamped cervico-vaginal artery.
As previously pointed out, the spiral and convoluted shape of the utero-ovarian artery allows
the uterus, ovary, and tube to be drawn into the vagina without injury to the vessels. Robinson
points out that in vaginal hysterectomy the genital circle is not divided and only the rami later-
ales which go to the uterus are cut, the ovaries retaining a normal blood-supply and continuing
to functionate.
The Obturator Artery (a. obturatoria) (Fig. 427) usually arises from the anterior
trunk of the internal iliac; frequently from the posterior. It passes forward, below
the brim of the pelvis, to the upper part of the obturator foramen, accompanied by
the obturator nerve and vein, and, escaping from the pelvic cavity through a short
canal formed by a groove on the under surface of the ascending ramus of the os
pubis and the arched border of the obturator membrane, it divides into an internal
and external branch. In the pelvic cavity this vessel lies upon the pelvic fascia,
beneath the peritoneum, and a little below the obturator nerve.
Branches. — Within the pelvis, the obturator artery gives off an iliac branch
(ramus iliacus) to the iliac fossa, which supplies the bone and the Iliacus muscle,
and anastomoses with the ilio-lumbar artery; a vesical branch (ramus vesicalis),
which runs backward to supply the bladder; and a pubic branch (ramus pubicus),
which is given off from the vessel just before it leaves the pelvic cavity. This
branch ascends upon the back of the os pubis, communicating with offsets from
1 Robinson. The Utero-ovarian Artery. 2 Ibid.
44
690 THE BLOOD-VASCULAR SYSTEM
the deep epigastric artery and with the corresponding vessel of the opposite
side. It is placed on the inner side of the femoral ring. External to the pelvis,
the obturator artery divides into an internal and an external branch, which are
deeply situated beneath the Obturator externus muscle.
The Internal Branch (ramus anterior] curves downward along the inner margin
of the obturator foramen, lying beneath the Obturator externus muscle; it dis-
tributes branches to the Obturator externus, Pectineus, Adductors, and Gracilis,
and anastomoses with the external branch and with the internal circumflex artery.
The External Branch (ramus posterior) curves round the outer margin of the
obturator foramen, also lying beneath the Obturator externus muscle, to the space
between the Gemellus inferior and Quadratus femoris, where it divides into two
branches: one, smaller, courses inward around the lower margin of the foramen
and anastomoses with the internal branch and with the internal circumflex; the
other inclines outward in the groove below the acetabulum (a. acetabulis) , and
supplies the muscles attached to the tuberosity of the ischium and anastomoses
with the sciatic artery. It sends a branch to the hip-joint through the cotyloid
notch, which ramifies on the round ligament as far as the head of the femur.
Peculiarities (Fig. 429).— In two out of every three cases the obturator arises from the
internal iliac ; in one case in three and a half from the epigastric ; and in about one in seventy-
two cases by two roots from both vessels. It arises in about the same proportion from the
external iliac artery. The origin of the obturator from the epigastric is not commonly found
on both sides of the same body.
FIG. 429. — Variations in origin and course of the obturator artery.
When the obturator artery arises at the front of the pelvis from the epigastric, it descends
almost vertically to the upper part of the obturator foramen. The artery in this course usually
lies in contact with the external iliac vein and on the outer side of the femoral ring (Fig. 429, A);
in such cases it would not be endangered in the operation for femoral hernia. Occasionally,
however, it curves inward along the free margin of Gimbernat's ligament (Fig. 429, B), and
under such circumstances would almost completely encircle the neck of a hernial sac (supposing
a hernia to exist in such a case), and would be in great danger of being wounded if an operation
was performed.
The Internal Pudic Artery (a. pudenda interna) (Figs. 427, 430, and 431) is the
smaller of the two terminal branches of the anterior trunk of the internal iliac,
and supplies the external organs of generation. Though the course of the artery
is the same in the two sexes, the vessel is much smaller in the female than in the
male, and the distribution of its branches somewhat different. The description of
its arrangement in the male will first be given, and subsequently the differences
which it presents in the female will be mentioned.
The Internal Pudic Artery in the Male passes downward and outward to the
lower border of the great sacro-sciatic foramen, and emerges from the pelvis
between the Pyriformis and Coccygeus muscles: it then crosses the spine of the
ischium and re-enters the pelvis through the lesser sacro-sciatic foramen. The
artery now crosses the Obturator internus muscle along the outer wall of the ischio-
rectal fossa, being situated about an inch and a half above the lower margin of the
ischial tuberosity. It is here contained in a sheath of the obturator fascia, and
THE INTERNAL ILIAC ARTERY 691
gradually approaches the margin of the ramus of the ischium, along which it passes
forward and upward, pierces the base of the superficial layer of the triangular
ligament of the urethra, and runs forward along the inner margin of the ramus of
the os pubis, and divides into its two terminal branches, the dorsal artery of the
penis and the artery of the corpus cavernosum.
Relations. — In the first part of its course, within the pelvis, it lies in front of
the Pyriformis muscle and sacral plexus of nerves, and the sciatic artery, and
on the outer side of the rectum (on the left side). As it. crosses the spine of the
ischium it is covered by the Gluteus maximus and overlapped by the great sacro-
sciatic ligament. Here the obturator nerve lies to the inner side and the nerve
to the Obturator internus to the outer side of the vessel. In the pelvis it lies on
the outer side of the ischio-rectal fossa, upon the surface of the Obturator internus
muscle, contained in a fibrous canal, the canal of Alcock, formed by the splitting of
the obturator fascia. It is accompanied by the pudic veins and the pudic nerve.
Peculiarities.— The internal pudic is sometimes smaller than usual, or fails to give off one
or two of its usual branches; in such cases the deficiency is supplied by branches derived from
an additional vessel, the accessory pudic, which generally arises from the internal pudic artery
before its exit from the great sacro-sciatic foramen. It passes forward along the lower part of
the bladder and across the side of the prosta*'1 gland to the root of the penis, where it perforates
the triangular ligament and gives off the branches usually derived from the pudic artery. The
deficiency most frequently, met with is that in which the internal pudic ends as the artery of the
bulb, the artery of the corpus cavernosum and arteria dorsalis penis being derived from the
accessory pudic. Or the pudic may terminate as the superficial perineal, the artery of the bulb
being derived, with the other two branches, from the accessory vessel. Occasionally the acces-
sory pudic artery is derived from one of the other branches of the internal iliac, most frequently
the inferior vesical or the obturator.
Surgical Anatomy. — The relation of the accessory pudic to the prostate gland and urethra
is of the greatest interest in a surgical point of view, as this vessel is in danger of being wounded
in the operation of lateral lithotomy. The student should also study the position of the internal
pudic artery and its branches, when running a normal course with regard to the same operation.
The superficial and the transverse perineal arteries are, of necessity, divided in this operation,
but the hemorrhage from these vessels is seldom excessive; should a ligature be required, it
can readily be applied on account of their superficial position. The artery of the bulb may
be divided if the incision be carried too far forward, and injury of this vessel may be attended
with serious or even fatal consequences. The main trunk of the internal pudic artery may be
wounded if the incision be carried too far outward; but, being bound down by the strong obtura-
tor fascia and under cover of the ramus of the ischium, the accident is not very likely to occur
unless the vessel runs an anomalous course.
Branches. — The branches of the internal pudic artery are — the
Muscular. Transverse Perineal.
Inferior FLemorrhoidal. Artery of the Bulb.
Superficial Perineal. Artery of the Corpus Cavernosum.
Dorsal Artery of the Penis.
The Muscular Branches consist of two sets — one given off in the pelvis, the
other as the vessel crosses the ischial spine. The former are several small offsets
which supply the Levator ani, the Obturator internus, the Pyriformis, and the
Coccygeus muscles. The branches given off outside the pelvis are distributed to
the adjacent part of the Gluteus maximus and External rotator muscles. They
anastomose with branches of the sciatic artery.
The Inferior Haemorrhoidal Artery (a. hcemorrhoidalis inferior} arises from
the internal pudic as it passes above the tuberosity of the ischium. Crossing the
ischio-rectal fossa it is distributed by two or three terminal branches to the
muscles and integument of the anal region. Instead of one inferior hemor-
rhoidal artery two or three small vessels may arise from the internal pudic.
The Superficial Perineal Artery (a. perinei)(¥\g. 430) supplies the scrotum and the
muscles and integument of the perinseum. It arises from the internal pudic in front
692
THE BLOOD- VASCULAR SYSTEM
of the preceding branches, and turns upward, crossing either over or under the
Transversus perinei superficialis muscle, and runs forward, parallel to the pubic
arch, in the interspace between the Accelerator urinse and Erector penis muscles,
both of which it supplies, and is finally distributed to the skin and dartos of the
scrotum. In its passage through the perinseum it lies beneath the superficial
perineal fascia.
The Transverse Perineal Artery is a small branch which arises either from the
internal pudic or from the superficial perineal artery as it crosses the Transversus
perinsei muscle. It runs transversely inward along the cutaneous surface of the
Transversus perinei superficialis muscle, which it supplies, as well as the structures
between the anus and bulb of the urethra, and anastomoses with the like vessel
of the opposite side.
Transversuit perinei
superficialis.
GREAT SACRO-
SCIATIC LIGAMENT
Superficial perineal artery.
Superficial perineal nerve*
Internal pudic nerve.
Internal pudic artery.
Fio. 430. — The superficial muscles and vessels of the perinseum.
The Artery of the Bulb (a. bulbi urethrae) is a large but very short vessel which
arises from the internal pudic between the two layers of the triangular ligament,
and, passing nearly transversely inward, between the fibres of the Compressor
urethrse muscle, it pierces the bulb of the urethra, which it supplies, and con-
tinues anteriorly in the corpus spongiosum to the glans and anastomoses with its
fellow of the opposite side. It gives off a small branch which descends to supply
Cowper's gland.
Surgical Anatomy. — This artery is of considerable importance in a surgical point of view,
as it is in danger of being wounded in the median or the lateral operation of lithotomy— an
accident usually attended in the adult with alarming hemorrhage. The vessel is sometimes
very small, occasionally wanting, or even double. It sometimes arises from the internal pudic
earlier than usual, and crosses the perinseum to reach the back part of the bulb. In such a case
the vessel could hardly fail to be wounded in the performance of the lateral operation of lith-
otomy. If, on the contrary, it should arise from an accessory pudic, it lies more forward than
usual and is out of danger in the operation.
The Artery of the Corpus Cavernosum (a. profunda penis'), one of the terminal
branches of the internal pudic, arises from that vessel while it is situated between
THE INTERNAL ILIAC ARTERY
693
the two layers of the triangular ligament; it pierces the superficial layer, and,
entering the crus penis obliquely, it runs forward in the centre of the corpus
cavernosum, to which its branches are distributed.
The Dorsal Artery of the Penis (a. dorsalis penis) ascends between the crus and
pubic symphysis, and, piercing the triangular ligament, passes between the two
layers of the suspensory ligament
of the penis, and runs forward
on the dorsum of the penis to the
glans, where it divides into iwo
branches which supply the glans
and prepuce. On the dorsum
of the penis it lies immediately
beneath the integument, parallel
with the dorsal vein and the
corresponding artery of the op-
posite side. It supplies the in-
tegument and fibrous sheath of
the corpus cavernosum, sending
branches through the sheath to
anastomose with the preceding
vessel.
The Internal Pudic Artery in
the Female is smaller than in the
male. Its origin and course are
similar, and there is consider-
able analogy in the distribution
of its branches. The superficial
perineal artery supplies the labia
pudendi; the artery of the bulb
supplies the bulbi vestibuli and
the erectile tissue of the vagina;
the artery of the corpus cav-
ernosum (a. profunda clitoridis)
supplies the cavernous body of
the clitoris; and the arteria
dorsalis clitoridis supplies the
dorsum of that organ, and ter-
minates in the glans and in the
membranous fold corresponding
to the prepuce of the male.
The Sciatic Artery (a. glutaea
inferior) (Fig. 431), the larger of
the two terminal branches of the
anterior trunk of the internal
iliac, is distributed to the mus-
cles at the back of the pelvis.
It passes down to the lower part
of the great sacro-sciatic fora-
men behind the internal pudic artery, resting on the sacral plexus of nerves and
Pyriformis muscle, and escapes from the pelvis through this foramen between the
Pyriformis and Coccygeus. It then descends in the interval between the tro-
chanter major and tuberosity of the ischium, accompanied by the sciatic nerves,
and covered by the Gluteus maximus, and is continued down the back of the thigh
supplying the skin, and anastomosing with branches of the perforating arteries.
Termination
of internal
circumflex.
Superior
perforating.
Middle
perforating.
Inferior
perforating.
Termination of
profunda.
.Superior muscular.
Superior external
articular.
Inferior muscular.
FIG. 431. — The arteries of the gluteal and posterior femoral
regions.
Superior internal
articular.
694 THE BLOOD- VASCULAR SYSTEM
Within the pelvis it distributes branches to the Pyriformis, Coccygeus, and
Levator ani muscles; some hemorrhoidal branches, which supply the rectum, and
occasionally take the place of the middle hemorrhoidal artery; and vesical
branches to the base and neck of the bladder, vesiculse seminales, and prostate
gland. External to the pelvis it gives off the following branches:
Coccygeal. Muscular.
Inferior Gluteal. Anastomotic.
Comes Nervi Ischiadici. Articular.
The Coccygeal Branch runs inward, pierces the great sacro-sciatic ligament, and
supplies the Glutetis maximus, the integument, and other structures on the back
of the coccyx.
The Inferior Gluteal Branches, three or four in number, supply the Gluteus
maximus muscle, anastomosing with the gluteal artery in the substance of the
muscle.
The Comes Nervi Ischiadici (a. comitans n, ischiadici} is a long, slender vessel
which accompanies the great sciatic nerve for a short distance; it then penetrates
it and runs in its substance to the lower part of the thigh.
The Muscular Branches supply the Gluteus maximus, anastomosing with the
gluteal artery in the substance of the muscle; the external rotators, anastomosing
with the internal pudic artery; and the muscles attached to the tuberosity of the
ischium, anastomosing with the external branch of the obturator and the internal
circumflex arteries.
The Anastomotic Artery is directed downward across the external rotators and
assists in forming the so-called crucial anastomosis by anastomosing with the
superior perforating and the internal and external circumflex arteries.
The Articular Branch, generally derived from the anastomotic, is distributed to
the capsule of the hip-joint.
The Ilio-lumbar Artery (a. ilio lumbalis), given off from the posterior trunk
of the internal iliac, turns upward and outward between the obturator nerve and
lumbo-sacral cord, to the inner margin of the Psoas muscle, behind which it divides
into a lumbar and an iliac branch.
The Lumbar Branch (ramus lumbalis) supplies the Psoas and Quadratus lum-
borum muscles, anastomosing with the last lumbar artery, and sends a small
spinal branch (ramus spinalis) through the intervertebral foramen, between the last
lumbar vertebra and the sacrum, into the spinal canal, to supply the cauda equina.
The Iliac Branch (ramus iliacus} descends to supply the Iliacus muscle; some
offsets, running between the muscle and the bone, anastomose with the iliac branch
of the obturator; one of these enters an oblique canal to supply the diploe, whilst
others run along the crest of the ilium, distributing branches to the Gluteal and
Abdominal muscles, and anastomose in their course with the gluteal, circumflex
iliac, and external circumflex arteries.
The Lateral Sacral Artery (a. sacralis lateralis) (Fig. 427) runs downward.
It may be single, but usually there are two on each side, the superior and inferior
divisions.
The Superior Division, which is of large size, passes inward, and, after anastomos-
ing with branches from the middle sacral, enters the first or second anterior sacral
foramen, gives spinal branches (rami spinalis) to the contents of the sacral canal,
and, escaping by the corresponding posterior sacral foramen, supplies the skin
and muscles on the dorsum of the sacrum, anastomosing with the gluteal.
The Inferior Division passes obliquely across the front of the Pyriformis muscle
and sacral nerves to the inner side of the anterior sacral foramina, descends on the
front of the sacrum, and anastomoses over the coccyx with the middle sacral and
opposite lateral sacral arteries. In its course it gives off spinal branches which
THE INTERNAL ILIAC ARTERY 695
enter the anterior sacral foramina (rand spinales) ; these, after supplying the con-
tents of the sacral canal, escape by the posterior sacral foramina, and are dis-
tributed to the muscles and skin on the dorsal surface of the sacrum, anastomosing
with the gluteal.
The Gluteal Artery (a. glutaea superior) (Fig. 431) is the largest branch of
the internal iliac, and appears to be the continuation of the posterior division of
that vessel. It is a short thick trunk, which passes out of the pelvis above the
upper border of the Pyriformis muscle, and immediately divides into a superficial
and deep branch. Within the pelvis it gives off a few muscular branches to the
Iliacus, Pyriformis, and Obturator internus, and, just previous to emerging from
that cavity, a nutrient artery, which enters the ilium.
The Superficial Branch passes beneath the Gluteus maximus and divides into
numerous branches, some of which supply that muscle, whilst others perforate its
tendinous origin, and supply the integument covering the posterior surface of the.
sacrum, anastomosing with the posterior branches of the sacral arteries.
The Deep Branch runs between the Gluteus medius and minimus, and sub-
divides into two. Of these, the superior division (ramus superior), continuing the
original course of the vessel, passes along the upper border of the Gluteus minimus
to the anterior superior spine of the ilium, anastomosing with the circumflex iliac
and ascending branches of the external circumflex artery. The inferior division
(ramus inferior) crosses the Gluteus minimus obliquely to the trochanter major,
distributing branches to the Glutei muscles, and inosculates with the external
circumflex artery. Some branches piece the Gluteus minimus to supply the hip-
joint.
Surface Marking. — The position of the three main branches of the internal iliac, the
sciatic, internal pudic, and gluteal, which may occasionally be the object of surgical interference,
is indicated on the surface in the following way: A line is to be drawn from the posterior supe-
rior iliac spine to the posterior superior angle of the great trochanter, with the limb slightly
flexed and rotated inward: the point of emergence of the gluteai artery from the upper part of
the sciatic notch will correspond with the junction of the upper with the middle third of this
line. A second line is to be drawn from the same point to the outer part of the tuberosity of
the ischium; the junction of the lower with the middle third marks the point of emergence of
the sciatic and pudic arteries from the great sciatic notch.
Surgical Anatomy. — Any of these three vessels may require ligating for a wound or for
aneurism, which is generally traumatic. The gluteal artery is ligated by turning the patient
two-thirds over on his face and making an incision from the posterior superior spine of the ilium
to the upper and posterior angle of the great trochanter. This must expose the Gluteus maxi-
mus muscle, and its fibres are to be separated through the whole thickness of the muscle and
pulled apart with retractors. The contiguous margins of the gluteus medius and Pyriformis
are now to be separated from each other, and the artery will be exposed emerging from the
sciatic notch. In ligation of the sciatic artery, the incision should be made parallel with that
for ligation of the gluteal, but one inch and a half lower down. After the fibres of the Gluteus
maximus have been separated, the vessel is to be sought for at the lower border of the Pyri-
formis; the great sciatic nerve, which lies just above it, forming the chief guide to the artery.
The internal pudic can be reached through the incision used to reach the sciatic.
The External Iliac Artery (A. Hiaca Externa) (Fig. 427).
The external iliac artery is larger in the adult than is the internal iliac. It
passes obliquely downward and outward along the inner border of the Psoas
muscle, from the bifurcation of the common iliac to Poupart's ligament, where
it enters the thigh and becomes the femoral artery.
Relations. — In front, with the peritoneum, subperitoneal areolar tissue or Aber-
nethy's fascia, the termination of the ileum on the right side, and the sigmoid flexure
on the left, and a thin layer of fascia derived from the iliac fascia, which surrounds
the artery and vein. At its origin it is occasionally crossed by the ureter. The
spermatic vessels descend for some distance upon it near its termination, and it is
696 THE BLOOD-VASCULAR SYSTEM
crossed in this situation by the genital branch of the genito-femoral nerve and the
deep circumflex iliac vein; the vas deferens curves down along its inner side. Be-
hind, it is in relation with the external iliac vein, which, at Poupart's ligament, lies at
its inner side; on the left side the vein is altogether internal to the artery. Exter-
nally, it rests against the Psoas muscle, from which it is separated by the iliac
fascia. The artery rests upon this muscle, near Poupart's ligament. Numerous
lymphatic vessels and glands are found lying on the front and inner side of the
vessel.
PLAN OF THE RELATIONS OF THE EXTERNAL ILIAC ARTERY.
Near
Poupart's
Ligament.
In front.
Peritoneum, intestines, and fascia.
Lymphatic vessels and glands.
Spermatic vessels.
Genito-femoral nerve (genital branch).
Deep circumflex iliac vein.
Outer side. / \ Inner side.
Psoas magnus. Eiifacnal External iliac vein and vas deferens
Iliac fascia. V J near Poupart's ligament.
Behind.
External iliac vein.
Psoas magnus.
Surface Marking. — The surface line indicating the course of the external iliac artery has
been already given (see page 684).
Surgical Anatomy. — The application of a ligature to the external iliac may be required in
cases of aneurism of the femoral artery or for a wound of the artery. This vessel may be
secured in any part of its course, excepting near its upper end, which is to be avoided on account
of the proximity of the great stream of blood in the internal iliac, and near its lower end, which
should also be avoided, on account of the proximity of the deep epigastric and circumflex iliac
vessels. The patient having been placed in the supine position, an incision should be made,
commencing below at a point about three-quarters of an inch above Poupart's ligament, and
a little external to its middle, and running upward and outward, parallel to Poupart's ligament,
to a point one inch internal and one inch above the anterior superior spine of the ilium. When
the artery is deeply seated more room will be required, and may be obtained by curving the
incision from the point last named inward toward the umbilicus for a short distance. Another
mode of ligating the vessel is the plan advocated by Sir Astley Cooper, by making an incision
close to Poupart's ligament from about half an inch outside of the external abdominal ring to
one inch internal to the anterior superior spine of the ilium. This incision, being made in the
course of the fibres of the aponeurosis of the external oblique, is less likely to be followed by a
ventral hernia, but there is danger of wounding the epigastric artery, and only the lower end
of the vessel can' be ligated. Abernethy, who first tied this artery, made his incision in the
course of the vessel. The abdominal muscles and transversalis fascia having been cautiously
divided, the peritoneum should be separated from the iliac fossa and raised toward the pelvis;
and on introducing the finger to the bottom of the wound, the artery may be felt pulsating along
the inner border of the Psoas muscle. The external iliac vein is generally found on the inner
side of the artery, and must be cautiously separated from it by the finger-nail or handle of the
knife, and the aneurism needle should be introduced on the inner side, between the artery and
the vein.
Ligation of the external iliac artery has recently been performed by a transperitoneal method.
An incision four inches in length is made in the semilunar line, commencing about an inch
below the umbilicus and carried through tne abdominal wall into the peritoneal cavity. The
intestines are then pushed upward and held out of the way by a broad abdominal retractor, and
an incision is made through the peritoneum at the margin of the pelvis in the course of the artery,
and the vessel is secured in any part of its course which may seem desirable to the operator. The
advantages of this operation appear to be that if it is found necessary, the common iliac artery
can be ligated instead of the external iliac without extension or modification of the incision;
and secondly, that the vessel can be ligated without in any way interfering with the coverings
of the sac of an aneurism. Possibly a disadvantage may exist in the greater risk of hernia after
this method.
THE EXTERNAL ILIAC ARTERY 697
Collateral Circulation. — The principal anastomoses in carrying on the collateral circulation,
after the application of a ligature to the external iliac, are — the ilio-lumbar with the circumflex
iliac; the gluteal with the external circumflex; the obturator with the internal circumflex; the
sciatic with the superior perforating and circumflex branches of the profunda artery; and the
internal pudic with the external pudic. When the obturator arises from the epigastric it is
supplied with blood by branches, either from the internal iliac, the lateral sacral, or the internal
pudic. The epigastric receives its supply from the internal mammary and inferior intercostal
arteries, and from the internal iliac by the anastomoses of its branches with the obturator.
In the dissection of a limb eighteen years after the successful ligature of the external iliac
artery by Sir A. Cooper, the report of which is to be found in Guy's Hospital Reports, vol.
i. p. 50, the anastomosing branches are described in three sets: An anterior set. — 1, a very
large branch from the ilio-lumbar artery to the circumflex iliac; 2, another branch from the
ilio-lumbar, joined by one from the obturator, and breaking up into numerous tortuous branches
to anastomose with the external circumflex; 3, two other branches from the obturator, which
passed over the brim of the pelvis, communicated with the epigastric, and then broke up into a
plexus to anastomose with the internal circumflex. An internal set. — Branches given off from
the obturator, after quitting the pelvis, which ramified among the adductor muscles on the
inner side of the hip-joint, and joined most freely with branches of the internal circumflex.
A posterior set. — 1, three large branches from the gluteal to the external circumflex; 2, several
branches from the sciatic around the great sciatic notch to the internal and external circumflex,
and the perforating branches of the profunda.
Branches. — Besides several small branches to the Psoas muscle and the neigh-
boring lymphatic glands, the external iliac gives off two branches of considerable
size — the deep epigastric and deep circumflex iliac arteries.
The Internal or Deep Epigastric Artery (a. cpigastrica inferior) (Fig. 427)
arises from the external iliac a few lines above Poupart's ligament. It at first
descends to reach this ligament, and then ascends obliquely along the inner margin
of the internal abdominal ring, lying between the transversalis fascia and peri-
toneum, and, continuing its course upward, it pierces the transversalis fascia, and
passing over the semilunar fold of Douglas, enters the sheath of the Rectus muscle.
It then ascends on the posterior surface of the muscle, and finally divides into
numerous branches which anastomose, above the umbilicus, with the superior
epigastric branch of the internal mammary and with the inferior intercostal arteries
(Fig. 413). The deep epigastric artery bears a very important relation to the
internal abdominal ring as it passes obliquely upward and inward from its origin
from the external iliac. In this part of its course it lies along the lower and inner
margin of the ring and beneath the commencement of the spermatic cord. As
it passes to the inner side of the internal abdominal ring it is crossed by the vas
deferens in the male and the round ligament in the female.
Branches. — The branches of this vessel are the following: The cremasteric
(a. spermatica externa in the male, a. ligamenti teretis uteri in the jemale), which
accompanies the spermatic cord, and supplies the Cremaster muscle and other
coverings of the cord, anastomosing with the spermatic artery in the male,
and which accompanies the round ligament in the female; a pubic branch
(ramus pubicus), which runs along Poupart's ligament, and then descends behind
the os pubis to the inner side of the femoral ring, and anastomoses with offsets
from the obturator artery; muscular branches, some of which are distributed to the
abdominal muscles and peritoneum, anastomosing* with the lumbar and circum-
flex iliac arteries ; cutaneous branches perforate the tendon of the External oblique,
and supply the integument, anastomosing with branches of the superficial epi-
gastric.
Peculiarities. — The origin of the deep epigastric may take place from any part of the
external iliac between Poupart's ligament and two inches and a half above it, or it may arise
below this ligament, from the common femoral or from the deep femoral.
Union with Branches. — It frequently arises from the external iliac by a common trunk
with the obturator. Sometimes the epigastric arises from the obturator, the latter vessel being
furnished by the internal iliac, or the epigastric . may be formed by two branches, one derived
3m the external iliac, the other from the internal iliac.
698 THE BLOOD-VASCULAR SYSTEM
Surgical Anatomy. — The deep epigastric artery follows a line drawn from the middle of
Poupart's ligament toward the umbilicus; but shortly after this line crosses the linea semilunaris
the direction changes, and the course of the vessel is directly upward in the line of junction of
the inner third with the outer two-thirds of the Rectus muscle. It has important surgical rela-
tions, in addition to the fact that it is one of the principal means, through its anastomosis with
the internal mammary, in establishing the collateral circulation after ligature of either the com-
mon or external iliac arteries. It lies close to the internal abdominal ring, and is therefore
internal to an oblique inguinal hernia, but external to a direct inguinal hernia, as the hernia
emerges from the abdomen. It forms the outer boundary of Hesselbach's triangle. It is in
close relationship with the spermatic cord, which lies in front of it in the inguinal canal,
separated only by the transversalis fascia. The vas deferens hooks round its outer side.
The Deep Circumflex Iliac Artery (a. circwnflexa ilium profunda} (Fig. 427)
arises from the outer side of the external iliac nearly opposite the epigastric artery.
It ascends obliquely outward behind Poupart's ligament, contained in a fibrous
sheath formed by the junction of the transversalis and iliac fasciae, to the anterior
superior spinous process of the ilium. It then runs along the inner surface of the
crest of the ilium to about its middle, where it pierces the Transversalis, and
runs backward between that muscle and the Internal oblique, to anastomose with
the ilio-lumbar and gluteal arteries. Opposite the anterior superior spine of the
ilium it gives off a large branch which ascends between the Internal oblique and
Transversalis muscles, supplying them, and anastomosing with the lumbar and
epigastric arteries. It also gives off cutaneous branches.
ARTERIES OF THE LOWER EXTREMITY.
The artery which supplies the greater part of the lower extremity is the direct
continuation of the external iliac. It continues as a single trunk from Poupart's
ligament to the lower border of the Popliteus muscle, and here divides into two
branches, the anterior and posterior tibial, an arrangement exactly similar to what
occurs in the upper limb. For convenience of description, the upper part of the
main trunk is named femoral, the lower part, popliteal.
THE FEMORAL ARTERY (A. FEMORALIS) (Figs. 432 and 433).
The femoral artery commences immediately behind Poupart's ligament,
midway between the anterior superior spine of the ilium and the symphysis
pubis, and, passing down the forepart and inner side of the thigh, terminates
at the opening in the Adductor magnus, at the junction of the middle with the
lower third of the thigh, where it becomes the popliteal artery. The vessel, at
the upper part of the thigh, lies in front of the hip-joint, just on a line with the
innermost part of the head of the femur; in the lower part of its course it is in close
relation with the inner side of the shaft of the bone, and between these two parts
the vessel is some distance from the bone. In the upper third of the thigh it is
contained in a triangular space called Scarpa's triangle. In the middle third of the
thigh it is contained in an aponeurotic canal called Hunter's canal.
Scarpa's Triangle (trigonum femorale}.— Scarpa's triangle corresponds to the
depression seen immediately below the fold of the groin. It is a triangular space,
the apex of which is directed downward, and the sides formed externally by the
Sartorius, internally by the inner margin of the Adductor longus, and above by
Poupart's ligament. The floor of the space is formed from without inward by the
Iliacus, Psoas, Pectineus (in some cases a small part of the Adductor brevis), and
the Adductor longus muscles; and it is divided into two nearly equal parts by the
femoral vessels, which extend from the middle of its base to its apex, the artery
THE FEMORAL ARTERY
699
giving off in this situation its superficial and profunda branches, the vein receiving
the deep femoral and internal saphenous. On the outer side of the femoral artery
is the femoral nerve dividing into its branches. In the outer corner of the space
is the external cutaneous nerve. Within the sheath of the artery, and lying upon
the outer side of the vessel, is the crural branch of the genito-femoral nerve. At
the base of the triangle the vein is to the inner side of the artery; at the apex
of the triangle it is passing behind the artery. Besides the vessels and nerves,
this space contains some fat and lymphatics.
SUPERFICIAL
EPIGASTRIC
SUPERFICIAL CIR.
CUMFLEX ILIAC
COMMON
FEMORAL
EXTERNAL
CIRCUMFLEX
DESCENDING
RAMUS OF
EXTERNAL
CIRCUMFLEX
SUPERIOR EXTER-
NAL ARTICULAR
BRANCH OF
POPLITEAL
SUPERFICIAL
EXTERNAL
PUDIC
DEEP
EXTERNAL
PUDIC
ANASTOMOTICA
MAGNA
SUPERIOR INTERNAL
ARTICULAR
BRANCH OF
POPLITEAL
FIG. 432. — Scheme of the femoral artery. (Poirier and Charpy.)
Hunter's Canal or the Adductor Canal (canalis adductorius [Hunteri]).—
This is the aponeurotic space in the middle third of the thigh, extending from
the apex of Scarpa's triangle to the femoral opening in the Adductor magnus
muscle. It is bounded, externally, by the Vastus internus; internally by the
Adductors tongus and magnus muscles; and is covered in by a strong apon-
eurosis which extends transversely from the Vastus internus across the femoral
700
THE BLOOD- VASCULAR SYSTEM
'rotum.
vessels to the Adductor longus and magnus; lying on which aponeurosis is the
Sartorius muscle. It contains the femoral artery and vein enclosed in their own
sheath of areolar tissue, the vein being behind and on the outer side of the artery,
and the internal or long saphenous
nerve lying at first on the outer side
and then in front of the vessels.
For convenience of description,
and also in reference to its surgi-
cal anatomy, the femoral artery is
divided into a short trunk, about
an inch and a half or two inches
long, which is known as the com-
mon femoral artery, while the re-
mainder of the vessel is termed
the superficial femoral artery, to
distinguish it from the deep femoral
(profunda femoris), a large branch
given off from the common femoral
at its termination, and which,
by its derivation, from the parent
trunk, marks the commencement
of the superficial femoral artery.
The Common Femoral Artery
(Figs. 432 and 433).
The common femoral artery is
very superficial, being covered by
the skin and superficial fascia,
superficial inguinal lymphatic
glands, the iliac portion of the
fascia lata, and the prolongation
downward of the transversalis
fascia, which forms the anterior
part of the sheath of the vessels.
It has in front of it filaments from
the crural branch of the geni to-
femoral nerve, the superficial cir-
cumflex iliac vein, and occasionally
the superficial epigastric vein. It
rests on the inner margin of the
Psoas muscle, which separates it
from the capsular ligament of the
hip-joint, and a little lower on the
Pectineus muscle ; and crossing
behind it is the branch to the
Pectineus from the femoral nerve.
Separating the artery from the
Pectineus muscles is the pubic portion of the fascia lata and the prolongation
from the fascia covering the Iliacus muscle, which forms the posterior layer of the
sheath of the vessels. The femoral nerve lies about half an inch to the outer
side of the common femoral artery, being separated from the artery by a small
part of the Psoas muscle. To the inner side of the artery is the femoral vein,
between the margins of the Pectineus and Psoas muscles. The- two vessels are
Long saphenous
nerve.
Superior external
articular.
Inferior internal
articular.
Anastomotica
magna.
Superior internal
articular.
Inferior internal
articular.
Anterior tibial
recurrent.
FIQ. 433. — The femoral artery.
THE SUPERFICIAL FEMORAL ARTERY
701
enclosed in a strong fibrous sheath formed by the proper sheath of the vessels,
strengthened by fascia (see page 511) ; the artery and vein are separated, however,
from one another by a thin fibrous partition.
PLAN OF THE RELATIONS OF THE COMMON FEMORAL ARTERY.
In front.
Skin and superficial fascia.
Superficial inguinal glands.
Iliac portion of fascia lata.
Prolongation of transversalis fascia.
Crural branch of genito-femoral nerve.
Superficial circumflex iliac vein.
Superficial epigastric vein.
Inner side.
Femoral vein.
Outer side.
Small part of Psoas muscle,
separating the artery from the
femoral nerve.
Behind.
Prolongation of fascia covering the Iliacus muscle.
Pubic portion of fascia lata.
Nerve to Pectineus.
Psoas muscle.
Pectineus muscle.
Capsule of hip-joint.
The Superficial Femoral Artery (Figs. 432 and 433).
The superficial femoral artery is only superficial where it lies in Scarpa's
triangle. Here it is covered by the skin, superficial and deep fascia, and
crossed by the internal cutaneous branch of the femoral nerve. In Hunter's canal
it is more deeply seated, being covered by the integument, the superficial and
deep fascia, the Sartorius and the aponeurotic covering of Hunter's canal. The
internal saphenous nerve crosses the artery from without inward. Behind, the
artery lies at its upper part on the femoral vein and the profunda artery and
vein, which separate it from the Pectineus muscle, and lower down on the Adduc-
tor longus and Adductor magnus muscles. To the outer side is the long saphenous
nerve and the nerve to the Vastus internus, the Vastus internus muscle, and,
at its lower part, the femoral vein. To the inner side is the Adductor longus
above and the Adductor magnus and Sartorius below.
PLAN OF THE RELATIONS OF THE SUPERFICIAL FEMORAL ARTERY.
In front.
Skin, superficial and deep fasciae.
Internal cutaneous nerve.
Sartorius.
Aponeurotic covering of Hunter's canal.
Internal saphenous nerve.
Outer side.
Long saphenous nerve.
Nerve to vastus internus.
Vastus internus.
Femoral vein (below).
Behind.
Femoral vein.
Profunda artery and vein.
Pectineus muscle.
Adductor longus.
Adductor magnus.
Inner side.
Adductor longus.
Adductor magnus.
Sartorius.
702 THE BLOOD-VASCULAR SYSTEM
The femoral vein, at Poupart's ligament, lies close to the inner side of the artery,
separated from it by a thin fibrous partition; but lower down it is behind it, and
then to its outer side.
The internal saphenous nerve is situated on the outer side of the artery, in the
middle third of the thigh, beneath the aponeurotic covering of Hunter's canal, but
not usually within the sheath of the vessels. The internal cutaneous nerve passes
obliquely across the upper part of the sheath of the femoral artery.
Peculiarities. Double Femoral Reunited.— Several cases are recorded in which the femoral
artery divided into two trunks below the origin of the profunda, and became reunited near the
opening of the Adductor magnus so as to form a single popliteal artery. One of them occurred
in a patient operated upon for popliteal aneurism.
Change of Position. — A few cases have been recorded in which the femoral artery was
situated at the back of the thigh, the vessel being continuous above with the internal iliac, escap-
ing from the pelvis through the great sacro-sciatic foramen, and accompanying the great sciatic
nerve to the popliteal space, where its division occurred in the usual manner. The external
iliac in these cases was small, and terminated in the profunda.
Position of the Vein. — The femoral vein is occasionally placed along the inner side of the
artery, throughout the entire extent of Scarpa's triangle, or it may be slit so that a large vein is
placed on each side of the artery for a greater or less extent.
Origin of the Profunda. — This vessel occasionally arises from the inner side, and, more
rarely, from the back of the common trunk; but the more important peculiarity, in a surgical
point of view, is that which relates to the height at which the vessel arises from the femoral. In
three-fourths of a large number of cases it arose between one or two inches below Poupart's
ligament; in a few cases the distance was less than an inch; more rarely, opposite the ligament;
and in one case, above Poupart's ligament, from the external iliac. Occasionally, the distance
between the origin of the vessel and Poupart's ligament exceeds two inches, and in one case it
was found to be as much as four inches.
Surface Marking. — The upper two-thirds of a line drawn from a point midway between
the anterior superior spine of the ilium and the symphysis pubis to the adductor tubercle on
the inner condyle of the femur, with the thigh abducted and rotated outward, will indicate the
course of the femoral artery.
Surgical Anatomy. — Compression of the femoral artery, which is constantly requisite in
amputations and other operations on the lower limbs, and also for the cure of popliteal aneurisms,
is most effectually made immediately below Poupart's ligament. In this situation the artery is
very superficial, and is merely separated from the ascending ramus of the os pubis by the Psoas
muscle; so that the surgeon, by means of his thumb or a compressor, may effectually control the
circulation through it. This vessel may also be compressed in the middle third of the thigh by
placing a compress over the artery, beneath the tourniquet, and directing the pressure from
within outward, so as to compress the vessel against the inner side of the shaft of the femur.
The application of a ligature to the femoral artery may be required in the cases of wound
or aneurism of the arteries of the leg, of the popliteal or femoral;1 and the vessel may be exposed
and tied in any part of its course. The great depth of this vessel at its lower part, its close con-
nection with important structures, and the density of its sheath render the operation in this
situation one of much greater difficulty than the application of a ligature at its upper part,
where it is more superficial.
Ligature of the common femoral artery is usually considered unsafe, on account of the con-
nection of large branches with it — viz., the deep epigastric and the deep circumflex iliac arising
just above Poupart's ligament; on account of the number of small branches which arise from
it in its short course; and on account of the uncertainty of the origin of the profunda femoris,
which, if it arise high up, would be too close to the ligature for the formation of a firm coagu-
lum. The profunda sometimes arises higher than the point above mentioned, and rarely between
two or three inches (in one case four) below Poupart's ligament. It would appear, then, that
the most favorable situation for the application of a ligature to the femoral is on the superficial
femoral at the apex of Scarpa's triangle. In order to expose the artery in this situation, an inci-
sion between three and four inches long should be made in the course of the vessel, the patient
lying in the recumbent position, with the limb slightly flexed and abducted, and rotated outward.
A large vein is frequently met with, passing in the course of the artery to join the internal saphe-
nous vein; this must be avoided, and the fascia lata having been cautiously divided and the
Sartorius exposed, that muscle must be drawn outward in order to expose fully the sheath of
the vessels. The finger being introduced into the wound and the pulsation of the artery felt,
the sheath should be opened on the outer side of the vessel to a sufficient extent to allow of the
1 Ligation of the femoral artery has been also recommended and performed for elephantiasis of the leg and
acute inflammation of the knee-joint (Maunder, Clin. Soc. Trans., vol. ii. p. 37). — ED. of 15th English edition.
THE SUPERFICIAL FEMORAL ARTERY 703
introduction of the ligature, but no farther; otherwise the nutrition of the coats of the vessel
may be interfered with, or muscular branches which arise from the vessel at irregular intervals
may be divided. In this part of the operation the long saphenous nerve and the nerve to the
Vastus internus, which is in close relation with the sheath, should be avoided. The aneurism
needle must be carefully introduced and kept close to the artery, to avoid the femoral vein, which
lies behind the vessel in this part of its course.
To expose the artery in Hunter's canal, an incision should be made between three and four
inches in length, a finger's breadth internal to the line of the artery, in the middle of the thigh
— i, e., midway between the groin and the knee. The integument is first divided. The fascia
lata having been divided, and the outer border of the Sartorius muscle exposed, it should be
drawn inward, when the strong fascia which is stretched across from the Adductors to the Vastus
internus will be exposed, and must be freely divided; the sheath of the vessels is now seen,
and must be opened, and the artery secured by passing the aneurism needle between the vein
and artery in the direction from without inward. The femoral vein in this situation lies on the
outer side of the artery and the long saphenous nerve on the anterior and outer side of the
artery.
It has been seen that the femoral artery occasionally divides into two trunks below the origin
of the profunda. If in the operation for tying the femoral two vessels are met with, the surgeon
should alternately compress each, in order to ascertain which vessel is connected with the
aneurismal tumor or with the bleeding from the wound, and that one only should be tied which
controls the pulsation or hemorrhage. If, however, it is necessary to compress both vessels
before the circulation in the tumor is controlled, both should be tied, as it would be probable that
they became reunited, as in the instances referred to above.
In wounds of the femoral artery the question of the mode of treatment is of considerable
importance. If the wound in the superficial structures is a large one, the injured vessel must
be exposed and tied; but if the wound is a punctured one and the bleeding has ceased, the ques-
tion will arise whether to cut down upon the artery or to trust to pressure. Mr. Cripps1 advises
that if the wound is in the "upper part of the thigh — that is to say, in a position where the
femoral artery is comparatively superficial — the surgeon may enlarge the opening with a good
prospect of finding the wounded vessel without an extensive or prolonged operation. If the
wound be in the lower half of the thigh, owing to the greater depth of the artery and the possi-
bility of its being the popliteal that is wounded, the search is rendered a far more severe and
hazardous operation, and it should not be undertaken until a thorough trial of pressure has
proved ineffectual."
Great care and attention are necessary for the successful application of pressure. The limb
should be carefully bandaged from the foot upward to the wound, which is not covered, and then
onward to the groin. The wound is then dusted with iodoform or boracic powder and a conical
pad applied over the wound. Rollers the thickness of the index finger are then placed along
the course of the vessel above and below the wound, and the whole carefully bandaged to a back
splint with a foot-piece.
Collateral Circulation. — When the common femoral is tied the main channels for carrying
on the circulation are the anastomoses of the gluteal and circumflex iliac arteries above with the
external circumflex below; of the obturator and sciatic above with the internal circumflex below;
and of the comes nervi ischiadici with the arteries in the ham.
The principal agents in carrying on the collateral circulation after ligature of the superficial
femoral artery are, according to Sir A. Cooper, as follows:
"The arteria profunda formed the new channel for the blood. The first artery sent off
passed down close to the back of the thigh-bone, and entered the two superior articular branches
of the popliteal artery.
"The second new large vessel, arising from the profunda at the same part with the former,
passed down by the inner side of the Biceps muscle to a branch of the popliteal which was dis-
tributed to the Gastrocnemius muscle; whilst a third artery, dividing into several branches,
passed down with the sciatic nerve behind the knee-joint, and some of its branches united them-
selves with the inferior articular arteries of the popliteal, with some recurrent branches of those
arteries, with arteries passing to the Gastrocnemii, and, lastly, with the origin of the anterior
and posterior tibial arteries.
" It appears, then, that it is those branches of the profunda which accompany the sciatic
nerve that are the principal supporters of the new circulation."2
In Porta's work3 (tab. xii., xiii.) is a good representation of the collateral circulation after
the ligature of the femoral artery. The patient had survived the operation three years. The
lower part of the artery is at least as large as the upper; about two inches of the vessel appear
to have been obliterated. The external and internal circumflex arteries are seen anastomosing
by a great number of branches with the lower branches of the femoral (muscular and anasto-
1 Heath's Dictionary of Practical Surgery, vol. i. p. 525. 2 Med.-Chir. Trans., vol. ii., 1811.
3 Alterazioni patologiche delle Arterie.
704 THE BLOOD- VASCULAR SYSTEM
motica magna) and with the articular branches of the popliteal. The branches from the external
circumflex are extremely large and numerous. One very distinct anastomosis can be traced
between this artery on the outside and the anastomotica magna on the inside through the inter-
vention of the superior external articular artery, with which they both anastomose; and blood
reaches even the anterior tibial recurrent from the external circumflex by means of anastomosis
with the same external articular artery. The perforating branches of the profunda are also
seen bringing blood round the obliterated portion of the artery into long branches (muscular)
which have been ^iven off just below that portion. The termination of the profunda itself
anastomoses most freely with the superior external articular. A long branch of anastomosis
is also traced down from the internal iliac by means of the comes nervi ischiadici of the sciatic,
which anastomoses on the popliteal nerves with branches from the popliteal and posterior tibial
arteries. In this case the anastomosis had been too free, since the pulsation and growth of the
aneurism recurred, and the patient died after ligature of the external iliac.
There is an interesting preparation in the Museum of the Royal College of Surgeons of a
limb on which John Hunter had tied the femoral artery fifty years before the patient's death.
The whole of the superficial femoral and popliteal artery seems to have been obliterated. The
anastomosis by means of the comes nervi ischiadici, which is shown in Porta's plate, is distinctly
seen: the external circumflex and the termination of the profunda artery seem to have been the
chief channels of anastomoses; but the injection has not been a very successful one.
Branches (Figs. 432 and 433). — The branches of the femoral artery are — the
Superficial Epigastric. ( External Circumflex.
Superficial Circumflex Iliac. Profunda Femoris -\ Internal Circumflex.
Superficial External Pudic. ( Three Perforating.
Deep External Pudic. Muscular.
Anastomotica Magna.
The Superficial Epigastric (a. epigastrica superficialis) arises from the fem-
oral about half an inch below Poupart's ligament, and, passing through the
saphenous opening in the fascia lata, ascends on the abdomen, in the superficial
fascia covering the External oblique muscle, nearly as high as the umbilicus. It
distributes branches to the superficial inguinal glands, the superficial fascia, and
the integument, anastomosing with branches of the deep epigastric.
The Superficial Circumflex Iliac (a. circumflexa ilium superficialis) , the
smallest of the cutaneous branches, arises close to the preceding, and, piercing the
fascia lata, runs outward, parallel with Poupart's ligament, as far as the crest of
the ilium, dividing into branches which supply the integument of the groin, the
superficial fascia, and the superficial inguinal lymphatic glands, anastomosing
with the deep circumflex iliac and with the gluteal and external circumflex
arteries.
The Superficial External Pudic or the Superior Superficial External Pudic
(a. pudenda externa superficialis) arises from the inner side of the femoral artery,
close to the preceding vessels, and, after passing through the saphenous opening,
courses inward, across the spermatic cord or round ligament, to be distributed to
the integument on the lower part of the abdomen, the penis and scrotum in the
male, and the labium in the female, anastomosing with branches of the internal
pudic.
The Deep External Pudic or the Deep Superficial External Pudic (a. pudenda
externa profunda}, more deeply seated than the preceding, passes inward across
the Pectineus and Adductor longus muscles, covered by the fascia lata, which it
pierces at the inner border of the thigh, its branches being distributed, in the male,
to the integument of the scrotum and perinaeum; and in the female to the labium,
anastomosing with branches of the superficial perineal artery.
The Deep Femoral or the Profunda Femoris (a. profunda femoris) (Figs. 432
and 433) nearly equals the size of the superficial femoral. It arises from the
outer and back part of the femoral artery, from one to two inches below Poupart's
THE SUPERFICIAL FEMORAL ARTERY 705
ligament. It at first lies on the outer side of the superficial femoral, arid then
passes behind it and the femoral vein to the inner side of the femur, and, passing
downward beneath the Adductor longus, terminates at the lower third of the thigh
in a small branch which pierces the Adductor magnus (and from this circum-
stance is sometimes called the fourth perforating artery), and is distributed to the
flexor muscles on the back of the thigh, anastomosing with branches of the
popliteal and inferior perforating arteries.
Relations. — Behind, it lies first upon the Iliacus, and then on the Pectineus,
Adductor brevis, and Adductor magnus muscles. In front, it is separated from
the superficial femoral artery, above by the femoral and profunda veins, and
below by the Adductor longus. On its outer side the origin of the Vastus interims
separates it from the femur.
PLAN OF THE RELATIONS OF THE PROFUNDA ARTERY.
In front.
Superficial femoral artery.
Femoral and profunda veins.
Adductor longus.
Outer side.
Vastus internus.
Behind.
Iliacus.
Pectineus.
Adductor brevis.
Adductor magnus.
Branches. — The profunda gives off the following named branches:
Muscular. Internal circumflex.
External circumflex. Four perforating.
Muscular Branches are given off in Scarpa's triangle, and also from the vessel as
it lies between the Adductor muscles.
The External Circumflex Artery (a. circumflexa femoris lateralis) supplies the
muscles on the front of the thigh. It arises from the outer side of the profunda,
passes horizontally outward, between the divisions of the femoral nerve and
behind the Sartorius and Rectus muscles, and divides into three sets of branches —
ascending, transverse, and descending.
The ascending branch (ramus asceiidens) passes upward, beneath the Tensor
fascine femoris muscle, to the outer side of the hip, anastomosing with the terminal
branches of the gluteal arid deep circumflex iliac arteries. It sends out muscular
branches. The descending branch (ramus descendens) passes downward, behind
the Rectus, upon the Vasti muscles, to which its branches are distributed, one
or two passing beneath the Vastus externus as far as the knee, anastomosing with
the superior articular branches of the popliteal artery. These are accompanied by
the branch of the femoral nerve to the Vastus externus. The transverse branch,
the smallest, passes outward over the Crureus, pierces the Vastus externus, and
winds round the ferpur to its back part, just below the great trochanter, anasto-
mosing at the back of the thigh with the internal circumflex, sciatic, and superior
perforating arteries.
The Internal Circumflex Artery (a. circumflexa femoris medialis], smaller than
the external, arises from the inner and back part of the profunda, and winds
round the inner side of the femur, between the Pectineus and Psoas muscles. On
45
706 THE BLOOD-VASCULAR SYSTEM
reaching the upper border of the Adductor brevis it gives off two muscular branches,
one of which passes inward to be distributed to the Adductor muscles, the Gracilis,
and Obturator externus, anastomosing with the obturator artery; the other
descends, and passes beneath the Adductor brevis, to supply it and the great
Adductor; while the continuation of the vessel passes backward and divides into
an ascending and a transverse branch (Fig. 348). The ascending branch (ramus
profundus) passes obliquely upward upon the tendon of the Obturator externus
and under cover of the Quadratus femoris toward the digital fossa, where it
anastomoses with twigs from the gluteal and sciatic arteries. The transverse
branch (ramus superficialis) , larger than the ascending, appears between the
Quadratus femoris and upper border of the Adductor magnus, anastomosing with
the sciatic, external circumflex, and superior perforating arteries, the crucial anas-
tomosis. Opposite the hip-joint the artery gives off an articular vessel (ramus
acetabuli), which enters the joint beneath the transverse ligament; and, after sup-
plying the adipose tissue, passes along the round ligament to the head of the bone.
The Perforating Arteries (Figs. 431, 432, and 433), usually three in number, are
so called from their perforating the tendon of the Adductor magnus muscle to
reach the back of the thigh. They pass backward close to the linea aspera of the
femur, under cover of small tendinous arches in the Adductor magnus. The
first is given off above the Adductor brevis, the second in front of that muscle,
and the third immediately below it.
The first perforating artery (a. perforans primd) passes backward between the
Pectineus and Adductor brevis (sometimes perforates the latter) ; it then pierces
the Adductor magnus close to the linea aspera. It gives off branches which supply
the Adductor brevis, the Adductor magnus, the Biceps, and Gluteus maximus
muscles, and anastomoses with the sciatic, internal and external circumflex, and
middle perforating arteries. The second perforating artery (a. perforans secunda],
larger than the first, pierces the tendons of the Adductor brevis and Adductor
magnus muscles, and divides into ascending and descending branches, which
supply the flexor muscles of the thigh, anastomosing with the first and third
perforating arteries. The second artery frequently arises in common with the first.
The nutrient artery of the femur is usually given off from this branch. The third
perforating artery (a. perforans tertia) is given off below the Adductor brevis; it
pierces the Adductor magnus, and divides into branches which supply the flexor
muscles of the thigh ; anastomosing above with the higher perforating arteries, and
below with the terminal branches of the profunda and the muscular branches of
the popliteal. A fourth perforating artery is represented by the termination of the
profunda femoris artery.
The nutritive artery of the femur (a. nutricia femoris), if single, comes from the
second perforating artery; if double, from the first and third perforating arteries.
If double, one vessel is called superior and the other inferior.
Muscular Branches (rami musculares) are given off from the superficial femoral
throughout its entire course. They vary from two to seven in number, and supply
chiefly the Sartorius and Vastus internus.
The Anastomotica Magna (a. genii supremo) (Figs. 432 and 433) arises from
the femoral artery just before it passes through the tendinous opening in the
Adductor magnus muscle, and immediately divides into a superficial and deep branch.
The Superficial Branch (ramus saphenous) pierces the aponeurotic covering of
Hunter's canal, and accompanies the long saphenous nerve to the inner side of the
thigh. It passes between the Sartorius and Gracilis muscles, aid, piercing the fascia
lata, is distributed to the integument of the upper and inner part of the leg, anasto-
mosing with the inferior internal articular artery.
The Deep Branch (ramus musculoarticularis) descends in the substance of the
Vastus internus, lying in front of the tendon of the Adductor magnus, to the inner
side of the knee, where it anastomoses with the superior internal articular artery
THE POPLITEAL SPACE
707
-Sural arteries.
and the anterior recurrent branch of the
anterior tibial. A branch from this vessel
crosses outward above the articular surface
of the femur, forming an anastomotic arch
with the superior external articular artery,
and supplies branches to the knee-joint.
THE POPLITEAL ARTERY (A. POPLITEA)
(Figs. 431 and 432).
The popliteal artery commences at the ter-
mination of the femoral at the opening in the
Adductor magnus, and, passing obliquely
downward and outward behind the knee-joint
to the lower border of the Popliteus muscle
divides into the anterior and posterior tibial
arteries. A portion of the artery lies in the
popliteal space; but above and below, to
a considerable extent, it is covered by the
muscles which form the boundaries of the
space, and is therefore beyond the confines
of the hollow.
The Popliteal Space (Fig. 434).
Dissection.— A vertical incision about eight inches
in length should be made along the back part of the
knee-joint, connected above and below by a trans-
verse incision from the inner to the outer side of the
limb. The flaps of integument included between
these incisions should be reflected in the direction
shown in Fig. 345, page 525.
Boundaries. — The popliteal space, or the
ham, is a lozenge-shaped space, widest at the
back part of the knee-joint, and deepest above
the articular end of the femur. It is bounded
externally, above the joint, by the Biceps, and
below the joint by the Plantaris and external
head of the Gastrocnemius. Internally, above
the joint, by the Semimembranosus, Semiten-
dinosus, Gracilis, and Sartorius; below the
joint, by the inner head of the Gastrocnemius.
Above, it is limited by the apposition of the
inner and outer hamstring muscles ; below, by
the junction of the two heads of the Gastroc-
nemius. The floor is formed by the lower
part of the posterior surface of the shaft
of the femur, the posterior ligament of the
knee-joint, the upper end of the tibia, and
the fascia covering the Popliteus muscle, and
the space is covered in by the fascia lata.
Contents. — It contains the popliteal vessels
and their branches, together with the termination of the external saphenous vein,
the internal and external popliteal nerves and some of their branches, the lower
extremity of the small sciatic nerve, the articular bra*nch from the obturator nerve,
a few small lymphatic glands, and a considerable quantity of loose adipose tissue.
-Anterior peroneal.
FIG. 434. — The popliteal, posterior tibial, and
peroneal arteries.
708 THE BLOOD-VASCULAR SYSTEM
Position of Contained Parts. — The internal popliteal nerve descends in the
middle line of the space lying superficial and crossing the artery from without
inward. The external popliteal nerve descends on the outer side of the upper part
of the space, lying close to the tendon of the Biceps muscle. More deeply at the
bottom of the space are the popliteal vessels, the vein lying superficial to the artery,
to which it is closely united by dense areolar tissue; it is a thick-walled vessel, and
lies at first to the outer side of the artery, and then crosses it to gain the inner side
below; sometimes the vein is double, the artery lying between the two venae comites,
which are usually connected by short transverse branches. More deeply and, at
its upper part, close to the surface of the bone is the popliteal artery, and passing
off from it at right angles are its articular branches. The articular branch from
the obturator nerve descends upon the popliteal artery to supply the knee, and
occasionally there is found deep in the space an articular filament from the great
sciatic nerve.
The popliteal lymphatic glands, four or five in number, are found surrounding
the artery; one usually lies superficial to the vessel; another is situated between
it and the bone, and the rest are placed on either side of it.
The Popliteal Artery, in its course downward from the aperture in the Adductor
magnus to the lower border of the Popliteus muscle, rests first on the inner surface
of the femur, and is then separated by a little fat from the hollowed popliteal
surface of the bone; in the middle of its course it rests on the posterior ligament
of the knee-joint, and below on the fascia covering the Popliteus muscle. Super-
ficially, it is covered above by the Semimembranosus ; in the middle of its course,
by a quantity of fat, which separates it from the deep fascia and integument; and
below it is overlapped by the Gastrocnemius, Plantaris, and Soleus muscles, the
popliteal vein, and the internal popliteal nerve. The popliteal vein, which is
intimately attached to the artery, lies superficial and external to it above; it then
crosses it and lies to its inner side. The internal popliteal nerve is still more
superficial and external above, but below the joint it crosses the artery and lies
on its inner side. Laterally, the artery is bounded by the muscles which are
situated on either side of the popliteal space.
PLAN OF THE RELATIONS or THE POPLITEAL ARTERY.
In front.
Femur.
Ligamentum posticum.
Popliteus.
Inner side /** ~"~\ Outer side.
Semimembranosus. / \
Internal oondvle I p°Pliteal 1 Outer condyle.
, ,, I Artery- } Gastrocnemius (outer head).
Gastrocnemius (inner head). \ / p. .
Behind.
Semimembranosus.
Fascia.
Popliteal vein.
Internal popliteal nerve.
Gastrocnemius.
Plantaris.
Soleus.
Peculiarities in Point of Division.— Occasionally the popliteal artery divides prematurely
into its terminal branches; this unusual division occurs most frequently opposite the knee-joint-
The anterior tibial under these circumstances may pass in front of the Popliteus muscle.
Unusual Branches.— The artery sometimes divides into the anterior tibial and peroneal, the
posterior tibial being wanting or very small. Occasionally the popliteal is found to divide into
three branches, the anterior and posterior tibial and peroneal.
THE POPLITEAL SPACE 709
Surface Marking. — The course of the upper part of the popliteal artery is indicated by
a line drawn from the outer border of the Semimembranosus muscle at the junction of the
middle and lower' third of the thigh obliquely downward to the middle of the popliteal space,
exactly behind the knee-joint. From this point it passes vertically downward to the level of a
line drawn through the lower part of the tubercle of the tibia.
Surgical Anatomy. — The popliteal artery is not infrequently the seat of injury. It may be
torn by direct violence, as by the passage of a cart-wheel over the knee or by hyper-extension of
the knee; and in the dead body, at all events, the middle and internal coats may be ruptured by
extreme flexion. It may also be lacerated by fracture of the lower part of the shaft of the
femur or by antero-posterior dislocation of the knee-joint. It has been torn in breaking down
adhesions in cases of fibrous ankylosis of the knee, and is in danger of being wounded, and in
fact has been wounded, in performing Macewen's operation of osteotomy of the lower end of the
femur for genu valgum. In addition, Spencer records a case in which the popliteal artery was
wounded from in front by a stab just below the knee, the knife passing through the interosseous
space. The popliteal artery is more frequently the seat of aneurism than is any other artery
in the body, with the exception of the thoracic aorta/ This is due no doubt, in a great measure,
to the amount of movement to which it is subjected, and to the fact that it is supported by loose
and lax tissue only, and not by muscles, as is the case with most arteries.
Ligature of the popliteal artery is required in cases of wound of that vessel, but for aneurism
of the posterior tibial it is preferable to tie the superficial femoral. The popliteal may be tied
in the upper or lower part of its course; but in the middle of the ham the operation is attended
with considerable difficulty, from the great depth of the artery and from, the extreme degree of
tension of the lateral boundaries of the space.
In order to expose the vessel in the upper part of its course, the patient should be placed
in the supine position, with the knee flexed and the thigh rotated outward, so that it rests on
its outer surface; an incision three inches in length, beginning at the junction of the middle
and lower third of the thigh, is to be made parallel to and immediately behind the tendon of
the Adductor magnus, and the skin, superficial and deep fascia divided. The tendon of the
muscle is thus exposed, and is to be drawn forward and the hamstring tendons backward. A
quantity of fatty tissue will now be opened up, in which the artery will be felt pulsating. This
is to be separated with the point of a director until the artery is exposed. The vein and nerve
will not be seen, as they lie to the outer side of the artery. The sheath is to be opened and
the aneurism needle passed from before backward, keeping its point close to the artery for fear
of injuring the vein. The only structure to avoid is the long saphenous vein in the superficial
incision. The upper part of the popliteal artery may also be tied by an incision on the back of
the limb, along the outer margin of the Semimembranosus, but the operation is a more difficult
one, as the internal popliteal nerve and the popliteal vein are first exposed, and great care has
to be exercised in separating them from the artery.
To expose the vessel in the lower part of its course, where the artery lies between the two
heads of the Gastrocnemius, the patient should be placed in the prone position with the limb
extended. An incision should then be made through the integument in the middle line, com-
mencing opposite the bend of the knee-joint, care being taken to avoid the external saphenous
vein and nerve. After dividing the deep fascia and separating some dense cellular membrane,
the artery, vein, and nerve will be exposed, descending between the two heads of the Gastrocne-
mius. Some muscular branches of the popliteal should be avoided if possible, or, if divided,
tied immediately. The leg being now flexed, in order the more effectually to separate the two
heads of the Gastrocnemius, the nerve should be drawn inward and the vein outward, and the
aneurism needle passed between the artery and vein from without inward.
Branches. — The branches of the popliteal artery are — the
Muscular { Superior. Superior External Articular.
\ Inferior or Sural. Azygos Articular.
Cutaneous. , Inferior Internal Articular.
Superior Internal Articular. Inferior External Articular.
The Superior Muscular Branches, two or three in number, arise from the
upper part of the popliteal artery, and are distributed to the lower part of the
Adductor magnus and flexor muscles of the thigh, anastomosing with the fourth
perforating branch of the profunda.
The Inferior Muscular (aa. surales) are two large branches which are dis-
tributed to the two heads of the Gastrocnemius and to the Plantaris muscle. They
arise from the popliteal artery opposite the knee-joint.
710 THE BLOOD-VASCULAR SYSTEM
The Cutaneous Branches arise separately from the popliteal artery or from
some of its branches ; they descend between the two heads of the. Gastrocnemius
muscle, and, piercing the deep fascia, are distributed to the integument of the
calf. One branch usually accompanies the short, or external, saphenous vein,
the superficial sural artery.
The Superior Articular Arteries, two in number, arise one on each side of the
popliteal, and wind round the femur immediately above its condyles to the front
of the knee-joint. The internal branch (a. genu superior medialis] winds inward
beneath the hamstring muscles, to which it supplies branches, above the inner
head of the Gastrocnemius, and, passing beneath the tendon of the Adductor
magnus, divides into two branches, one of which supplies the Vastus internus,
inosculating with the anastomotica magna and inferior internal articular; the other
ramifies close to the surface of the femur, supplying it and the knee-joint, and an-
astomosing with the superior external articular artery. This branch is frequently
of small size, a condition which is associated with an increase in the size of the an-
astomotica magna. The external branch (a. genu superior lateralis) passes above
the outer condyle, beneath the tendon of the Biceps, and divides into a superficial
and deep branch: the superficial branch supplies the Vastus externus, and anasto-
moses with the descending branch of the external circumflex and the inferior exter-
nal articular arteries; the deep branch supplies the lower part of the femur and
knee-joint, and forms an anastomotic arch across the bone with the anastomotica
magna and the inferior internal articular arteries.
The Azygos Articular (a. genu media) is a small branch arising from the pop-
liteal artery opposite the bend of the knee-joint. It pierces the posterior ligament,
and supplies the ligaments and synovial membrane in the interior of the articu-
lation.
The Inferior Articular Arteries, two in number, arise from the popliteal
beneath the Gastrocnemius, and wind round the head of the tibia below the joint.
The internal branch (a. genu inferior medialis) first descends along the upper mar-
gin of the Popliteus muscle, to which it gives branches; it then passes below the
inner tuberosity, beneath the internal lateral ligament, at the anterior border of
which it ascends to the front and inner side of the joint, to supply the head of the
tibia and the articulation of the knee, anastomosing with the inferior external
articular and superior internal articular arteries. The external branch (a. genu
inferior lateralis] passes outward above the head of the fibula, to the front of the
knee-joint, passing in its course beneath the outer head of the Gastrocnemius, the
external lateral ligament, and the tendon of the Biceps muscle, and divides into
branches which anastomose with the inferior internal articular artery, the superior
external articular artery, and the anterior recurrent branch of the anterior tibial.
Gircumpatellar Anastomosis. — Around and above the patella, and on the con-
tiguous ends of the femur and tibia, is a large network of vessels, forming a super-
ficial and a deep plexus. The superficial plexus is situated between the fascia and
skin round about the patella; the deep plexus, which forms a close network of
vessels, lies on the surface of the lower end of the femur and upper end of the
tibia around their articular surfaces, and sends numerous offsets into the interior
of the joint. The arteries from which this plexus is formed are the two internal and
two external articular branches of the popliteal, the anastomotica magna, the ter-
minal branch of the profunda, the descending branch from the external circumflex
and the anterior recurrent branch of the anterior tibial.
The Anterior Tibial Artery (A. Tibialis Anterior) (Fig. 435).
The anterior tibial artery commences at the bifurcation of the popliteal at
the lower border of the Popliteus muscle, passes forward between the two
THE ANTERIOR TIBIAL ARTERY 711
heads of the Tibialis posticus, and through the large oval aperture above the
upper border of the interosseous membrane to the deep part of the front of the
leg; it here lies close to the inner side of the neck of the fibula; it then descends on
the anterior surface of the interosseous membrane, gradually approaching the
tibia; and at the lower part of the leg lies on this bone, and then on the anterior
ligament of the ankle to the bend of the ankle-joint, where it lies more superficially,
and becomes the dorsalis pedis.
Relations. — In the upper two-thirds of its extent it rests upon the interosseous
membrane, to which it is connected by delicate fibrous arches thrown across it;
in the lower third, upon the front of the tibia and the anterior ligament of the
ankle-joint. In the upper third of its course it lies between the Tibialis anticus
and Extensor longus digitorum; in the middle third, between the Tibialis anticus
and Extensor proprius hallucis. At the bend of the ankle it is crossed by the
tendon of the Extensor proprius hallucis, and lies between it and the innermost
tendon of the Extensor longus digitorum. It is covered, in the upper two-
thirds of its course, by the muscles which lie on either side of it and by the
deep fascia ; in the lower third, by the integument, anterior annular ligament,
and fascia.
The anterior tibial artery is accompanied by two veins, venae comites, which
lie one on each side of the artery; the anterior tibial nerve, coursing round the
outer side of the neck of the fibula, comes into relation with the outer side of the
artery shortly after it has passed through the opening in the interosseous mem-
brane; about the middle of the leg it is placed superficial to it; at the lower part
of the artery the nerve is generally again on the outer side.
PLAN OF THE RELATIONS OF THE ANTERIOR TIBIAL ARTERY.
In front.
Integument, superficial and deep fasciae.
Anterior tibial nerve.
Tibialis anticus (overlaps it in the upper part of the leg).
Extensor longus digitorum I , , ., ,. ,,, .
Extensor proprius hallucis } (overlap it slightly).
Anterior annular ligament.
Inner side. f \ Outer side.
Tibialis anticus. / Anterior \ Anterior tibial nerve.
Extensor proprius hallucis I Tibial. 1 Extensor longus digitorum.
(crosses it at its lower V J Extensor proprius hallucis.
part).
Behind.
Interosseous membrane.
Tibia.
Anterior ligament of ankle-joint.
Peculiarities in Size. — This vessel may be very small, may be deficient to a greater or less
extent, or may be entirely wanting, its place being supplied by perforating branches from the
posterior tibial or by the anterior division of the peroneal artery.
Course. — The artery occasionally deviates in its course toward the fibular side of the leg,
regaining its usual position beneath the annular ligament at the front of the ankle. In two
instances the vessel has been found to approach the surface in the middle of the leg, being covered
merely by the integument and fascia below that point.
Surface Marking. — Draw a line from the inner side of the head of the fibula to midway
between the two malleoli. In this line take a point one inch and a quarter below the head of
the fibula, and the portion of the line below this point will mark the course of the artery.
Surgical Anatomy. — The anterior tibial artery may be tied in the upper or lower part of
the leg. In the upper part the operation is attentled with great difficulty, on account of the
depth of the vessel from the surface. An incision, about four inches in length, should be made
712
THE BLOOD-VASCULAR SYSTEM
Inferior
external — '
articular.
Inferior internal
articular.
through the integument, midway between the
spine of the tibia and the outer margin of the
fibula, and the deep fascia exposed. The
wound must now be carefully dried, its edges
retracted, and the white line separating the
Tibialis anticus from the Extensor longus
digitorum sought for. When this has been
clearly defined, the deep fascia is to be
divided in this line, and the Tibialis anticus
separated from adjacent muscles with the
handle of the scalpel or a director until the
interosseous membrane is reached. The foot
is to be flexed in order to relax the muscles,
and upon drawing them apart the artery will
be found lying on the interosseous membrane
with the nerve on its outer side or on the top
of the artery. The nerve should be drawn
outward, and the venae comites separated
from the artery and the needle passed
round it.
To tie the vessel in the lower third of the
leg above the ankle-joint an incision about
three inches in length should be made through
the integument between the tendons of the
Tibialis anticus and Extensor proprius hal-
lucis muscles, the deep fascia being divided
to the same extent. The tendon on either
side should be held aside, when the vessel
will be seen lying upon the tibia, with the
nerve on the outer side and one of the vense
comites on either side.
Branches. — The branches of the
anterior tibial artery are — the
Posterior Recurrent Tibial.
Superior Fibular.
Anterior Recurrent Tibial.
Muscular.
Internal Malleolar.
External Malleolar.
The Posterior Recurrent Tibial
(a. recurrens tibialis posterior) is not
a constant branch, and is given off
from the anterior tibial before that
vessel passes through the- interosse-
ous space. It ascends beneath the
Popliteus muscle, which it supplies,
and anastomoses with the lower
articular branches of the popliteal
artery, giving off an offset to the
superior tibio-fibular joint.
The Superior Fibular is some-
times given off from the anterior
tibial, sometimes from the posterior
tibial. It passes outward, round
the neck of the fibula, through the Soleus, which it supplies, and ends in the
substance of the Peroneus longus muscle.
Communicating.
FIG. 435. — Surgical anatomy of the anterior tibial
and dorsalis pedls arteries.
THE ANTERIOR TIBIAL ARTERY 713
The Anterior Recurrent Tibial (a. recurrens tibialis anterior) arises from the
anterior tibial as soon as that vessel has passed through the interosseous space;
it ascends in the Tibialis anticus muscle, and ramifies on the front and sides
of the knee-joint, anastomosing with the articular branches of the popliteal, with
the anastomotica magna, and the external articular branches of the popliteal,
assisting in the formation of the circumpatellar plexus.
The Muscular Branches are numerous; they are distributed to the muscles
which lie on each side of the vessel, some cutaneous branches piercing the deep
fascia to supply the integument, others passing through the interosseous membrane,
and anastomosing with branches of the posterior tibial and peroneal arteries.
The Malleolar Arteries supply the ankle-joint. The internal branch (a. mal-
leolaris anterior medialis) arises about two inches above the articulation, and
passes beneath the tendons of the Extensor proprius hallucis and Tibialis anticus
to the inner ankle, upon which it ramifies, anastomosing with branches of the
posterior tibial and internal plantar arteries and with the internal calcanean
from the posterior tibial. The external branch (a. malleolaris anterior lateralis)
passes beneath the tendons of the Extensor longus digitorum and Peroneous
tertius, and supplies the outer ankle, anastomosing with the anterior peroneal
artery and with ascending branches from the tarsal branch of the dorsalis
pedis. *
The Dorsalis Pedis Artery (A. Dorsalis Pedis) (Figs. 435, 436).
The dorsalis pedis, the continuation of the anterior tibial, passes forward from
the bend of the ankle along the tibial side of the foot to the back part of the first
intermetatarsal space, where it divides into two branches, the dorsalis hallucis and
communicating.
Relations. — This vessel, in its course forward, rests upon the astragalus, navic-
ular, and middle cuneiform bones and the ligaments connecting them, being cov-
ered by the integument and fascia, anterior annular ligament, and crossed near
its termination by the innermost tendon of the Extensor brevis digitorum. On
its tibial side is the tendon of the Extensor proprius hallucis; on its fibular side,
the innermost tendon of the Extensor longus digitorum, and the termination of
the anterior tibial nerve. It is accompanied by two veins.
PLAN OF THE RELATIONS OF THE DORSALIS PEDIS ARTERY.
In front.
Integument and fascia.
Anterior annular ligament.
Innermost tendon of Extensor brevis digitorum.
Tibial side. f Fibular side.
Extensor proprius hallucis. [ Pedis. I Extensor longus digitorum.
J Anterior tibial nerve.
Behind.
Astragalus.
Navicular.
Middle cuneiform.
And their ligaments.
Peculiarities in Size. — The dorsal artery of the foot may be larger than usual, to compen-
sate for a deficient plantar artery; or it may be deficient in its terminal branches, to the toes,
which are then derived from the internal plantar; or its place may be supplied altogether by a
large anterior peroneal artery.
714
THE BLOOD-VASCULAR SYSTEM
Position. — This artery frequently curves outward, lying external to the line between the
middle of the ankle and the back part of the first interosseous space.
Surface Marking. — The dorsalis pedis artery is indicated on the surface of the dorsum of
the foot by a line drawn from the centre of the space between the two malleoli to the back of the
first intermetatarsal space.
Surgical Anatomy. — This artery may be tied, by making an incision through the integu-
ment between two and three inches in length, on the fibular side of the tendon of the Extensor
proprius hallucis, in the interval between it and the inner border of the short Extensor muscle.
The incision should not extend farther forward than the back part of the first intermetatarsal
space, as the artery divides in that situation. The deep fascia being divided to the same extent,
the artery will be exposed, the nerve lying upon its outer side.
ANTERIOR
PERONEAL
ARTERY
EXTERNAL
MALLEOLAR
ARTERY
METATARSAL
ARTERY
DORSAL
INTEROSSCOUS
INTERNAL
MALLEOLAR
ARTERY
DORSALIS PEDIS
ARTERY
COMMUNICATING
ARTERY
DORSALIS
HALLUCIS
ARTERY
FIG. 436.— Diagram of the arteries of the dorsal surface of the foot. (Poirier and Charpy.)
Branches. — The branches of the dorsalis pedis are — the
Cutaneous.
Tarsal.
Metatarsal — Interosseous.
Dorsalis Hallucis.
Communicating.
Cutaneous Branches go to the skin of the dorsum and inner surface of the
foot.
The Tarsal Artery (a. tarsea lateralis) arises from the dorsalis pedis, as that
vessel crosses the navicular bone; it passes in an arched direction outward, lying
upon the tarsal bones, and covered by the Extensor brevis digitorum; it supplies
that muscle and the articulations of the tarsus, and anastomoses with branches
from the metatarsal, external malleolar, peroneal, and external plantar arteries.
THE POSTERIOR TIBIAL ARTERY 715
The Metatarsal (a. arcuata) arises a little anterior to the preceding; it passes
outward to the outer part of the foot, over the bases of the metatarsal bones,
beneath the tendons of the short Extensor, its direction being influenced by its
point of origin; and it anastomoses with the tarsal and external plantar arteries.
This vessel gives off three branches, the dorsal interosseous arteries (aa. meta-
far^raedorsales),-whic\\ pass forward upon the three outer Dorsal interossei mus-
cles, and, in the clefts between the toes, divide into two dorsal collateral branches
for the adjoining toes (aa. digitales dor sales}. At the back part of each inter-
osseous space these vessels receive the posterior perforating branches from the
plantar arch, and at the forepart of each interosseous space they are joined by
the anterior perforating branches from the digital arteries. The outermost
interosseous artery gives off a branch which supplies the outer side of the little
toe.
The Dorsalis Hallucis or the First Dorsal Interosseous (a. dorsalis hallucis) is one
of the terminal branches of the dorsalis pedis. It runs forward along the outer
border of the first metatarsal bone, and at the cleft between the first and second
toes divides into two branches, one of which passes inward, beneath the tendon of
the Extensor proprius hallucis, and is distributed to the inner border of the great
toe; the outer branch bifurcates, to supply the adjoining sides of the great and
second toes.
The Communicating Artery (ramus plantaris profundus), the other terminal
branch of the dorsalis pedis, dips down into the sole of the foot, between the two
heads of the First dorsal interosseous muscle, and inosculates with the termina-
tion of the external plantar artery, to complete the plantar arch. It here gives
off its plantar digital branch, which is named the arteria magna hallucis, or the
princeps hallucis. This artery passes forward along the first interosseous space,
and, after sending a branch along the inner side of the great toe, bifurcates for
the supply of the adjacent sides of the great and second toes.
The Posterior Tibial Artery (A. Tibialis Posterior) (Fig. 434).
The posterior tibial is an artery of large size, which extends obliquely down-
ward from the lower border of the Popliteus muscle, along the tibial side of the
leg, to the fossa between the inner ankle and the heel, where it divides beneath
the origin of the Abductor hallucis, on a level with a line drawn from the point
of the internal malleolus to the centre of the convexity of the heel, into the
internal and external plantar arteries!, At its origin it lies opposite the interval
between the tibia and fibula; as it descends, it approaches the inner side of
the leg, lying behind the tibia, and, in the lower part of its course, is situated
midway between the inner malleolus and the tuberosity of the os calcis.
Relations. — It lies successively upon the Tibialis posticus, the Flexor longus
digitorum, the tibia, and the back part of the ankle-joint. It is covered by the
deep transverse fascia, which separates it above from the Gastrocnemius and
Soleus muscles: at its termination it is covered by the Abductor hallucis muscle.
In the lower third, where it is more superficial, it is covered only by the integu-
ment and fascia, and runs parallel with the inner border of the tendo Achillis.
It is accompanied by two veins and by the posterior tibial nerve, which lies at
first to the inner side of the artery, but soon crosses it, and is, in the greater part
of its course, on its outer side.
PLAN OF THE RELATIONS OF THE POSTERIOR TIBIAL ARTERY.
In front.
Tibialis posticus.
Flexor longus digitorum.
Tibia.
Ankle-joint.
716 THE BLOOD-VASCULAR SYSTEM
Inner side. Outer side.
Posterior tibial nerve, Posterior tibial nerve,
upper third. lower two-thirds.
Behind.
Integument and fascia.
Gastrocnemius.
Soleus.
Deep transverse fascia.
Posterior tibial nerve.
Abductor hallucis.
Behind the inner ankle the tendons and blood-vessels are arranged, under
cover of the internal annular ligament, in the following order, from within out-
ward: First, the tendons of the Tibialis posticus and Flexor longus digitorum,
lying in the same groove, behind the inner malleolus, the former being the most
internal. External to these is the posterior tibial artery, having a vein on either
side: and, still more externally, the posterior tibial nerve. About half an inch
nearer the heel is the tendon of the Flexor longus hallucis.
Peculiarities in Size. — The posterior tibial is not unfrequently smaller than usual, or absent,
its place being supplied by a large peroneal artery which passes inward at the lower end of the
tibia, and either joins the small tibial artery or continues alone to the sole of the foot.
Surface Marking. — The course of the posterior tibial artery is indicated by a line drawn from
a point one inch below the centre of the popliteal space to midway between the tip of the
internal malleolus and the centre of the convexity of the heel.
Surgical Anatomy. — The application of a ligature to the posterior tibial may be required
in cases of wound of the sole of the foot attended with great hemorrhage, when the vessel
should be tied at the inner ankle. In cases of wound of the posterior tibial it will be necessary
to enlarge the opening so as to expose the vessel at the wounded point, excepting where the
vessel is injured by a punctured wound from the front of the leg. In cases of aneurism from
wound of the artery low down, the vessel should be tied in the middle of the leg. But in aneurism
of the posterior tibial high up it would be better to tie the femoral artery.
To tie the posterior tibial artery at the ankle, a semilunar incision, convex backward, should
be made through the integument, about two inches and a half in length, midway between the
heel and the inner ankle or a little nearer the latter. The subcutaneous cellular tissue having been
divided, a strong and dense fascia, the internal annular ligament, is exposed. This ligament is
continuous above with the deep fascia of the leg, covers the vessels and nerves, and is intimately
adherent to the sheaths of the tendons. This having been cautiously divided upon a director,
the sheath of the vessels is exposed, and, being opened, the artery is seen with one of the venae
comites on each side. The aneurism needle should be passed round the vessel from the heel
toward the ankle, in order to avoid the posterior tibial nerve, care being at the same time taken
not to include the vense comites.
The vessel may also be tied in the lower third of the leg by making an incision, about three
inches in length, parallel with the inner margin of the tendo Achillis. The internal saphenous
vein being carefully avoided, the Iwo layers of fascia must be divided upon a director, when the
artery is exposed along the outer margin of the Flexor longus digitorum, with one of its vense
comites on either side and the nerve lying external to it.
To tie the posterior tibial in the middle of the leg is a very difficult operation, on account of
the great depth of the vessel from the surface. The patient being placed in the recumbent posi-
tion, the injured limb should rest on its outer side, the knee being partially bent and the foot
extended, sO as to relax the muscles of the calf. An incision about four inches in length should
then be made through the integument a finger's breadth behind the inner margin of the tibia,
taking care to avoid the internal saphenous vein: The deep fascia having been divided, the
margin of the Gastrocnemius is exposed, and must be drawn aside, and the tibial attachment of
the Soleus divided, a director being previously passed beneath it. The artery may now be
felt pulsating beneath the deep fascia about an inch from the margin of the tibia. The fascia
having been divided, and the limb placed in such a position as to relax the muscles of the calf
as much as possible, the veins should be separated from the artery, and the aneurism needle
passed round the vessel from without inward, so as to avoid wounding the posterior tibial nerve.
Branches. — The branches of the posterior tibial artery are — the
Peroneal. Cutaneous.
Nutrient. Communicating.
Muscular. Internal Calcanean.
Malleolar cutaneous.
THE POSTERIOR TIBIA L ARTERY 717
The Peroneal Artery (a. peronaea) (Fig. 434) lies, deeply seated, along the back
part of the fibular side of the leg. It arises from the posterior tibial about an inch
below the lower border of the Popliteus muscle, passes obliquely outward to the
fibula, and then descends along the inner border of that bone, contained in a
fibrous canal between the Tibialis posticus and the Flexor longus hallucis, or in
the substance of the latter muscle to the lower third of the leg, where it gives off
the anterior peroneal. It then passes across the articulation between the tibia and
fibula to the outer side of the os calcis, where it gives off its terminal branches, the
external calcanean.
Relations. — This vessel rests at first upon the Tibialis posticus, and then, for
the greater part of its course, in a fibrous canal between the origins of the Flexor
longus hallucis and Tibialis posticus, covered or surrounded by the fibres of the
Flexor longus hallucis. It is covered, in the upper part of its course, by the Soleus
and deep transverse fascia; below, by the Flexor longus hallucis.
PLAN OF THE RELATIONS OF THE PERONEAL ARTERY.
In front.
Tibialis posticus.
Flexor longus hallucis.
Outer side. / \ Inner side.
Fibula. [ ^f™,^1 I Flexor longus hallucis.
Flexor longus hallucis.
Behind.
Soleus.
Deep transverse fascia.
Flexor longus hallucis.
Peculiarities in Origin. — The peroneal artery may arise three inches below the Popliteus,
or from the posterior tibial high up, or even from the popliteal,
Its size is more frequently increased than diminished ; and then it either reinforces the poste-
rior tibial by its junction with it, or altogether takes the place of the posterior tibial in the lower
part of the leg and foot, the latter vessel only existing as a short muscular branch. In those
rare cases where the peroneal artery is smaller than usual a branch from the posterior tibial
supplies its place, and a branch from the anterior tibial compensates for the diminished anterior
peroneal artery. In one case the peroneal artery has been found entirely wanting.
The anterior peroneal is sometimes enlarged, and takes the place of the dorsal artery of the
foot.
Branches. — The branches of the peroneal are — the
Muscular. Communicating.
Nutrient. Posterior Peroneal.
Anterior Peroneal. External Calcanean.
Muscular Branches. — The peroneal artery in its course gives off branches to the
Soleus, Tibialis posticus, Flexor longus hallucis, and Peronei muscles.
The Nutrient Artery (a. nutritia fibulae) supplies the fibula.
The Anterior Peroneal (ramus perforans) (Fig. 436) pierces the interosseous
membrane, about two inches above the outer malleolus, to reach the forepart of
the leg, and, passing down beneath the Peroneus tertius to the outer ankle, ramifies
on the front and outer side of the tarsus, anastomosing with the external malleolar
and tarsal arteries.
The Communicating (ramus communicans) is given off from the peroneal about
an inch from its lower end, and, passing inward, joins the communicating branch
of the posterior tibial.
718
THE BLOOD-VASCULAR SYSTEM
The Posterior Peroneal passes down behind the outer ankle to the back of the
external malleolus, to terminate in branches which ramify on the outer surface
and back of the os calcis.
External Calcanean (ramus calcaneus later alls) are the terminal branches of the
peroneal artery; they pass to the outer side of the heel, and communicate with the
external malleolar, and, on the back of the heel, with the internal calcanean
arteries.
Cutaneous Branches come from the posterior tibial and supply the skin of
the inner side and back of the leg.
The Nutrient Artery of the tibia (a. nutricia tibiae) arises from the posterior
tibial near its origin, and, after supplying a few muscular branches, enters the
nutrient canal of that bone, which it traverses obliquely from above downward.
This is the largest nutrient artery of bone in the body.
The Muscular Branches of the posterior tibial are distributed to the Soleus and
deep muscles along the back of the leg.
The Communicating Branch (ramus communicans) , to join a similar branch
of the peroneal, runs transversely across the back of the tibia, about two inches
above its lower end, passing beneath the Flexor longus hallucis.
The Malleolar or Internal Malleolar (a. malleolaris posterior medialis) lies
upon the tibia, sends branches over the inner ankle, and anastomoses with the
inner malleolar branch of the anterior tibial.
The Internal Calcanean (rami calcanei mediales) are several large arteries
which arise from the posterior tibial just before its division: they are distributed
Communicating
branch of
dorsalis pedis.
Its digital
branches.
FIG. 437. — The plantar arteries. Superficial view.
FIG. 438. — The plantar arteries. Deep view.
to the fat and integument behind the tendo Achillis and about the heel, and to the
muscles on the inner side of the sole, anastomosing with the peroneal and internal
malleolar, and, on the back of the heel, with the external calcanean arteries.
The Internal Plantar Artery (a. plantaris medialis) (Figs. 437 and 438), much
smaller than the external, passes forward along the inner side of the foot. It is
THE POSTERIOR TIBIAL ARTERY 719
at first situated above1 the Abductor hallucis, and then between it and the Flexor
brevis digitorum, both of which it supplies. At the base of the first metatarsal
bone, where it has become much diminished in size, it passes along the inner border
of the great toe, inosculating with its digital branch. Small superficial digital
branches (ramus superficialis} accompany the digital branches of the medial
plantar nerve and join the plantar digital arteries of the three inner spaces. In
addition, this vessel gives off numerous cutaneous branches.
The External Plantar Artery (a. plantaris lateralis) (Figs. 437 and 438), much
larger than the internal, passes obliquely outward and forward to the base of the
» fifth metatarsal bone. It then turns obliquely inward to the interval between
the bases of the first and second metatarsal bones, where it anastomoses with
the communicating branch from the dorsalis pedis artery, thus completing the
plantar arch (arcm plantaris} (Fig. 438). As this artery passes outward, it is first
placed between the os calcis and Abductor hallucis, and then between the Flexor
brevis digitorum and Flexor accessorius, and as it passes forward to the base of
the little toe it lies more superficially between the Flexor brevis digitorum and
Abductor minimi digiti, covered by the deep fascia and integument. The remain-
ing portion of the vessel is deeply situated : it extends from the base of the meta-
tarsal bone of the little toe to the back part of the first interosseous space, and
forms the plantar arch; it is convex forward, lies upon the Interossei muscles
opposite the tarsal ends of the metatarsal bones, and is covered by the Adductor
obliquus hallucis, the flexor tendons of the toes, and the Lumbricales.
Surface Marking. — The course of the internal plantar artery is represented by a line
drawn from the mid-point between the tip of the internal malleolus and the centre of the con-
vexity of the heel to the middle of the under surface of the great toe; the external plantar by
a line from the same point to within a finger's breadth of the tuberosity of the fifth metatarsal
bone. The plantar arch is indicated by a line drawn from this point — i. e., a finger's breadth
internal to the tuberosity of the fifth metatarsal bone transversely across the foot to the back of
the first interosseous space.
Surgical Anatomy. — Wounds of the plantar arch are always serious, on account of the
depth of the vessel and the important structures which must be interfered with in an attempt
to ligate it. They must be treated on similar lines to those of wounds of the palmar arches
(see page 667). Delorme has shown that the plantar arch may be ligated from the dorsum of the
foot in almost any part of its course by removing a portion of one of the three middle metatarsal
bones.
Branches. — The plantar arch, besides distributing numerous branches to the
muscles, integument, and fasciae in the sole, gives off the following branches:
Posterior Perforating. Digital.
The Posterior Perforating (rami perforantes posteriores) are three small branches
which ascend through the back part of the three outer interosseous spaces, between
the heads of the Dorsal interossei muscles, and anastomoses with the interosseous
branches from the metatarsal artery.
The Digital Branches (aa. metatarseae plantares) are four in number, and supply
the three outer toes and half the second toe. It will be remembered that the
irteria princeps hallucis is the plantar digital branch of the communicating
irms in the first interosseous space and supplies the adjacent sides of the great
and little toes. The first digital branch of the plantar arch passes outward
from the outer side of the plantar arch, and is distributed to the outer side of the
little toe, passing in its course beneath the Abductor and short Flexor muscles,
e second, third, and fourth run forward along the interosseous spaces, and on
arriving at the clefts between the toes divides into collateral digital branches (aa/
digitales plantares), which supply the adjacent sides of the three outer toes and
1 This refers to the erect position of the body. In the ordinary position for dissection the artery is deeper
than the muscle.
720 THE BLOOD-VASCULAR SYSTEM
the outer side of the second. At the bifurcation of the toes each digital artery
sends upward, through the forepart of the corresponding interosseous space, a
small branch which inosculates with the interosseous branches of the metatarsal
artery. These are the anterior perforating branches (rami perforantes anterior es).
From the arrangement already described of the distribution of the vessels to
the toes it will be seen that both sides of the three outer toes and the outer side
of the second toe are supplied by branches from the plantar arch; both sides of
the great toe and the inner side of the second are supplied by the communicating
branch of the dorsalis pedis.
THE VEINS.
THE Veins are the vessels which serve to return the blood from the capillaries
of the different parts of the body to the heart. They consist of two distinct sets
of vessels, the pulmonary and systemic veins, and an appendage to the systemic,
the portal system.
The Pulmonary Veins are concerned in the circulation in the lungs. Unlike
other vessels of this kind, they contain arterial blood, which they return from the
lungs to the left auricle of the heart. The pulmonary veins are four in number.
A
A
FIG. 439. — Valves of a vein. In the lower part
of the figure is seen the parietal valves; the upper
part shows the mouth of a vein guarded by a valve.
(Poirier and Charpy.)
FIG. 440. — Collateral anastomosis of veins. The arrows
indicate the direction of the flow of blood (schematic).
(Poirier and Charpy.)
The Systemic Veins are concerned in the general circulation; they return the
venous blood from the body generally to the right auricle of the heart. The sys-
temic veins are the precava or superior vena cava, the postcava or inferior vena cava,
and the coronary sinus.
The Portal Vein and its radicles constitute the portal system. The portal system
is in reality an appendage to the systemic venous system. It is confined to the
abdominal cavity, returning the venous blood from the viscera of digestion, and
carrying it to the liver by a single trunk of large size, the portal vein or vena portae.
This vessel ramifies in the substance of the liver and breaks up into a minute
46 ( 721 )
722
THE BLOOD-VASCULAR SYSTEM
fif—- j-^^i
network of capillaries. These capillaries then re-collect to form the hepatic veins,
by which the blood is conveyed to the postcava.
The veins, like the arteries, are found in nearly every tissue of the body. They
commence by minute plexuses which receive the blood from the capillaries. The
branches which have their commencement in these plexuses unite together
into trunks, and these, in their passage toward the heart, constantly increase in
size as they receive tributaries or join other veins. The veins are larger and
altogether more numerous than the arteries; hence the entire capacity of the
venous system is much greater than that of the arterial, the pulmonary veins
excepted, which only slightly exceed in capacity the pulmonary arteries. From
the combined area of the smaller venous branches being greater than the main
trunks, it results that the venous system represents a cone, the summit of which
corresponds to the heart, its base to the circumference of the body. In form the
veins are perfectly cylindrical, like the arteries, their walls being collapsed when
empty, and the uniformity of their surface being interrupted at intervals by slight
constrictions, which indicate the existence of valves in their interior (Fig. 439) .
They usually retain, however, about the same calibre as long as they receive no
branches, but not so uniformly as do the arteries.
The veins communicate very freely with one another (Fig. 441), especially in
certain regions of the body, and this communication exists between the larger
trunks as well as between the smaller
branches. Thus, in tha cavity of the
cranium and between the veins of the
neck, where obstruction would be at-
tended with imminent danger to the
cerebral -venous system, we find that
the sinuses and larger veins have large
and very frequent anastomoses (Fig.
U\\ ^^^^^^^^^^^ f A 1 440). The same free communication
I ^^S, ^^^ IT if exists between the veins throughout
the whole extent of the spinal canal,
and between the veins composing the
various venous plexuses in the abdo-
men and pelvis, as the spermatic,
uterine, vesical, and prostatic.
Veins have thinner walls than
arteries, the difference in thickness
being due to the small amount of
elastic and muscular tissues which
the veins contain. The superficial veins usually have thicker coats than the deep
veins, and the veins of the lower limb are thicker than those of the upper.
Histology of the Veins. — As previously stated, capillaries enter into venules
or precapillary veins. The venules empty into larger veins. Vein walls are much
thinner than arterial walls. A vein has a much thinner media and much less
elastic tissue than an artery, and a very strongly developed adventitia. The
intima is a connective-tissue layer containing a small number of elastic fibres
and lined with endothelium. The media contains some circular muscle fibres
and some fine elastic fibres. In some veins the media is thoroughly well devel-
oped (veins of the lower extremities), in others it is practically absent (veins of
the retina, of the pia, of bone, the precava). The adventitia is dense and strong,
and is composed of connective-tissue elastic fibres and non-striated muscle fibres
placed longitudinally. Fig. 442 shows a transverse section of part of the wall of a
vein. The vein valves (Fig. 439) are composed of intima and contain elastic fibres.
The large veins and the veins of medium size possess vasa vasorum, in the adven-
FIG. 44i.— The venous circle of Braune (schematic),
°ethe ^^'^ of the blood current-
THE PULMONARY VEINS
723
titia and to some extent in the media. The walls of veins contain vasomotor nerves.
"Small blood-vessels are often surrounded by lymph capillaries and sometimes by
endothelium-lined spaces which are in communication with the lymphatic system.
These are called perivascular lymph spaces."1
The systemic veins are subdivided into three sets: superficial, deep, and sinuses.
The Superficial or Cutaneous Veins are found between the layers of the super-
ficial fascia, immediately beneath the integument; they return the blood from
these structures, and communicate with the deep veins by perforating the deep
fascia.
Endothdial and
S subendothelial
'layers.
Elastic layer.
— Middle coat.
•—Outer coat.
FIG. 442. — Transverse section of part of the wall of one of the posterior tibial veins. (After Schiifer.)
The Deep Veins accompany the arteries, and are usually enclosed in the same
sheath with those vessels. With the smaller arteries — as the radial, ulnar, brachial,
tibial, and peroneal — they exist generally in pairs, one lying on each side of the
vessel, and are called venae comites. The larger arteries — as the axillary, sub-
clavian, popliteal, and femoral — have usually only one accompanying vein. In
certain organs of the body, however, the deep veins do not accompany the
arteries; for instance, the veins in the skull and spinal canal, the hepatic veins in
the liver, and the larger veins returning blood from the osseous tissue.
Sinuses are venous channels which, in their structure and mode of distribution,
differ altogether from the veins. They are found only in the interior of the skull,
and consist of channels formed by a separation of the two layers of the dura,
their outer coat consisting of fibrous tissue, their inner of an endothelial layer
continuous with the lining membrane of the veins.
THE PULMONARY VEINS (V. PULMONALES) (Fig. 443).
The pulmonary veins return the arterial blood from the lungs to the left auricle
of the heart. They are four in number, two for each lung. The pulmonary veins
differ from other veins in several respects: 1. They carry arterial instead of
venous blood. 2. They are destitute of valves. 3. They are only slightly larger
than the arteries they accompany. 4. They accompany those vessels singly.
They commence in a capillary network upon the walls of the air-cells, where they
are continuous with the capillary ramifications of the pulmonary artery, and,
uniting together, form one vessel for each lobule. These vessels, uniting suc-
cessively, form a single trunk for each lobe, three for the right and two for the
left lung. The vein from the middle lobe of the right lung generally unites with
that from the upper lobe, forming two trunks on each side, which open separately
into the left auricle. Occasionally they remain separate; there are then three
Histology and Microscopic Anatomy. By Szymonowicz and MacCallum.
724
THE BLOOD -VASCULAR SYSTEM
veins on the right side. Not unfrequently the two left pulmonary veins terminate
by a common opening.
Within the lung, the branches of the pulmonary artery are in front, the veins
behind, and the bronchi between the two.
At the root of the lung, the veins are in front, the artery in the middle, and the
bronchus behind.
ENTRANCE OF
t VENA AZYGOS
BRANCH OF PUL-
MONARY ARTERY
FIG. 443. — Pulmonary veins, seen in a dorsal view of the heart and lungs. The left lung is pulled to the
left, and the right lung has been partly cut away to show the ramifications of the air-tubes and blood-vessels.
(Testut.)
Within the pericardium, their anterior surface is invested by the serous layer
of this membrane. The right pulmonary veins pass behind the right auricle and
ascending aorta and precava; the left pass in front of the thoracic aorta with the
left pulmonary artery.
THE SYSTEMIC VEINS.
The systemic veins may be arranged into three groups: 1. Those of the head
and neck, upper extremity, and thorax, which terminate in the precava. 2. Those
of the lower extremity, abdomen, and pelvis, which terminate in the postcava. 3.
The cardiac veins, which open directly into the right auricle of the heart.
VEINS OF THE HEAD AND NECK.
The veins of the head and neck may be subdivided into three groups: 1. The
veins of the exterior of the head and face. 2. The veins of the neck. 3. The veins
of the diploe and interior of the cranium.
VEIXS OF THE EXTERIOR OF THE HEAD AND FACE 725
Veins of the Exterior of the Head and Face (Fig. 444).
The veins of the exterior of the head and face are — the
Frontal.
Supraorbital.
Angular.
Facial.
Temporal.
Internal Maxillary.
Temporo-m axillary.
Posterior Auricular.
Occipital.
The Frontal Vein (v. frontalis) commences on the anterior part of the skull by
a venous plexus which communicates with the anterior tributaries of the temporal
vein. The veins converge to form a single trunk, which runs downward near the
Frontal
Communicating
branch with
ophthalmic vein.
Angular.
Anterior division
of the temporo-
maxillary.
Anterior
'facial.
Common
•facial
Lingual.
LaryngeaL
FIG. 444. — Veins of the head and neck.
middle line of the forehead parallel with the vein of the opposite side, and unites
with it at the root of the nose by a transverse branch called the nasal arch (v. naso-
frontalis). Occasionally the frontal veins join to form a single trunk, which
726 THE BLOOD -VASCULAR SYSTEM
bifurcates at the root of the nose into the two angular veins. At the root of
the nose the veins diverge and join the supraorbital vein, at the inner angle of
the orbit, to form the angular vein.
The Supraorbital Vein (v. supraorbitalis) commences on the forehead, com-
municating with the anterior temporal vein, and runs downward and inward,
superficial to the Occipito-frontalis muscle, receiving tributaries from the neigh-
boring structures, and from the frontal vein of the diploe, and joins the frontal
vein at the inner angle of the orbit to form the angular vein.
The Angular Vein (v. angularis), formed by the junction of the frontal and
supraorbital veins, runs obliquely downward and outward on the side of the root
of the nose, and receives the veins of the ala nasi on its inner side and the superior
palpebral veins on its outer side; it moreover communicates with the ophthalmic
vein, thus establishing an important anastomosis between this vessel and the
cavernous sinus. Some small veins from the dorsum of the nose terminate in the
nasal arch.
The Anterior Facial Vein (v. facialis anterior) commences at the side of the
root of the nose, being a direct continuation of the angular vein, which is itself
formed by the union of the frontal vein and the supraorbital vein. It lies behind
and follows a less tortuous course than the facial artery. It passes obliquely
downward and outward, beneath the Zygomaticus major and minor muscles,
descends along the anterior border of the Masseter, crosses over the body of the
lower jaw, with the facial artery to beneath the angle, and unites with the anterior
division of the temporo-maxillary vein (v. facialis posterior) to form the common
facial vein.
The Common Facial Vein (v. facialis communis) is formed by the union of the
anterior facial and the anterior division of the temporo-maxillary vein, just beneath
the angle of the niandible. The vein is covered by the Platysma myoid muscle,
runs downward and backward beneath the Sterno-cleido-mastoid muscle, crosses
the external carotid artery, and empties into the internal jugular vein at the level
of the hyoid line. It receives a large branch at the anterior border of the Sterno-
cleido-mastoid muscle, which comes from the anterior jugular vein in the supra-
sternal fossa.
Tributaries of the Anterior and Common Facial Veins. — The anterior facial vein
receives, near the angle of the mouth, communicating tributaries of considerable
size, the deep facial or anterior internal maxillary vein, from the pterygoid
plexus. It is also joined by the inferior palpebral, the superior and inferior
labial veins, the buccal veins from the cheek, and the masseteric veins. The
common facial vein receives the submental; the inferior palatine, which returns
the blood from the plexus round the tonsil and soft palate; the submaxillary
vein, which commences in the submaxillary gland; and, generally, the ranine
vein.
Surgical Anatomy. — There are some points about the facial vein which render it of great
importance in surgery. It is not so flaccid as are most superficial veins, and, in consequence of
this, remains more patent when divided. It has, moreover, no valves. It communicates freely
with the intracranial circulation, not only at its commencement by its tributaries, the angular
and supraorbital veins, communicating with the ophthalmic vein, a tributary of the cavernous
sinus, but also by its deep branch, which communicates through the pterygoid plexus with the
cavernous sinus by branches which pass through the foramen ovale and foramen lacerum
medium. These facts have an important bearing upon the surgery of some diseases of the
face, for on account of its patency the facial vein favors septic absorption, and therefore any
phlegmonous inflammation of the face following a poisoned wound is liable to set up thrombosis
in the facial vein, and detached portions of the clot may give rise to purulent foci in other
parts of the body. And on account of its communications with the cerebral sinuses these
thrombi are apt to extend upward into them and so induce a fatal issue.
VEINS OF THE EXTERIOR OF THE HEAD AND FACE 727
The Superficial Temporal Vein (vv. temporales super fi dales) commences by a
minute plexus on the side and vertex of the skull, which communicates with the
frontal and supraorbital veins in front, the corresponding vein of the opposite
side, and the posterior auricular and occipital veins behind. From this network
anterior and posterior branches are formed which unite above the zygoma, form-
ing the trunk of the vein. The trunk is joined in this situation by a large vein,
the middle temporal (v. temporalis media), which receives blood from the sub-
stance of the Temporal muscle and pierces the fascia at the upper border of
the zygoma. The junction of the superficial temporal and the middle temporal
veins forms the common temporal vein (v. temporalis communis), which descends
between the external auditory meatus and the -condyle of the jaw, enters the
substance of the parotid gland, and unites with the internal maxillary vein to form
the temporo-maxillary vein.
Tributaries. — The common temporal vein receives in its course some parotid
veins, an articular branch from the articulation of the jaw, anterior auricular veins
from the external ear, and a vein of large size, the transverse facial (v. transversa
faciei), from the side of the face. The middle temporal vein, previous to its junc-
tion with the temporal vein, receives a branch, the orbital vein (v. crbitalis), which
is formed by some external palpebral branches, and passes backward between
the layers of the temporal fascia.
The Pterygoid Plexus (plexus pterygoideus) and the Internal Maxillary
Vein. — The internal maxillary vein is a vessel of considerable size, receiving
branches which correspond with those of the internal maxillary artery. Thus it
receives the two medidural or middle meningeal veins, the deep temporal, the
pterygoid, masseteric, buccal, and alveolar veins, some palatine veins, the spheno-
palatine and the inferior dental veins. The deep temporal veins (vv. temporales
profundae) come to the pterygoid plexus from the temporal muscle. These branches
form a large plexus, the pterygoid plexus, which is placed between the Temporal
and External pterygoid and partly between the Pterygoid muscles. This plexus is
a tributary of the internal maxillary vein, and communicates very freely with the
facial vein and with the cavernous sinus by branches through the foramen Vesalii,
foramen ovale, and foramen lacerum medium, at the base of the skull. The trunk
of the internal maxillary vein comes from the plexus, then passes backward behind
the neck of the lower jaw, and unites with the temporal vein, forming the temporo-
maxillary vein.
The Temporo-maxillary Vein (v. facialis posterior), formed by the union of
the superficial temporal and internal maxillary veins, descends in the substance of
the parotid gland on the outer surface of the external carotid artery, between the
ramus of the jaw and the Sterno-mastoid muscle, and divides into two branches,
an anterior, which passes inward to join the facial vein, and a posterior, which
is joined by the posterior auricular vein and becomes the external jugular.
The Posterior Auricular Vein (v. auricularis posterior) commences upon the
side of the head by a plexus which communicates with the tributaries of the tem-
poral and occipital veins. The vein descends behind the external ear and joins
the posterior division of the temporo-maxillary vein, forming the external jugular.
This vessel receives the stylo-mastoid vein and some tributaries from the back
part of the external ear.
The Occipital Vein (v. occipitalis) commences at the back part of tiie vertex
of the skull by a plexus in a similar manner to the other veins. From the plexus
comes one or two veins, which follow the course of the occipital artery, passing
deeply beneath the muscles of the back part of the neck, and terminating in the
suboccipital triangle by becoming continuous with the posterior vertebral vein.
Sometimes they are more superficial, and in this case they are tributaries of the
728 THE BLOOD -VASCULAR SYSTEM
external jugular vein. As the outermost occipital vein passes across the mastoid
portion of the temporal bone, it receives the mastoid vein, which thus establishes
a communication with the lateral sinus.
The Veins of the Neck (Fig. 444).
The veins of the neck, which return the blood from the head and face, are — the
External Jugular. Anterior Jugular.
Posterior External Jugular. Internal Jugular.
Vertebral.
The External Jugular Vein (v. jugularis externa) receives the greater part
of the blood from the exterior of the cranium and deep parts of the face, being
formed by the junction of the posterior division of the temporo-maxillary and
the posterior auricular veins. It commences in the substance of the parotid gland,
on a level with the angle of the lower jaw, and runs perpendicularly down the neck
in the direction of a line drawn from the angle of the jaw to the middle of the
clavicle. In its course it crosses the Sterno-mastoid muscle, and runs parallel with
its posterior border as far as its attachment to the clavicle, where it perforates the
deep fascia, and terminates in the subclavian vein, on the outer side of, or in front
of, the Scalenus anticus muscle. In the neck it is separated from the Sterno-
mastoid by the investing layer of the deep cervical fascia, and is covered by the
Platysma, the superficial fascia, and the integument. This vein is crossed about
its middle by the superficialis colli nerve, and throughout the upper half of its
course is accompanied by the auricularis magnus nerve. The external jugular vein
varies in size, bearing an inverse proportion to that of the other veins of the neck;
it is occasionally double. It is provided with two pairs of valves, the lower pair
being placed at its entrance into the subclavian vein, the upper pair in most cases
about an inch and a half above the clavicle. The portion of vein between the two
sets of valves is often dilated, and is termed the sinus. These valves do not prevent
the regurgitation of the blood or the passage of injection from below upward.1
Tributaries. — This vein receives the occipital occasionally, the posterior external
jugular, and, near its termination, the suprascapular and transverse cervical veins.
It communicates with the anterior jugular, and, in the substance of the parotid,
receives a large branch of communication from the internal jugular.
The Posterior External Jugular Vein (v. jugularis posterior] commences in
the occipital region, and returns the blood from the integument and superficial
muscles in the upper and back part of the neck, lying between the Splenius and
Trapezius muscles. It runs down the back part of the neck, and opens into the
external jugular just below the middle of its course.
The Anterior Jugular Vein (v. jugularis anterior) commences near the
hyoid bone from the convergence of the inferior coronary, the submental and the
mental veins, and communicating branches. It passes down between the median
line and the anterior border of the Sterno-mastoid, and at the lower part of the
neck passes beneath that muscle to open into the termination of the external
jugular or into the subclavian vein (Fig. 465). This vein varies considerably in
size, bearing almost always an inverse proportion to the external jugular. Most
frequently there are two anterior jugulars, a right and left, but occasionally only
one. This vein receives some laryngeal veins, and occasionally a small thyroid
vein. Just above the sternum the two anterior jugular veins communicate by a
1 The student may refer to an interesting paper by Dr. Struthers, " On Jugular Venesection in Asphyxia.
Anatomically and Experimentally Considered, including the Demonstration of Valves in the Veins of the Neck,
in the Edinburgh Medical Journal for November, 1856. — ED. of 15th English edition.
THE VEINS OF THE NECK
729
transverse trunk, which receives tributaries from the inferior thyroid veins. It
also communicates with the internal jugular. There are no valves in this vein.
The Internal Jugular Vein (v. jugularis interna) collects the blood from
the interior of the cranium, from the superficial parts of the face, and from the
neck. It commences just external to the jugular foramen, at the base of the skull,
being formed by the coalescence of the lateral and inferior petrosal sinuses (Fig.
458). At its origin it is somewhat dilated, and this dilatation is called the sinus
or gulf of the internal jugular vein (bulbus v. jugularis superior). It runs down the
side of the neck in a vertical direction, lying at first on the outer side of the internal
carotid artery, and then on the outer side of the common carotid artery, and at
the root of the neck unites with the subclavian vein to form the innominate vein.
Just before its termination it is distinctly dilated (bulbus v. jugularis inferior). The
HYPOGLOSSAL
FIG. 445. — Veins of the tongue. (Testut, modified from Hirschfeld.)
internal jugular vein, at its commencement, lies upon the Rectus capitis lateralis,
and behind the internal carotid artery and the nerves passing through the jugular
foramen; lower down, the vein and artery lie upon the same plane, the glosso-
pharyngeal and hypoglossal nerves passing forward between them; the vagus
descends between and behind them in the same sheath, and the accessory passes
obliquely outward, behind or in front of the vein. At the root of the neck the vein
of the right side is placed at a little distance from the artery; on the left side it
usually lies over the artery at its lower part. The right internal jugular vein crosses
the first part of the subclavian artery. The internal jugular vein is of considerable
size, but varies in different individuals, the left one being usually the smaller.
It is provided with a pair of valves, which are placed at its point of termination
or from one-half to three-quarters of an inch above it.
Tributaries. — This vein receives in its course the facial, lingual, pharyngeal,
superior, and middle thyroid veins. A branch from the cochlea opens into the
sinus of the internal jugular vein. A venous plexus from the lateral sinus (plexus
venosus caroticus internus) surrounds the internal carotid artery in the carotid
canal and empties into the internal jugular vein. At its point of junction with the
common facial vein it becomes increased in size. (See Facial Veins, p. 726.)
The Lingual Veins (vv. linguale) (Fig. 445) commence on the dorsum, sides, and
under surface of the tongue, and, passing backward, following the course of the
lingual artery and its branches, terminate in the internal jugular. Sometimes the
ranine vein, which is a branch of considerable size commencing below the tip of the
730
THE BLOOD -VASCULAR SYSTEM
tongue, joins the lingual. Generally, however, it passes backward, crosses the
Hyo-glossus muscle in company with the hypoglossal nerve, and joins the internal
jugular. The lingual vein receives the sublingual vein and the dorsalis linguae veins.
The Pharyngeal Veins (vv. pharync/eae) vary in number. They commence in a
minute plexus, the pharyngeal plexus (plexus pharyngeus), at the back part and
sides of the pharynx, and, after receiving meningeal tributaries, the dural or
meningeal veins (vv. meningea), the Vidian veins (vv. canalis pierygoidei [Vidii]),
and the spheno-palatine veins, terminate in the internal jugular. They occasion-
ally open into the facial, lingual, or superior thyroid vein.
SUBMENTAL
INFERIOR
PALAT
STERNO-CLEIDO-
MASTOID MUSCLE
SUPERIOR
THYROID'
TEMPORO-
M AXILLARY
TRANSVERSE
VICAL
SUBCLAVIAN
FIG. 446. — The veins of the neck, viewed from in front. (Spalteholz.)
The Superior Thyroid Vein (v. thyreoidea superioris) (Fig. 446) commences in the
substance and on the surface of the thyroid gland by tributaries corresponding
with the branches of the superior thyroid artery, and terminates in the upper
part of the internal jugular vein. It receives the superior laryngeal and crico-
thyroid veins. Some anatomists teach that there are two superior thyroid veins
on each side, the upper vein being the one just considered, the lower vein being
the one usually pointed out as the middle thyroid.
The Middle Thyroid Vein (Fig. 448) collects the blood from the lower part of the
lateral lobe of the thyroid gland, and, being joined by some veins from the larynx
and trachea, terminates in the lower part of the internal jugular vein.
Often in
731
place of the middle thyroid vein there are two veins, the superior and inferior
accessory thyroid. These veins pass into the internal jugular.
FIG. 447. — Diagram showing common arrangement of thyroid veins. (Kocher.)
INFERIOR
THYROID
VEIN
INFERIOR
THYROID
VEIN
FIG. 448. — The fascia and middle thyroid veins. The veins here designated the inferior thyroid are called by
Kocher the thyreoidea ima. (Poirier and Charpy.)
Veins of the Thyroid Gland1 (Fig. 447) . — On the surface of the thyroid glands
the veins form a plexus between the capsule and the gland. A number of veins
1 See Kocher's description in Langenbeck's Arch. f. klin. Chir., vol. xxix., and James Berry's description in his
treatise on Diseases of the Thyroid Gland.
732 THE BLOOD -VASCULAR SYSTEM
penetrate the capsule and pass into adjacent trunks. The most important veins
coming from the gland are the superior, middle, and inferior thyroids (or instead
of the middle thyroid the superior and inferior accessory thyroid) and the
thyreoidea ima.
The superior thyroid vein emerges from the summit of the superior horn of the
gland, runs along by the superior thyroid artery, and terminates in the internal
jugular vein. A large branch which passes along the inner margin of the upper
horn and across the upper surface of the isthmus joins the superior thyroid veins
of each side. The middle thyroid vein when present emerges from the side of the
gland and empties into the internal jugular. This single vein may be replaced by
two veins, the superior and inferior accessory thyroid veins. The superior vein
emerges from the outer surface of the upper horn somewhat below the apex. The
inferior vein comes from the posterior and inferior portion of the gland. Both
empty into the internal jugular. The lower surface of the isthmus and the inner
side of each inferior horn is drained by two veins. Each vein is called the thy-
reoidea ima (Kocher). The left vein empties into the left innominate vein. The
right vein empties into either the right or left innominate vein. These veins may
be very small, may be absent, or may join and form one vein which empties into
the left innominate. An inferior thyroid is often also present. It comes from the
outer portion of the inferior horn of the gland and empties into the innominate vein,
The facial and occipital veins have been described on pages 726 and 727.
Surgical Anatomy. — The internal jugular vein occasionally requires ligature in cases of septic
thrombosis of the lateral sinus from suppuration in the middle ear. This is done in order to
prevent septic emboli being carried into the general circulation. This operation has been
performed in a number of cases, with satisfactory results. The cases are generally those of
chronic disease of the middle ear, with discharge of pus which perhaps has existed for many
years. The patient is seized with acute septic inflammation, spreading to the mastoid cells,
and, consequent on this, septic thrombosis of the lateral sinus extending to the internal jugular
vein. Such cases are always extremely grave, for there is danger that a portion of the septic
clot will be detached and cause septic embolism in the thoracic viscera. If th^ombo-phlebitis
of the sinus is suspected the mastoid should be opened and cleansed and the sinus should be at
once exposed and explored. If the sinus is found to be thrombosed the surgeon should at
once proceed to ligate the internal jugular vein, by an incision along the anterior border of the
sterno-mastoid, the centre of which is on a level with the greater cornu of the hyoid bone. The
vein should be ligated in two places and divided between. After the vessel has been secured
and divided the lateral sinus is to be thoroughly cleared out, and, by removing the ligature from
the upper end of the divided vein, all septic clots may be removed by syringing from the sinus
through the vein. If hemorrhage occurs from the distal end of the sinus, it can be arrested by
careful plugging with antiseptic gauze.
The thyroid veins are small vessels when the gland is of normal size, but become enormous
when the gland is much enlarged.
In the operation of thyroidectomy the veins as well as the arteries are ligated before the gland,
or rather before one lobe of it is extirpated.
The Vertebral Vein (v. vertebralis] (Fig. 449) commences by numerous small
veins from the intraspinal venous plexuses (plexus venosi vertebrates'); these pass
outward and enter the foramen in the transverse process of the atlas, and descend,
forming a dense plexus around the vertebral artery in the canal formed by the
foramina in the transverse processes of the cervical vertebrse. The vessels of this
plexus unite at the lower part of the neck into two main trunks, one of which
emerges from the foramen in the transverse process of the sixth cervical vertebra,
and the other through that of the seventh. Uniting, these two trunks form a
single vessel which terminates at the root of the neck in the back part of the
innominate vein near its origin, its mouth being guarded by a pair of valves.
On the right side it crosses the first part of the subclavian artery.
Tributaries. — The vertebral vein receives in its course a vein from the inside
of the skull through the posterior condyloid foramen. It anastomoses with the
THE VEINS OF THE DIPLOE
733
occipital vein and receives muscular veins from the muscles in the prevertebral
region; dorsi-spinal veins, from the back part of the cervical portion of the spine;
meningo-rachidian veins, from the interior of the spinal canal; the anterior and
posterior vertebral veins; and close to its termination it is joined by a small vein
from the first intercostal space which accompanies the superior intercostal artery.
The Anterior Vertebral or Anterior Deep Cervical Vein commences in a plexus
around the transverse processes of the upper cervical vertebrae, descends in com-
pany with the ascending cervical artery between the Scalenus anticus and Rectus
capitis anticus major muscles, and opens into the vertebral vein just before its
termination.
VERTEBRAL
POSTERIOR
DEEP
CERVICAL
POSTERIOR
EXTERNAL
JUGULAR
VERTEBRAL
ASCENDING
CERVICAL
FIG. 449. — The vertebral vein. (Poirier and Charpy.)
The Posterior Vertebral or Posterior Deep Cervical Vein (v. cervicalis profunda)
(Fig. 449) accompanies the profunda cervicis artery, lying between the Corn-
plexus and Semispinalis colli. It commences in the suboccipital region by com-
municating branches from the occipital vein and tributaries from the deep muscles
at the back of the neck. It receives tributaries from the plexuses around the spinous
processes of the cervical vertebrae, and terminates in the lower end of the vertebral
vein.
The Veins of the Diploe (Venae Diploicae) (Fig. 450).
The diploe of the cranial bones is channelled in the adult by a number of
tortuous canals, the diploic canals or canals of Breschet (canales diploici [Brescheti]) ,
which are lined by a more or less complete layer of compact tissue. The veins
they contain are large and capacious, their walls being thin, and formed only of
endothelium resting upon a layer of elastic tissue, and they present at irregular
intervals pouch -like dilatations, or culs-de-sac, which serve as reservoirs for the
blood. These are the veins of the diploe ; they can only be displayed by removing
the outer table of the skull.
In adult life, as long as the cranial bones are distinct and separable, these
veins are confined to the particular bones; but in old age, when the sutures are
734 THE BLOOD-VASCULAR SYSTEM
united, they communicate with each other and increase in size. These vessels
communicate, in the interior of the cranium, with the dural veins and with
the sinuses of the dura, and on the exterior of the skull with the veins of
the pericranium. They are divided into the frontal diploic vein (v. diploica fron-
talis), which opens into the supraorbital vein by an aperture in the supraorbital
notch and into the superior longitudinal sinus; the anterior temporal diploic vein
(v. diploica temporalis anterior), which is confined chiefly to the frontal bone,
communicates with the spheno-parietal sinus and, after escaping by an aperture
in the great wing of the sphenoid, opens into one of the deep temporal veins; the
posterior temporal, or external parietal diploic vein (v. diploica temporalis posterior),
is between the emissarium parietale and the emissarium mastoideum; and the
occipital diploic vein (v. diploica occipitalis) , the largest of the four, which is
confined to the occipital bone, and opens into the emissarium occipitale.
FIG. 450. — Veins of the diploe as displayed by the removal of the outer table of the skull.
The Emissary Veins are considered on page 743.
The Dural or Meningeal Veins (w. meningeae). — They are numerous in the
dura, are without valves, anastomose freely with each other, do not increase in size
as they reach the sinus which receives them, and bear no regular relation to the
dural arteries. The medidural artery has two vena? comites. The other dural
arteries usually have two apiece, but may have but one. The medidural or middle
meningeal veins (w. mediduralis, vv. meningeae mediae) accompany the medidural
artery, are united to the sphenoparietal sinus, pass through the foramen spino-
sum, and join the pterygoid plexus. The other dural veins empty into the longi-
tudinal sinus and communicate with the plexus of the foramen ovale.
The Cerebral Veins (Venae Cerebri).
The cerebral veins are remarkable for the absence of valves and for the extreme
thinness of their coats. The coats are thin because they contain no muscular
tissue. The cerebral veins may be divided into two sets : the superficial veins,
which are placed on the surface, and the deep veins, which occupy the interior of
the organ. The veins of the brain do not accompany associated arteries.
THE CEREBRAL VEINS 735
The Superficial or Cortical Cerebral Veins (venae cerebri externae) ramify upon
the surface of the brain, being lodged in the fissures between the convolutions,
a few running across the convolutions. They receive branches from the sub-
stiiuce of the brain and terminate in the sinuses. They are named, from the
position they occupy, supercerebral or superior, medicerebral or median, and
subcerebral or inferior cerebral veins.
The Supercerebral or Superior Cerebral Veins (vv. superccrebrales, vv. cerebri
superiores], eight to twelve in number on each side, return the blood from the
convolutions on the superior surface of the hemisphere; they pass forward and
inward toward the intercerebral fissure, where they receive the medicerebral
veins; near their termination they become invested with a tubular sheath of the
arachnoid, and open into the longitudinal sinus in the opposite direction to the
course of the current of the blood.
The Medicerebral or Median Cerebral Veins (v. medicerebrales, v. cerebri media)
return the blood from the convolutions of the mesal surface of the corresponding
hemisphere; they open into the supercerebral veins, or occasionally into the falcial
sinus.
The Subcerebral or Inferior Cerebral Veins (vv. subcerebrales, vv. cerebri inferiores)
ramify on the lower part of the outer surface and on the under surface of the cere-
bral hemisphere. Some, collecting tributaries from the under surface of the frontal
lobes of the brain, terminate in the cavernous sinus. One vein of large size, the
medicerebral or superficial sylvian vein, commences on the under surface of the
temporal lobe, and, running along a portion of the sylvian fissure, opens into the
cavernous sinus. The great anastomotic vein of Trolard or the superficial communi-
cating vein establishes a union between the sinuses of the vertex and those of the
base of the brain. It comes from one of the supercerebral veins, passes down-
ward into the sylvian fissure, and, by means of the medicerebral vein, effects a
communication with the cavernous sinus. The posterior anastomotic vein connects
the medicerebral vein with the lateral sinus. Other veins commence on the under
surface of the base of the brain, and unite to form 'from three to five veins, which
open into the superpetrosal and lateral sinuses from before backward.
The Velar, Deep Cerebral, Central, or Ventricular Veins, Veins of Galen (vv.
velares, venae Galeni, vv. cerebri internae) (Fig. 647), are two in number. Each is
formed by the unton of two veins, the vena corporis striati, and the choroid vein, on
either side. The velar veins run backward, parallel with one another, between
the layers of the velum, and in the region of the epiphysis unite to form one
vein, the vena magna Galeni (v. cerebri magna), which passes out of the brain at
the great transverse fissure, between the posterior extremity, or splenium, of the
callosum and the quadrigemina, to enter the tentorial sinus. The two velar veins
receive tributaries from the callosal region, from a portion of the occipital lobe, and
just before their union each vein receives the basilar vein. The vena magna
Galeni receives the vermian vein from the superficial cerebellar veins.
The Vena Corporis Striati on each side commences in the groove between the
corpus striatum and optic thalamus, receives numerous veins from both of these
parts, and unites behind the fornicolumn with the choroid vein to form one of the
velar veins.
The Choroid Vein (v. choroidea) originates in the extreme end of the medi-
cornu of the lateral ventricle and runs along the whole length of the outer border of
the paraplexus, receiving veins from the hippocampus, the fornix, and callosum,
and unites, at the anterior extremity of the paraplexus, with the vein of the corpus
striatum to form the velar vein of that side.
The Basilar Vein (v. basalis) commences at the preperforatum at the base of
the brain by the union of a small precerebral vein, which courses backward
between the frontal lobes of the cerebrum, with the deep sylvian vein, which
736 THE BLOOD-VASCULAR 8Y8TEM
descends through the lower part of the sylvian fissure and receives veins from
the insula. It passes backward over the crus, receiving the inferior striate vein
from the corpus striatum, intercrural veins from the intercrural space, ventricular
veins from the medicornu of the lateral ventricles, and tributaries from the uncinate
gyre, and enters the vein of Galen just before its junction with the vein of the
opposite side. »
The Superficial Cerebellar Veins (Fig. 645) occupy the surface of the cerebellum,
and are disposed in two sets, supercerebellar or superior, and subcerebellar or inferior.
The Supercerebellar or Superior Superficial Cerebellar Veins (w. supercerebellares,
vv. cerebelli superiores] pass partly forward and inward , across the superior vermis
(prevermis) , to terminate in lateral branches which pass partly to the tentorial
sinus and partly outward to the lateral and superpetrosal sinuses.
The Subcerebellar or Inferior Superficial Cerebellar Veins (w. subcerebellares, vv.
cerebelli inferiores) , of large size, terminate in the lateral, subpetrosal, and occipital
sinuses.
The Deep Cerebellar Veins bring blood from the interior of the cerebellum to
the superficial veins.
Veins of the Pons. — Veins come from the depth of the pons, the deep veins,
and empty into a plexus of superficial veins. From this superficial venous plexus
a superior vein passes to the basilar vein, and an inferior vein either into a cerebellar
vein or into the superpetrosal sinus.
Veins of the Oblongata. — Veins pass from the depth of the oblongata and end
in a plexus on the surface. From this plexus comes a ventro-median vein, which
is a prolongation of a like vein of the spinal cord — a dorso-median vein corre-
sponding to a like vein of the cord — and small branches which pass with the roots
of the glosso-pharyngeal, vagus, accessory, and hypoglossal nerves, and empty
into the occipital and the subpetrosal sinuses.
The peri vascular lymph-spaces are especially found in connection with the vessels of the brain.
These vessels are enclosed in a sheath, which acts as a lymphatic channel, through which the
lymph is carried to the subarachnoid and subdural spaces, from which it is returned into the
general circulation.
The Sinuses of the Dura (Sinus Durae Matris) (Figs. 451, 452, 453, 456, 457)
Ophthalmic Veins and Emissary Veins.
The sinuses of the dura are venous channels formed by a separation of the two
layers of this membrane, the outer coat consisting of fibrous tissue, the inner coat
of an endothelial layer continuous with the lining membrane of the veins. The
thick walls of a sinus resist intracranial pressure.1 They are divided into two
sets: (1) those situated at the upper and back part of the skull; (2) those at the
base of the skull. The former are — the
Longitudinal or Superior Longitudinal Sinus. Tentorial or Straight Sinus.
Falcial or Inferior Longitudinal Sinus. Lateral Sinuses.
Occipital Sinus.
The Longitudinal or Superior Longitudinal Sinus (sinus longitudinalis, sinus
sagiUalis superior) (Figs. 451, 452, and 453) occupies the attached margin of the
falx. Commencing at the foramen caecum, through which, in the child, it constantly
communicates by a small branch with the veins of the nasal fossae, it runs from
before backward, grooving the inner surface of the frontal, the adjacent margins
of the two parietal, and the superior division of the crucial ridge of the occipital
bone, and terminates by opening into the torcular. The sinus is triangular on
transverse section, is narrow in front, and gradually increases in size as it passes
backward. On examining its inner surface it presents the internal openings of the
supercerebral veins, which run, for the most part, from behind forward, and open
i A. W. Hughes.
THE SINUSES OF THE DURA
737
chiefly at the back part of the sinus, their orifices being concealed by fibrous
folds; numerous fibrous bands, chordae Willisii (Fig. 453), are also seen extend-
ing transversely across the inferior angle of the sinus; and some small, white,
projecting bodies, the glandulae Pacchioni (granulationes arachnoidales) . This
sinus communicates by numerous small apertures with spaces in the dura
LONGITUDINAL
SINUS
ORIAL
SINUS
FIG. 451. — Coronal section of the skull to show the situations and shapes of the chief sinuses.
(Poirier and Charpy.).
known as lacunae laterales or parasinoidal spaces (Fig. 453). The arachnoid villi
project into these spaces. This sinus receives the supercerebral veins, numerous
veins from the diploe and dura, the outlets of the parasinoidal spaces, and, at the
posterior extremity of the sagittal suture, veins from the pericranium, which pass
through the parietal foramina. In children the longitudinal sinus receives a twig
from the nose which passes through the foramen caecum.
Torcular.
Foramen caecum.
FIG. 452.— Sagittal section of skull, showing the sinuses of the dura.
The Torcular or the Confluence of the Sinuses (Figs. 452 and 456) is the dilated
ctremity of the longitudinal sinus. It is of irregular form, and is lodged on one
47
738
THE BLOOD-VASCULAR SYSTEM
side (generally the right) of the internal occipital protuberance. From it the
lateral sinus of the side to which it is deflected is derived. It receives also the
blood from the occipital sinus.
The Falcial or Inferior Longitudinal Sinus (sinus falcialis, sinus sagittalis
inferior) (Fig. 452), more correctly described as the inferior longitudinal vein, is
contained in the posterior part of the free margin of thefalx. It is of a cylindrical
form, increases in size as it passes backward, and terminates in the tentorial
sinus. It receives several veins from the falx, and occasionally a few from the
mesal surface of the hemispheres.
The Tentorial or Straight Sinus (sinus tentorii, sinus rectus) (Figs. 451 and 452)
is situated at the line of junction of the falx with the tentorium. It is triangular in
form, increases in size as it proceeds backward, and runs obliquely downward and
LONGITUDINAL
SINUS
PARASINOIDAL
SINUS
FIG. 453. — Longitudinal sinus seen from above after removal of the skull-cap. The chordae Willisii are
clearly visible. The parasinoidal sinuses are also well shown. Probes passing from the latter to the longi-
tudinal sinus show that they communicate. (Poirier and Charpy.)
backward from the termination of the falcial sinus to the lateral sinus of the oppo-
site side to that into which the longitudinal sinus is prolonged. It communicates
by a cross-branch with the torcular. Besides the falcial sinus, it receives the vena
magna Galeni and the supercerebellar veins. A few transverse bands cross its
interior. This sinus is usually considered to be formed by the union of the great
vein of Galen and the falcial sinus.
The Lateral Sinus (sinus lateralis, sinus transversus) (Figs. 451, 452, 456, and
457) is of large size. There are two lateral sinuses situated in the attached margin
of the tentorium throughout most of its extent. They commence at the internal
occipital protuberance, one, generally the right, being the direct continuation of the
THE SINUSES OF THE DURA 739
longitudinal sinus, the other of the tentorial sinus. Each passes outward and
forward, describing a slight curve with its convexity upward, to the base of the
petrous portion of the temporal bone, then, leaving the tentorium, curves down-
ward and inward to reach the jugular foramen, where it terminates in the internal
jugular vein. It rests, in its course, upon the inner surface of the occipital, the
posterior inferior angle of the parietal, and the mastoid portion of the temporal
bone, and on the occipital again, at the jugular process, just before its termination.
The portion of the sinus resting on the mastoid process of the temporal and the
jugular process of the occipital bone is not covered by the tentorium and is often
called the sigmoid sinus because of its shape, which resembles the letter S. These
sinuses are frequently of unequal size, that formed by the longitudinal sinus being
the larger, and they increase in size as they proceed from behind forward. The
horizontal portion is of a triangular form, the curved portion semicylindrical.
Their inner surface is smooth, and not crossed by the fibrous bands found in the
other sinuses. The lateral sinuses receive the blood from the superpetrosal sinuses
at the base of the petrous portion of the temporal bone, and they unite with the
subpetrosal sinus, just external to the jugular foramen, to form the internal jugular
vein (Fig. 457). They communicate with the veins of the pericranium by means
of the mastoid and posterior condyloid veins, and they receive some of the subcere-
bral and subcerebellar veins, some veins from the diploe, and often veins from
the internal ear (w. auditivae internae), which come out of the internal auditory
meatus. The petro-squamous sinus, when present, runs backward along the junc-
tion of the petrous and squamous portions of the temporal bone, and opens into the
lateral sinus.
Surgical Anatomy. — The lateral sinus may, as a result of middle-ear disease, be attacked by
suppurative inflammation, which leads to blocking (septic thrombophlebitis). In such a case
the surgeon will be obliged to open the sinus to remove infected clot and tie the internal jugular
vein to intercept thrombi. The line overlying the sinus is as follows: Draw a line horizontally
outward from the occipital protuberance to a point one inch posterior to a vertical line drawn
through the external auditory meatus and from this point drop a second line to the mastoid
process.
The Occipital Sinus (sinus occipitalis) (Fig. 452) is the smallest of the cranial
sinuses. There is often but a single occipital sinus, but occasionally there are
two. It is situated in the attached margin of the falcula. It commences by several
small veins around the margin of the foramen magnum, one of which joins the
termination of the lateral sinus; it communicates with the posterior spinal veins
and terminates in the torcular.
The sinuses at the base of the skull are — the
Cavernous Sinuses. Superpetrosal Sinuses or Superior Petrosal Sinuses.
Sphenoparietal Sinuses. Subpetrosal Sinuses or Inferior Petrosal Sinuses.
Circular Sinus. Transverse Sinus.
The Cavernous Sinus (sinus cavernosus) (Figs. 456 and 457) is named from
presenting a reticulated structure, due to being traversed by numerous interlacing
filaments (Fig. 454). There are two cavernous sinuses, of irregular form, larger
behind than in front, and placed one on each side of the sella turcica, extending
from the sphenoidal fissure to the apex of the petrous portion of the temporal bone.
Each receives anteriorly the ophthalmic vein through the sphenoidal fissure, and
opens behind into the petrosal sinuses. On the inner wall of each sinus is found
the internal carotid artery, accompanied by filaments of the carotid plexus and
by the abducent nerve; and on its outer wall, the oculomotor, trochlear, and
ophthalmic division of the trigeminal nerve (Fig. 454). These parts are separated
740
THE BLOOD-VASCULAR SYSTEM
from the blood flowing along the sinus by the lining membrane, which is continuous
with the inner coat of the veins. The cavernous sinuses receive some of the cerebral
veins, and also the sphenoparietal sinuses. They communicate with the lateral
sinuses by means of the super- and subpetrosal sinuses, and with the facial veins
through the ophthalmic veins. They also communicate with each other by means
of the circular sinus.
CAVERNOUS
TRANSVERSE
SINUS
OCULOMOTOR
NERVE
.TROCHLEAR
NERVE
ABDUCENT
NERVE
OPHTHALMIC
DIVISION OF
TRIGEMINAL NERVE
SUPERIOR MAXIL-
LARY DIVISION OF
TRIGEMINAL NERVE
FIG. 454. — Frontal section through the right cavernous sinus. (Spalteholz.)
Surgical Anatomy.— An arterio-venous communication may be established between the
cavernous sinus and the carotid artery, as it lies in it, giving rise to a pulsating tumor in the
orbit. Such a communication may be the result of injury, such as a bullet wound, a stab, or
a blow or fall sufficiently severe to cause a fracture of the base of the skull in this situation,
or it may occur from the rupture of an aneurism or a diseased condition of the internal
carotid artery. The disease begins with sudden noise and pain in the head, followed by
exophthalmos, swelling and "congestion of the lids and conjunctive. A pulsating tumor
develops at the margin of the orbit, with thrill and the characteristic bruit; accompanying
these symptoms there may be impairment of sight, paralysis of the iris and orbital muscles,
and pain of varying intensity. In some cases the opposite orbit becomes affected by the passage
of the arterial blood into the opposite sinus by means of the circular sinus. Or the arterial
blood may find its way through the emissary veins into the pterygoid plexus, and thence into the
veins of the face. Pulsating tumors of the orbit may also be due to traumatic aneurism of
one of the orbital arteries, and symptoms resembling those of pulsating tumor may be produced
by pressure on the ophthalmic vein, as it enters the sinus, by an aneurism of the internal
carotid artery.
The Sphenoparietal Sinus or Sinus Alae Parvae (sinus sphenoparietalis}.—
Each of these sinuses is lodged in the dura on the under surface of the lesser wing of
the sphenoid bone. It takes origin from one of the medidural veins, usually
receives blood from the diploe of the skull, passes inward, and ends in the anterior
part of the cavernous sinus.
The Ophthalmic Veins are two in number, superior and inferior.
The superior ophthalmic vein (v. ophthalmica superior} (Fig. 455) begins as the
naso-frontal vein (v. nasofrontalis) , at the inner angle of the orbit, which communi-
cates with the angular vein. It joins the angular vein with the cavernous sinus;
it pursues the same course as the ophthalmic artery, and receives tributaries corre-
sponding to the branches derived from that vessel. Forming a short single trunk,
it passes through the inner extremity of the sphenoidal fissure, and terminates in
the cavernous sinus. It anastomoses with the inferior ophthalmic vein and receives
lachrymal, anterior, and posterior ethmoidal and muscular branches, and veins
of the eyelids and of the bulbus oculi.
THE SINUSES OF THE DURA
741
The inferior ophthalmic vein (v. ophthalmica inferior) (Fig. 455) arises in the veins
of the eyelids and lachrymal sac, receives the veins from the floor of the orbit, and
CAVERNOUS.
SINUS
INFERIOR
OPHTHALMIC
FIG. 455 — Veins of the orbit. (Poirier and Charpy.)
from the portion of the nasal fossa supplied by the anterior and posterior ethmoidal
arteries. It either passes out of the orbit through the spheno-m axillary fissure to
join the pterygoid plexus of veins, or else, passing backward through the sphenoidal
Opening of mastoid
vein.
- Torculur
FIG. 456. — The sinuses at the base of the skull.
fissure, it enters the cavernous sinus, either by a separate opening, or, more fre-
quently, in common with the superior ophthalmic vein. It receives muscular
742
THE BLOOD- VASCULAR SYSTEM
tributaries and veins of the bulbus oculi, and anastomoses with the superior
ophthalmic vein.
The Circular Sinus (sinus circularis) (Figs. 454 and 456) is formed by two trans-
verse vessels, the anterior and posterior intercavernous sinuses (sinus intercavernous
anterior and sinus intercavernous posterior), which connect together the two
cavernous sinuses; the one passing in front and the other behind the hypophysis,
and thus forming with the cavernous sinuses a venous circle around that body.
The anterior one is usually the larger of the two, and one or other is occasionally
found to be absent.
Falx
Optic nerve
Int. carotid artery
Oculomotor nerve
— Dorsum sellse
Glosso-pharyngeal,
vagus, and acces-
sory nerves
Lateral sinus
FIG. 457. — Relation of nerves to sinuses in jugular foramen. (Henle.)
The Superpetrosal or Superior Petrosal Sinus (sinus super petrosus, sinus petro-
sus superior) (Figs. 452 and 456) is situated along the superior border of the petrous
portion of the temporal bone, in the front part of the attached margin of the
tentorium. It is small and narrow, and connects together the cavernous and
lateral sinuses at each side. It receives some cerebellar and subcerebral veins, and
usually veins from the tympanic cavity.
The Subpetrosal or Inferior Petrosal Sinus (sinus subpetrosus, sinus petrosus
inferior) (Figs. 452 and 456) is situated in the groove formed by the junction of the
posterior border of the petrous portion of the temporal with the basilar process of
the occipital bone. It commences in front at the termination of the cavernous
sinus, and behind joins the lateral sinus after it has passed through the jugular
foramen; the junction of these two sinuses forming the commencement of the
internal jugular vein. The subpetrosal sinus receives a vein from the internal
ear and also veins from the medulla, pons, and under surface of the cerebellum.
The junction of the two sinuses takes place at the lower border of, or just external
to, the jugular foramen. The exact relation of the parts to one another in the
THE SINUSES OF THE DURA 743
foramen is as follows: The subpetrosal sinus is in front, with the dural branch of
the ascending pharyngeal artery, and is directed obliquely downward and back-
ward; the lateral sinus is situated at the back part of the foramen with a dural
branch of the occipital artery, and between the two are the glosso-pharyngeal,
vagus, and accessory nerves (Fig. 457). These three sets of structures are divided
from each other by two processes of fibrous tissue. The junction of the sinuses
takes place superficial to the nerves, so that these latter lie a little internal to the
venous channels in the foramen (Fig. 457). These sinuses are semicylindrical
in form.
The Transverse or Basilar Sinus (plexus basilaris} (Figs. 456 and 457) con-
sists of several interlacing veins between the layers of the dura over the basilar
process of the occipital bone, which serve to connect the two subpetrosal sinuses.
With them the anterior spinal veins communicate.
Emissary Veins (emissaria). — The emissary veins are vessels which pass
through apertures in the cranial wall and establish communications between the
sinuses inside the skull and the diploic veins in the diploe, and the veins external
to the skull. Some of these are always present, others only occasionally so.
They vary much in size in different individuals. The principal emissary veins
are the following: 1. A vein, almost always present, which passes through the
mastoid foramen (emissarium mastoideum} and connects the lateral sinus with
the posterior auricular or with an occipital vein. 2. A constant vein which
passes through the parietal foramen (emissarium parietale) and connects the
longitudinal sinus with the veins of the scalp. 3. A plexus of minute veins which
pass through the anterior condyloid foramen (emissarium condyloideum) and
connect the occipital sinus with the vertebral vein and deep veins of the neck.
4. An inconstant vein which passes through the posterior condyloid foramen and
connects the lateral sinus with the deep veins of the neck. 5. One or two veins
of considerable size which pass through the foramen ovale and connect the cav-
ernous sinus with the pterygoid and pharyngeal plexuses. 6. Two or three small
veins which pass through the foramen lacerum medium and connect the cavernous
sinus with the pterygoid and pharyngeal plexuses. 7. There is sometimes a small
vein connecting the same parts and passing through the inconstant foramen of
Vesalius at the root of the pterygoid process of the sphenoid bone. 8. A plexus of
veins passing through the carotid canal and connecting the cavernous sinus with
the internal jugular vein. 9. A small vein (emissarivm occipitale) usually con-
nects the occipital vein with the lateral sinus or the torcular and the occipital
diploic vein.
Surgical Anatomy. — These emissary veins are of great importance in surgery. In addition
to them there are, however, other communications between the intra- and extra-cranial circula-
tion, as, for instance, the communication of the angular and supra-orbital veins with the ophthal-
mic vein at the inner angle of the orbit, and the communication of the veins of the scalp with
the diploic veins. Through these communications inflammatory processes commencing on the
outside of the skull may travel inward, leading to osteo-phlebitis of the diploe and inflammation
of the membranes of the brain. To this in former days was to be attributed one of the principal
dangers of scalp wounds and other injuries of the scalp.
By means of these emissary veins blood may be abstracted almost directly from the intra-
cranial circulation. For instance, leeches applied behind the ear abstract blood almost directly
from the lateral sinus by means of the vein passing through the mastoid foramen. Again,
epistaxis in children will frequently relieve severe headache, the blood which flows from the nose
being derived from the longitudinal sinus by means of the vein which passes through the foramen
caecum, which is another communication between the intracranial and extracranial circulation
constantly found in children.
744
THE BLOOD -VASCULAR SYSTEM
VEINS OF THE UPPER EXTREMITY AND THORAX.
The veins of the Upper Extremity are divided into two sets, superficial and
deep.
The Superficial Veins are placed immediately beneath the integument between
the layers of superficial fascia.
POSTERIOR
ULNAR'
SUPERFICIAL
RADIAL
DORSAL
VENOUS ARCH
FIG. 458.— The veins on the dorsum of the hand. (Bourgery.)
The Deep Veins accompany the arteries, and constitute the venae comites of
those vessels.
Both sets of vessels are provided with valves, which are more numerous in the
deep than in the superficial veins.
THE SUPERFICIAL VEINS OF THE UPPER EXTREMITY 745
The Superficial Veins of the Upper Extremity (Fig. 459).
The superficial veins of the upper extremity are — the
Superficial Veins of the Hand. Median.
Anterior Ulnar. Median Cephalic.
Posterior Ulnar. Median Basilic.
Common Ulnar. Basilic.
Radial. Cephalic.
The Superficial Veins of the Hand and Fingers (Figs. 458 and 459) are
principally situated on the dorsal surface. These dorsal veins begin in each finger
as a venous plexus, in which are distinct veins running in a longitudinal direction,
and called dorsal digital veins (w. digitales dorsales propriae) . The dorsal digital
veins terminate over the first phalanges, in the venous arches of the fingers (arcus
venosi digitales}. From these arches take origin the four dorsal interosseous or
the interdigital veins (vv. metacarpeae dorsales). These veins form the dorsal venous
plexus of the hand (rete venosum dor sale manus). This plexus lies in a line with the
lower ends of the shafts of the metacarpal bones. It receives the dorsal inter-
osseous veins, the radial digital vein of the index finger, and numerous superficial
veins from the back of the hand. It gives origin to the superficial radial vein and
the posterior ulnar vein. The superficial veins of the palmar surface are of less
diameter than the dorsal veins. They arise from each of the phalanges by a
plexus (vv. digitales volares propriae). Vessels at the edges of the fingers take most
of the blood to the dorsal veins. There are also veins in the finger webs (w. inter-
capitulares) , which take blood from the palm to the dorsum. A superficial plexus,
the palmar plexus, lies upon the palmar fascia, the fascia of the thenar eminence,
and the fascia of the hypo thenar eminence.
The Anterior Ulnar Vein (v. ulnaris anterior) (Fig. 459) commences on the
anterior surface of the ulnar side of the hand and wrist, and ascends along the
anterior surface of the ulnar side of the forearm to the bend of the elbow, where
it joins with the posterior ulnar vein to form the common ulnar. Occasionally it
opens separately into the median basilic vein. It communicates with branches
of the median vein in front and with the posterior ulnar behind.
The Posterior or Dorsal Ulnar Vein (v. ulnaris posterior) (Fig. 458) commences
on the posterior surface of the ulnar side of the wrist. It runs on the posterior
surface of the ulnar side of the forearm, and just below the elbow unites with
the anterior ulnar vein to form the common ulnar, or else joins the median
basilic and helps to form the basilic. It communicates with the deep veins
of the palm by a branch which emerges from beneath the Abductor minimi digiti
muscle.
The Common Ulnar Vein (v. ulnaris communis) (Fig. 459) is a short trunk
which is not constant. When it exists it is formed by the junction of the two
preceding veins, and, passing upward and outward, joins the median basilic to
form the basilic vein. When it does not exist the anterior and posterior ulnar
veins open separately into the median basilic vein.
The Radial Vein '(v. radialis) (Figs. 459 and 460) commences upon the dorsal
surface of the wrist, communicating with the deep veins of the palm by a branch
which passes through the first interosseous space. The radial vein soon forms a
large vessel, which ascends along the radial side of the forearm and receives
numerous veins from both its surfaces. At the bend of the elbow it unites with
the median cephalic to form the cephalic vein. Spalteholz considers the ulnar
vein as a portion of the basilic and the radial vein a portion of the cephalic.
The Median Vein (v. mediana cubiti) (Fig. 459) ascends on the front of the
forearm, and communicates with the anterior ulnar and radial veins. At the bend
746
THE BLOOD -VASCULAR SYSTEM
Median cephalic.
External
cutaneous nerve.
FIG. 459. — The superficial veins of the flexor aspect
of the upper extremity.
of the elbow it receives a branch of
communication from the deep veins,
the deep median vein, and divides into
two branches, the median cephalic and
median basilic, which diverge from each
other as they ascend.
The Median Cephalic (v. mediana
cephalica)(F'ig. 459), usually the smaller
of the two, passes outward in the groove
between the Supinator longus and Bi-
ceps muscles, and joins with the radial
to form the cephalic vein. The branches
of the external cutaneous nerve pass
beneath this vessel.
The Median Basilic Vein (v. mediana
basilica) (Fig. 459) passes obliquely in-
ward, in the groove between the Biceps
and Pronator radii teres muscles, and
joins the common ulnar to form the
basilic. This vein passes in front of
the brachial artery, from which it is
separated by a fibrous expansion, the
bicipital fascia, which is given off from
the tendon of the Biceps to the fascia
covering the Flexor muscles of the fore-
arm. Filaments of the internal cuta-
neous nerve pass in front as well as
behind this vessel.1
Venesection is usually performed at the
bend of the elbow, and as a matter of practice
the largest vein in this situation is commonly
selected. This is usually the median basilic,
and there are anatomical advantages and dis-
advantages in selecting this vein. The advan-
tages are, that in addition to its being the
largest, and therefore yielding a greater supply
of blood, it is the least movable and can be
easily steadied on the bicipital fascia on which
it rests. The disadvantages are, that it is in
close relationship with the brachial artery,
separated only by the bicipital fascia; and
formerly, when venesection was frequently
practised, arterio- venous aneurism was no
uncommon result of this practice. Another
disadvantage is. that the median basilic is
crossed by some of the branches of the internal
cutaneous nerve, and these may be divided
in the operation, giving rise to " traumatic
neuralgia of extreme intensity" (Tillaux).
The Basilic Vein (v. basilica) (Figs.
460 and 462) is of considerable size and
is formed by the coalescence of the
common ulnar vein with the median
1 Cruveilhier says: "Numerous varieties are observed in the disposition of the veins of the elbow; some-
times the common median vein is wanting; but in those cases its two branches are furnished by the radial vein,
and the cephalic is almost always in a rudimentary condition. In other cases only two veins are found at the
bend of the elbow, the radial and ulnar, which are continuous, without any demarcation, with the cephalic and
basilic." — ED. of 15th English edition.
THE DEEP VEINS OF THE UPPER EXTREMITY 747
basilic. It passes upward along the inner side of the Biceps muscle and pierces
the deep fascia a little below the middle of the arm. The opening in the fascia
is known as the semilunar hiatus (hiatus semilunaris) . The vein ascends in the
course of the brachial artery to the lower border of the tendons of the Latissimus
dorsi and Teres major muscles, and is continued onward as the axillary vein.
The Cephalic Vein (v. cephalica) (Fig. 459) is formed by the union of the
median cephalic and the radial veins. It courses along the outer border of the
Biceps muscle, lying in the same groove with the upper external cutaneous branch
of the musculo-spiral nerve, to the upper third of the arm; it then passes in the
interval between the Pectoralis major and Deltoid muscles, lying in the same
groove with the descending or humeral branch of the acromial-thoracic artery.
It pierces the costo-coracoid membrane, and, crossing the axillary artery, ter-
minates in the axillary vein just below the clavicle. This vein is occasionally
connected with the external jugular or subclavian by a branch which passes
from it upward in front of the clavicle.
The Deep Veins of the Upper Extremity (Fig. 460).
The deep veins of the upper extremity follow the course of the arteries, forming
their venae comites or companion veins. Usually there is one vein lying on each
side of the corresponding artery, and they are connected at intervals by short
transverse branches.
There are two digital veins accompanying each artery along the sides of the
fingers: these, uniting at their base, pass along the interosseous spaces in the
palm, and terminate in the two venae comites which accompany the superficial
palmar arch. Branches from these vessels on the radial side of the hand accom-
pany the superficialis volae, and on the ulnar side terminate in the deep ulnar
veins (Fig. 460). The deep ulnar veins, as they pass in front of the wrist, com-
municate with the interosseous and superficial veins, and at the elbow unite with
the deep radial veins to form the venae comites of the brachial artery. The vense
comites of the brachial communicate by numerous transverse branches, which
cross over or under the artery.
The Interosseous Veins (Fig. 460) accompany the anterior and posterior
interosseous arteries. The anterior interosseous veins commence in front of the
wrist, where they communicate with the deep radial and ulnar veins; at the upper
part of the forearm they receive the posterior interosseous veins, and terminate in
the venae comites of the ulnar artery.
The Deep Palmar Veins accompany the deep palmar arch, being formed by
tributaries which accompany the ramifications of that vessel. At«the wrist they
receive a dorsal and a palmar tributary from the thumb. The deep palmar veins
communicate with the deep ulnar veins at the inner side of the hand, and on the
outer side terminate in the deep radial veins (Fig. 460), which are the venae
comites of the radial artery. Accompanying the radial artery the deep radial
veins terminate in the venae comites of the brachial artery.
The Brachial Veins (vv. brachiales) (Fig. 460) are placed one on each side of
the brachial artery, receiving tributaries corresponding with the branches given off
from that vessel; at the lower margin of the Subscapularis muscle they join the
axillary vein.
These deep veins have numerous anastomoses, not only with each other, but
also with the superficial veins. 'One of the brachial veins empties into the
axillary, the other, usually the smaller, generally unites with the basilic.
The Axillary Vein (v. axillaris) (Fig. 461) is of large she, and may be regarded
as the continuation upward of the basilic vein, or as formed by the fusion of a
brachial vein with the basilic vein. If the first view is accepted a. brachial vein
is described as one of the tributaries of the axillary vein. The axillary vein com-
748
THE BLOOD-VASCULAR SYSTEM
mences at the lower border of the tendons of the Teres major and Latissimus dorsi
muscles, increases in size as it ascends, by receiving tributaries corresponding with
the branches of the axillary artery, and terminates immediately beneath the clavicle
at the outer border of the first rib, where it becomes the subclavian vein. This
vessel is covered in front by the Pectoral muscles and costocoracoid membrane,
and lies on the thoracic side of the axillary artery, which it partially overlaps. It
receives the brachial veins, the venae comites of the axillary artery except the cir-
cumflex veins; and near its termination the cephalic vein. This vein is provided
with a pair of valves opposite the lower border of the Subscapularis muscle; valves
are also found at the termination of the cephalic and subscapular veins. The
circumflex veins end in the subscapular or one of the brachial veins.
The Long Thoracic Branch (v. thoracalis lateralis) (Fig. 462) receives the thoracico-
epigastric vein (v. thoracoepigastrica), which comes all the way from the superficial
epigastric or from the femoral vein.
The Costo-axillary Veins (w. costoaxillares) (Fig. 462) come from the first six
intercostal spaces and bring blood from the intercostal veins to the axillary.
INTEROSSEOUS
VEINS
ULNAR DEEP
VEINS
VENJE COMITES
'OF BRACHIAL
AR/TERV
ANASTOMOSIS
OF RADIAL
AND ULNAR
RADIAL DEEP
VEINS
FIG. 460. — The deep veins of the upper extremity. (Bourgery.)
Surgical Anatomy. — There are several points of surgical interest in connection with the
axillary vein. Being more superficial, larger, and slightly overlapping the axillary artery, it is
more liable to be wounded in the operation of extirpation of the axillary glands, especially as
these glands, when diseased, are apt to become adherent to the vessel. When wounded there
is always danger of air being drawn into its interior, and death resulting. This is due not only
to the fact that it is near the thorax, and therefore liable to be influenced by the respiratory
movements, but also because it is adherent by its anterior surface to the costo-coracoid membrane,
and therefore if wounded is likely to remain patulous and favor the chance of air being sucked
in. This adhesion of the vein to the fascia prevents its collapsing, and therefore favors the
furious bleeding which takes place in these cases.
THE DEEP VEINS OF THE UPPER EXTREMITY
749
To avoid wounding the axillary vein in the extirpation of glands from the axilla no undue
force should be used in isolating the glands. If the vein is found to be so embedded in the
malignant deposit that the latter cannot be removed without taking away a part of the vein,
this must be done, the vessel having been first ligated above and below.
AXILLARY
ARTERY
MUSCULO-
CUTANEUS NERVC
-AXILLARY
PECTORALIS
MAJOR
MUSCLE
SUBCLAVIUS
MUSCLE
COSTO-AXILLARY
LONG THORACIC
FIG. 461.— The veins of the right axilla, viewed from in front. (Spalteholz.)
• The Subclavian Vein (v. subclavia) (Figs. 424 and 446), the continuation of the
axillary, extends from the outer border of the first rib to the inner end of the clavicle,
where it unites with the internal jugular to form the innominate vein. It is in
relation, in front, with the clavicle and Subclavius muscle; behind and above, with
the subclavian artery, from which it
is separated internally by the Scal-
enus anticus muscle and phrenic
nerve. Below, it rests in a depres-
sion on the first rib and upon the
pleura. Above, it is covered by the
cervical fascia and integument.
An expansion of the aponeurosis
of the Subclavius muscle lies upon
the vein (Fig. 462).
The subclavian vein occasionally
rises in the neck to a level with the
third part of the subclavian artery, and in two instances has been seen passing
with this vessel behind the Scalenus anticus. This vessel is usually provided
with valves about an inch from its termination in the innominate, just external
to the entrance of the external jugular vein.
Tributaries. — It receives the external and anterior jugular veins and a small
branch from the cephalic, outside the Scalenus, and on the inner side of that
muscle the internal jugular vein. At the angle of junction with the internal
The aponeurotic expansion of the Subclavius
(Poirier and Charpy.)
FIG. 462
muscle over the subclavian vein.
750
THE BLOOD- VASCULAR SYSTEM
jugular the left subclavian vein receives the thoracic duct (Fig. 463), while the
right subclavian vein receives the right lymphatic duct.
The Innominate or Brachio-cephalic Veins (w. anonymae] (Fig. 464) are
two large trunks, placed one on each side of the root of the neck, and formed by
the union of the internal jugular and subclavian veins of the corresponding side.
The Right Innominate Vein (v. anonyma dextra) is a short vessel, an inch
in length, which commences at the inner end of the clavicle, and, passing almost
vertically downward, joins with the left innominate vein just below the cartilage
of the first rib, close to the right border of the sternum, to form the precava, or
superior vena cava. It lies superficial and external to the innominate artery; on its
right side is the phrenic nerve, and the pleura is here interposed between it and the
apex of the lung. This vein, at the angle of junction of the internal jugular with
the subclavian, receives the right vertebral vein, and, lower down, the right internal
mammary, right inferior thyroid, and sometimes the right thyroid ea ima and the
right superior intercostal veins.
The Left Innominate Vein (v. anonyma sinistra), about two and a half inches
in length, and larger than the right, passes from left to right across the upper and
front part of the chest, at the same time inclining downward, and unites with
LONGUS COLLI MUSCLE
COMMON CAROTID
ARTERY
LEFT VAGUS
NERVE
VERTEBRAL ARTERY
VERTEBRAL VEIN
THORACIC DUCT
INTERNAL JUGULAR
VEIN
EXTERNAL JUGULAR
VEIN
ANTERIOR JUGULAR
VEIN
SUBCLAVIAN
VEIN
FIG. 463. — The bend of the thoracic duct at its termination in the subclavian vein. (Poirier and Charpy.)
the right innominate vein to form the precava. It is in relation, in front, with the
first piece of the sternum, from which it is separated by the Sterno-hyoid and
Sterno-thyroid muscles, the thymus gland or its remains, and some loose areolar
tissue. Behind, it lies across the roots of the three large arteries arising from the
arch of the aorta. This vessel is joined by the left vertebral, left internal mammary,
left inferior thyroid, left thyroid ea ima, and the left superior intercostal veins, and
occasionally some thymic and pericardiac veins, and the right thyroidea ima.
There are no valves in the innominate veins.
Peculiarities. — Sometimes the innominate veins open separately into the right auricle; in
such cases the right vein takes the ordinary course of the precava; but the left vein — the left
precava, or left superior vena cava, as it is termed — after communicating by a small branch with
the right one, passes in front of the root of the left lung, and, turning to the back of the heart,
receives the cardiac veins, and terminates in the back of the right auricle. This occasional
condition in the adult is due to the persistence of the early foetal condition, and is the normal
state of things in birds and some mammalia.
The Internal Mammary Vein (v. mammaria internet) corresponds to the internal
mammary artery, follows the course of that vessel, and receives branches corre-
sponding with those derived from it. There are two internal mammary veins in the
region of the Triangularis sterni muscle, but above this point the vein is single. The
double vein is formed by the union of the vense comites of the superior epigastric
THE DEEP VEINS OF THE UPPER EXTREMITY
751
..Anterior jugular.
Superior thyroid.
External jugular.
Mediastinal
and
pericardiac.
artery (vv. epigastricae superiores) and the venae comites of the musculo-phrenic
artery (vv.musculophrenicae). It receives the twelve anterior intercostal veins from
the upper six intercostal spaces of the corresponding side — six anterior perforating
veins (rami perforantes) —
veins from the surface of the
sternum (rami sternales) —
muscular veins, and vessels
from the mediastinum and
pleura. The two veins of Middle thyroid. A
each side unite into a single
trunk, at the upper margin
of the triangularis sterni
muscle, which terminates in
the innominate vein.
The Vertebral Vein (see
p. 732).
Thelnf erior Thyroid Veins
(vv. thyreoideae inferiores)
(Fig. 464), two, frequently
three or four, in number,
arise in the venous plexus
on the thyroid body (plexus
thyreoideus impar), commu-
nicating with the middle
and superior thyroid veins.
(See Kocher's views, pages
731 and 732.) Kocher states
that two thyroidea ima veins
are present, and that inferior
thyroid veins may also be
present. The veins from the
lower portion of the gland
form a plexus in front of the
trachea, behind the Sterno-
thyroid muscles. From this
plexus a left vein descends
and joins the left innomi-
nate trunk, and a right vein
passes obliquely downward
and outward across the in-
nominate artery to open into
the right innominate vein,
just at its junction with the
precava. The thyroidea ima
vein (v. thyreoidea ima)
passes downward in front of
the trachea and terminates
in the left innominate vein.
These veins receive tribu-
taries from the tracheal veins
(vv. tracheales), from the
ffisophageal veins (vv. oesopha-
geae), from the inferior laryn-
Vein(l? lartinoea inferior] ^IG' ^4' — ^^ venae cavse and azygos veins, with their formative
y u J / branches.
752
THE BLOOD -VASCULAR SYSTEM
The Intercostal Veins (vv. intercostales) are divided into anterior and posterior
intercostals.
The Anterior Intercostal Veins are tributaries of the internal mammary or the
musculo-phrenic veins (p. 750).
The Posterior Intercostal Veins (Fig. 464) number eleven on each side, there
being one vein in each intercostal space. Each vein lies in the groove at the
lower margin of the rib above the corresponding intercostal artery. On the right
side the first posterior intercostal vein crosses the neck of the first rib anteriorly
and opens into the vertebral vein or the innominate vein. The first posterior
intercostal of the left side follows a like course, and empties into the vertebral
or innominate vein. The posterior intercostals of the right side, from the fifth
to the eleventh, inclusive, open individually into the vena azygos major. The
left upper azygos vein receives the fifth, sixth, seventh, and eighth posterior
intercostals of the left side. The left lower azygos vein receives the ninth, tenth,
and eleventh left posterior intercostals.
The Right Superior Intercostal Vein (v. intercostalis suprema dextra) is formed
by the union of the second, third, and fourth right posterior intercostals. It
passes downward and inward and opens into the vena azygos major.
The Left Superior Intercostal Vein (v. intercostalis suprema sinister) runs across
the transverse aorta and opens into the left innominate vein. It usually receives
the left bronchial and left superior phrenic vein, and communicates below with
the vena azygos minor superior. Each posterior intercostal vein obtains branches
from the ribs and muscles and also a dorsal branch, which receives blood from the
muscles of the back, from in front of the vertebral bodies, from back of the ver-
tebral arches, and from the spinal canal by way of a vein which passes through
the intervertebral foramen.
The Precava or Superior Vena Cava (v. cava superior) (Fig. 464) receives the
blood which is conveyed to the heart from the whole of the upper half of the body.
It is a short trunk, varying from two inches and a half to three inches in length,
formed by the junction of the two innominate veins. It commences immediately
below the cartilage of the first rib close to the sternum on the right side, and,
descending vertically, enters the pericardium about an inch arid a half above the
heart, and terminates in the upper part of the right auricle opposite the upper
border of the third right costal cartilage. In its course it describes a slight curve,
the convexity of which is turned to the right side.
Relations. — In front, with the pericardium and process of cervical fascia which
is continuous with it: this separates it from the thymus gland and from the ster-
num; behind, with the root of the right lung; on its right side, with the phrenic
nerve and right pleura ; on its left side, with the commencement of the innominate
artery and ascending part of the aorta. The portion contained within the peri-
cardium is covered by the serous layer of that membrane in its anterior three-
fourths. It receives the vena azygos major just before it enters the pericardium,
and several small veins from the pericardium and parts in the mediastinum. The
precava has no valves.
The Azygos Veins connect together the precava and postcava, taking the
place of those vessels in that part of the chest occupied by the heart.
The Larger or Right Azygos Vein or the Vena Azygos Major (v. azygos) (Fig. 464)
commences opposite the first or second lumbar vertebra by a branch from the right
lumbar veins, called the right ascending lumbar vein (v. lumbalis ascendens dextra) ;
sometimes by a branch from the right renal vein or from the postcava. It enters
the thorax through the aortic opening in the Diaphragm, and passes along the
right side of the vertebral column to the fourth thoracic vertebra, where it arches
forward over the root of the right lung, and terminates in the precava just before
that vessel enters the pericardium. Whilst passing through the aortic opening
THE SPINAL VEINS 753
of the Diaphragm it lies with the thoracic duct on the right side of the aorta,
and in the thorax it lies upon the intercostal arteries on the right side of the aorta
and thoracic duct, and is partly covered by pleura.
Tributaries. — It receives the lower ten posterior intercostal veins of the right side,
the upper two or three of these opening, first of all, into the right superior inter-
costal vein. It receives the azygos minor veins, several oesophageal, mediastinal,
and pericardial veins; near its termination, the right bronchial vein; and generally
the right superior intercostal vein. A few imperfect valves are found in this vein;
but its tributaries are provided with complete valves.
The intercostal veins on the left side, below the three upper intercostal spaces,
usually form two trunks, named the left lower and the left upper azygos veins.
The Left Lower or Smaller Azygos Vein or the Vena Azygos Minor (v. hemiazygos}
(Fig. 464) commences in the lumbar region by a branch from one of the lumbar
veins, ascending lumbar (v. lumbalis ascendens), or from the left renal. It passes
into the thorax through the left crus of the Diaphragm, and, ascending on the
left side of the spine as high as the ninth thoracic vertebra, passes across the
column, behind the aorta and thoracic duct, to terminate in the right azygos vein.
It receives the four or five lower intercostal veins of the left side, and some
oesophageal and mediastinal veins.
The Left Upper Azygos Vein (v. hemiazygos accessorial) varies inversely with the
size of the left superior intercostal. It receives veins from the intercostal spaces
between the left superior intercostal vein and highest tributary of the left lower
azygos. They are usually three or four in number, usually the fourth, fifth, sixth,
and seventh left posterior intercostal veins. They join to form a trunk which ends
in the right azygos vein or in the left lower azygos. It sometimes receives the left
bronchial vein. When this vein is small or altogether wanting, the left superior
intercostal vein will extend as low as the fifth or sixth intercostal space.
Surgical Anatomy.— In obstruction of the postcava the azygos veins are one of the prin-
cipal means by which the venous circulation is carried on, connecting as they do the precava
and postcava, and communicating with the common iliac veins by the ascending lumbar veins,
and with many of the tributaries of the postcava.
The Bronchial Veins (vv. bronchioles) return the blood from the substance of
the lungs, except from the smaller bronchial tubes and alveola. The blood from
them is received by the pulmonary veins. The bronchial vein of the right side
opens into the vena azygos major near its termination. The bronchial vein of
the left side opens into the left superior intercostal vein or the left upper azygos
vein. The bronchial veins are joined by veins from the trachea and medias-
tinum.
The Spinal Veins.
The numerous venous plexuses placed upon and within the spine may be
arranged into four sets:
1. Those placed on the exterior of the spinal column, the dorsi-spinal veins.
2. Those situated in the interior of the spinal canal, between the vertebrae and
the theca vertebralis, meningo-rachidian veins.
3. The veins of the bodies of the vertebra*, venae basis vertebrarum.
4. The veins of the spinal cord, medulli-spinal veins.
1. The Dorsi-spinal Veins (plexus venosi vertebrates externi) commence by
small branches which receive their blood from the integument of the back of the
spine and from the muscles in the vertebral grooves. They constitute two plexuses :
an anterior plexus (plexus venosi vertebrates anteriores) upon the vertebral bodies
and a posterior plexus (plexus venosi vertebrates posteriores) , which surrounds the
spinous processes, the laminae, and the transverse and articular processes of
48
754
THE BLOOD -VASCULAR SYSTEM
all the vertebrae. At the bases of the transverse processes they communicate, by
means of ascending and descending branches, with the veins surrounding the
contiguous vertebrae, and they join with the veins in the spinal canal by branches
which perforate the ligamenta subflava. Other branches pass obliquely forward,
between the transverse processes, and communicate with the intraspinal veins
through the intervertebral foramina (w. intervertebrales). The dorsi-spinal veins
terminate by joining the vertebral veins in the neck, the intercostal veins in the
thorax, and the lumbar and sacral veins in the loins and pelvis.
The dorsi-spinal veins.
FIG. 465. — Transverse section of a thoracic vertebra, showing the spinal veins.
2. The Meningo-rachidian Veins (plexus venosi vertebrates interni). — The
principal veins contained in the spinal canal are situated between the theca verte-
bralis and the vertebrae. They consist of two longitudinal plexuses, one of which
runs along the posterior surface of the bodies of the vertebrae, anterior longitudinal
spinal veins. The other plexus, posterior longitudinal spinal veins, is placed on the
inner or anterior surface of the laminae of the vertebrae.
FIG. 466. — Vertical section of two thoracic vertebra?, showing the spinal veins.
The Anterior Longitudinal Spinal Veins (sinus vertebrales longitudinales] consist
of two large, tortuous veins which extend along the whole length of the vertebral
column, from the foramen magnum, where they communicate by a venous ring
around that opening, to the base of the coccyx, being placed one on each side of
the posterior surface of the bodies of the vertebrae along the margin of the posterior
common ligament. These veins communicate together opposite each vertebra by
VEIN8 OF LOWER EXTREMITY, ABDOMEN AND PELVIS 755
transverse trunks which pass beneath the ligament. Each transverse trunk
receives the large vena basis vertebrae (v. basivertebralis) from the interior of the
body of the vertebra. The anterior longitudinal spinal veins are least developed
in the cervical and sacral regions. They are not of uniform size throughout,
being alternately enlarged and constricted. At the intervertebral foramina they
communicate with the dorsi-spinal veins, and with the vertebral veins in the neck,
with the intercostal veins in the thoracic region, and with the lumbar and sacral
veins in the corresponding regions.
The Posterior Longitudinal Spinal Veins, smaller than the anterior, are situated
one on each side, between the inner surface of the laminae and the theca verte-
bralis. They communicate (like the anterior) opposite each vertebra by trans-
verse trunks, and with the anterior longitudinal veins by lateral transverse branches
which pass from behind forward. The posterior longitudinal veins, by branches
which perforate the ligamenta subflava, join with the dorsi-spinal veins. From
them branches are given off which pass through the intervertebral foramina and
join the vertebral, intercostal, lumbar, and sacral veins. The anterior and pos-
terior longitudinal spinal veins join by numerous branches and really constitute
one plexus, the plexus venosi vertebrales interni.
The Intervertebral Veins (w. intervertebrales) accompany the spinal nerves
in the intervertebral foramina, receive veins from the spinal cord, and join the
meningo-rachidian and the dorsi-spinal veins.
3. The Veins of the Bodies of the Vertebrae or the Venae Basis Vertebrarum
(w. basivertebrales) emerge from the foramen on the posterior surface of each
vertebra and join the transverse trunk connecting the anterior longitudinal spinal
veins. They are contained in large, tortuous channels in the substance of the
bones, similar in every respect to those found in the diploe of the cranial bones.
These canals lie parallel to the upper and lower surface of the bones. They com-
mence by small openings on the front and sides of the bodies of the vertebrae,
through which communicating branches from the veins external to the bone pass
into its substance, and converge to the principal canal, which is sometimes double
toward its posterior part. They open into the corresponding transverse branch unit-
ing the anterior longitudinal veins. They become greatly developed in advanced age.
4. The Veins of the Spinal Cord or the Medulli-spinal Veins (w. spinales]
emerge from the cord substance and enter the pia plexus. The pia plexus is a
minute, tortuous, venous plexus which covers the entire surface of the cord, being
situated between the pia and arachnoid. "In this plexus there are six longitudinal
channels — one antero-median, along the anterior fissure — two antero-lateral,
immediately behind the anterior nerve roots — two postero-lateral, immediately
behind the posterior nerve roots — and one postero-median, over the postero-
septum" (Cunningham). These vessels are largest in the lumbar region. Near
the base of the skull they unite and form two or three small trunks, which com-
municate with the vertebral veins, and terminate in the subcerebellar veins or in
the subpetrosal sinuses. Each of the spinal nerves is accompanied by a branch
as far as the intervertebral foramina, where it joins the other veins from the spinal
canal.
There are no valves in the spinal veins.
VEINS OF THE LOWER EXTREMITY, ABDOMEN, AND PELVIS
(Figs. 467, 468).
The Veins of the Lower Extremity are subdivided, like those of the upper,
into two sets, superficial and deep, the superficial veins being placed beneath the
756 THE BLOOD -VASCULAR SYSTEM
integument, between the two layers of superficial fascia, the deep veins accom-
panying the arteries, and forming the venae comites of those vessels. Both sets
of veins are provided with valves, which are more numerous in the deep than in
the superficial set. These valves are also more numerous in the lower than in
the upper limb.
The Superficial Veins of the Lower Extremity.
The Superficial Veins of the Foot. — On the sole of the foot there is a sub-
cutaneous venous plexus (rete venosum plantar e cutaneum}, from which some
branches go to the deep veins, but most of the branches pass around the margins
to the dorsum of the foot. There is a transverse venous arch at the root of the
toes which receives plantar vessels from the toes and sends branches between the
toes (w. intercapitulares) to the venous arch of the dorsum. On the dorsum of each
toe the veins gather into two vessels, known as the dorsal digital veins (vv. digitales
pedis dorsales). The dorsal digital veins from the opposed margins of two toes
unite to form a dorsal interdigital vein. There are four dorsal interdigital veins
(vv. digitales communes pedis), and they pass into the venous arch of the dorsum.
The dorsal digital vein, from the inner surface of the great toe, passes directly
into the internal saphenous vein, and the dorsal digital vein, from the outer
surface of the little toe, passes directly into the external saphenous vein.
On the dorsum of the foot is a venous arch (arcus venosus dorsalis pedis
[cutaneus]), situated in the superficial structures over the anterior extremities of
the metatarsal bones. It has its convexity directed forward, and receives digital
tributaries from the upper surface of the toes; at its concavity it is joined by
numerous small veins which form a plexus on the dorsum of the foot (rete
venosum dorsale pedis cutaneum). The arch terminates internally in the long
saphenous, externally in the short saphenous vein.
The chief superficial veins of the lower extremity are the internal or long saphenous
and the external or short saphenous.
The Internal or Long Saphenous Vein (v. saphena magna) (Figs. 467 and 470)
commences at the inner side of the arch on the dorsum of the foot; it ascends in front
of the inner malleolus and along the inner side of the leg, behind the inner margin
of the tibia, accompanied by the internal saphenous nerve. At the knee it passes
backward behind the inner condyle of the femur, ascends along the inside of the
thigh, and, passing through the saphenous opening in the fascia lata, terminates
in the femoral vein about an inch and a half below Poupart's ligament. This vein
receives in its course cutaneous tributaries from the leg and thigh, and at the
saphenous opening receives the superficial epigastric, superficial circumflex iliac,
and external pudic veins. The veins from the inner and back part of the thigh
frequently unite to form a large vessel, which enters the main trunk near the
saphenous opening; and sometimes those on the outer side of the thigh join to form
another large vessel; so that occasionally three large veins are seen converging from
different parts of the thigh toward the saphenous opening. The internal saphenous
vein communicates in the foot with the internal plantar vein; in the leg, with the
posterior tibial veins by branches which perforate the tibial origin of the Soleus
muscle, and also with the anterior tibial veins; at the knee, with the articular
veins; in the thigh, with the femoral vein by one or more branches. The valves
in this vein vary from two to six in number; they are more numerous in the thigh
than in the leg.
The External or Short Saphenous Vein (v. saphena parva) (Fig. 468) com-
mences at the outer side of the arch on the dorsum of the foot; it ascends behind the
outer malleolus, and along the outer border of the tendo Achillis, across which it
passes at an acute angle to reach the middle line of the posterior aspect of the leg.
THE SUPERFICIAL VEINS OF THE LOWER EXTREMITY 757
Passing- directly upward, it perforates the deep fascia in the lower part of the
popliteal space, a'nd terminates in the popliteal vein, between the heads of the
I
andTtsbranchS8
FIG. 468. — External or short saphenous vein.
Gastrocnemius muscle.1 It receives numerous large
tributaries from the back part of the leg, and com-
municates with the deep veins on the dorsum of the
foot and behind the outer malleolus. Before it per-
forates the deep fascia it gives off a communicating
branch, which passes upward and inward to join the
internal saphenous vein. This vein has a variable
number of valves, from three to nine (Gay), one of
which is always found near its termination in the
popliteal vein. The external saphenous nerve lies
close beside this vein.
Surgical Anatomy. — The saphenous veins are of consider-
able surgical importance, since a varicose condition of these
vessels is more frequently met with than of those in other parts
1 Mr. Gay calls attention to the fact that the external saphenous vein often (he says invariably) penetrates
the fascia at or about the point where the tendon of the Gastrocnemius commences, and runs^below the fascia
in the rest of its course, or sometimes among the muscular fibres, to join the popliteal vein. (See Gay on Vari-
cose Disease of the Lower Extremities, p. 24, where there is also a careful and elaborate description of the
branches of the saphena veins.) — ED. of 15th English edition.
758
THE BLOOD -VASCULAR SYSTEM
of the body, except perhaps the spermatic and hemorrhoidal veins. The course of the internal
saphenous is in front of the tip of the inner malleolus, over the subcutaneous surface of the lower
end of the tibia, and then along the internal border of this bone to the back part of the internal
condyle of the femur, whence it follows the course of the Sartorius muscle, and is represented on
the surface by a line drawn from the posterior border of the Sartorius on a level with the internal
condyle to the saphenous opening. The external saphenous lies behind the external malleolus,
and from this follows the middle line of the calf to just below the ham. It is not generally so
apparent beneath the skin as the internal saphenous. Both these veins in the leg are accom-
panied
level
fact.
UI.VU* •^»V/lAV^l*V/AX IfUflrf LjiVAAi C*0 IrllVs AllbV/l UG*1 OCfcl^Ai^AiV^lAO* A^XSfeU CllA^O^ VJ^lllO 111 tllC ICii <* * ^ CHJULJl J.1™
sd by nerves, the internal saphenous being joined by its companion nerve just below the
of the knee-joint. No doubt much of the pain of varicose veins in the leg is due to this
The Deep Veins of the Lower Extremity.
The deep veins of the lower extremity accompany the arteries and their branches
and are called the venae comites of those vessels. The vense comites in the lower
extremity pass into one trunk, the popliteal vein,
whereas in the upper extremity the vense comites con-
tinue with the artery to the axilla.
The Deep Veins of the. Foot. — The plantar digital
veins (w. digitales plantar es) form the plantar metatarsal
veins (w. metaiarseae plantares), which communicate
with the veins of the dorsum of the foot by perfor-
ating veins and also communicate with the deep venous
arch of the sole of the foot (arcus venosus plantaris pro-
fundus). The plantar arch gives off lateral or external
plantar veins, which unite with median or internal plantar
veins to form the posterior tibial veins. On the dorsum
of the foot the deep veins begin as the dorsal metatarsal
veins (vv. metatarseae dorsales pedis}, wrhich form the
vense comites of the dorsalis pedis artery.
The Posterior Tibial Veins (vv. tibiales posteriores)
accompany the posterior tibial artery and are joined
by the peroneal veins.
The Anterior Tibial Veins (w. tibiales anterior es)
are formed by a continuation upward of the vense
comites of the dorsalis pedis artery. They pass be-
tween the tibia and fibula, through the large oval aper-
ture above the interosseous membrane, and form, by
their junction with the posterior tibial, the popliteal
vein.
The valves in the deep veins are very numerous.
The Popliteal Vein (v. poplitea) (Fig. 469) is formed
by the junction of the anterior and posterior tibial
veins; it ascends through the popliteal space to the
aperture in the Adductor magnus, where it becomes the femoral vein. In the
lower part of its course it is placed internal to the artery; between the heads of
the Gastrocnemius it is superficial to that vessel; but above the knee-joint it is
close to the outer side of the artery. It receives the sural veins from the Gastroc-
nemius muscle, the articular veins, and the external saphenous vein. The valves
in this vein are usually four in number.
The Femoral Vein (v. femoralis) (Figs. 470 and 471) accompanies the femoral
artery through the upper two-thirds of the thigh. In the lower part of its course
it lies external to the artery; higher up it is behind it; and at Poupart's ligament
it lies to its inner side and on the same plane. It receives numerous muscular
tributaries, and about an inch and a half below Poupart's ligament it is joined by
FIG. 469. — The popliteal vein.
(Poirier and Charpy.)
THE DEEP VEINS OF THE LOWER EXTREMITY
759
the profunda femoris (v. profunda femoris); near its termination it is joined by
the internal saphenous vein. The valves in this vein are four or five in number.
The External Iliac Vein (v. iliaca externa) (Figs. 464, 471 , and 473) commences
at the termination of the femoral, beneath the crural arch, and, passing upward
along the brim of the pelvis, terminates opposite the sacro-iliac synchondrosis by
uniting with the internal iliac to form the common iliac vein. On the right side it
lies at first along the inner side of the external iliac artery, but as it passes upward
gradually inclines behind it. On the left side it lies altogether on the inner side
of the artery. It receives, immediately above Poupart's ligament, the deep epi-
SUPERFICIAL
EPIGASTRIC
SUPERFICIAL
INTERNAL
CIRCUMFLEX
SUPERFICIAL
EXTERNAL
PUDIC
SUPERFICIAL
EXTERNAL
CIRCUMFLEX
FIG. 470. — The femoral vein and its tributaries. (Poirier and Charpy.)
gastric and deep circumflex iliac veins and a small pubic vein, corresponding to
the pubic branch of the obturator artery. According to Friedreich, it frequently
contains one and sometimes two valves.
The Deep Epigastric Vein (v. epigastrica inferior) (Fig. 471). — Two veins
accompany the deep epigastric artery; they usually unite into a single trunk
before their termination in the external iliac vein.
The Deep Circumflex Iliac Vein (v. circumflexa ilium profunda) (Fig. 471).—
Two veins accompany the deep circumflex iliac artery. These unite into a single
trunk which crosses the external iliac artery just above Poupart's ligament and
terminates in the external iliac vein.
760
THE BLOOD -VASCULAR SYSTEM
The Hypogastric or Internal Iliac Vein (v. iliaca interna or v. hypogastrica)
(Figs. 464, 471, and 473) is formed by the veins corresponding to all the branches
of the internal iliac artery except the umbilical branch. It receives the blood
from the exterior of the pelvis by the gluteal, sciatic, internal pudic, and obturator
veins, and from the organs in the cavity of the pelvis by the middle hemor-
rhoidal veins, the superior vesical plexus and the prostatico-vesical plexus in the
male, and the superior vesical, inferior vesical, uterine and vaginal plexuses in
the female. The vessels forming these plexuses are remarkable for their large size,
their frequent anastomoses, and the number of valves which they contain. The
internal iliac vein lies at first on the inner side, and then behind the internal iliac
artery, and terminates opposite the sacro-iliac articulation by uniting with the
external iliac to form the common iliac vein. This vessel has no valves.
The Internal Pudic Veins (vv. pudendoe internw) (Fig. 471) have the same course as
the internal pudic artery. They receive tributaries corresponding to the branches
of the artery, except the tributary corresponding to the dorsal artery of the
penis; that is, the deep dorsal vein of the penis, which opens into the prostatico-
vesical plexus.
CIRCUMFLEX
ILIAC
DEEP
EPIGASTRIC
LATERAL
SACRAL
MIDDLE
SACRAL
FIG. 471. — The iliac veins. (Poirier and Charpy.)
The Inferior or External Hemorrhoidal Veins (vv. hemorrhoidalis inferiores)
(Figs 472 and 473) collect blood from the anus. Tljey pass outward over the
External sphincter muscle, unite with numerous subcutaneous veins, and form
larger vessels which join the internal pudic veins.
The Middle Hemorrhoidal Veins (w. hemorrhoidalis media) (Figs. 472 and 473)
help to form the hemorrhoidal plexus, perforate the rectal wall, and empty into the
internal iliac vein. These veins, by their anastomoses in the hemorrhoidal plexus,
establish a communication between the portal and systemic venous systems.
The Lateral Sacral Veins (vv. sacrales laterales] (Fig. 471) accompany the lateral
sacral arteries and terminate in the internal iliac vein.
THE DEEP VEINS OF THE LOWER EXTREMITY
701
Surgical Anatomy. — The veins of the hemorrhoidal plexus are apt to become dilated and
varicose, and form piles, hemorrhoids. This is due to several anatomical reasons: the vessels are
contained in very loose, or connective tissue, so that they obtain less support from surrounding
structures than most other veins, and are less capable of resisting increased blood pressure:
the condition is favored by gravitation, being influenced by the erect posture, either sitting or
standing, and by the fact that the superior hemorrhoidal and portal veins have no valves. The
veins pass through muscular tissue and are liable to be compressed by its contraction, especially
during the act of defecation, and they are affected by every form of portal obstruction.
The Obturator Vein (v. obturatoriae) (Figs. 471 and 473) follows the course of
the obturator artery, lying below the artery as it passes over the side of the
pelvis; this vein empties into the front part of the internal iliac vein.
The Sciatic Veins are two in number; they accompany the sciatic artery in
the upper part of the back of the thigh, and just before their termination in the
internal iliac the two veins unite.
« The Gluteal Veins (vv. glutea) are usually two in number, and return to the
internal iliac vein the blood that has been distributed by the gluteal artery and
its branches.
SUPERIOR
HEMORRHOIDAL
MIDDLE
HCMORRHOiDAL'
INFERIOR,
HEMORRHOIDAL
FIG. 472. — Scheme of the anastomosis of the veins of the rectum. (Poirier and Charpy.)
The Superior Vesical Plexus (Fig. 473) is placed upon the fundus and
lateral aspects of the bladder on the external aspect of the muscular coat. It
receives vessels from the mucous membrane and from the muscular walls. It
empties into the internal pudic vein: in the male it communicates with the
prostatico-vesical plexus, and in the female with the inferior vesical plexus.
The Prostatic or the Prostatico-vesical Plexus "(Fig. 473) surrounds the
prostate gland and the neck of the bladder. It is contained between the recto-
vesical fascia which surrounds the base and sides of the gland and the true capsule
of the gland. It communicates with the superior vesical plexus behind and
above, and receives the deep dorsal vein of the penis, which enters the pelvis
between the subpubic and triangular ligaments. This plexus receives veins from
the seminal vesicles and vasa deferentia. On each side one or more vessels pass
762
THE BLOOD -VASCULAR SYSTEM
from the prostatico-vesical plexus to the internal iliac vein. The veins composing
the prostatic plexus are very liable to become varicose, and often contain hard,
earthy concretions called phleboliths.
The Inferior Vesical Plexus exists only in the female, and corresponds to the
prostatico-vesical plexus in the male, and surrounds the neck of the bladder and
the upper portion of the urethra. It receives the dorsal vein of the clitoris and
sends efferents to the internal iliac vein.
THIRD LUMBAR
SUPERIOR
HEMORRHOIDAL
DEEP
CIRCUMFLEX
ILIAC
OBTURATOR
PROSTATIC
PLEXUS
HEMORRHOIDAL
PLEXUS
MIDDLE
HEMORRHOIDAL
INFERIOR
HEMORRHOIDAL
DORSAL VEIN
OF PENIS
VESICAL PLEXUS
INTERNAL PUDIC
FIG. 473. — The veins of the male pelvis, right half, viewed from the left. The psoas muscle has been removed
and the rectum drawn down somewhat to the side. (Spalteholz.)
Surgical Anatomy. — The prostatico-vesical plexus is wounded in the lateral operation of
lithotomy, and it is through it that septic matter finds its way into the general circulation after
this operation. In enucleating the prostate the gland is shelled out from its capsule of recto-
vesical fascia. The veins of the plexus remain attached to the sheath.
The Dorsal Veins of the Penis. — The Superficial Dorsal Vein of the Penis (Fig.
474) receives blood from the prepuce and runs backward beneath the skin, and
divides into two branches which terminate in the superficial external pudic vein.
The Deep Dorsal Vein of the Penis (v. dorsalis penis) (Figs. 473 and 474) is a vessel
of large size which returns the blood from the body of that organ. At first it con-
THE DEEP VEINS OF Till-: LOWER EXTREMITY
7(33
SUPERFICIAL DOR-
SAL VEIN
DORSAL ARTERY j .DEEP DORSAL VEIN
CORPUS CAVERNOSUNT.
CAVERNOUS.. (.
ARTERY
sists of two branches, which are contained in the groove on the dorsum of the penis,
and it receives numerous superficial veins and veins from the glans penis and the
corpus spongiosum. These vessels unite into a single trunk, which passes between
the two parts of the suspensory ligament of the penis, and through an aperture
between the subpubic ligament and
the apex of the triangular ligament,
and divides into two branches, which
enter the prostatico-vesical plexus.
The dorsal vein of the clitoris corre-
sponds in woman to the dorsal vein
of the penis in man, and runs into
the inferior vesical plexus.
The Vaginal Plexuses and Veins
(Fig. 475). — The vaginal plexuses are
placed at the sides of the vagina, being
especially developed at the orifice of
the canal. They receive vessels from
the vaginal walls. The plexuses
communicate with the uterine plexus above, with the bulbar veins below, with
the inferior vesical plexus in front and with the hemorrhoidal plexus behind.
From the upper part of each vaginal plexus comes a vaginal vein which passes
to the internal iliac.
The Uterine Plexuses (Fig. 475) are situated along the sides and superior angles
of the uterus, between the layers of the broad ligament. They receive the veins
from the uterus, which veins are without valves. During pregnancy these veins
DEEP
FASCIA
BULBO-CAVERNOUS ARTERY/
-ANTERIOR BRANCH
CORPUS
SPONGIOSUM
FIG. 474. — The penis in transverse section, showing the
blood-vessels. (Testut.)
URETHRA
TUBAL VESSELS
NASTOMOSIS OF
UTERINE AND
OVARIAN ARTERIES
UTERINE
VEINS
VAGINAL VENOUS PLEXUS
TERINE ARTEHY
"-SUPERIOR VAGINAL
ARTERIES
os UTERI' VAGINA CUT OPEN BEHIND
FIG. 475. — Vessels of the uterus and its appendages, rear view. (Testut.)
become large venous canals known as the uterine sinuses, and bring blood from the
substance of the placenta. These veins join the ovarian above and the vaginal
below, and anastomose with each other. They are not tortuous like the artery.
The Uterine Veins (vv. uterinae) (Fig. 475) arise from the lower part of the
plexus, and there are usually two veins on each side and they are without valves.
These veins for the first portion of their course are placed in the base and inner
portion of the broad ligament; they then pass back with the uterine artery in a
peritoneal fold between the back of the broad ligament and the recto-uterine
fold (Cunningham) ; they then pass upward and enter the internal iliac vein.
764 THE BLOOD -VASCULAR SYSTEM
The Common Iliac Vein (v. iliaca communis) (Figs. 464, 471, and 473) on
each side is formed by the union of the external and internal iliac veins in
front of the sacro-iliac articulation: passing obliquely upward teward the right
side, each vein terminates upon the intervertebral substance between the fourth
and fifth lumbar vertebrae, where the veins of the two sides unite at an acute
angle to form the postcava or inferior vena cava. The right common iliac (v. iliaca
communis dextra) is shorter than the left, nearly vertical in its direction, and ascends
behind and then to the outer side of its corresponding artery. The left common
iliac (v. iliaca communis sinistra), longer and more oblique in its course, is at first
situated on the inner side of the corresponding artery, and then behind the right
common iliac. Each common iliac receives the ilio-lumbar, and sometimes the
lateral sacral, veins. The left receives, in addition, the middle sacral vein. No
valves are found in these veins.
The Middle Sacral Veins (Figs. 471 and 472) accompany the corresponding
artery along the front of the sacrum, and join to form a single vein (v. sacralis
media), which terminates in the left common iliac vein; occasionally in the angle
of junction of the two iliac veins. The middle sacral veins communicate with
the inferior hemorrhoidal.
The Ilio-lumbar Veins (vv. iliolumbales) receive branches from the iliac fossae,
spinal muscles, and spinal canal. One vein on each side runs with the artery,
passes posterior to the psoas muscle, and joins the common iliac vein.
Peculiarities. — The left common iliac vein, instead of joining with the right in its usual
position, occasionally ascends on the left side of the aorta as high as the kidney, where, after
receiving the left renal vein, it crosses over the aorta, and then joins with the right vein to form
the postcava. In these cases the two common iliacs are connected by a small communicating
branch at the spot where they are usually united.1
The Postcava, Ascending, or Inferior Vena Cava (v. cava inferior) (Figs. 464
and 471) returns to the heart the blood from all the parts below the Diaphragm. It
is formed by the junction of the two common iliac veins on the right side of the
intervertebral substance between the fourth and fifth lumbar vertebrae. It passes
upward along the front of the spine on the right side of the aorta, and, having
reached the under surface of the liver, is contained in a groove on its posterior sur-
face. It then perforates the central tendon of the Diaphragm, enters the peri-
cardium, where it is covered for a very short distance by the serous layer of the
pericardium, and terminates in the lower and back part of the right auricle. At
its termination in the auricle it is provided with a valve, the Eustachian valve
(valvula v. cavae inferioris [Eustachii]), which is of large size during total life.
Relations. — In front, from below upward, with the mesentery, right spermatic
artery, transverse portion of the duodenum, the pancreas, portal vein, and the
posterior surface of the liver, which, in most cases, partly and occasionally com-
pletely surrounds it; behind, with the vertebral column, the right crus of the
Diaphragm, the right renal and lumbar arteries, and the right semilunar ganglion;
on the left side, with the aorta.
Peculiarities. In Position. — This vessel is sometimes placed on the left side of the aorta,
as high as the left renal veins, after receiving which it crosses over to its usual position on the
right side; or it may be placed altogether on the left side of the aorta, as far upward as its ter-
mination in the heart: in such cases the abdominal and thoracic viscera, together with the great
vessels, are all transposed.
Point of Termination.— Occasionally the postcava joins the right azygos vein, which is then
of large size. In such cases the precava receives the whole of the blood from the body before
transmitting it to the right auricle, except the blood from the hepatic veins, which passes
directly into the right auricle.
i See two cases which have been described by Mr. Walsham in St. Bartholomew's Hospital Reports, vols.
xvi. and xvii. — ED. of 15th English edition.
THE DEEP VEINS OF THE LOWER EXTREMITY 765
Tributaries. — It receives in its course the following veins:
Lumbar. Suprarenal.
Right Spermatic. Phrenic.
Renal. Hepatic.
The Lumbar Veins (w. lumbales), four in number on each side, collect the
blood by dorsal tributaries from the muscles and integument of the loins and by
abdominal tributaries from the walls of the abdomen, where they communicate
with the epigastric veins. At the spine they receive veins from the spinal plexuses,
and then pass forward, round the sides of the bodies of the vertebrae beneath the
FIG. 476. — Spermatic veins. (Testut.)
Psoas magnus muscle, and terminate at the back part of the postcava. The
left lumbar veins are longer than the right, and pass behind the aorta. The lumbar
veins of a side are connected together by a longitudinal vein which passes in front
of the transverse processes of the lumbar vertebras, and is called the ascending
lumbar vein (v. lumbalis ascendens) (Fig. 464). It forms the most frequent origin
of the corresponding vena azygos, and serves to connect the common iliac, ilio-
lumbar, lumbar, and azygos veins of the corresponding side of the body.
The Spermatic Veins (vv.spermaticae)(F'\g. 476) emerge from the back of the testis,
and receive tributaries from the epididymis; they unite and form a convoluted
plexus called the spermatic plexus (plexus pampiniformis) , which forms the chief
760
THE BLOOD -VASCULAR SYSTEM
mass of the cord : the vessels composing this plexus are very numerous, and ascend
along the cord in front of the vas deferens; below the external abdominal ring they
unite to form three or four veins, which pass along the inguinal canal, and, enter-
ing the abdomen through the internal abdominal ring, coalesce to form two veins,
which ascend on the Psoas muscle behind the peritoneum, lying one on each side
of the spermatic artery, and unite to form a single vein, which opens on the right
SPERMATIC VEIN-
LEFT SIDE
SPERMATIC VEIN — __
RIGHT SIDE
FIG. 477. — Terminations of the right and left spermatic veins. (Poirier and Charpy.)
side into the postcava at an acute angle; on the left side into the left renal vein
at a right angle (Fig. 477). The termination of the left spermatic vein is called
the emulgent vein. Professor John H. Brinton pointed out that a valve is usually
absent in the emulgent vein (Fig. 478), but regularly present in the right spermatic
vein.1 The left spermatic vein passes behind the sigmoid flexure of the colon,
and is thus exposed to pressure from the contents of that bowel.
Surgical Anatomy. — The spermatic veins are very frequently varicose, constituting the dis-
ease known as varicocele. Though it is quite possible that the originating cause of this affection
may be a congenital abnormality either in the size or number of the veins of the pampiniform
plexus, still it must be admitted that there are many anatomical reasons why these veins should
become varicose — viz., the imperfect support afforded to them by the loose tissue of the scrotum;
their great length; their vertical course; their dependent position; their plexiform arrangement
in the scrotum, with their termination in one small vein in the abdomen; their few and imperfect
valves ; and the fact that they may be subjected to pressure in their passage through the abdominal
wall. The left veins more often become varicose than the right veins, probably, as Brinton sug-
gests, because the right spermatic vein practically always has a valve and opens into the post-
cava at an acute angle, whereas the left spermatic vein is not unusually destitute of a valve at
its opening and passes into the left renal vein at a right angle.
The Ovarian Veins (vv. ovaricae) (Fig. 475) are analogous to the spermatic in the
male; they form a plexus near the ovary in the broad ligament and about the Fallo-
pian tube, communicating with the uterine plexus. They terminate in the same way
as the spermatic veins in the male. Valves are occasionally found in these veins.
These vessels, like the uterine veins, become much enlarged during pregnancy.
1 See John H. Brinton in the American Journal of the Medical Sciences, and also Handbuch der Topographi-
schen Anatomie.von Joseph Hyrtl. Rivington maintains that a valve is usually found at the orifices of both the
right and left spermatic veins. When no valves exist at the opening of the left spermatic vein into the left renal
vein, valves are generally present in the left renal vein within a quarter of an inch from the orifice of the
spermatic vein. (Journal of Anatomy and Physiology, vol. vii. p. 163). — ED. of 15th English edition.
THE DEEP VrEINS OF THE LOWER EXTREMITY
767
The Renal Veins (vv. renales) (Fig. 465) are of large size, and are placed in front
of the renal arteries.1 The left is longer than the right, and passes in front of the
aorta, just below the origin of the superior mesenteric artery. It receives the left
spermatic, the left inferior, and, generally, the left suprarenal veins. It opens into
the postcava a little higher than the right. The utero-venous triangle of Robinson
is formed by the ureter, the renal veins, and the ovarian veins.
The Suprarenal Veins (vv. suprarenales) (Fig. 464) are two in number: that on
the right side terminates in the postcava; that on the left side, in the left renal
or in the left phrenic vein.
The Phrenic Veins (vv. phrenicae} follow the course of the phrenic arteries.
The two superior phrenic veins (vv. phrenicae superiores), of small size, accom-
pany the phrenic nerve and comes nervi phrenici artery, and join the internal
in the left renal vein. (John H. Brinton.)
mammary vein. The two inferior phrenic veins (w. phrenicae inferiores) follow
the course of the phrenic arteries, and terminate, the right in the postcava, the
left in the left renal vein.
The Hepatic Veins (vv. hepaticae) commence in the substance of the liver, in
the capillary terminations of the portal vein and hepatic artery, intralobular veins:
these tributaries, gradually uniting into sublobular veins; usually form three large
hepatic veins, which converge toward the posterior surface of the liver and open
into the postcava, whilst that vessel is situated in the groove at the back part of
this organ. Of these three veins, one from the right and another from the left
1 The student may observe that all veins above the Diaphragm, which do not lie on the same plane as the
arteries which they accompany, lie in front of them, and that all veins below the Diaphragm, which do Tiot
lie on the same plane as the arteries which they accompany, lie behind them, except the renal and profunda
femoris vein. — ED. of 15th English edition.
768 THE BLOOD-VASCULAR SYSTEM
lobe open obliquely into the postcava, that from the middle of the organ and
lobulus Spigelii having a straight course. The hepatic veins run singly, and are
in direct contact with the hepatic tissue. They are destitute of valves.
The Portal System of Veins (Fig. 479).
The portal venous system is composed of four large veins which collect the
venous blood from the viscera of digestion (stomach, intestine, and pancreas) and
from the spleen. The trunk formed by their union, the portal vein, enters the liver
and ramifies throughout its substance after the manner of an artery and ends
in capillaries, from which the blood is collected into the hepatic veins, which
terminate in the postcava. The branches of this vein are in all cases single, and
destitute of valves.
The veins forming the portal system are — -the
Superior Mesenteric. Inferior Mesenteric.
Splenic. Gastric.
Cystic.
The Superior Mesenteric Vein (v. mesenterica superior} (Fig. 479) returns the
blood from the small intestines and from the caecum and ascending and transverse
portions of the colon, corresponding with the distribution of the branches of the
superior mesenteric artery. The large trunk formed by the union of these branches
ascends along the right side and in front of the corresponding artery, passes in front
of the transverse portion of the duodenum, and unites, behind the upper border
of the pancreas, with the splenic vein to form the portal vein. It receives the
right gastro-epiploic vein. The appendicular vein is a tributary of the superior
mesenteric vein.
The Splenic Vein (v. lienalis) (Fig. 479) commences by five or six large branches
which return the blood from the substance of the spleen. These, uniting, form a
single vessel, which passes from left to right, grooving the upper and back part of
the pancreas below the artery, and terminates at its greater end by uniting at a
right angle with the superior mesenteric to form the portal vein. The splenic vein
is of large size, and not tortuous like the artery. It receives the vasa brevia from
the left extremity of the stomach, the left gastro-epiploic vein, pancreatic branches
from the pancreas, the pancreatico-duodenal vein, and the inferior mesenteric vein.
The Inferior Mesenteric Vein (v. mesenterica inferior} (Fig. 479) returns the
blood from the rectum, sigmoid flexure, and descending colon, corresponding with
the ramifications of the branches of the inferior mesenteric artery. It lies to the left
of the artery, and ascends beneath the peritoneum in the lumbar region; it passes
behind the transverse portion of the duodenum and pancreas, and terminates in
the splenic vein. Its hemorrhoidal branches, the superior hemorrhoidal veins (w.
hemorrhoidalis superior), inosculate with the middle hemorrhoidal branches of the
internal iliac, and thus establish a communication between the portal and the
general venous system.1
The Gastric Veins (w. gastricae) (Fig. 479) are two in number : one, a small vein,
corresponds to the pyloric branch of the hepatic artery; the other, considerably
larger, corresponds to the gastric artery. The former, the pyloric vein (v. pylorica),
runs along the lesser curvature of the stomach toward the pyloric end, receives
branches from the pylorus and duodenum, and ends in the portal vein. The
latter, the gastric or coronary vein (v. coronaria ventriculi), begins near the pylorus,
THE PORTAL SYSTEM OF VEINS
769
runs along the lesser curvature of the stomach toward the oesophageal opening
in the diaphragm, and then passes across the front of the spine from left to right
to end in the portal vein, at a point a little above the junction of the pyloric vein.
The Cystic Vein (y. cystica) (Fig. 479). — The portal vein generally receives the
cystic vein, although that vessel sometimes terminates in the right branch of the
portal vein.
FIG. 479. — Portal vein and its branches.
NOTE. — In this diagram the right gastro-epiploic vein opens into the splenic vein; generally
it empties itself into the superior mesenteric, close to its termination.
The Portal Vein (vena portae)(F\g. 479) is formed by the junction of the superior
mesenteric and splenic veins, their union taking place in front of the vena cava and
behind the upper border of the head of the pancreas. Passing upward through
the right border of the lesser omentum to the under surface of the liver, it enters
the transverse fissure, where it is somewhat enlarged, forming the sinus of the
portal vein, and divides into two branches which accompany the ramifications of
the hepatic artery and hepatic duct throughout the substance of the liver. Of
49
770
THE BLOOD -VASCULAR SYSTEM
these two branches, the right is the larger, but the shorter, of the two. The portal
vein is about three or four inches in length, and, whilst contained in the lesser
omentum, lies behind and between the common bile-duct and the hepatic artery,
the former being to the right, the latter to the left. These structures are accom-
panied by filaments of the hepatic plexus of nerves and numerous lymphatics,
and are surrounded by a quantity of loose areolar tissue, the capsule of Glisson.
The portal vein divides, in the substance of the liver, like an artery, and its
minute ramifications end in capillaries, from which the blood is carried to the
postcava by the hepatic veins; these veins also collect the blood which has been
brought to the liver by the hepatic artery. It will therefore be seen that the blood
which is carried to the liver by the portal vein passes through two sets of capillary
vessels— vi z. : (1) the capillaries in the stomach, intestine, pancreas, and spleen,
and (2) the capillaries of the portal vein in the liver.
THE CARDIAC VEINS (Fig. 480).
The veins which return the blood from the substance of the heart are — the
Great Cardiac Vein.
Posterior Cardiac Vein.
Left Cardiac Veins.
Anterior Cardiac Veins.
Right or Small Coronary Vein.
Coronary Sinus.
Venae Thebesii.
The Great Cardiac or Left Coronary Vein (v. cordis magna) is a vessel of
considerable size, which commences at the apex of the heart, and ascends along
the anterior interventricular groove to the base of the ventricles. It then curves
PULMONARY
VEINS
LEFT AURICULAR,
APPENDIX
RIGHT CORONARY ARTERY
AURICULAR- VENTRICULAR
GROOVE
CORONARY..
SINUS
LEFT
VENTRICLE'
•VENA AZYGOS
MAJOR
.PULMONARY
VEINS
LEFT
AURICLE
POSTERIOR CARDIAC1
VEIN
POSTERIOR
RIGHT CORONARY
iRTERY DESCEND"
INQ BRANCH
ULAR GROOVE VENTRICLE
FIG. 480. — Cardiac veins, dorsal view. (Testut.)
to the left side, around the auriculo-ventricular groove, between the left auricle
and ventricle, to the back part of the heart, and opens into the left extremity
of the coronary sinus, its aperture being guarded by two valves. It receives, in
THE CARDIAC VEINS 771
its course, tributaries from both ventricles, but especially from the left, and also
from the left auricle; one of these ascending along the thick margin of the left
ventricle is of considerable size, and is called the left marginal vein. The vessels
joining the great cardiac vein are provided with valves.
The Posterior or Middle Cardiac Vein (v. cordis media) commences by small
tributaries, at the apex of the heart, communicating with those of the preceding.
It ascends along the posterior interventricular groove to the base of the heart,
and terminates in the coronary sinus, its orifice being guarded by a valve. It
receives veins from the posterior surface of both ventricles.
The Left Cardiac Vein (v. posterior ventriculi sinistri) receives three or four
small vessels, which collect the blood from the posterior surface of the left ven-
tricle. It opens into the lower border of the coronary sinus.
The Anterior Cardiac Veins (vv. cordis anteriores) are three or four small
vessels, which collect the blood from the anterior surface of the right ventricle.
One of these, the vein of Galen, larger than the rest, runs along the right border
of the heart. They open separately into the lower part of the right auricle.
The Right Cardiac or Small Coronary Vein (v. cordis parva) runs along the
groove between the right auricle and ventricle, to open into the right extremity of
the coronary sinus. It receives blood from the back part of the right auricle and
ventricle.
The Coronary Sinus (sinus coronarius) is that portion of the anterior or great
cardiac vein which is situated in the posterior part of the left auriculo-ventricular
groove. It is about an inch in length, presents a considerable dilatation, and is
covered by the muscular fibres of the left auricle. It receives most of the veins of
the heart. Besides those mentioned it receives the oblique vein of Marshall (v. obliqua
atrii sinistri) from the back part of the left auricle, the remnant of the obliterated
left Cuvierian duct of the foetus, described by Mr. Marshall. The great coronary
sinus terminates in the right auricle, between the postcava and the auriculo-
ventricular aperture, its orifice being guarded by a semilunar fold of the lining
membrane of the heart, the Thebesian valve. All the veins joining this vessel,
excepting the oblique vein above mentioned, are provided with valves.
The Venae Thebesii (venae cordis minimae) are numerous minute veins, which
return the blood directly from the muscular substance, without entering the venous
current. They open by minute orifices, foramina Thebesii (foramina venarum
minamarum), chiefly on the inner surface of the right auricle.
THE LYMPHATIC SYSTEM.
LYMPH is obtained from the blood-plasma. From lymph the body cells obtain
food, into lymph they discharge their waste materials, and there is a distinct
lymphatic circulation, the constituents of the plasma passing into the perivascular
lymph-spaces and returning to the heart by way of the lymphatics and certain
veins.
The lymphatic system consists of lymphatic glands — large lymph- vessels, small
lymph- vessels (lymphatic capillaries], the perivascular lymph-spaces, the lymph
canalicular system, and the body cavities. To this system also belong the lacteal or
chyliferous vessels. The lacteals are the lymphatic vessels of the small intestine,
and differ in no respect from the lymphatics generally, excepting that during the
process of digestion they contain a milk-white fluid, the chyle, which passes into
the blood through the thoracic duct.
The lymph canalicular system is the system of spaces in areolar connective
tissue. The spaces are called lymph-spaces, and are found practically in every
region of the body. In these spaces lie the cells of the tissue. The larger spaces
are lined with endothelium, the smaller spaces are not lined with endothelium;
they form connections with each other by anastomotic channels and constitute a
system of spaces and channels which many observers believe join the lymphatic
capillaries. Others maintain that lymph-spaces are not direct continuations or
expansions of lymph-capillaries, but that networks of lymphatic capillaries exist
in the tissue immediately around each space, an arrangement which permits of
interchange between the contents of a space and the contents of the surrounding
capillaries. Mall seems to have proved this by his experimental injections into
the portal vein. He showed that colored fluid injected into the portal vein passes
through the walls of the venous capillaries, enters the lymph-spaces, and finally gets
into the lymph-capillaries of the liver.
The perivascular lymph-spaces are found around certain blood-vessels. Each
space is lined with endothelium, and is joined to other spaces by trabeculse of con-
nective tissue. The spaces form a system, and the fluid in these spaces reaches the
lymphatic capillaries. Perivascular lymph-spaces have been demonstrated in the
Haversian canals and in the subdural space of the pia.
The pleural, pericardial, peritoneal, and synovial cavities are lined by endothelial
cells. Beneath the layer of lining cells are lymph-spaces or lymph -vessels. It was
long thought that these lymph-vessels communicate directly with the body cavity
by means of numerous openings in the lining membrane. This view is probably
incorrect. The subarachnoid space/the subdural space, the cavity for the aqueous
humor of the eye, the cavity for the vitreous humor, and the space of Tenon are
probably lymph-spaces.
Lymph-capillaries are arranged in networks, are larger than blood-capillaries,
but the diameter of a lymph -capillary is different at different points, at some places
being much larger than at others. Lymph-capillaries are formed of flattened
endothelial cells. In some situations networks of lymphatic capillaries surround
the blood-vessels. The lymph-vessels are called the lymphatics.
The lymphatics have derived their name from the appearance of the fluid con-
tained in their interior (lympha, water). They are also called absorbents, from the
(772)
THE LYMPHATIC SYSTEM 773
property they possess of absorbing certain materials from the tissues and con-
veying them into the circulation. Larger lymphatics are called trunks and the
largest are called ducts.
The lymphatics are exceedingly delicate vessels, the coats of which are so
transparent that the fluid they contain is readily seen through them, and they
appear milky-white; hence the name Asellius gave them of lacteal veins. They
retain a nearly uniform size, and may be cylindrical in shape, but usually are inter-
rupted at intervals by constrictions which give them a knotted, beaded, or sac-
like appearance. These constrictions are due to the presence of valves in the
interior of the vessel. Lymphatic vessels do not invariably contain valves. Valves
are absent at the starting points of lymphatics, are absent in lymphatic capillaries,
are not numerous in the largest ducts (thoracic duct), and are seldom found in vis-
ceral lymphatics. The valves are not found in fixed situations and vary in number.
Between the ends of the fingers and the axillary glands Sappey counted from sixty
to eighty. "They are arranged in pairs and resemble the aortic semilunar valves."1
The lymphatic capillaries are composed purely of endothelium, but the collecting
trunks possess not only an endothelial inner coat, but an investing elasto-muscular
coat. Vessels in the subcutaneous connective tissue are devoid of muscle. Lymph-
atics have been found in nearly every texture and organ of the body which contains
blood-vessels. Such non-vascular structures as cartilage, the nails, cuticle, and
hair have none, but with these exceptions it is probable that eventually all parts
will be found to be permeated by these vessels.
A larger lymphatic vessel is composed of three coats. The inner coat is
composed of elastic tissue lined with endothelium. The middle coat is com-
posed of elastic and muscular fibres. The external coat is composed of connec-
tive tissue intermixed with smooth muscular fibres longitudinally or obliquely
placed.
The thoracic duct possesses a subendothelial layer of connective tissue like that
found in the arteries, and in the middle coat there is a longitudinal layer of
connective tissue. The wall of a smaller lymphatic contains no elastic and no
muscular tissue, and consists merely of connective tissue lined with endothelium.
The lymphatics are arranged in superficial and deep sets. The superficial lym-
phatics, on the surface of the body, are placed immediately beneath the integument,
accompanying the superficial veins; they join the deep lymphatics in certain situa-
tions by perforating the deep fascia. In the interior of the body the lymphatics
lie in the submucous areolar tissue throughout the whole length of the gastro-
pulmonary and genito-urinary tracts, and in the subserous tissue of the thoracic
and abdominal cavities. In the cranial cavity the perivascular sheaths are lymph-
spaces. A plexiform network of minute, closed, capillary lymphatics may be found
interspersed among the proper elements and blood-vessels of the several tissues, the
vessels composing which, as well as the meshes between them, are much larger than
those of the capillary blood-vessel plexus. From these networks small collecting
vessels emerge, pass to a neighboring gland, and divide into a capillary network
in the gland. Numerous small vessels emerge from the gland, which unite into
one lymphatic vessel, which joins a larger lymphatic trunk, which empties into
a branch of the precava. The deep lymphatics, fewer in number and larger than
the superficial, accompany the deep blood-vessels. Their mode of origin is prob-
ably similar to that of the superficial vessels. The lymphatics of any part or organ
exceed the veins in number and in capacity, but in size they are much smaller.
Their anastomoses also, especially those of the large trunks, are more frequent,
and are effected by vessels equal in diameter to those which they connect. The
continuous trunks retain the same diameter throughout. As the lymphatic vessels
1 A Treatise on Anatomy. By P. Poirier and A. Charpy. Article on the Lymphatics. By G. Delamare,
P. Poirier, and B. Cune"o.
774
THE LYMPHATIC SYSTEM
approach their point of discharge their number diminishes, but the calibre of the
remainder does not increase in proportion.
The gaps in the connective tissue, the larger of which are lined with endothelium,
the smaller of which are devoid of endothelial lining, are known as lymphatic
spaces. (See page 772.)
The lymphatic or absorbent glands (lymphoglandulae) , named also conglobate
glands and lymph-nodes, are small, solid, glandular bodies situated in the course of
the lymphatic and lacteal vessels. They vary from microscopic dimensions to the
size of an olive, and their color, on section, is of a pinkish-gray tint, excepting the
bronchial glands, which in the adult are mottled with black, the hepatic glands,
which are yellow, and the splenic glands, which are brown. Each gland has
a layer or capsule of cellular tissue investing it, from which prolongations dip
into its substance, forming partitions. The lymphatic and lacteal vessels pass
through these glands in their passage to the lymph-
atic ducts. A lymphatic or lacteal vessel, previous to
entering a gland, divides into several small branches,
which are named afferent vessels (vasa afferentia}.
As they enter the gland, the external coat of each
becomes continuous with the capsule of the gland,
and the vessels becoming much thinned, and consist-
ing only of their internal or endothelial coat, pass
into the gland, and branch out upon and in the tissue
of the capsule, these branches opening into the lymph-
sinuses of the gland. There is an extensive sinus
beneath the capsule; from this subcapsular sinus
numerous branches run inward to a central sinus.
From both sinuses fine branches proceed to form a
plexus, the vessels of which unite to form a single
efferent vessel (vas efferens), which, on emerging
from the gland, is again invested with an external
coat from the gland capsule. The lymph-glands are
filters through which lymph and chyle flow. Car-
cinoma cells are caught in them, and the dissemina-
tion of the disease is retarded. In the glands are
masses of newly formed leukocytes which attack any
bacteria in the lymph or chyle.
The size of the lymphatic glands decreases as age
advances, and in very old individuals many glands
actually disappear. It is impossible to estimate the
number of macroscopic glands. Sappey estimated the number to be from 600 to
700. Glands are embedded in fat and are distinctly movable. Some of them are
superficial (above the deep fascia); others are deep (below the deep fascia).
Occasionally a gland exists alone, but, as a rule, they are assembled in com-
munities or chains of from eight to twelve, or even more. They are usually
arranged around vessels, and often are upon vessels. The glands have a plen-
tiful blood-supply, and contain not only vascular nerves, but definite nerve-
plexuses. Besides the glands, the body contains numerous lymphoid areas,
which, in structure and function, are allied to lymph-glands (tonsils, Peyer's
patches, etc.).
Hemolymph nodes exist in various regions, but are most common in the abdomen
in front of the vertebras. They are like ordinary lymph-nodes in form and also in
size, but differ from them in being deep red instead of light pink. Some regard
hemolymph nodes as structures like the spleen; others regard them as very vas-
cular but otherwise ordinary nodes.
FIG. 481. — A lymph-node with its
afferent and efferent vessels. (Tes-
tut.) •
THE THORACIC AND RIGHT LYMPHATIC DUCT
775
Surgical Anatomy. — In an operation for cancer it is not sufficient to cut wide of the growth
and remove it; it is imperatively necessary to remove the lymphatic glands which receive lymph
from the diseased area, and also, when possible, the lymphatic vessels between the cancer and
the glands. Glands are diseased very early in cancer, long before they are palpably enlarged,
and are usually infected by emboli of can-
cer cells. The rule is in any cancer, how-
ever recent, to regard the associated glands
as diseased, whether enlarged or not, and
to thoroughly remove them, if possible, in
one piece, with the intervening lymph-ves-
sels and the area of primary malignant
growth.
Bight
lymphatic
duct.
THE THORACIC DUCT AND
THE RIGHT LYMPHATIC
DUCT.
The thoracic duct or the left
lymphatic duct (ductus thoracicus)
(Fig. 482) conveys the great mass
of lymph and chyle into the blood.
It is the common trunk of all the
lymphatic vessels of the body below
the Diaphragm, and usually, but not
always, also receives the lymph from
the left side of the body above the
Diaphragm. It does not drain the
right side of the head and neck,
the right upper extremity, the right
lung, right side of the 'heart, and the
convex surface of the liver. It partly
drains the right chest wall. It varies
in length from fifteen to eighteen
inches in the adult, and extends from
the second lumbar vertebra to the
root of the neck. The duct is formed
by the union of the right and left
lumbar trunks (trunci lumbales),
from the lumbar lymph-nodes. The
left lumbar trunk also obtains lymph
from the creliac and mesenteric
nodes. A little distance above its
origin the thoracic duct usually pre-
sents a triangular dilatation, the
receptaculum chyli or the reservoir
or cistern of Pecquet (cisterna chyli},
which is situated upon the front of
the bodies of the first and of the sec-
ond lumbar vertebra?, to the right
side and behind the aorta, by the
side of the right crus of the Dia-
phragm. The receptaculum is
absent in some individuals. The thoracic duct ascends into the thorax through
the aortic opening in the Diaphragm, lying to the right of the aorta, and is placed
in the posterior mediastinum in front of the vertebral column, lying between the
aorta and vena azygos major. Opposite the fourth thoracic vertebra it inclines
FIG. 482. — The thoracic and rirfit lymphatic ducts.
776
THE LYMPHATIC SYSTEM
toward the left side, and ascends behind the arch of the aorta on the left side of
the oesophagus, and behind the first portion of the left subclavian artery, to the
upper orifice of the thorax. Opposite the seventh cervical vertebra it turns out-
ward and then curves downward over the subclavian artery and in front of the
Scalenus anticus muscle, so as to form an arch, and terminates in the left sub-
clavian vein at its angle of junction with the left internal jugular vein. It usually
opens at the apex of the angle in the superior and outer surface, but may open
on the posterior surface. Sometimes it terminates by two branches. Figs. 482
and 484 show the termination of the thoracic duct. The thoracic duct, at
its commencement, is about equal in diameter to that of a goose-quill, dimin-
ishes considerably in its calibre in the middle of the thorax, and is again
dilated just before its termination, the ampulla. It is generally flexuous in its
course, the older the person the greater the flexuosity, and it is constricted at inter-
vals so as to present a varicose appearance. The thoracic duct not infrequently
divides in the middle of its course into two branches of unequal size, which
soon reunite, or divides into several branches, which form a plexiform interlace-
ment. It occasionally divides, at its upper part, into two branches, of which the
one on the left side terminates in the usual manner, while that on the right opens
into the right subclavian vein, in connection with the right lymphatic duct. The
thoracic duct has several valves throughout its whole course, but they are more
numerous in the upper than in the lower part, and the lower valves are not com-
petent; at its termination it is provided with a pair of competent valves, the free
borders of which are turned toward the vein, so as to prevent the passage of
venous blood into the duct.
The common intestinal trunk (truncus intestinalis) (Figs. 482, 483, and 509)
empties into the receptaculum and brings lymph from the small intestine (lacteals),
the stomach, the pancreas, and the spleen.
Radicals of Origin and Tributaries. — In most individuals the juxta-aortic
glands which are placed on each side of the aorta send a vessel upward and
inward, which unite to form the thoracic duct. The right vessel is known as
the truncus lymphaticus lumbalis dextra. The left vessel is known as the truncus
lymphaticus lumbalis sinistra. A vessel from the glands in front of (pre-aortic)
and back (retro-aortic) of the aorta empties into each of the above-named vessels.
In some cases a large vessel forms from the glands in front of the aorta and helps
form the duct. The receptaculum chyli receives the common intestinal lymphatic
trunk, which conveys lymph from the small intestine, stomach, spleen, pancreas,
and a portion of the liver.
FIG. 483. — Modes of origin of the thoracic duct, o, - - . . .
trunk of the efferents of the right juxta-aortic glands; c, common trunk of the efferent s
the downward course. (Poirier and Charpy.)
THE RIGHT LYMPHATIC DUCT
777
The branches of the left lymphatic duct are: 1. A descending trunk, which
collects lymph from the posterior intercostal glands of the seven lower inter-
costal spaces. 2. A trunk is formed by vessels coming from the superior juxta-
aortic glands beneath the Diaphragm. 3. The lymphatic vessels form the upper
five intercostal spaces. 4. The lymphatic vessels form the posterior mediastinal
glands and retrosternal glands. 5. The left jugular trunk (truncus jugularis),
although this may open directly into the junction of the subclavian and internal
jugular veins. 6. In rare cases the thoracic duct receives near its termination
the left subclavian trunk (truncus subclavius) and a broncho-mediastinal trunk.
As a rule, however, the two last-mentioned trunks empty into the jugulo-subclavian
junction separately or as one duct.
The thoracic duct receives the lymph from the extremities, the deep portion
of the abdominal wall and of the pelvic wall, the pelvic viscera, the kidneys and
suprarenal capsules, the large intestine, the small intestine, the walls of the
thoracic cavity, the under surface and anterior portion of the liver, the stomach,
the spleen, the pancreas, the sternal and intercostal glands, the left lung, left
side of the heart, trachea, and oesophagus, and often, just before its termination,
the lymphatics of the left side of the head and neck, and of the left upper
extremity.
Structure. — The thoracic duct is composed of three coats, which differ in some
respects from those of the lymphatic vessels. The internal coat consists of a single
layer of flattened endothelial cells; of a subendothelial layer, similar to that found
in the arteries; and an elastic fibrous coat, the fibres of which run in a longitudinal
direction. Each endothelial cell is shaped like a lance-head and has serrated
LONGUS COLLI MUSCLE
COMMON CAROTID
ARTERY
LEFT VAGUS
NERVE
VERTEBRAL ARTERV
VERTEBRAL VEIN
THORACIC DUCT
INTERNAL JUGULAR
VEIN
EXTERNAL JUGULAR
VEIN
ANTERIOR JUGULAR
VEIN
SUBCLAVIAN
VEIN
FIG. 484. — The bend of the thoracic duct at its termination in the subclavian vein. (Poirier and Charpy.)
borders. The middle coat consists of a longitudinal layer of white connective
tissue with elastic fibres, external to which are several laminse of muscular
tissue, the fibres of which are for the most part disposed transversely, but some
are oblique or longitudinal. The muscular fibres are intermixed with elastic
fibres. The external coat is composed of areolar tissue, with elastic fibres and
isolated fasciculi of muscular fibres.
The Right Lymphatic Duct (Ductus Lymphaticus Dexter)
(Figs. 482, 485, 486, 509).
A right lymphatic duct is frequently present. It is a short trunk, about half an
inch in length and a line or a line and a half in diameter. It is formed by the union
of the right jugular, right broncho-mediastinal, and right subclavian trunks.
Often on the right side the jugular, subclavian, and broncho-mediastinal trunks
778
THE LYMPHATIC SYSTEM
are double. Usually they open into the junction of the internal jugular and
subclavian veins separately. Sometimes they unite and open by one duct, and
that is the right lymphatic duct. The orifice of the right lymphatic duct is
guarded by two semilunar valves, which prevent the passage of venous blood
into the duct.
Tributaries. — The right lymphatic duct, if present, receives lymph from the
right side of the head and neck, the right upper extremity, the right side of
the thorax, the right lung, and the right side of the heart, and from part of the
convex surface of the liver.
FIG. 485. — Terminal collecting trunks of the right half of the supra-diaphragmatic portion of the body. a.
jugular trunk; b, subclavian trunk; c, broncho-mediastinal trunk; d, right lymphatic trunk; e, gland of the
internal mammary chain; /, gland of the deep cervical chain. (Poirier and Charpy.)
LYMPHATICS OF THE CRANIAL REGION, FACE, AND NECK.
It is customary to divide the lymphatics of this region into intracranial and
extracranial lymphatics. The statement is made by Poirier and Cuneo1 that the
brain and its membranes are without lymphatics. They state that there are
spaces in the nervous centres comparable to lymphatic channels, but which are
not truly lymphatic vessels and which are regarded by most as independent of the
lymphatic system. Other writers believe that there are cerebral and meningeal
lymphatic vessels. It is highly probable that the perivascular spaces around the
cerebral arteries are the beginning of a cerebral lymph system, and that these peri-
vascular lymph-channels pass out of the cranium with the arteries and the internal
jugular vein and terminate in the superior deep cervical glands. It is also probable
that lymph-spaces surround the dural blood-vessels and terminate in the superior
deep cervical and the internal maxillary glands.
The extracranial lymphatics are divided into superficial and deep, and the two
systems freely communicate. All of these vessels run into glands about the
head and neck. The superficial lymphatics take origin in the subcutaneous
tissue and superficial muscles. The deep vessels arise in the orbit, mouth, nose,
pharynx, oesophagus, tongue, larynx, and the muscular, ligamentous, and osseous
structures.
The Lymphatic Glands of the Head and Face.
The lymphatic glands of the head and face are as follows:
1. The Occipital.
2. The Posterior Auricular.
3. The Parotid and Subparotid.
4. The Internal Maxillary.
5. The Facial.
1 Article on the Lymphatics in the Treatise on Human Anatomy. By Poirier and Charpy.
THE LYMPHATIC GLANDS OF THE HEAD AND FACE
779
The Occipital or Sub occipital Glands (lymphoglandulae occipitales) (Figs.
486 and 487). — There are only two or three of these glands on each side. They
arc situated beneath the deep fascia, a little in front of the anterior edge of the
FIG. 486. — The lymphatics of the head and neck. (Sappey.)
Trapezius muscle, near to but seldom upon the insertion of the Complexus
muscle. They receive lymph from the occipital region of the scalp and from
them it is sent to the upper deep cervical glands.
The Posterior Auricular Retro-auricular or Mastoid Glands (lymphoglandulae
auricular es posterior es) (Figs. 486, 487, and 491). — There are two of these on each
side. They are situated just beneath the lower margin of the Retrahens aurem
muscle. They receive lymph from the parietal lymph -vessels, "from the internal
surface of the auricle, with the exception of the lobule, and from the posterior
surface of the external auditory meatus."1 The lymph-vessels from these glands
empty into the upper deep cervical glands.
The Parotid Lymph-glands (lymphoglandulae auriculares anteriores) (Figs.
486, 487, and 488) are divided into two groups, the superficial and the deep.
The Superficial Parotid or Pre-auricular Lymph-glands. — The superficial parotid
lymph-glands are not the subcutaneous lymph-glands occasionally but very rarely
found in this region, and which have been described by Richet, but are lymph-
nodes situated between the parotid fascia and the parotid salivary gland. There
may be three glands, two glands, or only one gland.
1 The Lymphatics. By G. Delamare, P. Poirier, and B. Cuneb. English edition, translated and edited by
Cecil H. Leaf.
780
THE LYMPHATIC SYSTEM
The Deep Parotid Lymph-glands. — The deep parotid lymph-glands are situated
within the parotid salivary gland. There are from fifteen to twenty of the deep glands.
The parotid glands receive lymph from the eyelids, eyebrows, the root of the nose,
upper portion of the cheek, frontal portion of the scalp, temporal portion of the
FACIAL
SUBMAXILLARY
SUBMENTAL
FIG. 487. — General arrangement of the lymphatic gland groups of the head and neck. (Poirier and Charpy.)
GLANDS OF
EXTERNAL JUGULAR
CHAIN
SUBMAXILLARY
GLAND OF
INTERNAL JUGULAR
CHAIN
FIG. 488.— The lymphatics of the neck. (Kiittner.)
scalp, from the outer surface of the pinna, from the external auditory meatus,
from the tympanum, and possibly from the mucous membrane of the nose, the
THE LYMPHATIC GLANDS OF THE HEAD AND FACE 781
posterior alveolar region of the superior maxillary bone, and the soft palate.
Lymphatics pass from the superficial parotid glands into the superficial cervical
and the upper deep cervical glands. Lymphatics pass from the deep parotid
glands into the upper deep cervical glands.
The Subparotid Glands (lymphoglandulae parotidae). — The subparotid glands
lie between the parotid salivary gland and the pharyntf , and they are close to the
internal carotid artery and the internal jugular vein. They receive lymph from
the nasal fossae, naso-pharynx, and Eustachian tube, and send vessels to the upper
deep cervical glands.
SUBORBITAL
GLAND OF NASO-
GCNIAL GROOVE
BUCCINATOR
(posterior mass)
BUCCINATOR
(middle mass)
SUPRAMAXILLARY
INFRAMAXILLARV
FIG. 489. — Facial glands. (Poirier and Charpy.)
The Internal Maxillary or Zygomatic Glands (lymphoglandulae faciales pro-
fundae) (Fig. 486). — The internal maxillary glands lie in the course of the internal
maxillary artery in the anterior pharyngeal wall. They receive vessels from the
naso-pharynx, palate, zygomatic fossa, temporal fossa, and orbit. From them
vessels go to the upper deep cervical glands.
The Facial Glands or Genial Glands (lymphoglandulae faciales) (Figs. 487,
488, and 489). — The facial glands lie in three groups in the course of the lymphatic
vessels which are passing to the submaxillary glands. According to Poirier and
Cuneo the supramaxillary or inferior group (Fig. 489) lies upon the outer surface
of the mandible, at the anterior margin of the Masseter muscle, and beneath the
Platysma myoides. There may be only one or two glands in this group, but often
there are ten or twelve. These glands lie about the facial artery and vein and
are not constantly present. In many cases a salivary gland, the inframaxillary
(Fig. 489), is interposed between the supramaxillary and submaxillary glands.
The buccinator, buccal, or middle group (Figs. 486 and 489) is present in about
one-third of the subjects and lies upon the outer surface of the Buccinator muscle
external to the buccal fascia. Some of these glands are situated in the region
where Steno's duct perforates the Buccinator muscle. Others are beneath the
posterior fibres of the Zygomaticus major muscle.
The superior group of facial glands (Fig. 489) includes a malar gland, a suborbital
gland, and a gland in the naso-genial groove.1 An anterior gland is sometimes
found, subcutaneous, on the outer surface of the Orbicularis oris muscle, the
commissural gland.
The Lymphatic Vessels of the Cranial Region (Fig. 486).
The lymphatic vessels of the cranial subcutaneous tissues are divided into
anterior, lateral, and posterior. The anterior or frontal terminate in the parotid
» Article on the Lymphatics in the Treatise on Human Anatomy. By P. Poirier and B. Cune"o.
782
THE LYMPHATIC SYSTEM
lymph-glands. The lateral or parietal terminate in the parotid and mastoid lymph-
glands. The posterior or occipital terminate in the sterno-mastoid and occipital
glands.
The Lymphatic Vessels of the Face, the Interior of the Nose, Tongue,
Floor of the Mouth, Pharynx, Larynx, and Thyroid Gland
(Figs. 486, 488, 489, 490, 491, 492).
The lymphatic vessels of the face are more numerous than those of the cranial
region, and commence over its entire surface. Those from the frontal region
accompany the frontal vessels; they then pass obliquely across the face, running
with the facial vein, pass through the glands on the buccal surface of the Buccina-
tor muscle, and join the submaxillary lymphatic glands. The submaxillary lymph
glands receive the lymphatic vessels from the lips, and are often found enlarged
in cases of malignant disease of those parts.
The lymphatics of the orbit and of the temporal and zygomatic fossae run with
the branches of the internal maxillary artery to the maxillary glands, and after-
ward to the deep cervical glands.
VESSELS FROM
BASE OF TONGUE
MARGINAL COL-
LECTING TRUNKS
TRUNKS OF
PRINCIPAL
GLAND
W-SUBMENTAL
(TRUNKS OF
j MARGIN
FIG. 490. — The lymphatics of 'the tongue; anterior view. (Poirier and Charpy.)
The lymphatics of the nose can be injected from the subdural and subarachnoid
spaces. They terminate in the retro-pharyngeal and suprahyoid glands. The
lymphatics of the tongue (Fig. 490) chiefly accompany the ranine vein first to the
THE LYMPHATIC GLANDS OF THE NECK
783
lingual glands and from these to the deep cervical glands. The lymphatics from
the anterior part of the tongue and floor of the mouth pierce the Mylo-hyoid
muscles and so reach the submaxillary lymph-glands. From the upper part of
the pharynx the lymphatics pass to the retro-pharyngeal glands; from the lower
part of the pharynx to the deep cervical glands. From the larynx two sets of vessels
arise: an upper, piercing the thyro-hyoid membrane and joining the upper set
of deep cervical glands; and a lower, perforating the crico-thyroid membrane to
join the lower set of deep cervical glands. The lymphatics of the thyroid gland
accompany the superior and inferior thyroid arteries, and open partly into the
upper and partly into the lower set of deep cervical glands.
The Lymphatic Glands of the Neck.
The lymphatic glands of the neck are:
1. The Superficial Cervical, including the external jugular and the superficial
anterior cervical.
2. The Submaxillary.
3. The Submental.
4. The Retro-pharyngeal.
5. The Deep Cervical, including the anterior deep cervical.
The Superficial Cervical Glands (lymphoglandulae cervicales superficiales)
(Figs 486 and 491). — The superficial cervical glands are composed of two groups,
the external jugular and the superficial anterior cervical glands.
The External Jugular Glands (Figs. 488 and 491). — The external jugular glands
are superficial to the Sterno-cleido-mastoid muscle. They are four to six in
LYMPHATIC VESSELS
OF AURICLE
MASTOID GLANDS
STCRNO-MASTOIO
T~ GLAND (external
group)
GLAND OF
EXTERNAL JUGULAR
CHAIN
STERNO-MASTOID
GLAND (internal
group) .
SUBHYOID GLAND
FIG. 491.— Deep cervical chain. (Poirier and Charpy.)
number and lie along the external jugular vein upon the outer surface of the deep
cervical fascia, each gland occupying a depression in the fascia. The sterno-
cleido-mastoid muscle is beneath them. They are usually gathered in a group
a little below the parotid gland, but sometimes extend to the middle of the vein.
They receive vessels from the occipital, the posterior auricular, the parotid, and
the submaxillary lymph-glands, from the auricle, and from the skin and subcu-
taneous structures of the neck. From them lymphatic vessels pass to the upper
deep cervical and to the lower deep cervical glands.
784
THE LYMPHATIC SYSTEM
The Superficial Anterior Cervical Glands. — The superficial anterior cervical glands
lie along the anterior jugular vein and from them vessels pass to the deep cervical
glands.
The Submaxillary or Lateral Suprahyoid Glands (lymphoglandulae submaxil-
lares) (Figs. 486, 487, and 488). — The submaxillary glands are in the submaxil-
lary triangle beneath the deep fascia. They number three to six; are embedded
in the superficial surface of the sheath of the submaxillary gland, but are not found
within the sheath. Occasionally one or two are found in the deep portion of the
sheath toward the floor of the mouth. The middle gland of Stahr is situated at
the point where the submaxillary group is crossed by the facial artery. This is
the largest gland of the group. The submaxillary glands receive vessels from the
"nose, the cheek, the upper lip, and the external part of the lower lip, almost
the whole of the gums, and the anterior third of the lateral border of the tongue."1
They also obtain lymph from the floor of the mouth and from the sublingual and
submaxillary salivary glands. They send vessels to the jugular and to the upper
deep cervical glands.
The Submental or Median Suprahyoid Glands (Figs. 486, 487, and 490).—
There are usually two glands situated between the anterior bellies of the two
digastric muscles and upon the Mylo-hyoid muscle. They receive lymph from the
cutaneous surface of the chin, from the cutaneous and mucous surfaces of the
central portion of the lower lip, from the central portion of the gums, from the
floor of the mouth, and from the tip of the tongue. They send some vessels to
the submaxillary lymph-glands, and frequently a gland is interposed on the anterior
belly of the Digastric muscle. They send other vessels to the upper deep cervical
glands.
The Retro-pharyngeal or Post-pharyngeal Glands (Fig. 492). — The retro-
pharyngeal glands are placed between the upper lateral portion of the posterior
part of the pharynx and the first two cervical vertebrae. Leaf tells us that, as a
LYMPHATICS
OF PHARYNX
INTERRUPTING
GLANDULAR
NODULE
GLAND OF
DEEP CERVICAL
CHAIN
.EFFERENT
VESSEL OF
RETRO-PHARYNGEAL
GLANDS
FIG. 492. — The retro-pharyngeal glands. (Poirier and Charpy.)
rule, there is but one gland on each side, though two may be present. The retro-
pharyngeal glands lie upon the Rectus capitis anticus major muscle, which sepa-
rates them from the vertebra. They receive vessels from the muscles and fascia
in front of the vertebrae, from the nasal fossae and accessory cavities, from the naso-
i The Lymphatics. By G. Delamare, P. Poirier, and B. Cunte. Translated and edited by Cecil H. Leaf.
THE LYMPHATIC GLANDS OF THE NECK 7Sf>
pharynx and Eustachian tube, and possibly from the cavity of the tympanum.
They send vessels to the upper deep cervical glands.
The Deep Cervical, Carotid, or Sterno-mastoid Glands (lymphoglandulae
cervicales profundae) (Figs. 486, 487, 488, 490, 491, and 492).— The deep cervical
glands are divided into the upper deep cervical and the lower deep cervical, and are
associated with certain accessory glands, including the jugular and superficial anterior
cervical, which have been discussed under the head of superficial cervical glands;
and the anterior deep cervical and the recurrent glands, which have not yet been
studied. The deep cervical chain extends from the apex of the mastoid process
of the temporal bone to the junction of the internal jugular and subclavian veins.
The Upper Deep Cervical or Substemo -mastoid Glands (lymphoglandulae cervi-
cales profundae superiores). — The upper deep cervical glands extend from the
tip of the mastoid process of the temporal bone to about the region where the
common carotid artery is crossed by the Omo-hyoid muscle. One group,
the external group, is placed external and posterior to the internal jugular vein.
The glands are small and numerous, are embedded in the fatty tissue about the
nerves from the deep cervical plexus, and at the posterior margin of the Sterno-
cleido-mastoid muscle constitute a continuous mass passing to join the subclavian
glands. Another group, known as the internal group or the internal jugular
glands, lie directly upon or close by the outer border of the internal jugular vein.
This group forms a chain along the internal jugular vein, and the glands are
of larger size than those of the external group. Some glands of this group
are beneath the vein. The glands of the internal jugular group communicate
freely with each other and with the external group. The external group receives
lymph-vessels from the posterior auricular, occipital, and external jugular glands,
from the occipital region of the scalp, from the auricle, and from the skin, sub-
cutaneous tissue, and muscles of the upper portion of the neck.1 The internal
group receives lymph-vessels from the retro-pharyngeal, parotid, subparotid, sub-
maxillary, and submental glands, the anterior cervical glands (superficial and
deep), and the recurrent glands, and from the tongue, naso-pharynx, larynx, soft
palate, roof of the mouth, oesophagus (cervical portion), nasal fossse, trachea
(cervical portion), and the thyroid gland.2 The external group terminates in
the supraclavicular glands. The internal jugular group terminates in the
jugular trunk, which, on the right side, helps to form the right lymphatic duct
or empties directly into the junction of the internal jugular and subclavian veins,
and on the left side empties directly into the venous junction or into the thoracic
duct.
The Lower Deep Cervical or Supraclavicular Glands (lymphoglandulae cervicales
profundae inferior es). — The lower deep cervical glands lie along the internal
jugular vein in the lower part of its course. They receive lymph- vessels
from the superficial cervical glands, the upper deep cervical glands, the
axillary glands, the accessory chain, the occipital region of the scalp, the skin of
the neck, the lower prevertebral muscles, the skin of the pectoral and mammary
regions, and the skin of the arm. The supraclavicular glands send vessels which
unite with the vessels of the upper deep glands to form the jugular lymphatic
trunk. The jugular trunk on the right side may empty directly into the junc-
tion of the internal jugular and subclavian veins or may unite with the subclavian
trunk to form the right lymphatic duct. On the left side it may empty into the
thoracic duct or directly into the venous junction.
Accessory Chains to the Deep Cervical Glands. — The accessory chains to the deep
cervical glands are : 1. The external jugular glands (p. 783). 2. The superficial
anterior cervical (p. 784). 3. The prelaryngeal or infralaryngeal glands (Fig. 486)
1 The Lymphatics. By G. Delamare, P. Poirier, and B. Cun6o. Translated and edited by Cecil H. Leaf.
2 Ibid.
50
786 THE LYMPHATIC SYSTEM
between the Crico-thyroid muscles. They receive lymph from the trachea, larynx,
and thyroid gland, and send vessels to the pretracheal glands and to the upper
deep cervical glands. 4. The trachea! or pretracheal glands (Fig. 486) lie upon the
front of the trachea, receive vessels from the trachea, thyroid body, and prelaryngeal
glands, and send vessels to the lower deep cervical glands. Some anatomists speak
of the prelaryngeal and the pretracheal glands as the anterior deep cervical glands.
5. The recurrent glands lie on the sides of the oesophagus and trachea, by the recur-
rent laryngeal nerves. They receive vessels from the larynx, trachea, resophagus,
and thyroid gland, and send vessels to the upper and lower deep cervical glands.
The Lymphatic Vessels of the Neck (Figs. 486,490,491).
The superficial and deep cervical lymphatic vessels are continuations of those
already described on the cranium and face. After traversing the glands in those
regions, they pass through the chain of glands which lie along the sheath of the
carotid vessels, being joined by the lymphatics from the pharynx, resophagus,
larynx, trachea, and thyroid gland. At the lower part of the neck, after receiving
some lymphatics from the thorax, they unite to form the jugular trunk (Fig. 485),
which often terminates, on the left side, in the thoracic duct, and on the right side,
in the right lymphatic duct, but which may on either side open directly into the vein.
Surgical Anatomy. — In secondary syphilis there is general enlargement of the lymphatic
glands, and in the posterior triangle of the neck the enlarged glands are distinctly palpable. The
occipital glands may enlarge because of inflammation or suppuration about the occipital region
of the scalp, and the posterior-auricular glands enlarge from inflammation or suppuration of the
temporal portion of the scalp, the external ear (except the lobule), and the external auditory meatus.
Otorrhcea sometimes causes them to enlarge.
The cervical glands are very frequently the seat of tuberculous disease. This condition is
usually preceded by a lesion in those parts from which they receive their lymph. The lesion may
be tuberculous or inflammatory. If tuberculous it furnishes bacilli directly to the lymph. If
inflammatory it lessens tissue resistance and opens the portals to infection. The glands receive
the lymph from the seat of primary disease and become tuberculous. It is very desirable, there-
fore, for the surgeon, in dealing with these cases, to possess a knowledge of the relation of the
respective groups of glands to the periphery. Some years ago Sir Frederick Treves prepared a
table to show to what glandular group lymph from each region is sent. The table is practically
as follows:
Scalp. — Posterior part = suboccipital and mastoid glands. Frontal and parietal portions =
parotid glands.
Lymphatic vessels from the scalp also enter the superficial cervical set of glands.
Skin of face and neck — submaxillary, parotid, and superficial cervical glands.
External ear = superficial cervical glands.
Lower lip = submaxillary and suprahyoid glands.
Buccal cavity —- submaxillary and upper set of deep cervical glands.
Gums of lower jaw = submaxillary glands.
Tongue. — Anterior portion = suprahyoid and submaxillary glands. Posterior portion =
upper set of deep cervical glands.
Tonsils and palate = upper set of deep cervical glands.
Pharynx. — Upper part = parotid and retro-pharyngeal glands. Lower part = upper set of
deep cervical glands.
Larynx, orbit, and roof of mouth = upper set of deep cervical glands.
Nasal fossv = retropharyngeal glands, upper set of deep cervical glands. Some 'lymphatic
vessels from posterior part of the fossse enter the parotid glands.
' Treves's table indicates the glands usually involved, but the seat of primary disease cannot in-
variably be affirmed from a knowledge of the seat of glandular involvement, because the course
of the lymphatic vessels is sometimes varied from that which usually maintains ; for instance, in
some cases lymphatics from the right side of the tongue pass to glands in the left side of the
neck.
Glands may enlarge directly because of primary inflammation, injury, or tumor, but usually
a glandular enlargement is secondary to a bacterial disease or to cancer involving the lymph-
vessels which come to the gland. The seat of disease may be distant. Disease of the nasal
fossae may cause retropharyngeal abscess or enlargement of the submaxillary glands. Cancer
of the breast, stomach, or oesophagus may be followed by disease of the cervical glands. Dis-
THE LYMPHATIC GLANDS OF THE UPPER EXTREMITY 787
ease of the teeth, tongue, gums, floor of the mouth, and alveolar processes may cause enlarge-
ment of the submaxillary and other glands, and disease of the tonsil may lead to enlargement
of the glands at the angle of the jaw.
The modern radical surgery of cancer depends on a knowledge of these glandular relations,
and consists in thoroughly removing the growth and also the associated lymphatic glands, and,
when possible, the lymph-vessels running from the tumor to the glands. The lower deep cer-
vical glands occasionally enlarge secondarily to malignant growths of the abdomen or medias-
tinum, but this is not due to a direct flow of lymph, as the mediastinal glands do not send ves-
sels to the supraclavicular glands. It is due to blocking of lymphatic vessels and reversal of
the lymph-stream, so that lymph containing cancerous cells regurgitates.
A retropharyngeal abscess begins to the side of the pharynx. It enlarges toward the centre
rather than from it, because the constrictions of the pharynx limit the outward progress of the
pus.
The glands within the parotid salivary gland not unusually become tuberculous, and the
• surgeon may be led to believe that the salivary gland is the seat of primary disease.
Sometimes, though seldom, after the extensive removal of lymph-glands the region drained
by their tributaries becomes the seat of persistent hard cedema (lymph oedema). It used to be
thought that wounds of the thoracic duct were of necessity fatal, but it is now known that, unless
close to the vein, they are seldom even very dangerous. It may be possible to suture a partly
divided duct.1 In an unsutured wound of the duct recovery follows if a collateral lymphatic
circulation is established.2
THE LYMPHATICS OF THE UPPER EXTREMITY.
The Lymphatic Glands of the Upper Extremity.
The lymphatic glands of the upper extremity are divided into two sets, super-
ficial and deep.
Superficial Lymphatic Glands (Figs. 493 and 501). — The superficial lymphatic
glands of the upper extremity are few in number and small in size. They lie in the
subcutaneous tissue. They are not receiving depots of great areas, but interrupt
lymphatic vessels here and there. The glands in the axilla receive all of the
lymphatic vessels, superficial and deep. There may be three sets of superficial
glands.
One set, the ante-cubital glands, lies in front of the elbow. These glands are
often absent. When these glands are present they receive vessels from the anterior
portion of the forearm and the middle of the palm. The vessels from them pass
upward along the front and inner aspect of the arm.
Another superficial gland lies above the internal condyle. It is the supratrochlear
or supraepitrochlear gland or group of glands. There is usually but one gland, but
there may be two or more. It receives vessels from the inner portion of the hand,
the three inner fingers-, and the inner portion of the forearm, but, because of free
anastomoses, also may receive lymph from any portion of the hand and forearm.
Lymph-vessels from the supratrochlear gland pass up along the basilic vein to
the axillary glands.
There are sometimes several small glands by the cephalic vein in the groove
between the Deltoid and great Pectoral muscles. These are called infraclavicular
glands. The lymph-tract from the infraclavicular glands does not terminate in
the axillary glands, but ends in the subclavian glands.
The Deep Lymphatic Glands of the Upper Extremity or the Axillary Glands
(lymphoglandulae axillares] (Figs. 493, 494, 495, 496, and 501). — The chief deep
glands are situated adjacent to the axillary vessels. There are also a few small
glands along the radial, ulnar, and brachial arteries which receive deep lymphatics
from bones, muscles, and ligaments, and send lymphatics to the axillary glands.
The axillary glands number from fifteen to thirty-five in each axilla. They are
embedded in the axillary fat and receive the lymphatic vessels from the upper
1 Dudley P. Allen's case. See Allen arid Brings, in American Medicine, September 21, 1901.
2 Harvey Gushing, Annals of Surgery, June, 1898.
788
THE LYMPHATIC SYSTEM
extremity, from the skin of the upper portion of the chest, from the Pectoral
muscles, and from the mammary gland. The following division of the axillary
glands is made by Poirier, Cuneo, and Delamare:1 1. An external group, the
Axillary glands.
FIG. 493. — The superficial lymphatics and glands of the upper extremity.
humeral chain, lying on the inner surface of the vessels and nerves, particularly the
axillary vein, to the sheath of which they are adherent. Occasionally one or several
of these glands are found beneath the vein. Some of the vessels from these glands
pass into the central group of lymph-nodes; others enter the subclavian glands;
others pass above the clavicle and terminate in glands situated in that region. 2.
An anterior group, the thoracic chain, called also the pectoral glands (lymphoglandulae
pectorales) . One mass of this chain, the supero-internal, is situated in the second or
third intercostal space in front of the long thoracic artery and beneath the lower
edge of the great Pectoral muscle. Another mass, the infero-external, is situated in
the fourth and fifth intercostal spaces along the course of the long thoracic artery.
The vessels from this chain end in the central group, and some few of them in the
subclavian glands. 3. A posterior group, the scapular chain, lying along the dorsali?
1 The Lymphatics. Translated and edited by Cecil H. Leaf.
THE LYMPHATIC GLANDS OF THE UPPER EXTREMITY 789
scapulae artery in the groove between the Teres major and the Subscapularis
muscles. They send vessels to the humeral and central chains. 4. A central
DELTA-PECTORAL HUMERAL CHAIN
HUMERAL
CENTRAL-
GROUP
SCAPULAR
CHAIN
MAMMARY LYMPHATIC
ENDING IN SUB-
CLAVIAN GLANDS
THORACIC
CHAIN
MAMMARY COL-
LECTING TRUNKS
3 SUBAREOLAR
PLEXUS
THORACIC
CHAIN
CUTANEOUS COLLECTING
TRUNK FROM THE
THORACIC WALL
CUTANEOUS COL- "\ -\V_ COLLECT! NG TRUN KS
LECTING TRUNKS PASSI NG TO I NTE RNAL
MAMMARY GLANDS
i-io. 494.— Axillary glands and lymphatics of the breast. (Poirier and Charpy.)
FIG. 495.— Lymphatics of the antero-lateral portion of the thorax. (Sappey.)
790 THE LYMPHATIC SYSTEM
group, the intermediate glands, placed near the base of the axilla, between the pre-
viously described chains. Their efferent vessels end in the subclavian glands. The
glands of the central group in many individuals protrude through the opening in the
axillary fascia known as the foramen of Langer (Fig. 312). 5. A subclavian group,
situated above the upper margin of the lesser Pectoral muscle. Most of them are
internal to the axillary vein, "between this vein and the first digitation of the
Serratus magnus."1 The humeral chain and the thoracic chain come together and
form the subclavian group of glands situated at the apex of the axilla. From the
axillary glands come many vessels which, by anastomosing, form the infraclavic-
ular plexus, they then unite into a trunk, the subclavian trunk, which courses
between the subclavian vein and Subclavius muscle. On the right side it empties
into the junction of the internal jugular and subclavian vein or unites with the
jugular trunk to form the right lymphatic duct. On the left side it may empty into
the venous junction or into the thoracic duct.
SUPRA
CLAVICULAR
LINE OFTHE
CLAVICLE
SUBCLAVIAN
-CENTRAL GROUP
HUMERAL-
SCAPULAR
CHAIN
SUPEHO-INTERNAL
PORTION OF
THORACIC CHAIN
INFCRO-EXTEHNAL
PORTION OF
THORACIC CHAIN
FIG. 496. — Scheme of the axillary glands. The dotted line indicates the position of the clavicle.
(Poirier and Charpy.)
The Lymphatic Vessels of the Upper Extremity (Figs. 493, 494, 495, 496, 497).
The lymphatic vessels of the upper extremity are divided into the superficial
and the deep.
The Superficial Lymphatic Vessels of the Upper Extremity.— The superficial
vessels begin as plexuses in the skin and form vessels which ascend in the sub-
cutaneous tissue. These plexuses are particularly plentiful in the palm and
palmar surface of the digits (Fig. 497). On each side of each finger two lymph-
vessels are formed; they ascend toward the hand, cross the dorsum, and anas-
tomose frequently with each other. The vessels from the dorsum of the hand
join the lymph-vessels of the forearm, which ascend chiefly along the superficial
veins. The lymph-vessels which ascend with the superficial ulnar vein pass into
the supratrochlear gland. The vessels which accompany the median veins pass
into the ante-cubital or supratrochlear glands. Some of the lymph-vessels on
the radial side of the forearm run up along the cephalic vein. All the other
lymph-vessels of the upper extremity pass direct to the axillary glands. In the
forearm there are about thirty vessels, in the middle of the arm there are from
fifteen to eighteen (Sappey).
The Deep Lymphatic Vessels of the Upper Extremity.— The deep lymph-
vessels convey the lymph from bone, periosteum, muscle, ligament, etc. They pass
up the limb with the chief vessels, there usually being two trunks to each artery.
1 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf.
THE LYMPHATIC GLANDS OF THE LOWER EXTREMITY 791
In the arm there are two or three vessels. Some few vessels terminate in the
small glands along the radial, ulnar, and brachial arteries, but most of them pass
directly to the axillary glands.
Surgical Anatomy. — In malignant dis-
eases, or other affections implicating the
upper part of the back and shoulder, the
front of the chest and mamma, the upper
part of the front and side of the abdomen,
or the hand, forearm, or arm, the axillary
glands are liable to be found enlarged.
In secondary syphilis the supratrochlear
gland is found to be enlarged. This gland
is subcutaneous and readily palpable when
enlarged. Normal axillary glands cannot
be palpated. The axilla is a passage-way
for structures between the neck and the
upper extremity, and purulent collections
or tumors may extend from the neck into
the axilla or from the axilla into the neck.
The axillary glands are involved early in
cases of cancer of the mammary gland, and
later the lower deep cervical glands are
involved, and, as Snow has pointed out,
regurgitation of lymph-containing cancer
cells leads to retrosternal involvement and
to secondary cancer of the head of the
humerus. In operating for cancer of the
breast, follow the principle of Halsted and
remove the breast, the skin over it, the
muscles and fascia, the lymph-vessels, and
the axillary glands in one piece. By this
plan thorough removal is possible, and as
lymph-vessels containing carcinoma cells
are not cut across, the wound is not grafted
with malignant epithelial cells. Diseased
axillary glands are apt to adhere to the
sheath of the vein. In removing cancerous
glands, always excise the sheath of the vein.
FIG. 497. — Lymphatic vessels of the dorsal surface of
the hand. (Sappey.)
THE LYMPHATICS OF THE LOWER EXTREMITY.
The Lymphatic Glands of the Lower Extremity.
The lymphatic glands of the lower extremity are divided into two sets, super-
ficial and deep. The superficial are confined to the inguinal region, forming the
superficial inguinal lymphatic glands.
The Superficial Inguinal Lymphatic Glands (lymphoglandulae inguinales
superficiales) (Figs. 498, 499, 500, and 501). — The superficial inguinal lymphatic-
glands, placed immediately beneath the integument in Scarpa's triangle, are of
large size, and vary in number from ten to twenty. It is customary to divide
these glands into groups according to the region in which they are found. The
following division is suggested by Poirier, Cuneo, and Delamare:1 A horizontal
line carried through the saphenous opening divides the glands into two groups,
a superior group and an inferior group. A vertical line through the saphenous
opening divides each of the two groups into two secondary groups, an external and
an internal group. We thus have an external and superior group, and internal and
superior group, an external and inferior group, and an internal and inferior group.
1 The Lymphatics. Translated and edited by Cecil H. Leaf.
792
Directly in the saphenous opening there are often several glands constituting a
central group.
SUPERIOR
EXTERNAL
GROUP
SUPERIOR
INTERNAL
GROUP
INFERIOR
INTERNAL
GROUP
INFERIOR
EXTERNAL
GROUP
FIG. 498. — Superficial inguinal glands. Cribriform fascia has been removed so as to expose the femoral
vessels. (Poirier and Charpy.)
FIG. 499. — Glands of the inguinal region with the afferent and efferent lymphatics. (Poirier and Charpy.)
Leaf points out that a gland usually exists near the saphenous opening, which
is interposed between the superficial inguinal and deep inguinal glands. The
superior group of glands, sometimes called the oblique group, is so placed that the
////; LYMPHATIC GLANDS OF Til H LOWER EXTREMITY 793
Superficial
iiitiniiial
glands.
glands lie with a certain regularity along
and below Poupart's ligament, the long
axis of each gland corresponding with
the direction of the ligament. It is now
known that each group of the superficial
glands does not receive with regularity
the lymph from and only from a definite
and accurately determined area. Hence,
it is not possible, as was once taught, to
determine with certainty the exact situa-
tion of a lesion by the group of superficial
glands involved. The superficial inguinal
-* — «^~
FIG. 500. — The superficial lymphatics and glands
of the lower extremity.
FIG. 501. — Superficial lymphatic vessels of the lower
extremity, exterior surfaee. (Sappey.)
794 THE LYMPHATIC SYSTEM
glands receive vessels from the skin of the lower extremity, gluteal region, peri-
neum, abdominal wall, scrotum, anus, and from the prepuce of the clitoris and
penis. Occasionally, though not normally, they receive vessels from the glans
penis and glans clitoris. The superficial glands send vessels to the deep inguinal
glands and to the external iliac glands, and these vessels penetrate the femoral
sheath. The vessels which go to the iliac glands ascend with the femoral vessels.
Leaf figures some of the efferent vessels from these glands as terminating directlv
in the veins of this region.
Surgical Anatomy. — The superficial inguinal glands frequently become enlarged in diseases
implicating the parts from which their lymphatics originate. Thus, in malignant or syphilitic
affections of the prepuce and penis, or of the labia majora in the female, in cancer scroti, in
abscess in the perineum, and in other diseases affecting the integument and superficial structures
in those parts, or the subumbilical part of the abdominal wall or the gluteal region, the upper
chain of glands is almost invariably enlarged, the lower chain being implicated in diseases affect-
ing the lower limb.
The Deep Lymphatic Glands of the Lower Extremity.— The deep glands
are the inguinal, anterior tibial, popliteal, gluteal, and ischiatic.
The Deep Inguinal or Deep Femoral Lymphatic Glands (lymphoglandulae ingui-
nales profundae). — The deep inguinal lymphatic glands are beneath the deep
fascia. There are only two or three of them, and they lie to the inner side of
the femoral vein, the upper gland being in the crural canal and projecting into
the pelvis. It is called the gland of Cloquet or the gland of Rosenmiiller. The
deep inguinal glands receive vessels from the superficial inguinal glands, deep
lymphatics from along the femoral vessels, and vessels from the glans penis or
clitoris. They send vessels to the ilio-pelvic glands.
The Anterior Tibial Gland (lymphoglandula tibialis anierior). — The anterior
tibial gland is not constant in its existence. It is generally found by the side of
the anterior tibial artery, upon the interosseous membrane at the upper part of
the leg. Occasionally two glands are found in this situation. It receives a deep
anterior tibial lymphatic trunk and sends off a vessel to the popliteal glands.
The Popliteal Glands (lymphoglandulae popliteae). — The popliteal glands are
embedded in the cellular tissue and fat of the popliteal space and about the pero-
neal vessels. The juxta-articular gland receives lymph-vessels from the knee-joint.
The popliteal glands send vessels to the superficial and deep inguinal glands.
The popliteal glands are divided into three groups :2 1. A gland external to the
termination of the external saphenous vein, the external saphenous gland. 2. A
middle group of three or four glands on the sides of the popliteal vessels. The
inferior glands of this group are the intercondyloid glands of Leaf. The superior
glands are the supracondyloid glands of Leaf. 3. A gland adherent to the posterior
ligament of the knee-joint, the juxta-articular gland of Poirier and Cuneo. The ex-
ternal saphenous gland receives vessels which ascend along the external saphenous
vein. The middle group receives vessels from the anterior tibial glands and deep
lymphatic vessels which ascend with the posterior tibial.
The Gluteal and Ischiatic Glands. — The gluteal and ischiatic glands are placed,
the former above, the latter below, the Pyriformis muscle, resting on their corre-
sponding blood-vessels as they pass through the great sacro-sciatic foramen.
The Lymphatic Vessels of the Lower Extremity (Figs. 500, 501).
The lymphatic vessels of the lower extremity, like the veins, may be divided
into two sets, superficial and deep.
• The Surgical Anatomy of the Lymphatic Glands, 1898.
2 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leat.
THE ILIAC OR ILIO-PELVIC GLANDS 795
The Superficial Lymphatic Vessels of the Lower Extremity. — The superficial
lymphatic vessels are placed beneath the integument in the superficial fascia, and
are divisible into three sets: trunks which follow the course of the internal
saphenous vein, trunks which accompany the external saphenous vein, and
trunks from the gluteal region. 1. Trunks which follow the course of the
internal saphenous vein arise from a plexus on the dorsum of the foot, which
plexus obtains lymphatics from all the toes, the sole, and both borders of the foot.
The internal trunks, three or four in number, pass to the superficial inguinal
glands. Theexternal trunks run upward and inward and end in the internal trunks.
2. The trunks which follow the external saphenous vein number two or three, and
they take origin from the heel and from the posterior half of the outer edge of
the foot. They empty into the superficial inguinal glands. 3. The lymph-trunks
from the gluteal region join vessels from the anus and enter the superficial
inguinal glands.
The Deep Lymphatic Vessels of the Lower Extremity. — The deep lymphatic
vessels of the lower extremity are few in number and accompany the deep blood-
vessels. In the leg they consist of three sets, the anterior tibial, peroneal, and
posterior tibial, which accompany the corresponding blood-vessels, two or three
to each artery; they ascend with the blood-vessels and enter the lymphatic glands
in the popliteal space; the efferent vessels from these glands accompany the femoral
vein and join the deep inguinal glands; from these glands vessels pass beneath Pou-
part's ligament and communicate with the chain of glands surrounding the exter-
nal iliac vessels. The deep lymphatic vessels of the gluteal and ischiatic regions
follow the course of the blood-vessels, and join the gluteal and ischiatic glands at
the great sacro-sciatic foramen.
THE LYMPHATICS OF THE PELVIS AND ABDOMEN.
The lymphatics of the pelvis and abdomen constitute a continuous chain, but
for convenience of study it is customary to divide them into two groups, which
we call, with Poirier and Cune'o,1 the ilio-pelvic glands and the abdomino-aortic
glands; the first group being below and the second above the level of the bifurca-
tion of the aorta into the two common iliac arteries.
The Iliac or Ilio-pelvic Glands (Lymphoglandulae Iliacae) (Figs. 502, 503).
The ilio-pelvic glands are at the level of the inlet of or in the cavity of the
pelvis. They follow the course of the blood-vessels and are divisible into the
external iliac, the internal iliac, and the common iliac chains.
The External Hiac Glands. — The external iliac glands form chains around
the external iliac vessels. There are three chains of these glands. An external
chain of three or four glands lies between the artery and the Psoas muscle.
The lowest gland of the external chain is called by Poirier and Cune'o the external
retro-crural gland (Fig. 502). A middle chain of three glands lies upon the front
surface of the external iliac vein. The lowest gland of this group is called by
Poirier and Cune'o the middle retro-crural gland. An internal chain of three or
four glands is placed to the inner side of the external iliac vein. The lowest gland
of this chain is called the internal retro-crural gland, and is close to the upper gland
of the deep inguinal chain, the gland of Cloquet. The obturator gland belongs to
the inner chain of external iliac glands. The external iliac glands receive vessels
from the superficial and deep iliac glands, from the glans penis or glans clitoris,
deep lymphatics from the umbilicus and lower part of the belly wall, vessels from the
superior portion of the vagina, the uterine neck, the prostate gland, the bladder,
1 Treatise on Human Anatomy.
796
THE LYMPHATIC SYSTEM
the membranous portion of the urethra, and the internal iliac glands, and the
obturator gland receives deep lymph-vessels from along the course of the obtu-
rator vessels. The external iliac glands send vessels direct to the common iliac
glands and also lymphatics to join vessels from the internal iliac glands on their
way to the common iliac group. The glands along the deep epigastric artery
and those along the deep circumflex iliac artery are accessory chains to the main
group of external iliac glands.
RIGHT JUXTA
AORTIC
LEFT JUXTA
AORTIC
COMMON
ILIAC
PROMONTORY —
COMMON ILIAC
(middle group) —
EXTERNAL ILIAC
(external chain)
OBTURATOR
ARTERY
IIP
FIG. 502. — Ilio-pelvic glands. (Poirier and Charpy.)
The Internal Iliac or Hypogastric Glands (lymphoglandulae hypogastricae).—
The internal iliac glands are placed along the internal iliac artery and its branches.
The gland on the middle hemorrhoidal artery is called the middle hemorrhoidal
gland. The lateral sacral gland is on the lateral sacral artery. The internal iliac
glands receive lymph from the pelvic viscera, perineum, and penile portion of the
urethra, deep tissues of the posterior portion of the thigh, and from the buttocks.
They send vessels to the common iliac glands and also to the external iliac glands.
The Common Hiac Glands, — The common iliac glands are found about the
common iliac artery and are divided into an external group, which lies upon the
inner edge of the Psoas muscle; a middle group, behind the artery, and an internal
group, which lies upon the front of the body of the fifth lumbar vertebra or upon
the sacro-vertebral junction. They receive vessels from the external and internal
THE ABDOMINO-AORTIC GLANDS
797
iliac glands and from the pelvic viscera, the vessels from the pelvic viscera ascend-
ing to the promontory of the sacrum and containing perhaps, here and there,
interrupting glands, known as sacral glands (lymphoglandulae sacrales} (Fig. 509).
They also receive lymph-vessels from the lumbo-sacral region. They send vessels
to the aortic glands. Some anatomists place the common iliac glands and the
glands about the lower portion of the aorta and vena cava in a group called the
lumbar glands (lymphoglandulae lumbales] (Fig. 509).
INTCRPCLVIC
GLUTEAL
PROMONTORY
EXTERNAL ILIAC
(middle chain)
EXTERNAL ILIAC
(middle chain)
EXTERNAL ILIAC
(external chain)
RETROCRURAL
EXTERNAL
RETROCRURAL
INTERNAL
LYMPHATICS
OF BLADDER
LYMPHATIC FROM
CLANS PENIS
LYMPHATICS
OF BLADDER
LATERAL
SACRAL
HYPOGASTRIC
HYPOGASTRIC
SATELLITE TRUNK
OF INTERNAL
PUDIC VESSELS
TRUNK OF
MIDDLE HEMOR-
RHOIDAL VESSELS
PROSTATIC COL-
LECTING TRUNK
URETHRAL COL-
LECTING TRUNKS
LYMPHATIC GLANDULAR NODULE
IN FRONT OF SYMPHYSIS
PROSTATIC COL-
LECTING TRUNK
FIG. 503. — The Ilio-pelvic glands (lateral view). (Poirier and Charpy.)
The Abdomino-aortic Glands (Figs. 483, 509).
The abdomino-aortic glands are placed about the abdominal aorta. There are
twenty-five or thirty of them. They are divided by Poirier, Cune'o, and Delamare1
into the right and left juxta-aortic glands, the retro-aortic glands, and the pre-aortic
glands.
The Right Juxta-aortic Glands. — The right juxta-aortic glands are grouped
in front of and behind the postcava, the posterior glands lying upon the Psoas
muscle and the adjacent pillar of the Diaphragm. They receive lymph-vessels
from the right common iliac glands, from the right testicle or the right half of
the uterus, and the right tube, ovary, broad ligament, the right kidney and supra-
renal capsule, and also lymph-vessels which pass along the lumbar arteries.
They send vessels to the pre-aortic and the retro-aortic glands and the receptaculum
chyli.
i The Lymphatics. Translated and edited by Cecil H. Leaf.
798 THE L YMPHA TIC SYSTEM
The Left Juxta-aortic Glands.— The left juxta-aortic glands lie by the side of
the abdominal aorta, upon the Psoas muscle, and the left pillar of the Diaphragm.
They receive tributaries from the left side corresponding to those received by
the glands of the right side, and also send out corresponding efferent vessels, and
several additional vessels which pass through the left pillar of the Diaphragm and
empty into the thoracic duct.
The Retro-aortic Glands. — The retro-aortic glands are placed beneath the
receptaculum chyli and in front of the bodies of the fourth and fifth lumbar ver-
tebne. They receive lymph-vessels from both juxta-aortic groups, and also from
the pre-aortic glands, and they send vessels to the receptaculum chyli.
The Pre-aortic Glands. — The pre-aortic glands lie upon the front of the aorta,
and in most subjects are divisible into three groups : an inferior, lying at the origin
of the inferior mesenteric artery; a middle, at the origin of the superior mesenteric
artery, and a superior, about the coeliac axis, the coeliac glands (lymphoglandulae
coeliacae). Glands which are found along the course of all the branches of the
abdominal aorta empty into and belong to the group of pre-aortic glands. The
pre-aortic glands receive vessels from the juxta-aortic glands and from all the
glands along the mesenteric vessels and the coeliac axis and its branches,
and receive lymph from the stomach, intestines, liver, pancreas, and spleen.
They anastomose with each other and send vessels to the retro-aortic glands and
to the receptaculum chyli. Instead of the glands terminating in the receptaculum
by separate vessels, the vessels may unite and form a common trunk, the intes-
tinal trunk (truncus intestinalis] , which runs along with the common trunk from
the juxta-aortic glands, and empties into the receptaculum (Fig. 483).
1. The Glands along the Mesenteric Arteries (lymphoglandulae mesentericae] receive
the lymph from the colon, caecum, appendix, ileum, jejunum, duodenum, and
perhaps also some from the stomach.
2. The Glands Connected with the Cceliac Axis and its Branches. — There are three
groups of these glands: the gastric or coronary, the splenic, and the hepatic (in-
cluding those of the bile-ducts).
The Gastric Glands (lymphoglandulae gastricae). — One group is situated in the
gastro-pancreatic fold ; another group is connected with the lesser curvature of the
stomach (Fig. 506). Some of them are in the lesser omentum close to insertion of
the thicker part upon the stomach, and lie near the ascending branches of the gastric
artery, that is to say, upon the vertical portion of the lesser curvature. Others lie
within the lesser omentum and accompany the descending branches of the gas-
tric artery, and particularly gather near the point where the gastric artery comes
toward the stomach wall. The gastric glands receive lymph from most of the
stomach. They send lymph to the upper group of pre-aortic glands, the coeliac
glands.
The Splenic Glands (lymphoglandulae pancreaticolienales) . — The splenic glands
accompany the splenic artery and lie upon the posterior surface of the spleen,
between the spleen and pancreas. They receive lymph from the fundus of the
stomach, from the spleen, and from the pancreas, and send it to the coeliac glands.
The Hepatic Glands (lymphoglandulae hepaticae). — These glands lie along the
hepatic artery, some on the level of the floor of the foramen of Winslow, others by
the left side of the portal vein.1 The authors previously quoted point out that there
is a secondary chain of hepatic glands about the right gastro-epiploic artery, the
gastro-epiploic chain, and that this comprises a subpyloric group and a retro-pyloric
group. The subpyloric group (Fig. 506) is placed in the great omentum below the
pylorus, and is usually distinctly separated from it. -The retro-pyloric group is not
constant. It is placed along the gastro-duodenalis artery back of the pylorus.
There is also a group of glands, secondary to the hepatic glands, to the right of
1 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf.
THE LYMPHATIC VESSELS OF THE ABDOMEN AND PELVIS 799
or posterior to the cystic duct and the common bile-ducts. The hepatic glands
proper receive lymph from the liver and send it to the co?liac glands. The
subpyloric glands receive lymph from the inferior portion of the stomach and
from the superior portion of the great omentum. They send lymph to the hepatic
glands proper, the retro-pyloric glands, and sometimes also to the glands about
the superior mesenteric artery. The retro-pyloric glands receive lymph from the
subpyloric glands, from the upper surface and from the posterior surface of
the pylorus, and from the duodenum. They send lymph to the hepatic glands
proper and sometimes to the glands along the superior mesenteric artery. The
glands along the gall-ducts empty into the hepatic glands proper.
The Lymphatic Vessels of the Abdomen and Pelvis.
The lymphatic vessels of the abdomen and pelvis may be divided into two sets,
superficial and deep.
The Superficial Lymphatic Vessels of the Walls of the Abdomen.— The
superficial lymphatic vessels of the walls of the abdomen follow the course of the
superficial blood-vessels. The superficial lymphatics are derived from the integu-
ment. Those of the lower part of the abdomen below the umbilicus follow the course
of the superficial epigastric vessels and converge to the superior group of the super-
ficial inguinal glands (Figs. 499 and 501). Those from the costal margins of the
abdomen terminate in the axillary glands (Fig. 495). The superficial lymphatics
from the sides of the lumbar part of the abdominal wall wind around the crest of
the ilium, accompanying the superficial circumflex iliac vessels, to join the super-
ficial inguinal glands (Fig. 499).
The Superficial Lymphatic Vessels of the Gluteal Region. — The superficial lym-
phatic vessels of the gluteal region turn horizontally around the outer side of the
nates, and join the superficial inguinal glands.
The Superficial Lymphatic Vessels of the Scrotum and Perinseum. — The superficial
lymphatic vessels of the scrotum and perinseum terminate in the superficial inguinal
glands.
The Superficial Lymphatic Vessels of the Penis. — The superficial lymphatic vessels
of the penis occupy the sides and dorsum of the organ, the latter receiving the
lymphatics from the prepuce; they all converge to the superficial inguinal glands.
Lymph vessels from the glans penis empty into the deep inguinal and the external
iliac glands.
In the female the lymphatic vessels of the vulva and prepuce of the clitoris pass
to the superficial inguinal glands; those of the glans of the clitoris pass to the
deep inguinal and the external iliac glands.
The Deep Lymphatic Vessels of the Abdominal Wall. — The deep lymphatic
vessels of the abdominal wall take the course of the principal blood-vessels, and
arise from muscular or aponeurotic layers. One set of lymph-vessels runs along
with the deep epigastric artery and terminates in the external iliac glands. Another
accompanies the deep circumflex iliac artery, and also terminates in the external
iliac glands. Several lymph-vessels accompany the lumbar arteries and empty
into the juxta-aortic glands. A vessel accompanies the internal mammary artery
and empties into the internal mammary glands. Lymph-vessels of the parietes of
the pelvis, which accompany the gluteal, ischiatic, and obturator vessels, follow
the course of the internal iliac artery, and ultimately join the external iliac, internal
iliac, and common iliac glands, and the glands about the lower portions of the aorta
and vena cava.
The Lymphatic Vessels of the Umbilicus. — The lymphatics of the umbilicus are
divided into three groups:1 The cutaneous lymphatics, which are very superficial,
1 The Lymphatics. By Poirier, CuneY>, and Deiamare. Translated and edited by Cecil H. Leaf.
800 THE LYMPHATIC SYSTEM
and empty into the superficial inguinal glands. The lymphatics of the fibrous
nucleus, which pass through the rectus sheath, reach the deep epigastric artery
and join the deep lymphatics which come from the muscular and aponeurotic
layers of the belly wall. The lymphatics of the aponeurotic margin are in two sets:
An anterior set, some of which penetrate the rectus sheath and join the lymphatics
from the fibrous nucleus; others of which pass outward, penetrate the external and
internal oblique muscles, and join the posterior lymph-vessels from the aponeu-
rotic margin. A posterior set, which forms a collection of vessels on the posterior
aspect of the rectus sheath, from which several trunks emerge. One trunk passes
outward, penetrates the Transversalis muscle, joins the anterior trunk from the
aponeurotic margin, and empties into the external iliac glands.1 Other ducts run
along with the deep epigastric artery and pass into the external iliac glands.
Glands lie along the lower portion of these lymph-ducts, and are known as
the superior epigastric glands, and a gland may exist in the subperitoneal tissue
beneath the umbilicus.
The Lymphatic Vessels of the Peritoneum. — It seems probable that the peritoneal
cavity is a lymph-sac and that lymphatics take origin from the peritoneum in
several ways. Robinson2 points out three modes of origin : 1. By stomata between
endothelial cells. These stomata are in direct communication with lymph-vessels.
2. By interstitial spaces in the subperitoneal tissue. 3. By a plexiform origin
similar to interstitial spaces.
Surgical Anatomy. — The fact emphasized by Robinson that the peritoneum is a great
lymph-sac explains the quick absorption of septic material and the rapid spread of infectious pro-
cesses. If the exudate clots and blocks the lymph-channels, absorption is slew and life may be
saved. If it does not clot, absorption is rapid and death is certain. Whether it clots or not
depends on the nature of the bacteria present.3 Fowler, impressed by the fact that absorption
takes place most rapidly from the diaphragmatic region and least rapidly from the pelvic region,
advises placing the victim of peritonitis in bed, with his head and body elevated.4
The Lymphatic Vessels of the Bladder. — No lymphatics exist in the mucous mem-
brane of the bladder, although they do exist in the mucous membrane of the pros-
tate. There are some lymphatics in the bladder muscle, and numerous lymphatics
in the subperitoneal tissue. The network of lymph-vessels in the muscles is con-
nected with the network beneath the peritoneum and prevesical fascia, and collect-
ing trunks come from both the anterior and posterior surfaces of the bladder.
The anterior collecting trunks are divided into two sets. One set comes from the
inferior portion of the anterior surface and passes outward to terminate in an
external iliac gland "between the external iliac vein and the obturator nerve."5
The other set comes from the superior and anterior vesical surface, runs upward
and outward, and terminates in the external iliac glands. Each set of vessels
possesses interrupting lymph-nodes, some of which are directly in front of the
bladder.
The posterior collecting trunks are divided into four sets. The first set comes
from the superior and posterior portion and passes outward, exhibiting interrupting
nodes in its course. These trunks terminate in the external iliac glands. The
second set runs directly back into the external iliac glands. The third set comes
from the middle of the posterior portion of the bladder and terminates in the
hypogastric glands. The fourth set comes from the vesical neck, passes back
and then ascends and terminates in the glands in front of the sacral promontory.
This fourth set joins with the lymphatics from the prostate and seminal vesicles.
The Lymphatic Vessels of the Prostate Gland. — These vessels form a peri-pros-
tatic plexus, which receives its afferents from the gland structure. This plexus is
drained by four vessels, three of which commence on the posterior surface of the
1 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf.
2 The Peritoneum. 8 Ibid.
4 George Ryerson Fowler, on Diffuse Septic Peritonitis, in the Medical Record, April 14, 1900.
6 The Lymphatics. By Poirier, CuneY>, and Delamare. Translated and edited by Cecil H. Leaf.
THE LYMPHATIC VESSEL8 OF THE ABDOMEN AND PELVIS 801
gland . Although these vessels begin on the posterior surface of the prostate, their
termination in each case is different. One passes on the under surface of the
bladder, crosses the superior vesical artery, runs outward, and ends in the middle
chain of the external iliac group. Another passes upward, outward, and back-
ward, and terminates in the hypogastric group. A third passes along the
floor of the pelvis, runs by the side of the rectum, and ascends on the anterior
surface of the sacrum to terminate in the lateral sacral glands and in the hypo-
gastric group. Occasionally a fourth trunk is found on the anterior surface of
the prostate, which descends and joins the vessels from the membranous urethra
and ends in the hypogastric glands.
The Lymphatic Vessels of the Male Urethra. — These vessels are divided into two
groups: First, those of the penile portion of the urethra; second, those of the bulb
and membranous portion. The lymphatics of the prostatic urethra belong to those
of the prostate gland. The lymph-vessels of the penile urethra in front of the
sulcus all run toward the freenum, at which point they bend backward to the sul-
cus; here they run to the dorsal surface of the penis and terminate in the same man-
ner as the vessels from the glans. The trunks from the remainder of the penile
urethra emerge from the inferior surface, run around the corpus cavernosa, and
mostly unite with the vessels from the glans penis. One vessel, though, passes over
the symphysis and enters in the internal retro-crural gland, whilst another passes
beneath the symphysis and terminates with the vessels from the bulb and mem-
branous portion of the urethra. The lymphatics of the bulb and membranous
portions end in three trunks, one of which accompanies first the artery of the bulb
and then the internal pudic artery, and ends in the hypogastric gland attached to
the pelvic portion of this artery. A second trunk runs behind the pubes, to end
in the internal retro-crural gland. A third trunk runs on the bladder, where it
joins with vessels from this organ, to end in the internal chain of external iliac
glands.
The Lymphatic Vessels of the Female Urethra. — The lymphatics of the female
urethra terminate in the same manner as do the lymphatics of the bulb and mem-
branous portions of the male urethra
The Lymphatic Vessels of the Uterus. — These consist of three sets, each of which
arises by a network of capillaries. There is a mucous network, a muscular network,
and a peritoneal network. The vessels from these three regions of origin are col-
lected in the subperitoneal tissue, from which area the collecting trunks take origin.
From the cervix, according to Poirier and Cune"o, come from five to eight collecting
trunks, which pass toward the sides of the body of the uterus, forming on each
side, by twisting and dilatation, the juxta-cervical lymphatic knot of Cune"o. The
cervical connecting trunks are divisible into three groups on each side. One group
is composed of two vessels, which pass to the middle chain of the external iliac
glands (superior and middle glands). Another group is composed of two vessels,
which enter the hypogastric glands. A third group is composed of several vessels,
some of which enter the lateral sacral glands, and the balance of which terminate
in the glands of the sacral promontory. From the body of the uterus come three
groups on each side. One group is composed of four or five vessels which emerge
below the uterine cornu, pass beneath the ovary, where they receive the ovarian
lymphatics, and terminate in the juxta-aortic glands of the same side. One
so-called accessory lymphatic pedicle terminates in the external iliac glands, the
other in the inguinal glands.
The Lymphatic Vessels of the Fallopian Tube. — The lymphatics of the Fallopian
tube join with those of the uterus and ovary and terminate in the lateral aortic
glands.
The Lymphatic Vessels of 'the Ovary. — The ovary is extremely rich in lymphatics;
they form a plexus which is superficial to the veins. The vessels leading from this
plexus, four or five in number, pass upward in company with the ovarian vessels
51
802 THE LYMPHATIC SYSTEM
and end in the lateral aortic glands. Above the firth lumbar vertebra these ves-
sels anastomose with the lymphatics from the fundus of the uterus and Fallopian
tube. Quite often there is a lymph-vessel which emerges from the ovary, passes
downward and outward and ends in the middle chain of the internal iliac glands.
The Lymphatic Vessels of the Vagina. — The lymphatics of the vagina are divided
into those of the mucous coat and those of the muscular coat; these anastomose
freely with each other and terminate in a peri-vaginal network, which is drained
by three groups of trunks. One group drains the upper third of the vagina and
passes to the middle chain of the external iliac glands. A second group is efferent
to the middle third of the vagina and ends in the hypogastric glands. A third
group carries the lymph from the lower third of the vagina to the gland of the
promontory.
The Lymphatic Vessels of the Testicle. — The lymphatic vessels of the testicle
consist of two sets, superficial and deep; the former commence on the visceral sur-
face of the tunica vaginalis, the latter in the epididymis and body of the testis.
They form several large trunks which ascend with the spermatic cord, and, accom-
panying the spermatic vessels into the abdomen, terminate in the juxta-aortic
and sometimes also in the pre-aortic glands ; hence the enlargement of these glands
in malignant disease of the testis.
The Lymphatic Vessels of the Vas Deferens. — These lymphatics empty into the
external iliac glands.
The Lymphatic Vessels of the Seminal Vesicles. — A network exists on the surface
of each vesicle, formed by a collection of lymph-vessels from the mucous lining and
from the muscular structure of the vesicle. The trunks from this network empty
into the external and internal iliac glands.
The Lymphatic Vessels of the Kidney, Ureter, and Suprarenal Capsule. — Their
courses and terminations differ on the two sides. They take origin from a super-
ficial network just beneath the capsule of the kidney and a deep network in the in-
terior of the organ. The superficial network is connected to the collecting vessels
of the deep network at the hilum. From the superficial network numerous ves-
sels penetrate the capsule of the kidney and join the lymphatics of the fatty cap-
sule. According to Poirier, Cune"o, and Delamare,1 anterior and posterior trunks
come off from the deep lymphatics of the right kidney. The anterior trunk
usually terminates in the right juxta-aortic glands which lie upon the vena cava.
The posterior trunks terminate in the juxta-aortic glands which lie behind the
vena cava. On the left side all the collecting trunks terminate in the juxta-aortic
glands of the left side of the aorta.
The lymphatics of the fatty capsule of the kidney communicate with the lym-
phatics of the kidney, and both terminate in the same glands. The lymphatics of
the suprarenal capsule terminate in the juxta-aortic glands of the same side. From
the ureter lymph-vessels come off and terminate in the juxta-aortic and adjacent
glands.
The Lymphatic Vessels of the Liver. — The lymphatic vessels of the liver are
divisible into two sets, superficial and deep. The former arise in the lobules at the
periphery of the liver and pass to the subperitoneal connective tissue over the
entire organ. The latter arise from the deeper lobules, and emerge from the liver
along the portal vein or the hepatic veins.
According to Poirier, Cune"o, and Delamare,2 three groups of superficial collect-
ing trunks arise from the subperitoneal network. The posterior trunks divide
into three groups. The single right posterior trunk terminates in a gland about the
creliac axis. The middle posterior trunks (five to seven in number) pass through
the opening in the Diaphragm. The left posterior trunks pass into glands
1 The Lymphatics. Translated and edited by Cecil H. Leaf. 2 Ibid.
THE LYMPHATIC VESSELS OF THE ABDOMEN AND PELVIS 803
about the subdiaphragmatic portion of the oesophagus. The anterior collecting
trunks terminate in the lymph-glands of the hilum of the liver. The superior
trunks ascend. One of these trunks or a posterior trunk passes with the vena cava
through the Diaphragm and terminates in glands about the vena cava. Another
trunk, an anterior one, passes over the anterior border of the liver, runs for a time
with the round ligament, and terminates in the hepatic glands. Numerous middle
trunks ascend in the suspensory ligament, unite beneath the Diaphragm into a
short trunk of large size, which passes through the Diaphragm and divides into
several smaller ducts, which terminate in the glands back of the xiphoid cartilage.
Trunks from the superficial lymphatic network also emerge from the inferior
surface of the liver. The posterior trunks from the right lobe reach the vena cava
and terminate in the glands about the intra-thoracic end of that vessel. The
middle and anterior trunks from the right lobe reach the glands along the cystic
duct. The trunks from the left lobe terminate in the glands along the hepatic
artery. The trunks from the lobus Spigelii reach the glands of the hilum and the
glands about the lower intra-thoracic portion of the vena cava. The trunks from
the quadrate lobe terminate in the glands of the hilum. The deep collecting trunks
LEFT LATERAL
LIGAMENT
OBLITERATED
UMBILICAL VEIN
FIG. 504. — Lymphatics of the inferior surface of the liver. (Sappey.)
are divisible into two groups. One group descends along the portal vein, the other
ascends along the hepatic veins.
Sappey pointed out that the deep descending trunks accompany the bile pass-
ages and the branches of the portal vein, several anastomosing vessels accom-
panying each branch of the portal vein. The same authority affirmed that from
fifteen to eighteen trunks emerge from the hilum and terminate in the adjacent
glands. The deep ascending trunks surround as a sheath the branches of the
hepatic vein (Sappey). As they approach the Diaphragm they diminish in num-
ber to five or six, pass through the opening for the vena cava, and terminate in
the glands about the lower portion of the intra-thoracic cava.
The Lymphatic Vessels of the Bile-ducts. — The lymphatics of the bile-ducts arise
from the mucous membrane and from within the muscular tissue, and terminate
in glands along the cystic and common ducts.
804 THE L YMPHA TIG SYSTEM
The Lymphatic Vessels of the Stomach (Figs. 505 and 506).— The lymphatic
vessels of the stomach consist of two sets, superficial and deep. The superficial
arise from the outer (serous) and the middle (muscular) coats. The deep arise
from the mucous membrane and form a network in the submucous tissue. Trunks
from the submucous network pass through the muscular tunic and terminate in
the trunks coming from the sero-muscular layers. These latter, the musculo-serous
CORONARY
CURRENT
RIGHT
CASTRO-EPIPLOIC
CURRENT
FIG. 507. — Lymphatic areas of the stomach. (Cuneo.)
collecting trunks, are divided into three groups. The first group is composed of six
or eight vessels which pass toward the lesser curvature (Sappey). There are from
three to ten glands upon the lesser curvature along the course of the gastric artery
which receive these superior trunks. Vessels come to these glands from the cardia,
from the body of the stomach, and from the pyloric end. In the lesser curvature
the lymphatic vessels lie in the wall of the stomach. According to Cun^o, two-
thirds of" the stomach is drained by the lymph-vessels of group I. The second
group comprises the trunks from the greater curvature which end in the subpyloric
glands. The glands along the greater curvature are some distance from the
stomach wall in the pyloric region, and lymph-streams flow from left to right, that
is, toward the pylorus and not from it. These lymphatics drain one-third of the
stomach. The first and second groups send lymph eventually to the coeliac
glands and juxta-aortic glands. The third group comprises trunks which come
from the fundus of the stomach and enter the lymphatic glands about the spleen.
Surgical Anatomy. — Mikulicz pointed out the early infection of the glands of the lesser curva-
ture in pyloric cancer, and insisted that in operation for pyloric cancer the entire lesser curvature
must be removed. Cune*o showed us that in pyloric cancer the fundus and two-thirds of the
greater curvature1 usually remain free from disease, because the lymph-current is toward the
pylorus and not from it. Of course, if the lymphatics become blocked, the lymph-current may
be reversed (regurgitation), and then infection of these parts can occur. William J. Mayo has
noted the ''lymphatic isolation" of the dome of the stomach. In operating for cancer of the
pylorus, make the section of the stomach as directed by Hartmann, that is, a section which
removes all of the lesser curvature and cuts the greater curvature well to the left of the subpyloric
glands.
The Lymphatic Vessels of the Pancreas. — The lymphatics of the pancreas arise
from a network about the pancreatic lobules. The collecting trunks anastomose
freely on the surface of the pancreas. Some of the trunks terminate in the
splenic glands, which send vessels to the coeliac glands. Others terminate directly
in the coeliac glands. The lymphatics of the head of the pancreas communicate
with the duodenal lymphatics and the lymphatics of the lower end of the com-
mon duct. The pancreatic and splenic lymphatics probably communicate.
The Lymphatic Vessels of the Spleen. — The lymphatics of the spleen consist of
two sets, superficial and deep; the former are placed beneath its peritoneal covering,
the latter in the substance of the organ; they accompany the blood-vessels, passing
THE LYMPHATIC SYSTEM OF THE INTESTINES
805
through a series of small glands, and pass into the splenic glands which are placed
in the omentum between the spleen and pancreas. The gastro-splenic omentum
contains no glands.
THE LYMPHATIC SYSTEM OF THE INTESTINES.
The Lymphatic Glands of the Small Intestine (Fig. 507).— The lymphatic
glands of the small intestine are placed between the layers of the mesentery, and are
LEFT VAGUS.
NERVE
RIGHT CASTRO
EPIPLOIC ARTERY
SUBPYLORIC
GLAND
CORONARY
VEIN
GLANDS OF THE
LESSER CURVATURE
RIGHT GASTRO-
CPIPLOIC VEIN
FIG. 506. — General view of the subperitoneal lymphatic plexus of the stomach prepared by the method of
Gerota. (Cune'o.)
called mesentery glands (lymphoglandulae mesentericae) . They vary in number from
a hundred to a hundred and fifty, and in size from that of a pea to that of a small
almond.1 These glands are most numerous and largest above, the glands of the
jejunum being more numerous than those of the ileum. This latter group becomes
enlarged and infiltrated with deposit in cases of fever accompanied with ulceration
of the intestines. The glands diminish in number as we descend until the ileo-
csecal region is reached, when a number of glands appear about the ileo-csecal
artery. The mesenteric glands receive the lacteals and send out trunks to the
receptaculum chyli. The chyle from the intestine passes through the glands on
its way to the thoracic duct.
The glands may be divided into: I. A group of glands the members of which
are chiefly found along the terminal vessels from the vascular loops of the intestinal
branches of the superior mesenteric artery. Some glands of this group are placed
upon "the anterior surface of the upper end of the jejunum."2 II. A group of
1 Leaf (Surgical Anatomy of the Lymphatic Glands) says it is very common to find not more than forty or
fifty. 2 Ibid.
806 THE LYMPHATIC SYSTEM
glands along the vascular loops of the superior mesenteric artery. Most of them
are between the primary loops. Some of them are between the secondary and
tertiary loops. III. A group of glands along the trunk of the superior mesenteric
artery.
FIG. 507. — Lymphatics of the small intestine.. (Poirier and Charpy.)
The Lymphatic Vessels of the Small Intestine (Fig. 507).— The lymphatic
vessels of the small intestine are called lacteals, from the milk-white fluid they
usually contain. They take origin in the intestinal villi and in lymphatic sinuses
around the bases of the solitary glands. Lymphatic plexuses exist in the submucous
tissue, the muscular coat, and the subserous tissue. The lymphatic vessels pass
between the layers of the mesentery, enter the mesenteric glands, and finally unite
to form two or three large trunks which terminate separately in the receptaculum
chyli; frequently, however, they first unite to form a single large trunk, termed the
intestinal lymphatic trunk (Figs. 483 and 509).
The Lymphatic Glands of the Large Intestine. — The lymphatic glands of
the large intestine are divided into the colic glands and rectal glands. ,
The Colic Glands (lymphoglandulae coliacae). — The colic glands are subdivided
into: 1. The ileo-colic or ileo-csecal glands (Fig. 508), which lie along the course
of the ileo-colic artery, one or two of the glands being placed upon the anterior
surface of the caecum. The mesoappendix also contains a gland which com-
municates with glands in the mesocolon, and receives lymph from the appendix
and, in the female, from the ovary. 2. Glands in the mesocolon along the right
colic artery, which receive lymph from the ascending colon and the hepatic flexure.
3. Glands in the mesocolon along the middle colic artery, which receive lymph
from the hepatic flexure and transverse colon. 4. Glands in the mesocolon
along the left colic artery, which receive lymph from the descending colon and
sigmoid flexure. The vessels from the colic glands pass to the pre-aortic
glands.
The Rectal Glands. — The rectal glands lie in the mesorectum; they receive lymph
from the anus and rectum and it passes from them to the lumbar and sacral glands.
The Lymphatic Vessels of the Large Intestine. — The lymphatic vessels of the
large intestine consist of three sets: those of the caecum, ascending and transverse
colon, which, after passing through their proper glands, enter the mesenteric
glands; those of the descending colon and sigmoid flexure, which pass to the lumbar
THE LYMPHATIC GLANDS OF THE THORACIC WALL 807
glands, and those of the rectum and anus, which pass to the sacral and superficial
inguinal glands.
Lymphatics of the Anus and Rectum. — These vessels take origin from two
networks, one from the skin and mucous membrane and the other from the mus-
cular coat. The lymph-vessels from the skin at the anal margin pass to the super-
ficial inguinal glands. Some vessels from the skin of the anus ascend and reach
the submucous plexus of the rectum, from which region lymph-vessels pass to
the rectal glands, to the glands along the middle hemorrhoidal artery, and along
the inferior hemorrhoidal artery, and to a pelvic gland near the origin of the
internal pudic artery.1 The vessels from the anal mucous membrane and from
the muscular wall of the rectum penetrate the muscular wall of the rectum
with the arteries and reach the rectal glands.
ANTERIOR
LYMPHATICS
OF OECUM
ANTERIOR
C/ECAL
GLAND OF
APPENDIX
APPENDICULAR
EFFERENT
LYMPHATICS
FIG. 508.— Anterior view of the lymphatics of the ca-cum and appendix. (Poirier and Charpy.)
THE LYMPHATICS OF THE THORAX.
The thoracic lymphatics are divided into the deep lymphatics of the chest wall,
the diaphragmatic lymphatics, and the visceral lymphatics.
The Lymphatic Glands of the Thoracic Wall or the Parietal Lymphatics.
The lymphatic glands of the thoracic wall include the internal mammary and
intercostal glands.
The Internal Mammary Glands. — The internal mammary, retro-sternal, or
sternal glands (lymphoglandulae sternales) form a chain of five or six glands on each
side of the sternum along the course of the corresponding internal mammary artery,
and back of the Internal intercostal muscles. The glands are separated from the
pleura by cellular tissue. The internal mammary glands receive vessels from the
diaphragmatic glands, the abdominal muscles above the umbilicus, the anterior
' The Lymphatics. By Poirier, Cun£o, and Delamare. Translated and edited by Cecil H. Leaf.
808 THE LYMPHATIC SYSTEM
ends of the intercostal spaces, the skin over the sternum, and the mammary gland.
The vessels given off by each chain from a single trunk. On the right side this
trunk terminates at the junction of the internal jugular and subclavian veins,
unites with the subclavian lymph-trunk to form the right lymphatic duct, or
empties directly into the subclavian trunk (Fig. 485). On the left side it empties
either at the junction of the subclavian and internal jugular veins or into the
thoracic duct.
The Intercostal Glands (lymphoglandulae intercostales) (Fig. 509).— The inter-
costal glands are small glands lying in the intercostal spaces along the intercostal
arteries. In the posterior end of each space they are constantly found. These are
called the posterior glands, and there are one, two, or three in each space. These
glands are opposite the neck of the rib or over the articulation of the rib with the
vertebra. The pleura is in front of them, and they lie upon the external inter-
costal muscles. In the middle of the intercostal spaces are inconstant glands
which are called lateral glands. They are merely interrupting nodes in the
trunks from the intercostal muscles. The intercostal glands receive vessels from
the intercostal muscles and pleura. They send vessels back toward the spine,
which unite with lymphatics from the back part of the thorax and spinal canal,
and which pass down the spine and terminate in the thoracic duct.
The Diaphragmatic Lymphatics.— The diaphragmatic lymph-glands are dis-
tinct and numerous. These glands are on the convex surface of the Diaphragm
and are divided into an anterior, a middle, and a posterior group. They receive
vessels from the Diaphragm and liver and send vessels to the internal mammary
and posterior mediastinal glands. The lymph-vessels of the Diaphragm take
origin from a capillary network contained in the spaces between the muscular
and tendinous fasciculi of the Diaphragm. Numerous lymph-vessels descend
until they reach the subperitoneal tissues and then ascend. Others immediately
ascend to beneath the pleura. The collecting trunks are all on the convex surface
of the Diaphragm. The lymphatic vessels of the Diaphragm anastomose with
the lymphatic vessels of the pleura and the peritoneum. This subperitoneal
network is so extensive that absorption in this region is extremely rapid.
Hence, after an abdominal operation, if salt solution has been left in the ab-
domen, it will be very rapidly absorbed if the foot of the bed is elevated.
Influenced by the knowledge that the pelvic peritoneum absorbs comparatively
slowly and the peritoneum in the upper abdomen very rapidly, and that septic
processes in the upper abdomen are more rapidly fatal than septic processes in
the pelvis, Fowler was led to recommend the elevation of the head of the bed
after operations for abdominal infections. This posture causes poisonous fluids
to gravitate away from the Diaphragm.
The Visceral Lymphatics. — The visceral lymphatics include the anterior medi-
astinal glands, the posterior mediastinal glands, and the peritracheo-bronchial glands.
The Anterior Mediastinal Glands (lymphoglandulae mediastinales anteriores) . — The
anterior mediastinal glands are in the upper portion of the anterior mediastinum,
a group of six or seven glands lying above and upon the front of the transverse
portion of the arch of the aorta and sending glandular chains toward the neck.
On the right side these glands are found between the innominate artery and vein
and in front of the vein. On the left side they are in front of and behind the left
common carotid and left subclavian arteries. They receive lymph from the heart,
pericardium, thymus gland, and anterior mediastinum.
The Posterior Mediastinal Glands (lymphoglandulae mediastinales posteriores)
(Fig. 509). — The posterior mediastinal glands are behind the pericardium and
in front of the oesophagus. Occasionally one or two are placed back of the
oesophagus. They receive vessels from the intercostal glands, aortic glands,
deep cervical glands, and pleura, and send vessels to the thoracic duct.
THE LYMPHATIC GLANDS OF THE THORACIC WALL
809
The Peritracheo-bronchial Glands. — The peritracheo-bronchial glands are divided
by Bare"ty into four groups. One group is in the angle formed by the junction
of the trachea and right bronchus. Another group is in a corresponding situation
on the left side. Another group is below the tracheal bifurcation. The glands of
the fourth group are about the points of division of the larger bronchi. The
peritracheo-bronchial glands receive lymph-vessels from the lung, heart, peri-
cardium, oesophagus, trachea, and thymus.
MEDIASTINAL
GLANDS AND
VESSELS
INTERCOSTAL
GLANDS AND
VESSELS
COMMON INTES
TINAL TRUNK
PRE-AORTIC
GLANDS AND
VESSELS
COMMON INTES-
TINAL TRUNK
INTERNAL ILIAC
EXTERNAL ILIAC
FIG. 509; — Deep lymphatic glands and vessels of the thorax and abdomen (diagrammatic). Afferent vessels are
represented by continuous lines, and efferent and interglandular vessels by dotted lines. (Cunningham.)
In infancy these glands present the same appearance as the lymphatic glands in other situa-
tions. In early adult life they assume a brownish tinge, and in old age become deep black,
because they arrest particles of carbon brought from the bronchi. This change is known as
anthracosis, and the darkened glands are usually sclerotic. In fact, in old age these glands often
lose all lymphatic characters and become fibrous masses. These glands enlarge from infection,
8 1 0 THE L YMPHA TIC SYSTEM
and when very large may compress the bronchi, the pulmonary artery, etc. They are often the
seat of tuberculous deposits.
The Lymphatic Vessels of the Thoracic Wall.— The lymphatic vessels of the
thoracic Wall include the deep lymphatic vessels, intercostal and internal mammary,
which have been described, the cutaneous lymphatics, and the lymphatics of the
mammary gland.
The Cutaneous Lymphatics (Fig. 495).— The area drained by these lymphatics
is very extensive. It is divided by Poirier, Cune'o, and Delamare into three regions.
The anterior region extends from over the middle of the sternum to the anterior axil-
lary line. The trunks pass to the axilla and terminate in the thoracic chain of the
axillary glands. From this anterior region some accessory trunks pass above the
clavicle and reach the supra-clavicular glands, and trunks may arise to one side
of the mid-sternal line and pass to the opposite axilla. From the lateral region the
trunks ascend to the thoracic chain of axillary glands. This region is between
the anterior and posterior axillary lines. The posterior region is back of the
posterior axillary line, and includes the thorax to the mid-line, and the posterior
portion of the root of the neck. The trunks from the posterior area empty into
the scapular group of axillary glands.
Lymphatics of the Mammary Gland (Figs. 494 and 510).— There are two sets
of lymphatics in this gland, the cutaneous or superficial and the glandular or deep.
The Peripheral Cutaneous Lymphatics of the Mammary Gland. — The peripheral
cutaneous lymphatics do not arise from the nipple. Their collecting trunks are
arranged as are other collecting trunks of the anterior portion of the thorax, and
end in the thoracic group of axillary glands of the same side. Trunks arising from
the sternal margin of the skin of the breast may run to the glands of the opposite
axilla.
The Central Deep Lymphatics of the Mammary Gland. — The central lymphatics
form a very extensive network in the nipple and areola, and from this network
numerous vessels pass into a plexus beneath the areola, Sappey's subareolar plexus;
most of the trunks coming from the gland also enter the subareolar plexus.
The Glandular Lymphatics of the Mammary Gland. — The glandular lymphatics
arise from spaces about the lobules and from networks about the milk-ducts. We
can distinguish a chief lymphatic channel and three accessory channels.
The chief lymphatic channel takes origin from collecting trunks which begin
in the spaces about the lobules and in the lymph-capillaries about the milk-ducts.
These collectors pass toward the nipple and terminate in the subareolar plexus,
which plexus also receives the vessels from the areola and nipple. Two large
trunks take origin from the subareolar plexus: one from its inner side, the other
from its outer side. "The internal trunk runs at first downward and then out-
ward, turning round the inferior border of the subareolar plexus. It is thus
directed toward the axilla and runs in the subcutaneous cellular tissue, along the
lower border of the Pectoralis major, which it crosses at the level of the third
rib to reach the base of the axilla. This collecting trunk constantly receives as
afferents one or two fair-sized trunks coining directly from the inferior portion of
the mammary gland. The external trunk, which is usually smaller than the pre-
ceding, runs directly outward toward the axilla. Before it reaches the latter it
is augmented by a vessel coming from the superior part of the gland. At the base
of the axilla these two collecting trunks perforate the axillary aponeurosis and
terminate in one or two glands, placed on the inner wall of the axilla on the third
digitation of the Serratus magnus muscle. These glands (the principal regional
glands of the breast) may or may not be covered by the lower part of the Pec-
toralis major muscle according to the muscular development of the subject (Sur-
gius)."1 These glands constitute the supero-internal mass of the anterior axillary
1 The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf.
THE LYMPHATIC GLANDS OF THE THORACIC WALL 811
chain. An interrupting gland is sometimes found in the course of these two
trunks, the paramammary gland.
The Accessory Channels from the Mammary Gland. — The accessory channels from
the mammary gland, according to Poirier, Cune*o, and Delamare, are three. They
call one the accessory axillary channel. It is not constant, and there may be inter-
rupting glands on its collectors. Its collectors come off from the inferior portion
of the mammary gland and pass directly to the axillary glands. Another channel
is the subclavian channel. Neither is it constant. It comes off from the posterior
surface of the mammary gland, pierces the great Pectoral muscle, and ascends
between the greater and lesser Pectorals to reach the subclavian glands. There
FIG. 510. — The vessels and lymphatics of the anterior face of the mammary glands. (Sappey.)
are usually interrupting glands along this channel, the retro-pectoral glands. The
subclavian channel runs along the superior thoracic artery. They call the third
accessory channel the internal mammary channel. The collecting trunks arise
from the inner portion of the mammary gland and pass along the vessels sent off
from the internal mammary artery to the gland. They pierce the Pectoral and
Intercostal muscles and reach the internal mammary glands. This channel is
constant and along it there may be interrupting glands.
Lymphatics of the Great Pectoral Muscle. — The lymphatics of the great Pectoral
muscle end in the subclavian glands, the thoracic group of axillary glands, and
the internal mammary glands.
Surgical Anatomy. — A knowledge of the lymphatics of the breast and of the glands into which
the lymphatics drain is of the first importance to a surgeon. Certain surgical deductions from
the anatomy of this region are perfectly obvious — viz. : 1 . If the skin of the mammary gland is
involved in carcinoma, the thoracic group of axillary glands of the same side is involved. If the
skin over the sternal margin of the gland is involved, the glands of the opposite axilla may be can-
cerous, as from this point lymph-vessels rise and pass across the mid-line. If the skin of the
sternal margin is involved the prognosis is worse than if it is free, the opposite axilla may be
cancerous, and the opposite breast may become diseased. 2. When lymphatic ducts become
blocked by cancer cells the lymph backs up, flows backward instead of in its proper direc-
812 THE L YMPHA TIC SYSTEM
tion, and may cause infection in the most unsuspected situations. For instance, a block in the
cutaneous lymphatics of a portion of the breast may lead to infection of the opposite breast and
axilla, though, of course, it is not so likely to as is cancer of the skin of the sternal margin. By
regurgitation of lymph the head of the humerus or the retro-sternal structures may become dis-
eased in mammary cancer. 3. If the nipple or areola is cancerous, the entire gland is sure to be
diseased, as the lymphatic network of this region empties into the subareolar plexus, and most
of the trunks coming from the gland also enter this plexus. 4. If the mammary gland is cancer-
ous, all of the axillary glands are regarded as diseased, as the main lymphatic channel from the
breast reaches the glands on the inner wall of the axilla upon the third digitation of the Ser-
ratus magnus. Furthermore, in many cases an accessory lymph-channel comes off from the
lower portion of the mammary gland and passes directly to the axilla. 5. The subclavian glands
are to be regarded as diseased, because in a certain proportion of cases (the exact proportion
being uncertain) an accessory lymph-channel comes off from the posterior surface of the mam-
mary gland, passes through the great Pectoral muscle and ascends between the greater and
lesser Pectorals to reach the subclavian glands. 6. The element which greatly interferes with
the cure of mammary carcinoma is the existence of lymph-channels which arise from the inner
portion of the mammary gland, pierce the greater Pectoral and Internal intercostal muscles, and
reach the internal mammary glands. Mediastinal involvement is apt to be earlier in carcinoma
of the inner portion of the breast than in carcinoma of other portions, and the prognosis is par-
ticularly bad in cancer of the inner portion of the breast. What is known as the sternal symptom
of Snow is bulging of the sternum due to involvement of the thymus gland. 7. The sternal
portion of the great Pectoral and the tissue between it and the lesser Pectoral muscle are to be
regarded as diseased, because in some cases an accessory lymph-channel from the breast pene-
trates the greater Pectoral and ascends to the subclavian glands. This trunk has several inter-
rupting or satellite glands, the retro-pectoral glands, in the tissue back of the great Pectoral
muscle. 8. When the great Pectoral muscle is diseased, cancer cells soon spread widely through
the sternal portion of the muscle, and this entire portion of the muscle becomes cancerous. The
clavicular portion does not suffer early, but escapes until the cancer becomes extensive, as it
is anatomically distinct from the sternal portion. If the fibres of the great Pectoral are exten-
sively diseased, the thoracic group of axillary glands, the subclavian glands, and possibly the
internal mammary glands are involved. 9. The only operation in cancer of the breast which
offers any real hope of cure is one which is done early and is radical. 10. It must be done
early, because delay permits involvement of the mediastinum, and if the disease has entered
the mediastinum operation is hopeless. If the sternum is bulged operation is useless, and
nothing short of amputation at the shoulder-joint could be of help if the head of the humerus
is enlarged by the disease. Even this radical procedure is of no avail, because the mediastinum
is certainly involved if the head of the humerus is diseased. 11. If the lymph-glands above
the clavicle are extensively diseased operation is useless, as in such cases the mediastinum is
sure to be involved. 12. A radical operation means the removal of the skin of the breast with
the nipple and areola, the subcutaneous tissue of this region, the entire breast the sternal
portion of the great Pectoral with its fascia, the retro-pectoral glands and tissue, all the con-
tents of the axilla except vessels and nerves, the glands and cellular tissue beneath the anterior
margin of the Latissimus dorsi, and the subclavian glands. It is probably always wisest to
open above the clavicle as well as below to facilitate the removal of glands. It is seldom necessary
to remove the clavicular portion of the greater Pectoral. The lesser Pectoral does not require
removal, but it should be taken away, because of the added safety and speed thus obtained
in cleaning the great vessels and because its retention does not improve the functional result.
The surgeon must remember that the breast is a much larger organ than we used to think, and
all of its irregular projections and outlying lobules must be removed (p. 791). Formerly,
surgeons did not completely remove the breast, but only got rid of a large portion of it.
The Pulmonary Lymphatics. — The pulmonary lymphatics arise from net-
works between the lobules, around the bronchi and under the mucous membrane.
The collecting trunks are in two sets, superficial and deep: the former are placed
beneath the pleura, forming a minute plexus which covers the outer surface of
the lung; the latter accompany the blood-vessels and run along the bronchi; they
both terminate at the root of the lungs in the tracheo-bronchial glands.
The Pleural Lymphatics. — The lymphatics of the pulmonary pleura pass into the
superficial pulmonary trunks; those from the costal pleura enter the intercostal
trunks; those from the diaphragmatic pleura enter the diaphragmatic trunks, and
those from the mediastinal pleura enter the posterior mediastinal glands.1
The Cardiac Lymphatic Vessels. — The cardiac lymphatic vessels consist of
two sets, superficial and deep: the former arise in the subpericardial areolar tissue of
1 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf.
THE LYMPHATIC GLANDS OF THE THORACIC WALL 813
the surface, and the latter in the subendocardial tissue. From the network of deep
lymphatics trunks pass to the superficial lymphatics. The superficial lymphatics
follow the course of the coronary vessels. Two trunks are formed: an anterior,
which lies in the anterior interventricular furrow, and an inferior, which lies in
the inferior interventricular furrow. These two trunks collect the lymph from the
ventricles and pass to the base of the heart, where they receive lymph from the
auricles. The anterior or left trunk ascends between the left auricle and the pul-
monary artery on the posterior surface of the artery, perforates the pericardium, and
enters the glands about the tracheal bifurcation. The right, posterior or inferior
trunk ascends between the aorta and pulmonary artery and terminates in the same
group of glands as the left trunk.
The Thymic Lymphatic Vessels. — The thymic lymphatic vessels arise from
the under surface of the thymus gland, and enter the anterior mediastinal, the
internal mammary, and the peritracheo-bronchial glands.
The Lymphatic Vessels of the (Esophagus. — The lymphatics of the thoracic
oesophagus arise from two networks, one beneath the mucous membrane and one
beneath the muscular fasciculi. The connecting trunks terminate in the peri-
cesophageal glands.
The Lymphatic Vessels of the Thoracic Trachea.— The lymphatics of the
thoracic trachea take origin from a network in the submucous tissue. From this
a number of collecting trunks pass through the trachea in the line of junction of
the cartilaginous with the membranous portion. They terminate the peritracheo-
bronchial glands.
THE NEKVE SYSTEM.
THE SPINAL CORD AND BRAIN, WITH THEIR
MENINGES.
REVISED AND LARGELY REWRITTEN, WITH NEW ILLUSTRATIONS.
BY EDWARD ANTHONY SPITZKA, M.D.,
PROFESSOR OP GENERAL ANATOMY, JEFFERSON MEDICAL COLLEGE, PHILADELPHIA.
THE nerve system of man is an apparatus by means of which he appreciates
and becomes influenced by impressions from the outer world, reacts on
these impressions, and hence is enabled to adapt himself to his environment.
It is the organic substratum for those manifestations of nerve force engaged in the
characteristic attributes of animal life — sensation and motion. Broadly stated,
the nerve system connects the various parts of the body with each other and
coordinates them into one harmonious whole in order to carry on the bodily
functions methodically and to control the physiological division of labor through-
out the organism. With the evolution of the higher forms of animal life through
an immense phylogenetic past the nerve system has undergone remarkable differ-
entiation and specialization, attaining its maximum as to dominant position and
complexity of structure in the human species.
The description of the nerve system is assisted by the accommodation of physio-
logical data to the anatomical basis in order to demonstrate more clearly and
to render more practical our knowledge of the mutual relations of its structure
and function. The cycle of events which accompanies nerve action is determined
by impressions received by the peripheral end-organs, apperception and reflexes
of these impressions in the lower nerve-centres, correlation of these with other
impressions in higher centres, as well as voluntary reactions or inhibitions, liber-
ated in compliance with the organic or higher needs of the individual.
Conventionally, the nerve system is usually considered as consisting of (1)
the cerebro-spinal system, comprising (a) the central nerve-axis (brain and spinal
cord) and (6) the peripheral nerves (cranial and spinal), and (2) the sympathetic
nerve system. This subdivision, like others formulated by various authors,
is an arbitrary one. No part of the system stands isolated, and the manifold
groupings and chainings of the units of the system intimately connect the central
nerve organs with the peripheral nerve-endings, the organs of special sense and
the vegetative organs. The distinction between the central and the sympathetic
systems has been too absolute, and the only justification for adhering to the
classification given above is based upon the fact that the sympathetic system is
preponderatingly related to the interconnection and coordination of the nutritive
(digestive, pulmonary, and vascular) apparatus, and, therefore, exercises a special
control over its activities.
(815)
816 THE NERVE SYSTEM
Structurally considered, the nerve system consists of cell-elements peculiarly
differentiated from all other tissue cells in that their protoplasm is extended, often
to great distances from the nuclear region, in the form of processes. The cell-
elements are held in place by supporting tissues, partly of ectodermal and partly
of mesodermal origin, and receive an abundant blood-supply.
The cell-element of the nerve system is called the neurone. The neurone is
the developmental, structural, and functional unit of the nerve system. It
is in reality a single cell presenting unusual structural modifications. It com-
prises not only the nerve cell-body with its numerous protoplasmic processes or
dendrites, but also the axone, which may vary in length from a fraction of a milli-
metre to fully half a man's stature; so that, despite the delicacy of the axone, its
bulk may be almost two hundred times greater than that of the cell-body from
which it proceeds. The long axones serve to make a connection with a peripheral
or distant nerve-cell, muscle-cell, or gland -cell, while the shorter axones of certain
neurones divide into terminal branches in the immediate vicinity of its cell-body,
presumably to come into relation with other nerve-cells in the same or adjacent
groups.
Neurones, being devoted to the maintenance of functions manifested by various
phenomena of nerve-force, are differentiated in their polarity, both structurally
and dynamically. Receptive neurones are so arranged as to receive afferent nerve-
impulses from other tissues; emissive or excitatory neurones give out efferent
nerve-impulses. The former are generally termed sensor neurones, the latter
motor (excito-motor) neurones if connected with muscle, excito-glandular if connected
with gland-cells. Were the nerve system made up solely of such initial and ter-
minal neurones the apparatus would be merely a system of reflex arcs. Such it
is in low forms of animal life which, by their very organization, and because
of the close juxtaposition of their sensory and motor elements, are compelled to
react to stimuli from without. In higher forms, with more profoundly differ-
entiated nerve systems, the sensory impression must pass through an interposed
medium which is capable of either transmitting the molecular change in the form
of an excito-motor impulse or, on the other hand, is capable of reducing or check-
ing the impulse. In other words, reaction is not imperative; there is a freedom
of choice exercised by intermediate neurones endowed with inhibitory function.
The simple arc, composed of an afferent sensory neurone and an efferent motor
neurone, would act independently of all other arcs were it not for the interposition
of this intermediate neurone and of other association neurones which, by their rela-
tions toward similar arc-elements, produce harmony of action. The basis, then,
of the nerve system is a series of neurones, with projecting and association pro-
cesses, coordinated for the purpose of performing specific actions manifested
either by motion, by trophic changes, or by the apperception of stimuli of a chemi-
cal, mechanical (tactile and auditory), thermal, or photic nature. When we con-
sider the profoundly complex manifestations of nerve-phenomena in the mental
and physical life of man it is not surprising to learn that his nerve system is
made up of an immense multitude of aggregations of neurones.
Fundamental Facts Regarding the Development of the Nerve System.—
The nerve system is formed by a remarkable metamorphosis of the ectodermic
layer of the developing ovum. Along the mid-dorsal line of the embryonic mass
a thickening of the ectoderm forms a well-defined layer of cells, the neural plate.
The proliferative process passes rapidly from the cephalic toward the caudal
end, and as development advances it is seen that the most intense growth-energy
takes place at the cephalic end, indicative of the higher functional potentiality
of what is to become the brain. The neural plate undergoes a trough-like for-
mation as its edges become elevated cephalad and laterally to form the neural
groove (Fig. 511). The edges become more and more elevated and bend toward
DEVELOPMENT OF THE NERVE SYSTEM
817
the median line until the margins of the groove coalesce to form a tube, the neural
tube, which sinks into the subjacent mesodermal tissues. The fusion of the mar-
gins of the neural plate occurs first in the cervical region and rapidly continues
both cephalad and caudad. The cephalic portion, destined to become the brain,
expands and grows considerably, while the caudal portion is chiefly elongated
to form the spinal cord.
NEURAL PLATES
NEURAL GROOVE
SOMATOPLE
PARAXIAL
MESOOERM
EIMTODERM
FIG. 511. — Diagrams showing development of neural tube and crest.
Eventually the neural tube, as it sinks into the subjacent mesodermal tissues,
severs all connection with the ectoderm from which it developed; but for a brief
period the continuity is preserved in an attenuated septal mass, the neural crest
(Fig. 51 1). The cell-elements of this crest subsequently become detached from the
superficial ectoderm, the continuity of which is again restored to form the integu-
NEURAL TUBE
L GANGLION
NOTOCHORD
VENTRAL ROOT
RAMUS COM-
MUNICANS
SPINAL NERVE
SYMPATHETIC
GANGLION
MESONEPHROS
r
MESENTERY
FIG. 512. — Diagram showing development of a spinal nerve and its components, together
with the spinal and sympathetic ganglia.
ment. They pass ventrad to either side of the neural tube, proliferate by mitosis,
and accumulate in paired masses, corresponding in number to the segments of
the body, to become, in part at least, the cerebro-spinal ganglion cells of the afferent
system, while other similarly paired masses migrate farther ventrad to a pre-
vertebral position to form the gangliated cord and widely spread plexuses of the
sympathetic system. From the tissues of the wall of the neural tube and its tem-
52
818
THE NERVE SYSTEM
porary crest the entire nerve system of complex and intricate structure is devel-
oped. The cavity of the tube shares in the developmental growth-changes to
become the ventricular system of the brain and central canal of the spinal cord.
The major details of the development of the principal divisions will be considered
in appropriate chapters.
Development of Nerve-tissue. 1. In the Wall of the Neural Tube.— The
single layer of nucleated epithelial cells of ectodermal origin which makes up the
wall of the neural tube early becomes modified into a layer of tall columnar cells
called spongioblasts (Fig. 513). Their protoplasmic ends undergo differentiation
in that the central ends become elongated and attenuated or collapsed to form a
series of striated pillars with intervening spaces. The free ends retain their
breadth, however, and form an internal limiting membrane. The ectal ends
undergo differentiation to form a spongy felt-work or reticulum (peripheral
veil of His); eventually these spongioblasts become (a) ciliated endymal cells
and (6) neuroglia.
— Germinal cell.
-Myelospongium
network.
FIG. 513. — Transverse section of the spinal cord of a human embryo at the beginning of the fpurth week.
Top of figure corresponds to lining of central canal. (After His.)
In the intercellular spaces of the central zone there appear spherical cells of
different structure and destiny. These are the germinal cells, seen in very early
stages and proliferating rapidly by karyokinesis. They soon lose their spherical
form, becoming pear-shaped as a protoplasmic process extends ectad. These
pear-shaped cells are now termed neuroblasts (Fig. 513), the protons of the neu-
rones, and as development advances they leave the central zone and migrate into the
marginal reticulum to the positions in which they are found in the gray substance
of the brain and spinal cord. The protoplasmic process is at first slightly bulbous
and elongates to form the axone extending toward other nerve-cells or to the
peripheral tissue-elements with which they become associated by the contiguity
of the terminal arborizations into which the bulbous extremity develops. The
precision with which the axones travel toward their allotted goal is one of the
most remarkable manifestations of organic development. An American experi-
menter, Ross G. Harrison, has devised a method for directly observing the living,
STRUCTURE OF THE NERVE SYSTEM
819
growing nerve. In isolated pieces of frog embryos the differentiation of the living
nerve-elements could be observed from day to day during several weeks. The
bulbous end of the outflowing protoplasmic fibre, showing a faint fibrillation, was
seen to reveal a continuous change of form particularly in a number of fine simple
and branched filaments which were in constant amoeboid movement. Harrison's
demonstration1 is of great significance in
connection with the "retraction theory"
and other ideas related to the neurone
doctrine.
2. In the Neural-crest Tissues. — The
nerve-tissue elements of the sympathetic
system and of the ganglia of the cranial
nerves and dorsal roots of the spinal nerves
are derived from the neural crest. Omit-
ting, for the present, the development of
the sympathetic system, it is found that
the cells of the paired masses which event-
ually become the cerebro-spinal ganglia
are at first somewhat spherical, then oval
in form, sending out from either extremity
or pole a protoplasmic process. One pro-
cess migrates centrad, the other toward the
tissues of the periphery. The central pro-
cess penetrates the tissues of the neural
tube and, assuming the typical form of
an axone with its collaterals and end
arborizations, comes into contiguous as-
sociation with certain cells of the cen-
tral axis. The peripheral process is in
reality an unusually long dendrite, for it
is centripetal in function; but owing to
the fact that it is usually provided with
a myelin sheath it is also termed the per-
ipheral axone of an afferent (or sensor) neu-
rone. The central processes of the cells of
a single spinal nerve-ganglion form the
dorsal nerve-roots; the peripheral pro-
cesses constitute the afferent portion of
a spinal nerve. The cells themselves are
transformed from bipolar into appar-
ently unipolar cells by the migration of
the cell-body to one side and the conse-
quent approximation of the two processes
to form a common pedicle in a T-shaped
manner (Fig. 535).
Structure of the Nerve System.—
The whole of the nerve system is com-
posed of nerve-tissue and supporting con-
nective tissue. The neurones constitute the nerve-tissue, while the supportive
tissue is composed of the neuroglia and of white fibrous tissue derived either
from the investing membrane or from the sheaths of its numerous vascular
channels.
FIG 514. — Scheme of central motor neurone. (I.
type of Golgi.) The motor cell-body, together with
all its protoplasmic processes, its axis-cylinder pro-
cess, collaterals, and end ramifications, represent
parts of a single cell or neurone, a.h., axone-hillock
devoid of Nissl bodies, and showing fibrillation;
c., cytoplasm showing Nissl bodies and lighter
ground-substance; n', nucleolus. (Barker.)
' American Journal of Anatomy, June 1. 1907, vii. 1. (Anatomical Record, p. 116.)
820
THE NERVE SYSTEM
The Neurone. — The neurone or nerve cell-element, whose individuality has
already been pointed out, exhibits remarkable variations as to external characters,
dimensions, and form. The neurone presents a concentrated or swollen cell-
mass and nucleus, formerly known as the nerve-cell (ganglion-cell) and still retain-
ing the name. From this cell- body are given off a number of processes of two dis-
tinct kinds: (1) protoplasmic processes which are commonly branched and gener-
ally called the dendrites; (2) a single, thinner, and paler process, the axone (axis-
cylinder process; Deiters' process; neuraxone; neurite).
Varied Forms of Neurones. — Bearing in mind that each neurone includes not
only the cell-body and its dendritic processes, but also the axone or axis-cylinder
process with all its ramifications, we
may consider each of these divisions
under separate heads.
1. Nerve Cell-body. External Mor-
phology.— The bodies of nerve-cells
vary much in size, measuring from
4 to 135 microns or more in diam-
eter. The largest cells are found in
the ventral horns of the spinal cord,
in the spinal ganglia, in the large
pyramidal cell-layer of the cerebral
cortex, in the Purkinjean cell-layer
of the cerebellum, and in the column
of Clarke (dorsal nucleus) of the
spinal cord. Very small cells are
found in the olfactory bulbs, in the
granular layers of the cerebral and
the cerebellar cortex, and in the
gliosum cornualis of the cord.
Although all nerve-cells begin in
the embryonic ectoderm as spherical
germinal cells, they later assume,
in different regions, very different
shapes. These external morpholog-
ical relations have been best revealed
by the methods of Ehrlich and'
Golgi. According to the number of
processes arising from the cell-body,
neurones are referred to as (1) uni-
polar, (2) bipolar, and (3) multipolar
nerve-cells.
(1) Unipolar cells are met with fre-
quently in early stages of embryonic
development, but are rare in the adult,
being found only in the retina, olfac-
tory bulb, and within the baskets
of the Purkinjean cells of the cerebellum. They are called amacrine cells. The
cells of the cerebro-spinal ganglia (excepting the cochlear and vestibular) are appar-
ently unipolar, but they are developmentally and functionally of bipolar nature.
(2) Bipolar cells are found almost exclusively in the peripheral sensor systems,
as in the olfactory membrane, in the retina, in the cochlear and vestibular ganglia,
and in the cerebro-spinal ganglia of the embryo.
(3) Multipolar cells are the most numerous and form the principal elements
of nerve-centres throughout the system. They are termed multipolar because
FIG. 515. — Showing some varieties of cell-bodies of neu-
rones (diagrammatic). A, unipolar (amacrine) cell from
the retina; B, bipolar cell from vestibular ganglion; C,
multipolar cell, with long axone, from spinal cord; D,
"Golgi cell" with short axone breaking up into numerous
terminal twigs; E, pyramidal cell from cerebral cortex.
a, axone; clt, collaterals; t, telodendria.
STRUCTURE OF THE NERVE XYtiTEM
821
of the greater or lesser number of dendrites given off in addition to the single
axone.1
The terms "unipolar" and "multipolar" must be restricted to the morphological
sense; dynamically all nerve-cells are bipolar.
According to the relations of the axone we distinguish, after Golgi, two kinds
of neurones.
I. Neurones with long axones which become the axis-cylinder of a central or
peripheral nerve-fibre. The axones give off several collaterals which, like the
parent stem, break into finely branched terminals or telodendria.
II. Neurones with relatively short axones which do not go into the formation
of a nerve-fibre, but break up into terminal twigs in the vicinity of the cell-bodies
from which they arise.
Type II is generally termed, for brevity's sake, the Golgi cell.
FIG. 516. — Purkinjean cell from human cerebellum, a, axone; clt, collaterals. (Golgi method.)
According to the morphological relations of the dendrites, neurones are classified
as follows:
(a) Stellate cells, the dendrites of which spring at intervals from the whole cir-
cumference of the cell-body and pass toward all directions (motor cells in ventral
horn and tract-cells of the cord).
(6) Cells with one principal stout dendrite (among other lesser dendrites)
which gives off side branches and ends in fine terminal twigs (pyramidal cells of
cerebral cortex; mitral cells of olfactory bulb).
(c) Arboriform cells, giving off branched dendrites from both base and apex,
resembling the roots and the branches of a tree; the axone often springs from
the base of one of the root-like dendrites (pyramidal cells of the hippocampus).
(d) Cells with monopolar dendrites. Several main dendritic stems spring from
one pole of the cell and, undergoing frequent subdivision, break up into a fine
terminal arborization. The axone springs from the opposite pole (Purkinjean
cells of the cerebellum; granular cells of the fasciola).
1 Exceptionally, more than one axone has been observed arising from a single cell, as in the Caial cells of
the cerebral cortex.
822
THE NERVE SYSTEM
2. Nerve Cell-body. Internal Morphology. — The nucleus of the nerve-cell differs
in no essential from the typical nuclear structure. Regarding the organization of
the cytoplasm several conflicting views exist. In the present state of our knowl-
edge concerning this still obscure field of investigation it may be said that the
nerve-cell protoplasm is roughly divided into a peripheral exoplasmic portion and a
central endoplasmic portion. There is shown throughout the cytoplasm a tendency
to fibrillary structure, more pronounced in the exoplasmic portion. Within the
meshes of a more or less homogeneous ground-substance, which pervades the
whole, are deposited larger and smaller masses of a granular substance. Nerve-
cells fixed and stained by the methods of Nissl and Held show that the granule-
masses are "stainable" (chromatophiles ; tigroid bodies; Nissl bodies), probably of
the nature of a nucleo-proteid (MacCallum) and looked upon as a sort of nutritive
reserve. Many of the larger cells possess more or less pigmented material, adja-
cent to the nucleus. The cells of the intercalatum (substantia nigra) and of the
locus cceruleus contain an abundance of such pigment-granules.
Axone.
•ath of
cell body.
'Nucleus.
Cell protoplasm.
FIG. 517. — Motor nerve-cell from ventral horn of
spinal cord of rabbit. The angular and spindle-
shaped Nissl bodies are well shown. (After Nissl.)
" Axone.
-Myelin sheath.
FIG. 518. — Bipolar nerve-cell from the spinal gang-
lion of the pike. (After Kolliker.)
The " unstainable" homogeneous ground-substance of the cytoplasm is probably
the more important functionally, for numerous delicate neuro-fibrils have, by special
methods, been shown to traverse the cell-body and its processes, crossing and
interlacing, perhaps anastomosing with each other, and traceable into the axone.1
Nissl, after years of painstaking investigation has classified nerve-cells into a great
many different species in accordance with their reaction to staining agents.
The Dendrites. — The dendrites are usually numerous attenuated processes
resembling in structure and staining reactions the cytoplasm and, being extensions
thereof, represent an increase in the surface of the cell-body. Emerging by a
broad base they become narrower as they divide into many branches in a dichot-
omous or arborescent manner to end free, according to most observers, or to be
joined with the dendrites of other neurones by means of minute fibrillse (as
claimed by Apathy) or by concrescence (Held). The contour of the dendrite is
usually irregular in some specimens, revealing varicosities along its course ; in others,
and more constantly, being seen to be beset with numerous lateral buds called
1 That the neuro-fibrils form such an intracellular network and that the axones arise therefrom is disputed
by Ramony Cajal, Bielschowsky, and others.
STRUCTURE OF THE NERVE SYSTEM 823
gemmules. Various hypotheses have been advanced in explanation of these
appearances, it being held by some investigators that they are related to conditions
of activity as contrasted to those of repose, while others believe them to be arti-
facts produced by the fixing and staining methods at present employed. How-
ever, it is no longer disputed that the function of the dendrites is receptive and
conductive (or cellulipetal) for nerve-impulses, although they probably serve the
nutritional requirements of the cell-body as well.
This functional distinction gives the clue to the correct interpretation of the
central and peripheral prolongations of the cerebro-spinal ganglionic neurones.
The cells of these ganglia are at first bipolar in form, but gradually undergo trans-
formation into apparently unipolar cells by the migration of the cell-body to one
side and the consequent approximation of the two processes to form a common
pedicle in a T-shaped manner so typical of the spinal ganglion cell of the adult.
The central branch invariably remains cellulifugal, the peripheral branch invaria-
bly remains cellulipetal, and as such is equivalent to the dendrites of all other neu-
rones. It is merely a modified dendrite in that it courses a longer distance without
branching until it reaches the periphery and is usually myelinic. Such a periph-
eral prolongation of the ganglion cell is also termed a centripetal nerve-fibre or
medullated (myelinic} peripheral axone of a peripheral centripetal neurone.
The Axone. — The axone is usually much longer than any of the dendrites, thin,
pale, smooth, emerging from the nerve-cell as a direct continuation of the neuro-
fibrillar ground-substance of the cell-body, and devoid, so far as at present known,
of chromatophile granules. Its calibre varies for the different cells, corresponding
in general to the length of its course, but it is practically of uniform diameter
throughout its extent. Axones may be extremely short or fully a metre in length.
Most cells give rise to only one axone (monaxonic neurones), but in certain localities
diaxonic (two axones) and polyaxonic (several axones) neurones are found. In a
Golgi preparation axones stand out like pieces of black thread, taking a more
direct course than do the irregular dendrites, and rarely branching before reaching
the ultimate termination, although giving off collaterals along their course. The
central axones of spinal ganglion (sensor) neurones are the principal exception
to this rule in that they bifurcate in a Y-shaped manner after their entrance into
the central nervous axis. In the case of another group of neurones, Golgi's Cell,
Type II, the axone is observed to break up into numerous branches soon after its
departure from the cell; such axones are called dendraxones. The axones and
their collaterals end in terminal arborizations, the telodendria.
The axone is the distributive or emissive (cellulifugal) conductor of nerve-
impulses. There is, therefore, a functional opposition attributable to the two
extremities of the neurone, based upon its dynamic polarity and upon a physio-
logical principle which is established by all experiments to which the nerve
system is submitted; namely, that nerve-impulses pass through the neurone in a
definite direction which is invariable and admitting of anatomical localization.
The majority of the peripheral spinal and cerebral axones as well as those
constituting the white matter of the brain and cord are invested by a myelinic
sheath.
The Collaterals (paraxones; cylindro-dendrites ; side fibrils). — The collaterals
are accessory branchings of the axones which are more numerous in the cyto-
proximal portion and are usually directed at right angles to the parent stem.
Some axones possess few or no collaterals, while others possess many. The col-
laterals, especially those in the gray substance of the central axis, are frequently
myelinic. They unquestionably play an important part in the grouping and
chaining of neurones within the system, in yielding up to neighboring neurones
a portion of the impulse that the cell has received by its dendrites and transmits
along its axone to a distance.
824
THE NERVE SYSTEM
Varieties of Axones. — Axones are divided into two main groups depending upon
the presence or absence of a myelin sheath — myelinic axones and amyelinic axones,
or medullated and non- medullated axones.
Myelinic axones or medullated axis-cylinder processes are axones enveloped by a
relatively thick sheath composed of semifluid phosphorized fat which gives to
the bundles of these structures their opaque, white appearance. The myelin
sheath is in turn invested by a delicate membrane (neurilemma) in one group,
while another group is devoid of such covering, giving rise to the further subdivision
into (a) myelinic axones with a neurilemma; (6) myelinic axones without a neuri-
lemma.
Myelinic axones with a neurilemma constitute the bulk of the cerebro-spinal
nerves and, in lesser proportion, of the sympathetic nerves. The myelin sheath
(medullary sheath of Schwami) does not invest the axone throughout its course nor
FIG.
treated
. 519. — A , myelinic axones in fresh state, showing a few internodes; B, portion of a myelinic axone
d with boiling ether and alcohol to remove the myelin and leaving the neurokeratin network; a, axone.
in a uniform manner. The axone after its emergence from the cell-body and
likewise in its preterminal portion is naked; and the delicate external membrane
or neurilemma comes in contact with the axone. The myelin sheath consists of
a number of tubular segments demarcated by nodal intersections which are only
0.08 mm. apart in the very small myelinic axones, while for larger axones the
intervals may be 1 mm. or more. At the internodes (nodes or constrictions of
Ranvier) the neurilemma dips into the constriction to come in contact with the
axone, and any branches of the axone are invariably given off at such points.
The interruptions in the continuity of the myelin sheath have been assumed to
be provisions facilitating nutritive diffusion between the axone and the surrounding
lymph. Each internodal myelinic segment is further characterized by oblique
clefts, irregularly distributed — the incisures of Schmidt-Lautermann — seen only
in fixed specimens and probably artifacts. Extraction of the fatty substance of
the myelin sheath by boiling alcohol and ether brings out a fine network which
NER VE-FIBRES AND NER VES
825
IN
INTERNODE
AXONE SHOWING
FIBRILLAR
STRUCTURE
resists trypsin digestion, and termed neurokeratin on account of its resemblance
to the keratin of epidermal structures.
The neurilemma (primitive sheath of Schwann; neurolemma), a delicate struc-
tureless membrane, encloses the myelin and the axone, wherever the myelin sheath
is wanting. Against the inner surface of the neurilemma, and embedded as it were
in the myelin, usually midway between
two nodes, lies the oval-shaped nucleus A B
of the neurilemma.
Myelinic axones are usually from 4
to 10 microns in diameter; the extremes
range from 2 to 20 microns.
Myelinic axones without a neurilemma
constitute the white substance of the brain
and spinal cord as well as the optic
nerves. They differ from the axones
just described in two particulars: the
neurilemma is absent and there are no
internodes interrupting the continuity of
the myelin sheath. A network of neu-
roglia replaces the neurilemma as a sup-
porting tissue.
Amyelinic axones with a neurilemma
(Remak's fibres; sympathetic nerve-fibres)
constitute the majority of the sympathetic
axones and the axones of the olfactory
nerves. The myelin sheath is absent and
the axone is invested, more or less com-
pletely, by a nucleated cellular sheath or
neurilemma.
Amyelinic axones without a neurilemma
are naked axones, most numerous in
the central ganglia. Most axones of
longer course are devoid of any sheath
in the cytoproximal and preterminal por-
tions, whatever investment they may re-
ceive in the intermediate portion.
1NCISURE OF
"SCHMIDT
-NEURILEMMA
NUCLEUS OF
-NEURILEMMA
NERVE-FIBRES" AND NERVES.
I U
Prior tO the general adoption of the Fio.520.-A, amyelinic axones with a neurilemma
neurone Concept it Was CUStomary tO only the nuclei of which can be seen; B, diagram
. ' i • 1 e i showing structure of amyelinic axone and illustrating
designate the Conducting elements Of the two views regarding the relations of the sheaths at the
, , _, internode (compare the two sides); C, trans-section of
nerve System by the term nerve-fibres a group of myelinic axones, stained with osmic acid,
i. ,. ,• f ,i ...ii,. A showing: NF, axonic neuro-fibrils; M, myelin; F,
in distinction from the nerve-cells. As endoneurium.
has been pointed out above, the distinc-
tion no longer holds, but the designation "nerve-fibre" is still retained in anatom-
ical vocabulary and recurs so frequently in common parlance that, even with the
new conception which has been formed of the architecture of the nerve system,
the term cannot yet be discarded in favor of ''axone," although it probably
will eventually.
Nerves are round or flattened bundles of axones which serve to bring the central
axis into relation with the periphery and other tissues of the body. The nerves of
the botlv are subdivided into two great classes-^the cerebro-spinal, which are
826 THE NER VE SYSTEM
attached to the cerebro-spinal axis, and the sympathetic or ganglionic nerves, which
are attached to the ganglia of the sympathetic. The cerebro-spinal nerves con-
sist of numerous nerve-fibres (myelinic axones) collected together into small or
large bundles or fasciculi and enclosed in a membranous sheath.
In structure the common membranous investment, or sheath of the whole nerve,
which is called the epineurium, as well as the septa given off from it, and which
separate the fasciculi, consists of connective tissue, composed of white and yellow
elastic fibres, the latter existing in great abundance. The tubular sheath of the
smaller fasciculi composing the nerve-trunk, called the perineurium, consists of a
fine, smooth, transparent membrane, which may be easily separated, in the form
of a tube, from the fibres it encloses; in structure it consists of connective tissue
which has a distinctly lamellar arrangement, being composed of several lamellae,
separated from each other by spaces containing lymph. The nerve-fibres are
held together and supported within the fasciculus by delicate connective tissue
called the endoneurium (sheath of Henle). It is continuous with septa which pass
inward from the innermost layer of the perineurium, and consists of a ground-
substance in which are embedded fine bundles of fibrous connective tissue which
run for the most part longitudinally. It serves to support the capillary vessels,
which are arranged so as to form a network with elongated meshes. The cerebro-
spinal nerves consist almost exclusively of myelinic axones, the amyelinic axones
existing in very small proportions.
The blood-vessels supplying a nerve terminate in a minute capillary plexus,
the vessels composing which pierce the perineurium and run, for the most part,
parallel with the fibres; they are connected together by short, transverse vessels,
forming narrow, oblong meshes, similar to the capillary system of muscle. Fine
amyelinic axones accompanying these capillary vessels, the vasomotor fibres,
and break up into elementary fibrils, which form a network around the vessel.
Horsley has also demonstrated certain myelinic fibres as running in the epineu-
rium and terminating in small bulboid tactile corpuscles or end-bulbs of Krause.
These nerve-fibres, believed to be sensor, and termed nervi nervomm, are con-
sidered to have an important bearing upon certain neuralgic pains.
Nerves, in their course, subdivide into branches, and these frequently commu-
nicate with branches of a neighboring nerve.
The axones, as far as is at present known, do not coalesce, but pursue an uninter-
rupted course from the centre to the periphery. In separating a nerve, however,
into its component fasciculi, it may be seen that they do not pursue a perfectly
insulated course, but occasionally join at a very acute angle with other fasciculi
proceeding in the same direction; from this branches are given off, to join again
in like manner with other fasciculi. It must be distinctly understood, however,
that in these communications the axones do not coalesce, but merely pass into the
sheath of the adjacent nerve, become intermixed with its axones, and again pass
on, to become blended with the axones in some adjoining fasciculus.
The communications which take place between two or more nerves form what
is called a plexus. Sometimes a plexus is formed by the primary branches of the
trunks of the nerves — as the cervical, brachial, lumbar, and sacral plexuses — and
occasionally by the terminal fasciculi, as in the plexuses formed at the periphery
of the body. In the formation of a plexus the component nerves divide, then join,
and again subdivide in such a complex manner that the individual fasciculi
become interlaced most intricately; so that each branch leaving a plexus may
contain filaments from each of the primary nerve-trunks which form it. In the
formation also of smaller plexuses at the periphery of the body there is a free
interchange of the fasciculi and primitive fibres. In each case, however, the
individual filaments or axones remain separate and distinct, and do not inosculate
with one another.
ORIGIN AND TERMINATION OF NER VES 827
It is probable that through this interchange of fibres the different branches
passing off from a plexus have a more extensive connection with the spinal cord
than if they each had proceeded to be distributed without such connection with
other nerves. Consequently the parts supplied by these nerves have more extended
relations with the nerve-centres; by this means, also, groups of muscles may be
associated for combined action, as is best exemplified in the formation of the
limb-plexuses.
The sympathetic nerves are constructed in the same manner as the cerebro-
spinal nerves, but consist mainly of amyelinic axones, collected into fasciculi and
enclosed in a sheath of connective tissue. There is, however, in these nerves
a certain admixture of myelinic axones, and the amount varies in different nerves,
and may be known by their color. Those branches of the sympathetic which
present a well-marked reddish-gray color are composed more especially of amye-
linic axones, intermixed with a few myelinic axones; while those of a white color
contain more of the latter and a few of the former. Occasionally, the gray and
white cords run together in a single nerve, without any intermixture, as in the
branches of communication between the sympathetic ganglia and the spinal
nerves, or in the communicating cords between the ganglia.
The nerves, both of the cerebro-spinal and sympathetic systems, convey impres-
sions of a twofold kind. The afferent or centripetal nerves, generally called sensor,
transmit to the nerve-centres impressions made upon the peripheral ends of their
components, to produce reflexes in the lower centres while the mind, through the
medium of the brain, becomes conscious of environmental conditions or changes.
The efferent or centrifugal (in large part "motor") nerves transmit impulses from
the centres to the parts to which the nerves are distributed ; these impulses either
excite muscular contraction or influence the processes of nutrition, growth, and
secretion.
The Ganglia may be regarded as separate small aggregations of nerve-cells,
connected with each other, with the cerebro-spinal axis, and with the nerves in
various situations. They are found on the dorsal root of each of the spinal nerves ;
on the sensor root of the trigeminus; on the facial and auditory nerves; and on
the glosso-pharyngeal and vagus nerves. They are also found in a connected
series along each side of the vertebral column, forming the gangliated cord or
trunk of the sympathetic; and on the branches of that nerve, generally in the
plexuses or at the point of junction of two or more nerves with each other or
with branches of the cerebro-spinal system. On section they are seen to consist
of a reddish-gray substance, traversed by numerous white nerve-fibres; they vary
considerably in form and size; the largest are found on the sensor root of the
trigeminus and in the cavity of the abdomen; the smallest, not visible to
the naked eye, exist in considerable numbers upon the nerves distributed to the
different viscera. The ganglia are invested by a smooth and firm, closely adhering
membranous envelope, consisting of dense areolar tissue; this sheath is continu-
ous with the perineurium of the nerves, and sends numerous processes into the
interior of the ganglion, which support the blood-vessels supplying its substance.
Origin and Termination of Nerves. — To the central and the peripheral
ending of a nerve are usually given the names of "origin" and "termination."
These designations have been rendered inappropriate, in many cases, by the newer
concept of neuronic arrangement. They have not yet become obsolete, however,
particularly in dissecting-room anatomy, and warrant description here with a
certain degree of reserve alluded to above.
Origin. — The origin in some cases is single — that is to say, the whole nerve
emerges from the nerve-centre by a single root; in other instances the nerve
arises by two or more roots, which come off from different parts of the nerve-
centre, sometimes widely apart from each other; and it often happens, when a
828
THE NER VE SYSTEM
nerve arises in this way by two roots, that the functions of these two roots are
different; as, for example, in the spinal nerves, each of which arises by two
roots, the ventral of which is motor and the dorsal sensor. The point where
the nerve-root or roots emerge from the nerve-centre is named the superficial or
apparent origin, but the axones of which the nerve consists can be traced for
a certain distance into the nerve-centre to some portion of the gray substance,
which constitutes the deep or real origin of the nerve.
The manner in which these fibres arise at their deep origin varies with their
functions. The centrifugal or efferent nerve-fibres originate in the nerve-cells
of the gray substance, the axones of these cells being prolonged to form the fibres.
In the case of the centripetal or afferent nerves the axones grow inward either from
nerve-cells in the organs of special sense (e. g., the retina) or from nerve-cells
in the ganglia. Having entered the nerve-centre, they branch and send their
ultimate twigs among the cells, without, however, uniting with them.
• fill ' - ^
~:\:V. .' •!'"'V^!*T ••".."• .'wt\>
FIG. 521. — Diagrams of motor nerve-endings in A, striated muscle; B, cardiac muscle; C, unstriated muscle
a, axone; t, telodendria. (After Huber, Bohm and Davidoff, and others.)
Termination. — Axones terminate peripherally in various ways and may be most
conveniently studied in the efferent and afferent systems respectively. The
so-called peripheral terminations of afferent neurones are better called peripheral
nerve-beginnings, on account of their functional relations; the impulse is excited
in the peripheral end and conducted centrad through the rest of the neurone.
Modes of Termination of Axones. — The ultimate terminals of the axones and their
collaterals are called telodendrions (or telodendria). As far as can be determined
by present methods they invariably end "free," commonly by exhaustion through
multiple division. This manifold branching presumably puts the neurone in a
condition to influence the processes of many other neurones ("avalanche conduc-
tion" of Ramon y Cajal). In some localities the formation by axonic terminals
of pericellular and peridendritic networks has been observed. Upon muscle-
fibres the axone terminals form chains of flattened disks, the motor end-plates.
Among gland-cells the terminal fibrils form more or less intricate plexuses.
Peripheral Nerve-beginnings of Centripetal Neurones.— Nerve-beginnings of the
centripetal (sensor) fibres are found in nearly all the tissues of the body. They
ORIGIN AND TERMINATION OF NERVES
829
are peculiarly differentiated and of various forms in different localities and their
function is apparently the conversion of mechanical, thermal, chemical, and other
stimuli into nerve-impulses. The organs of vision, hearing, smell, and taste possess
variously modified nerve-beginnings which are described under appropriate titles
in the chapter on the Organs of Special Sense. The end-organs of the centripetal
neurones collecting bodily impressions (tactile sense, muscular sense) and con-
nected with the central axis are often very complicated structures. The prin-
cipal varieties are:
f Terminal fibrillae.
Tactile corpuscles (Meissner's).
"Ruffini's endings."
I. \ Lamellated corpuscles (Pacini's).
Bulboid corpuscles (Krause's).
Genital (nerve) corpuscles.
Articular (nerve) corpuscles.
II.
f Neuro-muscular spindles (Ruffini).
( Neuro-tendinous spindles (Golgi).
D
FIG. 522. — Showing some var
beginnings"): A, terminal fibr
Dogiel); C, bulboid corpuscle (Krause's, after Dogiel); D, lamellated corpuscle (Pacini's, after Dogiel,
Sala, and others); E, genital nerve corpuscle from human glans penis (after Dogiel); a, axone; t, telodendria.
830
THE NERVE SYSTEM
Terminal Fibrillse are best demonstrable in the epithelium of the skin, mucous
membranes, and cornea. The axone is seen to break up into its constituent
fibrilhe, which often present regular varicosities and anastomose with each other
in a plexiform manner.
Tactile Corpuscles (corpuscula tactus; touch corpuscles of Meissner and Wagner]
consist of elongated oval lobules of delicate epithelioid tissue invaded by one or
more axones which divide into their primitive fibrils, each terminal branch ending
free usually as a somewhat flattened, disk-like plate in among the wedge-shaped
cells of the corpuscle. Tactile corpuscles occur in large numbers in the cutaneous
papillne of the finger-tips, in the conjunctiva, and, less abundantly, in the rest of
the skin ; they appear to be concerned with the finer tactile sensations.
Ruffini has described a special variety of sensor nerve-beginning in the sub-
cutaneous tissue of the human finger (Fig. 523). They are principally situated at
the junction of the corium with the subcutaneous tissue; they are of oval shape,
and consist of a strong connective-tissue sheath within which the axone divides
into numerous varicose fibrils ending in small, free knobs.
Lamellated Corpuscles (corpuscula lamellosa; Pacinian corpuscles; Vater's
corpuscles; Herbst's corpuscles) are among the largest of the tactile end-organs
and are found chiefly in the palmar surface of the hand, the sole of the foot, the
genital organs, the serous membranes, and many other structures. Each corpuscle
Axones.
Terminal ramifications
of axones.
FIG. 523. — Nerve-ending of Ruffini. (After A. Ruffirii, Aich. ital. de Biol., Turin, 1894, t. xxi.)
consists of a number of capsular connective-tissue lamellae arranged more or less
concentrically around a central granular protoplasmic core, pierced by a single
axone which usually divides into two or more branches giving off collaterals of
beaded appearance and terminating in rounded knobs.
Bulboid Corpuscles (corpuscula bulboidea; Krause's end-bulbs) are minute cylin-
drical or oval bodies, consisting of a capsule continuous with the perineurium
enclosing a core (inner bulb) of semifluid, finely granular protoplasm in which an
axone runs out to end quite free at the distal end, usually terminates in a bulbous
extremity, or, as is frequently observed, the axone divides into a number of
branches of which each one terminates in an end-bulb.
The genital corpuscles (corpuscula nervorum genitalia) and the articular corpuscles
(corpuscula nervorum articularia) very much resemble the bulboid corpuscles
just described.
The genital corpuscles form aggregations of from two to six knob-like masses
in the penis and clitoris. The articular corpuscles are found in the synovial
membranes of the joints.
Neuro-muscular Spindles (muscle-spindle of Kuhne) . — These are found in nearly
all the skeletal muscles and are most numerous in the extrinsic muscles of the
tongue, in the small muscles of the hand and foot, and in the intercostal muscles.
Most elaborate investigations upon these spindles have been conducted recently
by Ruffini in Italy, Sihler, Huber, and De Witt in America. Neuro-muscular
ORIGIN AND TERMINATION OF NERVES
831
spindles are usually found in the fibrous septa of the perimysium and consist of
the flattened nerve-fibrils of centripetal axones arranged in one or all of three
ways: (1) annular, where the fibrils surround the muscle-fibres in rings; (2)
spiral, and (3) dendritic or branched (Fig. 524). They are doubtlessly concerned
with the so-called muscle-sense.
Dendritic branchings
Rings.
Spirals./
FIG. 524. — Middle third of a terminal plaque in the muscle-spindle of an adult cat. (After Ruffini.)
Neuro-tendinous Spindles (Organ of Golgi). — The nerves conveying sensory
impulses from the tendons have a special modification of the terminal fibres, in
the form of numerous fibrils with branching end-plates or of an annular and spiral
arrangement resembling the neuro-muscular spindles. They usually occur at
the junction of the tendon bundles with the muscle-fibres (Fig. 525).
Organ of Golgi, showing
ramification of nerve-fibrils.
Muscular fibres.
FIG. 525. — Neuro-tendinous spindle organ of Golgi from the human tendo calcaneus (Achillis).
Tendon bundles.
(After Ciaccio.)
The Neurone Doctrine. — The results of the investigations of Golgi, Cajal, Forel,
and others prompted Waldeyer to enunciate a theory with regard to the nerve
mechanism of the neurone. This hypothesis is generally known as the neurone
theory and assumes that (1) each neurone is a distinct and separate entity; (2)
the collaterals and other terminals of the neurone form no connections among
themselves; (3) neurones are associated, and impulses conveyed, by contact or
contiguity of the axonic terminals of one axone with the cell-bod v or dendrites of
832
THE NERVE SYSTEM
another neurone. The theory postulates a nerve-cell amrebism analogous to the
extension and retraction of the pseudopodia of an amoeba, and the "retraction
theory" has been propounded in explanation of certain functional dissociation
phenomena attending nerve-force manifestations.
Opposed to the "neurone theory" or "contact theory" is the more recent
continuity theory which is being earnestly advocated by Apathy, Bethe, and Nissl.
In behalf of this theory it is claimed that the neurofibrils are continuous not only
within the cell and its processes, but through an extracellular network as well.
The dispute now being waged does not, however, affect our fundamental ideas
regarding the individuality of neurones with regard to their dynamic condition.
The Supporting Tissue Elements of the Nerve System.— A fine meshwork
of non-nerve tissue, more or less dense in different localities, but apparently
restricted to the central axis, serves to support the neurones. This sustentacular
tissue is of two kinds: (1) the neuroglia; (2) connective-tissue trabeculae derived
from (a) the pia or (6) vascular channels.
FIG. 526. — Neuroglia-cells of brain shown by Golgi's method: A, cell with branched processes; B, spider-
cell with unbranched processes. (After Andriezen.) (From Schiifer's Essentials of Histology.)
The Neuroglia. — The neuroglia consists of glia-cells of varied forms and glia-
fibres. Glia-cells are divisible into two species: endymal cells and astrocytes of
long-rayed and short-rayed type.
Endymal cells are the columnar epithelial cells which line the neural canal
throughout. In the embryonic condition each cell is seen to project a long multi-
branched filament toward the periphery of the neural tube, while the free end
carries a tuft of cilia. In adult life both the cilia and the radial filament are
apparently lost or very much reduced.
Regarding the structure of the glia-cells proper as well as of the glia-fibres there
is a variance of opinion among different investigators. The astrocytes, as they
are commonly revealed in Golgi preparations, may, as pointed out by Weigert
and others, be due to an extension of the silver deposit upon glia-cell nuclei as
well as upon adjacent filaments. Huber,1 Hardesty,2 and others regard neuroglia
tissue as a syncitium resulting from an early fusion of the protoplasm of the cells
of the neural tube which at first were individual and definitely bounded. The
filamentous reticulum of glia-fibres ordinarily seen in adult tissues seems to result
1 American Journal of Anatomy, 1901, pp. 45-61.
2 Ibid., 1904, pp. 229-268.
THE CENTRAL NERVE SYSTEM 833
from an increase of the fine threads of the spongio-plasmic network of the original
cell-protoplasm. Neuroglia occurs in both gray and white substance as an
all-pervading supporting tissue. In certain localities, as upon the surface of the
brain and cord, the neuroglia tissue is disposed in the form of a thin layer.
Besides the neuroglia, the central nerve system contains as supporting tissues
numerous fine and coarse septa or trabeculse derived from the investing pia, or
from the sheaths of blood-vessels.
Chemical Composition. — The amount of water in nerve-tissue varies with the
situation. Thus in the gray substance of the cerebrum it constitutes about 83 per
cent., in the white substance from the same region about 70 per cent., while in
the peripheral nerves, such as the sciatic, it may fall to 60 per cent.
The solids consist of neuro-albumins, neuro-globulins, nucleo-proteins, neuro-
keratin (in the gray substance proteins constitute about one-third of the total
solids), lecithins, cerebrosides (chiefly phrenosin), cholesterin, unidentified organic
sulpho-compounds, amino-fatty substances, nitrogenous extractives and inorganic
salts, with some collagen, fat, etc., in the adherent connective tissue (W. J. Gies).
THE CENTRAL NERVE SYSTEM.
The central nerve system, as it is conventionally distinguished from the sympa-
thetic system, is composed of a central axial aggregation of ganglia forming the
brain and spinal cord, which are connected with the other tissues of the body
by 43 pairs of nerves, of which 12 pairs are attached to the brain and 31 pairs
to the spinal cord. The functional relations of the central mechanisms with the
periphery are maintained by the essential cell-elements of the nerve-tissues, the
neurones. The chief task in the study and analysis of the structure of the nerve
system lies in the dovetailing of features visible to the naked eye with those
visible only under high magnifying powers. By the combination of macroscopic
with microscopic features the attentive student is enabled to resolve or recon-
struct, in the three dimensions of space, and see with his mental eye the opaque
interior transparently resolved into intricate yet well-defined projecting and asso-
ciating mechanisms. Assistance in such study may be derived from illustrations
depicting hidden structures in accordance with this principle.
Preliminary Considerations. Gray Substance and White Substance. — The cen-
tral axis of the nerve system contains two categories of substance, their difference
to the eye being one of color. They are conventionally designated the gray and
white substance. The white substance (alba), which forms about two-thirds of the
neuraxis, is the conducting substance and its characteristic appearance is due to
the myelin sheaths which invest the axones in it. The gray substance (cinerea;
grisea) is the sentient and reacting mass containing the cell-bodies of neurones.
Its color is due to its translucency, its greater vascularity, and to a certain
amount of pigmented material in the cell-elements. The white and the gray
substance is not sharply demarcated everywhere, for although the white substance
is exclusively conducting substance, the gray is not exclusively ganglionic, for
the former encroaches on the latter; in some localities, as in the ventral horns of
the spinal gray, in parts of the cerebral cortex, in the reticular formation of the
pons and oblongata, and in the column of Clarke (dorsal nucleus), the admixture
of myelinic fibres is considerable. Both white and gray substance is pervaded
by the neuroglia.
The specific gravity of the cortical gray is 1.021, of the great ganglia 1.034,
of the gray substance in the cerebellum and mesencephalon 1.050, and of the
white substance 1.028.
For convenience of study, and somewhat in correspondence with phyletic
53
THE NERVE XY8TEM
development, the central axis of the nerve system is divided into (1) the spinal
cord and (2) the brain, grossly sub-divided into (a) oblongata, pons, and cerebellum;
(6) mid-brain and (c) fore-brain. This gross subdivision is arbitrary and the inter-
relations of the parts would be obscured were too much stress laid upon any mode
of separation.
THE SPINAL CORD (MYELON; MEDULLA SPINALIS).
The spinal cord is the attenuated, nearly cylindrical part of the cerebro-spinal
axis which lies in the vertebral canal, occupying its upper two-thirds in the adult.
It extends from about the level of the
atlo-occipital articulation (or lower
border of the pyramid decussation) to
the level of the lower border of the
body of the first lumbar vertebra,
where it terminates in a slender fila-
ment of gray substance enveloped by
pia, and, further caudad, by a sheath
N.CERV. I.
LIGAMENTUM
DENTICULATUM
FIG. 528. — Ventral view of nblongata and upper
part of spinal cord. Dura and arachnoid cut along
FIG. 527. — Showing the relation of the spinal cord to median line and folded aside. A and K are fairly
the dorsal surface of the trunk. The vertebra are constant velar folds of the arachnoid. (After Key
.shown in red outlines. and Retzius.)
of dura which is attached to the dorsum of the coccyx. The spinal cord is
continuous cephalad with the oblongata. Its length is 45 cm. (44 to 50 cm.)
in the male and 43.5 cm. (39.5 to 47 cm.) in the female. In the course of
foetal development, the spinal cord occupies the entire length of the vertebral
canal up to the third month, but after this period it gradually recedes cephalad
owing to the more rapid growth of the vertebral column, so that at birth the
caudal end of the spinal cord has risen to the level of the third lumbar vertebra.
The spinal cord does not entirely fill the vertebral canal. A wide space, or
rather a concentric series of spaces intervene between its surface and the walls
THE SPINAL CORD
835
of the canal, affording a marked freedom of movement of the vertebral column
without exerting undue tension upon the spinal cord. These spaces, three in
.number, which concentrically surround the cord, are demarcated by the three
protective membranes: (1) pia, (2) arachnoid, and (3) dura, which are continuous
with the like meninges of the brain. The arrangement of the spaces and the
membranes may be shown thus:
t .
—
c ~
-t-i -•
i it
1
Epidural
space.
Subdural
space.
Subarachnoid
space
and
subarachnoid
reticulum.
•2 PH
The pia closely invests the entire surface of the spinal cord and sends septal
ingrowths into its substance as well as a fold occupying the ventro-median
fissure. A leaf-like, serrated fold of pia, the ligamentum denticulatum, passes
from each lateral border to the inner surface of the dural sheath and helps to
support the cord within the subarachnoid space. The arachnoid and the pia
are not separable in gross dissection as they merge insensibly, though usually
described as distinct membranes. The arachnoid is in reality an exceedingly
delicate and transparent web-like reticulum whose meshes constitute a relatively
wide cavity filled with cerebro-spinal fluid. The dura constitutes the outermost
and thickest sheath, while the narrow interval between the dura and the vertebral
canal is filled by a fine venous plexus, together with soft, areolo-fatty tissue.
Of the three spaces which surround the cord, only the two innermost contain
fluid, and that of a serous character; the amount in the sub-dural space is very
small, just sufficient to moisten the contiguous endothelial surfaces of the dura
and arachnoid; that in the slib-arachnoid space is considerable. (For detailed
description see section on the Meninges.)
Weight. — The weight of the spinal cord, exclusive of all nerve-roots, averages
2S grams, or 1 ounce avoirdupois, being slightly less in the female. Including the
nerve-roots as ordinarily cut in postmortem procedure, the weight averages 45
grams in the male and 40 grams in the female. The ratio of weight in proportion
to that of the brain is1 lowest in the human species, being 1 to 51 in the male and
1 to 49. S in the female. In the newborn the ratio is 1 to 115. Its specific gravity
is 1.038.
External Morphology. — In situ the spinal cord exhibits slight curvatures in the
sagittal plane, being convex ventrad in the transition from cervical to thoracic
portion and slightly concave ventrad to the lumbar portion. Its position varies
also according to the degree of curvature of the spinal column, being raised
slightly (a few millimetres only) in flexion of the spine.
836
THE NER VE SYSTEM
The intrinsically segmental nature of the spinal cord is expressed by the asso-
ciation of each definite segment with the somatic segment supplied by its nerves.
Thirty-one pairs of spinal nerves are commonly enumerated, although two addi-
tional, rudimentary pairs, relics of a tailed vertebrate ancestry, are demonstrable
microscopically.
The first pair of spinal nerves emerges
between the occiput and atlas, and is
designated the first cervical; the other
cervical pairs are named after the lower
of the two vertebra which form the in-
tervertebral foramen through which the
nerve emerges. Very inconsistently the
pair emerging between the seventh cervical
and first thoracic vertebra is called the
eighth cervical pair. The remaining
XII. THORACIC
V. LUMBAR
I. SACRAL-
COCCYGEAL-
FIG. 529. — Showing the relations of the cord
and nerve origins to the levels at which the nerves
emerge through the intervertebral foramina (dia-
grammatic).
FIG. 530. — The cauda equina exposed within
its dural sheath.
spinal nerves are named after the upper of the two vertebra forming the corre-
sponding foramen. In all there are:
Cervical pairs 8
Thoracic pairs 12
Lumbar pairs 5
Sacral pairs 5
Coccygeal pairs 1
31
THE ENLARGEMENTS OF THE SPINAL CORD
837
C.I.
C.2.
C5.
All spinal nerves are made up of two roots by which they spring from the lateral
aspects of the cord, symmetrically arranged, and these nerve-root attachments
are the only guides to the demarcation of the
various segments of the spinal cord. The two
roots are generally termed the dorsal (afferent or
sensor) root, which enters the cord along the
dorso-lateral fissure and the ventral (efferent or
motor) root which emerges along the ventro-lateral
fissure.
Although the cervical nerves pass outward
through the intervertebral foramina at nearly a
right angle to the long axis of the cord, those of
the lower series slope more and more downward,
so that the fifth lumbar pair emerges six verte-
bral bodies lower than it originates. In fact,
the lumbar and sacral nerves descend as parallel
bundles in a brush-like manner to form the cauda
equina, enclosed by the dural sheath as far as
about the middle of the sacral canal. The topo-
graphical relations of the levels of origin and
exit of the spinal nerves to the spinous processes
of the vertebra is shown in Fig. 529.
Corresponding with the degree of development
of the periphery, the spinal cord is more mas-
sive in those segments which are associated with
the limb. Thus, in the ground-mole, the cervical
portion is very much enlarged in conformity with
the powerfully developed fore-limbs, while in the
kangaroo or the ostrich, with powerful legs, the
lumbar portion of the spinal cord is proportion-
ately enlarged. In man, both the cervical and
lumbar portions are enlarged, and while the bulk
of the lower limbs exceeds that of the upper, the
cervical portion of the spinal cord is more redun-
dant because it innervates a limb which is func-
tionally more differentiated, capable of much more
skilful and complex movements and endowed with
more acutely developed tactile sensibility.
The Enlargements of the Spinal Cord. — The
spinal cord is marked by two spindle-shaped en-
largements in its cervical and lumbar portions,
while the intervening thoracic portion is nearly
cylindrical, being slightly reduced in its dorso-
ventral diameter. The cervical enlargement (intu-
mescentia cervicalis) extends from the first or
second cervical segment to the level of the second
thoracic vertebra, acquiring a maximum breadth
(13 to 14 mm.) at the sixth cervical vertebra. At
its junction with the oblongata its breadth is about
11 mm. The thoracic portion is about 10 mm.
in breadth (minimum at a little below its mid-
dle) while its sagittal diameter is 8 mm. The
lumbar enlargement (inlumescentia lumbalis) be-
gins at the level of the tenth thoracic vertebra, FlG-
C.8.
Th2.
Th.8.
Th.12.
L.3.
S.2.
Coc.
spinal
838
THE NERVE SYSTEM
PYRAMIDAL
DECUSSATION"
VENTRO-LATERAL
GROOVE
DORSO-PARAMEDIAN
"FISSURE
^CERVICAL
'ENLARGEMENT
DORSAL
"GROOVE
DORSO-LATERAL
"FISSURE
acquires its maximum breadth (12 mm. ; sagittal diameter = 9 mm.) opposite the
twelfth thoracic vertebra Below the lumbar enlargement the cord gradually
tapers to form a cone (conus),
the apex of which, at the level
of the lower border of the body
of the first lumbar vertebra, is
continuous with the attenuated
filum.
The cervical enlargement is
characterized by a relatively
greater breadth than the re-
maining portions of the cord
which, on section, appear nearly
circular.
Conus (conus medullaris] . —
The conus is the conical ex-
tremity of the cord. The Iow7er
three sacral segments and the
coccygeal segment are usually
included under this term. Its
diameter becomes reduced to
2 mm., to be continued below as
the filum.
Filum (filum terminate; ner-
vus impar). — The delicate ter-
minal thread called the filum,
continuous with the tapered end
of the conus, is about 24 cm. in
length. As far as the level of
the second sacral vertebral seg-
ment it is enclosed, together
with the cauda equina, in the
tapering sheath of the dura.
Within the dural sac it is called
the filum internum, in contradis-
tinction to the filum externum,
which is an attenuated process
of connective and nerve-tissue
invested by a prolongation of
the dura, which finally attaches
to the periosteum of the dorsum
of the coccyx. The filum ex-
ternum occupies one-third of
the total length of the filum.
Morphologically, the filum is
the caudal representative of the
cord, and its intradural portion
is usually accompanied by slen-
der fascicles of nerve-fibres,
which are rudimentary second
and third coccygeal pairs of
spinal nerves.
Fissures and Grooves. — The
FIQ. 532^;r:^^ZS and its fissures. spinal cord is a bilaterally sym-
.LUMBAR
ENLARGEMENT
or rni-: CORD
839
metrical structure and exhibits a deep ventral fissure and a slight dorsal groove
partially subdividing the cord into right and left halves. The ventral fissure
extends throughout the entire length of the eord, being shallower in the cervical
and dorsal portions (less than one-third of the sagittal diameter) than in the
lumbar portion. It is lined by a fold of pia which conveys the more important
nutritive vessels to the depths of the cord substance. In the depth of this fissure
lies the white ventral commissure of the cord. The dorsal groove has been re-
garded, erroneously, as being analogous to the ventral fissure. Unlike the ventral
fissure, however, the pia does not descend into its depths, but passes continuously
over it. The shallow groove marks the site of a septum made up of neuroglial
and endymal elements. An actual groove is best demonstrable in some of the
lumbar cord and in the oblongata, where it constitutes a veritable fissure between
the clavse.
Each lateral half is marked by the lines of root-attachment of the spinal nerves.
The dorsal nerve-root fascicles enter the cord in linear series and in a depression
or true sulcus termed the dorso-lateral fissure. The ventral nerve-root fascicles
jSs.
&
Dorsal nerve root
Central canal.
— Nuclei of spongio-
blasts.
euroblasts.
C^Jv Processes of neuroblasts
^ — growing out to form
anterior nerve root.
-Ventral column
Fin. 533. — Section of spinal cord of a four weeks' embryo. (His.)
emerge, irregularly scattered, out of a greater circumferential area and no true
ventro-lateral fissure can be said to exist. The line of emergence of the outermost
fascicles is usually taken as an arbitrary boundary between the ventral and lateral
districts of the cord, while the dorso-lateral fissure more distinctly maps off the
lateral from the dorsal district. An additional fissure, observed most distinctly
in the cervical and upper thoracic portions, termed the dorso-paramedian fissure,
demarcates the two principal divisions of the dorsal columns, the dorso-median
and the dorso-lateral columns. The dorso-paramedian fissure is an exceedingly
shallow groove and is best denoted in sections of the cord by its continuance as a
connective-tissue (glia) septum into the substance of the dorsal column. An analo-
gous ventro-paramedian fissure is sometimes observable close to the ventral fissure,
demarcating the ventral (or direct) pyramidal fasciculus.
Columns of the Cord (funiculi medullae spinalis). — Each half of the spinal
cord is thus divided, with respect to its white substance, into three chief columns
or funiculi. The dorsal column occupies the area between the dorsal septum and
groove and the line of attachment of the dorsal nerve-roots; this column in its
turn is generally subdivided into the dorso-median (funiculus gracilis; column of
840
THE NER VE SYSTEM
Goll} column and the dorso-lateral (funiculus cuneatus; column of Burdach) by
the shallow dorso-paramedian groove and glia-septum referred to above. The
ventral column (funiculus anterior) occupies the area between the ventral fissure
DORSAL ROOT
SOMATIC SENSOR
VISCERAL SENSOR
VISCERAL MOTOR
SOMATIC MOTOR
FIG. 534. — A diagram of the component elements in the spinal cord and the nerve-roots in a trunk-segment
to illustrate the four functional divisions of the nervous system. (After Johnston.)'
and the outermost fascicles of the ventral nerve-roots — an arbitrary boundary
line. The lateral column (funiculus lateralis] constitutes the remainder of the
cord, between the dorsal and ventral nerve-root attachments. Each of these
PER PHERAL
SPONGIOBLAST
GERMINAL CELL
NAL QANGLION
GERMINAL CELL
;>ERIPHERAL
'ROCESSES
NEUROBLAST-
AXONES OF VENTRAL
NERVE-ROOTS
FIG.' 535. — Trans-section through neural tube, early and later stages, diagrammatical. Earliest stages
shown on left side. On the right, the maturing neuroblasts are seen sending their axonic processes toward
ths periphery or to other regions of the central axis, and the central processes of the spinal ganghomc
calls are seen to invade the dorso-lateral region.
columns is subdivided into its component bundles or fasciculi, best studied in
sections of the cord.
Development of the Spinal Cord. — The elongated postcranial portion of the
neural tube becomes the spinal cord, while the primitive cavity within is preserved
841
as the central canal of the cord. The metamorphosis of the neuro-epithelial
columnar cells has been described (p. 818). The lateral walls thicken considerably,
the central slit-like canal widens as the walls bulge outward in an angular manner,
and the central tubular gray becomes a fluted column with dorsal and ventral
ridges (or horns) enveloped by a rapidly growing mantle of axone bundles which
LOCATION OF THE SEGMENTS FOR
SENSIBILITY. MOTILITY.
Thoracic and abdominal
viscera
Occipital region
Front of neck
Back of
Shoulder
IXuiculo-
spiral n.
Median n.
Ulnar n.
Navel
Inferior abdominal refl<
Sphincter iridis
Giliaris
Rectus int., levator palpebr. sup.
Rectus inf. and sup.
Obi. infer.
— Obi. super.
Masseter, temporal, pterygoids
Rectus extern.
Occipitofront., orbicularis oculi (upper facial'
Muscles of expression (lower facial)
Palatal and pharyngeal muscles
Muscles of the larynx
Muscles of the tongue
Sternocleidomastoid
Deep muscles of the neck
Scaleni
Trapezius, serratus anticus
Diaphragm
Delt., biceps, pectoral, maj. (clavic. portion) 1 ^
Srachial. antic., supinator longus
Triceps, latis. dorsi,pect. maj. (costal " ))»
' Extensores carpi et digitorun
Flexores carpi et digitorum
Interossei, lumbricales •>
Thenar, hypothenar j
Intercostal!
Muscles nf the back
Abdominal muscles
* Forearm
— — lliopsoas -\
Sartorius I
— Adductors f
— •• Abductors J
ThigK
Leg
Scrotum, penis, etc
Bladder, rectum
~ Quadriceps f
Flexors > Leg
Extensors )
Peronei
Flexors, extensors of the foot and toes
Glutei (f)
Perin
Vesical \ Musculature
Rectal
FIG. 536. — Explanation of abbreviations: tr. olf., olfactory tract; c. g. I., lateral geniculate body; p, r, cr. A,
indicate approximately the location of the reflex centres for the pupillary (p), the respiratory (r), cremas-
teric (cr), patellar (pat), and tendo-Achillis (A) reflexes. The vesical centre lies in the third and fourth
sacral segments; the anal centre in the fourth and fifth (represented by circles); the centres for erection,
ejaculation, Ijibor pains (?) are probably also situated in this region. In reality, the divisions between the
various segments are, of course, not so sharp as they are shown in the diagram, so that a given muscle or
cutaneous region derives some of its controlling nerve-roots from the segments lying immediately above
and below ths principal segment. The sensor segment for any given region is regularly somewhat higher
than the corresponding motor segment. (Jakob.)
become myelinic in successive stages. The bulging of the thickening walls in the
dorsal and ventral as wrell as lateral directions produces the ventral fissure and the
post-septum.
The segmental nature of the spinal cord has been alluded to before with regard
to the segmental derivation of the cerebro-spinal ganglia and the disposition of the
out-growing nerve-bundles. There is a further mode of division into longitudinal
842
THE NERVE SYSTEM
systems based upon functional relationships. Two main categories of activity
characterize the mechanism of the nervous system and find somatic expression in
its architectural plan: First, actions in relation to the external world (somatic —
involving skin, muscle, skeleton, etc.); second, internal activities concerned with
the processes of nutrition and reproduction (visceral — involving the alimentary
tract, circulatory, excretory, and reproductive systems). In each there is a twofold
activity on the part of the nerve system: reception of stimuli and motor responses.
In the cord (and to some extent in the brain as well) the following functional
divisions may be distinguished and located anatomically (Fig. 534) :
Ventral aspect. Dorsal aspect.
FIG. 537. — Distribution of cutaneous nerves.
Somatic sensor elements.
Somatic motor elements.
Visceral sensor elements.
Visceral motor elements.
This functional differentiation of the neural axis into sensor and motor divi-
sions apparently finds organic expression in an important modification of the
developing neural tube Each lateral wall of the neural tube is early demarcated
INTERNAL STRUCTURE OF THE SPINAL C<H;i>
into a dorsal and a ventral strip or lamina and the slit-like central canal becomes
more or less lozenge-shaped on trans-section, owing to the formation of a lateral
longitudinal furrow within. The dorsal lamina or zone is preponderatingly
sensor in function, while the ventral zone is principally motor in function. This
fundamental fact has been of the greatest aid in the correct interpretation of many
hitherto obscure facts regarding the mechanism of the nerve system, and will
be found to underlie our method of description throughout.
Muscular Supply from Motor Segments of the Cord. — This is shown in
Fig. r>36.
Internal Structure of the Spinal Cord. — If a transverse section of the spinal
cord be made, it will be seen to consist of white and gray nerve substance.
The white substance is made up of myelinated axones; the gray contains the cell-
bodies of neurones and non-myelinated axones. The color of the gray substance,
so called, varies according to the degree of capillary injection and the age of the
individual. It is usually of a faint reddish-gray tinge, the gray preponderating in
older persons, but various shades of red, yellow, and light-slate color may be noted.
DORSAL GROOVE
DORSAL SEPTUM
DORSAL ROOT
DORSO-LATERAL
FISSURE
RETICULAR
FORMATION
LATERAL HORN
VENTRAL HORN
FIG. 538. — Trans-section of the spinal cord at the mid-thoracic region.
Nor is the color uniform even in the same section. Around the central canal and
at the periphery of the dorsal horn the gray substance is very translucent and
is termed, according to its situation, the gliosa centralis (gelatinosa centralis)
and gliosa cornualis (gelatinosa Rolandi or caput gliosum}. The white substance
surrounds the gray column as a variously thickened tunic, closely invested by the
pia, which sends numerous delicate, vessel-bearing ingrowths into the substance of
the cord. The relative area of the white substance, as seen on section, increases
cephalad ; the absolute area of both white and gray is largest in the region of the
enlargements (Fig. 539).
Gray Substance of the Cord (nitocinerea; substantia grisea centralis). — A
plastic conception of the gray substance of the cord is essential to an understand-
ing of the internal architecture. The gray core must be imagined not alone in the
relations in which it is conventionally studied, as exposed in trans-sections, but
also as a fluted column having a continuous extent throughout the cord. This
gray column, is drawn into ventral and dorsal ridges, connected respectively
with the ventral and dorsal nerve-roots, while the white substance fills out the
844
THE NERVE SYSTEM
irregularities and completes the nearly cylindrical outline of the cprd (Ficrs
540 and 541).
On viewing a trans-section, it is seen that the gray substance is so arranged as to
present, in each lateral half of the cord, a crescentic or comma-shaped mass, the
concavity of which is directed laterad. The two lateral masses are connected
by a transverse bar or band of gray substance, termed the gray commissure (com-
missura cinerea [grisea]), and containing the central canal, which extends the
entire length of the cord. The dorsal septum of the cord reaches quite to the
gray commissure, there being but a few white commissural fibres in the dorsal
zone. Ventrad, however, a lamina of
white substance, the commissura ventralis
alba, separates the gray commissure
from the ventral fissure (Fig. 538) .
In trans-sections of the cord it is
seen that the lateral crescentic gray
masses, united across the middle line
by a gray commissure, have the aggre-
gate appearance of the letter H. Each
crescentic mass presents projections
which are more or less pronounced
according to the segment of the cord
FIG. 539. — Projection upon a plane of the absolute
and. relative extent of the gray and white substance
of the cord as determined by successive sectional
areas. Gray substance shown in black. (Adapted
from the measurements of Stilling.)
FIG. 540. — Formation of a spinal nerve.
(Testut.)
under consideration. Broadly stated and without reference to special levels, the
most marked projections are the dorsal and ventral horns or cornua.
The Dorsal Horn, directed dorso-laterad , is elongated and narrow, and its apex
is composed of a translucent V-shaped mass termed the gliosa cornualis (caput
gelatinosa Rolandi [caput gliosum would be a better term]).
The attenuated apex of the dorsal cornu approaches the surface of the cord
along the line of entrance of the dorsal nerve-roots. The apex of the dorsal horn
is wider in the regions of the enlargements and the gliosa is most marked in
the higher cervical segments. The base or cervix of the dorsal horn is constricted
somewhat except in the thoracic portion, where its greater breadth is due to the
presence of the nucleus dorsalis (Clarke's column}.
The Ventral Horn is shorter, thicker, and more blunt, and is separated from the
ventral and lateral surfaces of the cord by a tolerably thick lamina of white
INTERNAL STRUCTURE OF THE SPINAL CORD 845
substance. Its margin, in trans-sections, presents a dentate or stellate appearance
due to the emergence of fascicles of efferent or ventral root-axones on their way to
the ventral surface of the cord.
\Vhat is known as the lateral horn projects as a lateral peninsular extension of
the central gray nearly on the line of the gray commissure. It is best marked as
a triangular projection in the upper thoracic segments. In the cervical enlarge-
ment it is merged with the greatly expanded ventral horn, but it again becomes
prominent in the upper cervical segments.
The gray substance of the cord is not everywhere sharply demarcated from the
white owing to the invasion of myelinic and amyelinic nerve-fibres. Facing the
lateral column, in the angle between the dorsal and ventral horns, small fascicles
of white fibres are embedded in the gray so that it is broken up in a peculiar basket-
work pattern termed the reticula or reticular formation. This gray network is
best marked in the cervical region and becomes more abundant in the oblongata.
The mode of arrangement of the gray substance and its amount in proportion to
the white vary in different parts of the cord. Thus, the posterior horns are long
and narrow in the cervical region ; short and narrower in the thoracic ; short but
wider in the lumbar region. In the cervical region the crescentic portions are
DORSAL RO
VENTRAL FISSURE
FIG. 541. — Showing origin of two pairs of spinal nerves (schematic).
small, and the white substance more abundant than in any other region of the
cord. In the thoracic region the gray substance is least developed, the white
substance being also small in quantity. In the lumbar region the gray substance
is more abundant than in any other region of the cord. Toward the lower end of
the cord the white substance gradually ceases. The crescentic portions of the
gray substance soon blend into a single mass, which forms the only constituent
of the extreme point of the cord.
The Gray Commissure which connects the two crescentic masses of gray substance
consists of myelinic and amyelinic nerve-fibres and neuroglia. The fibres pass
transversely, spreading out at various angles, into the lateral gray masses. In
the gray commissure, and extending the whole length of the cord, is a minute
channel, the central canal (myelocele; canalis centralis), which is barely visible to
the naked eye, but is proportionately larger in some of the lower vertebrates.
Cephalad, in the oblongata, it opens out into the fourth ventricle; caudad it is
continued for a short distance into the filum, in which it ends blindly. The canal
is very minute, less than 0.1 mm., except in the terminal part of the conus, where
it expands into a fusiform dilatation, the sinus terminalis (rhombocaele; veutriculus
terminalis [Krause]). The central canal is lined by a layer of columnar cells which
THE NERVE SYSTEM
are seen to be ciliated in the embryo and are in all respects identical with the
endymal cells lining the ventricles of the brain. Surrounding the endymal lining
DOHSO-LATERAL.
GROUP
INTERMEDIATE
CROUP
VENTRO-LATEHA
GROUP
DORSO-MEDIAL
"GROUP
VENTRO-MEDIAL
"GROUP
DORSAL NUCLEUS
(.CLARKE)
INTERMEDIATE
GROUP
DO RSO- LATERAL-
GROUP
VENTRO-LATERAL
GROUPS
VENTRO-MEDIAL
"GROUP
INTERMEDIATE
GROUP
F-ic.. 542. — Trans-sections of the spinal cord at different levels to show the topographical arrangement
of the principal cell-groups.
of the central canal and gradually merging into the spongy substance which con-
stitutes the remainder of the gray commissure is a finely granular and reticulated
INTERNAL STRUCTURE OF THE SPINAL CORD 847
substance, the gliosa or gelatinosa centralis, almost entirely composed of neuroglia,
with a few fine fibrils apparently proceeding from the endymal cells, and having a
translucent, gelatinous appearance.
The gray substance of the cord is composed of (1) the gliosa, which envelops
the head of the dorsal horn and which encircles the central canal of the cord ; (2)
the spongiosa, which forms the crescentic horns (except the heads of the posterior
horns and the envelope of the central canal). Further, it may be stated that the
gray substance consists of nerve-fibres of variable but smaller average diameter
than those of the white column ; (3) nerve-cells of various shapes and sizes, with few
or many processes; (4) blood-vessels, lymphatic channels, and connective tissue.
The nerve-fibres of the gray substance of the posterior horn are for the most part
composed of a dense interlacement of minute fibrils, intermingled with nerves
of a larger size. This interlacement is formed partly by the axones and dendrites
of the cells of the gray substance, and partly by fibres which enter the gray substance
and which come from various sources.
The nerve-cells of the gray substance are collected into groups as seen on trans-
verse section, but they really form columns of cells placed longitudinally; or else
they are found scattered throughout the whole of the gray substance (Fig. 542).
In the ventral horn four main groups of cells may be distinguished which are
not wholly represented, however, in all regions of the cord: (1) A ventral group
of cells, separable in the cervical and lumbar regions into ventro-medial and ventro-
lateral sub-groups; (2) a dorso-medial group, situated in the cervix of the ventral
horn, usually demonstrable in the thoracic portion as well as a few contiguous
cervical and lumbar segments; (3) a lateral group, separable in the lower cervical
and lumbar regions into ventro-lateral and dorso-lateral sub-groups, and supplying
the muscles of the extremities; (4) a central group of cells in the lumbar and sacral
regions.
In the lateral horn, which is most prominent in the thoracic and upper cervical
segments, lies an intermediate group of cells, a long, slender column which is
nearly restricted to the thoracic portion of the cord, but is seen to reappear in the
upper three cervical and in the third and fourth sacral segments. The axones
from these cells probably do not pass out with the ventral nerve-roots, but rather
course within the cord to terminate at various levels on the same as well as on
the opposite side. A close connection with the sympathetic nerve system, and
with vasomotor and sweat-gland nerves, has been suggested.
In the dorsal horn the most conspicuous group of cells is a columniform nucleus
commonly termed Clarke's column (nucleus dorsalis), which extends between the
seventh cervical and second (or third) lumbar segments of the cord. The cells
are large and the group presents an oval outline in trans-sections, lying in the medial
part of the cervix of the dorsal horn. The axones of these cells pass out of the
gray into the lateral column of the cord to form the spino-cerebellar tract, and
convey tactile impulses to the cerebellum.
Just ventrad of Clarke's nucleus, and extending through a greater length of
the cord, scattered cells constitute the nucleus of Stilling, represented in the
oblongata by the accessory cuneate nucleus. Aside from these nuclear columns,
the cells of the dorsal horn are not grouped very definitely, and for the purposes
of description they are sub-divided according to their location. The cells vary
much in form and size and their branched axones pass toward other regions
within the gray substance at various levels on the same or on opposite sides, or via
the ground-bundles. Many fibres of the dorsal nerve-roots are in relation with
the dorsal-horn cells.
The various groups of cells enumerated above are frequently demarcated from
neighboring groups by nerve-fibre intervals which may be straight, curved, inter-
laced, or loop-shaped.
848
THE NERVE SYSTEM
\
CERVICAL
NUCLEUS
DIRECT
SPINO-CEREBELLAR
TRACT
Through the gliosa cornualis pass numerous fine fibrils, chiefly the afferent
dorsal nerve-root fibres, but in addition this peculiar, gelatinous, a-nd semitrans-
lucent substance contains numerous small stellate cells; the region is so densely
filled with axones and collaterals, as well as neuroglia-cells that until stain ing-
methods became sufficiently developed the importance of this substance remained
in dispute. In man the gliosa cornualis shows convolutions feebly imitating
those of the olive, and its structure is analogous. Dorsad of the gliosa lies the
ultimate zone of the dorsal horn ; this gray substance resembles the spongiosa in its
essential characters.
The White Substance of the Cord (substantia alba). — The white substance of the
cord, consisting chiefly of longitudinally disposed myelinic fibres, with blood-vessels,
neuroglia, and connective-tissue septa, forms
a thick mantle which invests the central
gray column. When stained with carmine,
a transverse section of the white substance is
seen to be studded all over with minute
dots surrounded by unstained circular areas.
The dots are the transversely cut axones ;
the lighter areas are the myelin sheaths. The
mass of white substance is closely invested
by a sheath of neuroglia immediately be-
neath the pia. Numerous septa, derived from
the pia, but always coated by a thin layer
of neuroglia, pass into the white substance
to separate the respective bundles of fibres
and are often interwoven between individual
nerve-fibres, acting as a supporting frame-
work in which they are embedded. In ad-
dition to the longitudinal fibres there are
shorter and less numerous transverse fibres
collected into the so-called ccmmissural bundle
or white commissure.
Longitudinal Fibres. — The longitudinal
fibres constitute the conducting tracts. Al-
though a purely anatomical examination
fails to reveal the functional relations of
these fibre-bundles, the structural alterations
which ensue (in accordance with the laws
of Waller) in the distal portion of a. neurone
whose proximal portion has been destroyed,
the progressive myelinization of separate
tracts in the embryo and infant (as proved
by the researches of Meynert and Flechsig),
the comparative anatomy method and electro-physiological experimentation have
rendered possible the demonstration of the origin and destination of the various
conducting systems or tracts with almost mathematic accuracy. While some fibres
pursue a lengthy course, serving as conduction paths between the brain-centres and
the various spinal centres, others are shorter and serve to associate different spinal
levels — in juxtaposition or relatively not far distant. It must be borne in mind
that the gray substance, intercalated as it is in the course of the impulses which pass
to and fro in the cord, contains the neural elements which are either (a) the source
or (6) the destination of these impulses, and thus complete the nerve-cycle
requisite for the organization of the functions belonging to the cord. The motor
and sensor phenomena, though interacting, depend upon distinct nerve elements
DORSAL NUCLEUS
"(CLARKE'S COLUMN)
j / SACRAL
[T~NUCLEUS
FIG. 543. — Showing the dorsal nucleus (of
Clarke), and its cervical and sacral extensions
on one side, and the direct spino-cerebellar tract
on the other. The fibres of the tract ascend on
the same side as the nucleus in which they arise.
INTERNAL STRUCTURE OF THE SPINAL CORD 849
which, because of their functional relationship, or because of the direction in
which they convey impulses, are generally referred to as motor or sensor, efferent
or afferent neurones; and in the spinal cord usage has sanctioned the employ-
ment of the terms descending and ascending for tracts conveying motor and sensor
impulses, respectively. Anatomically speaking, however, it is preferable to- de-
scribe the tracts with reference to their origins and termini (as cerebro-spinal,
spino-thalamic, etc.), when known, or to their topographical relations as studied
in trans-sections of the cord.
For the purposes of description it is convenient to classify the longitudinal
fibres into three general systems: (1) The cerebro-spinal system of axones
forming conduction paths for efferent impulses from the cerebrum to the
spinal centres for peripheral organs, and axones for afferent impulses received
in the spinal centres from the periphery and conveyed in turn to the cerebrum.
(2) The spino-cerebellar system, consisting of conduction paths, afferent and
efferent, between the cerebellum and the spinal centres. (3) Numberless asso-
ciation systems strictly confined within the cord (or only extending into the
oblongata), composed of shorter or longer axones which serve to associate not only
different levels of the same spinal segment, but also the different segments, that
are in juxtaposition or more remotely situated. These spinal association axones
form bundles in close contact with the central gray column and are termed the
fasciculi proprii or ground-bundles.
The columns of white substance have already been enumerated (p. 839) as the
dorsal, lateral, and ventral columns or funiculi.
In the dorsal column there are described the following tracts :
Ascending:
(1) Fasciculus gracilis (Golli) .
(2) Fasciculus cuneatus (Burdachi) .
Descending:
(1) Comma tract (Schultze) .
(2) Median oval tract (Flechsig).
Associating:
(1) Fasciculus dorsalis proprius.
(2) Dorsal cornu-commissural tract.
(3) Septo-marginal tract (Bruce).
Another tract, usually described as belonging to the lateral column, but func-
tionally more intimately related to the sensor neurone-system of the dorsal
column is the fasciculus marginalis (of Spitzka and Lissauer).
The great majority of the axones constituting the dorsal column are the afferent
(sensor) axones arising from the spinal ganglion cells, entering the cord by the
dorsal roots. These dorsal root-axones bifurcate in the region of the dorsal
horn, one branch ascending a little obliquely at first, then vertical, while the other
branch takes a similar downward course for a shorter distance (Fig. 544).
As additional groups of fibres are contributed by each successive dorsal nerve-
root the mass of white substance in the dorsal column accumulates as the cord is
ascended, though it must be noted that not all of these afferent fibres traverse the
whole of the cord above, but end in relation with cells in the gray substance at various
levels. The successive accessions of afferent fibres are disposed in a laminated
manner so that the lumbar fibres come to lie laterad of the sacral bundle, the
thoracic laterad of the lumbar, and so on as the cord is ascended. A section
of the cord at its highest level would therefore traverse a collection of bundles
derived from all of the dorsal-nerve roots of the cord, arranged as shown in Fig. 544.
In the upper segments of the cord it is possible to distinguish a division of the
dorsal column into two principal fasciculi owing to the presence of a distinct
connective-tissue septum which passes into the substance of the dorsal column
54
850
THE NERVE SYSTEM
along the dorso-paramedian groove. These fasciculi are termed, according to
their position, the dorso-median and dorso-lateral fasciculi or Goll's column and
SULCO-MARGINAL TRACT
FOR PREGEMINUM
VENTRO-MARGINAL TRACT
FROM FASTIGIUM (LoWCntlial's)
SIXTH
THORACIC
THIRD
LUMBAR
WHITE VENTRAL COMMISSURE
FIG. 544. — Sections of the spinal cord at the level of the sixth cervical, sixth thoracic, and third lumbar
segments, the conducting tracts being indicated on the right side of each section: C, comma tract of Schultze;
H, spino-olivary tract of Helweg; M, marginal tract of Spitzka-Lissauer; O, oval field of Flechsig.
Burdach's column; in the consideration of the external morphology of the cord,
these have already been referred to as the funiculus gracilis and funiculus cune-
atus, respectively.
INTERNAL STRUCTURE OF THE SPINAL CORD
851
It has been noted that even in the fresh cord, when sectioned, the gracile bundle
has a different tinge and stains more deeply with carmine than does the cuneate
bundle.
The caudad or descending branches of the bifurcate dorsal-root axones are
considerably shorter than the ascending branches. They terminate in the gray
substance in relation with its cells and, by numerous collaterals which are shorter or
larger and given off at various intervals, serve to associate different levels of the
cord. Some of these collaterals cross the median line in the dorsal commissure
to come into relation with neurones of the opposite side. Certain of the longer
D.R
D.R
D.R"
D.R;
FIG. 545. — Ramifications of the central processes (axones) of afferent neurones entering the spinal cord as
seen in longitudinal section (schematic) : D. R., axones of dorsal roots; 6, their bifurcation; clt, collaterals;
t, telodendria ending in proximity of cells in the gray matter; F, C., axones of gracile and cuneate fasciculi.
descending branches show a tendency to collect into a feebly marked bundle along
the mesal border of the dorso-lateral fasciculus, called because of its outline in
trans-sections — as seen in cases of descending degeneration from injury at a higher
level — the comma tract of Schultze. A similar bundle, situated along the dorsal
septum, best demonstrable in the lumbar cord, and with its fellow of the opposite
side of oval outline as seen on section, is called the oval bundle of Flechsig (tractus
cervicolurribalis [Edinger]; dorsomediales Sakralfeld [Obersteiner] ).
Marginal Tract. — Not all the axones of the dorsal-nerve root enter the dorsal
column. Another group elsewhere described passes into the dorsal horn as
852 THE NERVE SYSTEM
well as toward Clarke's column, while a third group of fibres forms the so-called
marginal tract,1 situated close to or among the entering fibres of the dorsal roots,
but frequently described as lying in the lateral column. The tract is demonstrable
in all levels and is made up of successive increments of relatively short axones
(traversing not more than three or four segments) to end in relation with the cells
of the gliosa cornualis. It has been assumed that the tract is concerned with
the transmission of pain-sense.
Ground-bundle of the Dorsal Column. — A zone of fibres contiguous with the
dorsal face of the gray column, and termed the fasciculus dorsalis proprius or dorsal
ground-bundle, is composed of axones arising from the smaller cells of the dorsal
horn, which, after entering the white substance and bifurcating into ascending
and descending branches, come into relation with other levels of the gray column
by means of collaterals and terminating in it after a comparatively short course.
They are therefore to be regarded purely as association or "longitudinal com-
missural" fibres. The dorsal cornu-commissural tract (ventrales hinterstrangs-
biindel [Striimpell]; zone cornucommissurale [Marie] ), occupying a triangular
interval at the apex of the trans-sected dorsal column, and the septo-marginal
tract [of Bruce], in apposition with the post-septum, belong to this category of
association bundles. Both tracts are most evident in the lumbar portion of the
cord.
In the lateral column the following tracts may be enumerated :
Ascending:
(1) Dorso-lateral spino-cerebellar tract (Flechsig).
(2) Superficial ventro-lateral spino-cerebellar tract (Gowers) .
(3) Spino-thalamic tract.
(4) Spino-mesencephalic tract.
(5) Spino-olivary tract (Hellweg).
Descending:
(1) Crossed pyramidal tract.
(2) Rubro-spinal tract.
(3) Cerebello-spinal tract (Marchi and Lowenthal).
(4) Vestibulo-spinal tract.
(5) Olivo-spinal tract.
Associating:
(1) Fasciculus lateralis proprius.
The dorso-lateral spino-cerebellax or direct cerebellar tract (of Gratiolet and
Flechsig) lies at the periphery, laterad of the crossed pyramidal tract. Its
axones arise from the cells of Clarke's column and ascend uninterruptedly to
the oblongata. and thence to the vermis of the cerebellum in its post-peduncle.
The tract becomes more massive as the cord is ascended (Fig. 543).
The superficial ventro-lateral spino-cerebellar tract also courses along the per-
iphery, but farther ventrad. The origin of its axones is yet in dispute; they prob-
ably arise frorn cells in the gray column of both sides, in the zone between the
dorsal and ventral horns as well as from some of the ventral-horn cells. The
destination of the axones of this tract is equally uncertain, but most of the fibres
have been traced through the dorso-lateral region of the oblongata and the pontile
reticula, whence it turns dorsi-mesad, to enter the cerebellum through the valvula
and ending in the dorsal vermis. A lesser portion of the tract has been traced to
the quadrigemina, while other groups of axones end in various levels of the
gray column.
The spino-thalamic and spino-mesencephalic (iractus spinotectalis) tracts are
not gathered into compact bundles, but are rather scattered among the fibres of
1 First described by E. C. Spitzka (in 1885) and Lissauer (1886) and usually bearing the name of the latter.
INTERNAL STRUCTURE OF THE SPINAL CORD 853
the lateral column just mesad of the superficial ventro-lateral spino-cerebellar
tract (Gowers). The axones of both systems arise from cells in the dorsal horn
and its cervix of the opposite side, coursing through the white ventral commissure
and ascending the cord, the spino-thalmic fibres ending in the thalamus, the
spino-mesencephalic fibres ending in the region of the quadrigemina. The two
tracts are collectively called tractus spino-tectalis et thalamicus.
The spino-olivary tract (Helweg's Dreikantenbahn; Bechterew's Olivenbiindel)
is found only in the higher segments of the cord, at its periphery and just laterad
of the emergence of the ventral nerve-roots.
Its connections and functional direction are uncertain; some investigators have
traced its fibres between the olive and certain ventral-horn cells; Obersteiner
suggests a relationship with the pyramidal tract. The coincidence, in point of
time, of the myelinization of both tracts is significant in this connection.
The crossed pyramidal tract (lateral cerebro-spinal fasciculus) occupies an
approximately triangular or oval area in the dorsal portion of the lateral column,
just mesad of the direct cerebellar tract, except in the lumbar cord, where it lies
at the surface. The axones of this tract arise from the pyramidal cells of the
cerebral cortex (motor area) of the opposite side. After having descended
through the internal capsule, crusta, pons, to the pyramis of the oblongata, the
major portion of the fibres derived from one-half of the brain decussate with those
of the other half, crossing the median line to descend in the lateral column of the
cord. The fibres which do not decussate constitute the direct pyramidal tract
in the ventral column. As the crossed pyramidal tract descends it diminishes in
size as its axones become distributed to the ventral horn, where they terminate in
contiguity with the ventral motor cells which give rise to the fibres of the ventral-
(motor) nerve roots. The bundle becomes exhausted as a distinct strand at the
level of the fourth sacral segment.
The rubro-spinal, cerebello-spinal, lateral vestibule-spinal, and olivo-spinal tracts
consist of descending axones which are intermingled so that their mutual topo-
graphical relations cannot at present be described. Collectively they constitute
the fasciculus intermedius of Lowenthal and Bechterew (intei -media-lateral tract
of Bruce and Campbell) and they lie ventrad of the crossed pyramidal tract and
mesad of the combined spino-thalamic and spino-mesencephalic tracts.
The rubro-spinal tract (Monakow's tract; prepyramidal tract) originates in the
rubrum (red nucleus in the tegmentum of the mid-brain) of the opposite side and
its axones terminate in relation with ventral-horn cells. In their course these
fibres are seen to invade the area of the crossed pyramidal tract.
The cerebello-spinal tract (Marchi's tract) is supposed to arise in the cortex of
the cerebellar hemispheres, to become distributed to the motor centres in the
ventral horn.
The lateral vestibulo-spinal tract arises in the lateral nucleus of the vestibular
nerve (Deiters' nucleus) and by its relations with spinal centres establishes a
connection with the equilibratory apparatus.
The olivo-spinal tract, according to Kolliker, is a crossed tract whose axones
arise in the olive and terminate in relation with the motor cells of the ventral
horn.
Several other descending tracts ending in the spinal cord and arising in higher
centres like the quadrigemina, central gray of the mesencephalon, and the cere-
bellum have been recently described by Held, Boyce, and Bechterew.
Ground-bundle of the Lateral Column (fasciculus lateralis proprius). — This lies
in the concavity of the lateral aspect of the gray column and consists of axones
having a purely commissural function. In the regions where the reticula is best
marked it is subdivided into a group of smaller bundles by numerous glial
septa.
854 THE NER VE SYSTEM
In the ventral column are described the following tracts :
Descending:
(1) Direct pyramidal tract.
(2) Sulco-marginal tract.
(3) Ventral vestibulo-spinal tract.
Associating:
(1) Association-axones between spinal centres and several cranial nerve
nuclei.
(2) Fasciculus ventralis proprius.
The direct pyramidal tract (fasciculus cerebrospinalis ventralis; fasciculus of
Tiirck) is the uncrossed portion of the pyramidal tract below the decussation in
the oblongata, and constituting only 10 to 15 per cent, of the fibre system arising
in the motor cortex of the same side. It is a small, oblong bundle, as seen on
trans-section, lying parallel with the ventral fissure, from which it is separated
in the higher segments by the relatively narrow sulco-marginal tract. The tract
diminishes in bulk as the cord is descended, to disappear in the thoracic portion
of the cord ; though, in rare instances, it has been observed to extend throughout
the lumbar portion as well. This diminution and eventual disappearance of
the tract is due to the successive decussations of its fibres throughout its course,
for, with a few exceptions, these cross in the ventral white commissure to come
into relation with the ventral-horn cells (motor cells) of the opposite side. This
partial longitudinal extension of the pyramidal decussation and consequent
formation of an uncrossed, ventrally situated pyramidal tract is peculiar to the
primate order of vertebrates.
The sulco-marginal tract (tractus tectospinalis) is a thin bundle whose axones
arise in the quadrigemina of the opposite side, immediately decussating and
descending through the oblongata, to be distributed to various spinal centres in
a manner not yet accurately ascertained. The system is assumed to be concerned
in the coordination of movements of the head, with optic and acoustic reflexes.
The ventral vestibulo-spinal tract (Lowenthal's tract; anterior marginal fascic-
ulus; ventral cerebello-spinal tract} lies at the periphery of the ventral column,
extending, as seen on trans-section, from the ventral-root zone to the ventral fissure.
Its axones arise from (1) the lateral (I)eiters') and (2) superior (Bechterew's)
nuclei of the vestibular nerve; (3) from the fastigatum of the cerebellum. Their
termination about the ventral-horn cells has been traced as far as the sacral region
of the cord.
As in the lateral column, and continuous with the like formation, there is in the
ventral column an intermediate zone of mixed systems of axones which serve to
associate various levels of the cord with ganglionic masses in the oblongata as
well as with the cerebellum and quadrigemina. The nuclei of the trigeminus,
facial, auditory, glosso-pharyngeal, and vagus nerves, together with the olive
and the cerebellum, seem most intimately associated with the spinal centres for
movements of the head and neck.
Ground-bundle of the Ventral Column. — The white substance of the ventral column
contiguous with the central gray is made up of intersegmental axones of associa-
tion connecting different levels of the cord.
The ventral white commissure (commissura ventralis alba] is composed of mye-
linic fibres which decussate with or cross each other and, on trans-section, are
seen to form a narrow band connecting the ventral columns of the two sides. The
axones composing it are chiefly (1) those arising from ventral-horn cells, which
after crossing the mid-line, course horizontally or cephalad and caudad to come
into relation with neurones at the same or at different levels of the gray substance;
(2) the decussating axones of the direct pyramidal tract; (3) numerous collaterals
from the ventral and lateral column axones. The white commissure is most
INTERNAL STRUCTURE OF THE SPINAL CORD
855
massive in the enlargements where the associations of the limb-centres are neces-
sarily greater in number.
Myelinization of the Axones of the Cord. — The acquisition of the myelin sheath
is not contemporary for all axones in the cord, but is characterized by a regular
progression in the myelinization of separate fasciculi. As a rule, those axone
systems which are concerned with simpler or intrinsically spinal reflexes become
myelinic or "mature" at an earlier stage of fetal development than do those con-
cerned in the more elaborate connections of the cord with the brain. Thus, the
efferent and afferent axones, and those of associating neurones, become myelin-
ated in the fifth and sixth months of foetal life, while the pyramidal tracts and the
spinp-olivary tract (of Helweg) are observed to be the last to mature at the time
of birth, in correspondence, apparently, with the inception of the functional use
of these tracts. The order of myelinization of the separate fasciculi is indicated
in Fig. 546.
FIG. 546. — Diagram showing the order of myelinization of the various tracts in the spinal cord (cervical
level). The tracts are named on the right side; the Roman numerals on the left side correspond with the
enumeration given in the text. H, Helweg's tract; M , marginal tract.
Summary. The Gray Substance. — The gray substance consists, aside from its
supporting tissues, of sentient and reacting nerve-cells, with their dendrites and
axones, and of the terminals of axones entering from without. These nerve-
cells may be classified as follows:
(a) Nerve-cells whose axones pass directly out of the cord. These lie in the
ventral horn, are "motor" in function, and their axones form the ventral-nerve
roots.
(6) Nerve-cells whose axones pass into the white substance, usually bifurcating
into a shorter descending and a longer ascending branch. Two kinds of cells
are distinguished :
1. Strand- or tract-cells whose axones (ascending branches) traverse the cord,
to come into relation with higher centres in the brain.
2. Association-cells whose axones, after a comparatively brief course in the
white substance, reenter the gray substance and serve to coordinate different
levels of the cord.
The tract-cells may be further divided into two categories : homo-lateral and
contra-lateral tract-cells. Homo-lateral cells are those whose axones enter the white
856 THE NERVE SYSTEM
columns of the same side ; contra-lateral cells are those whose axones traverse the
white ventral commissure to the other side. Tract-cells exist in all parts of the
gray substance and are termed, according to their situation: ventral-, lateral-, and
dorsal-horn cells. The contra-lateral tract-cells preponderate in the dorsal horn,
its cervix, and in the intermediate zone, and, on account of their course, are also
called commissural cells.
(c) Nerve-cells of Golgi's type II, or cells with short, multi-branched axones.
The motor ventral-horn cells differ, therefore, from the other categories in that
they alone send their axones out of the central axis to the periphery. The tract-
cells, commissural cells, and the Golgi type II cells are strictly confined to the
central axis; the tract-cells serve to coordinate the separate units of the spinal
neurone system with higher centres; the association-cells maintain the paths of
conduction between higher and lower cell-complexes; while the cells of Golgi's
type II are limited to a narrower field of nerve-activity as nerve links in the
chaining together of neurones.
White Substance. — The white substance consists essentially of axones the great
majority of which are disposed longitudinally. These axones comprise:
(a) Axones arising in the cerebral cortex, the gray ganglionic masses in the
mid-brain, pons, and cerebellum, and descending to their terminations in different
levels of the cord.
(6) Axones which, conversely, arise in the gray substance of the cord (tract-cell
axones), to terminate in the higher brain-centres.
(c) Axones which coordinate different levels of the cord with each other (associa-
tion-cell axones.)
(d) Axones which, arising from the spinal-ganglion cells of the dorsal-nerve
roots, enter the cord and ascend in the dorsal columns.
Dissection. — To dissect the cord and its membranes it will be necessary to lay open the
whole length of the vertebral canal. For this purpose the muscles must be separated from the
vertebral grooves, so as to expose the spinous processes and laminae of the vertebrae; and the
latter must be sawed through on each side, close to the roots of the transverse processes, from
the third or fourth cervical vertebra above to the sacrum below. The vertebral arches having
been displaced by means of a chisel and the separate fragments removed, the dura will be
exposed, covered by a plexus of veins and a quantity of loose areolar tissue, often infiltrated
with serous fluid. The arches of the upper vertebrae are best divided by means of a strong
pair of cutting bone-forceps or by a rachitome.
MEMBRANES OF THE CORD.
The membranes which envelop the spinal cord are three in number. The most
external is the dura, a strong fibrous membrane which forms a loose sheath around
the cord. The most internal is the pia, a cellulo-vascular membrane which closely
invests the entire surface of the cord. Between the two is the arachnoid, a non-
vascular membrane which envelops the cord and is connected to the pia by
slender filaments of connective tissue.
The Spinal Dura (Dura Spinalis) (Figs. 528, 530, 547, 549).
The spinal dura represents only the meningeal or supporting layer of the cranial
dura. The endocranial or endosteal layer ceases at the foramen magnum dor-
sally, but reaches as low as the third cervical vertebra ventrad; below these
levels its place is taken by the periosteum. The dura forms a loose sheath which
surrounds the cord and the cauda equina, and is loosely connected with the
vertebral periosteum and the ligaments by a quantity of lax areolar tissue and a
plexus of veins, the meningo-rachidian veins (plexus venosi vertebrales interni). The
MEMBRANES OF THE CORD
857
space containing the fat and veins is called the epidural space (cavum epidurale}.
The situation of the veins between the dura and the periosteum of the vertebrae
corresponds therefore to that of the cranial sinuses between the endocranial and
supporting layers. The dura is attached to the circumference of the foramen
magnum and to the axis and third cervical vertebra ; it is also fixed to the posterior
common ligament, especially near the lower end of the spinal canal, by fibrous
slips; it extends below as far as the second or third piece of the sacrum; here it
becomes impervious, and, ensheathing the filum terminale, constitutes the filum
durae spinalis (Fig. 530), and descends to the dorsum of the coccyx, to blend with
the. periosteum. This part of the dura
is called the coccygeal ligament (Fig.
549). The dura is much larger than is
necessary for its contents, and its size is
greater in the cervical and lumbar re-
gions than in the thoracic. Its inner
surface is smooth. On each side may
VENTRAL
NERVE ROOT
FIG. 547. — The spinal cord and its membranes.
FIG. 548.— The dentate
opened and turned back.
(Hirschfeld.)
ligament. The dura has been
The ventral surface is seen.
be seen the double openings, which transmit the two roots of the corresponding
spinal nerve, the fibrous layer of the dura being continued in the form of a tubu-
lar prolongation on them as they pass through these apertures. These prolonga-
tions of the dura are short in the upper part of the spine, but become gradually
longer below, forming a number of tubes of fibrous membrane, which enclose the
sacral nerves, and are contained in the vertebral canal.
The chief peculiarities of the dura of the cord, as compared with that investing
the brain, are the following:
The dura of the cord is not closely adherent to the bones of the vertebral canal,
and is not, as is the cranial dura, the internal periosteum of the vertebrae. The
vertebrae have an independent periosteum.
It does not send partitions into the fissures of the cord, as the cranial dura
sends partitions into certain fissures of the brain.
Its fibrous laminae do not separate to form venous sinuses, as in the cranium.
It contains no Pacchionian bodies.
858
THE NERVE SYSTEM
Structure. — The dura consists of white fibrous and elastic tissue arranged in
bands or lamellae, which, for the most part, are parallel with one another and
have a longitudinal arrangement. Each surface is covered by a layer of endothelial
cells. It is sparingly supplied with vessels, and some few nerves have been traced
into it.
FILUM
TERMINALE
COCCYGEAt
LIGAMENT
FIG. 549. — The filum terminate (schematic). (Poirier and Charpy.)
The Arachnoid (Arachnoidea Spinalis) (Figs. 528, 547).
The arachnoid is exposed by slitting the dura and reflecting that mem-
brane to either side. It is a thin, delicate, tubular membrane which invests
the surface of the cord, and is connected to the pia by slender filaments of con-
nective tissue. Above, it is continuous writh the cranial arachnoid; on each side
it is continued on the various nerves, so as to form a sheath for them as they
pass outward to the intervertebral foramina. The outer surface of the arachnoid
is in contact with the inner surface of the dura, and the two are, here and there,
joined together by isolated connective-tissue trabeculse. These trabeculse are
especially numerous on the posterior surface of the cord. For the most part,
however, the membranes are not connected together, and the interval between
them is named the subdural space (cavum subdurale). The subdural space con-
tains a very small amount of lymph-like fluid. There is no communication
between the subdural and the subarachnoid spaces. The subdural space is pro-
longed outward for a short distance on each emerging nerve and communicates
with the lymph tract of the nerve. The inner surface of the arachnoid is separated
THE PI A OF THE CORD
859
from the pia by a considerable interval, which is called the subarachnoid space
(cavum subarachnoideale). The space is largest at the lower part of the spinal
canal, and encloses the mass of nerves which forms the cauda equina. Cephalad
ft is continuous with the cranial subarachnoid space, and communicates with the
general ventricular cavity of the brain by means of openings in the pia, in the
roof of the fourth ventricle, the metapore or foramen of Majendie and foramina
of Key and Retzius. It contains an abundant serous secretion, the cerebro-
spinal fluid (liquor cerebrospinalis). This secretion is sufficient in amount to
expand the arachnoid, and thus to distend completely the whole of the space in-
cluded in the dura. The subarachnoid space is occupied by trabeculse of delicate
endothelial covered connective tissue, connecting the pia on the one hand with
the arachnoid on the other. This is named subarachnoid tissue.
In addition to this the space is partially subdivided by a longitudinal mem-
branous partition, the septum posticum or the posterior fenestrated septum (septum
subarachnoideale), which serves to connect the arachnoid with the pia, opposite
the dorso-median fissure of the spinal cord. It is a partition, but an incomplete
and cribriform partition, consists of bundles of white fibrous tissue interlacing
with each other, and is coated with endothelium. The dentate ligament (liga-
menia denticulate), which run from the pia to the dura on either side of the
cord, divide the subarachnoid space into an anterior and a posterior space (cavum
subarachnoideale anterius et posterius), which join like spaces in the cavity of the
cranium. The external spinal veins (venae spinales externae) lie in the subarach-
noid space.
Structure. — The arachnoid is a delicate membrane made up of closely arranged
interlacing bundles of connective tissue in several layers. It contains many elastic
fibres, and is covered on each side by endothelial cells. The arachnoid contains
neither vessels nor nerves.
Dura
Arachnoid
Dorsal root
Ventral root
The Pia of the Cord (Pia Spinalis).
The pia of the cord is exposed on the removal of the arachnoid (Figs. 547
and 548). It covers the entire surface of the cord, to which it is very intimately
adherent, forming its neurilemma, and send-
ing a process downward into its ventral fis-
sure. It also forms a sheath for each of the
filaments of the spinal nerves, and invests the
nerves themselves. A longitudinal fibrous
band extends along the middle line on its
ventral surface, called by Haller the linea
splendens; and a somewhat similar band,
the ligamentum denticulatum, is situated on
each side. At the point where the cord
terminates the pia becomes contracted, and
is continued caudad as a long, slender fila-
ment, the filum terminate (Fig. 549), which
descends within the sheath of the dura and
the arachnoid and through the centre of
the mass of nerves forming the cauda equina.
It unites with the dura and arachnoid about the level of the third sacral vertebra,
and as the central ligament of the spinal cord, the coccygeal ligament, or the filum
durae spinalis the fused membranes extend caudad as far as the base of the coccyx,
where they blend with the periosteum. It assists in maintaining the cord in its
position during the movements of the trunk. It contains a little gray nerve
substance, which may be traced for some distance into its upper part, and is
Dura
Plexus venosvs
Vasa vertebralia
FIG. 550. — Transverse section of the spinal
cord and its membranes. (Gegenbauer.)
860 THE NERVE SYSTEM
accompanied by a small artery and vein. At the upper part of the cord the
pia presents a grayish, mottled tint, which is owing to yellow or brown pigment-
cells scattered among the elastic fibres.
Structure. — The pia of the cord is less vascular in structure, but thicker and
denser, than the pia of the brain, with which it is continuous. It consists of two
layers: an outer, resembling the arachnoid, composed of bundles of connective-
tissue fibres, arranged for the most part longitudinally; and an inner (intima pia),
consisting of stiff circular bundles of the same tissue, which present peculiar
angular bends. It is covered on both surfaces by a layer of endothelium. Be-
tween the two layers are a number of cleft-like lymphatic spaces which com-
municate with the subarachnoid cavity, and a number of blood-vessels which are
enclosed in a perivascular sheath, derived from the inner layer of the pia,
into which the lymphatic spaces open. The pia contains the anterior spinal
artery and its branches, the two posterior spinal arteries, and numerous veins
which pass to the external spinal veins. It is also supplied with nerves, which are
derived in part from the sympathetic and in part from the cerebro-spinal nerves.
These nerves supply the walls of the blood-vessels and enter the cord with the
vessels.
The Dentate Ligament (ligamentum denticuLatum} (Figs. 528 and 548) is a narrow,
fibrous band, situated on each side of the spinal cord, throughout its entire length,
running from the pia to the dura, and separating the ventral from the dorsal
roots of the spinal nerves. It has received its name from the serrated appearance
which it presents. Its inner border is continuous with the pia at the side of the
cord. Its outer border presents a series of triangular, dentated serrations, the
points of which are fixed at intervals to the dura. These serrations are twenty-
one in number on each si4e, the first being attached to the dura opposite the
margin of the foramen magnum between the vertebral artery and the hypoglossal
nerve, and the last near the lower end of the cord. Its use is to support the cord.
Surgical Anatomy. — Evidence of value in the diagnosis of meningitis may be obtained by
the operation of lumbar puncture, that is, by puncturing the theca of the cord and withdrawing
some of the cerebro-spinal fluid, and the operation is regarded by some as curative, under the
supposition that the draining away of the cerebro-spinal fluid relieves the patient by diminish-
ing the intracranial pressure. Lumbar puncture may give important diagnostic aid after a
head injury by disclosing bloody cerebro-spinal fluid. The operation is performed by inserting
a trocar, of the smallest size, below the level of the fourth lumbar vertebra. In an adult the
cord terminates at the lower border of the first lumbar vertebra, and in a child opposite the
body of the third lumbar vertebra. The canal may be punctured below the fourth vertebra
without any risk of injuring its contents. The point of puncture is indicated by laying the
child on its side and dropping a perpendicular line from the highest point of the crest of the
ilium; this will cross the upper border of the spine of the fourth lumbar vertebra. In a child
the puncture is made just below the vertebral spine. In adults one-half an inch to one side of
the end of the vertebral spine. However the preliminary puncture is made, the needle pene-
trates the dura in the middle line. In entering the needle it should be directed upward and
forward in a child; upward, forward, and slightly inward in an adult.
THE BRAIN OR ENCEPHALON,
The brain is that greatly modified and enlarged portion of the cerebro-spinal
axis which, with its membranes, almost completely fills the cavity of the cranium.
It is a complex organ in which reside the highest functions — consciousness, idea-
tion, judgment, volition, and intellect — together with the centres of special sense
and for the mechanism of life (respiration and circulation), and it is the agent of
the will.
1 General Appearance and Topography of the Brain. Corresponding to the
varieties of cranial form, the shape of the fresh or the successfully preserved brain
THE BRAIN OR ENCEPHALON 861
varies from the ovoid to the nearly spherical form, as viewed dorsally. The
frontal pole is usually narrower, though more squarely formed ; while the parieto-
occipital portion is more massive, but more sharply pointed in each half. The
outline is often rather that of an irregular pentagon with its angles rounded off.
A dorsal view shows only the extensive convex surface of the two great convoluted
hemicerebra (cerebral hemispheres] separated by a median cleft, the intercerebral
fissure (jissura longitudinalis cerebri). On divaricating the cerebral halves it is
seen that the separation is not a total one, for in the depths of the fissure a broad
commissural mass of white fibres — the callosum — joins the hemicerebra. Frontad
the intercerebral fissure is continued to the ventral or basal aspect of the brain;
caudad it passes into the tentorial hiatus (jissura transversa cerebri} or interval,
separating the cerebrum from the cerebellum.
In a lateral view the continuity of the spinal cord with the oblongata, then the
pons and cerebellum are seen in part, overlapped by the cerebrum. Prominent
is the temporal lobe with its rounded pole, separated from the frontal and parietal
lobes by a deep cleft, the sylvian fissure, in whose depths — overlapped by the
opercula of the adjacent lobes — lies the insula.
A ventral view presents many of the subdivisions of the brain. Here is seen
the continuity of the spinal cord, with the short and slightly expanding oblongata
lying ventrad of the cerebellum and somewhat buried in its vallecula or depression
between the lateral hemispheres, which alone are visible. The cerebellum is a
grayish-colored mass of considerable size and easily recognized by its foliated
appearance, due to the numerous parallel and closely-set curved fissures. A mass
of white fibres, the pons, passes transversely from one cerebellar hemisphere to
the other, ventrad of the upper portion of the oblongata. Above the pons are
seen two large bundles, the crura, one on either side, diverging to pass into the
cerebral halves. The interval between the divergent crura and temporal poles
laterad and the orbital portions of the cerebrum frontad contains a number of
important structures. Encircling the crura and meeting in the fore-part of the
fossa are the optic tracts, decussating in the median plane to form the chiasm and
continuing frontad as the optic nerves. The arch of the optic tracts and chiasm
and the crura enclose the intercrural space, in which may be seen (1) the postper-
foratum (substantia perforata posterior); (2) the albicantia (corpora albicantia;
c. mammillaria;c. candicantia) ; (3) the tuber (tuber cinereum), and the stalk of the
hypophysis. A groove marking the lateral boundary of the fossa along each crus
is termed the oculomotor sulcus, as the root-fibres of the oculomotor nerve have
their superficial origin therein. The postperforatum is a gray area with numerous
minute apertures for the entrance of postperforant branches of the post-cerebral
artery. The albicantia are two small, pea-like, white eminences closely set side
by side. The tuber is a conical projection between the albicantia and the chiasm,
to which the hypophysis (pituitary body), resting in the sella of the sphenoid, is
attached. In the removal of the brain from the skull the stalk of the hypophysis
is usually torn through and an orifice, the lura, leading to the infundibular recess
of the third ventricle, is thus exposed.
In the interval between the optic tract and the orbital surface of each hemi-
cerebrum a small, depressed, triangular area of gray substance leading laterad into
the basisylvian fissure and dotted with numerous apertures for the minute basal
branches of the medicerebral artery and called the preperforatum.
If the chiasm be drawn somewhat ventrad, a delicate gray lamina, the terma
(lamina terminalis; lamina cinerea) is seen attached to the dorsal surface of the
chiasm and passing dorsad into the intercerebral cleft to the region of the precom-
missure.
Parallel to the mesal border of the orbital surface of each hemicerebrum lie
the olfactory tract and bulb, torn away from the fila olfactoria as these pass through
862
THE NERVE SYSTEM
the cribrosa of the ethmoid. The olfactory tract may be traced to its root-area,
the olfactory trigone, just frontad of the preperforatum.
The superficial origin of nearly all of the cranial nerves may be seen upon the
basal aspect of the brain (Fig. 551). These nerves, their superficial attachments
to the brain, and the foramina of exit in the skull are enumerated in the following
table :
TABULATION OF THE CRANIAL NERVES, THEIR SUPERFICIAL ATTACHMENTS TO
THE BRAIN, AND THE FORAMINA OF EXIT IN THE SKULL.
NERVE.
SUPERFICIAL "ORIGIN" OR AT-
TACHMENT TO THE BRAIN.
FORAMEN OF EXIT FROM THE
SKULL.
I. Olfactory fila.
II. Optic nerve.
III. Oculomotor nerve
IV. Trochlear nerve. .
V. Trigeminal nerve.
VI. Abducent nerve.
VII. Facial nerve.
VIII. Acoustic nerve.
IX. Glosso-pharyngeal
nerve.
X. Vagus nerve.
XI. Accessory nerve.
XII. Hypoglossal nerve,
Olfactory bulb and tract.
Chiasm.
Oculomotor groove along medial
border of crus.
Valvula, laterad of frenulum.
Prelateral part of pons.
Postpontile groove (prepyram-
idal part).
Postpontile groove (laterad of
abducent nerve in preolivary
part) .
Postpontile groove (laterad of
facial nerve).
Dorso-lateral groove of oblongata.
Dorso-lateral groove of oblongata.
(a) Encephalic part : Dorso-lateral
groove of oblongata.
(6) Spinal part: Lateral column
of spinal cord, between ven-
tral and dorsal roots of cer-
vical nerves as far as the fifth
and sixth cervical nerves.
Pyramido-olivary groove.
Ethmoidal cribrosa.
Optic foramen.
Superior orbital fissure.
Superior orbital fissure.
(a) Ophthalmic ramus, superior
orbital fissure.
(b) Maxillary ramus, foramen
rotundum.
(c) Mandibular ramus, foramen
ovale.
Superior orbital fissure.
Porus acusticus internus ; meatus
acusticus internus; facial canal;
stylomastoid foramen.
Porus acusticus internus.
Jugular foramen.
Jugular foramen.
Jugular foramen.
Canalis hypoglossi (" anterior
condyloid foramen").
The olfactory, optic, and acoustic nerves are afferent or sensory nerves.
The trigeminal, glosso-pharyngeal, and vagus nerves are mixed nerves.
The oculomotor, trochlear, abducent, facial, accessory, and hypoglossal nerves are efferent or
motor nerves.
Dimensions. — The sagittal or fronto-occipital diameter of the white male
adult brain averages 16 to 17 cm.; the maximum width in the parietal region
averages 13 to 14 cm., while the maximum height is about 12.5 cm. The dimen-
sions of the female brain are usually somewhat less. The brains of dolichocephalic
THE BRAIN OR ENCEPHALON
863
individuals are naturally longer and narrower than those of brachycephalic, and
other differences in size and shape are found in conformity with the cranial con-
figuration and other factors.
The Development of the Brain and the Usual Classifications of its Sub-
divisions.— The cephalic region of the embryonic neural plate is characterized,
as already pointed out (p. 816), by a rapid process of expansion and intensity of
growth-energy which seems to indicate the higher functional potentiality of what
is to become the brain. The fusion of the margins of the neural plate, proceeding
rapidly cephalad and caudad from about the cervical region, soon effects the
FIG. 551. — Basal aspect of the brain showing the superficial origin of the cranial nerves.
numerals indicate the nerves.
The Roman
complete closing in of the brain portion of the neural tube and its complete separa-
tion from the overlying ectoderm. For a brief period prior to the completion of
the tube-formation there exists a minute opening affording communication be-
twreen the interior of the neural tube and the surrounding amniotic cavity; this
temporary passage is called the neuropore (Fig. 542), and is morphologically
the cephalic end of the tube. Its adult position is probably in the hypophysial
region.
The simple Jgrab bend~pt expands very early in intra-uterine life in a sac-
like mannFproxjmaj ^rTdigmfierfon of three dilatations or pouches — the primary
864
THE NERVE SYSTEM
brain-vesicles — demarcated by two constrictions.1 The vesicles are designated
respectively the
Fore-brain (Prosencephalon)
Mid-brain (Mesencephalon)
Hind-brain (Rhombencephalon or Metencephalon)
ECTODERM
NEUROPORE
FORE-BRAJN
MID-BRAIN
HIND-BRAIN
PROTOVERTEBRAl.
FIG. 553. — Brain-tube of chick
hours) showing partly
closed brain-tube with eleven
folds or neuromeres. (After C.
Hill.)
/ :..f->Mid-brain
Prepeduncle
Oblongata
FIG. 554. — Scheme showing the connections of the several parts of the brain.
This classification has been found acceptable from every comparative standpoint
in brain morphology, but attempts have been made to establish a further seg-
mentation into definite anatomical divisions regarding which opinions and usages
differ widely and have proven to be a hindrance rather than an aid to the homo-
logization of brain-structures in the vertebrate series. The difficulties in formula-
1 The constriction between mid- and hind-brain has been called the isthmus rhombencephali by Prof. His, and
he regards it as coordinate with the other segments recognized by him; the region, however, no more deserves
a definitive segmental value than would the cephalic constriction even if it were dignified by the term
isthmus prosencephali.
THE BRAIN OR ENCEPHALON 865
ting a satisfactory schema of the segmental divisions of the brain will be overcome,
perhaps, only by distinguishing the neuromeres or neural segments conforming to
the general segmental plan of the vertebrate body. The existence of a neuro-
merism that is akin to the metamerism or serial segmentation of the body, or to
the branchiomerism characterizing the arrangement of the branchial arches,
is indicated in several ways, but thus far only the earliest embryonic stages and
the disposition of certain of the cranial nerves afford a clue to the definitive seg-
mentation of the brain. According to the most recent researches, as many as
eleven, sixteen, and even more neuromeres have been established in various verte-
brate brains. The hind-brain alone shows from six to eight such neural segments
(Figs. 552 and 553). The whole matter is yet so obscure that confusion will be
avoided by restricting our description to the three primary divisions and their deriva-
tives without insisting upon the recognition of further definitive segments proposed
by various authors in consequence of preconceived ideas obtained from the com-
plicated adult structure of the brain. At this transitional period the student is,
however, obliged to be familiar with the commonly accepted — yet provisional —
schemes of segmentation and a comparative view is given in the following table :
TABLE SHOWING COMPARISON OF THE SEGMENTAL SCHEMAS ADOPTED BY
The Anatomische Gesellschaft The Association of American
in 1895. Anatomists in 1897.
f I. RHINENCEPHALON.
Paries ventrales. Paries dorsales. Rulbi olfactorii with their tractg>
VI. TELENCEPHALON.
,• i ,11 • f Corpus striatum ; rhinen- -
Parsopticahypothalami. { cepfaalon; pallium. II. PROSENCEPHALON.
Palliums, connected by part of the
aula and part of the precommis-
[ sure.
V. DlENCEPHALON. - III. DlENCEPHALON.
IV. MESENCEPHALON. 1
Pedunculi cerebri. Corpora quadrigemina.
IV. MESENCEPHALON.
III. ISTHMUS RHOMBENCEPHALI. ' Crura and quadrigeminum.
, • f Brar.hia conjunctiva; vel-
Pedunculi cerebn. j um meduiare anterius
II. METENCEPHALON. ) V. EPENCEPHALON.
Pons. Cerebellum. j Cerebellum; pons; pre-oblohgata.
I. MVELENCEPHALON. ] VI. METENCEPHALON.
Medulla oblongata. j Post-oblongata.
Brief Consideration of the Phases of Development of the Brain-tube.—
I. Fore-brain. — The cephalic or fore-brain vesicle widens and expands most
rapidly and attains to a comparatively large size even before the mid- and hind-
brain vesicles become markedly defined. A series of remarkable developmental
changes ensue in the following order : (a) Optic vesicles appear as two diverticula,
each budding from either side of the primary fore-brain vesicle, their distal ends
growing considerably and coming into contact with the overlying epidermis,
while the proximal or attached ends assume a stalk-like shape. The distal
55
866
THE NERVE SYSTEM
sac-like end becomes invaginated and forms the retina of the eye, while the
stalk upon obliteration of its cavity forms the optic nerve. It is necessary to
state here that as development proceeds the optic stalks become relatively shifted
caudad and form more intimate connections with the thalamus and mid-brain.
Head fold of amnion.
i Forebraiit.
- - Optic reside.
Midbrain.—*F\
Hindbrain
Auditory reside.
:z±
Neural ridge. —
I- — '•»— -Heart.
CjiA---Omphalo-mesenteric vein.
Protovertebrse or
mesoblastic somites.
jR-4-9- - -Sinus rhomboidalis.
Remains of primitive—
streak.
FIG. 555. — Chick embryo of thirty-three hours' incubation, viewed from the dorsal aspect.
(From Duval's Atlas d'Embryologie.)
X 30.
(&) A second pair of budding vesicles arises cephalad in the dorsal portion of
the fore-brain vesicle and are destined to develop into the ponderous hemicerebra
with their great ganglia, growing with great rapidity and exceeding in this respect
all other parts of the brain. The growth of these secondary fore-brain vesicles is
principally in the distal parts, and in this manner each forms a great pouch whose
interior communicates with the primary neural cavity through a small opening,
the porta or foramen of Monro. It must be remembered that in these initial
THE BRAIN OR ENCEPHALON
867
stages the vesicles are all extremely thin-walled, but later the walls thicken or
hypertrophy to a marked degree, so that the neural cavity becomes relatively
small.
(c) Meanwhile (in the fourth week) the most cephalic portion of the fore-brain
also becomes differentiated. As the enlarging hemicerebral vesicles crowd upon
the median, slower-growing portion, there is observed, on either side, the develop-
ment of a groove or furrow, the primary arcuate fissure, which demarcates the
Neural canal
Neural crest
Romatopleure
Pleuroperi-
toneal cavity
Splanchnopleure
Omphalo-
meseiiteric vein
FIG. 556. — Transverse section of a portion of a chick embryo of twenty-nine hours incubation.
(From Duval'a Atlas d'Embryologie.)
olfactory region (rliinencephalon} into a cephalic and a caudal portion. The
cephalic portion develops into a blind tubular diverticulum, which grows cephalad
to form the olfactory bulb and tract, its central cavity becoming obliterated (per-
sistent in certain other mammals), while the caudal portion forms the roots of the
olfactory nerve, the preperforatum and the subcallosal gyre.
(d) At the ventral margin of the hemicerebral or secondary fore-brain vesicle
an excessive proliferation of cells results in the production of several ganglionic
masses — the basal ganglia, of which the largest are the lenticula and caudatum
Forebrain
Imagination of Ectoderm
to form the lens rudiment'
Pigmented layer
' >f retina.
--Nervous part
of retina.
— Optic stalk.
FIG. 557. — Trans-section of head of chick embryo of forty-eight hours' incubation. X 55.
(From Dmal's Atlas d'Kmbryologie.)
(e) The median-cephalic terminal wall intervening between the large hemi-
cerebral vesicles persists as a thin and relatively undeveloped lamina, the terma.
(/) The remainder of the fore-brain undergoes great hypertrophy in its lateral
walls to form the thalami, while the ventral portion develops moderately to form
the hypothalamus, tuber, post-hypophysis, and albicantia. The dorsal wall fails to
develop and remains epithelial except at a point immediately adjacent to the
quadrigeminal lamina of the mid-brain; here a diverticulum grows out to form the
epiphysis (a rudimentary structure in man, but undoubtedly of functional use in
ancestral vertebrates).
868
THE NER VE SYSTEM
(g) The cavity of the primary fore-brain vesicle undergoes alterations in form
as the secondary metamorphoses of its walls proceed in the course of development.
OLFACTORY FOLD
FIG. 558. — Profile views of the brain of human embryos at three several stages, reconstructed from sections:
A , brain of an embryo of about fifteen days; B, brain of an embryo about three and a half weeks old;
C, brain of an embryo about seven and a half weeks old. (After His.)
The hollow cerebral buds so rapidly outstrip all other parts of the brain that their
internal cavities, the lateral ventricles, become the most spacious of the ventricular
THE BRAIN OR ENCEPHALON
869
system. The great hypertrophy of the thalarnic ganglia in the lateral walls of the
primary fore-brain determine the sagittally placed, slit-like form of the so-called
third ventricle. The cavities of the optic and olfactory buds become obliterated.
II. Mid-brain. — The second primary vesicle becomes somewhat later differen-
tiated and takes a less prominent part in the adult brain. Its dorsal wall goes
into the formation of four eminences, the quadrigemina, while the lateral and
ventral sections grow considerably to form the crura. The neural cavity within
the mid-brain persists as the narrow aqueduct joining the third and fourth ventricles.
III. Hind-brain. — The third primary brain-vesicle is demarcated from the mid-
brain by a marked constriction to which has been given the term isthmus rhomb-
encephali. The hind-brain is specially characterized by the great expansion of
its thinned-out, membranous dorsal wall caudad, while cephalad the dorsal wall
becomes very much thickened as the proton or fundament of the cerebellum.
The ventral and lateral parts undergo thickening to form the pons and oblongata.
Pontcommissure.
I Epiphysis.
Cms cerebri.
Aqueduct
Quadrigemina.
i Cerebellum.
^ '-IV. Ventricle.
Cerebral hemisphere. Olfactory lobe or
rhmencephalon.
Terma.
Pons. OMmiftata.
Albicans.
Spinal cord.
Optic nerve. \
Chiasm: j j
Hypophysis. <
Tuber.
FIG. 559. — Median section of brain of human foetus during the third month. (After His.)
Flexures of the Brain-tube. — The difference in growth-rate of the differ-
ent parts of the brain-tube and the marked disproportion between the rapid
brain-growth and slower head-growth causes the encephalic neural tube to become
sharply bent upon itself at certain points. The first flexure to occur is involved
in a bending of the entire head and takes place in the -region of the mid-brain ;
this flexure is termed the cephalic flexure. A second bending of the tube occurs
at the junction of the spinal cord and hind-brain; this is termed the cervical flexure
and is so pronounced in the fifth week of intra-uterine life that the brain-tube and
spinal cord form a right angle with each other. A third flexure is produced, in
consequence of the other two, in the region of the future pons, and is therefore called
the pontile flexure. Subsequently the cervical and pontile flexures are obliterated
by a gradual straightening of this portion of the brain axis.
870
THE NERVE SYSTEM
Dorsal and Ventral Laminae or Longitudinal Zones of the Brain. — Quite
like the longitudinal division of the developing spinal cord, there is a differ-
entiation of the brain-tube into dorsal and ventral zones, though much less clearly
shown. The limiting furrow between the two is not demonstrable in the fore-
brain; at least it is disputed, on good grounds, that it exists there. It Is claimed,
even, that three such longitudinal divisions exist on each side (Kupffer) and the
formation of the cranial nerves is not quite comparable to the spinal nerves,
although there is a fair homology with their dorsal-sensor and ventral-motor func-
tional differentiation, despite their frequent admixture in some cranial nerves or the
DORSAL
LAMINA
FASC.
SOUTARIUS
VAGUS
GANGLION
itxn,
B
RHOMBOIDAL
SECONDARY f Ll P
FASC
SOLITARIU8
OMBOIDAL LIP
(FUSED)
FASC. SOLITARIUS
FIG. 560. — Three stages in the development of the oblongata, showing the metamorphosis of the
rhomboidal lip. (Modified after His.)
total absence of the one category in others. Thus the motor elements do not
extend higher than the mid-brain and the dorsal division preponderates in the
more highly organized parts of the brain, becoming predominant in the higher
vertebrate species — particularly in man.
In its simplest expression the brain is a tube like the rest of the central nerve-
axis, but a remarkably modified one. There is the same primitive endymal
lining throughout its interior; there is likewise a central tubular gray mass of
ganglionic tissue which, however, undergoes nuclear differentiation in some
portions, atrophies in others, while in certain localities it is crowded away from
871
the central cavity by the intrusion of white-fibre masses which are chiefly com-
missural. A total atrophy occurs in a part of the dorsal wall of both fore-brain
and hind-brain; partial atrophy is observable in the floor of the third ventricle,
near the chiasm, once perhaps the optic centre in the earliest of the ancestral
vertebrates, but atrophied in higher forms as the visual tract became secondarily
projected in the mid-brain. Great hypertrophy characterizes the growth of the
gangh'onic gray in the floor of the lateral ventricle (cerebral vesicle), resulting
in the formation of nugget-like masses, the caudatum, lenticula, and amygdala.
The central gray of the primary fore-brain also undergoes great hypertrophy, but
in the lateral walls only, to form the large, compact thalami.
BASAL GANGLIA
Of FORE-BRAIN
QUADRIGEMINA
RETICULAR GANGLIONIC
MASS WITH CRANIA
NERVE NUCLEI
CENTRAL GRAY (FLOOR OF
FOURTH VENTRICLE AND
AROUND AQUEDUCT)
CENTRAL GRAY OF
SPINAL CORD
\«B \
FIG. 561. — Schematic representation of the chief ganglionic categories. Accurate topographical relations and
interconnections are shown in other figures.
As in the cord, fibre masses develop ectad of the central tubular gray in some
localities, while in other regions the ganglionic gray remains at the surface and
the white conducting substance is developed on its inner aspect. Thus we have,
secondarily, the formation of superficial gray matter as the cortex (or rind) of the
cerebrum and cerebellum. The isolation of ganglionic gray masses from the
primitive central tubular gray and their differentiation into cell-nests (nidi or
nuclei) is also observable in the reticular ganglionic formation of the oblongata
and pons as well as in the roof of the mid-brain. Certain aggregations of gray
ganglionic tissue are intercalated in the course of fibre strands, receive an ad-
mixture of these, and are regarded as terminal, interrupting, or as condensing
872 THE NERVE SYSTEM
station^ not unlike some very complex relay telegraph system. The olive, den-
tatum, rubnun, the nuclei of the gracile and cuneate funiculi, the basketwork
intercalations of the reticular and lemniscus fields belong to this intrafascicular
type of ganglionic structures.
The plan of structure of the brain differs, therefore, from the comparatively
simple arrangement of the gray and white substance in the spinal cord. In the brain
the gray substance is not centrally situated throughout, and there is a tendency to
nuclear differentiation of great and small ganglionic masses These are connected
with each other and with the centres in the cord by longitudinal strands of fibres
of greater and lesser length, as well as by transverse associating fibres uniting the
bilateral nuclei of the same ganglionic category; with the periphery they gain
connection through the cranial nerves and (via the spinal cord) the spinal nerves.
In tracing the various structures of the brain from the oblongata to the cere-
bral cortex we follow anatomically what nature has done in the evolution of the
highest type of brain from that of the simplest and most ancient vertebrate. In
the oblongata lie the centres which exert a very direct influence over those of the
entire cord. The striate bodies and the thalami form a connecting link between
Medipeduncle
Postpeduncle
.- //-Oblongata
FIG. 562. — Scheme showing the connections of the several parts of the brain.
the higher cerebral cortex and the oblongata and cord below. The extensive
cerebral cortex, an aggregation of psychic centres and therefore the seat of the
will, controls the activities of the fore-brain ganglia (striatum, thalamus) and
the cerebellar cortex, and these in turn preside over the functions of lower centres,
as in the way of motor responses to external impressions; such reactions may be
delayed or immediate according to the exercise of the will-power residing in the
cerebral cortex.
This control by the will is intensified the higher we ascend the animal scale;
the pyramidal tract, which originates in the cerebral cortex and threads its way
to the motor centres of the spinal cord without interruption along the brain-axis,
is better developed in man than in any other animal. In the course of evolution
the lower or more automatic ganglia and tracts remain relatively about the same
in mass as in other mammalia, but the higher, more intellectual ganglia surpass
these in growth so that there is an apparent but not real diminution of the auto-
matic systems observed in the human brain.
It has been seen from the foregoing brief accounts of the development of the
nervous system that the most prominent feature is the redundant growth of the
DESCRIPTIVE ANATOMY OF THE ADULT HUMAN BRAIN 873
cephalic or brain end of the neural tube. Comparative neuro-anatomic re-
searches have thrown much light upon the probable genesis of this remarkable
characteristic. The ancestral vertebrate, built upon the segmental type, was a
swimming animal, and its locomotion took place in the direction of its long axis.
In its progress through the water the cephalic (or anterior) segments were those
which first encountered the foreign objects floating in the same medium. It was
for these segments to determine the quality of the objects encountered — whether
they were inimical or indifferent or beneficial to its individual ends. The sensory
periphery, in consequence of the demands of evolution, underwent specialization
in the development of olfactory and gustatory end-organs for testing the quality
of the food and of the surrounding medium; optical organs for perceiving rays of
light; auditory organs for the appreciation of certain oscillations of the surround-
ings; while others, strictly tactile in nature, underwent elaboration as such in the
development of sensitive antennae or tentacles. Motor contrivances, useful in
the quest for food or in encounters with the enemy, were developed in the way
of powerful jaws and masticatory muscles. In brief, a remarkable specialization
and differentiation of structure attended the development of the head-end and with
it the central organ of control kept pace. In the human species we find certain
of these structural characteristics in a highly developed condition, while others
have dwindled or disappeared in the course of evolution. Thus in the myxinoid
fishes and the lamprey the cerebral hemispheres themselves are mere appendages
of the olfactory lobes; the sense of smell was probably the most important in lower
animals. In the brain of man conditions are reversed and the olfactory system
is seen to have dwindled to an extreme degree as compared with the immense size
of the cerebrum; this in conformity with the relatively slight use made of the smell-
sense in the mental life of man. Other organs of special sense, however, became
augmented and these, together with the nerve-mechanisms controlling the vital
functions (respiration, circulation), required a more and more elaborate central
nervous organ for the harmonious interaction of the several elements. This
central organ or brain developed, in bulk and complexity, hand in hand with the
increase of the intellectual faculties. Man's most manifest distinction from other
animals has resulted from a remarkable evolutionary growth in brain-size and
brain-power; and as the brain is the material organ of mental and moral mani-
festations, we find in mankind the highest degree of superiority and culture —
not only as compared with the nearest related apes, but of the civilized and pro-
gressive races as compared with the primitive and unprogressive races.
DESCRIPTIVE ANATOMY OF THE ADULT HUMAN BRAIN.
Morphologically considered, the brain consists of a common trunk (or brain-axis)
from which the two cerebral hemispheres crop out like swollen terminal buds,
while the cerebellum is an excrescence of the trunk itself. The axially situated
brain-axis or "brain-stem"1 comprises, roughly speaking, the axial parts of all
three primary divisions of the brain-tube: (a) oblongata, (6) pens, (e) mid-brain,
(d) thalamic division of fore-brain. In this brain-stem lie the majority of the gan-
glionic masses enumerated above, together with the nerve-tracts uniting the vari-
ous cell-nests in (presumable) automatic coordination as well as the great nerve-
tracts connecting the spinal gray with the cerebral hemispheres, the thalami,
1 Also " brain-isthmus," a loosely used term. It may here be remarked that most extant accounts of the
anatomy of the brain over-emphasize the distinction of brain-parts from each other. Some authors follow
one or another system based upon the theories of the segmentation of the brain-tube; others divide the brain
into (a) rhombencephalon or hind-brain and (6) cerebrum, comprising mid- and fore-brain. None of the
classifications proposed are, as already pointed out, quite satisfactory. The continuity of the parts can only
be interrupted arbitrarily, and such procedure leads to a too narrow conception of brain-structures single and
apart rather than serial and connected.
874
THE NER VE SYSTEM
cerebellum, and the ganglia of the oblongata (including the cranial-nerve nuclei),
and still other tracts connecting the oblongata with the cerebral hemispheres, the
cerebellum, and the special ganglia of the pons and mid-brain.
Parts Derived from the Hind-brain (Rhombencephalon). External
Morphology.
The Oblongata (Medulla Oblongata; Spinal Bulb; Post-oblongata of Wilder;
Myelencephalon).
The oblongata is the continuation cephalad of the spinal cord, the transition
lying at the level of the foramen magnum and marked by the decussation of the
pyramids. Its cephalic limit is sharply defined ventrad by the rounded margin
of the pons, while its dorsal surface is sunk into the cerebellar vallecula. The
length of the oblongata along its ventral surface is 20 to 25 mm.; its maximum
width at the pontile end is 17 to 18 mm., and half as much at its transition into
SEMILUNAR GANGLION
OF TRIGEMINAL NERVE
FACIAL NERVE
N. INTERMEDIUS
ACOUSTIC NERVE
GLOSSOPHARYNGEAL NERVE
VAGUS NERVE
ACCESSORY NERVE
HYPOGLOSSAL NERVE
I. CERVICAL NERVE
BASILAR GROOVE
POST-PONTILE RECESS
PYRAMID
OLIVE
DECUSSATION
OF PYRAMIDS
VENTRAL FISSURE
FIG. 563. — Ventral view of pons and oblongata showing the attachments of certain cranial nerves on one side.
* The inter-radicular pons tract or corpus ponto-bulbare, described in the text.
the spinal cord; its maximum thickness is about 15 mm. Its expansion as it
approaches the pons gives it the form of a truncated cone. The ventral surface
rests upon the basilar groove of the occipital.
Fissures. — The ventral and dorsal fissures of the cord are continued upon
the oblongata, making it a bilaterally symmetrical structure. The ventral or
ventro-median fissure (fissura mediana anterior) , at the level of the foramen mag-
num is interrupted by a number of obliquely intercrossing fibres, called the
decussation of the pyramids. Beyond this interruption the ventral fissure passes
cephalad to end at the ventro-caudal border of the pons in a recess called the
postpontile recess or foramen caecum.
THE OBLONG AT A 875
The dorsal or dorso-median fissure (jissura mediana posterior) is of short extent
upon the oblongata, for the neural cavity is here expanded into a rhomboidal
fossa whose dorsal wall, profoundly atrophied, is represented only by a delicate
membranous lamina; the dorsal fissure rapidly becomes shallower as it ascends
to cease at the caudal apex of the " fourth ventricle."
Like the spinal cord, the surface of each half of the oblongata is divided into
three longitudinal districts by fissures called the ventro-lateral and dorso-lateral
fissures. Of these the latter only is a continuation of the fissure of the same
name in the spinal cord.
The ventro-lateral fissure (sulcus lateralis anterior] of the oblongata demarcates
the ventral column (pyramid) from the lateral column as well as the olive, and the
roots of the hypoglossal nerve, arranged in linear order, emerge from this fissure.
(The ventro-lateral fissure of the spinal cord becomes obscured as it ascends into
the oblongatal region, for cephalad of the emergence of the ventral roots of the first
cervical nerve a band of superficial arcuate fibres usually obliterates all traces of the
furrow.)
The dorso-lateral fissure (sulcus lateralis posterior) of the oblongata is directly
continuous with the same-named fissure of the spinal cord, and the root-bundles
of the accessory, vagus, and glosso-pharyngeal nerves are attached along the bot-
tom of this fissure. Unlike the dorsal roots of the spinal nerves, the root-bundles
of these three cranial nerves are not all composed of afferent fibres arising in
extraneous ganglionic cells and entering the oblongata, for the accessory nerve
is purely efferent and the vagus contains both afferent and efferent fibres.
Areas. — The ventro-lateral and dorso-lateral fissures with their rows of nerve-
fascicles divide the surface of the oblongata on each side into three districts which
appear to be continuous with the three columns of the spinal cord ; they are not so
in reality, however, owing to the rearrangement of the fibre-tracts and the central
ganglionic mass in the myel-oblongatal transition. This portion of the brain-
axis is sculptured into several eminences and depressions; of the eminences, some,
like the olives, the tubercula cinerea, and the clavse are due to the accumulation
of gray substance beneath the surface at that point; others, like the pyramids
and restes, are due to the prominence at certain points of the surface of the great
nerve-tracts.
AREAS OF THE OBLONGATA.
I. Ventral Area:
Pyramid.
II. Lateral Area:
(a) Lateral Tract.
(6) Olive.
III. Dorsal Area, marked by slight furrows dividing it into:
(a) Funiculus gracilis.
(6) Funiculus cuneatus.
(c) Funiculus lateralis and tuberculum cinereum.
The last three structures mentioned appear to become fused cephalad to con-
tinue as the restis; in reality the restis is formed in a different manner.
I. The Pyramids (pyramis medullae oblongatae). — The pyramids constitute the
oblongatal portion of the direct cerebro-spinal efferent tracts conveying (voluntary)
motor impulses from the precentral cortex, through the internal capsule, crusta,
and ventral pons to descend in the crossed and direct pyramidal tracts to the
efferent (motor) cell-groups in the ventral horns of the spinal gray. In their
external appearance in the oblongata they are moderately constricted at their
pontile ends, appear to become somewhat expanded, to again taper as they pass,
partly into the ventral columns of the cord, partly, by decussation, into the lateral
876 THE NERVE SYSTEM
columns. The pyramids are separated from each other by the ventral (or ventro-
median) fissure except where this is more or less completely obliterated by the
decussating bundles. Each pyramid is bounded laterally by a slight furrow, the
ventro-lateral or pyramido-olivary groove, in which arise the hypoglossal nerve-
roots and which separates the pyramid from the olive. The pontile end of each
pyramid is frequently traversed by a band of arched fibres (fibrae arcuatae ectales;
ponticulus of Arnold (not the ponticulus of Henle), the ectal arcuate fibres.
The De cassation of the Pyramids (decussatio pyramidum) is a term given to the
obliquely intercrossing bundles seen at the oblongata-myelon transition. The
extent to which this decussation occurs and the degree of its visibility varies in
different individuals. While in most cases the majority (90 per cent.) of the fibres
cross the median line in this decussation to continue as the crossed or lateral
pyramidal tract, it is sometimes observed that a larger share of the fibres pass
into the direct or uncrossed pyramidal tract with a corresponding reduction of the
crossed tract. Occasionally the decussating bundles are so deeply situated in the
ventral fissure as not to be visible.
II. Lateral Area. — The lateral area of the oblongata is continuous with that of
the spinal cord and is bounded by the dorso-lateral and ventro-lateral fissures.
It is composed of the ventro-lateral spino-cerebellar tract (fasciculus anterolateralis
super ficialis), the ventro-lateral ground-bundle (fasciculus proprius anterolateralis),
and the direct spino-cerebellar tract (fasciculus cerebellospinahs [Flechsig]), while it
is invaded from above by the crossed pyramidal tract. The olive is interpolated
in the cephalic part of this area.
The Olive (oliva; olivary body) is a prominent, elongated oval mass bulging from
the cephalic part of the lateral area of the oblongata, bounded by shallow grooves,
of which one, for the hypoglossal nerve-roots (ventro-lateral fissure) separates it
from the pyramid, while the other, containing the nerve-fascicles of the vagus,
glosso-pharyngeal and accessory nerves, separates the olive from the restis. From
the pons it is separated by a shallow groove in which a band of arched fibres is
sometimes seen. Numerous white fibres (ectal arcuate fibres) emerging from the
ventral fissure and traversing the pyramid loop across the lower parts of the olive
to enter the restis. The olive is formed by the olivary nucleus, embedded in a thin
layer of white matter.
The olive is about 12 mm. in length and 5 mm. in breadth.
III. Dorsal Area, (a) Funiculus Gracilis. — The funiculus gracilis is the direct
continuation of the tract of the same name in the spinal cord. It is a narrow
white band placed along the dorso-median fissure, and separated from the
funiculus cuneatus by the dorso-paramedian furrow (sulcus intermedius posterior).
At the apex of the rhomboidal fossa (fourth ventricle) each funiculus gracilis
diverges from the median plane, presenting at this point a club-like enlargement,
the clava. The prominence of the funiculus gracilis (and clava) is due to the
gray nucleus funiculi gracilis beneath.
(b) Funiculus Cuneatus. — The funiculus cuneatus is the direct continuation of
the tract of the same name in the spinal cord. It enlarges as it ascends, exhibiting
a slight eminence or enlargement, the cuneate tubercle (tuberculum einereum),
which is marked only in the oblongata of young individuals, and is due to the
nucleus funiculi cuneati beneath.
(c) Funiculus Lateralis and Tuberculum Cinereum. — The funiculus lateralis is a
longitudinal prominence which gradually enlarges cephalad into a slight tubercle,
the tuberculum cinereum (hiberculum Rolandi), marking the approach of the
gliosa to the surface so as to form a prominence at a level with the lower border
of the olive.
The Restis (corpus restiforme) occupies the upper dorso-lateral area of the oblon-
gata on each side, lying between the floor of the fourth ventricle and the roots
THE PONS AND PRE-OBLONGATA
877
of the vagus and glosso-pharyngeal nerves. This structure might at first glance
appear to be the continuation of the three funiculi just described. But as a matter
of fact it is made up of the direct spino-cerebellar tract, a set of ectal arcuate fibres
(fibrae arcuatea externae) and a set of ental arcuate fibres (fibrae arcuatae internae).
Each restis assists in forming the lower part of the lateral boundaries of the
fourth ventricle and then enters the cerebellum as the postpeduncle of that body.
The Pons and Pre-oblongata (Pons Varolii; Protuberantia Annularis).
The pons is a prominent white mass on the ventral aspect of the brain-stem
which is interposed between the oblongata and the crura. It is convex from side
to side and its fibres, running chiefly in a transverse arched direction, are gathered
into rounded, compact strands on either side, to continue as the medipeduncles
into the white substance of the corresponding cerebellar hemisphere. The fibre-
bundles of the pyramidal tracts thread their way through the pons on either side
Superficial
and middle
fibres of pons
FIG. 564. — Superficial dissection of the oblongata and pons. (Ellis.)
of the median plane and small aggregations of gray sijbstance (nuclei pontis) are
packed in the intervals between the transverse pontile and longitudinal pyramidal
fibre-bundles.
The Ventral Surface (pars basilaris pontis). — The ventral surface of the
pons is in relation with the basilar process of the occipital and the dorsum
sellfle of the sphenoid. A shallow mesal groove lies between the eminences por-
duced by the pyramidal tracts in their course through the pons. The groove is
called the basilar groove (sulcus basilaris}, as the basilar artery is usually accom-
modated in it; the artery is not, however, a factor in the production of the groove.
The large sensor and small motor-root bundles of the trigeminal nerve pierce the
mass of the poris near the prepontile border, and a line drawn from this nerve-
878
THE NERVE SYSTEM
root to that of the facial nerve is usually employed as an arbitrary boundary
between the pons proper and the medipeduncle of the cerebellum. The abducent
nerve emerges from the postpontile border (prepyramidal part); the facial and
acoustic nerves are attached farther laterad.
While most of the superficial fibre-bundles of the pons are seen to arch trans-
versely, certain small compact bundles1 are seen to extend in an obliquely longitu-
dinal direction from the region of the trigeminal nerve-root to and among the
roots of the facial and acoustic nerves.
The Pre-oblongata (pars dorsalis pontis; pars metencephalica medullae oblon-
gatae). — The pre-oblongata is not sharply demarcated from the oblongata or the
tegmentum and crusta of the mid-brain and
the margins of the pons on the ventral surface
afford only arbitrary boundary lines; for in the
vertebrate series the pons varies greatly in width
and its margins can hardly be accepted as the
boundaries of a definitive brain-segment. The
dorsal surface of the pre-oblongata is continuous
with that of the oblongatal ventricular surface,
and its description more properly belongs to
a consideration of the anatomy- of the fossa
rhomboidalis or "floor of the fourth ventricle."
Fourth Ventricle of the Brain (Ventriculus
Quartus).
In a previous section on brain-development
it has been pointed out how the growth-changes
and differentiations in the hind-brain differ from
those of the rest of the neural tube in that there
is a marked disproportion in the degree of growth
in the dorsal and ventral walls. While the
ventral wall thickens greatly throughout to form
the pons-oblongata, the dorsal wrall hypertrophies
in its cephalic portion to form the cerebellum,
while caudad thereof the roof atrophies and
expands and becomes so attenuated as to be
represented merely by a thin epithelial mem-
brane. The outwrard folding of the walls of the
neural tube in this region creates an expansion
of the central cavity in the form of a rhomboidal
fossa roofed in by the cerebellum and a thin
epithelial layer. A time-honored custom enu-
merates this as the fourth of a system of ven-
tricles of which the other three lie in the fore-
brain.
A cast of the cavity (Fig. 565) shows it to be
irregularly pyramidal, with a lozenge-shaped
base and ridge-like apex extending from side to side, corresponding to the
acute-angled recessus tecti in the fastigium ("gable roof") formed by the
valvula and velum. Such a cast also indicates the ventral extension of the cavity
from the lateral angles of the rhomboidal base in the form of the lateral recesses.
It is customary to describe for the fourth ventricle a roof and a floor, although an
V
FIG. 565. — Plan showing the mode of
formation of the ventricles of the brain
and the central canal of the spinal cord:
A, prosencephalon; B, thalamencephalon;
C, mesencephalon; D, metencephalon; E,
myelencephalon; F, central canal of cord;
G, lateral ventricle; H , porta or foramen
of Monro. (After Gerrish.)
i Called the inter-radicular pons tract by E. C. Spitzka (1884) and more recently described as part of the
corpus ponto-bulbare by Essick (American Journal of Anatomy, vii, 1).
FOURTH VENTRICLE OF THE BRAIN
879
examination of a sagittal section of a brain hardened in situ shows the floor to be
in a vertical plane in the erect attitude. Caudad the cavity is continuous with
the minute central canal of the spinal cord and postoblongata (in part); cephalad
it passes into the aqueduct or mesocele. The dorsal wall or "roof" is formed
by the valvula, the pre peduncles, metatela, and fastigium of the cerebellum. The
ventral wall or "floor" is the rhomboidal fossa occupied by the expanded central
gray of the pre- and postoblongatal portions of the hind-brain.
''Floor" of the Fourth Ventricle (fossa rhomboidea).—The "floor" of the
fourth ventricle is lozenge-shaped and exhibits regional elevations, depressions,
and color differences which are in relation with the deep anatomy of the oblongata
and tegmentum (of pre-oblongata). It is divided longitudinally into symmetrical
halves by a median groove and each lateral half is subdivided into a larger cephalic
and a smaller caudal triangle by white, transverse striae, composed of bundles of
myelinic fibres connected with the acoustic tract and appearing to sink beneath
the surface near the median groove. The portion occupied by these striae acus-
ticae (striae medullares; striae transversales) is termed by His the pars intermedia
as distinguished from the pars superior and pars inferior or frontal and caudal
triangles respectively. Much variation is met with in regard to the course and
FIG. 566. — Varieties of fourth ventricle.
degree of prominence of the striae acusticse (Fig. 566). There may be none visible
or as many as twelve distinct bundles; bilateral symmetry is the exception and
not infrequently one or more bundles run obliquely cephalo-laterad — the striae
obliquae (conductor sonorus). This irregularity of the acoustic striae has led to
another mode of division of the "floor" for descriptive purposes — each side to be
divided into a median and a lateral area, indicated by a more or less well-marked
groove, the lateral furrow (sidcus limitans), connecting the superior and inferior
(a/a cinerea] fovea?. This groove probably corresponds to one of the interzonal
sulci of the embryonic tube and in a gross way it separates the motor and sensor
fields of the "floor." The median area is usually a continuous ridge which is
quite accentuated in the cephalic division as the eminentia abducentis, while caudad
it becomes narrowed as it approaches the closed part of the oblongata. The con-
vergence of the median and lateral furrows at the caudal apex of the rhomboidal
fossa gives the appearance of the point of an ancient writing reed- or quill-pen ;
hence the term calamus scriptorius.
In the caudal quarter-triangle a middle area is occupied by an elongated tri-
angular field whose depressed apex is directed frontad. A slight oblique ridge,
the funiculus separans, composed chiefly of neuroglia, separates the area postrema
880
THE NER VE SYSTEM
caudad from the ala cinerea or trigonum vagi of a pronounced grayish color. The
apical depression has been termed the fovea inferior. Mesally lies a narrow
triangular field with its apex directed caudad and with slightly raised surface
the trigonum hypoglossi. This area is resolved into two fields by a single or double
formation of oblique rugae affording a "feathered" appearance to the lateral field,
area plumiformis. Laterad of the trigonum vagi lies the caudal portion of the
lateral area of the "floor," also called (in part) the area vestibularis (area acustica)
and crossed over its middle by the striae acusticae when these are present. The
area vestibularis is an irregularly triangular raised surface with its convex base
toward the median line, and extending laterally to the attachment of the meta-
tela and into the lateral recess. In the foetus and in certain lower vertebrates
the area is more prominent and is designated the tuberculum acusticum s. vestibu-
laris.
POST-GEMINUM
N.IV
STRIA PONTIS
N. V
LOCUS CCERULEUS-
FOVEA MEOIANA
FOVEA TR
I /
(GEMINI •/- —
EMINENTIA
ABDUCENTIS
AREA VESTIBULARIS
STRI/E ACUSTIOE
N. VIM
N. IX AND X
EMINENTIA HYPOGLOSSI
NUCL. INTERCALATUS —
FOVEA VAGI
LIGULA
AREA POSTREMA
NUCL. CUNEATUS
OBEX
NUCL. GRACILIS
AREA NUCL.
INCERTI
AREA N.
TRIGEMINI
AREA N. FACIALIS
ET ABDUCENTIS
AREA N.
'VESTIBULARIS
AREA NUCL.
FUNIC. TERET.
ARE* N. INTERCALATI
AREA N. VAGI ET
GLOSSOPHARVNGEI
TRACTUS SOLITARIUS
AREA N. HVPOGLOSSI
FIG. 567.— Surface markings and topography of the principal nuclei of the floor of the fourth ventricle.
(Modified from Streeter.)
The "frontal" division of the floor or triangular quarter-field is marked by a
depression at about its middle, the superior fovea, from which the slight "lateral
furrow" runs caudad, and but for the intervention of the striae would reach the
inferior fovea. Cephalad of the superior fovea, and continuing some distance
along the aqueduct, is the locus cceruleus, which owes its color to the refraction
of the pigmented cells, the substantia ferruginea, by the milky-white endyma. At
this altitude, the medial elevation between the superior fovea and the median
sulcus is accentuated into a fairly pronounced eminence, the eminentia abducentis
(eminentia teres}, overlying the nucleus of the abducent nerve and the genu of
the root of the facial nerve. The portion of the median sulcus intervening between
the eminentia abducentia is correspondingly depressed to form the fovea mediana.
The ventricular features enumerated above correspond in a crude way to the
deep structures of the pons-oblongata, and most of the cranial nerve nuclei are
held in a rhomboidal frame formed by the pre- and postpeduncles. The surface-
markings are only imperfect replicas of the subjacent structures : the various cell-
FOURTH VENTRICLE OF THE BRAIN 881
nests overlap each other more or less and their relations can best be studied in
the projection drawing in Fig. 567.
Membranous Portion of the " Roof " of the Fourth Ventricle. — The caudal
extension of the hypertrophied cerebellum hides from view the whole of the rhom-
boidal fossa, but this structure, as before stated, forms but a part of the actual dorsal
wall or "roof." This includes the converging prepeduncles, the valvula intervening
between these, the fastigium of the cerebellum, the velum, and the metatela.
The Velum (velum medidlareposterius}. — The velum is a thin and narrow lamina
of white substance, continued laterad as the flocculi of the cerebellum. At its caudal
edge, i. e., where nerve-tissue ceases, the endyma or ventricular lining epithelium
and the pia over this portion coalesce to form a delicate membrane — the metatela
— attached along the caudo-lateral boundary-line of the rhomboidal fossa. Along
this attachment there is another intrusion of nerve matter between the endymal
and pial layers; this reenforced lamina is usually termed the ligula and may be
traced on the clava and cuneate tubercle, thence laterad over the restis to bound
the lateral recess. The structure is probably a vestige of the secondary rhom-
boidal lip and has actually been found to be a part of the ponto-bulbar body
referred to above. Another small semilunar lamina of nerve tissue bridges the
the caudal apex of the fourth ventricle and is called the obex. This structure is
often devoid of nerve tissue and is then a mere membranous lamina.
Except in rare instances, the metatela is perforated a short distance from the
calamus region. The opening is of variable shape and size; it permits of com-
munication between the ventricular cavity and the subarachnoid space and is
termed the metapore (apertura medialis ventriculi quarti} or foramen of Majendie.
Similar apertures at the extremities of the lateral recesses, and called the
foramina Luschkae (apertura lateralis ventriculi quarti} also permit of a tidal flow
of the cerebro-spinal fluid.
The metaplexuses or choroid plexuses of the fourth ventricle are highly vascular
infoldings of the metatela, one on either side of the, median plane, from each of
which offshoots extend laterad into the lateral recesses. As the choroid plexuses
of the brain are always formed by infoldings or invaginations of the membranous
portions of the brain-tube, the endymal continuity is nowhere interrupted.
Internal Structure of the Postoblongata. — While the spinal cord remains a
closed tube with centrally situated gray, the oblongata opens out on the dorsal
aspect so as to uncover its part of the neural canal as the "floor" of the fourth
ventricle. This involves a tilting of the functionally differentiated gray segments
and, after a gradual transition in the post-oblongata, the motor gray is to be sought
nearest the middle line, the mixed gray just ectad, while the sensor is the outermost
of all. Instead of the ventral, lateral, and dorsal horns of each half of the spinal
cord, we have an ental, middle, and ectal cornu in each half of the oblongata. The
positions alone have changed ; the functional relations to nerve-roots having corre-
sponding functions are homologous. Thus the motor hypoglossal nucleus is
placed in the mesal part of the ventricular floor, while the terminal nuclei of the
afferent vagus, glosso-pharyngeal, and auditory nerves lie in the lateral part.
Another cardinal change in the internal structure of the oblongata, accompany-
ing the preponderating development of the cerebrum and great basal ganglia,
is caused by interrupting and decussating fibre systems which seek passage
through the brain-stem and encroach more or less on its primitive architecture.
While in the spinal cord there is a perfect continuity of the central tubular gray,
we find in the oblongata more pronounced peninsular and isolated insular nuclei
or ganglionic gray masses.
Pyramidal Decussation (decussatio pyramidum). — An important change in the
internal structure is caused by the passage of the fibres of the pyramidal tract as
these pass to the same and opposite sides of the cord, the latter category forming
56
882
THE NER VE SYSTEM
the pyramidal decussation. In consequence of this passage of white (crossed
pyramidal) fibres through its substance the ventral gray horn is broken up into a
coarse network, while one portion of it, the caput cornu, is entirely separated from
the rest; only a small portion of
the base of the cornu remains
intact close to the ventro-lateral
aspect of the central canal. The
caput cornu, thus separated, is
displaced laterally, and comes to
lie close to the caput cornu dor-
salis, which has also shifted its
position. In consequence of this
breaking up of the greater part
of the ventral gray cornu by white
fibres a coarse network is formed
in the anterior and lateral areas
of the medulla, which is named
the formatio reticularis.
The gliosa (gelatinosa Rolandi)
of the dorsal horn is continued
into the oblongata, but becomes
insignificant, relatively, in the
pre-oblongata. The spinal root
of the trigeminal nerve is in ectal
relation with the gliosa; at higher
levels the spinal root of the ves-
tibular nerve intervenes.
Decussation of the Lemnisci. —
A similar change, dorsad and
caphalad of the pyramidal de-
PYRAMIDAL
DECUSSATION
CROSSED PYRAMIDAL
TRACT
DIRECT PYRAMIDAL
TRACT
FIG. 568. — Schema of the pyramidal decussation.
cussation, is caused by the decus-
sation of axone bundles arising in the nuclei of the gracile and cuneate fasciculi
(Goll and Burdach). At this level the base of the dorsal gray cornu undergoes
change in the form of two thick dorsal peninsular outgrowths which form the
DORSO-MEDIAN
FISSURE
DORSO-MEDIAN
DORSO- LATERAL
COLUMN
.CROSSED PYRAM-
IDAL TRACT
VENTRAL.
HORN
VENTRALX
VENTRO-MEDIAN
FISSURE
FIG. 569. — Transverse section of the oblongata at its
lower end. (Testut.)
NUCLEUS GRACILIS
SOR
ROOTS
HEAD OF
DORSAL
HORN
BASE OF
•VENTRAL
HORN
HEAD OF
VENTRAL
HORN
MOTOR
ROOTS
VENTRO-MEDIAN
FISSURE
FIG. 570. — Transverse section of the oblon-
gata at the decussation of the pyramids.
(Testut, after Duval.)
nuclei of termination of theaxones in the gracile and cuneate fasciculi; externally
these gray masses produce the eminences of the clava and cuneate tubercle.
The axones from these nuclei stream mesad and cephalad in a series of con-
FOURTH VENTRICLE OF THE BRAIN
883
centric arches, decussating in the raphe* with the bundles of the opposite side to
form the decussation of the lemnisci1 or sensor decussation. Cephalad of this
decussation the lemnisci are two bundles of fibres coursing on either side of
LATERAL
LEMNISCUS
TRAPEZIUM
MEDIAL
LEMNISCUS
DECUSSATION
OF LEMNISCI'
POSTGEMINUM
NUCLEUS OF
LATERAL LCMNISCUS
VENTRAL
COCHLEAR NUCLEUS
TERMINAL NUCLEI
OF AFFERENT
CRANIAL NERVES
NUCLEUS OF
F. GRACILIS
NUCLEUS OF
F. CUNEATUS
FIG. 571. — Diagram showing the course of the lemnisci and their decussation,
oftEVrUS : DOHSOMEDIAN -
& ^ h^^r— s.ix- — ^^ J%
•HEAD OF DORSAL HORN
BASE OF VENTRAL HORN
HEAD OF VENTRAL HORN
FIG. 572. — Transverse section of the oblongata at the crossing of the fillets. (Testut.)
the raph^ between the olives, and just dorsad of the pyramids; their further course
toward the cerebrum will be described farther on.
1 Also called " mesal lemnisci " in contradistinction to the " lateral lemnisci " — of different origin.
884
THE NERVE SYSTEM
With the extension of the central gray to form the floor of the fourth ventricle,
the caput cornu dorsale is displaced ectad so as to almost reach the surface, where
it forms a projection, the funiculus lateralis (Rolandi), which enlarges caphalad
into a distinct prominence, the tuberculum cinereum. At a higher level the
caput is separated from the surface by the spinal root of the trigeminal nerve and
by the ectal arcuate fibres (Fig. 575). The cervix of the cornu becomes broken
FLOOR OF FOURTH VENTRICLE
NUCLEUS GRACIUS
NUCLEUS CUNEATUS
BASE OF VENTRAL HORN
ROOT OF TRIFACIAL CAPPING
HEAD OF DORSAL HORN -
VAGUS NERVE
HEAD OF VENTRAL HORN
HYPOGLOSSAL NERVE
LEMNISCUS VENTRAL PYRAMID
FIG. 573. — Transverse section of the oblongata at the lower end of the olives. The roof of the fourth
ventricle is not represented. (Testut, after Duval.)
up into a reticular formation by the decussating fibres. A portion of the base
is placed ectad of the nucleus funiculi cuneati and is called the accessory cuneate
nucleus, supposed to be a continuation of Clarke's column.
The Formatio Reticularis (Fig. 575). — The formatio reticularis consists of dif-
fusely scattered gray substance in a. meshwork of white fibres. It is far more
abundant in the pre- and postoblongata than in the cord. In trans-sections of the
postoblongata it is seen to be divided by the hypoglossal nerve-root fascicles into a
HYPOGLOSSAL
NUCLEUS
SENSORY NUCLEUS
NUCLEUS CUNEATUS
HEAD OF DORSAL HORN
ROOT OF TRIFACIAL NERVE
MOTOR NUCLEUS OF MIXED
NERVES
ACCESSORY HYPOGLOSSAL
NUCLEUS
OLIVE
jHYPOGLOSSAL NERVE
VENTRAL
LEMNISCUS' VENTROMEOIAN ARCIFORM
FISSURE NUCLEUS
FIG. 574. — Transverse section of the oblongata at the middle of the olives. The roof of the fourth
ventricle is not represented. (Testut, after Duval.)
mesal and a lateral field. In the mesal field the gray substance is scanty and white
fibres — principally longitudinal ones — preponderate; this is called the formatio
reticularis alba in contradistinction to the lateral grayer reticulated field, the formatio
reticularis grisea. Its numerous nerve-cells mostly possess short axones and for
the most part exercise associative functions for the constantly active centres of
respiration (nuclei of the vagus, phrenic, facial, etc.). Certain axones of longer
course are collected into a small compact bundle just ventrad of the ventricular
FOURTH VENTRICLE OF THE BRAIN
885
floor and central canal (and aqueduct in the mid-brain), and known as the medial
longitudinal fasciculus (posterior longitudinal bundle). This tract is in intimate
association with the cranial nerve nuclei. The formatio alba is principally made
up of this tract and the lemniscus (interolivary stratum).
The Raphe (Fig. 575). — The raphd is situated in the middle line of the oblongata
above the decussation of the pyramids. It consists of nerve-fibres intermingled
with nerve-cells. The fibres have different directions, which can only be seen in
suitable microscopic sections, thus: (1) Some run dorso-ventrad ; these are con-
tinuous with the superficial arciform fibres. (2) Some are longitudinal; these
are derived from the arciform fibres, which on entering the raphe* change their
direction and become longitudinal. (3) Some are oblique; these are continuous
with the deep arciform fibres which pass from the raphe.
The nerve-cells of the raph^ are multipolar; some are connected with the dorso-
ventral fibres, others with the superficial arcuate fibres.
FOURTH VENTRICLE. NUCLEUS INTERCALATU8 FASCICULUS SOLITARIUS
/AND ITS NUCLEUS
DESCENDING ROOT VIII
SUBST.
GELATINOSA
SPINAL ROOT OF
TRIGEMINUS
VAGUS NERVE
DORSAL) ACCESSORY
f OLIVE
MESAL '
XT. ARCUATE FIBERS
HYPOGLOSSAL NERVE
HILUM OLIV/C
ARCUATE NUCLEUS
FIG. 575. — Trans-section of the postoblongata at about the middle of the olive.
The Restis. — The restis succeeds the gracile and cuneate nuclei in the dorso-
lateral part of the postoblongata. Its fibres converge from various sources and
ultimately enter the cerebellum as its postpeduncle. For a description of these
fibre systems see the section on the "peduncles of the cerebellum."
The Nucleus of the Olive or Inferior Olivary Nucleus (nucleus olivarius inferior)
is a corrugated lamina of gray substance whose extent nearly corresponds to that
of the external elevation called the olive. It can be compared to a hollow oval
sac or purse, slit on its mesal aspect and the edges of the slit everted. The opening
is called the hilum. Numerous fibres stream into the interior through the hilum,
while others cut through the lamina to join the fibre-arches of the reticular field and
there passing toward the restis.
What are known as accessory olivary nuclei (nucleii olivarii accessorii) are smaller
detached or semidetached portions of the olivary nucleus named, according to
their position, the dorsal and medial accessory olivary nuclei (nucleus olivarius
accessorius dorsalis et medialis). The root fascicles of the hypoglossal nerve pass
between the medial accessory nucleus and the chief olivary nucleus.
886 THE NER VE SYSTEM
The olivary nuclei play an important part as relay stations in cerebellar connec-
tions. A considerable mass of fibres, the olivo-cerebellar fibres (fibrae cerebello-
olivares), originate in the olivary nucleus of one side to enter the cerebellum
along the restis of the opposite side. A much lesser number of fibres, running
contrariwise, reach the olivary nuclei from the opposite cerebellar hemispheres —
the cerebello-olivary (vestibulo-olivary tract) fibres. The olivary nuclei are also
the termini of two important tracts: (1) the spino-olivary tract or Helweg's bundle
and (2) the thalamo-olivary tract.
The Arcuate Fibre Systems. — The arcuate fibre systems comprise two sets of
fibres according as they course dorsad or ventrad of the olivary nuclei:
1. The Ental Arcuate Fibres comprise the olivo-cerebellar fibres, just described,
and a number of commissural systems for the association of the tegmental retic-
ular gray ganglia and cranial-nerve nuclei. Others pass cerebralward, others
to the cerebellum.
2. The FiCtal Arcuate Fibres take origin (a) from the gracile and cuneate nuclei
and enter the restis of the same side; (6) from the same nuclei of the opposite side,
decussating in the raphe and sweeping ventrad over the pyramid and olive, form-
ing a thin layer over them and ultimately reaching the restis. Many of these
fibres are interrupted, on each side, in the nucleus arcuatus, a thin, isolated
lamina of gray matter lying on the ventral aspect of the pyramid.
The nucleus lateralis is seen in the lateral column (lower part of oblongata) as
a diffuse gray mass lying between the gliosa and the olive; it gradually disappears
cephalad.
The nucleus intercalatus (of Staderini and Van Gehuchteri) forms the elongated,
wedge-shaped elevation in the medial triangle of the caudal portion of the ventric-
ular floor called the area plumiformis (p. 880) ; the nucleus derives its name from
its (intercalated) position between the hypoglossal and dorso-vagal nuclei. Its
functional connections are not yet precisely known.
A nucleus postremus has been described (J. T. Wilson) as lying subjacent to
the area postrema.
The nucleus funiculi teretis lies close to the median sulcus in the altitude of the
acoustic striae, and seems to bear an intimate relation to these.
Summary of the Gray Masses in the Postoblongata:
* Central tubular gray (in "closed" part).
* Gray floor of fourth ventricle (in "open" part).
* Gliosa (or gelatinosa Rolandi).
* Nucleus funiculi gracilis.
* Nucleus funiculi cuneatus.
* Nucleus funiculi cuneati accessorius.
* Nucleus lateralis.
* Nucleus olivaris inferior.
* Nucleus olivaris accessorius dorsalis.
* Nucleus olivaris accessorius medialis.
* Nucleus arcuatus.
Nucleus nervi hypoglossi.
* Nucleus intercalatus.
* Nucleus postremus.
Nucleus vagi (alse cinerese).
Nucleus vestibularis (spinal division).
* Nucleus funiculi teretis.
Nucleus ambiguus.
Nucleus tractus solitarii.
Nucleus tractus spinalis n. trigemini.
* Formatio reticularis.
INTERNAL STRUCTURE OF THE PONS AND PRE-OBLONGATA 887
In the foregoing enumeration of the gray masses of the postoblongata, those
marked with an asterisk have been described above; the remaining structures
relate to the deep connections of the cranial nerves and will be discussed in detail
under that head.
Internal Structure of the Pons and Pre-oblongata. — Trans-sections of the
pons also pass through the pre-oblongata (or tegmental part of the pons). To
consider first the internal structure of the pons proper (or pars basilaris pontis) :
The pons is composed chiefly of (1) transverse fibres arranged in coarse bundles,
(2) longitudinal fibres gathered in compact bundles, and (3) diffusely scattered
masses of gray substance among the fibre bundles, the nuclei pontis.
The Transverse Fibres. — The transverse fibres, corresponding to the large size
of the cerebellum, are more abundant in man, relatively, than in any other animal.
They form a massive series of bundles coursing ventrad of the brain axis from one
cerebellar hemisphere to the other. At the caudal border of the pons they embrace
the pyramidal tracts as well, but farther cephalad the transverse pontile fibres
are seen to intersect the pyramidal tracts, breaking these up into pyramidal
fasciculi; still farther cephalad the pyramidal tracts are wholly embedded in
the mass of transverse pontile fibres so that these in turn, with reference to
the location of the pyramidal tracts, may be divided into a superficial and a deep
set. Laterad they are gathered together to form the medipeduncles (described
on p. 901).
The Longitudinal Fibres. — The longitudinal fibres consist chiefly of the pyramidal
tracts, which are solid strands at their entrance to and exit from the pons, but are
broken up into lesser bundles at its middle. A certain number of the pyramidal
fibres, as well as other cerebro-pontile fibre-tracts, terminate in relation with the
cells of the nuclei pontis, as well as certain of the efferent cranial-nerve nuclei.
This fact accounts for the demonstrable diminution in bulk of the pyramidal
tract in its course through the pons.
The Nuclei Pontis. — The nuclei pontis are small aggregations of gray substance
(which in serial sections show them to be continuations of the arcuate nuclei)
diffusely scattered among the fibre-systems of the pons proper. They are
intercalated in the course (1) of tracts passing from one cerebellar hemisphere
to the other and (2) of descending cerebro-pontile tracts. The cells of the pontile
nuclei send their axones chiefly to the opposite cerebellar hemisphere and plav
an important part as links in the complex chain of the neurone systems which
make the cerebellum such an important organ of senso-motor coordination.
In the contact-zone of pons proper and the pre-oblongata (or pontile tegmentum)
lies a group of transversely decussating fibres with interspersed gray masses with
large cells called the trapezium. This body will be more fully described in con-
nection with the central auditory paths.
The Pre-oblongata. — The pre-oblongata (or tegmental part of the pons) is of much
smaller bulk than the pons proper, as seen on trans-sections. On the dorsal sur-
face is spread a layer of gray substance, covered by endyma, which forms the floor
of the cephalic part of the fourth ventricle. Beneath this gray substance lies the
formatio reticularis divided into symmetrical halves by the raphe" — continued from
the postoblongata. Embedded in the formatio reticularis are various isolated
masses of gray substance and various more or less compact fibre-tracts. Among
the gray masses are several of the cranial-nerve nuclei, to be described in a separate
section, and the following:
The Superior Olivary Nucleus (nucleus olivarius superior] is a small gray mass
or aggregation of several smaller masses situated laterad of the trapezium, inter-
calated in the path of the trapezial fibres and forming a link in the central acoustic
chain (Fig. 579).
888 THE NERVE SYSTEM
The Nucleus Incertus (Streeter) is an aggregation of gray substance in the floor of
the fourth ventricle near the median sulcus and forming a slight, rounded elevation
which extends to the aqueduct. Its functional relations are unknown.
Fibre-tracts in the Pre-oblongata. — Among the fibre-tracts in the pre-oblon-
gata the chief ones are (1) the medial lemnisci, (2) the lateral lemnisci, (3) the
medial longitudinal bundle, and (4) the prepeduncles of the cerebellum.
The Medial Lemniscus. — Each medial lemniscus, in its passage through the
pre-oblongata, is gathered into a compact, ribbon-like bundle along the contact-
zone of the tegmentum and pons proper, latero-ventrad of the trapezium, some
fibres of which traverse it on their way toward the raphe". The medial lemniscus
has been described in the postoblongata as occupying the field between raphe and
inferior olivary nucleus (the interolivary stratum) ; in its ascent the medial lemniscus
gradually trends laterad so that it almost reaches the surface (Figs. 571 and 573).
The Lateral Lemniscus. — The lateral lemniscus is a constituent of the central
auditory path and will be described more fully in the sequel. In trans-sections
above the level of the trigeminal nuclei the lateral lemniscus is seen as a flattened
band spreading over the surface (externally the trigonum lemnisci) ectad of the
prepeduncle. Its fibres are interrupted by an intercalated nucleus of the lateral
lemniscus.
The Medial Longitudinal Bundle (posterior longitudinal bundle). — The medial
longitudinal bundle maintains its position just ventrad of the central gray, close
to the raphe.
The Cerebellar Prepeduncle. — The cerebellar prepeduncle, in trans-sections, is
seen to be a very compact bundle of crescentic outline with the concavity turned
toward the ventricular cavity. Its dorsi-mesal edge is joined to the valvula;
its ventral border is sunk into the tegmentum and in its ascent it becomes sub-
merged laterally beneath the lateral lemniscus, dorsally beneath the quadrigeminal
plate of the mid-brain.
Summary of the Gray Masses in the Pre-oblongata:
Nucleus of Abducent Nerve.
Nucleus of Facial Nerve.
Afferent and Efferent Nucleus of Trigeminal Nerve.
Nucleus of Spinal Root of Trigeminal Nerve.
f Dorsal Nucleus.
fCochlear Division { Ventral Nucieus.
Nuclei of Acoustic Nerve "j ( Medial Nucleus.
^Vestibular Division^ Lateral Nucleus.
( Superior Nucleus.
* Superior Olivary Nucleus.
Nucleus of Trapezium.
* Reticular Ganglionic Formation.
* Nucleus Incertus.
* Nucleus of Lateral Lemniscus.
Those marked with an asterisk have already been described; the remaining
structures relate to the deep connections of several cranial nerves to be described
in the succeeding section.
Central Connections of the Cranial Nerves attached to the Hind-brain.—
Eight of the twelve pairs of cranial nerves are attached to the hind-brain portion
of the central axis. Their superficial or apparent origin and the cranial fora-
mina of exit are enumerated in the table on page 889. In coordination with
the internal descriptive anatomy of the hind-brain the central connections of
these eight cranial nerves must now be considered. They comprise :
CENTRAL CONNECTIONS OF THE CRANIAL NERVES
Purely efferent or motor
nerves.
Mixed nerves.
Purely afferent or sensor
nerve.
[ XII. Hypoglossal nerve.
XI. Accessory nerve.
VII. Facial nerve (proper).
VI. Abducent nerve.
X. Vagus nerve.
IX. Glosso-pharyngeal nerve.
V. Trigeminal nerve.
VIII. Acoustic nerve.
Motor to muscles of tongue.
(a) Motor accessory to vagus
nerve;
(b) Motor to trapezius and sterno-
mastoid muscles.
Motor to muscles of scalp and
face.
Motor to external rectus muscle
of eyeball.
Senso-motor to respiratory tract
and upper part of alimentary
tract.
Sensor to tongue (and motor ?)
to Stylo-pharyngeus muscle.
Sensor to face, tongue, teeth;
motor to muscles of mastica-
tion.
(a) Cochlear division for hearing
(6) Vestibular division for equi-
librium
Another nerve which pursues a remarkably aberrant course, becoming asso-
ciated with three of the above-mentioned cranial nerves, is the nervus intermedius,
known peripherally as the chorda tympani. It is chiefly sensor (taste) in function,
but also contains efferent fibres which are excito-glandular for the submaxillary
and sublingual salivary glands.
In the hind-brain axis lie certain gray masses which are functionally homol-
ogous with the nuclear masses in the different parts of the spinal central gray.
These defined nests of nerve-elements, from their relations to the cranial-nerve
roots, are called the cranial-nerve nuclei or nidi. Their analogy to the origins of
the spinal nerves extends to the shape and character of their cell-elements and
their differentiation into (a) nuclei of origin and (6) nuclei of termination or recipient
nuclei.
The Nuclei of Origin. — Nuclei of origin or motor nuclei are cell-clusters from
which arise the axones of efferent nerves or the efferent components of the mixed
nerves. Some of these nuclei are in line with the basal portion of the ventral
gray horn in the cord below and are termed, owing to their situation near the mesal
plane, the medial nuclei of origin. Other nuclei are isolated cell-columns in the
line of the caput cornu ventrale detached by the decussation of the pyramids,
termed, from their position in the tegmental substance, the lateral nuclei of origin.
The different nuclei of origin of the efferent cranial nerves are under the domi-
nance of the cerebral cortex by way of the cortico-tegmental (or cortico-bulbar)
path — usually included in the pyramidal tract.
The Nuclei of Termination. — The nuclei of termination or sensor cranial-nerve
nidi are likewise repetitions in structure of the dorsal horn of the spinal gray, but
with less regularity and definiteness of position. Thus, while the caput gliosum
of the cord is continuous with the nucleus of the spinal root of the trigeminal
nerve, other recipient or afferent nuclei are more or less isolated in the tegmental
substance, while the two (lateral and ventral) nuclei of the cochlear nerve actually
lie on the surface of the brain-stem.
The afferent impulses carried in by the sensor cranial nerves excite impulses
in the neurones of the nuclei of termination; their axones enter the tegmental
substance as arcuate fibres, cross the mesal plane to join the lemnisci to connect
with the thalamus and postgeminum and via thalamus and postgeminum with
the cerebral cortex.
The location of the various cranial nerve nuclei in the brain-stem may be under-
stood by a reference to the diagrams in Figs. 567, 576, 577, and 578.
Hypoglossal Nerve. — The nucleus of origin of the hypoglossal nerve is a rod-
like cell-column close to the mesal plane, extending for about 7 mm. in the caudal
890
THE NERVE SYSTEM
portion of the fourth ventricle, while its extraventricular portion extends about
5 mm. caudad of the tip of the calamus. Its efferent axones course ventrad
between the formatio reticularis alba and grisea, thence between the olivary and
medial accessory olivary nuclei, to emerge between pyramid and olive. None
of the fibres decussate across the middle line, but the nuclei are coordinated by
commissural fibres. Axones from
cortical cells (ventral third of pre-
central gyre) terminate in relation
with the cells of the hypoglossal
nucleus.
The hypoglossal nucleus permits
of subdivision into groups: (a) a
medial and (6) a lateral sub-group.
The lateral group innervates the
palatoglossus and pharyngoglossus,
while the medial nuclear group in-
nervates the remainder of the tongue
muscles (lingualis transversus and in-
ferior, genioglossus and hyoglossus) .
The Accessory Nerve. — The acces-
sory nerve is also a purely motor
or efferent nerve whose axones arise
from an attenuated nucleus, with
large multipolar cells, in direct con-
tinuation with the nucleus ambiguus
cephalad, and with the dorso-lateral
cell-column of the ventral horn of
the upper five or six segments of the
cord. The oblongatal portion of the
nucleus, giving rise to the enceph-
alic root of the accessory nerve, may
also be termed the nidus laryngei, for
its axones join the vagus Jierve to
innervate the laryngeal muscles (in
contradistinction to the nidus pharyn-
gei or nucleus ambiguus, whose axones
join the vagus and glosso-pharyngeal
to be distributed to the pharynx).
The axones from the spinal nucleus
are distributed to the Trapezius and
Stern o-mastoid muscles.
The nucleus of the accessory nerve
is likewise under the dominion of the
cerebral cortex by way of the pyra-
midal tract, and a reflex arc is completed by afferent axones from the dorsal
roots of the spinal nerves.
The Vagus and Glosso-pharyngeal Nuclei are usually considered in their aggregate,
justified not only by their similarity in origin and central connections, but also
by the uncertainty which prevails regarding their peripheral interlacement and
complex terminations. Both nerves are in greater part afferent, but also contain
efferent axones.
1. Afferent Portions. — The afferent axones of the vagus arise from the cells in the
jugular ganglion and ganglion nodosum (ganglion of the trunk) ; the afferent axones
of the glosso-pharyngeal arise from the cells in its ganglion superius and ganglion
NUCLEUS AMBIGUUS
FIG. 576. — The cranial nerve nuclei schematically rep-
resented in a supposedly transparent brain-stem, dorsal
view. Motor nuclei in red; primary terminal nuclei of
afferent (sensor) nerves in blue. (Optic and olfactory
centres are omitted.)
CENTRAL CONNECTIONS OF THE CRANIAL NERVES
891
petrosum. The root-fascicles of both nerves enter the oblongata along its dorso-
lateral groove and the axones then undergo bifurcation into ascending and de-
scending rami, similar to those of the dorsal roots of the spinal nerves. The
ascending rami end in the nucleus alae cinerese (nucleus vagi et glossopharyngei] ;
the descending rami collect to form a compact bundle called the tractus solitarius
or trineural fasciculus,1 and terminating in a gray cell-column called the nucleus
of the solitary tract2 — a caudal prolongation of the nucleus alse cinerese. Both tract
and nucleus become attenuated caudad, to disappear in the fourth cervical seg-
ment (relation with phrenic nerve nucleus), while cephalad it has been traced as
far as the region of the locus cceruleus (relation with trigeminal nerve nuclei?).
CERVICAL NERVES
FIG. 577. — Nuclei of origin of the cranial motor' nerves schematically represented in a supposedly
transparent brain-stem, lateral view.
From the cells of the nucleus alse cinerese and nucleus tractus solitarii axones
pass across the raph^ to the contralateral interolivary stratum to join the medial
lemniscus, establishing connections with the thalamus and cortex; other axones
join the tractus nucleo-cerebellaris.
2. Efferent Portions. — The efferent components of the vagus and glosso-pharyn-
geal nerves come from two sources: (a) the dorsal efferent (vagal) nucleus and
(6) the nucleus ambiguus.
The dorsal efferent nucleus lies ventro-mesad of the principal nucleus alse cinerese
and laterad of the hypoglossal nucleus. The axones from its cells pass obliquely
ventro-laterad to enter the root-fascicles of the vagus and to become distributed to
'There are other "solitary" fasciculi in the nervous system, and the name "trineural fasciculus" aptly
characterizes a tract which has for its object that mutual interchange of functions among the central nuclei
of the accessory, vagus, and glosso-pharyngeal nerves.
2 The nucleus of the solitary tract lies to the mesal side of the tract. Another nucleus has been described
by Mellus, lying laterad of the tract.
892
THE NERVE SYSTEM
the oesophagus, stomach, trachea, and bronchi. Whether the glosso-pharyngea)
nerve receives efferent axones or not is still in debate.
The nucleus ambiguus (nidus pharyngei) is a rod-like mass of large, multipolai
cells seen, in trans-sections, lying in the gray, reticular formation midway between
olive and trineural fasciculus. The axones arising from its qells run dorsi-
mesad at first, then turn abruptly ectad to join the vagus (and glosso-pharyngeal ?)
nerve-root fascicles, becoming distributed to the pharyngeal muscles, oesophagus,
crico-thyroid and laryngeal muscles.
The Acoustic Nerve. — The acoustic nerve consists of a cochlear and a vestibular
division; the former is concerned with the sense of hearing, the latter with the
sense of equilibrium.
FIG. 578. — Primary terminal nuclei of the afferent (sensor) cranial nerves schematically represented in a
supposedly transparent brain-stem, lateral view. The optic and olfactory centres are omitted.
1. The Cochlear or true auditory nerve arises in the bipolar cells of the cochlear
spiral ganglion; its axones terminate in (a) the dorsal nucleus (tuberculum acusticum),
a pyriform mass on the dorso-lateral aspect of the restis, and (b) the ventral nucleus,
somewhat detached from the former.
From the dorsal nucleus cells arise the axones which compose the striae acusticae,
myelinic fibre-bundles traversing the ventricular surface to near the median
sulcus, dipping into the tegmental substance, crossing to the opposite side in the
raphe, and eventually joining the lateral lemniscus to end in the postgeminum
and postgeniculum.
From the ventral nucleus cells arise the axones which course transversely to form
the trapezium at the contact-zone of the pons proper and tegmentum. Additional
axones from cells in the superior olives of both sides and in the trapezium itself
increase the bulk of this tract; some of the primary axones end in relation with
CENTRAL CONNECTIONS OF THE CRANIAL NERVES
893
these cells. These axone-groups form the contralateral lemniscus lateralis, which
contains the intercalated nucleus of the lateral lemniscus as a relay station, to be
continued to the postgeminum and postgeniculum and thence to the cortical
auditory "centre" in the supertemporal gyre.
2. The Vestibular Nerve axones arise in the bipolar vestibular ganglion cells
(G. of Scarpa), enter the brain-stem, and bifurcate into ascending and descending
rami, which terminate as follows: The ascending rami end in the medial nucleus
(Schwalbe's) ; the descending rami end in the spinal vestibular nucleus, which extends
down to the gracile and cuneate nuclear level; another group of axones ends in
the lateral nucleus (nucleus magnocellularis) (Deiters5); while a fourth and last
group ends in the superior nucleus (Bechterew's). From the cells of all these nuclei
of termination axones proceed toward the cortex, dentatum, and fastigatum of the
cerebellum, as part of the nucleo-cerebellar tract, to the nuclei of the abducent,
trochlear, trigeminal, and oculomotor nerves by collaterals from axones in the
PREGCMINUM
LATERAL
LEMNISCUS
CORTEX
CORTICAL TRACT
POST-GEMINUM
COCHLEAR,
NERVE
DORSA
NUCLEUS
S
LATERAL
LEMNISCUS
RAPHE
FIG. 579. — Diagram of the central auditory tract (system of the second order).
medial longitudinal bundle, to the thalamus, and to the ventral-horn nuclei of
the spinal cord along the tractus vestibulospinalis. The far-reaching and
complex connections of the vestibular nerve with the cerebellum and the
centres for eye-muscles and the spinal centres for bodily movements make this
cranial nerve a most interesting subject for the active research now going on.
The Facial Nerve. — The facial nerve proper is to be distinguished from its
socalled sensor root, or pars intermedia, or nervus intermedius.
The axones of the efferent facial nerve arise from cells forming the facial nucleus
in the ventro-lateral region of the reticular formation, in line with the nucleus
ambiguus or nidus pharyngei, a little over 4 mm. from the ventricular floor. These
axones converge toward the ventricular floor to form a compact bundle which
curves over the abducens nucleus from behind (caudad), overlying it like a horse-
shoe over a ball (genu facialis internum); not as a straight but as a bent horseshoe,
bent so that its cephalic branch is directed more laterad than its caudal branch.
894 THE NERVE SYSTEM
After having encircled the abducens nucleus, the facial root passes ventro-laterad,
passing its own nucleus ectad, and emerging in the postpontile groove (recessus
facialis).
Pyramidal fibres from the precentral cortex place this nucleus under the in-
fluence of the will; it also receives fibres from the trigeminal and acoustic central
systems.
The nervus intermedius is a mixed nerve, containing afferent (taste) fibres and
efferent (excito-glandular or secretory) fibres. With respect to its afferent com-
ponent it may be regarded as an aberrant portion of the glosso-pharyngeal nerve.
1. Afferent Portion. — These axones arise, from the cells of the geniculate ganglion,
implanted upon the genu facialis externum, and terminate in a nuclear extension
cephalad of the nucleus tractus solitaxii. They probably convey gustatory sense
impulses from the tip of the tongue and the pillars of the soft palate.
2. Efferent Portion. — A nucleus of origin for the excito-glandular elements has
been described as a group of cells extending beneath the ventricular floor from
the level of the facial nucleus to that of the motor trigeminal nerve, close to the
raphe", and called the nucleus salivatorius.
Peripherally we shall study this nerve as the chorda tympani. The mixed nature
of the nervus intermedius and of the geniculate ganglion makes it probable that
they combine the elements of a sympathetic and a spinal ganglion; the nerve, at
least, contains both vegetative and sensorial elements.
The Abducent Nerve. — The abducent nerve is a small motor nerve supplying
the External Rectus muscle of the eyeball. Its nucleus of origin, with large, multi-
polar cells, lies close to the median plane beneath the eminentia abducentis. The
axones from these cells pass ventrad through the tegmentum and trapezium, and
laterad of the pyramidal tract, to emerge in the postpontile groove. The nuclei
are brought under the dominion of the cerebral cortex by pyramidal fibres of
the opposite side. They are likewise brought into intimate relation with the
trigeminal, acoustic, and opposite oculomotor nerve nuclei.
The Trigeminal Nerve. — The trigeminal is relatively enormous and has corre-
spondingly extensive central connections, including nuclei in the mid-brain,
pre- and post-oblongata, and spinal cord. It is a mixed senso-motor nerve and
the afferent and efferent divisions must be considered separately.
1. Afferent Portion. — The axones of the afferent or sensor root arise in the cells
of the large semiiunar (Gasserian) ganglion. As in the dorsal roots of the spinal
nerves, these axones bifurcate, on entering the brain-axis, into ascending and
descending rami. These terminate in a cephalic nuclear extension of the caput
gliosum of the cord; the ascending rami terminate in the so-called sensor nucleus
of the trigeminus, the descending rami in the nucleus of the spinal tract of the
trigeminus, which extends as far as the second cervical segment of the cord. The
sensor nucleus, at the level of the entrance of the nerve, is quite massive, becoming
attenuated cephalad. The spinal tract, in its descent, likewise decreases rapidly
as it gives off its terminal axones to the nucleus of the tract. The cells of these
terminal nuclei send out axones which cross the median plane, giving off col-
laterals to the facial nucleus, to join the medial lemniscus to reach the thalamus,
and, via thalamus, the somsesthetic cerebral cortex. Other axones are distributed
(a) to the motor or efferent nucleus of the trigeminus and (6) to the motor or
efferent cranial-nerve nuclei
2. Efferent Portion. — The efferent or motor component of the trigeminal nerve
consists of axones arising from cells in two nidi: (a) the principal nucleus in the
dorso-lateral part of the pre-oblongatal tegmentum, dorso-mesad of the sensor
nucleus; (6) a small, slender, so-called mesencephalic root-nucleus (nucleus radicis
descendentis nervi trigemini) extending cephalad of the region of the locus coeru-
leus to lie along the aqueduct in the mid-brain. The fibres from the principal
THE CEREBELLUM
895
nucleus supply the muscles of mastication. The distribution of the fibres from
the mesencephalic root is not precisely known. Kolliker suggests that they may
supply the Tensor veli palatini, Tensor tympani, Mylo-hyoid and anterior belly of
the Digastric.
Like other motor nuclei, these efferent divisions of the trigeminus are under the
dominion of the cerebral cortex via pyramidal fibres.
The Cerebellum. — The cerebellum occupies the greater part of the posterior
or cerebellar part of the skull and is the largest portion of the hind-brain. It is
overlapped by the occipital lobes of the cerebrum, being separated from these by
the tentorium. It lies dorsad of the pons-oblongata and partly embraces this
portion of the brain-stem. It is composed of a white central core with scattered
gray masses, and a surface layer of gray substance that is of darker hue than the
cerebral cortex.
The cerebellum is convoluted on a plan entirely different from that of the cere-
brum. Each primary fold is folded by secondary and these in turn by tertiary
folds, so that on sagittal section a cypress-leaf appearance is noted, the arbor
vitae cerebelli. The interior or medullary white substance follows all these
branchings and sub-branchings, forming a skeleton of the minute folds which are
called folia. These folia are demarcated on the surface by numerous curved
and more or less parallel fissures of various depths.
Ala lobuli centralis. Post-central Pre-clival fissure.
Lobulus centralis.
Great
horizontal
Jissure.
-clival Jissure.
FIG. 580. — Upper surface of the cerebellum. (Schiifer.)
The cerebellum is connected to the brain-stem by three pairs of peduncles and
by vestigial portions of the primitive dorsal wall of the brain-tube. Among the
latter the medullary vela or laminae are most important; they are the valvula
(superior medullary velum) and the velum (inferior medullary velum), which enter
into the formation of the "roof" of the fourth ventricle.
The rounded margin of the cerebellum demarcates two surfaces looking
respectively "upward" and "downward," or cephalic and caudal surfaces. Both
are convex, the inferior or caudal surface more so than the upper or cephalic.
The inferior surface shows a deep median depression, the vallecula, into which
the oblongata is sunk. The ventral margin is widely notched to partly embrace
the brain-stem (pre-oblongata and quadrigemina) ; a dorsal notch (incisura cerebelli
posterior), which is smaller and narrower and lodges the falcula, separates the
hemispheres as these project beyond the postvermis.
The cerebellum is arbitrarily sub-divided into a medial segment, the vermis or
worm, from its annulated appearance, and two lateral portions, commonly called
896
THE NERVE SYSTEM
the cerebellar "hemispheres" or pileums. The vermis may, according to the aspect
in which it is viewed, be divided into the prevermis on the upper or cephalic sur-
face, and the postvermis on the inferior or caudal aspect. The prevermis is hardly
distinguished from the adjacent sloping surfaces of the hemispheres; occasionally
a slight furrow exists on either side. Ordinarily the term is to be restricted to
the high median elevation usually called the monticulus cerebelli. The postvermis
is more distinctly bounded by a deep fissure, the sulcus valleculse, on each side,
separating it from the corresponding lateral hemisphere.
Among the many fissures which traverse the surface of the cerebellum, one is
particularly conspicuous as a deep cleft which may be traced along -the dorso-
lateral margin from the dorsal notch to the point of entrance of the cerebellar
peduncles. This is the peduncular sulcus or great horizontal sulcus (sulcus horizon-
tails cerebelli), and it divides the cerebellum into a cephalic and caudal or upper
and lower part. The sulcus is usually quite deep in the hemispheral portion, but
it frequently fails to traverse the vermis. Other deep fissures demarcate the lobes
or major sub-divisions of the intricately convoluted surface of the cerebellum.
Post- nodular fissure.
Flocculus.
Pre-
pyramidal
fissur.e.
ho
Great
risontal
fissure.
Post
pyramidal
fissure.
FIG. 581.- — Under surface of the cerebellum. (Schafer.)
Conventionally the lobes and fissures or sulci are described upon the " upper and
"lower" surfaces respectively, and this mode of description is briefly adhered to
here. A better idea of the topographical relations of the lobes and sulci in the
vermis and the hemispheres may be gained from a study of the divisions of the
cerebellum as if extended in one plane as well as on sagittal sections through
the mesal and lateral planes.
Lobes and Fissures of the Cerebellum.- — The surface of the cerebellum is traversed
by eight more or less curved and deep fissures demarcating nine lobar sub-divisions.
Distinctive names are given to the portions of each lobe in the hemispheres as
contrasted with that in the vermis, although often without warrant, as the two are
quite continuous and merit no such distinction. This burdensome nomenclature
seems so firmly rooted in descriptive anatomy that the various terms must be
repeated here. The arrangement of the fissures and lobes will be understood by
reference to the following schema, in which the structures are named from "before
backward," or cephalo-caudad :
THE CEREBELLUM
897
VERMIS.
p Lingula.
<-
Lobulis centralis.
<-
Culmen monticuli.
<-
Clivus monticuli
Folium cacuminis.
<-
Tuber vermis.
.a
Pyramis.
Uvula
[ Nodulus
HEMISPHERE.
Vincula lingulae.
Precentral Fissure.
Ala lobuli centralis.
Postcentral Fissure.
Anterior crescentic lobe.1
Preclival Fissure. >
Posterior crescentic lobe.
Postclival Fissure. >
Superior semilunar lobe.
Peduncular Fissure. >
j" Inferior semilunar lobe.
•< <: Postgracile fissure.
( Gracile lobe.
Postpyramidal Fissure. >
Biventral lobe.
Prepyramidal Fissure. >
Tonsilla.
Postnodular Fissure. >
Flocculus.
FIG. 582. — Diagram showing fissures on under surface of the cerebellum: F, flocculus; N, nodule;
U, uvula; Py, pyramid; Am, amygdala; Bivent., biventral lobe.
The Lingula (lingula cerebelli) is a tongue-shaped process of the vermis lying in
the ventral cerebellar notch, ventrad of the central lobe, and is partially or com-
pletely concealed by it. It consists of 5, 6, or 7 lamellae lying upon and connected
with the dorsum of the valvula. At either side the lingula gradually shades off,
being prolonged only for a short distance toward the region of the peduncles as the
vincula lingulae.
The Central Lobe (lobulus centralis} is a small median mass situated in the
ventral notch, dorsad of and overlapping the lingula. Its lateral, wing-like pro-
longation is called the ala lobuli centralis.
The Culminal Lobe is much larger than the two lobes just described and con-
stitutes, with the succeeding lobe (the clival lobe), the bulk of the prevermis and
"upper" surface of the cerebellum. It partly overlaps the central lobe. Its
lateral extensions are also termed the anterior crescentic lobes.
i The anterior and posterior crescentic lobes are often called the pars anterior and pars posterior respectively
of the " lobulus quadrangularis."
57
898
THE NERVE SYSTEM
The Clival Lobe is of considerable size, separated from the culminal lobe by
the preclival fissure and from the cacuminal lobe by the postclival fissure. Its
lateral extensions are also termed the posterior crescentic lobes.
The anterior and posterior crescentic lobes of either side have been described
by some writers as the pars anterior and pars posterior of the quadrate lobe or lobulus
quadrangular is.
The Cacuminal Lobe (folium vermis; superior semilunar lobe) is a short, narrow
band at the dorsal margin of the vermis, which expands in either hemisphere
into a lobe of considerable size, of semilunar shape, and bounded caudad by the
peduncular fissure.
The Tuberal Lobe is of small size in the region of the postvermis, but laterally
spreads out into the large inferior semilunar (lobulus semilunaris inferior] and
gracile lobes demarcated by the intervening postgracile fissure. These lobes com-
prise at least two-thirds of the "inferior" surface of the cerebellar hemispheres.
Anterior
crescentic lobe.
Ala Jobidi centralis.
Lingula.
Superior peduncles
of cerebellum.
Great,
horizontal
fissure.
Slender lobe.
A mygdala.
Module. Fourth ventricle.
FIG. 583. — Sagittal section of the cerebellum, near the junction of the vermis with the hemisphere.
(Schafer.)
The Gracile Lobe is often divided by an intragracile fissure into pre- and post-
gracile lobes.
The Pyramidal Lobe is a conical projection, forming the largest prominence
of the postvermis. It is continued laterad into the hemisphere as the biventral
lobe (lobulus biventer] ; the demarcation between the latter and the pyramis proper
is accentuated by the deep sulcus valleculae.
The Uvular Lobe (uvula vermis} occupies a considerable portion of the post-
vermis as the uvula, while its lateral extension in either hemisphere, the tonsilla
or amygdala (tonsilla cerebelli], is a rounded mass lying in a deep fossa between
the uvula and biventral lobe. (This fossa was termed, by the older anatomists,
the nidus avis or "bird's nest" [Reil and Vicq d'Azyr].) The junction of uvula
and tonsilla is an attenuated isthmus marked by a few shallow furrows and
termed the furrowed band.
The Nodular Lobe comprises the nodulus (nodulus vermis) (in the postvermis)
and the flocculus (floccuh secondarii) of each side, connected by a delicate lamina
of white matter, the velum. Each flocculus lies adjacent to the ventro-lateral sur-
face of the peduncular mass, extending into the ventral extremity of the pedun-
THE CEREBELLUM
899
cular fissure. The flocculi of the two sides are connected with each other by a
hand of white matter, termed the velum (posterior medullary velum] in its medial
portion, while its lateral expansions toward the flocculi are termed the peduncles
of the flocculi.
The Internal Structure of the Cerebellum. — In any section of the cerebellum we
may recognize the interior white substance, corpus medullare (medullary body], and
the peripheral gray cortex. The white substance in each lateral hemisphere is more
bulky than in the median vermis, while the cortex is of more uniform thickness
throughout. In a sagittal section in the mesal plane the central white core is seen
to divide into two main branches, preramus and postramus; these main branches
Med.sp
FIG. 584. — Diagram showing the origin and course of the fibres of the peduncles of the cerebellum.
(Edinger.)
divide and subdivide into a series of medullary laminae surmounted by the foliated
cortex, and presenting the characteristic appearance known as the arbor vitae
cerebelli.
Isolated Gray Masses or Nuclei of the Cerebellum. — Embedded in the white
matter of the cerebellum are several gray masses. They are four in number on
1 .j tS J J
each side:
1. Dentatum or dentate nucleus.
2. Embolus or nucleus emboliformis.
3. Globulus or nucleus globosus.
4. Fastigatum or nucleus fastigii.
9CO
THE NER VE SYSTEM
The dentatum is the largest and best studied of the cerebellar nuclei. It is
located in the mesal part of the corresponding cerebellar hemisphere, in the direct
prolongation of the prepedunculus, which appears to enter it. It consists of a
folded lamina of gray matter convoluted like the similar nucleus of the olive, and
opens cephalo-mesad where its hilum (hilus nuclei dentati) permits of the entrance
and exit of fibres from various sources.
The embolus is a small mass of gray substance, elongated cephalo-caudad, and
placed entad of the dentatum, partly covering its hilum.
The globulus consists of several small round or oval masses connected with each
other and lying entad of the preceding.
The fastigatum (nucleus of the "roof") is second in size to the dentatum, situated
close to the mesal plane directly dorsad of the fourth ventricle, or in the fastigium
of the cerebellum, and within the postvermis. The nuclei of opposite sides
approach each other so nearly as almost to fuse.
FIG. 585. — The peduncles of the cerebellum. On the left the three peduncles have been cut at their
entrance into the cerebellum; on the right side they are shown penetrating the cerebellar hemisphere.
(Poirier and Charpy.)
The Cerebellar Peduncles. — Three pairs of peduncles constitute the chief avenues
for the entrance and emergence of the fibres composing the white substance of
the cerebellum and connecting adjacent parts of the brain-stem therewith. The
peduncles are, on each side, the prepeduncle, medipeduncle, and postpeduncle.
The Postpeduncle (corpus restiforme) is the continuation of the restis of the
oblorigata. It contains both afferent and efferent fibres, connecting the cerebellar
cortex with structures situated ca"udad: (1) The dorsal or direct spino-cerebellar
tract, composed of axones arising in Clarke's column (spinal cord) and terminating
in the cortex of the prevermis on both sides of the median line, but chiefly on the
opposite side. (2) The olivo-cerebellar tract, composed of axones arising in the
(inferior) olivary nuclei — principally from the contralateral or opposite olive, and
terminating in the cortex of the prevermis and adjacent hemispheral portions, as
well as in the dentatum. (3) External arcuate fibres from the homo-lateral and
contralateral nuclei of the gracile and cuneate funiculi. (4) The nucleo-cerebellar
THE CEREBELLUM 901
tract, composed of axones from the recioient nuclei of certain cranial nerves
(vestibular, trigeminal). (5) The cerebello-spinal (descending) tract, terminating
in relation with the ventral-horn cells at various levels of the spinal cord.
The Medipeduncles (brachia pontis) are the largest of the three pairs. They
consist of a mass of curved fibres comprising the pons and entering either cerebellar
hemisphere between the parted lips of the ventral end of the peduncular fissure,
just ectad of the postpeduncle. Each peduncle contains axones coursing in oppo-
site directions and in large part may be considered as purely commissural fibres.
Some of the axones terminate, however, in the nuclei pontis to convey impulses
so the cells therein; these in turn send their axones (tractus pontocerebellares)
into the opposite medipeduncle, and therefore constitute interrupted commissural
systems. A few fibre-systems in the medipeduncles establish relations with
certain other structures in the brain-stem, notably the nuclei of the oculomotor,
trochlear, and abducent cranial nerves.
The Prepeduncles (brachia conjunctiva) emerge cephalad from the cerebellum
entad of the medipeduncles. As they extend cephalad they converge to form the
lateral boundaries of the fourth ventricle and partly roofing it in. On trans-section
they appear of oval outline, somewhat
concave toward the cavity of the ventricle.
The valvula, a thin lamina of white sub-
stance, spans the interval between the con-
verging prepeduncles, and thus completes
the roofing-in of the cephalic portion of
the fourth ventricle.
The prepeduncles consist almost wholly
of axones arising from the cells of the
dentatum, the ectal part of the fastigatum
of the same side, and mesal part of the
fastigatum of the opposite side. In their
course, converging cephalad, these bun-
dles pass into the tegmentum of the mid-
brain ventrad of the quadrigemina, and
decussate almost wholly. The fibres of
each peduncle terminate in the rubrum
(red nucleus-) of the opposite side, although FlG- 58&--s™l£*%eT ^S"0 cerebellar
a few continue to enter the thalamus.
This system of fibres is also called the tractus cerebello-tegmentalis, and axones
of inverse functional direction have been included therein.
The Ventral spino-cerebellar tract (Gowers' tract) is in relation with the prepeduncle
and valvula. Unlike the dorsal or direct spino-cerebellar tract, it does not enter the
cerebellum along the postpeduncle. Its fibres pass farther cephalad, through the
reticular formation of the pre- and postoblongata, to become reflected dorso-
caudad at the level of the isthmus of the hind-brain, and entering the valvula,
proceed with the prepeduncle into the cerebellum.
The Medullary Vela. — These are two thin, relatively undeveloped laminae of
white substance, representatives of the mid-dorsal wall of the brain-tube adjacent
to the cerebellar proton, and in the adult brain appear as prolongations of the
white central core of the cerebellum. They are the valvula (anterior or superior
medullary velum; valve of Vieussens) and the velum (posterior or inferior medul-
lary velum).
The Valvula is a thin lamina of white substance spanning the interval between the
converging prepeduncles, and with these assisting in the formation of the "roof"
of the fourth ventricle. Caudad it is continuous with the white substance of the
cerebellum, while on its dorsal surface lie the five to seven folia of the lingula.
902 THE NERVE SYSTEM
Cephalad it narrows as the quadrigemina are approached, and a slight median
ridge, the frenulum, descends upon the dorsal surface of its apical portion from
between the postgemina; on either side of the frenulum may be seen the super-
ficial root of the trochlear nerve. The majority of the fibres in the valvula are
longitudinal; as already described (p. 901), the ventral spino-cerebellar tract
reaches the cerebellum along the valvula.
The Velum is a still thinner lamina of white substance which bears the same rela-
tions to the nodulus that the valvula presents to the lingula. Laterad it extends
to the flocculus of either side. The velum ends in a free crescentic edge and its
endymal and pial coverings continue as a fused, delicate membrane, the metatela.
The valvula and velum enter the cerebellum at an acute angle, forming the
peaked roof (fastigium), while the tent-like recess is called the recessus tecti.
The Fibres Proper of the Cerebellum.— The fibrae propriae of the cerebellum are
of two kinds: (1) commissural fibres, which cross the middle line to connect the
opposite halves of the cerebellum, some at the anterior part and others at the
posterior part of the vermis; (2) association fibres, which are homo-lateral fibres
connecting adjacent laminae with each other.
Microscopic Appearance of the Cerebellar Cortex. — The cerebellar cortex, on
section, presents two marked layers: an outer, of a pale-gray color, the molecular
layer, and an inner, of a rusty-brown tint, the granular layer. At the contact line
of these two layers, but more within the molecular than the granular, are found
the characteristic nerve-elements of the cerebellum, the flask-shaped Purkinjean
nerve-cells.
The Molecular or Ectal Layer consists of cells and delicate fibrillse embedded in a
neuroglial network. The cells are small and are characterized by the course of
their branching axones which run parallel with the surface of the folium, give
off numerous collaterals which pass in a vertical direction toward the cell-bodies
of the Purkinjean elements and embrace these in a basket-like network. Hence
these cells are called basket-cells (Fig. 587).
The Purkinjean Cells are flask-shaped, and form a stratum at the junction of
the molecular and granular layers, their bases directed toward the latter. Each
cell gives off an axone entad, while ectad it gives off numerous dichotomously
branching dendrites covering a very large field of the molecula'r layer. The axone,
after giving off several collaterals which pass toward different parts of the granular
layer, becomes myelinic not far from the cell-body and passes into the white sub-
stance to establish connections with other folia within the cerebellum or with
more distant brain-structures.
The Granular or Ental Layer is characterized by containing numerous small nerve-
cells or granules of a reddish-brown color, together with many nerve-fibrils. Most
of the cells are nearly spherical and provided with short dendrites, which spread
out in a spider-like manner in the granular layer. Their axones pass outward
into the molecular layer, and, bifurcating at right angles, run horizontally for
some distance. In the outer part of the granular layer are also to be observed
some larger cells, of the type termed Golgi cells (Fig. 587). Their axones undergo
frequent division as soon as they leave the nerve-cells, and pass into the granular
layer, while their dendrites ramify chiefly in the molecular layer.
Finally, in the gray substance of the cerebellar cortex fibres are to be seen which
come from the white centre and penetrate the cortex. The cell origin of these
fibres is unknown, though it is believed that it is probably in the gray substance of
the spinal cord. Some of these fibres end in the granular layer, by dividing into
numerous branches, on which are to be seen peculiar moss-like appendages; hence
they have been termed by Ramon y. Cajal the moss-fibres (Fig. 587) ; they form
an arborescence around the cells of the granular layer. Other fibres derived
from the medullary centre can be traced into the molecular layer, where their
THE CEREBELLUM
903
branches cling around the dendrites of Purkinje's cells, and hence they have been
named the clinging or tendril fibres (Fig. 587).
The cerebellum is an important senso-motor organ, transmuting sensor
impressions into motor impulses under the dominance of the cerebral centres.
Its connections with other brain portions and the spinal cord are established by
the peduncular fibres. It is essentially an apparatus for the coordination of
movements and the orientation of the body and its parts in space. These func-
tions depend principally upon the reception of sensor impulses from (1) the
PURKI NJEAN CELL
AXONC OF
GRANULE CELL,
CUT TRANS-
VERSELY
SMALL CELL
OF MOLECULAR
LAYER
BASKET CELL
^MOLECULAR
LAYER
GOLGI CELL
GRANULAR
LAYER
! AXONE OF
'PURKINJEAN
CELL
'TENDRIL FIBRE
'MOSSY FIBRE
FIG. 587. — Trans-section of a eerebellar folium. (Diagrammatic after Cajal and Kolliker.)
NEUROGLIA
CELL
vestibular nerve and (2) the spino-cerebellar (ascending) tracts. Motor impulses
pass along (1) the cerebello-spinal (descending) tracts to the ventral-horn nuclei
of the cervical cord; (2) the tractus rubro-spinalis, which arises in the rubrum
(red nucleus) — an intercalated ganglionic mass connected with the eerebellar
cortex by the prepeduncles, or tractus cerebello-tegmentales. The tractus
rubro-spinalis is a tract for voluntary motor impulses next in importance to the
pyramidal tract.
Weight of the Cerebellum. — Its average weight in the male is 165 grams and
155 grams in the female. It attains its maximum between the twenty-fifth and
904
THE NERVE SYSTEM
thirty-fifth years, its increase in weight after the fourteenth year being relatively
greater in the female than in the male. The proportion between the cerebellum
and the cerebrum is as 1 to 7.5; among eminent men it is 1 to 8.5. In the new-
born the ratio is as 1 to 20.
The Mid-brain (Mesencephalon) .
The mid-brain is the short and constricted portion of the brain which lies in
the opening of the tentorium cerebelli (incisura tentorii) and which connects the
pons with the inter-brain and hemispheres, and hence it is frequently called
the isthmus cerebri. It is developed from the second brain-vesicle, the cavity of
which becomes the aqueduct. It comprises the crura cerebri, the quadagemina,
FRENULUM
TROCHLEAR NERVE
VALVULA (CUT)
CUNEATE TUBERCLE
TUBERCULUM CINERE .'
T/EINIA PONTIS
TRIGEMINAL NERVE
FACIAL NERVE
ACOUSTIC NERVE
GL03SOPHARYNGEAL
AND VAGUS NERVES
HYPOGLOSSAL NERVE
ACCESSORY NERVE
FIG. 588. — The brain-stem, showing oblongata, pons, mid-brain, and part of the thalami.
the geniculate bodies, and the aqueduct. Its two surfaces are ventral and dorsal.
They are free, but concealed : the ventral surface by the apices of the temporal lobes
which overlap it ; the dorsal, by the overhanging cerebral hemispheres. The ventral
surface, when exposed by drawing aside the temporal lobes, is seen to consist of
two cylindrical bundles of white substance, which emerge from the pons and diverge
as they pass forward and outward to enter the inner and under part of either hemi-
sphere. They are the crura cerebri, and between them is a triangular area, the
intercmral space; near the point of divergence of the crura the roots of the third
nerve are seen to emerge in several bundles from a groove, the sulcus oculomotorius
(sulcus nervi oculomotorii) (Fig. 551). The dorsal surface is not visible until a
considerable portion of the cerebral hemispheres and other overlying structures
have been removed. It then presents four rounded eminences placed in pairs,
two cephalad and two caudad, and separated from one another by a crucial
THE MID-BRAIN 905
depression. These are termed the quadrigemina (tubercula quadrigemina') (Fig.
,">ss). The ventral and dorsal surfaces meet on the side of the mid-brain, and are
separated from each other by a furrow, the lateral groove (sulcus lateralis mesen-
cephali}, which runs caudo-cephalad (Fig. 588).
External Morphology. — Dorsal Surface. — The quadrigemina are four rounded
eminences placed in pairs separated by a flat median groove and a more sharply
cut transverse furrow. The cephalic pair, the pregemina (superior colliculi; the
nates of older authors), are the larger and the epiphysis rests in the flattened
depression between them. The pregemina are oval, their long diameter being
directed cephalo-laterad, and are of a yellowish-gray color. The postgemina
(colliculi inferiores; the testes of older authors) are hemispherical in form, and
lighter in color than the preceding. The lamina quadrigemina, comprising the
whole of the dorsal wall of the mid-brain, extends from the root-region (post-
commissure) of the epiphysis to the cephalic end of the valvula.
Each pre- and postgeminum is continued latero-ventrad in prominent white
bands, the brachia. The band from the pregeminum is termed the prebrachium ;
that from the postgeminum is called the postbrachium.
The Prebrachium (brachium quadrigeminum superius) proceeds cephalo-ventrad
between the overhanging pulvinar and a light-gray eminence, the postgeniculum.
In reality it is a continuation of a part of the optic tract. The Postbrachium
(brachium quadrigeminum inferius) proceeds in a similar direction to disappear
beneath the postgeniculum.
Of the two geniculate bodies, on either side, the pregeniculum belongs rather
to the thalamus, while the postgeniculum may properly be considered here among
the structures of the mid-brain.
The Postgeniculum (corpus geniculatum mediale s. internale] is a small oval
eminence on the lateral surface of the mid-brain in which the mesal root of the
optic tract appears to terminate. The postbrachium likewise appears to run into
this body; as a matter of fact, so far as is known, the postgeniculum is (1) a way-
station for auditory impulses in their course toward the cerebrum; (2) the origin
and terminus for the arched commissure of Gudden (infracommissure; commissura
inferior [Guddeni]), by means of which circuitous path, through the chiasm, and
along the mesal root of optic tract, the postgenicula of the two sides are con-
nected.
The quadrigeminal lamina is continuous caudad with the cerebellar pre-
peduncles and the intervening valvula. A slight, median, ridge-like projection,
the frenulum valvulae, descends from between the postgemina onto the valvula;
on either side of the frenulum emerge the slender trochlear nerves.
The Crura constitute the bulk of this portion of the brain-stem. Upon the
ventral aspect of the brain they appear as two large, white, rope-like strands emerg-
ing from the pons and diverging to either cerebral hemisphere, becoming embraced
by the optic tracts. Each crus is composed of a dorsal tegmental part — a continua-
tion of the tegmentum of the hind-brain — and a ventral crusta or pes. These parts
are demarcated from each other on the external surface by the oculomotor sulcus
ventrad (which looks into the intercrural space) and the sulcus lateralis mesen-
cephali on the lateral aspect. The lateral surface shows dorsally the cerebellar
prepeduncle dipping into the substance of the mid-brain, while between it and the
crusta is a small triangular field of oblique fibre-strands, not always well defined,
called the trigonum lemnisci because the lateral lemniscus tends to reach the sur-
face of the brain-stem at this situation (Fig. 588).
The surface of the crura shows a rope-like twist in the course of its fibre-bundles.
Oblique or transverse fasciculi are sometimes seen upon the surface, two of
which are fairly constant. They are (1) the taenia pontis, and (2) Gudden's
tractus peduncularis transversas (cimbia).
906
THE NERVE SYSTEM
The Taenia Pontis, as Horsley has shown, takes origin contralaterally in the
gray substance continuous with the "interpeduncular ganglion," but ventral to it.
The ta?nia then passes over the lateral lemniscus and cerebellar prepeduncle to
the dentatum and fastigatum.
The Cimbia1 or Tractus Peduncularis Trans versus may he traced from the pre-
geminum and postgeniculum over the surface of the crus to near the ventro-meson,
disappearing from view in the oculomotor sulcus.
AQUEDUCT
NUCLEUS OF
OCULOMOTOR
NERVE
POSTBRACHIUM
MEDIAL LONGI-
TUDINAL FASCIC-
ULUS
OCULOMOTOR
NERVE
FIG. 589. — Trans-section of the mid-brain through the level of the pregeminum.
Internal Structures of the Mid-brain. — If a cross-section be made through
the mesencephalon it will be seen that each lateral half is divided into two unequal
portions by a lamina of deeply pigmented gray substance, named the substantia
nigra (intercalation; ganglion of Soemmering). The postero-superior portion of
the crus is named the tegmentum, and the antero-inferior the crusta or pes. The
substantia nigra is curved on section with its concavity upward, and extends from
MESENCCPHALIC ROOT
OFTRIGEMINAL NERVE
NUCLEUS OF
TROCHLEAR NERVE
LATERAL LEMNISCUS
MEDIAL LONGITUD-
INAL FASCICULUS
DECUSSATION OF
CEREBELLAR PED-
UNCLES
MEDIAL
LEMNISCUS
FIG. 590. — Trans-section of the mid-brain through the level of the postgeminum.
the lateral groove externally to the oculomotor sulcus internally. The two
crustse are in contact in front of the pons, from which point they diverge from each
other, but the two halves of the tegmentum are joined to each other in the mesal
1 In architecture — a band or fillet about a column. Also called fasciculus arciformis pedis.
THE MID-BRAIN 907
plane by a forward prolongation of the raphe or median septum of the pons.
Laterally the tegmenta are free, but dorsally they blend with the quadrigemina.
Traversing the mid-brain in the median plane and nearer the dorsal surface is
the aqueduct, surrounded by the central tubular gray, which in this brain-segment
has retained the comparatively primitive arrangement of the embryonic brain-tube.
The Aqueduct (Mexoccle) and Central Gray Aqueduct. — The aqueduct is a nar-
row canal connecting the third with the fourth ventricle, and demarcating the
lamina quadrigemina dorsad from the tegmental zone. Its shape on trans-section
varies at different levels, being T-shaped caudad, oval or quadrangular along its
middle, and triangular cephalad. It is lined by the endyma (columnar ciliated
epithelium) and surrounded by the central aqueduct gray. The central gray is
separated dorsally from the quadrigemina by the stratum lemnisci; ventrad near
the median plane lie the medial longitudinal bundles. Within the gray substance
lie certain well-defined cell-clusters, the nuclei of origin of the oculomotor and
trochlear nerves and the mesencephalic root of the trigeminal nerve. These
will be described in detail later.
The Substantia Nigra or Intercalatum. — The substantia nigra is a crescentic
layer of deeply pigmented gray substance interpolated between the crusta and
the tegmentum. Mesad it nearly touches its fellow of the opposite side, being
separated by the rudimentary ganglionic gray (the postperforatum) in the inter-
crural space. Its ventral face sends numerous ramifying prolongations among
the fasciculi of the crusta. It extends from the cephalic border of the pons to
the subthalamic region, while its lateral edge reaches the surface along the lateral
sulcus. Its cells are medium-sized, multipolar, their bodies approaching the
fusiform, or angular in outline. The cells are characterized by a pigment (marked
only in man) which varies from a pale brown in the young to an absolute blackness
in the very aged. The axones arising from the cells proceed in various directions
toward the tegmentum and cruita, but their exact course is not known. Experi-
mental excitation of this ganglionic mass elicits movements of deglutition accom-
panied by respiratory changes. Mellus has found in the monkey that a portion
of the pyramidal tracts is interrupted in the substantia nigra.
The Quadrigemina. — The quadrigemina are largely composed of gray substance,
but the pre- and postgemina differ distinctly in structure.
The Pregeminum presents a true cortical type, which is more evident in the optic
lobes of lower vertebrates. In man the thin, outermost white layer — the stratum
zonale — is an expansion of the optic tract. Beneath this lies a gray nucleus, with
numerous small cells — the stratum cinereum — a cup-like layer of crescentic outline
on trans-section. The succeeding ental layer is a white stratum, also derived
from the optic tract — the stratum opticum. Between this and the underlying
stratum lemnisci is a second gray layer, less defined because of the diffuse inter-
lacing of white fibres.
Each pregeminum is one of a series of primary centres of vision related more
to eye-muscle reflexes resulting from optic and auditory stimuli than to actual
light and color perception. Fibres from the retina, for the most part, form the
stratum zonale and end in the ganglionic gray; others enter into the formation
of the stratum opticum. Return fibres from the occipital cortex also enter the
stratum opticum. The retinal and occipital fibres determine the formation of the
prebrachium. Other fibres reach the pregeminum through the lateral and
medial lemnisci — from both sides — to end in relation with the deeper cells of the
stratum cinereum. The connections of the pregeminum with the cochlear centres
afforded by the lateral lemniscus establishes the so-called optic-acoustic reflex path.
The Postgemina are more homogeneous in texture, comprising a pair of compact
ganglia which on trans-section have the shape of biconvex lenses, encapsulated by
white substance. The cells are small, multipolar, and very numerous, embedded
90S THE NER VE SYSTEM
in a fine molecular groundwork. The white stratum zonale is principally derived
from the fibres of the lateral lemniscus, which terminate in the central gray of the
postgeminum as well as in the postgeniculum. The axones of the cells in the
postgeminum course cephalad in the postbrachium, dip beneath the postgenicu-
lum into the tegmentum and proceed to the thalamus. The postgemina are im-
portant links in the chain of the auditory neurone system, and are special localities
for the reflexion of auditory impulses.
The Tegmentum. — The tegmentum of the mid-brain is continuous with the
like formations in the hind-brain stem and consists of longitudinal fibre-bundles
intersected by transverse arched fibre-systems with gray substance irregularly
scattered in the interstices, composing the formatio reticularis. In its ventral por-
tion, on either side, and at the level of the pregeminum, lies a gray ganglionic
mass, the rubrum or red nucleus, (nucleus tegmenti; nucleus ruber}.
The Rubrum or Red Nucleus, so termed from its reddish tinge in the fresh brain,
which it owes to the pigmentation of its cells as well as to its great vascularity, is
found subjacent to the pregemina in those section-levels where the substantia nigra
has its greatest expansion. In trans-sections its outline is irregularly circular; in
sagittal sections an elongated oval. The rubrum is the end-station for the majority
of the decussated cerebellar prepeduncle fibres, for fibres from the cerebral cortex,
and from the striatum. These fibre-bundles form for the nucleus a' capsule
which is thicker on its ectal surface. From'the cells of each rubrum arise axones
which pass (1) to thalamus and cerebral cortex (links in the cerebello-cortical
neurone-chain), and (2) axones which descend into the spinal cord to form the
tractus rubrospinalis (Monakow's) — a continuation of an indirect motor path from
the cerebral cortex to peripheral motor nerve. The tracts arising from the red
nuclei of the two sides decussate with each other and descend in the tegmentum.
In the intercrural space lies a primitive gray ganglionic mass, the postperfo-
ratum. Cephalad of the pons, in the median line, lies a cluster of cells, the inter-
peduncular ganglion (Gudden). The fasciculus retroflexus (Meynert), whose fibres
arise in the habenal ganglion, descends to end in the interpeduncular ganglion.
The principal longitudinal fibre-tracts in the tegmentum of the mid-brain are
(1) the medial longitudinal fasciculus, (2) lateral lemniscus, (3) medial lemniscus,
(4) the decussating cerebellar prepeduncles, (5) the decussating rubro-spinal tracts,
and (6) the central tegmental tracts.
The Medial Longitudinal Bundle lies on each side of the median plane, lying
ventrad of the central aqueduct gray in the mid-brain and continuous throughout
the brain-stem in its formatio reticularis. It is the continuation and the equiva-
lent, but in a more differentiated form, of the ventral basis bundle of the spinal
cord. It is formed by association neurones and acts as an associating agent with
regard to many cranial and spinal-nerve centres for the performance of certain
definite functions. Its neurones receive impulses from afferent elements and
transmit them to motor or efferent elements. It particularly brings into relation
the sensor cranial-nerve nuclei and the quadrigemina with the motor nerves of
the eye (III, IV, and VI), of the face (VII), and of the trunk. A special nucleus
for the bundle is described as being situated in the gray floor of the third ventricle,
at its junction with aqueduct. The axones from the cells of this nucleus cross
to the opposite side through the postcommissure (Fig. 591).
The Lateral Lemniscus, we have learned, is a continuation of the auditory path
in its course to the cerebral cortex. Its formation is described on p. 888. In the
mid-brain the fibres of the lateral lemniscus course through the lateral part of
the tegmentum, near the surface, and most of them end in the postgeminal gray
nucleus and in the postgeniculum. A few fibres are.carried into the pregeminum.
The Medial Lemniscus, or principal conduction path for sensor impulses from
the trunk and extremities, and already discussed in the preceding (p. 888), ascends
THE MID-BRAIN
909
in the tegmentum of the mid-brain in the contact-zone with the crusta. In its
ascent it is deflected slightly dorso-laterad by the red nucleus. The lateral border
of the ribbon-like bundle is in contact with the lateral lemniscus, and forms an
angle with it, as seen on trans-sections (Figs. 589 and 590) .
Many of the fibres of the medial lemniscus terminate in the pregeminum; the
remainder proceed to the thalamus.
POSTCOMMISSURE
SPECIAL NUCLEUS
OF THE MEDIAL
LONGITUDINAL
BUNDLE
FOUNTAIN
DECUSSATION
PREGEMINUM
FIG. 591. — The medial longitudinal bundle.
The Prepeduncles of the Cerebellum sink into the mid-brain tegmentum in a
cephalo-ventral direction, the two prepeduncles converging and their fibres under-
going a complete decussation (Wernekinck's commissure) subjacent to the post-
gemina. The crossed fibres end, for the most part, in the rubrum of each side;
others circumvent the nucleus, forming a white capsule for it which is thicker
on its ental surface, and proceed to the thalamus.
The Tractus Rubrospinalis (Monakow's) is composed of axones arising in the
red nucleus, decussating with those of the opposite tract, and descending in
9 10 THE NER VE S YSTEM
the tegmentum to the lateral intermedial fasciculus of the cord, to terminate
in relation with ventral-horn cells.
The Central Tegmental Tract (olivary fasciculus] probably arises in the inferior
olivary nucleus and ascends in the tegmentum. In the pre-oblongata it is best
seen in trans-sections as a compact longitudinal bundle along the dorsi-mesal
aspect of the superior olive. Cephalad it is said to end in the lenticula.
Fountain Decussation.1 — A dense decussation may be found in the space between
the two red nuclei. The fibres composing the decussating bundles arise from
cells in the pregemina and central aqueduct gray. After having crossed the
middle line they descend, join the medial longitudinal fasciculus, and give off
collaterals to, or terminate in the nuclei of the eye-muscle nerves.
The Crusta or Pes. — The crusta or pes is somewhat crescentic in outline
on section and is composed of longitudinal fibre-bundles — the continuation of
the internal capsule — divisible into three sectors. The middle sector comprises
three-fifths of the cross-section area of the crusta, and comprises the pyramidal
tract on its way from the cerebral cortex (motor area) to cranial and spinal
centres below. The ectal sector, or lateral one-fifth, comprises the temporo-
pontile tract;2 its axones arise from cortical cells in the temporal lobe and end
in fine terminal arborizations in relation with cells of the nuclei pontis. The
ental sector, or mesal one-fifth of the crusta, comprises the fronto-pontile tract;
its axones arise from cells in the cortex of the frontal lobe and terminate in
the nuclei pontis.
The Pyramidal Tract is a direct "voluntary" motor tract; the two cortico-pontile
tracts enumerated above are links in a chain of neurones which constitute an
indirect motor tract. The series may be shown in the following order: Cortico-
pontile tract; nuclei pontis; cerebello-cortex; dentatum; pre peduncle; rubrum; tractus
rubrospinalis; spinal gray; spinal nerve; muscle.
Summary of the Gray Masses in the Mid-brain.
* Central aqueduct gray
(a) Oculomotor n. nucleus
(6) Trochlear n. nucleus
Nucleus radicis descendentis nervi trigemini
* Nucleus of medial longitudinal bundle and postcommissure
* Formatio reticularis
* Substantia nigra (intercalatum)
* Rubrum (red nucleus)
* Stratum cinereum pregemini •
* Nucleus postgemini
* " Interpeduncular" ganglion.
Structures marked with an asterisk have been considered in the preceding
description. The central connections of the oculomotor, trochlear, and trige-
minal nerves may now be described.
Deep Origin of Cranial Nerves Arising in the Mid-brain. — The mesen-
cephalic root of the trigeminal nerve has been described on p. 894.
The Trochlear-nerve Nucleus. — The trochlear-nerve nucleus is situated in the
level of the cephalic half of the postgeminum. It is a small oval mass of gray
substance in the ventral part of the central aqueduct gray. The cells are large,
sometimes stellate in appearance. The root fibres pursue a peculiar course;
they accumulate in the latero- ventral angle of the aqueduct gray, run caudad,
gradually rising dorsad, and suddenly turn mesad to undergo a complete decus-
1 Decussaiio fontinalis, so called because of the resemblance of the scattering strands to the jets of a
fountain.
2 Turck's bundle; not to be confused with Tiirck s column m the cord.
PARTS DERIVED FROM THE FORE-BRAIN 9H
sation with the root of the opposite side in the valvula, emerging laterad of the
frenulum, or at the inner border of the prepeduncle.
The nucleus is placed under the dominion of the cerebral cortex by pyramidal
fibres, and it is associated with other nuclei in the brain-stem by the medial
longitudinal bundle.
The Oculomotor-nerve Nucleus.— The oculomotor-nerve nucleus is a group of
cell-clusters in the ventral portion of the aqueduct gray, subjacent to the pregemi-
num, and extending cephalad to become lost in the gray wall of the third ventricle
at the slope formed by the opening out of the aqueduct. Its nerve-elements are
arranged in definite groups. The most cephalic of these is composed of smaller
elements, closely crowded and embedded in deeply staining molecular ground-
substance. In a flat-wise section of the brain-stem the outline of this nucleus
resembles an inverted L or the tip of a boat-hook; the axones from the cells of
this nucleus £of Edinger and Westphal) supply the ciliary muscle and sphincter
iridis (pupillary motion). The main nucleus, composed of several sub-groups, lies
caudo-laterad of the preceding, and is composed of larger cell-elements.
The root-fibre bundles from this nuclear group pass ventrad, breaking through
the medial longitudinal fasciculus, separating like the strands of a horse's tail by
the interference of the red nucleus, to become gathered into more compact bundles
between the mesal edge of the substantia nigra and intercrural region, and emerg-
ing by eight to twelve fascicles which compose the trunk of the oculomotor nerve.
The origin of each nerve is not limited to the nuclei of its side; a part is decussated
and the decussated origin is related to the innervation of the Internal Rectus. By
means of association neurones in the medial longitudinal fasciculus the oculo-
motor and abducens nuclei of one side are brought into relation, affording an
organic basis for the synergism existing between the Internal and External Recti
muscles in the conjugated lateral eye-movements.
The paradox of the facial nerve supplying muscles under the reflex dominion of
the retina (orbicularis oculi) instead of the oculomotor may be explained by the
assumed existence of fibres emerging from the oculomotor nucleus, entering the
medial longitudinal fasciculus and joining the root of the facial.
Parts Derived from the Fore-brain.
The Fore-brain or Prosencephalon includes those portions of the brain which are
derived from the cephalic one of the three primary brain-vesicles. It includes,
according to prevailing schemas, a thalamic portion (the thalamencephalon or
diencephalon) and the telencephalon. The two divisions constitute a structural
continuity and exhibit a mutual dependency so close that the arbitrary distinction
now in vogue tends to mislead. The relations of "diencephalon" and "telen-
cephalon" are further complicated by the intimate fusion of the sides of the former
(thalami) with the floors of the latter (caudatums) ; this caudatothalamic fusion,
in the adult brain, gives rise to some difficulty in distinguishing the two segments.
The internal capsule which intervenes between thalamus and lenticula also inter-
venes between lenticula and caudatum, both telencephalic parts.
External Morphology. — The diencephalon or thalamencephalon comprises the
thalami, the epiphysis and habenae, the pregeniculums, and the pars mammillaris
hypothalami. (Other classifications include also the pars optica, with tuber, chiasm,
and hypophysis. It is also defined as so much of the fore-brain as does not enter
into the formation of the cerebral hemispheres.) Caudad it is continuous with
the mid-brain, cephalad with the cerebral hemispheres. Its primitive cavity
becomes metamorphosed in the adult into the third ventricle or diacele as the
lateral walls hypertrophy to form the thalami. Its ventral surface is the relatively
912
THE NERVE SYSTEM
insignificant gray lamina in the intercrural space. Its dorsal surface is concealed
from view by the massive hemispheres and their great commissure, the callosum,
and by the fornix. Its actual roof, separating it from the overlapping cerebral
parts, is a delicate membranous fold, the diatela or velum interpositum.
The Thalami.1 — The thalami constitute the bulk of this portion of the brain.
They are large ovoid masses of gray substance so named by the ancients after their
resemblance to a pair of couches. Each thalamus is smaller frontad than caudad
and the caudal ends are more widely separated from each other. The mesal or
ventricular surface is largely free, except for an area, of variable size, by which
the two thalami are fused in 90 per cent, of brains. This thalamic fusion is also
called the medicommissure. This surface is covered by endyma and of smooth
contour. Its dorsal limit is marked by an endymal ridge, usually torn through
in dissection, the ripa2 or tsenia thalami, fortified by a subjacent narrow band of
MEDICOMMISSURE
CHOROID PLEXUS OF
THIRD VENTRICLE
TENIA THALAMI
COMMISSURE
POSTCOMMISSURE
ROSTRUM
COPULA
PRECOM-
MISSURE
TERMA
CHIASM
O PT I C
NERVE
HYPOPHYs'lS
FIG. 592. — Mesal aspect of a brain sectioned in the median sagittal plane.
fibres called the stria medullaris, which may be traced to the habenal nucleus
and habenal commissure (or "stalk" of the epiphysis). Caudad lies a depressed
triangular area — the trigonum habenae, situated cephalad of the pregeminum.
The dorsal surface is usually described as being free, but only a narrow ectal
portion can be so described, the endyma of the lateral ventricle being slightly
reflected upon it (the lamina affixa] before entering into the formation of the para-
plexus. The rest of the dorsal surface is not lined by endyma, but is in contact
with the pial fold called the velum interpositum. This surface is of a whitish
color owing to a thin layer of white fibres, the stratum zonale. A faint oblique
groove crosses this surface in a caudo-lateral direction, corresponding to the ectal
1 Thalamos, bed or couch; bed-chamber.
2 The name ripa was proposed by Wilder for the line formed by the rupture of the endyma along the lines
of its reflection from entocoelian (ventricular) surfaces.
PARTS DERIVED FROM THE FORE-BRAIN
913
edge of the fornix. Laterad it is demarcated from the caudatum by a groove
which is occupied by a slender band of fibres and the striatal vein, called the taenia
semicircularis or stria terminalis. The surface is not of even contour throughout,
usually showing three eminences (in addition to the pulvinar) corresponding to
the main nuclear aggregations within the thalamus, viz. :
Tuberculum anterius.
Tuberculum medialis.
Tuberculum lateral is.
PSEUDOCELE
HEM (SEPTUM
PRECOMMISSURC
TENIA THALAMI
TENIA SEMI-
CIRCULARIS
GROOVE CORRE-
PONDING TO
FORNIX
TRIGONUM
HABEN/E
POSTCOM MISSURE
PREGEMINUM
POSTGEMINUM
TROCHLEAR
NERVE
FRENULUM
•VALVULA (CUt)
FIG. 593. — Dissection showing the two thalami, the two caudatums, and adjacent parts.
The Tuberculum Anterius. — The tuberculum anterius forms a marked bulging
frontal extremity, which helps to form the boundary of the porta (foramen of
Monro) or aperture of communication between lateral and third ventricles.
The caudal extremity of the thalamus is a prominent, bolster-like projection
which overhangs the brachia of the quadrigemina and 'is called the pulvinar.
A smaller oval prominence, situated ventro-laterad of the pulvinar, is termed the
pregeniculum (corpus geniculatum externum) — a partial end-station for the optic
tract.
58
914 THE NERVE SYSTEM
The lateral surface of the thalamus is in contact with the internal capsule — that
great concentration of fibre-tracts coursing to and from cerebral centres and
forming the crusta below. To this white stratum the thalamus itself contributes
fibres destined to reach the cortex, and in turn it receives fibres from the cortex.
These thalamo-cortical and cortico-thalamic sets of fibres constitute the thalamic
radiation, forming a more or less distinct reticulated capsular zone (external
medullary lamina; stratum reticulatum) for the thalamus.
The ventral surface is in contact with the sub-thalamic tegmental substance
and continuous with the central gray of the third ventricle lining its sides and floor.
Internal Structure of the Thalamus and its Connections. — The thalamus is com-
posed of gray substance, with large multipolar cells, which is sub-divided into a
number of distinct nuclei; twenty such have been described; three are universally
recognized. They are separated from each other by a white layer (lamina medul-
laris interna] which runs parallel to the wall of the third ventricle for its greater
length; caudally it runs mesad, overlapped by the ectal nucleus, and numerous
sub-laminae run into it. Frontad the internal medullary lamina sub-divides into
two branches, thus permitting the intrusion of the nucleus anterius between the
two main nuclei (medial and lateral}.
The nucleus anterior lies fronto-dorsad ; in it terminate the axones of the fasciculus
thalamomammillaris (fasciculus albicantiothalami — bundle of Vicq d'Azyr}. The
nucleus medialis is lined mesad by the central gray of the third ventricle and is
usually fused with its fellow of the opposite side (medicommissure). A special
spheroidal cell-cluster in this nucleus is called the centrum medianum (Luys).
The nucleus lateralis is the largest of the three, extending the entire length of the
thalamus and including the pulvinar. A special semilunar cluster of cells in the
ventral portion of this nucleus is called the nucleus semilunaris (Flechsig).
The Connections of the Thalamus. — The thalamus is a ganglion interposed
between the sensor tracts in the tegmentum and the cerebral cortex, as well as
an important link in the optic path. It also gives rise to motor tracts con-
cerned with instinctive movements of an emotional nature. It is a relay station
for the various tracts which convey sensations of touch, temperature, and pain
from the body, extremities, head, and neck, of muscle-sense, and of the special
senses. It transmits these impulses to, and, reciprocally, receives impulses from
the cerebral cortex. As an "emotional" centre it is also under the inhibitory
influence of the cerebral cortex, which, if the emotion be not too strong, prevents
its external manifestation.
The thalamo-cortical and cortico-thalamic fibres, with the internal capsule, enter
into the corona radiata or fan-like formation of the white substance of the cerebral
hemisphere. Although there is no anatomic sub-division into distinct groups of
these fibres as they stream to and from the thalamus, it is customary to distinguish
a frontal, a parietal, an occipital, and a ventral stalk. The frontal and parietal
stalks, as their names indicate, pass between thalamus and fronto-parietal cortex,
as well as to the lenticula and caudatum. The occipital stalk is composed of
fibres passing in both directions between the pulvinar and occipital cortex, con-
stituting the so-called optic radiation. The ventral stalk comprises the ansa
lenticularis (thalamolenticular} and the ansa peduncularis (thalamotemporal and
thalamoinsular}. They will be described in detail farther on.
The Pregeniculum is an intercalar ganglion proper to the optic nerve, derived
from the thalamus. On section it is seen to be characterized by the regular
alternation of deeply gray and white laminae. The latter are thicker and com-
posed of fibres which enter the pregeniculum from the optic tract and optic radia-
tion. The nerve-cells in the gray substance are large, multipolar, and pigmented.
[NoTE. — The pregeniculum and the more isolated postgeniculum are gener-
ally included under the head of metathalamus.}
PARTS DERIVED FROM THE FORE-BRAIN 915
The Hypothalamic Tegmental Substance, continuous with the mid-brain tegmen-
tum, is interpolated between the ventral face of the thalamus, the red nucleus,
and a continuation of the substantia nigra known as the corpus hypothalamicus
or body of Luys. Through the hypothalamic tegmentum stream the fibres of
the medial lemniscus, of the cerebellar pre peduncle, and from the red nucleus, to
end in relation with thalamic cells. The corpus hypothalamicus is a grayish-
brown, lentiform mass which lies in the ideal continuation frontad of the lateral
part of the substantia nigra, and, like it, situated between pes and tegmentum. It
is made up of fine myelinated fibres crowded in great profusion and confusion,
with numerous delicate, coiled capillaries and sparse, multipolar, more or less
pigmented, nerve elements of moderate size. The outline of the body is defined
by a white capsule, some of the fibres of which are seen to decussate in the floor
of the third ventricle, with those of the opposite side dorso-caudad of the albicantia.
The Epiphysis (corpus piiieale) (Figs. 592, 593). — The epiphysis (pineal body,
from its shape resembling a fir-cone — pinus) is a small, reddish-gray body placed
between the caudal ends of the thalami and occupying the depression between
the two pregemina. It is covered by the velum interpositum, which intervenes
between it and the splehium of the callosum. It is an outgrowth which is not
regarded as an important neural ingredient of the human brain and is generally
believed to be a rudimentary relic, representing a cyclopean eye1 of some extinct
ancestral vertebrate, homologous with the parietal organ, resembling a molluscan
eye of a living species of lizard (the Hatteria of Australia). Its attached base is
a hollow peduncle divisible into a dorsal and ventral part by the intrusion of the
epiphyseal recess (recessus pinealis] of the third ventricle. The dorsal stalk con-
tinues on either side and upon each thalamus as the stria medullaris; it is reen-
forced by commissural fibres joining the habenee of the two sides; hence another
name for the dorsal stalk is the habenal commissure (supracommissure of Osborn).
The ventral stalk is folded over another commissural band — the postcommissure.
Structure. — The epiphysis, or pineal gland, consists of a number of follicles,
lined by epithelium, and connected together by ingrowths of connective tissue.
The follicles contain a transparent, viscid fluid, and a quantity of sabulous matter
named brain sand (acervus cerebri), composed of phosphate and carbonate of
lime, phosphate of magnesia and ammonia, with a little animal matter. These
concretions are almost constant in their existence, and are present at all periods
of life.
In the interval between the epiphysis and the caudal end of the thalamus lies
a small triangular depression (sometimes an elevation) known as the trigonum
habenae, marking the position of the nidus or ganglion habenae, a group of small
angular cells. The axones from these cells are collected ventrad into the fasciculus
retroflexus (Meynert), which courses through the tegmentum mesad of the red
nucleus to end in the interpeduncular ganglion (Gudden) in the postperforatum
In addition to this fasciculus, the habena is the reunion point for two other sets
of fibres: (1) the stria medullaris and (2) the habena proper or habenal commissure.
The stria medullaris (p. 912) is made up of axones arising from two sources:
(1) cells in the hippocampus (via fornix) and (2) cells in the ganglion opticum
basale. These join near the fornicolumn (anterior pillar of fornix) and run
caudad on the mesal thalamic surface, to end in the habenal ganglion of the same
side and, by crossing in the dorsal stalk of the epiphysis form the habenal com-
missure, ending in the corresponding nidus habenae of the opposite side.
Postcommissure. — The postcommissure is a round band of white fibres crossing
from side to side in the ventral stalk of the epiphysis bridging the aqueduct at
i Although most vertebrates show a single epiphysis or parietal organ, it is double in the lamprey and cer-
tain reptiles; the two epiphyses lie one in front of the other — not side by side (although probably paired
organs originally). The frontal organ sends its fibres into the habenal nucleus; the caudal organ to the
region of the postcommissure (tectum opticum).
916 THE NERVE SYSTEM
its continuation into the third ventricle. The postcommissure shares relation
with both fore- and mid-brain structures and is formed of decussating fibres
which may be enumerated in the following systems: (a) fibres arising in the special
nucleus (described on p. 908) for the medial longitudinal bundle; (6) fibres connecting
the two thalami; (c) fibres connecting the habenal nidi; (d) fibres connecting the
pregemina.
[NOTE. — The habense, epiphysis, and postcommissure are generally included
under the head of epithalamus.]
The Postperforatum (locus perforate posticus). — The postperforatum has been
described on p. 861. It marks the situation of the " interpeduncular ganglion,"
small in man, but very large in rodent brains. From the cells in this primitive
gray lamina arise the fibre-tracts already described as the taenia pontis (p. 906),
and often visible at the point of emergence from the gray substance of the inter-
crural space.
The Albicantia (Fig. 592). — The albicantia or mammillaria are two symmetrical,
small, round, white protuberances situated side by side in the intercrural space
cephalad of the postperforatum, at a point where the floor of the third ventricle
rapidly decreases in thickness to form the tuber. The color of each albicans is
white, owing to a superficial stratum of fibres derived from the fornix. Within lie
three nuclear masses: two medial, constituting the main mass, and a smaller
lateral nucleus applied against the former, so as to represent a crescent on cross-
section.
The fibres of the fornix terminate in the albicans. From its cells arise two
fasciculi which have a common neurone origin. Cajal discovered, and Kolliker
confirmed the fact, that the axones from the medial nucleus cells bifurcate; one
set of limbs passes fronto-dorsad to form the fasciculus thalamomammillaris
(bundle of Vicq d'Azyr), which ends in the nucleus anterius of the thalamus, while
the other set of limbs of the primary axones passes caudad to form the fasciculus
pedunculomammillaris in the mid-brain tegmentum; its destination is doubtful.
The axones from the lateral nucleus join the latter bundle.
[NOTE. — The postperforatum and the albicantia are generally included under
the head of the Pars Mammillaris Hypothalami.]
Third Ventricle (ventriculus tertius) (Fig. 592).— The third ventricle is the adult
representative of the cavity of the primary fore-brain vesicle, but only so much of it
as is not carried laterad, on either side, in the rapidly growing, eventually huge
cerebral hemisphere buds to form the lateral ventricles. It is a narrow, cleft-like
interval between the two thalami and hypothalamic gray, limited frontad by the
terma, continuous caudad with the aqueduct and laterad, through the portse,
with the lateral ventricles. Its roof is destitute of nerve tissue and is formed
by a delicate, fused endymal and pial layer, invaginated on either side of the
median plane by paraplexuses. The pial layer is one of the constituents of
the fold known as the velum. The floor of the ventricle is formed by structures
already described on the basal aspect in the intercrural space, viz., the tuber,
albicantia, and postperforatum, as well as the chiasm and a portion of the teg-
mentum of the crura. Much of the floor, it may be noted, is formed by the
primitive, undifferentiated central gray; and although the optic vesicle developed
from its ventro-cephalic portion, the caudal shifting of central optic connections
to thalamus and mid-brain has made this portion of the neural tube wall com-
paratively insignificant. The lateral walls are formed, in part by the thalami, in
part by the hypothalamic gray ventral extension. The fornix may be seen, shining
through a thin lamina of gray substance and the endyma, coursing caudo-ventrad
to the albicans. A slight furrow, the aulix or sulcus of Monro, may sometimes be
traced from the aqueduct to the porta, curving ventrad of a bridge-like fusion of
the two thalami — the medicommissure. (The latter term is inappropriate, as no
PARTS DERIVED FROM THE FORE-BRAIN 917
commissural fibres appear to pass from one thalamus to the other in this "thalamic
fusion;" it is absent in about 10 per cent, of brains examined.)
The cephalic wall is formed by the terma, the rudimentary median-cephalic
wall of the neural tube. The terma is attached to the dorsum of the chiasm;
dorsally it is reenforced by the precommissure.
As seen in mesal section or as shown by a cast of the ventricle (Fig. 592)
it is seen to be of irregular outline. Frontad is the optic recess, dorsad of the
chiasm; caudad thereof is the infundibular recess in the tuber. The epiphyseal
recess is seen between the habenal commissure and the postcommissure. Dorsad
of the epiphysis is a diverticular recess of variable extent (recessus suprapinealis).
If the segmentation of the fore-brain into two divisions be adopted ultimately,
it will be necessary to allot one portion of the third ventricle (between the thalami)
to the diencephalon (hence diacele), and the rest to the telencephalon (the medial
cavity of which is termed the aula by Wilder).
In anticipation of the description of the cerebral hemispheres we may consider
here the remaining structures in the floor of the third ventricle, usually included
under the head of the pars optica hypothalami of the telencephalon, in order to lead
up to a description of the cerebral connections of the optic tract.
External Morphology of the Optic Portion of the Hypothalamus. — This
includes the tuber and hypophysis, the terma, the chiasm, and the optic tracts.
The Tuber (tuber cinereum) (Fig. 592). — The tuber is a thin-walled conical pro-
jection in the intercrural space cephalad of the albicantia. Its apical portion is
attenuated to form the stalk of the hypophysis ; this is generally termed the infundib-
ulum, while the cavity of the funnel-shaped diverticulum is called the infundibular
recess of the third ventricle. The gray lamina composing the tuber is continuous
with the central ventricular gray, and therefore with the terma.
The Hypophysis. — The hypophysis is a structure of two-fold origin, giving rise
to a division into a prehypophysis and a posthypophysis. The posthypophysis
alone is of neural origin, developing as a ventral diverticulum from the primitive
neural tube. The prehypophysis develops from the stomodseum, or primitive
buccal cavity, as a tubular diverticulum (Rathke's), which eventually loses its
connection1 with the oral tissues to become included within the cranial cavity
and intimately attached to the neural bud. Both pre- and posthypophysis are
therefore of ectodermal origin and have developed from a conjunction of surface
tissues which have migrated from opposed (ventral and dorsal) parts through the
head! The prehypophysis is much the larger and somewhat embraces the post-
hypophysis; the two are inseparable, however, and together occupy the fossa
hypophyseos of the sphenoid.
The two parts of the hypophysis are as distinct in structure as they are in em-
bryonic origin. The posthypophysis consists of a mass of neuroglia, connective
tissue, and bloodvessels; the structure of the prehypophysis is distinctly glandu-
lar, resembling that of the parathyroid bodies. It is surmised that the latter is
the functional part of the hypophysis — concerned with the internal secretions,
and usually involved in the pathological form of giantism called acromegaly.
The Terma (lamina terminalis s. cinerea] (Fig. 592). — The terma is a thin, easily
torn lamina between the chiasm and the precommissure, limited laterally by the
closely approximated hemicerebra, and constituting the primitive, undifferentiated
cephalic boundary of the original neural tube.
The Optic Tract and its Central Connections. — In the section on the develop-
ment of the brain it was learned that the optic nerve is not a peripheral nerve ; it is
rather a central brain tract extruded from the neural tube. Evidence is at hand
that in ancestral vertebrates the general cutaneous sensor system was also capable
1 Occasionally the channel persists as the cranio-pharyngeal canal.
918
THE NERVE SYSTEM
of light perception. With the recession of the neural tube from the surface and
in company with the morphological differentiation of the head-end, a light-perceiv-
ing pair of organs arose as a special development. The distal end of the optic
brain-vesicle becomes the retina, in structure like the brain-wall, whose cell-
axones carry afferent impulses to the brain. Although the optic fibres enter the
ventral wall of the brain, the retina is originally derived from the dorso-lateral
(sensor) wall of the second neuromere (Fig. 558). The parietal organs, also
light-perceiving, likewise developed as paired dorsal buds farther caudad, eventu-
ally to atrophy, as the more frontal optic organs better subserved the purposes
of the organism.
The remarkable and as yet unexplained fact regarding the optic apparatus
is that the afferent fibres from the retinal cells pass into the ventral wall to cross
UNCROSSED FIBRES FROM LEFT HALF
OF LEFT RETINA TO LEFT CENTRES
CROSSED FIBRES FROM LEFT HALF
OF RIGHT RETINA TO LEFT CEN-
TRES
CONNECTING LEFT SIDE OF BRAIN I
WITH LEFT HALF OF RETINA AND 1.
CONSEQUENTLY RIGHT HALF OF
FIELD OF VISION
MACULA LUTEA
INTERNAL GENICULATE BODY
AND ITS NERVE CELLS
EXTERNAL GENICULATE BODY
AND ITS NERVE CELLS
OPTIC RADIATION
FIG. 594. — Diagram of the course of the optic fibres. (W. Keiller in Gerrish's Anatomy.)
to the opposite side, forming a decussation which is total, or nearly so, in vertebrates
below the mammals; the more laterally placed the eyes are the more nearly total
is the decussation.1
Although the optic vesicle is a diverticulum of the fore-brain in its cephalic
portion, the optic tract in its central connections becomes intimately related with
the pregeniculum and pulvinar, with the pregeminum of the mid-brain, and with
the occipital cortex of the cerebrum. Some of these central structures are way-
stations in reflex-paths; the occipital cortex alone is the actual visual centre,
though visual perceptions are here brought into association with tactile, auditory,
and other impulses.
1 Possibly the reflex contraction of the muscles on one side of the body in the ancestral vertebrate followed
the perception of a menacing object by the eye of the opposite side; hence the advantage of a decussation.
THE CEREBRAL HEMISPHERES 919
Chiasm. — From the retina of each eye the so-called optic nerves converge to par-
tially decussate at the base of the brain to form the chiasm, a white quadrangular
plate which presses in the primitive central gray floor of the third ventricle, as pre-
viously described. Approximately one-third of the fibres of each optic nerve do not
cross to the opposite side. The chiasm is further reenforced by the infracommis-
sure (of Gudden) and other lesser fibre-tracts (commissura superior [Meynerti] and
commissura ansata [Koliiker]). The fibres in the chiasm are so complexly inter-
woven that only through exhaustive experimental, developmental, and pathologic
studies has it been possible to understand its structure. Broadly stated, the
fibres from the medial (or nasal) halves of the retinae decussate in toto, while those
from the lateral (or temporal) halves do not cross. Leaving the chiasm, the
crossed medial and uncrossed lateral fibres form the slightly flattened optic tracts
coursing caudo-laterad, embracing the crura cerebri and dividing in the neighbor-
hood of the pregeniculum into two "roots," a mesal and a lateral root. The
mesal root is in reality not a part of the true optic path; it is a separate fascicular
representation of the infracommissure of Gudden, composed of fibres forming a
reciprocal bond of union (commissural) between the postgeniculums of the two
sides and coursing through the chiasm i^Fig. 594). The lateral root of the optic
tract is the true visual path, composed of (a) the uncrossed fibres from the lateral
half of the retina of the same side and (6) the crossed fibres from the mesal half of
the retina of the opposite side. The fibres of the lateral root are distributed to
the primary or lower optic centres as follows: (1) Most fibres end in the pregenicu-
lum; (2) a lesser number end in the pulvinar; (3) the remainder end in the nucleus
of the pregeminum.
The pregeniculum and pulvinar are ganglionic way-stations or internodes in
which visual impulses are reflected, in large part, to the visual cortex in the occip-
ital lobe; the pregeminum, on the other hand, plays no part in the conduction of
impulses perceived as light or color; it presides rather over the eye-muscle reflexes
to visual1 stimuli, and in its turn is under the dominion of the higher cortical
centre. Reflex impulses are sent to oblongatal and spinal centres along axones
entering into the formation of the medial longitudinal bundle. The axones of
corticifugal neurones proceed to the nucleus of the pregeminum along the optic
radiation.2
The connections of the pregeniculum and pulvinar with the higher cortical
centre of vision are established by neurones, the cells of wrhich lie in the two gan-
glia just mentioned, and whose axones stream in an arched, more or less compact
bundle in the white matter of the hemicerebrum toward the occipital cortex.
Another system of neurones, whose cells lie in the cortex, sends its axones in
the reverse direction (corticifugal) to the two lower centres. The cerebral tract
thus formed between primary and secondary (cortical) centres is called the optic
radiation, to be studied more fully in the sequel. The components of the optic
path are delineated schematically in Fig. 594.
The Cerebral Hemispheres.
External Morphology. — Of all the component parts of the brain, the cerebral
hemispheres form the largest part, and their preponderance and remarkable
specialization underlie the extraordinary manifestations of the intellect so highly
amplified in man.
The term cerebrum, often employed loosely as embracing several brain-parts,
1 And auditory stimuli as well (see p. 907).
2 Centrifugal fibres, ending in the retina and probably arising from cells in the pr
discovered in the optic tracts.
egeminum. have been
920
THE NERVE SYSTEM
is here intended to include the brain-mantle and the olfactory lobe — equivalent to
the telencephalon of His, with the exception of the pars optica hypothalami. As
already indicated in the section on brain-development, there has occurred, in the
evolutionary history of man's vertebrate ancestry, a progressive increase of the
secondary fore-brain, with concomitant reduction of the rhinencephalon, or smell-
brain — the most archaic portion because of the important relations of the smell-
sense to the life history of the earliest vertebrates.1
In a mesal view of a hemisected brain (Fig. 595) may be seen the various parts
of the brain-stem and the cerebellum overlapped by the preponderatingly greater
cerebrum. Among the many notable features exposed to view in this brain-
section are certain fibre-masses, commissures, extending across the meson, and
therefore divided by the knife in this preparation. Of the commissures pertaining
to the cerebrum one is conspicuous for its size and firm consistency. This great
DICOMMISSURE
CHOROID PLEXUS OF
HIRD VENTRICLE
TENIA THALAMI
HABENAL
COMMISSURE
POSTCOMMISSURE
ROSTRUM
COPULA
PRECOM-
MISSURE
TERMA
CHIASM
O
NERVE
HYPOPHYSIS
VEN
FIG. 595. — Mesal aspect of a brain sectioned in the median sagittal plane.
fore-brain commissure is the callosum already mentioned as being demonstrable
in the depths of the intercerebral cleft on divaricating the lips of this fissure. The
callosum constitutes a massive system of association fibres for the bilateral coordi-
nation of corresponding cortical parts. It is thickened caudally, forming the
splenium of the callosum ; f rontad it bends on itself ventro-caudad to form the germ
("knee"), including an interval, between the two limbs, which is flanked on both
sides by a thin lamina (hemiseptum) and bounded ventrad by the fornix, constitu-
ting a closed cavity, the pseudocele (or "fifth ventricle"). The recurved ventral
part of the genu tapers into a thinner, beak-shaped part, the rostrum. The rostrum
is joined to the terma, frontad of the precommissure, by a thin lamina, the copula
(lamina rostralis; lamina baseos alba).
1 For a more thorough discussion on the natural subdivision of the fore-brain, based upon comparative
morphology, see the paper by G. Elliott Smith, Journal of Anatomy and Physiology, 1901.
THE CEREBRAL HEMISPHERES
921
An arched structure composed of longitudinal fibre-bundles comes to view
ventrad of the junction of the splenium with the body of the callosum, proceeds
fronto-ventrad with its convexity frontad, to sink from view in the substance of
the hypothalamic gray at a point just caudad of the precommissure. This white
arched bundle is the fornix. Between it and the callosum, rostrum, and copula
stretches a thin, translucent lamina of nerve-tissue — the hemiseptum. The hemi-
septa of the two sides together have usually been termed the septum pellucidum,
while the enclosed narrow cavity is called the pseudocele or fifth ventricle. The
subjacent parts revealed in this section have already been described; the mor-
phology and internal relations of the callosum, fornix, and hemiseptum will be
described at a later stage.
OCCIPITAL
PO
INTCRCEREBRAL
ISSURE
FRONTAL INTERCEREBRAL
POLE FISSURE
FIG. 596. — The cerebral hemispheres viewed from above. (Spalteholz.)
The cerebral hemispheres together, as viewed from above or dorsally, appear
as two symmetrical masses in close apposition, conforming in outline to that of
the cranial cavity, which they so nearly fill. The frontal extremities or poles are
massive and rounded, preponderatingly so in comparison with the brains of any
related primate species. The occipital poles are each more pointed, but expand
frontad into the widest part of the cerebrum — the parietal lobes. The cerebral
hemispheres or, briefly, the hemicerebra are partially separated from each other
by the intercerebral cleft or fissure (fissura longitudinalis cerebri), into which fits
922
THE NERVE SYSTEM
a fold of the dura— the falx. By means of a large commissural band of white fibres
—the callosum — the cerebral halves are joined together in the depths of the inter-
cerebral cleft. All adjacent parts of the brain are overlapped by the ponderous
cerebrum so as to entirely conceal the thalamic portion and the mid-brain, while
the occipital lobes overlap the cerebellum with the intervening tentorium— another
fold of the dura. Further description will be restricted to each hemicerebrum.
Configuration of Each Hemicerebrum.— Each hemicerebrum presents an
outer convex surface (fades convexa cerebri), applied to the corresponding half of
the cranial vault; a mesal flattened surface (fades medialis cerebri), which lies in
a sagittal plane, applied to the corresponding surface of the opposite hemicerebrum,
with the intercerebral cleft intervening, and for the most part in contact with the
falx; and a basal or ventral surface, of irregular form, resting frontad upon the floors
of the anterior and middle cranial fossae, and caudad upon the tentorium.
OCCIPITAL F.
FIG. 597. — Principal fissures and lobes of the cerebrum viewed laterally.
Prominent in the lateral and ventral views is the blunt projection of the temporal
pole, while at the ventro-lateral border, nearer the occipital pole, is a slightly
marked indentation usually called the pre-occipital notch. The deep valleculai1
depression between the orbital surface and the temporal pole accommodates the
great wing of the sphenoid.
More or less distinct borders demarcate the surfaces. The arched dorsi-mesal
border intervenes between the mesal and the convex surfaces; a straight mesorbital
border intervenes between the orbital and mesal surfaces of the frontal lobe; a
ventro-lateral border separates the tentorial surface from the lateral, convex
surface of the occipital and temporal lobes ; while an obtuse border — the meso-
ventral or internal occipital border separates the tentorial from the mesal surfaces.
Cerebral Fissures and Gyres. — The surface of each hemicerebrum presents
alternating depressions or fissures which demarcate gyral elevations — the convolu-
tions or gyres.1 The fissures vary in depth from that of a mere shallow groove
to as much as 30 mm., and may attain a length of 15 cm. They are more or less
: Consistent with the use of the English lobe and lobes (for lobus and lobi), the English (lyre and gyres are
preferable to ayrus and gyri. The term fissure is here uniformly employed for all anfraetuosities of the sur-
face, though sulcus (pi. sulci) is quite as generally used; sometimes both terms are indiscriminately mixed.
THE CEREBRAL HEMISPHERES 923
sinuous and ramified. They mark the surface with fairly approximate uniformity,
that is, one rarely finds an unfissured surface more than 15 to 20 mm. in width.
Numerous functional and mechanical influences must be credited with bringing
about the complex foldings of the cerebral surface, principally (a) resistance of
the cranium to the expanding brain or "mechanical packing;" (6) differences of
growth-rate in different parts of the cortical surface; (c) differences of growth-
rate of different fibre-bundles retarding cortical expansion along the fissure-lines
and elongating to help in the formation of the gyres. The obvious result, whatever
the influences may be, is an expansion of the cerebral cortex to an enormous
degree, so that, instead of having a surface-area of only 60,000 sq. mm. (if un-
convoluted), the average adult cerebrum has a cortical area of 200,000 sq. mm.
or more. Furthermore, the vascular pia, closely investing the surface and dipping
into every fissure, is expanded in a like manner, affording an ample and uniform
supply of blood for the entire cerebral cortex.
The cerebral vesicle of the fcetal brain presents a smooth surface during the first
half of intrauterine life,1 except for the depressed fossa at the site of the future
insula — destined to become buried in the depths of the sylvian cleft formed by the
apposition of the more energetically growing contiguous parts of the cerebral
mantle. Some of the cerebral fissures develop early as infoldings of the com-
paratively thin wall of the vesicle, and hence produce corresponding projections
into the cerebral cavity; these are termed the total or complete fissures. The
remaining fissures are only linear depressions of the surface not involving the entire
thickness of the wall — the partial or incomplete fissures. The complete fissures and
their correlative projections into the cerebral cavity (lateral ventricle) are:
Fissure. Internal Eminence.
Hippocampal fissure. Hippocampus.
Calcarine fissure. Calcar.
Collateral fissure. Collateral eminence.
Occipital fissure. Occipital eminence.
Among the remaining cerebral fissures, of which over fifty have been recognized
and named, some are constant in representation in all normal brains, while others
are of variable occurrence in different individual specimens. The constant
fissures are those which regularly exist as interlobar and intergyral boundary
lines forming a common pattern for all normal brains, but these, like all cerebral
fissures, are subject to many individual variations as to course, depth, length,
mode of branching, and anastomosis with neighboring fissures or manner of
interruption by gyral isthmuses. The range of individual variations is so great
that no two brains can be said to be exactly alike ; in fact, one may find numberless
stages of complexity in the cerebral surface configuration from the simply fissured
brains of mentally inferior individuals and races to the complexly fissured and
more highly organized brains of vigorous thinkers and talented geniuses among
the highly intellectual races of man.
Cerebral Lobes and Fissures. — The cerebral surface is divided into five prin-
cipal areas called lobes, demarcated by certain constant fissures which are more
or less conspicuous, and were therefore selected by the older anatomists as arbi-
trary boundary lines; these are termed the interlobar fissures.
The lobes are: (1) the frontal; (2) the parietal; (3) the temporal; (4) the occipital;
(5) the insula. The inter-lobar fissures are : (1) the sylvian; (2) the central; (3) the
occipital; (4) the calcarine; (5) the circuminsular. A series of fissures demarcating
1 The so-called transitory fissures of older descriptions may be neglected, since the researches of Retzius,
Hochstetter, and Mall have shown these to be in reality artifacts due to postmortem swelling.
924
THE NERVE SYSTEM
the rhinencephalon from the pallium or cerebral mantle proper will be considered
at a later stage.
The Interlobar Fissures. The Sylvian Fissure and its Kami (fissura cerebri
lateralis [Sylvii]). — This fissure is a well-marked cleft on the base and side of the
hemicerebrum. Traced laterad from the region of the preperforatum, it begins
as a deep depression between the orbital surface of the frontal lobe and the tem-
poral pole, corresponding to the bony ridge formed by the lesser wing of the sphe-
noid and extending to the convex surface. This portion of the fissure is termed
the basisylvian fissure or vallecula sylvii, as far as the sylvian point.1 The sylvian
point marks the conjunction of the main portion of the sylvian fissure with its
basisylvian part as well as one or two rami. These rami are: (1) the presylvian
ramus; (2) the subsylvian ramus.
INTERCEREBRAL F.
F.=FISSURE
G.= GYRE
FIG. 598. — Cerebral fissures and gyres viewed dorsally.
The Presylvian Ramus2 usually proceeds dorsad, slightly inclined frontad, for
a distance of 2 to 3 cm. into the subfrontal gyre.
The Subsylvian Ramus (anterior horizontal limb] extends frontad for a distance
of 1.5 to 2. cm., parallel to the orbito-f rental (superciliary) margin.
These two rami often spring as shorter branches from a common stem and both
may be replaced by a single unbranched limb.
The sylvian fissure proper is the most conspicuous part. It extends from the
sylvian point in a caudal direction, inclined slightly dorsad,3 on the lateral surface
of the cerebrum for a distance averaging 6 cm. It separates the temporal lobe
1 So called in cranial topography.
2 Also called the anterior ascending limb. In B. N. A. terms the name for this fissural branch is Kamua
anterior asc.endens fissurie cerebri lateralis.
3 Its inclination to the horizontal plane is called the syh^n angle, approximately 15 degrees.
THE CEREBRAL HEMISPHERES
925
wholly from the frontal and partly from the parietal lobe. It usually ends in an
upturned manner, in the parietal lobe, the change of direction being oftener
abrupt than gradual; this terminal piece receives the name of episylvian ramus.
Occasionally a short ramus is sent ventrad into the supertemporal gyre and is
called the hyposylvian ramus.
The sylvian fissure ranges in depth from 15 mm. or less at the presylvian point
to 25 or 30 mm. at the postsylvian point, correlative with the contour of the insula,
which lies in its depths. If the lips of the sylvian fissure be divaricated the
insula is revealed as a cortical district, of tetrahedral form, which is normally
completely concealed by overlapping portions of the hemicerebrum called the
opercula. These are four in number: (1) the operculum proper, (2) the preoper-
culum, (3) the suboperculum, and (4) the postoperculum.
The operculum (frontoparietal operculum) is composed of the adjacent portions
of the ventral border of the frontal and parietal lobes, the sylvian fissure interven-
ing between it and the postoperculum, which is the overlapping part of the temporal
lobe. The pre-operculum is a small triangular portion embraced by the presylvian
INTERLOCKING
GYRES
PRECENTRAL
GYRE
POSTCENTRAL
GYRE
FIG. 599. — Central fissure fully opened up, so as to exhibit the interlocking gyres.
and subsylvian rami, and is also called the pars triangularis or Broca's cap. The
suboperculum (orbital operculum) is small, demarcated by the subsylvian ramus,
and for the most part on the orbital face of the frontal lobe, projecting slightly
over the frontal part of the insula, with its margin separated from the temporal
pole by the basisylvian cleft.
The overlapping opercula are demarcated from the insula by the circuminsular
fissure (sulcus circular is Reilii).
Development of the Insula and the Sylvian Cleft. — The insular cortical district
is topographically correlative with the great gray ganglia of the cerebral hemi-
sphere, particularly the lenticula, from whose ectal surface the insular cortex is
but little removed. As will be learned at a later stage, few if any projection fibres
pass to and from the insula ; its function is almost wholly associative for adjacent
parts of the cerebral mantle. The insula therefore becomes buried beneath the
more energetically growing and bulging parts immediately around it. There is at
first a slight fossa (observable in the tenth to twelfth week) which, as develop-
ment proceeds, and as the overhanging opercula encroach upon the insula, becomes
more deeply situated as a cleft-like depression until at birth the fossa has become
a fissure, with the insula perhaps slightly exposed near its cephalic extremity,
where the incomplete apposition of the opercula leaves a triangular space. This
926 THE NERVE SYSTEM
space is usually obliterated in childhood, but is commonly met with in certain
races (negro, Australian) and in brains showing developmental defects or arrest.
The mechanics of the formation of the surface outline of the sylvian fissure by
the apposition of the growing and plastic opercula may be understood by a refer-
ence to Fig. 604.
The Central Fissure (fissure of R,olando [sulcus centralis]). — The central fissure is
situated at about the middle of the convex surface, and, coursing obliquely latero-
frontad, divides this surface into approximately equal parts, intervening between the
frontal and parietal lobes. It may be traced from a point at or near the dorsi-mesal
border, about 1 cm. caudad of the mid-point of the occipito-f rontal arc. It then runs
sinuously latero-frontad to within a short distance of the sylvian fissure, about 2 cm.
caudad of the sylvian point; its line of general direction makes an angle of about
70 degrees with the median line (Rolandic angle). If measured along its sinuosities,
its length averages 10.5 cm. Its curved course may be analyzed into five alternate
curves (sometimes more or less), of which three are convex frontad and two caudad.
It is rarely very much branched and does not often anastomose with neighboring
fissures. Its dorsal end bears a constant relation to the caudal limb of the para-
central, frontad of which it can be found as a hook-like curve. If the lips of the
central fissure be divaricated, interdigitating sub-gyres are commonly seen in its
depths. These interlocking gyres are often fused to a greater or lesser degree,
and a total interruption of the fissure has, in rare instances, been observed. The
central fissure develops at about the end of the fifth month of intrauterine life, not
as a single integer, but as the result of the union of two segments: a short dorsal and
a longer ventral segment. As development proceeds these segments eventually
unite end to end, and at the site of this union a vadum (or shallow uprising of the
floor of the fissure) or even a complete isthmus may be demonstrated in the adult
brain. Only three cases of bilateral interruption are on record.
The Occipital Fissure (fissura occipitalis). — The occipital fissure is a deep
cleft across the dorsi-mesal border trans-secting the occipito-frontal arc at about
5 cm. from the occipital pole, and extending upon both the mesal and the convex
surfaces. On the meson it attains a length of 3 to 3.5 cm. (to its junction with the
calcarine fissure) while its lateral extent is shorter (2 to 2.5 cm.). It is quite
deep throughout and usually shows a number of interdigitating sub-gyres.
The Calcarine Fissure ( fissura calcarind). — The calcarine fissure is a slightly arched
fissure which is usually joined with the occipital fissure at the apex of the cuneus
and extends caudad to the occipital pole, ending in a bifurcation. The fissure is
composed of two integers which may be partially or completely separated (by a
vadum or an isthmus); the caudal segment may then be distinguished as the post-
calcarine fissure.
The occipital and calcarine fissures join to form a Y-shaped junction ; the two
limbs of the Y embrace the cuneus, while the stem is continued as the occipito-
calcarine stem for a distance of about 3 cm. This fissural stem is allotted to the
occipital fissure by some and to the calcarine fissure by other authors. As there
is no greater frequency of confluence with one as against the other, so far as present
statistics go, it is preferable to assign no special relationship for this stem to one
cr the other principal fissure.
I. Frontal Lobe. Fissures of the Frontal Lobe. 1. LATERAL SURFACE. —
The lateral surface is bounded by the dorsi-mesal arched border, by the fronto-
orbital (or superciliary) border, by the sylvian fissure (in part), and by the central
fissure. The principal fissures making this surface demarcate four gyres: (1) the
precentral, (2) superfrontal, (3) me dif rontal, and (4) subfrontal gyres. The fissures
are: (1) the precentral, (2) superfrontal, and (3) subfrontal fissures. In addition
must be described certain fissures which are intragyral and of more or less con-
stant occurrence.
THE CEREBRAL HEMISPHERES
927
The Precentral Fissural Complex (milcus prccentralis) . — Two fissural integers
which are sometimes joined extend more or less parallel with the central fissure.
The mesally situated piece is usually of zygal (yoke-shaped) shape or triradiate, and
usually anastomoses with the superfrontal fissure. From its position it is termed
the supercen|ral or superior precentral fissure (sulcus precentralis superior). The
laterally situated piece is of longer extent, sometimes straight or slightly sinuous,
sometimes arched like an inverted L, or T-shaped. It usually anastomoses with the
subfrontal fissure. The t\vo precentral segments demarcate the precentral gyre
from the remaining three gyres of the lateral surface of the frontal lobe.
The Superfrontal Fissure (sulcus frontalis superior) usually springs from the
supercentral and pursues a sinuous course frontad, to become lost, as a rule, in
the zigzag or transverse ramifications of the prefrontal region. It is usually quite
ramified and often anastomoses with other fissures. It demarcates the superfrontal
from the medifrontal gyre.
GYRE
•RAMUS
FIG. 600. — Fissures and gyres of the lateral surface of the left hemi cerebrum.
The Subfrontal Fissure (sulcus frontalis inferior) is most often confluent with the
precentral, less often with the supercentral fissure. It proceeds frontad in an arched
course, to end either in a bifurcation or by anastomosing with other fissures (radiate
fissures, orbito-frontal fissures, or medifrontal fissures). The subfrontal fissure
demarcates the medifrontal from the subfrontal gyre.
Both the superfrontal and medifrontal gyres are characterized by a more or
less pronounced longitudinal subdivision by less constant fissural segments. They
are: (1) the paramesal fissure (sulcus paramedialis) occupying an intermediate posi-
tion between the superfrontal fissure and the dorsi-mesal border, in the super-
frontal gyre, more often composed of a series of short segments which become lost in
the more complex configuration of the prefrontal region; (2) the medifrontal fissure
(sulcus frontalis medius) situated in the prefrontal part of the medifrontal gyre,
rarely extending throughout, and usually ending cephalad in a widely spread
bifurcation which constitutes the orbito-frontal fissure when independent. The
medifrontal fissure is usually very much ramified and frequently anastomoses
with neighboring fissures. The fissure is a characteristic of human and anthro-
poid brains only.
928
THE NERVE SYSTEM
By the occurrence of either or both paramesal and medifrontal fissures, the
ordinary three-tier type of frontal lobe is converted into a four-tier and five-tier
type; the latter more often in the brains of the more highly intellectual— a feature
which is concomitant with the comparatively late phyletic and embryonic develop-
ment of the two secondary fissures described.
Other, less important, fissures are: (1) the inflected fissure (fissura inflexa) , incis-
ing the dorsi-mesal border between the central fissure and the cephalic limb of the
paracentral; (2) the radiate fissure, near the lateral orbito-f rental border; (3) the
trans-precentral, a short oblique piece ventrad of the central and usually dipping into
the sylvian cleft, and (4) the diagonal fissure between the presylvian ramus and
the ventral end of the central, and often confluent with the precentral (Fig. 600)
2. MESAL SURFACE.— The mesal surface of the frontal surface lobe is bounded
by the dorsi-mesal border, the mesorbital border, and the callosal fissure. An
arcuate fissure or system of fissures intermediate between the dorsi-mesal margin
and the callosal fissure divides this surface into the superfrontal gyre, mesal
aspect, and the callosal gyre. The name " calloso-marginal" was usually applied
G. = GYRE
F.= FISSURE
FIG. 601. — Fissures and gyres of the mesal surface of the left hemicerebrum.
to this fissure, but an examination of many brains reveals a certain integrality
of fissural parts which are not always connected. One constant segment from
its relations with the central fissure is called the paracentral fissure, composed
of a main stem with a cephalic and a caudal limb, embracing the paracentral
gyre. Frontad thereof extends the supercallosal fissure, often in two segments,
running a concentric course between the arched dorsi-mesal border and the genii
of the callosum. The supercallosal may be confluent with the paracentral. The
supercallosal is, as a rule, quite ramified, its branches transcribing the super-
frontal gyre. In the prefrontal region and ventrad of the genu of the callosum
lie one or two fissures, more or less parallel to the mesorbital border, and called,
respectively, the rostral and subrostral fissures (sulci rostrales).
3. ORBITAL SURFACE. — The orbital surface of the frontal lobe is constantly
marked by a straight fissure, the olfactory fissure (sulci olfactorius) , which runs
parallel to the mesorbital border and is occupied by the olfactory bulb and tract.
It is about 5 cm. in length and demarcates the mesorbital gyre from the remaining
orbital gyres. This orbital surface is marked by a fissural system (sulci orbitales)
THE CEREBRAL HEMISPHERES
929
that is usually of zygal type, H-shaped or K-shaped, quadriradiate, or, rarely,
triradiate. When the transverse element is sufficiently pronounced it merits
the name of transorbital fissure, demarcating the preorbital from the postorbital
gyral field.
Gyres of the Frontal Lobe (lobus frontalis}. 1. LATERAL SURFACE. — The pre-
central gyre (gyrus centralis anterior] , one of the chief motor areas of the cerebral
cortex, is a moderately sinuous gyre extending from the dorsi-mesal border to
the sylvian fissure and demarcated by the central and the precentral fissures
(supercentral + precentral).
The superfrontal gyre is limited laterally by the superfrontal fissure, while it
is continuous over the dorsi-mesal border with its mesal surface.1 It merges
insensibly with the medifrontal gyre in the prefrontal region, while it may be
partially subdivided by the paramesal fissure.
INTERCEREBRAL F.
R= FISSURE '
G. = GYRE
FIG. 602. — Fissures and gyres of the basal surface of the cerebrum.
The medifrontal gyre (gyrus frontalis medius) is broader than the preceding,
demarcated by the superfrontal and subf rental fissures, and often marked by the
medifrontal fissure in its prefrontal portion.
The subfrontal gyre (gyrus frontalis inferior] is limited by the subfrontal fissure
and the basisylvian + sylvian proper. It is traversed by the presylvian and sub-
sylvian rami, embracing the pre-operculum or pars trianglaris. The gyre is of
historic importance since Broca, in 1861, declared it to be the seat of speech con-
trol. (See Cerebral Localization.)
1 There being no fissure at this border, it is improper to give the mesal surface of this gyre a different name
(i. e., " marginal gyrus" of the authors).
59
930 THE NERVE SYSTEM
2. MESAL SURFACE. — On the mesal surface of the frontal lobe and embracing
the dorsal end of the central fissure lies an oval lobule or gyre called the par;:
central gyre (lobulus paracentralis) , limited by the paracentral fissure with its
caudal and cephalic limbs. Frontad thereof extends the large arched mesal
surface of the superfrontal gyre (gyrus frontalis superior), limited by the super-
callosal fissure. Between the latter fissure and the callosal fissure, concentrically
situated with respect to the superfrontal, lies the callosal gyre (the "gyrus form-
catus" of the authors).
Frontad these two gyres arch around the genu of the callosum, to become merged
through the disappearance of the intervening supercallosal fissure, and the rostral
fissures alone mark this surface.
3. ORBITAL SURFACE. — The olfactory fissure and the mesorbital border bound
the mesorbital gyre (gyrus rectus}. The remaining orbital surface is not regularly
divisible on account of the great variability of the orbital fissures; when the
transorbital fissure is pronounced, a pre- and postorbital gyre may be distin-
guished.
The postorbital limbus is a formation occasionally met with on the orbital sur-
face. It consists of a curved, welt-shaped eminence demarcated by an incisure
created by the lesser wing of the sphenoid, and due, apparently, to the intrusion
of the postorbital portion into the middle fossa.
II. Parietal Lobe (lobus parietalis). Fissures of the Parietal Lobe. 1. LATERAL
SURFACE. — The lateral surface is bounded by the dorsi-mesal border, by the central
fissure, and by a part of the sylvian fissure; it is only partially demarcated from
the occipital lobe by the occipital fissure, and merges gradually into the temporal
lobe.
The principal fissures marking its surface consist of a group of integral segments
showing various degrees of confluence in different individuals and formerly
known in the aggregate as the intraparietal sulcus of Turner (sulcus intraparietalis).
Two of the fissural segments present much the same parallelism to the central
fissure which was noted for the precentral group, and hence these are termed
the postcentral fissural complex.
The postcentral fissural complex (sulcus postcentralis) comprises a longer mesal
and a shorter lateral (and ventral) segment, which are confluent in about 75 per
cent, of brains and then very much resemble in length, continuity, and course
the central fissure. This appearance has given rise to reports of alleged duplica-
tion of the central; an analysis of the relations of the dorsal ends of the fissures
in question with the caudal limb of the paracentral removes all doubt.
The postcentral fissure (proper) is the longer mesal (and dorsal) segment. Its
dorsal end is frequently bifurcated and sometimes embraces the dorsal extension
of the caudal limb of the paracentral. The subcentral fissure constitutes the shorter
latero-ventral segment.
The parietal fissure is usually a slightly arched fissure inclining meso-caudad,
sometimes independent but more often confluent, with one or both of the post-
central segments just described. It demarcates the parietal gyre from the sub-
parietal district.
The paroccipital fissure, in whole or in part, probably represents a part of the
simian exoccipital or " Affenspalte," isolated by the upgrowth of gyral protons
which are totally submerged in the ape brain, but rose to the surface concomitant
with the rise in functional dignity of cortical areas so important in the human
brain. The fissure is almost invariably of zygal shape, its stem directed sagittally,
its ends bifurcated. Its confluence with the parietal fissure seems to be subject to
some morphologic law; continuity is the rule on the left side (77 per cent.), and
occurs less often on the right. The combination of continuity on the right and
separation on the left is a rare one (6 per cent.).
THE CEREBRAL HEMISPHERES 931
Less constant fissures are the transparietal, in the parietal lobe and the inter-
medial (Fig. 600). In the subparietal district terminate the upturned ends of
the sylvian (i. e., episylvian ramus] of the supertemporal and the meditemporal
fissures.
2. MESAL SURFACE. — The mesal surface of the parietal lobe is equivalent to
the quadrangular precuneus, limited by the paracentral and occipital fissures,
while ventrad it is imperfectly separated from the callosal gyre by the precuneal
fissure (posilimbic sulcus), usually of zygal or triradiate form and occasionally
confluent with the paracentral.
Gyres of the Parietal Lobe. 1. LATERAL SURFACE. — The postcentral gyre (gyms
centralis posterior) is one of the chief somsesthetic areas of the cortex. It is a long,
more or less sinuous convolution extending obliquely from the dorsi-mesal border
to the sylvian fissure and demarcated by the central and the postcentral + sub-
central fissures.
The parietal gyre (gyrus parietalis) lies between the dorsi-mesal border and the
parietal fissure, bounded cephalad by the postcentral, caudad partly by the
occipital fissure, the transition to occipital lobe being maintained by the arched
paroccipital gyre.
The subparietal district or lobule (lobulus parietalis inferior] is divided into
three convolutions which arch around the upturned ends of the sylvian, super-
temporal, and meditemporal, and merge insensibly with the adjacent temporo-
occipital gyres. The marginal (supramarginal) gyre arches over the extremity of
the episylvian ramus and is connected frontad with the postcentral gyre, ventrad
with the supertemporal gyre. The angular gyre (gyrus angularis) arches over the
upturned extremity of the supertemporal fissure, and its limbs fuse with the super-
temporal and meditemporal gyres. The postparietal gyre is not always clearly
defined ; it arches around the upturned end of the meditemporal or its representa-
tive segment; mesally it is bounded by the paroccipital fissure. Variable inter-
medial fissures sometimes help to define the angular gyre from its two neighbors.
2. MESAL SURFACE. — The mesal surface of the parietal lobe has already
been described as equivalent to the precuneus, from its position in "front" of the
cuneus or quadrate lobe from its general shape. It is sometimes marked by a
mesal extension of the transparietal fissure or by intraprecuneal fissures.
III. Occipital Lobe (lobusoccipitalis). Fissures of the Occipital Lobe. 1. LAT-
ERAL SURFACE. — The lateral surface of the occipital lobe is imperfectly demarcated
from the adjacent parietal and temporal lobes in most brains. The sharply defined
exoccipital fissure or " Affenspalte" of other primates has, in the ancestry of man,
been reduced to a series of fissural segments by the upgrowth of submerged cortical
parts. The paroccipital fissure, we have already learned, probably represents
one of the gaps in the series; another may be the sulcus lunatus (Elliott Smith),
usually termed the lateral occipital by the authors; lastly, a fissure sometimes called
the inferior occipital (suboccipital), and usually embraced, on the occipital pole,
by the bifurcate limbs of the postcalcarine, may complete the series. Further
researches are necessary to elucidate the morphology of this region.
2. MESAL SURFACE. — The mesal surface is equivalent to the wedge-shaped
region embraced by the occipital and calcarine fissures, and called the cuneus.
A fairly constant cuneal fissure traverses its surface parallel to the calcarine.
If it is ever determined that the morphological boundary of the occipital lobe is
as outlined above, the lobe is practically excluded from the basal surface of the
hemicerebrum.
IV. Temporal Lobe (lobus temporalis). Fissures of the Temporal Lobe. 1.
LATERAL SURFACE. — The lateral surface of the temporal lobe is bounded by the
basisylvian and sylvian fissures and by the ventro-lateral border; caudally it
merges into the adjacent parietal and occipital lobes.
932 THE NERVE SYSTEM
The supertemporal fissure (sulcus temporalis superior) is a deep, long (10 to 12
cm.), and usually continuous fissure which begins near the temporal pole, proceeds
ventrad of but parallel with the sylvian, to become upturned in the parietal lobe
and embraced by the arched angular gyre.
The meditemporal fissure (sulcus temporalis medius) is rarely continuous; more
often it is represented by a series of segments, two, three, or four in number, the
caudal segment running more vertically into the parietal lobe to be embraced by
the postparietal gyre. The meditemporal fissural segments run nearly parallel
with the supertemporal and demarcate the meditemporal from the subtemporal gyre.
2. TENTORIAL OR VENTRAL SURFACE. — Close to the ventro-lateral margin and
more or less parallel with it runs the subtemporal fissure (sulcus temporalis inferior],
extending from near the temporal to near the occipital pole. It is rarely continuous,
being usually broken up into two or more segments. It demarcates the subtem-
poral from the subcollateral gyre.
The collateral fissure (fissura collateralis) is a well-marked long (8 to 12 cm.) and
deep fissure extending from near the occipital to near the temporal pole. Caudally
it demarcates the subcalcarine gyre from the subcollateral; frontad it intervenes
between the latter gyre and the hippocampal gyre. Its middle part is correlative
with the collateral eminence. On the ventro-mesal aspect of the temporal lobe
and near its pole, cephalad of the uncus is a moderately marked fissure or groove
called, because of its topographic relation to the amygdala — a gray, ganglionic mass
— the amygdaline fissure (fissura ectorhinalis s. postrhinalis) or incisura temporalis.
OLFACTORY
CEREBELLUM.— liMiaiBiiP " <, LOBE.
FIG. 604.- — Cerebrum of an eight-months' human
FIG. 603. — Brain of a six-months' human embryo, embryo, left side. The insula is nearly covered in.
natural size, right side. (Kolliker.) (Testut.)
3. DORSAL OR OPERCULAR SURFACE. — The dorsal or opercular surface of the
temporal lobe enters into the formation of the sylvian cleft. It is but slightly
marked by a few oblique or transverse furrows (transtemporal fissures) demar-
cating slightly elevated transtemporal gyres.
Gyres of the Temporal Lobe. — The five principal fissures named subdivide the
lobe into five gyres. On the lateral surface lie the supertemporal, meditemporal,
and subtemporal gyres (gg. temporalis superior, medius et inferior) ; on the ten-
torial surface are the subcalcarine (gyrus lingualis), subcollateral (gyrus fusiformis;
g. occipitotemporalis) and part of the subtemporal.
The hippocampal gyre (gyrus hippocampi), formerly included in the "limbic
lobe," but morphologically belonging to the neopallium, occupies the dorsi-mesal
part of the ventral surface of the temporal lobe. The longer or shorter extension
of the occipito-calcarine stem partially (forming the isthmus gyri hippocampi)
interrupts its continuity with the callosal gyre. It is demarcated by the collateral
fissure (in part) and the hippocampal fissure, broadens out toward the temporal
pole, and appears to become bent upon itself dorsally to form the uncinate gyre
(uncus). As will be learned in the sequel, the hippocampal gyre is demarcated
THE CEREBRAL HEMISPHERIC
933
from the uncus proper by the intervention of the frenulum Giacomini — an exten-
sion of the narrow, gray, dentate gyre.
Near the temporal pole it is demarcated from the subcollateral gyre by the
fissura rhinica,1 or postrhinal fissure; this fissure is not infrequently confluent with
the collateral. .
The surface of the hippocampal gyre, particularly in the zone along the hippo-
campal fissure, is of a more whitish color than is characteristic of other cerebral
gyres; this is due to a white reticular stratum of fibres, the substantia reticularis alba
(Arnold). The convex, broader part of the gyre is marked by numerous small,
wart-like eminences, resembling the skin of an amphibian, and called by Retzius
the verrucas gyri hippocampi. Just ventrad of the uncinate portion, or the ter-
minus of the hippocampal fissure, lies a groove marking the impression of the
free edge of the tentorium.
Fio. 605. — The left insula schematically represented in a supposedly transparent hemi cerebrum, showing how
it is concealed from view by the opercula.
The Insula (Central Lobe or Island of Reil) (Figs. 603, 604, 605).— The insula
lies deeply in the sylvian cleft and can only be seen when the lips of that cleft are
widely separated, since it is overlapped by .the opercula already described. With
the opercula removed, the insula presents a tetrahedral shape with its apex or
pole directed ventro-cephalad. Its borders are sharply outlined by the circum-
insular fissure except in the depths of the basisylvian cleft, where the insular cortex
is continuous with the gray substance of the preperforatum — the threshold or limen
insulae (belonging to the rhinencephalon). An oblique transinsular or central insular
fissure divides this district into a larger preinsula and a smaller postinsula. The
postinsula is usually a single long gyre (gyrus longus insulae), while the preinsula
is subdivided by shallow fissures into three, four, or five shorter preinsular gyres
built upon a radiate plan, converging in the region of the insular pole. As already
hinted, the insula represents an area of the brain-mantle whose growth did not
1 Called by Wilder, on account of its correlation with the amygdala, the amyadaline fissure.
palls it (in part) the incisura temporalis.
Schwalbe
934 THE NERVE SYSTEM
keep pace with that of the surrounding parts; hence its submergence by them.
The close apposition of the insular region to the subjacent basal ganglia, and the
failure of development of great masses of projection fibres so prominent elsewhere,
were doubtlessly factors therein. The insular cortex is uninterruptedly continuous
with the rest of the cortex, but it has become specialized into the purest association
centre in the cerebrum, and we shall learn of its intimate relations to the faculty
of speech at a later stage.
The Rhinencephalon or Olfactory Lobe (lobus olfactorius} (Figs. 606, 607,
609). — The grouping of the parts constituting the central olfactory structures
under the term "rhinencephalon" as distinguished from the rest of the fore-
brain (pallium) was first clearly made by Turner and proved by His to be
embryologically well founded and by Edinger to agree with phylogenetic develop-
ment. More light has been thrown upon the subject recently by Retzius and
Elliott Smith. The sense of smell, while highly useful in the quest for food in
earlier and lower forms of vertebrates, is relatively little used in the mental life
of man. The enormous preponderance of the cerebral mantle and the concomi-
tant atrophy of the rhinencephalon in the human brain afford one of the most
striking contrasts in brain morphology. This relatively feeble development in
bulk of the olfactory apparatus in the human brain by no means renders its
description simple. In fact, not until its development in lower macrosmatic animals
was studied could anatomists form even an approximately clear conception of the
seemingly disjointed remnants in the human brain of an olfactory apparatus so
relatively huge in lower animals. The great expansion of the cerebral hemispheres
and of the great commissure which connects them (the callosum) has been an
important factor in widely displacing primitively connected parts. The devel-
opmental history must be sought for in the writings of Edinger, Retzius, and
Elliott Smith.
The Rhinencephalon comprises:
1. Peripheral parts
2. Central or Cortical parts.
A comprehensive term for the peripheral part is lobus olfactcrius, divisible into
pre- and postolfactory parts.
1. Bulbus olfactorius.
2. Tractus olfactorius.
3. Tuberculum olfactorium and trigonum.
Preolfactory lobe ^ 4. Area parolfactoria (Broca).
I 5. Stria (gurus) olfactorius medialis.
6. Stria (gyrus) olfactorius intermedialis.
[^7. Stria (gyrus) olfactorius lateralis.
,t , , f 8. Preperforatum.
01>y [ e\ 9. Gyrus sulcallosus and Broca' s diagonal band.
The Preolfactory Division. — :The olfactory bulb and tract form a long and
slender band with a bulbous extremity situated on the basal aspect of the frontal
lobe and constituting a rudimentary remnant of a relatively large diverticulum,
developed from the sensor ectoderm close to the border of the neural plate before
it becomes converted into the neural tube and situated on either side of the neu-
ropore at the extreme frontal end. Although hollow at first, the cavity (rhinocele)
soon becomes obliterated.
The olfactory bulb (bidbus olfactorius) is an oval mass of reddish-gray color,
which rests on the cribriform plate of the ethmoid and is received in the olfac-
tory fissure on the orbital surface of the frontal lobe. It receives the numerous
olfactory nerves (fila olfactoria) from the nasal mucous membrane. The olfactory
THE CEREBRAL HEMISPHERES
935
tract (tractus olfactorius] is a bum! of white substance, of prismatic outline on
section, its apical ridge fitting into the olfactory fissure. Toward its root-region it is
somewhat narrowed.
The medial and lateral olfactory gyres are also termed the medial and lateral
roots of the tract, and diverge in the region of the trigonum. The olfactory
tubercle (tuberculum olf actor ium) is best seen if the bulb and tract be lifted
away from the olfactory fissure; the tubercle appears as a small pyramidal
elevation, its apex buried in the olfactory fissure, its irregularly triangular base
forming the trigonum olfactorium, a small gray area frontad of the preperforatum.
This area is marked by ridge-like elevations which appear like radiating roots of
the tract, and named, according to their position, the medial, intermediate, and.
lateral roots, striae or gyres. The lateral olfactory stria or gyre is continuous with
the limen insulse in the depths of the basisylvian cleft, and thence passes to the
BULB
TRACT
TRICONE
G. OLFACTORIO-
ORBITALIS
LATERAL STRIA
ANGULUS LATCRALIS
INTERMEDIATE STRIA
PREPERFORATUM
GVRUS AMBIENS
GYRUS SCMILUNARIS
FRCNULUM GIACOMINI
uncut
CYRUS SUBCALLOSUS
AREA PAROLFACTORIA
GYRUS OLFACTORIUS
MEDIALIS
LIMEN INSURE
BROCA'S DIAGONAL
BAND
SULCUS SEMI-
ANNULARIS
FIG. 606. — Schematic representation of the rhinencephalon, basal aspect.
uncus to end in the gyms ambiens and gyrus semilunaris. The sharp turn made
at the limen insulae is called the angulus lateralis. The medial olfactory stria or
gyre, a narrow gyral band, proceeds mesad and merges with the adjacent cerebral
surface; its extension on the mesal surface is known as the parolfactory area
(Broca) limited frontad by the anterior parolfactory sulcus (sulcus parolfactorius
anterior} and separated from the subcallosal gyre by the posterior parolfactory
sulcus (sulcus parolfactorius posterior).
The intermediate stria is not always very distinct ; when present it may be traced
from the proximal end of the olfactory tract for a short distance over the gray
field of the trigonum, to plunge into the gray of the preperforatum.
Postolfactory Division. — The preperforatum (anterior perforated substance]
occupies an irregular quadrate field between the olfactory trigone and the optic
chiasm and tract. A more or less marked groove (sulcus parolfactorius posterior},
which is identical with the fissura prima (His) of the embryo, separates the tri-
gonum from the preperforatum. Its frontal part, much perforated, is of a darker
936
THE NERVE SYSTEM
color than the hind portion; the latter is distinguished by the name of Broca's
diagonal band. This courses obliquely laterad along the optic tract toward the
uncus; mesally the bands of the two sides converge, frontad of the terma, and
proceed toward the rostrum of the callosum as narrow fields which taper to curve
ajound the genu and continue in the indusium of the callosum as the striae longi-
tudinales. The narrow field seen on the mesal aspect frontad of the terma and
precommissure is known as the gyrus subcallosus (formerly peduncle of the corpus
callosum). The continuity of the various parts may be understood by reference
to Figs. 606, 607, and 609.
INDUSIUM AND STRI/E
FUSION OF FASCIOLA
AND DENTATE GYRE
GYRI ANDRE/
RETZII
DENTATE GYRE
HIPPOCAMPAL FISSURE
•UNCUS
FRENULUM GIACOMINI
I GYRUS SEMILUNARI8
GYRUS AMBIENS
FIG. 607. — Schematic representation of the rhinencephalon, mesal aspect.
The cortical and central parts of the rhinencephalon comprise;
C 1. The hippocampus.1
2. The uncus.
3. Gyrus dentatus.
Cortical \ 4. Fasciola.
5. Indusium, medial and lateral longitudinal striae upon the callosum.
6. Gyri Andrese Retzii.
7. Gyri subcallosi.
8. Fornix and fimbria.
9. Albicans and albicantio-thalamic tract.
10. Part of precommissure.
.11. Part of hemiseptums.
Central or Cortical Parts of the Rhinencephalon. — Following the suggestion made
by Broca in 1878, it has been customary to designate these various parts by the
comprehensive term: limbic lobe. Broca's notion of the limbic lobe in man
was founded upon attempts to homologize the human cerebral configurations
with those found in lower animals. More recent researches have proved that
Broca's "limbic lobe" included parts belonging to the neopallium and not to the
rhinencephalon. The term is therefore inappropriate in a morphologic sense.
The hippocampus is the submerged, peculiarly folded margin of the cerebral
Central \
I
1 Not to be confounded with the hippocampal (tyre of the pallium.
THE CEREBRAL HEMISPHERES
937
hemisphere produced by the hippocampal fissure. Its architecture can best
be understood by referring to a frontal section (Fig. 608). It is seen that the
whole cerebral marginal wall is pushed into the ventricular cavity (medicornu)
as a fold caused by the intrusion of the hippocampal fissure. A secondary fold —
not produced by a fissure, however — constitutes the gyms dentatus. Super-
imposed lies a prominent white band — the fimbria — composed of axones from
the hippocampal cells, assisting in the formation of a white lamina, subjacent
to the endyma of the ventricle, and called the alveus. The whole formation
is characteristic of this region and from its fancied resemblance to a ram's horn —
a symbol used on the temple of Jupiter Ammon — the name of cornu ammonis1
FIG. 608. — Trans-section of the hippocampal gyrus. (Edinger.)
has been given; the name hippocampus was applied because of a fancied re-
semblance to the marine animal of the same name. The ventricular relations
and internal structure of the hippocampus will be given farther on (p. 947).
The uncus, with the atrophied lateral olfactory stria, is all that remains in the
human brain of the relatively large pyriform lobe of lower forms. It appears
to be a hook-like retroflexion of the hippocampal gyre which is partially encircled
by the gyrus dentatus. Morphologically speaking, it is only the apical portion,
or that which lies caudad of the dentate gyre which is the true uncus (the gyrus
intralimbicus of Retzius); the remainder is neopallial and a part of the hippo-
campal gyre. The uncinate or intralimbic gyre may be traced caudad in the
depths of the fimbrio-dentate fissure, along the dentate gyre, the dentato-fascicolar
i Frequently, but incorrectly, given as Amman's Horn.
938 THE NERVE SYSTEM
groove intervening, to be continued as the fasciola (gyrus fasciolaris of Retzius)
over the splenium of the callosum.
If the hippocampal gyre be depressed for the purpose of examining the depths
of the hippocampal fissure, there is revealed a narrow, gray band whose surface
is scored by numerous incisures and whose edge is notched at frequent intervals.
This corrugated band is the dentate gyre or fascia dentata. Partly overlapping it,
but farther laterad, lies a white band — the fimbria — extending caudad from the
uncus to become continued as the fornix.
The dentate gyre is demarcated from the hippocampal gyre by the hippocampal
fissure, from the fimbria by the fimbriodentate fissure, in whose depths lies the
narrow continuation of the uncus or gyrus intralimbicus — the fasciola. Extending
caudad, and for the most part parallel -with the fimbria, it loses its corrugated
appearance on approaching the splenium, then fuses with the fasciola, parting
company with the fimbria (which now becomes fornix), to be continued upon the
callosum as a thin, broad plate of gray matter — the indusium or gyrus epicallosus.
At the uncus the dentate gyre makes an abrupt turn to appear upon the mesal
surface, out of the depths of the hippocampal fissure, and encircles the neck of
the uncus, forming the frenulum Giacomini. Beyond this point it can be traced,
in rare instances, to the gyrus semilunaris.
The gyri Andre se Retzii are rudimentary gyral formations consisting of small,
rounded, oval or spirally corrugated eminences situated ventrad of the splenium
in the angular interval between the dentate and the hippocampal gyres. Struc-
turally they have been shown to belong to the hippocampal formation.
The indusium (gyrus epicallosus s. supracallosus}, considered to be a vestige
of the hippocampus, is a thin strip of gray substance superimposed upon the callosum
and raised into two paired ridges by longitudinal fibre-bundles which constitute
the mesal and lateral longitudinal striae.1 The indusium and its striae are continued
cephalad into the gyrus subcallosus; perhaps, also, into the parolfactory area
(Fig. 607).
The central connections of the rhinencephalon will be considered in the de-
scription of the internal configuration of the hemisphere. (See Fornix, Precom-
missure, etc.)
Internal Configuration. — Each hemicerebrum contains a cavity, the lateral
ventricle or paracele, an extension of the primitive neural cavity carried outward,
its contours modified by the developmental changes in the growth-history of the
secondary fore-brain vesicle. This central cavity is surrounded by the thick,
convoluted walls of nerve-tissue which make up the bulky cerebral hemi-
spheres. The cerebral tissue, as elsewhere in the central axis, is made up of gray
and white substance. ' Two well-marked types of gray substance are recognizable:
(a) the cortical, so named because its situation upon an interior white centre,
invites comparison with the rind (cortex) of a fruit; (6) the massive ganglionic
or nugget-like masses not dissimilar from the thalamus already described,
comprising, in this division of the brain, the caudatum, lenticula, and amygdala.
The white substance fills out the entire space intervening between the cortex,
the cavity of the lateral ventricle and the great basal ganglia, and is composed
of myelinic axones which connect the elements of the cortex with other parts of
the nerve system, or with other regions of the cortex of the same or the oppo-
site hemicerebrum.
If a brain, resting upon its basal surface, be sliced by successive horizontal
sections from above, the peripheral gray and internal white are brought into view.
The more superficial sections reveal relatively more gray than white substance;
deeper sections show a reverse condition and a section immediately dorsad of the
1 The mesal striae are also called Striae Lancisii; the lateral strias, Teniae tecti.
THE CEREBRAL HEMISPHERES
939
callosum reveals, in each hemicerebrum, a very extensive semioval field of white
substance, the centrum semiovale, surrounded on all sides by a narrow, convoluted
margin of gray substance, the cortex. A close examination of the cut surface, in a
fresh and normal brain, shows it to be studded with numerous minute red dots
(pumta vasculosa) produced by the escape of blood from divided blood-vessels.
The Cortex. — The cortex, as revealed in such a section, is not of uniform thickness
throughout; different regions show different cortical thicknesses. In general, the
cortex is somewhat thicker at the summit of a gyre than in the depths of an ad-
joining fissure, and it is thicker upon the convex than upon the mesal or basal sur-
faces. The maximum thickness is observed in the cortex of the central gyres and
the insula ; the minimum at the frontal and occipital poles, notably the latter. Not
only is the cortex not of uniform thickness, but it is not of homogeneous structure
as seen with the naked eye. An alternation of gray and white stripes is discernible,
particularly in the occipital cortex, where a white band runs parallel with the corti-
cal surface between two gray strata; this white stripe, first described by Gennari
and usually bearing his name, is also called the band of Vicq d'Azyr.
GYRUS
SEMILUNARIS
FRENULUM
GIACOMINI
FIG. 609. — Mesal view of a partly dissected hemicerebrum, to show the relations of fimbria, fasciola,
dentate gyre, and uncus.
The preponderance of white substance over gray substance in the cerebrum is a human charac-
teristic concomitant with the relative increase of the association cortex, in turn demanding a more
intricate interconnection of the many nerve-cells by a multitude of association neurones. These
coordinating fibre-systems are as truly representative of the complexity of man's thought appa-
ratus as the number of interconnecting wires within a telephone "central" station is indica-
tive of the amplitude of connections possible in that system. The proportions of gray and
white substance are expressed in the following tabulation:
Gray substance {£ortef. ' - : 33 per cent.
I Ganglia 6 per cent.
White substance 61 per cent.
The removal, by successive slices, of the dorsal parts of the cerebrum soon
brings into view the large expanse of transverse myelinic fibres, the callosum,
which connects the two hemispheres.
The Callosum (corpus callosum; trabs cerebri; commissura maxima}. — The
callosum is a thick stratum of transversely directed nerve-fibres, by which
940
THE NERVE SYSTEM
almost every part of one hemicerebrum is connected with the corresponding part
of the other hemicerebrum (Figs. 610 and 611). The axones composing it arise
from the small pyramidal or the polymorphous cells of the cerebral cortex, or
they may be collaterals from the long association or even the projection neurones.
They pass in both directions and within the centrum semiovale radiate in various
directions (radiatio callosi) between the fibres of the corona radiata to terminate in
the layer of small pyramidal cells of the cortex, thus forming a great transverse
commissural system, and at the same time roofing in the greater part of the lateral
ventricle in each half. A portion of the dorsal surface is free for a width of
about 1 cm. on either side of the mesal plane, partly covered by the indusium and
overlapped by the callosal gyres of the two sides, a fold of pia intervening.
The radiating mass of fibres may, for convenience of description, be sub-
divided into a pars frontalis, a pars parietalis, and a pars occipitotemporalis. The
frontal and occipito-temporal portions are compressed or thickened mesally
because the fibres cannot pass directly across, but curve, respectively, frontad
and caudad in each hemicerebrum to form two tong-like bundles, the preforceps
(forceps anterior s. minor) and postf creeps (forceps posterior s. major). The pars
parietalis constitutes the greater part of the "body" of the callosum. The fibres
FIG. 610. — Diagram of coronal section of cerebrum
to show course of fibres of callosum. (Testut.)
FIG. 611. — Diagram of horizontal section of cerebrum
to show course of fibres of callosum. (Testut.)
traversing the body (truncus corporis callosi) and the adjacent part of the
splenium curve round the postcornu and trigonum ventriculi of the lateral
ventricle, to form a thin but definite white stratum, the tapetum, in the roof
and ectal wall of these parts of the cavity.
The transverse direction of the fibres is rendered apparent in a dorsal view
of the exposed callosum in the form of the striae transversae. These are but little
obscured by a thin, gray lamina — the indusium — which is thickened longitudinally
by two symmetrically situated fibre-strands, the mesal (striae lancisii) and lateral
longitudinal striae (teniae tectae), already mentioned as rudiments of the rhinen-
cephalon.
The best conception of the size and form of the callosum is obtained from a
view of a mesal section. It is then seen to be a long, thick, somewhat flattened
arch which bends sharply upon itself frontad to form the genu (genu corporis
callosi) while its caudal end is rounded and somewhat folded closely upon itself
to form the splenium. The callosum ranges in length from 7 to 10 cm., its cross-
section area from 5 to 10 sq. cm., being longer and larger in heavier brains and
in those of the highly intellectual as compared with smaller and less highly efficient
brains. It extends to within 4 cm. of the frontal pole and to within 6 cm. of
the occipital pole. The thickness of the "body" averages 5 mm., of the splenium
THE CEREBRAL HEMISPHERES
941
9 mm. or more, while the maximum thickness of the genu is about 13 to 15 mm.
The reflected portion or rostrum (rostrum corporis callosi) gradually tapers into
a very thin lamina, the copula (lamina baseos alba), which in turn joins the terma
frontad of the precommissure.
The splenium (splenium corporis callosi) projects as a rounded welt over the
mid-brain, but is separated from it by a pial fold — the velum interpositum.
Further frontad the fornix becomes fused to the ventral surface of the callosum
for a short distance, to again leave it in its more arched course toward the albicans.
Two thin laminae, one on either side of the median plane, but closely applied to
each other and frequently partially fused, occupy the interval between callosum
and the fornix of each side. The laminae together are termed the septum lucidum
of the authors, each one being called a hemiseptum; the enclosed cavity is called
the pseudocele or fifth ventricle, though not derived from the original neural
cavity.
FORNICOMMISSURE
CALLOSUM
CALLOSUM
PRECOMMISSURE
PRCCOMMISSURAL
REGION
PRECOMMISSURE
C. SUBCALLOSU8
PRECOMMISSURE
C
FIG. 612. — Schemata showing the development of the callosum and its relations to hippocampus, fornix, and
precommissure. Lamina terminalis (terma) in heavy black, callosum dotted. * Represents the attenuated
indusium and longitudinal strise already described.
Development. — The callosum develops as a mass of commissural fibres which grow from
side to side in the terma (lamina terminalis). The terma serves as a matrix for several com-
missural systems, viz., the hippocampal or fornicommissure and the precommissure, in addition
to the callosum. The last develops rapidly in higher mammalian brains, thrusts aside the hippo-
campal margin of the pallium so that it atrophies in large part, and stretches out within its sharply
bent arch a portion of the preeommissural wall of each cerebral vesicle. It thus withdraws
a part of the intercerebral cleft, eventually enclosing it entirely as the pseudocele. The stages
of development are shown schematically in Fig. 612 and its development in the human embryo
is shown in Fig. 613. The callosum is most fully developed in man and does not appear below
the marsupials. Its growth kept pace with the preponderatingly greater development of the
neopallium in higher forms, and it may be looked upon as an index of the elaboration of at least
one division of the association systems — those concerned with bilateral coordinations.
The Lateral Ventricles. — An incision through the callosum, on either side of the
median plane, will expose two large, irregular, symmetrically situated cavities,
the lateral ventricles (paraceles), extending through a great part of each hemi-
cerebrum. Each lateral ventricle communicates with the third ventricle through
a small opening, the porta or foramen of Monro, situated between the fornicolumn
(anterior pillar of fornix) and frontal end of thalamus. The cavity is lined through-
out by endyma; it is narrow in some and wide in other localities, and contains
cerebro-spinal fluid.
The shape of the ventricle is best understood by reference to a cast of its
interior and its location within the cerebrum may be appreciated by a study of
Figs. 614 and 615. Conventionally the paracele or lateral ventricle is described as
being composed of a body or cella and three horn-like extensions or cornua.
Viewed laterally its contour corresponds to that of the cerebral hemisphere and
its cornua project toward the three poles, viz., frontal, occipital, and temporal.
942
THE NERVE SYSTEM
FIG. 613. — Brains of human embryos; mesal aspects of median sagittal section show the development of the
callosum: A, fourth month; B, fifth month; C, sixth month; D, seventh month.
THE CEREBRAL HEMISPHERES
943
The body (pars ccntralis ventriculi lateralis] or cella of the lateral ventricle is
defined as that portion which extends from the porta to the region of the splenium.
Its frontal prolongation is called the precornu. Near the splenium the cavity
may be traced ventro-laterad into a capacious part (trigonum ventriculi), from
which the postcornu and medicornu are prolonged, respectively, toward the
occipital and temporal poles.
The Precornu (cornu anterius) passes frontad, inclined slightly ventro-laterad.
Its floor is the head (caput) of the caudatum, forming a rounded incline sloping
inesad toward a trench-like recess floored by the rostrum of the callosum. Its
roof is the preforceps of the callosum. Its mesal wall is formed by a portion of
the hemiseptum. Laterally it is limited by the apposition, at an acute angle, of
callosum and caudatum. Its apex reaches the ventricular surface of the genu
of the callosum. The general outline of the ventricle, in a frontal section, is
triangular (Fig. 625).
FIG. 614. — Showing the ventricular system of the brain as a solid cast as if seen through a transparent brain.
The body of the cavity is curved with its convexity dorsad; its outline in trans-
sections varies from the triangular to a mere slit which slopes slightly meso-
ventrad. It is wholly roofed in by the callosum (pars frontoparietalis'). Its
floor is formed by the following structures named in order from its ectal toward
its ental limit: (1) caudatum; (2) a groove which marks the line of coalescence of
caudatum and thalamus and lodges the tcenial vein and a narrow fibre-strand—
the tsenia semicircularis, beneath the endyma; (3) a reflexion of the endyma onto
a narrow area of the thalamus; (4) the paraplexus or choroid plexus of the lateral
ventricle; (5) the thin, sharp (fimbriated) edge of the fornix. The caudatum
narrows rapidly as it passes caudad. The tsenia semicircularis, lying along the
ental border of the ventricular surface of the caudatum, is a small band of white
fibres arching from the amygdala (near the temporal pole) to the preperforatum.
The entrance of a part of the thalamus into the formation of the floor of the para-
cele is apparent enough, but morphologically it should be strictly excluded there-
944
THE NERVE SYSTEM
from. The thalamus is in no way formed from the parietes of the secondary
fore-brain vesicle (telencephalon), for it is, in fact, excluded by a layer of endyma
(lamina affixa) reflected onto, and often separable from, the surface of the thala-
mus, so that it appears as a constituent of the floor because of the transparency of
the endymal sheet. The paraplexus is a richly vascular invagination over which
the endyma is continuous to again become reflected onto the fornix along its
HIPPOCAMPAL
DIGITATIONS
COLLATERAL
EMINENCE
^--—^^
FIG. 615. — Dissection showing the left lateral ventricle (paracele) exposed.
sharp edge. A reference to Fig. 608, showing the topographical relations of these
structures in a frontal section, may be of assistance.
The cavity is thence continued ventro-laterad in a bold sweep to become
expanded as an obliquely pyramidal space of a somewhat triangular outline on
section, and placed subjacent to the parietal lobe — the trigonum ventriculi. A
conspicuous feature in its floor is the collateral eminence, correlated with the
THE CEREBRAL HEMISPHERES
945
collateral fissure. From the trigonum, the most capacious part of the paracele,
the cavity is prolonged in opposite directions as the medicornu and postcornu.
The Medicornu (cornu inferius) is a prolongation of the ventricular cavity,
from its trigone toward the temporal pole, which pursues a curved course with its
convexity directed ventro-laterad (Figs. 614 and 615), corresponding to the curved
contour of the temporal lobe, and situated at a depth of about 3 cm. from its
lateral surface as well as from the temporal pole. The roof is formed by (a) the
tapetum of the callosum; (6) the cauda (tail) of the caudatum; (c) the taenia semi-
circularis. The medial wall is principally composed of the hippocampus, a promi-
nent welt-like eminence bulging into the cavity, largely filling it, and produced
by the hippocampal fissure. The hippocampus nearly conceals from view the
actual floor, which is of variable extent in different brains and usually marked by
an extension of the collateral eminence previously described. Surmounting the
FIG. 616. — Diagram showing the topography of the lateral ventricle, medidural artery, and
cerebrum within the cranium.
corrugated hippocampal formation and projecting slightly into the cavity, is the
fimbria, and from its sharp edge the ventricular endyma is reflected upon the
invaginated paraplexus. The paraplexus of the medicornu is more voluminous
than that of the body of the ventricle, and must be lifted in order to expose the
whole of the ventricular aspect of the hippocampus.
At the apex of the medicornu the roof presents a more or less pronounced
bulging, the amygdaloid tubercle, due to the presence of the amygdala, a small
mass of ganglionic gray from which the tsenia semicircularis arises and in which
the caudatum apparently ends.
The Postcornu is a shorter diverticulum which passes toward the occipital
pole in a gently curved course, with its convexity directed laterad. It is not very
capacious, usually slit-like on section, and tapers to a point within 2 or 3 cm. of
the occipital pole. Its roof, slanting latero-ventrad, is formed by the tapetum of the
60
946 THE NERVE SYSTEM
callosum. On the inner or mesal wall two elongated bulgings may be observed.
The upper or dorsal elevation, called the occipital bulb or bulb of the cornu
(bulbus cornu posterioris; callosal eminence [Wilder]), is formed by the compact
arched postforceps of the callosum as it curves around the very deep occipital
fissure. The occipital bulb is not always well marked. Ventrad of it lies a
more constant limbus or welt-like elevation, the calcar (calcar avis; hippocampus
minor}, a projection produced by the infolding of the cerebral wall along the
calcarine fissure. The paraplexus does not enter the postcornu.
The Choroid Fissure or Rima (rima transversa cerebri magna; fissure of
Bichat} is not a true fissure, and only becomes one when the (paraplexus) choroid
plexus of the lateral ventricle is torn from its connections. The rima is never-
theless a gap between the diencephalic part and the overlapping and recurved
telencephalon produced by the extension of the secondary fore-brain vesicle in
an arcuate manner which Hill described by the phrase " rotation of the great
fore-brain." It is along this arcuate and fissure-like gap that the richly vascular
(pial) paraplexus invaginates the atrophied parietes of the secondary fore-brain
to form the paraplexus which is everywhere covered by endyma. The rima
Fie. 617. — Diagram showing the choroid fissure.
extends from the porta to near the tip of the medicornu in an arcuate course and
endymal reflections everywhere close in this gap except at the porta (Fig. 617).
The manner in which this is accomplished may best be understood by a study of
trans-section showing the endymal reflections from the ventricular wall onto the
invaginated paraplexus. The caudato-thalamic fusion and the intrusion of the
great fibre-masses constituting the cerebral crura play their parts in complicating
the relations in brains of higher type.
The Paraplexus and Velum.— The paraplexus is a highly vascular, fringe-like
structure composed of pia which is invaginated into the paracele along the
rima, or gap between hemicerebrum and diencephalon. The portion of the
paraplexus protruding into the "body" of the paracele is the fringed vascular
border — a triangular fold of pia — the velum interpositum (tela chorioidea superior},
which, as its name implies, is interposed between the relatively small primary
fore-brain and the enormous overlapping secondary fore-brain, and is produced by
the overgrowth of the latter onto . the former. Inasmuch as the nerve-tissue in
the roof of the third ventricle atrophies totally, the ventral fold of the pia comes
into contact with the endyma of that ventricle and here permits a similar vascular
invagination in the form of two parallel fringes hanging into the cavity (diaplexus
THE CEREBRAL HEMISPHERES
947
or choroid plexuses of the third ventricle). The dorsal leaf of the pial fold is
in contact with the ventral face of the body of the fornix. Frontad, the velum
tapers toward the region of the two portse, where the paraplexuses of the two
sides are continuous with each other. The ventricular surface of the choroid
plexuses is everywhere covered by endyma which is reflected from it to the fim-
briated edge of the fornix on the one hand and to the line of the tsenia semicircu-
laris (over the thalamus by the lamina affixa) on the other. Its vascular com-
ponents, in addition to undefined lymphatic channels, are: the prechoroid (anterior
choroid} artery, a branch of the internal carotid, entering the paraplexus of the
medicornu; the postchoroid (posterior choroid} artery from the postcerebral artery
reaching the paraplexus in the neighborhood of the splenium. The venules of the
plexus join to form a tortuous medicornual vein which terminates frontad by
joining one of the velar veins.
Fornix
Thalamus
Quadrigemina
Fie. 618. — Diagram showing the mode of formation of the velum.
The velar veins (veins of Galen}, one on each side close to the median line,
running in the fold of the velum, are formed by the union of the tsenial, striatal,
and medicornual veins. The two velar veins unite to form a common trunk
which empties into the straight sinus.
The Hippocampus and Fornix. — The hippocampus and the fornix merit special
description. The hippocampus, as seen in the medicornu, is a white eminence
about 5 cm. in length, of a curved elongated form, enlarging cephalad and tapering
caudad as the hippocampal fissure decreases in depth. The enlarged extremity
is marked by alternate elevations and depressions, usually three in number, the
hippocampal digitations; because of its resemblance to a lion's paw it is sometimes
called the pes leonis or pes hippocampi. The white appearance of the ventricular
aspect of the hippocampus is due to a stratum of white substance, the alveus, made
up of myelinic axones from hippocampal cells and continued into the fimbria.
The fimbria is folded so that its sharp margin is directed toward the cavity of
the medicornu; eventually its fibres will be seen to enter into the formation of the
fornix. The formation of the hippocampus is best observed in a coronal section
(Fig. 008). In this view it is seen to be a peculiarly folded margin of the cere-
bral cortex, corrugated by the intrusion of the hippocampal and fimbriodentate
948
THE NERVE SYSTEM
fissures. Morphologically it is a vestigial submerged portion of the rhinencephalon,
as a part of which it has already been described.
FIG. 619. — The fornix, velum, and medicornu of the lateral ventricle.
Eminentia
collateralis.
Hippocampus
Gray substance )
of the >
hippocampus. J
f Fascia
( (I I'll III /H.
f Hippocampal
(gyre
Uncinate
process or
uncus.
FIG. 620.— Transverse section of the middle horn of the lateral ventricle.
THE CEREBRAL HEMISPHERES
949
The fornix (Figs. 615, 621, 622) is really a paired structure consisting of bilaterally
symmetrical halves composed of longitudinally directed fibres which arch on each
side from the region of the uncus to the albicans. The two lateral parts join each
FRENULUM
GIACOMINI
FORN (COM-
MISSURE
FIG. 621. — The fornix, fornicommissure, splenium, and dentate gyre seen from the basal aspect.
FIG. 622. — Diagram of the fornix.
other in the mesal plane along the summit of the arch to form the body of the fornix
(corpus fornicis). Frontad they diverge slightly as they proceed toward the albi-
cantia ; caudad they diverge more widely. The paired diverging portions are called
950
THE NERVE SYSTEM
respectively the anterior and posterior pillars of the fornix. The fibres of each half-
fornix arise from the pyramidal cells in the hippocampus and their course will
CALLOSUM
CAUDATUM
(CAPUT)
PRECORNU OFLATERAL
VENTRICLE
CALLOSUM
(ROSTRUM)
PSEUDOCELE
FIG. 623. — A frontal section of the brain slightly caudad of the genu of the callosum.
be traced from this source to the ending in the albicans. Beginning at first as a
stratum of white substance (alveus) constituting the ectal surface of the ventricular
CALLOSUM
PRECORNU OF LATERAL'
VENTRICLE
CALLOSUM
(ROSTRUM)
CLAUSTRUM
FIG. 624.— A frontal section through the brain in the plane of the junction of caudatum and lenticula.
bulge of the hippocampus, the fibres become collected along its medial border
in a narrow but distinct folded band, the fimbria. This increases in calibre
THE CEREBRAL HEMISPHERES
951
as increments are added to it along its course, until, at the apical region of the
trigonum ventriculi, it leaves the dwindling hippocampus to ascend in a curved
course (dorsi-mesad) toward the subsplenial callosal surface as a thick, flattened
band. Once free from the hippocampus on each side, the two converging bands
of opposite sides are called the posterior pillars or crura fornicis. The majority
of the fibres continue frontad in each half-fornix, but a number course
transversely to enter the crus fornicis of the opposite side to end in the hippo-
campal formation. These fibres, of transverse course, form a thin lamina filling
in the small triangular space in the subsplenial region between the converging
crura fornicis and constituting the fornicommissure (Lyra; psalterium; hippocampal
commissure). Occasionally a small recess called Verga's ventricle is formed
between callosum and fornicommissure.
The two half-fornices now become joined in the mesal plane and, leaving the
subsplenial surface of the callosum, dip fronto-ventrad in dn arch — the body of the
fornix. Its caudal part is broad and each half is of triangular outline (on section)
with a sharp edge directed laterad. Where it is not in contact with the callosum
LATERAL VENTRICLE
INTERNAL CAPSULE
FORNICOLUMN
CLAUSTRUM
PRECOMMISSURE
AMYGDALA
FIG. 625. — A frontal section of the brain in the plane of the precommissure.
it affords attachment, on each side of the mesal plane, to the hemiseptum.
Laterad of these lines of attachment the dorsal surface of each fornix enters into
the formation of the floor of the lateral ventricle and is covered by endyma (Fig.
615). The ventral surface rests upon the velum, which separates it from the
third ventricle and the dorsal surface of the thalamus.
Near the region of the precommissure the fornix again divides into its con-
stituent lateral halves, separating as rounded strands called the fornicolumns or
anterior pillars. These curve ventrad to form the frontal boundary of the porta
and thence plunge into the hypothalamic gray, inclined slightly caudad, to end
in the albicans. The terminals of the fornix fibres come into relation with the
cells of the nucleus of the albicans, which in turn give off the bifurcating Y-shaped
axone-bundles already described (p. 920).
In rare instances each fornicolumn has been seen. to divide on, approaching the
precommissure, a part passing frontad thereof as an anomalous precommissural
952 THE NERVE SYSTEM
fornicolumn. The fornix, in its course from hippocampus to albicans, gives off,
in addition to those described as hippocampal commissural fibres, axones (a) to
the opposite half-fornix, decussating in the fused portion (body), (6) to the
hemiseptum, and (c) to the gray tissues of the preperforatum (Fig. 607). It
constitutes an inner olfactory arc as distinguished from the epicallosal or outer
arc, represented by the atrophied indusium and its longitudinal strise.
The Septum Lucidum (septum pellucidum). — The so-called septum lucidum
really consists of two vertically placed laminae or hemisepta. Between them lies
a narrow, enclosed space, the pseudocele or fifth ventricle (cavum septi pellucida),
roofed in by the calfosum, while the floor consists of the fused fornices and the
rostrum. Each hemiseptum bounds a part of the precornu and body of the
paracele in its mesal wall and in a lateral view is of triangular outline. The
hemisepta represent the thin, undeveloped parts of the mesal walls of the cerebral
vesicles, which were enclosed within the rapidly developing arch of the callosum.
The pseudocele is therefore a closed-off part of the original intercerebral cleft and
not a part of the neural cavity as its older name "fifth ventricle" seems to imply.
The Precommissure. — The precommissure is a bundle of white fibres, of oval
outline in a sagittal section, which crosses the mid-line as a localized reenforce-
ment of the terma, slightly bulging into the frontal part (aula) of the third ventricle
and clothed by its endyma. It is a comparatively insignificant intercerebral
commissure in the human brain, having become diminished as the callosum
increased in mammalian development. It courses from side to side frontad of the
fornicolumns, ventrad of the head of the caudatum, and passes, in part, through
the frontal end of the lenticula. Its fibres radiate chiefly to the cortex of the
temporal lobe and to certain parts of the rhinencephalon.
The bundle is slightly twisted in each lateral, buried part. Two divisions are
distinguishable: 1. The pars anterior or frontal part (in the median plane) con-
tains two groups of fibres belonging to the olfactory apparatus: (a) fibres arising
from the mitral cells in the olfactory bulb of one side to the same layer in the
opposite bulb; (6) fibres which associate the uncus of one side with that of the
other. 2. The pars posterior contains the fibres passing between the cortices of
the two temporal lobes.
Gray Masses in the Hemicerebrum. — Aside from the cortex, the hemicerebrum
contains certain gray ganglionic masses in its interior, more or less embedded in
the white centrum and called, because of their proximity to the base of the cere-
brum, the basal ganglia. These comprise the caudatum, the lenticula, and the
amygdala. It is usual to include the claustrum among the basal ganglia, but
morphologically this structure belongs rather to the insular cortex.
Conventionally the caudatum and lenticula together are described as the
striatum (corpus striatum) — a ganglionic mass which in earlier vertebrate brains
bore intimate relations with the olfactory apparatus, but later, with the rise in
functional dignity and growth of the neopallium, underwent specialization and
differentiation concomitant with the reduction of the rhinencephalon. The
intrusion of great projection fibre-masses, thrusting the cortical gray outward,
has not been everywhere uniform, and we still find, in the human brain, a common
ground in which the neopallial cortical gray, the striatum, rhinencephalon, and
amygdala meet — the site of fusion being in the gray substance of the preperforatum.
To the cortical mantle they are regarded as bearing the relation of subordinate
(subcortical) centres. In the human brain the striatum — so-called because of its
striated appearance in sections — is composed of two masses, the caudatum and
lenticula, directly continuous with each other at their frontal ends (Fig. 627).
The connecting gray bridge becomes broken up into numerous small bands of
gray substance as the fibre-masses of the internal capsule insinuate themselves
between the two" nuclei (Fig. 624).
THE CEREBRAL HEMISPHERES 953
The Caudatum (nucleus caudatus] (Figs. 623, 626, 627) presents a ventricular
and a capsular surface; the ventricular surface, covered by endyma, forms part
of the floor of the body and precornu, while in the medicornu it is a constituent of
its roof, owing to its arched contour in correspondence with the sweeping curve
of the ventricle itself. It is of a pyriform shape with a very much attenuated tail.
The large, thick head projects into the precornu whilst its thinner tail is pro-
longed caudo-laterad, separated from the thalamus by the narrow taenia semi-
circularis. Following the curved contour of -the ventricle it is prolonged as a
FIG. 626. — The basal ganglia and thalamus schematically represented in a supposedly transparent brain
(right side); on the left is shown the outline of the paracele (lateral ventricle).
narrow gray band in the roof of the medicornu. where it joins the amygdala. The
non-ventricular or capsular surface is embedded in the white substance of the
hemi-cerebrum, and is chiefly related to the internal capsule.
The ventricular surface shows, in microscopic sections, a dense endymal
lining. The capsular face is not sharply outlined, numerous strands of fibres,
to and from the internal capsule, entering it obliquely so as to appear as streaks
954
THE NERVE SYSTEM
AMYGDALA
which extend to about the middle of the ganglion, there separating into finer
and finer strands which become lost to the naked eye.
The Lenticula (Figs. 624, 626, 628) is wholly embedded in the white substance
and must be studied in sections. In its shape it resembles an irregular trian-
gular pyramid with its convex base directed laterad and parallel with and near
to the cortical expanse of the insula and of about the same extent. Its ental,
apical portion is directed toward the interval between caudattim (head) and
thalamus. The contour and slope of the surfaces of the ental pyramidal face
may be judged from the model pictured in Fig. 627. Its outline, as revealed in
sections passing in different planes, is shown in Figs. 625 and 628.
Sections of the lenticula show it to be composed of three1 concentric segments
separated by two white medullary laminae. The segments are known as articuli;
the ectal one is designated the putamen; the two ental zones constitute the palli-
dum (globus pallidus). The putamen is
the larger and of a deeper reddish-gray
tint; the two mesal divisions are lighter
in color owing to a greater proportion of
radiating streaks of white fibres passing
to and from the internal capsule. The
ectal outline of the putamen is sharply
defined against a white lamina, the external
capsule.
The Amygdala is usually regarded as an
hypertrophied aggregation of the tem-
poral cortex which has become nearly
isolated from its cortical connection by
intruding white substance. It is a
rounded, gray, striated mass situated in
the forepart of the temporal lobe in the
roof of the medicornu at its apex, where
it produces the bulging called the amygda-
loid tubercle. Caudad it is joined by the
tail of the caudatum; frontad it is contin-
uous with the putamen. Except for the
marked streaking shown in sections, its
structure is like that of the cortex. Its
cells apparently give rise to the narrow
band of fibres — the tsenia semicircularis —
which courses along the mesal margin of
the ventricular surface of the caudatum
throughout its arched course and ends in the preperforatal gray so that it nearly
completes a circle.
The Claustrum is a thin plate of gray substance embedded in the white sub-
stance which intervenes between the putamen and the insular cortex, and corre-
sponding in extent to these. Its dorsal edge is very much attenuated; traced
ventrad it thickens considerably and becomes continuous with the surface gray at
the preperforatum. Its ectal surface presents alternate ridges and depressions
which correspond to the corrugations of the insular cortex. The "external
capsule" intervenes between its ental face and the putamen of the lenticula. From
the insular cortex proper it is separated by a white lamina which may be termed
the periclaustral lamina or capsula extrema. Apparently the claustrum is the
thickened and isolated spindle-cell stratum of the insular cortex, a feature which
B
AMYGDALA
FIG. 627. — Two views of a model of the striatum
A, lateral view aspect; B, mesal view aspect.
1 Four and even five have been observed.
THE CEREBRAL HEMISPHERES
955
may be of significance in relation to the preponderatingly associative function of
the insular region.
Internal Capsule (Fig. 628). — Between the lenticula on the one hand and the cau-
latum and thalamus on the other lies the internal capsule, a broad band of white
fibres which, as seen on horizontal section, appears bent, very much as a leg is bent
on the thigh, with the knee (genu) directed mesad. The frontal or caudatp-len-
ticular division or limb is confined between the opposed faces of the caudatum and
lenticula. The genu receives the mesal apex of the lenticula in its hollow, while
PRECORNU OF
LAT. VENTR.
PSEUDOCELE
CORTEX OF INSULA
FORNIX
CLAUSTRUM
EXTERNAL CAPSULE —
ALBICANTIO-
THALAMIC TR.
PARACLAUSTRA
WHITE LAMINA
EPIPHYSIS
TAIL OF CAUDATUM
HIPPOCAMPUS
CHOROID PLEXUS
OPTIC RADIATION
TAPETUM
CALCARINE
FISSURE
WHITE STRIPE OF
VICQ D'AZYR
FIG. 628. — Horizontal section through the cerebrum. The various structures are shown in their natural
appearance on the right side and are named on the left side.
the caudal or thalamo-lenticular limb lies between the opposed faces of lenticula
and thalamus. The frontal limb constitutes about one-third, the caudal limb
two-thirds of the internal capsule mass.
The term "internal capsule" is often loosely employed and is variously stated
to include fibre-tracts which do not course between the cerebral cortex and the
"lower" brain centres. In a strict sense it is a mass of fibres which converge,
like the sticks of a fan, toward the cerebral base and into the crusta. Dorsad
of the basal ganglia the fibres radiate in various directions, streaming among
the radiating callosal fibres and forming the so-called corona radiata. Yet other
THE NER VE SYSTEM
TH A LA MO-
FRONTAL
TRACT
GENICULATE
PORTION OF
MOTOR TRACT
(FOR MUSCLES'"
OF FACE AND
TONGUE)
fibre-tracts leave and enter the great ganglia at various altitudes along the internal
capsule, and we must therefore distinguish the following cerebral fibre-systems .
Projecting systems, ascending and descending (in the functional sense), of
longer and shorter course, connecting the cerebral cortex with (a) spinal gray
centres; (6) mid-brain and pontile nuclei; (c) basal ganglia and thalamus. The
last-mentioned system traverses the internal capsule to a greater or lesser extent,
but does not continue into the
crusta. These various systems
are summarized on page 963. It
may here be mentioned that the
internal capsule, topograpically,
exhibits a functional dissociation
in that its frontal or lenticulo-
caudate limb is composed of pre-
ponderatingly corticipetal fibres,
while corticifugal fibres form the
major portion of the thalamo-
lenticular limb (Fig. 629). In
the frontal limb are the thalamo-
frontal and thalamo-striate fibres;
the former ending in the cortex
of the frontal lobe, the latter in
the caudatum and lenticula. The
chief corticifugal components are
the fronto-pontile tract, and fewer
fronto-thalamic and striato-thala-
mic fibres. The fronto-pontile
tract arises in the cortex of the
pref rental region, traverses the
frontal limb of the internal cap-
sule, forms the ental sector (one-
fifth) of the crusta, and ends in
the nuclei pontis.
In the genu and the thalamo-
lenticular limb of the internal
capsule course several important
fibre-tracts which are chiefly cor-
ticifugal.
The Pyramidal (Motor) Tract,
in its course from the precentral
cortex to the lower motor centres
occupies the frontal half of this
limb. The portion in the genu,
often designated the geniculate
tract, comprises the pyramidal
fibres which are destined to go
to the facial and hypoglossal
nerve nuclei; further caudad lie, in succession, the fibres going to the motor
centres for the upper and the lower extremity. The most caudal segment (also
called the retrolenticular part) of the internal capsule contains (a) the optic radia-
tion, composed of fibres coursing in both directions between the occipital cortex
and the pulvinar, pregeniculum and pregeminum; (6) the auditory radiation, com-
posed of fibres passing in both directions between the cortex of the temporal
lobe (auditory centre) and the postgeminum and postgeniculum ; (c) the occipito-
OPTIC
RADIATION
FIG. 629. — Diagram of the tracts in the internal capsule.
Motor tract red. The sensor tract (blue) is not direct but
formed of neurones receiving impulses irom below in the
thalamus and transmitting them to the cortex. The optic
radiation (occipito-thalamic) is shown in violet.
THE CEREBRAL HEMISPHERES
957
pontile and temporo-pontile tracts from the occipital and part of the temporal
cortex, coursing through the caudal segment of the internal capsule, constituting
the ectal (one-fifth) sector of the crusta and ending in the nuclei pontis. In ad-
dition there are scattered fibre-bundles which arise from the ventral portion of
FIG. 630.— Diagram of motor path from right brain. The upper segment is black, the lower red. The nuclei
of the motor cerebral nerves are shown on the left side: on the right side the craniaj nerves of that side are
indicated. A lesion at 1 would cause upper segment paralysis in the arm of the opposite side — cerebral mono-
plegia; at 2, upper segment paralysis of the whole opposite side of the body — hemiplegia; at 3, upper segment
paralysis of the opposite face, arm, and leg, and lower segment paralysis of the eye muscles on the same side —
crossed paralysis; at 4, upper segment paralysis of opposite arm and leg, and lower segment paralysis of
the face and the external rectus on the same side — crossed paralysis; at 5, upper segment paralysis of all mus-
cles below lesion, and lower segment paralysis of muscles represented at level of lesion-^spinal paraplegia; at
6, lower segment paralysis of muscles localized at seat of lesion — anterior poliomyelitis. (Van Gehuchten,
modified.)
the thalamus, enter the internal capsule to pass toward the cortex, in part through
the lenticula, in part in the sublenticular zone, to form the ansa lenticularis. The
reenforcement of this sublenticular white-fibre tract by cortico-thalamic fibres from
the temporal lobe to thalamus forms the ansa peduncularis. The topographic rela-
tions of the various tract-masses as seen in a flat-wise section is schematically
958
THE NERVE SYS1EM
\
MOLECULAR LAYER
ECTAL POLYMOR-
PHOUS CELL LAYER
a
ft
LAYER OF SMALL
> PYRAMIDAL CELLS
shown in Fig. 630; on the whole they correspond to the cortical areas with
which they are connected.
The External Capsule (Fig. 628).— The external capsule is a thin lamina of white
substance interposed between the ectal face of the lenticula and the claustrum
Dprsally, frontad and caudad, at the corresponding borders of the lenticula it
joins the internal capsule mass, while ventrally it is continuous with the white
centrum of the temporal lobe. Its compara-
tively few projection fibres course to and
from the ventral parts of the thalamus; its
chief constituents are association axones for
the circuminsular cortical areas.
Intimate Structure of the Cerebral Cortex and
its Special Types in Different Regions (Fig.
631). — A section of the cerebral cortex re-
veals a tendency on the part of its constituent
cells to arrange themselves in layers which
alternate with zones less rich in cellular ele-
ments. Among the cells course the axones
arising from them or terminating in their
neighborhood. The axones are chiefly amye-
linic, though some are myelinic for a part
of their intracortical course. The cells, of
various sizes and shapes, together with their
dendrites and axones are embedded in a
matrix of neuroglia.
The nerve-cells in a typical section of the
cortex are arranged in five tangential layers,
as follows: (1) the molecular layer; (2) the
ectal polymorphous cell layer; (3) the layer of
small pyramidal cells; (4) the layer of large
pyramidal cells; (5) the ental polymorphous
cell layer.
The molecular layer (neuroglia layer] lies
immediately subjacent to the pia and is
chiefly made up of glia cells and fibres
amongst which the dendrites of the subjacent
layer of cells intrude.
The ectal polymorphous layer cells are poly-
gonal, triangular and fusiform in shape and
tend to gather in groups in certain cortical
regions. The fusiform cells are placed with
their long axes parallel (i. e., tangential) to
the gyral surface and are presumably associa-
tive in function.
The Layer of Small and the Layer of Large
Pyramidal Cells. — The cells in the second
and third layers may be studied together,
since, with the exception of the difference
in size and the more superficial position of the
smaller cells, they resemble each other. The body of each cell is pyramidal in
shape, its base being directed to the deeper parts and its apex toward the sur-
face. It contains granular pigment, and stains deeply with ordinary reagents.
The nucleus is nucleolated, of large size, and round or oval in shape. The base
of the cell gives off the axone, and this passes into the central white substance,
LAYER OF LARGE
PYRAMIDAL CELLS
ENTAL POLYMOR-
PHOUS CELL LAYER
FIG. 631. — Typical arrangement of the cell
layers in the cerebral cortex.
THE CEREBRAL HEMISPHERES 959
giving off collaterals in its course to be distributed as a projection, commissural,
or association fibres. Both the apical and basal parts of the cell give off dendrites.
The apical dendrite is directed toward the surface, and ends in the molecular
layer by dividing into numerous branches, all of which may be seen to be studded
with projecting bristle-like processes when prepared by the silver or methylene-
blue method. The larger pyramidal cells, especially in the precentral gyre,
may exceed 50 fj. in length and 40 /* in breadth, and are termed giant cells. The
chief function of the small pyramidal cells is commissural and associative.
The chief function of the large pyramids is motor, but they have also commissural
and associative functions.
Layer of Ental Polymorphous Cells. — The cells in this layer, as their name
implies, vary greatly in contour, the commonest varieties being of a spindle,
star, oval, or triangular shape. Their dendrites are directed outward, toward,
but do not reach, the molecular layer; their axones pass into the subjacent white
substance. From this layer come commissural fibres, long association fibres, and
some projection fibres.
There are two other kinds of cells in the cerebral cortex, but their axones pass
in a direction opposite to that of the pyramidal and polymorphous cells, among
which they lie. They are: (a) the cells of Golgi, the axones of which do not
become myelinated, but divide immediately after their origin into a large number
of branches, which are directed toward the surface of the cortex; (6) the cells of
Martinotti, which are chiefly found in the polymorphous layer. Their dendrites
are short, and may have an ascending or descending course, while their axones
pass out into the molecular layer and form an extensive horizontal arborization.
Nerve-fibres in the Cortex. — These fill up a large part of the intervals between
the cells. Some of these fibres form fasciculi; some are isolated, and others are
arranged in plexuses. They may be myelinic or amyelinic, the latter comprising
the axones of the smallest pyramidal cells and the cells of Golgi. In their direction
the fibres may be either transverse, the transverse tangential or horizontal fibres,
or vertical, the vertical or radial fibres. The transverse fibres run parallel to the
surface of the hemisphere, intersecting the vertical fibres at a right angle. They
consist of several strata, of which the following are the most important: (1) a
stratum of white fibres covering the superficial aspect of the molecular layer; (2)
the band of Bechterew, found in certain parts of the superficial portion of the
layer of the smaller pyramidal cells; (3) the external or outer band of Baillarger
or the band of Gennari, which runs through the layer of large pyramidal cells;
(4) the internal band of Baillarger, which intervenes between the layer of large
pyramidal cells and the polymorphous layer. According to Cajal, the transverse
fibres consist of (a) the collaterals of the pyramidal and polymorphous cells and
of the cells of Martinotti; (6) the arborizations of the axones of Golgi 's cells; (c)
the collaterals and terminal arborizations of the projection, commissural, or
association fibres. The vertical fibres: Some of these, viz., the axones of the
pyramidal and polymorphous cells, are directed toward the central white sub-
stance, while others, the terminations of the commissural, projection, or association
fibres, pass outward to end in the cortex. The axones of the cells of Martinotti
are also ascending fibres.
In certain parts of the cortex this typical structure is departed from. The chief
of these regions are: (1) the occipital lobe, (2) the transtemporal gyres, (3) the hippo-
campus, (4) the dentate, and (5) the olfactory bulb.
Special Types of Gray Substance. 1. The Occipital Lobe. — In -the cuneus and
the calcarine fissure of the occipital lobe, Cajal has recently described as many as
nine layers. Here the inner band of Baillarger is absent; the outer band of Bail-
larger or band of Gennari is, on the other hand, of considerable thickness. If a
section be examined microscopically, an additional layer is seen to be interpolated
960 THE NER VE SYSTEM
between the molecular layer and the layer of small pyramidal cells. This extra
layer consists of two or three strata of fusiform cells, the long axes of which are at
right angles to the surface. Each cell gives off two dendrites, external and internal,
from thS latter of which the axone arises and passes into the white central sub-
stance. In the layer of small pyramidal cells, fusiform cells, identical with the
above, are seen, as well as ovoid or star-like elements with ascending axones, the
cells of Martinotti. This area of the cortex forms the visual centre, and it has
been shown by Dr. J. S. Bolton1 that in old-standing cases of optic atrophy the
thickness of Gennari's band is reduced by nearly 50 per cent.
2. The Transtemporal Gyres. — The transtemporal gyres are distinguished by a
reduction of thickness of the pyramidal cell layer with closer approximation of
the giant-cells to each other, while the fusiform cell layer is more deeply situated
than elsewhere. This cortical formation is the end-station for cochlear nerve
projections.
3. The Hippocampus. — In the hippocampus the molecular layer is very thick
and contains a large number of Golgi cells. It has been divided into three
strata: (a) S. convolutum or S. granulosum, containing many tangential fibres; (6)
S. lacunosum, presenting numerous lymphatic or vascular spaces; (c) S. radiatum,
exhibiting a rich plexus of fibrils. The two layers of pyramidal cells are con-
densed into one, and these are mostly of large size. The axones of the cells in
the polymorphous layer may run in an ascending, descending, or horizontal
direction. Between the polymorphous layer and the ventricular ependyma is
the white substance of the alveus (Fig. 608).
4. The Dentate Gyre. — In the rudimentary dentate convolution the molec-
ular layer contains some pyramidal cells, while the pyramidal layer is almost
entirely represented by small ovoid elements.
5. The Olfactory Bulb. — In many of the lower animals this contains a cavity
which communicates through the hollow olfactory stalk with the cavity of the
lateral ventricle. In man the original cavity is filled by neuroglia and its wall
becomes thickened, but much more so on its ventral than on its dorsal aspect.
Its dorsal part contains a small amount of gray and white substance, but this is
scanty and ill defined. A section through the ventral part shows it to consist of the
following layers from without inward. (1) A layer of olfactory-nerve fibres, which
are the myelinated axones prolonged from the olfactory cells of the nose, and
which reach the bulb by passing through the cribriform plate of the ethmoid bone.
At first they cover the bulb, and then penetrate it to end by forming synapses
with the dendrites of the mitral cells, presently to be described. (2) Glomerular
layer (stratum glomerulosum) : This contains numerous spheroidal reticulated
enlargements, termed glomeruli, which are produced by the branching and arbor-
ization of the processes of the olfactory nerve-fibres with the descending dendrites
of the mitral cells. (3) Molecular layer: This layer is formed of a matrix of
neuroglia, embedded in which are the mitral cells. These cells are pyramidal in
shape, and the basal part of each gives off a thick dendrite which descends into
the glomerular layer, where it arborizes as above, or, on the other hand,
interlaces with similar dendrites of neighboring mitral cells. The axones pass
through the next layer into the white substance of the bulb, from which, after becom-
ing bent on themselves at a right angle, they are continued into the olfactory tract.
(4) Nerve-fibre layer: This lies next the central core of neuroglia, and its fibres
consist of the axones or afferent processes of the mitral cells which are passing on
their way to the brain; some efferent fibres are, however, also present, and
terminate in the molecular layer and presumably come via the precommissure
from the mitral cells of the opposite bulb.
1 Phil. Trans, of Royal Society, Series B, vol. cxciii, p. 165.
'"'
EMERSON
THE CEREBRAL HEMISPHERES
961
The claustnim, although usually enumerated among the basal ganglia, is
probably the thickened and isolated deepest layer of fusiform cells belonging to
the cortex of the insula. The white lamina1 intervening between it and the cortex
proper consists of association axones of longer and shorter course.
Summary of the Cerebral Fibre Systems. — The white substance of the cerebrum
consists of myelinic fibres intricately interwoven but permitting of classification
into three systems arranged according to the course they take. These systems
comprise: (1) association fibres, which connect neighboring or distant parts
within the same hemicerebrum ; (2) commissural fibres, which unite allied parts in
the two cerebral halves and come transversely across the mid-line to form the
commissures; (3) projection fibres, which connect the cerebral cortex with lower
centres in the brain and spinal cord, and, conversely, those fibres which connect
lower centres with the cerebral cortex.
1. The Association Fibres (Fig. 632) connect different structures in the
same hemispheres, and are in or near to the cortex. They take origin from the
small pyramidal and polymorphous cells of the deep layer of the cortex. Their
FIG. 632. — Diagram showing the principal systems of associating fibres in the cerebrum.
direction is parallel to the surface of the hemisphere, and in their course they
cross the projection and commissural fibres. They are of two kinds: (1) those
which unite adjacent convolutions, short association fibres; (2) those which pass
between more distant parts in the same hemisphere, long association fibres.
The short association fibres are situated immediately beneath the gray cortex of
the hemispheres, and connect together adjacent convolutions. They constitute
subcortical tracts and are divided into arcuate fibres and tangential fibres. Some
of these fibres connect the "visual sensor area with the visual memory area, and
the auditory sensor with the auditory memory area."
The long association fibres associate cerebral centres which are far apart. They
are gathered into bundles and dip down deep into the centrum ovale. They
include the following: (a) the uncinate fasciculus; (6) the superior longitudinal
fasciculus; (c) the inferior longitudinal fasciculus (doubtful); (d] the cingulum; and
(e),the fasciculus rectus.
1 Previously described as the periclaustral lamina or capsula extrema.
61
962
THE NER VE SYSTEM
(a) The UNCINATE FASCICULUS (/. uncinatus) passes between the uncinate
gyre and the orbital portion of the frontal lobe; in its course it curves beneath the
depths of the basisylvian fissure (Fig. 632).
(b) The SUPERIOR LONGITUDINAL FASCICULUS (fasciculus longitudinalis supe-
rior} (Fig. 632). — The superior longitudinal fasciculus is beneath the convex
surface of the hemisphere. It joins the frontal cortex with the parietal and tem-
poral cortex and brings into relation the motor speech centres and the centres of
auditory and visual memories.
(c) The INFERIOR LONGITUDINAL FASCICULUS is usually described as a tract
associating the centres of auditory and visual memory. Such association fibres
undoubtedly exist, but it is doubtful whether they are collected into a distinct
FIG. 633. — The projection tracts joining the cortex with lower nerve centres. Sagittal section showing the
arrangements of tracts in the internal capsule: A, tract from the frontal lobe to the frontal half of the
capsule, thence in part to the optic thalamus, A2, and in part to the pons, and thus to the cerebellar hemi-
sphere of the opposite side; B, motor tract from the central convolutions to the fascial nucleus in the pons and
to the spinal cord; C, sensor tract from dorsal columns of the cord, through the dorsal or caudal part of the
oblongata, pons, crus, and capsule to the parietal lobe; D, visual tract from the optic thalamus (OT) to the
occipital lobe; E, auditory tract from the internal geniculate body (to which a tract passes from the VIII N.
nucleus) to the temporal lobe; F, prepeduncle; G, jnedi peduncle; H, postpeduncle; CN, caudate nucleus;
CQ, quadrigemina. The numerals refer to the cranial nerves. (Starr.)
fasciculus. The bundle which is usually designated by this term has been proved
to be in part the projection system between the occipital cortex and the thalamus
and pregeniculum (E. Redlich) and in part also the fibres from the temporal
cortex (meditemporal and subtemporal gyre) to the crusta.
(d) The CINGULUM, also called the fornix periphericus, is a band of white
fibres that course in the white substance of the callosal gyre and runs excentrically
to the callosum. Its fibres may be traced frontad into the mesal olfactory stria
and the preperforatum, while caudad they radiate into the hippocampus. It
may be regarded as an association tract of the rhinencephalon akin to the fornix.
(e) The FASCICULUS RECTUS or PERPENDICULAR FASCICULUS runs dorso-
ventrad in the occipito-parietal transition and associates the subparietal gyres
THE CEREBRAL HEMISPHERES 963
with the medi- and subtemporal gyres; a part of the fasciculus associates the dorsal
occipital region with its ventral part and with the subcollateral gyre (Fig. 632).
The FORNIX, previously described, may be enumerated among the long associa-
tion tracts; it belongs exclusively to the olfactory apparatus.
'2. The Commissural Fibres are grouped under the following heads: (a) the
callosum, described on p. 939; (6) the precommissure, described on p. 952; and (c)
the fornicommissure, described on p. 951.
3. The Projection Fibres connect the cerebral cortex with lower brain centres
(caudatum and lenticula, thalamus, hypothalamic region, quadrigemina, pons,
oblongata), and with the spinal cord centres. They either project impulses from
the cortex to the periphery or bring in impressions from without. Their radiations
to and from the cortex, together with the radiations of the ca"llosal fibres, give
rise to the characteristic appearance of the corona radiata. We may distinguish
the projection tracts of long course from those of short course and, in the func-
tional sense, those that are centrifugal, descending or motor, from those that are
centripetal, ascending, or sensor. The latter mode of classification is more
desirable.
1. DESCENDING (corticifugal) TRACTS are composed of axones arising from
the cortical pyramidal cells.
(a) The pyramidal or motor tract from the "motor area," comprising the pre-
central gyre and paracentral gyre, courses through the genu and frontal two-thirds of
the thalamo-lenticular limb of the internal capsule, forms the middle (three-fifths)
sector of the crusta, passes through the pons into the postoblongata and spinal
cord. The tract may be subdivided into a cortico-bulbar and a cortico-spinal division.
The cortico-bulbar division is the pyramidal tract to the efferent cranial-nerve
nuclei. Only those fibres which are destined to go to the facial and hypoglossal
can be traced throughout. They originate in the ventral part of the precentral
gyre (face and tongue centre), course through the genu of the internal capsule and
end, contralaterally, in relation with the facial and hypoglossal-nerve nuclei (also
called the emissary speech tract).
The cortico-spinal division arises from the remainder of the motor area, courses
through the frontal two-thirds of the internal capsule, through crusta, pons, and
postoblongata, to form the pyramids, and undergoing partial decussation, forms
the direct and the crossed pyramidal tracts described in the spinal cord.
(6) The fronto-pontile tract (Arnold's bundle) arises in the midfrontal cortex,
courses through the internal capsule (caudal part of frontal limb), forms the mesal
sector (one-fifth) of the crusta, and ends in the nuclei pontis.
(c) The temporo-pontile tract (Tiirck's bundle) arises in the cortex of the tem-
poral lobe, descends through the internal capsule (caudal segment), forms the ectal
(one-fifth) sector of the crusta, and ends in the nuclei pontis. The existence of
occipito-pontile fibres is denied by Archambault in a recent contribution (1906).
(d) The occipito-mesencephalic tract arises in the visual area (cuneus and
calcarine formation), courses through the retrolenticular part of the internal
capsule, to end in the pregeminum and in relation with the nuclei for movements
of the eyeball.
(e) Part of the fibres composing the optic radiation are corticipetal, arising in
the occipital cortex and ending in the pulvinar of the thalamus and the pregenic-
ulum.
2. ASCENDING (corticipetal) TRACTS arise mostly from the nuclei of the thalamus
and hypothalamus, mid-brain, and cerebellum.
(a) The terminal or cerebral part of the general sensor pathway of the body
comprises the axones arising in the cells of the lateral nucleus of the thalamus
and the hypothalamic nucleus — interposed way-stations which transfer the im-
pressions carried along the medial lemniscus from the nuclei of the gracile and
964
THE NERVE SYSTEM
cuneate fasciculi in the myeloblongata transition. They convey sensor impres-
sions from the body periphery to the somsesthetic area of the cortex — chiefly the
postcentral and parietal gyres.
(6) The terminal or cerebral part of the general sensor pathway of the head and
neck comprises the axones which arise from the afferent cranial-nerve nuclei
(excepting the auditory) and course along the medial lemniscus to the thalamus and
hypothalamic nucleus, to be thence projected to the somsesthetic cerebral cortex.
(c) The terminal or cerebral part of the auditory pathway from the postgeminum,
postgeniculum, and the interposed nucleus of the lateral lemniscus, ending in the
auditory sphere of the cerebral cortex.
(d) The terminal part of the visual pathway, described on pages 919.
(e) The terminal (ascending] cerebello-cortical pathway, arising as the fibres of
the cerebellar prepeduncles, decussating and ending in the rubrum (red nucleus)
and lateral nucleus of thalamus, is thence directly projected by new axones to the
sonuesthetic cortical area, or indirectly projected via thalamus (lateral nucleus).
Connections of the Striatum. — The connections of the caudatum and lenticula
with each other and with the cortex may be summarized as follows :
(a) Fibres from the cortex to caudatum and lenticula, entering into the forma-
tion of the corona radiata.
CENTRIFUGAL FIBRE
TERMINATING IN BULB
OLFACTORY
GLOMEHULI
OLFACTORY
MUCOSA
FIG. 634. — Schema of the olfactory bulb and tract neurones.
(6) Fibres from the caudatum and putamen of lenticula coursing to the thalamus
and hypothalamic region. Those from the caudatum pass through the internal
capsule to traverse the pallidum, are joined by the fibres from the putamen to
again traverse the internal capsule and end in the thalamus, forming the striato-
thalamic radiation.
(c) Fibres coursing ventrad in the medullary laminse of the lenticula, and re-
enforced by additional fibres from the pallidum, course mesad to the hypothalamic
region to form the subthalamic radiation or ansa lenticularis (described on p. 957).
This radiation is further reenforced by the ventral stalk of the thalamo-cortical
radiation to form the ansa peduncularis (described on p. 957).
The Olfactory Pathways. 1. Peripheral Pathway. — Impressions from the
upper portion of the Schneiderian mucous membrane pass along the olfactory fila
(central processes of the intra-epithelial bipolar olfactory cells) to the glomeruli
olfactorii in the olfactory bulb (Fig. 634).
2. Central Pathway. — In the glomeruli the impression is transmitted to the
brush-like, dendritic endings of the mitral cells and brush-cells; the axones of
these cells carry the impression centrad to the gray masses of the olfactory tract,
trigonum olfactorium, preperforatum, and adjacent parts (Fig. 630). These
constitute the primary centres.
THE CEREBRAL HEMISPHERES 965
The primary centres are connected with secondary or cortical centres (hippo-
campus, gyrus dentatus, uncus) by the following tracts :
1. Lateral olfactory striae, from the olfactory trigone to the uncus, ending in
the gyrus ambiens and gyrus semilunaris (p. 935).
2. Axones from cells in the olfactory trigonal gray through the fornix to hippo-
campus.
3. Striae medialis (Lancisii) from the trigone into gyrus subcallosus around the
callosum to gyrus dentatus and hippocampus.
The amygdala is by some regarded a cortical centre to which impressions are
carried by the taenia semicircularis.
The fornix fibres arise from the pyramidal cells in the hippocampus and the
polymorphous cells of the dentate gyre. Some fibres traverse the median plane
as the fornicommissure to the opposite hippocampus; the remainder end in the
albicans gray nucleus or, in small part, are retroflexed as the stria medullaris
thalami to the habenal ganglion.
In the albicans impressions are transmitted to the cells of two nuclear masses;
from the medial nucleus arise axones constituting the fasciculus albicantis princeps,
each axone bifurcating and the diverging bundles forming, respectively, the
albicantiothalamic and the albicantiotegmental fasciculi (p. 916).
The stria medullaris thalami consists of the following bundles ending in the
habenal ganglion:
(a) Axones from hippocampus via fornix — the cortico-habenal tract ; (6) axones
from the hemiseptum and olfactory gray — the olfacto-habenal tract; (c) axones
from the thalamus to the habenal ganglion — the thalamo-habenal tract.
In the habenal ganglion axones arise which pass as a distinct bundle ventrad
through the tegmentum to the gray of the postperforatum (ganglion interpedun-
culare [intercrurale] of Gudden) — the fasciculus retroflexus of Meynert.
The primary olfactory centres of the two sides are connected by the pars
olfactoria of the precommissure , a bundle of fibres passing from side to side to
end in the tract, granular stratum, and glomerular layer of the bulb.
Further connections are established with the tuber, mid-brain, and even spinal
centres; one division has-been named the olfacto-mesencephalic tract (Wallenberg).
The cingulum or fornix periphericus is an arcuate association bundle, or
rather an arcuate series of short bundles which establishes the connections of the
rhinencephalon with the adjacent cortical areas. (See p. 962.)
Weight of the Brain. — The average jveight of the brain in the adult male is 1400
grams; that of the female 1250 grams. Among 1500 brains of males the brain-
weights ranged from 960 grams to over 1900 grams; the great majority of this
series ranged from 1250 grams to 1500 grams. The average weight in the new-
born is 400 grams in the male and 380 grams in the female. The weight is doubled
at the end of the first and trebled at the end of the fourth or fifth year, the female
brain growing less rapidly than the male brain. Brain-growth generally ceases
in the eighteenth or twentieth year, earlier in the female than the male. After the
sixtieth year the brain loses weight, at first slowly, but more rapidly in advanced
senescence. Other factors, besides age and sex, which influence brain-weight are
stature, body-weight, cranial form, and race. Persons of large stature average
heavier brains than those of short stature in absolute figures, but not relatively.
Brachycephalic persons average heavier brains than the dolichocephalic. A
most profound influence upon brain-weight appears to be exerted by racial differ-
ences. Representatives of the white race have heavier brains than those of the
other races, although data are not sufficient to make a positive statement. Thus
the few Eskimo brains that have been secured so far are notable for their size
and weight. The following table gives approximately accurate averages based
upon greater or lesser numbers of brain-weights:
966
THE NER VE SYSTEM
Males.
Females.
White race •
Japanese
Chinese .
Germans
Bohemians .
1425
1420
1420
1415
1395
1380
1375
1360
1365
1360
1390-1200
1330
1250
1185
1260
1290
1260
1260
1260
1255
1240
1250
1215
Scots
Swedes ,
Russians
English
Italians
French
Negroes, vari
Hawaiians
Papuans .
ous races
Australians
The intellectual status is in some way reflected in the mass and weight of the
brain. The average brain-weight of 100 men eminent in the professions, arts, and
sciences, with an average age of 62 years, was 1470 grams, exceeding the average
weight of the ordinary population of about the same age by more than 100 grams.
A further analysis shows that the brains of men devoted to the higher intellectual
occupations, such as the mathematical sciences, involving the most complex
mechanisms of the mind, those of men who have devised original lines of research
and those of forceful character are among the heaviest of all.
The brains of microcephalic idiots are far under the minimal size necessary for
mental integrity, which is about 1000 grams in the male and 900 grams in the
female. Certain idiotic individuals possess brains of normal size or even abnormally
large brains, but structural defects underlie these forms of idiocy
The whale, porpoise, dolphin, and elephant possess larger brains than man,
but relative to the size and weight of the body the human brain is proportionately
larger.
CORTICAL LOCALIZATION OF FUNCTION.
Patient researches conducted along clinico-pathologic, experimental, physiologic, and de-
velopmental lines have furnished us with a topographic map of the somsesthetic and sense
areas and, inferentially, of the association areas of the cerebral cortex. The somsesthetic and
sense areas constitute less than one-third of the cortical area, while the remainder is presumed
to be devoted to the elaboration of the higher mental activities manifested by abstract thought,
ideation, reasoning, and language. The acquisition of these specifically human mental attri-
butes has been the chief factor in bringing about the superior structure of the human brain, and
those cortical regions which were subjected to increased associations rose in functional dignity
and increased in size. With over nine billion functional nerve-cells in the human cerebral
cortex devoted to the mental processes and less than one-third of these concerned with emissary
and receptive functions, the intricacy and capacity of the human brain for the manifold registra-
tion of sensations and the numerous transformations that characterize man's mental process
far exceed that of any other animal.
The delineation of areas called motor, visual, auditory, etc., is not to be deemed as mathe-
matically accurate or sharply defined as the boundaries of a State, county, or township. The areas
rather shade off in a diffuse manner and the arbitrary demarcations employed in the appended
figures merely show the maximum concentration of those cortical parts which most distinctly
appertain to the function alleged for them.
The principal areas that are known to be functionally differentiated are the following:
1 . Motor Area. — The motor area comprises the precentral gyre and parts of the frontal gyres
adjacent thereto, together with the paracentral gyre and the adjacent portion of the superfrontal
gyre on its mesal face. Stimulation of various parts of this area causes movement, while their
destruction impairs or abolishes voluntary movements. Within this motor area may be defined
districts which are cortical projections of the muscular systems of the body. Thus, movements
of the lower limb seem to be controlled by the dorsal part of the precentral and the paracentral
967
gvro: the trunk musculature by the area lying frontad both on the mesal aspect and in the dorsal
sujHTtVoiital; the upper limb seems to be controlled by the mid-portion of the precentral; while
the facial musculature is projected in the ventral part. The motor regions for the tongue,
FIG. 635. — Mesal view of left hemi cerebrum, showing localization of functions. The schema
of the fissures and gyres is the same as in Fig. 601.
larynx, muscles of mastication, and pharynx lie in the frontal opercular part; and the movement
of the head and eye are dominated by the medifrontal gyre, adjacent to the precentral. Re-
calling the fact that the pyramidal (motor) tract decussates in its course to the primary motor
FIG. 636. — Lateral view of left hemicerebrum, showing localization of functions. The schema
of the fissures and gyres is the same as in Fig. 600.
centres, it follows that the motor centres in one hemicerebrum control the movements of the
opposite side of the body. As elsewhere in the cortex, these motor areas gradually pass one into
the other and the boundaries are indeterminate. The localization of motor function is rather
968
THE NER VE SYSTEM
for coordinated groups of muscles than for individual muscles; as a rule the most powerful
articulation, as the thigh and the shoulder, is localizable frontad in the respective limb centres,
while the smaller articulations and those more differentiated as regards motility (digits, etc.)
are localizable more posteriorly.
2. Sensor Areas. — (a) The area for tactile and temperature impressions is more
intensely localized in the postcentral gyre and in corresponding order with its neighboring pre-
central motor areas; that is to say, there is the most intimate intercommunication between the
sensor and the motor regions which preside over corresponding parts of the body. So closely
coupled are the related sensor and motor cells in the highest category of the reflex arc system
represented in the cerebral cortex that both sensor and motor areas are included under the
term of somaesthetic or senso-motor area, devoted to the registration of cutaneous impressions,
impressions from the muscles, tendons, and joints; in short, the sense of movement. The cortical
area embraced by the parietal gyre, together with its extension in the precuneus on the mesal
aspect, appears to be devoted to the concrete perception of the form and solidity of objects and
is therefore termed the stereognostic sense area.
(6) The auditory area is localized in the middle third of the supertemporal gyre and in the
adjacent transtemporal gyres in the sylvian cleft.
FIG. 637. — Diagram showing the language zone. The opercula are divaricated to expose the insula.
(c) The visual area is most intensely localizable in the region of the calcarine fissure as well
as in the cuneus as a whole. There seems to be an interrelation between the visual function and
the special type of cortex already described, and chiefly characterized by the stripe of Gennari.
(d) The olfactory area comprises the uncus, frontal part of hippocampus, indusium, sub-
callosal gyre, parolfactory area, and preperforatum.
(e) The gustatory area has not yet been accurately localized; presumably it lies in the neigh-
borhood of the olfactory area in the temporal lobe (uncinate and hippocampal gyre?).
3. The Language Areas. — The cortical zone of language comprises certain specialized areas
which take part in the intimate relations of speech to thought-expression, to memory, in its
reading form to sight, in writing to manual muscular innervation, and in "word-understanding"
to hearing.
(a) The emissive (articular] centre for speech is localized in the region of the junction of the
subfrontal gyre with the precentral gyre — a region known to be intimately related to the control
of the muscles used in speech (larynx, tongue, jaw muscles). Destruction of this region at least
causes a loss or disturbance of articulation of words.
(6) The auditory receptive centre, clinically known as the centre of "word-deafness," is
localized in the marginal gyre and adjacent part of supertemporal gyre. A patient suffering with
a lesion of this area may clearly hear but not understand the spoken word. The centre might
also be called the lalognostic (word-understanding) centre.
(c) The visual receptive centre, clinically known as the centre of "word-blindness," is
CORTICAL LOCALIZATION OF FUNCTION
969
localized in rlu- angular gyre.- Lesions of this area renders the patient incapable of understand-
ing the significance of the words and objects which he sees.
(d) An emissive "writing" centre, not positively proven to exist, has been localized in the
medifrontal gyre, frontad of the motor area for the upper limb.
(e) Of not a little importance with reference to the intellectual control of the faculty of language
is the insula, purely an association centre, serving to connect the various receptive sense-areas
relating to the understanding of the written and spoken word with the somgesthetic emissary
centres related to articulate speech and writing.
The union of the various centres enumerated above forms the cortical zone of language
and is most intensely, if not exclusively, localized in the left hemicerebrum in right-handed
persons, and vice versa in left-handed persons.
FIG. 638. — Drawing to illustrate cranio-cerebral topography. (Taken from a cast in the Museum of the Royal
College of Surgeons of England, prepared by Professor Cunningham.)
4. The Association Areas. — The remaining area of the cerebral cortex is presumably the
organic substratum for the higher psychic activities. At the present time not much is known about
them, but broadly stated the frontal association area is concerned rather with the powers of
thought in the abstract; creative, constructive, and philosophic. The parieto-occipito-temporal
association area, on the other hand, seems to be concerned more with the powers of conception
of the concrete, for the comprehension of analogies, comparing, generalizing, and systematizing
things heard, observed, and felt.
The great extent of the association areas in the human brain is a somatic expression of man's
possession of an associative memory or ability to register and compare sensations far greater than
that of the highest ape. The pattern of the fissures and gyres in the brains of the higher anthro-
poids and man present the same general features in all these types. In the course of evolution,
however, the regions known as association areas assumed a greater energy of growth and ex-
panded in proportion to the rise in functional dignity of these areas. They are regions of "un-
stable equilibrium" which afford greater and more complex associations as mental development
970
THE NER VE SYSTEM
goes on in the species, and concomitant with this great cortical • expansion the associating or
coordinating fibre systems became more elaborate, complex, and far-reaching.
With the aid of the microscope the maturing of the brain-elements can be followed from the
earliest stages of embryonic life to the adult period. The Flechsig method has shown how the
function of nerve-fibres within the brain is only established when the myelin-sheath has developed.
But this development of mature nerve-fibres does not occur simultaneously throughout the brain]
but step by step in a definite order of succession: equally important bundles are myelinated'
simultaneously, but those of dissimilar importance develop one after another in accordance
with Flechsig's law. The successive myelinization of fibre-bundles to and from the cerebral
cortex corresponds to the successive awakenings of mental activities and faculties in the growing
child. Flechsig's method of investigation has been of great service in the elucidation of the
problems of cerebral localization.
Cranio-cerebral Topography.— The position of the principal fissures and convolution of the
cerebrum and their relation to the outer surface of the scalp (Fig. 638) have been the subject of
much investigation, and many systems have been devised by which one may localize these parts
from an explanation of the external surface of the head.
FIG. 639. — Relations of the principal fissures and convolutions of the cerebrum to the outer surface of
the scalp. (Reid.)
These plans can only be regarded as approximately correct for several reasons; in the first
place, because the relations of the convolutions and fissures to the surface are found to be quite
variable in different individuals; secondly, because the surface area of the scalp is greater than
the surface area of the brain, so that lines drawn on the one cannot correspond exactly to fissures
or convolutions on the other; thirdly, because the fissures and convolutions in two individuals
are never precisely alike. Nevertheless, the principal fissures and convolutions can be mapped
out with sufficient accuracy for all practical purposes, so that any particular convolution can be
generally exposed by removing with the trephine a certain portion of the skull's area. An
excellent method is given by Chipault in his Chirurgie operatoire du syst^me nerveux, 1894, vol. i.
The following systems have been the longest in vogue.
The various landmarks on the outside of the skull, which can be easily felt, and which serve
as indications of the position of the parts beneath, have been already referred to, and the rela-
tion of the fissures and convolutions to these landmarks is as follows :
Intercerebral or Longitudinal Fissure (Fig. 639). — This corresponds to a line drawn from
the glabella at the root of the nose to the external occipital protuberance.
The Sylvian Fissure (Fig. 639). — The position of the sylvian fissure is marked by a line starting
from a point 3 cm. horizontally behind the external angular process of the frontal bone to a point
2 cm. below the most prominent point of the parietal eminence. The first 2 cm. will represent the
basisylvian fissure, the remainder the sylvian fissure proper. The sylvian point is therefore
971
5 cm. behind and about 1 cm. above the level of the external angular process. The presylvian
nunus of the fissure passes upward from this point parallel to, and immediately behind, the
coronal suture.
The Tentorial Hiatus or Transverse Fissure.— This is between the cerebrum and cerebellum
and corresponds to a line drawn from the inion to the external auditory meatus (the line B C in
Fig. 639).
Central Fissure. — To find the dorsal end of the central fissure, a measurement should be taken
from the glabella to the external occipital protuberance. The position of the top of the fissure
will be, measuring from in front, 55.6 per cent, of the whole distance from the glabella to the
external occipital protuberance. Professor Thane adopts a somewhat simpler method. He
divides the distance from the glabella to the external occipital protuberance over the top of the
Supra orbital line /**
(Superior Horizontal} K/^a
B
S
K'
Orbital-auricular line
(Baseline)
z
FIG. 640. — Kronlein's method for determining the portions of certain fissures of the brain.
head into two equal parts, and, having thus defined the middle point of the vertex, he takes a point
half an inch behind it as the top of the sulcus. This is not quite so accurate as the former method ;
but it is sufficiently so for all practical purposes, and on account of its simplicity is very generally
adopted. From this point the fissure runs downward and forward for 9 to 10 cm., its axis making
an angle of 67 degrees with the middle line. Cunningham states that this angle more nearly averages
71 .5 degrees. In order to mark this groove, two strips of metal may be employed — one, the shorter,
being fixed to the middle of the other at the angle mentioned. If the longer strip is now placed
along the sagittal suture so that the junction of the two strips is over the point corresponding to
the top of the furrow, the shorter, oblique strip will indicate the direction and 9 to 10 cm. will
mark the length of the furrow. Dr. Wilson has devised an instrument, called a cyrtometer,
which combines the scale of measurements for localizing the fissure with data for representing
972 THE NERVE SYSTEM
its length and direction.1 Professor Thane gives the lower end of the furrow as close to the
sylvian fissure, and about 1.5 cm. behind the sylvian point. So that, according to this anatomist,
a line drawn from a point 1.5 cm. behind the mid-point between the glabella and external occipital
protuberance to this spot would mark out the central fissure. Dr. Reid adopts a different method
(Fig. 639). He first indicates on the surface the longitudinal fissure and the sylvian fissure
(as above). He then draws two perpendicular lines from his "base-line" (that is, a line from
the lowest part of the infraorbital margin through the middle of the external auditory meatus
to the back of the head) to the top of the cranium, one (D E, Fig. 639) from the depression in
front of the external auditory meatus, and the other (F G, Fig. 639) from the posterior border
of the mastoid process at its root. He has thus described on the surface of the head a four-sided
figure (F D GE, Fig. 639), and a diagonal line from the posterior superior angle to the anterior
perpendicular line where it is crossed by the sylvian fissure will represent the furrow.
The Occipital Fissure on the dorsal surface of the cerebrum runs outward at right angles to the
great longitudinal fissure for about 2 to 3 cm., from a point 0.5 cm. in front of the lambda (poste-
rior fontanelle). Reid states that if the sylvian fissure be continued onward to the sagittal
suture, the last 2 to 3 cm. of this line will indicate the position of the fissure (Fig. 639).
The Precentral SulcilS begins 2 cm. in front of the middle of the central fissure and extends
nearly, but not quite, to the sylvian fissure.
The Superfrontal Fissure runs backward from the supraorbital notch, parallel with the line
of the longitudinal fissure to 1 cm. in front of the line indicating the position of the central fissure.
The Subfrontal Fissure follows the course of the supertemporal ridge on the frontal bone.
The Intraparietal Fissure, comprising the parietal, subcentral and paroccipital fissures, begins
on a level with the junction of the middle and lower third of the central fissure, on a line carried
across the head from the back of the root of one auricle to that of the other. After passing upward
it curves backward, lying parallel to the longitudinal fissure, midway between it and the parietal
eminence; then curves downward to end midway between the posterior fontanelle and the
parietal eminence.
Kronlein's method for determining the portions of certain fissures of the brain is very useful
and easy of application (Fig. 640). It is as follows: (1) The base line, Z M , is a horizontal
line running at the level of the lower border of the orbit and the upper border of the external
auditory meatus. (2) Another horizontal line, K K', is drawn parallel to Z M. The second
horizontal line is on a level with the supraorbital ridge. (3) A vertical line, Z K, is erected
from Z M at the middle of the zygoma and is carried to the line, K Kf. (4) Another vertical line,
A R, is erected from the base-line at the level of the articulation of the mandible and is carried
to R. (5) A third vertical line, M P, is erected from the base-line at the posterior border of the
mastoid process and is carried to the middle line of the skull, which is marked P. (6) A line is
drawn from K to P. The portion of this line between R and P' corresponds to the central
fissure. (7) The angle P K K' is bisected by the line K S. K S corresponds to the sylvian
fissure, and K is directly over the sylvian point. To reach the anterior branch of the middle
meningeal, apply the trephine at K ; to reach the posterior branch, apply it at K'. In abscess
of the temporal lobe the trephine should be applied, according to von Bergmann, in the region
Aa K M.
THE MENINGES OR MENINGEAL MEMBRANES OF THE BRAIN
(MENINGES ENCEPHALI).
Dissection. — To examine the brain with its membranes, the skull-cap must be removed.
In order to effect this, saw through the external table, the section commencing, in front, about
2 cm. (1 in.) above the margin of the orbit, and extending, behind, to a little above the level with
the occipital protuberance. Then break the internal table with the chisel and hammer, to a void
injuring the investing membranes or brain; loosen and forcibly detach the skull-cap, and dura
will be exposed. The adhesion between the bone and the dura is very intimate, and much more
so in the young subject than in the adult.
The membranes of the brain are from without inward : the dura, arachnoid, and
the pia.
The Dura of the Brain (Dura Mater Encephali) (Figs. 641, 642, 643, 644).
The dura of the brain is a thick and dense, inelastic, fibrous membrane which
lines the interior of the skull. It is a covering for the brain and is also the internal
1 Lancet, 1888, vol. i, p 408.
THE DURA OF THE BRAIN 973
periosteum. Its outer surface is rough and fibrillated, and adheres closely to the
inner surface of the bones by fibrous processes and blood-vessels. The adhesion is
most marked on bony projections, opposite the sutures, and at the base of the skull.
Except at the sutures the adhesions are not dense, and between the fibrous pro-
cesses which pass to the bone are spaces which are thought to be lymph-spaces, and
are called epidural spaces. At these points the outer surface of the dura is covered
with endothelium. Fibrous tissue passes through the open sutures and joins the
outer layer of the dura to the external periosteum. It is known as the sutural mem-
brane. The inner surface of the dura limits the subdural space. It is smooth and
lined by a layer of endothelium. The dura sends four processes inward, into the
cavity of the skull, for the support and protection of the different parts of the brain,
and is prolonged to the outer surface of the skull through the various foramina
which exist at the base, and thus becomes continuous with the pericranium; its
fibrous layer forms sheaths for the nerves which pass through these apertures. At
the base of the skull it sends a fibrous prolongation into the foramen csecum; it
sends a series of tubular prolongations around the filaments of the olfactory nerves
as they pass through the cribriform plate, and also around the nasal nerve as it
passes through the nasal slit; a prolongation is also continued through the sphe-
noidal fissure into the orbit, and another is continued into the same cavity through
the optic foramen, forming a sheath for the optic nerve, where it is continued as far
as the eyeball. In the posterior fossa it sends a process into the internal auditory
ENDOSTCAL
LAYER
MENINGEAL
LAYER
ENDOTHELIAL
LINING
FIG. 641. — The structure of the dura. Section through the cranial vault of a child, slightly enlarged.
(Poirier and Charpy.)
meatus, ensheathing the facial and auditory nerves; another through the jugular
foramen, forming a sheath for the structures which pass through this opening; and
a third through the anterior condyloid foramen. Around the margin of the foramen
magnum it is closely adherent to the bone, and is continuous with the dura lining
the spinal canal. The cavity or cave of Meckel (cavum Meckeli] (Fig. 641) is an
osteo-fibrous recess near the apex of the petrous portion of the temporal bone,
formed by folding of the dura in a bony depression. It contains the Gasserian
ganglion. In certain situations, as already mentioned (p. 736), the fibrous layers
of-this membrane separate to form sinuses for the passage of venous blood. Upon
the outer surface of the dura, in the situation of the longitudinal sinus, may be seen
numerous small, whitish bodies, the arachnoid villi (p. 979).
Structure (Fig. 641). — The dura consists of white fibrous tissue with connective-
tissue cells and elastic fibres arranged in flattened laminse, which are imperfectly
separated by lacunar spaces and blood-vessels into two layers, endosteal and
meningeal. The endosteal layer is the internal periosteum for the cranial bones and
contains the bloodvessels for their supply. At the margin of the foramen magnum
it becomes continuous with the periosteum lining the spinal canal. The meningeal
or supporting layer is lined on its inner surface by a layer of nucleated endothelium,
similar to that found on serous membranes. By its reduplication the meningeal
layer forms the falx, the tentorium and falcula, and the diaphragma sellae. The two
layers are connected by fibers which intersect each other obliquely.
974
THE NER VE SYSTEM
The Arteries of the Dura (see section on Arteries). — The arteries of the dura
are very numerous, but are chiefly distributed to the bones. Those found in the
anterior fossa are the predural branches of the anterior and posterior ethmoidal and
internal carotid, and a branch from the medidural or middle meningeal. In the middle
fossa are the medi- and parvidural branches of the internal maxillary, a branch from
the ascending pharyngeal, which enters the skull through the foramen lacerum
medium basis cranii, branches from the internal carotid, and a recurrent branch
from the lacrimal. In the posterior fossa are dural branches from the occipital, one
of which enters the skull through the jugular foramen, and the other through the
mastoid foramen; the postdural or posterior meningeal, from the vertebral; occa-
sionally dural branches from the ascending pharyngeal, which enter the skull, one at
the jugular foramen, the other at the anterior condyloid foramen, and a branch
from the medidural.
The Veins of the Dura. — The veins which return the blood from the dura (see
p. 734), and partly from the bones, anastomose with the diploic veins (see p. 733).
These vessels terminate in the various sinuses, with the exception of two which
accompany the medidural artery, and pass out of the skull at the foramen spinosum
SUPERIOR LONGI-
TUDINAL SINUS
TENTORIUM
FIG. 642. — Crucial prolongation of the dura. Frontal section passing through the tentorium. The torcular
is seen in the centre. (Poirier and Charpy.)
to join the internal maxillary vein ; above, the dural veins communicate with the
superior longitudinal sinus. The sinuses are considered on pages 736 to 743
inclusive. On either side of the superior longitudinal sinus, especially near its
middle, and also near the lateral and straight sinuses, are numerous spaces in the
dura which communicate with the sinus, either by a small opening or a distinct
venous channel. These spaces are the parasinoidal sinuses (lacunce laterales) (Fig.
642). Many of the dural veins do not open directly into the sinuses, but indirectly
through the parasinoidal sinuses. These venous lacunae are often invaginated by
arachnoid villi, and they communicate with the underlying cerebral veins, and
also with the diploic and emissary veins.
The Lymphatics of the Dura. — The existence of lymphatic vessels is not proved.
Some anatomists claim to have injected such vessels along the middle meningeal
arteries (Mascagni, Arnold). Perivascular lymph-spaces do exist.
The Nerves of the Dura. — The nerves of the dura are filaments from the trochlear,
the ophthalmic division of the trigeminal, the semilunar or Gasserian ganglion, the
vagus, the hypoglossal, and the sympathetic.
THE DURA OF THE BRAIN
975
Processes of the Dura (processus durae matris). — The processes of the dura
sent inward into the cavity of the skull, are four in number: the falx, the tento-
rium, the falcula, and the diaphragma sellse.
The Falx (Figs. 642 and 644). — The falx or falx cerebri, so named from its
sickle-like form, is a strong arched process of the dura, which descends vertically
in the intercerebral fissure between the two hemispheres of the brain. It is narrow
in front, where it is attached to the crista galli of the ethmoid bone, and broad
behind, where it is connected with the upper surface of the tentorium. Its upper
margin is convex, and attached to the inner surface of the skull, in the middle line,
as far back as the internal occipital protuberance; it contains the superior or great
longitudinal sinus (sinus sagittalis superior}. Its lower margin is free, concave, and
presents a sharp, curved edge, which contains the falcial or inferior longitudinal sinus
DIAPHRAGMA SCLLAE
ANTERIOR
CLINOID
PROCESS
TENTORIUM
TORCULAR
FIG. 643. — The tentorium. (Poirier and Charpy.)
(sinus sagittalis inferior). The tentorial or straight sinus (sinus rectus) is formed
by the attachment of the falx to the tentorium.
The Tentorium (Figs. 642, 643, and 644). — The tentorium is an arched lamina
of dura, elevated in the middle and slightly inclined toward the circumference.
It intervenes between the upper surface of the cerebellum and the occipital lobes of
the cerebrum. It is attached, behind, by its convex border to the transverse ridges
upon the inner surface of the occipital bone, and there encloses on each side the
transverse or lateral sinus (sinus transversus) ; frontad, to the superior margin of
the petrous portion of the temporal bone on either side, there enclosing the super-
petrosal sinus (sinus petrosus superior) ; and at the apex of this bone the free or
internal border and the attached or external border meet, and, crossing one another,
are continued forward, to be attached to the anterior and posterior clinoid processes
respectively. Along the middle line of its upper surface the posterior border of the
976
THE NER VE SYSTEM
falx is attached, the tentorial or straight sinus being placed at their point of junction.
Its frontal border is free and concave, and with the dorsum sella? forms a large
oval opening. This opening is called the incisura tentorii and transmits the mes-
encephalon.
The Falcula (Fig. 642). — The falcula is a small triangular process of dura
received into the indentation between the two lateral lobes of the cerebellum
behind. Its base is attached, above, to the under and back part of the tentorium;
its posterior margin, to the lower division of the vertical crest on the inner surface
of the occipital bone. As it descends it sometimes divides into two smaller folds,
which are lost on the sides of the foramen magnum.
.INTERNAL JUGULAR
VEIN
FIG. 644. — Falx and tentorium, left lateral view. (Testut.)
The Diaphragma Sell® (Fig. 643). — The diaphragma sellse is a horizontal pro-
cess formed by a reduplication of the meningeal layer of the dura. It forms a small
circular fold, which constitutes a roof for the sella turcica. This almost completely
covers the hypophysis, presenting merely a small central opening (foramen
diaphragmatis sellae) for the passage of the infundibulum.
The Arachnoid (Arachnoidea Encephali) (Fig. 645).
The term arachnoid is from the Greek apdyvir] elooc, like a spider's web,
so named for its extreme thinness. The cranial arachnoid is a delicate mem-
brane which envelops the brain, lying between the pia internally and the dura
externally; from this latter membrane it is separated by a very fine slit or space,
the subdural space (cavum subdurale). The subdural space contains a very minute
quantity of fluid of the nature of lymph. This fluid obtains exit by way of the
THE ARACHNOID
977
parasinoidal sinuses. The sulxlural space is prolonged upon emerging nerves and
joins the lymph spaces of the nerves. The subdural space does not communicate
with the subarachnoid space.
The arachnoid invests the brain loosely, being separated from direct contact
with the cerebral substance by the pia, and a quantity of loose areolar tissue, the
subarachnoidean areolar tissue. On the upper surface of the cerebrum the arachnoid
is thin and transparent, and may be easily demonstrated by injecting a stream of
air beneath it by means of a blowpipe; it passes over the convolutions without
dipping down into the fissures between them, but does pass into the sylvian and inter-
cerebral fissures and is prolonged upon the nerves as a sheath. At the base of the
OLFACTORY
NERVE
VERTEBRAL
ARTERY
SPINAL
ARACHNOID
FIG. 645. — The arachnoid upon the base of the brain. On the right the arachnoid has been partly removed
to show the cerebrum and cerebellum with their superficial veins. (Poirier and Charpy.)
brain the arachnoid is thicker, and slightly opaque toward the central part; it
covers the orbital surface of the anterior lobes, and extends across between the
two temporal lobes so as to leave a considerable interval between it and the brain,
the cisterna basalis.
The Subarachnoid Space (cavum subarachnoideale] (Fig. 646). — The subarach-
noid space is the interval between the arachnoid and pia. It is not only on the
surface, but dips between the convolutions. It is not, properly speaking, a
space, for it is occupied everywhere by a spongy tissue consisting of trabeculae
of delicate connective tissue covered with endothelium, which pass from the pia
to the arachnoid, and in the meshes of which the subarachnoid fluid is contained.
62
978 THE NERVE SYSTEM
This so-called space is small on the surface of the cerebrum; but at the base of
the brain the subarachnoid tissue is less abundant and its meshes larger.
In certain regions the arachnoid and pia are farther apart than was previously
indicated, and these spaces are called subarachnoid cisternae (cisternae subarach-
noidalis). The largest space is the continuation of the posterior part of the sub-
arachnoid space of the spinal cord. It is called the postcisterna (cisterna cere-
bellomedullaris}. It is a space formed by the arachnoid passing across the back
and under portions of the oblongata and cerebellum. It communicates with the
fourth ventricle by three foramina. The largest opening is the metapore or
foramen of Majendie (apertura medialis ventriculi quarti). It is in the middle line
of the metatela. At the end of each recessus lateralis of the fourth ventricle
there is also an opening, and each opening is called the foramen of Luschka or
of Key and Retzius (apertura lateralis ventriculi quarti). The cisterna pontis is
the continuation upward of the anterior part of the subarachnoid space of the
cord. About the oblongata it is continuous with the postcisterna, so this important
nerve-centre is surrounded by a large subarachnoid space. The crural cisterna or
cisterna basalis (cisterna interpeduncularis) is formed by the arachnoid extending
between the two temporal lobes, and contains the arteries forming the circulus.
ARACHNOID
PIA
CONVOLUTION
OF CEREBRUM
FIG. 646. — The subarachnoid space. (Schematic.) (Poirier and Charpy.)
The anterior subarachnoid space (cisterna pontis, inter peduncular is et chiasmatis)
includes the cisterna pontis, the cisterna basalis, and the cisterna of the chiasm.
There is a cisterna between the inferior edge of the falx and the superior surface
of the callosum which contains the precerebral arteries, a cisterna in the sylvian
fissure (cisterna sylviana) which contains the precerebral artery, and a cisterna
between the quadrigemina which contains the vena magna Galeni.
The cerebro-spinal fluid (coeliolympha; liquor cerebrospinalis) fills the sub-
arachnoid space. It is a clear, limpid fluid, having a saltish taste and a slightly
alkaline reaction. According to Lassaigne, it consists of 98.5 parts of water,
the remaining 1.5 per cent, being solid matters, animal and saline. It varies in.
quantity, being most abundant in old persons, and is quickly reproduced. Its
chief use is probably to afford mechanical protection to the nervous centres, and
to prevent the effects of concussions communicated from without.
Structure. — The arachnoid consists of bundles of connective tissue, the fine
fibres of which form one layer and cross each other in every direction. At the
level of the large fissures, and especially around the circulus, it is reenforced
by thick fibrous tissue. Both surfaces are covered with endothelium. There
are no blood-vessels in the arachnoid; the vessels which appear to be in it are
really in the pia. There is no positive proof that nerves are present in the
THE ARACHNOID VILLI OR PAGGHIONIAN BODIES 979
arachnoid. It is true that Bochdalek and Luschka long ago described arachnoid
nerves, but these observations have never been corroborated.
The Arachnoid Villi or Pacchionian Bodies (Granulationes Arachnoideales).
The arachnoid villi, erroneously called glandulse Pacchioni, are numerous
small whitish or purplish projections, usually collected into clusters of variable
size, which are found in the following situations: (1) Upon the outer surface of the
dura, in the vicinity of the superior longitudinal sinus, being received into little
depressions on the inner surface of the calvarium. (2) On the inner surface of the
dura. (3) In the superior longitudinal sinus and the other sinuses.
A hasty examination would lead us to suppose that these bodies spring from
the dura, but, as a matter of fact, they originate from the arachnoid. They are
not glandular in structure, but are simply enlarged normal villi of the arachnoid.
In their growth they appear to perforate the dura, and when a group of villi is of
JAUOATUM
it ::-i;"/mm^Jmm^r' ~ ~ M\
FORNICOLUMNS
VENA
OALENI
FIG. 647. — Velum. (Poirier and Charpy.)
large size it causes absorption of the bone, and comes to be lodged in a pit or
depression (foveola granularis [Pacchioni]} on the inner table of the skull.
Their manner of growth is as follows : At an early period they project through
minute holes in the inner layer of the dura, which open into large venous spaces
situated in the tissues of the membrane, on either side of the longitudinal sinus
and communicating with it. In their onward growth the villi push the outer
layer of the dura before them, and this forms over them a delicate membran-
ous sheath. In structure they consist of spongy trabecular tissue, covered over
by a membrane, which is continuous with the arachnoid. The space between
these two coverings, derived from the dura and arachnoid respectively, corre-
sponds to and is continuous with the subdural space. The spongy tissue of which
they are composed is continuous with the trabecular tissue of the subarachnoid
space; so that fluid injected into the subarachnoid space finds its way into
the Pacchionian bodies, and through their coverings filters into the superior
longitudinal sinus. They are supposed to be a means of getting rid of an
excess of cerebro-spinal fluid, when its quantity is increased above normal or
980
THE NERVE SYSTEM
for replenishing the cerebro-spinal fluid from the blood plasma when needed.
Another means of getting rid of cerebro-spinal fluid is absorption by the lymph-
spaces of the cranial nerves, which possess sheaths of arachnoid up to the 'points
at which they emerge from the skull.
These bodies are not found in infancy, and very rarely until the third year.
They are usually found after the tenth year; and from this period they increase
in number as age advances. Occasionally they are wanting.
FRONTAL
LOBE
MEDICERCBRAL
ARTERY
PRECHORO
ARTERY
PREGENICULUM
POSTGENICULUM
MEOICORNU
OF LATCRA
VENTRICLE
PRECCREBRAL
ARTERY
PRE-
COMMUNICANT
ARTERY
INTERNAL
CAROTID
POST-
COMMUNICANT
ARTERY
BASILAR
ARTERY
POST-
CEREBRAL
ARTERY
UADRIGEMINA
OCCIPITAL
• LOBE
FIG. 648. — The precerebral and choroid arteries. (Spalteholz.)
The Pia of the Brain (Pia Mater Encephali) (Figs. 646 and 647).
The pia of the brain is a vascular membrane, and derives its blood from the
internal carotid and vertebral arteries. It consists of a minute plexus of blood-
vessels, held together by an extremely fine areolar tissue. It invests the entire
surface of the brain, dipping down between the convolutions and laminse, and
is prolonged into the interior, forming the velum and the choroid plexuses of the
lateral and fourth ventricles.
THE PIA OF THE BRAIN
981
The Velum or the Tela Chorioidea Superior (tela chorioidca ventriculi tertii)
(Fig. 047). — The velum is the prolongation of the pia into the interior of the brain
through the medium of the transverse fissure. It is a double triangular vascular
fold, that lies between the body of the fornix above and the optic thalami and the
epithelial roof of the third ventricle below, and passes forward to the porta. At
each edge of the velum is the paraplexus or choroid plexus (plexus chorioideus
rentricnli lateral is) of the corresponding lateral ventricle. In front the two
plexuses join behind the porta, and at the point of junction two lesser choroid
plexuses pass back along the under surface of the velum to the third ventricle,
the diaplexus or median plexus (plexus chorioideus ventriculi tertii). The velar
veins or veins of Galen (p. 947) are two veins which lie on either side of the middle
of the velum and pass back. Each velar vein is formed by the union of the vein
from the striatum and the choroid vein from the choroid plexuses. The two velar
veins unite and form the vena magna (Galeni), which empties into the straight
sinus.
SUPERCALLOSAL
FISSURE
OCCIPITAL
PRECCREBRAL
ARTERY
OPTIC
NERVE
CALCARINE
FISSURE
PRECOMMUNI-
CANT. ARTERY
INTERNAL POSTCOMMUNI- POST-
CAROTID CANT ARTERY CEREBRAL
ARTERY ARTERY
FIG. 649. — The arteries of the medial surface of the right hemicerebrum. (Spalteholz.)
The pia of the surfaces of the hemispheres, where it covers the gray matter
of the convolutions, is very vascular, and gives off from its inner surface a multi-
tude of minute vessels, which extend perpendicularly for some distance into the
cerebral substance. At the base of the brain, in the situation of the pre- and post-
perforatum, a number of long, straight vessels are given off, which pass through
the white substance to reach the gray substance in the interior. On the cerebellum
the membrane is more delicate, and the vessels from its inner surface are shorter.
The pia of the spinal cord is thicker, firmer, and less vascular than that of the
brain, and as it is traced upward over the oblongata it is seen to preserve these
characters. At the upper border of the oblongata it is prolonged over the lower
half of the fourth ventricle, forming, before it is reflected on to the under surface
of the cerebellum, a covering for the fourth ventricle called the metatela or tela
chorioidea inferior (tela chorioidea ventriculi quarti) ; this carries the choroid plexus
of the fourth ventricle (plexus chorioideus ventriculi quarti).
982 THE NERVE SYSTEM
The arteries of the pia (see pp. 628, 629, and 630) (Figs. 648 and 649) are the
precerebrals, medicerebrals, postcerebrals, prechoroids, postchoroids, the precere-
bellars, medicerebellars, and postcerebellars. (The vessels of the cerebral ganglionic
system and of the cortical arterial system are considered on p. 632.)
The veins of the pia (see pp. 734, 735, and 736) are the basilar vein, the velar veins
(Fig. 647), the veins constituting the choroid plexuses of the third ventricle, the
lateral ventricles, and the fourth ventricle; the cerebral veins (Fig. 645) and the
cerebellar veins (Fig. 645).
The nerves of the pia accompany the branches of the arteries and are derived
chiefly from the sympathetic. A few fibres are derived from certain cranial
nerves, all of which are probably of the afferent variety.
THE SPINAL NERVES (NERVI SPINALES).
The spinal nerves are so called because they apparently originate from the spinal
cord, and are transmitted through the intervertebral foramina on either side of the
spinal column. There are thirty-one pairs of spinal nerves, which are arranged
into the following groups, corresponding to the region of the spine through which
they pass:
Cervical 8 pairs.
Thoracic . 12 "
Lumbar 5 "
; Sacral 5 •'
Coccygeal 1 pair.
It will be observed that each group of nerves corresponds in number with the
vertebrae in that region, except the cervical and coccygeal. Sometimes there is no
thirty-first pair. Occasionally below the thirty-first pair there may be one or even
two filamentous pairs which do not pass out of the vertebral canal.
Each spinal nerve arises by two roots, a ventral or motor root and a dorsal or
sensor root, the latter being distinguished by a ganglion termed the spinal ganglion.
The Roots of the Spinal Nerves (Figs. 540, 541, 650, 651, 652).
The Ventral Root (radix anterior}. — The superficial origin is from the ventro-
lateral columns of the corcl, corresponding to the situation of the ventral cornu of
gray matter. Each root is composed of from four to eight filaments.
The deep origin can be traced from cells in the gray substance of the ventral
cornu of the same as well as of the opposite side. The majority of the axones
arise from the various groups of cells in the ventral cornu of the same side,
while others arise from the large cells of the ventral cornu of the opposite side,
the axones passing across the median plane in the ventral white commissure.
The axone bundles, after leaving the gray substance, penetrate horizontally
through the longitudinal bundles of the ventro-lateral column to emerge as
described above.
The Dorsal Root (radix posterior}. — The superficial origin is by filaments (fila
radicularia} , from the dorso-lateral fissure of the cord. The real origin of these
fibres is from the nerve-cells in the dorsal-root ganglion, from which they can be
traced into the cord in two main bundles, the course of which has already been
studied (p. 849).
The ventral roots are smaller than the dorsal, devoid of ganglionic enlargement,
THE GANGLIA OF THE SPINAL NERVES
983
and their component fibrils are collected into two bundles near the intervertebr;:!
foramina.
The dorsal roots of the nerves are larger, but the individual filaments are finer and
more delicate than those of the ventral. The cells of the ganglion upon each
dorsal root give rise to central and peripheral processes; the central processes
constitute the dorsal roots, the peripheral processes are modified dendrites
(p. 827) which join the ventral efferent axones and form the spinal nerve trunk
ensheathed by a tubular process of the dura and pia.
The dorsal root of the first cervical nerve forms an exception to these characters.
It is smaller than the ventral, has occasionally no ganglion developed upon it, and
when the ganglion exists it is often situated within the dura. The first cervical
may have a rudimentary dorsal root or no dorsal root.
Within the vertebral canal the nerve-roots are separated from each other by the
ligamentum denticulatum (Fig. 651). In the cervical region the spinal portion of
the accessory nerve separates the roots.
Each root obtains a covering of pia,
which becomes continuous with the neuri-
lemma; "the arachnoid invests each root
as far as the point where it meets with the
dura; the two roots, after piercing the
dura separately, are enclosed by it in a
single tubular sheath, in which is included
the spinal ganglion of the dorsal root."
(Cunningham.)
DORSAL
NERVE '
ROOTS )
DORSAL
ROOTS
I VENTRAL
•\ NERVE
(. ROOTS
LIGAMENTUM
,DENTICULATUM
DURA
..VENTRAL
ROOTS
SPINAL NERVE
IN ITS RIAL
SHEATH
LIGAMENTUM
DENTICULATUM
VENTRAL ROOTS
The Ganglia of the Spinal Nerves (Gan-
glia Spinales) (Figs. 650, 651, 652).
A ganglion is developed upon the dorsal
root of each of the spinal nerves. The
ganglion upon the dorsal root of the first
cervical nerve may be rudimentary or
absent. These ganglia are of an oval form
and of a reddish color; they bear a pro-
portion in size to the nerves upon which
they are formed, and are placed in the
intervertebral foramina, ectad of the point
where the nerves perforate the dura.
Each ganglion is bifid internally, where it
is joined by the two bundles of the dorsal
root, the two portions being united into a
single mass externally. The ganglia upon
the first and second cervical nerves form
an exception to these characters, being placed on the arches of the vertebra over
t which the nerves pass. The ganglia of the sacral nerves are placed within the verte-
bral canal; and that on the coceygeal nerve, also in the canal, is situated at some
distance from the origin of the dorsal root.
The ganglion in an embryo is composed of bipolar nerve-cells. In an adult the
bipolar nerve-cells by fusion of their two poles form unipolar elements. The
process of each unipolar cell divides into two a short distance from the cell. One
of the processes from each cell passes to the spinal cord, and the other passes into
the spinal nerve. On the dorsal roots of the lumbar and sacral nerves, between
the spinal ganglia and the cord, small cellular masses occasionally exist. They are
called accessory or aberrant ganglia (ganglia aberrantia}.
SPINAL NERVE
IN ITS SHEATH
FIG. 650.
portion of the spinal cord, showing
its right lateral surface. The dura is opened and
arranged to show the nerve-roots. (Testut.)
984
THE NERVE SYSTEM
Distribution of the Spinal Nerves.
Immediately beyond the ganglion the two roots coalesce, their fibres inter-
mingle, and the trunk thus formed constitutes the spinal nerve; it passes out of the
intervertebral foramen, and divides into a dorsal primary division for the supply of
the dorsal part of the body, and a ventral primary division for the supply of the
ventral part of the body (Fig. 651). Each division contains fibres from both roots.
NAL BRANCH
:XTERNALBriANCH
RSAL PRIMARY
DIVISION
S COMMUNICANS
FIG. 651. — Plan of the constitution of a spinal nerve. (W. Keiller, in Gerrish's Text-book of Anatomy.)
Before dividing, each spinal nerve gives off a small recurrent or meningeal
branch (ramus meningeus) (Fig. 651), which is joined by a filament from the com-
municating branch of the sympathetic (ramus communiccms) (Fig. 651), which con-
nects the ganglion with the ventral division. The meningeal branches unite and
form one nerve, which passes inward through the intervertebral foramen and
supplies the dura, sending branches to the vertebra? and vertebral ligaments.
Neuraxis of Peripheral
Sensor Neurone
Nerve Trunk !
Spinal Ganglion
Dendrite of
Peripheral Sensor
Neurone
Neuraxis of
Sympathetic Neurone
'Neuraxis of Peripheral Motor Neurone
jt
:f Sympathetic Ganglion
- FIG. 652. — Diagram to show the composition of a peripheral nerve-trunk. (Bohm and Davidoff.)
The Dorsal Primary Divisions (rami posteriores) (Fig. 631). — The dorsal primary
divisions of the spinal nerves are generally smaller than the ventral; they arise
from the trunk resulting from the union of the roots, in the intervertebral foramina;
and, passing dorsad, divide into internal and external branches, which are dis-
tributed to the muscles and integument behind the spine. The dorsal primary
divisions of the spinal nerves form two small plexuses, the dorsal cervical plexus
and the dorsal sacral plexus. The first cervical, the fourth and fifth sacral, and the
coccygeal nerves do not divide into external and internal branches.
POINTS OF EMERGENCE OF THE SPINAL NERVES
985
The Ventral Primary Divisions (rami anteriores) (Fig. 651). — The ventral primary
divisions of the spinal nerves supply the parts of the body ventrad of the spine,
including the limbs. They are for the most part larger than the dorsal primary
divisions. Each division, soon after its origin, receives a slender filament from the
.sympathetic, which is called the gray ramus communicans. In the thoracic region
the ventral primary divisions of the spinal nerves are quite separate from each
other, and are uniform in their distribution; but in thetervical, lumbar, and sacral
regions they form intricate plexuses previous to their distribution. The ventral
primary divisions of certain thoracic, lumbar, and sacral nerves give off a delicate
collection of nerve-filaments to the sympathetic cord. These are called the white
rami communicants s or the visceral branches of the spinal nerves.
Ventral aspect.
FIG. 653. — Distribution of cutaneous nerves.
Points of Emergence of the Spinal Nerves.
The roots of the spinal nerves from their origin in the cord run obliquely caudad
to their point of exit from the intervertebral foramina, the amount of obliquity
varying in different regions of the spine, and being greater in the lower than the
986 THE NER VE SYSTEM
upper part. The level of their emergence from the cord is within certain limits
variable, and of course does not correspond to the point of emergence of the nerve
from the intervertebral foramina (Fig. 653).
THE CERVICAL NERVES (NN. CERVICALES).
The Roots of the Cervical Nerves.
The roots of the cervical nerves increase in size from the first to the fifth, and then
remain the same size to the eighth. The dorsal roots bear a proportion to the
ventral as 3 to 1, which is much greater than in any other region, the individual
filaments being also much larger than those of the ventral roots. The dorsal root
of the first cervical is an exception to this rule; it is smaller than the ventral root.
In direction the roots of the cervical are less oblique than those of the other spinal
nerves. The first cervical nerve is directed a little cephalad and ectad; the
second is horizontal; the others are directed obliquely caudad and ectad, the
lowest being the most oblique, and consequently longer than the upper, the distance
between their place of origin and their point of exit from the vertebral canal never
exceeding the depth of one vertebra.
The First Cervical or Suboccipital Nerve (n. suboccipitalis] (Fig. 654).— The
dorsal root may be rudimentary or absent. The trunk of the first cervical nerve
leaves the vertebral canal between the occipital bone and the dorsal arch of the atlas
(Figs. 16 and 202).
The Trunk of the Second Cervical Nerve leaves the vertebral canal between the
dorsal arch of the atlas and the lamina of the axis; and the eighth (the last)
between the last cervical and first thoracic vertebrae.
Each nerve, at its exit from the intervertebral foramen, divides into a dorsal and
a ventral division. The ventral divisions of the four upper cervical nerves form the
cervical plexus. The ventral divisions of the four lower cervical nerves, together
with the first thoracic, form the brachial plexus.
The Dorsal Divisions of the Cervical Nerves (Kami Posteriores).
The Dorsal Division of the First Cervical Nerve (Fig. 654) differs from the dorsal
divisions of the other cervical nerves in not dividing into an internal and external
branch. It is larger than the ventral division, and escapes from the vertebral
canal between the occipital bone and the dorsal arch of the atlas, lying beneath the
vertebral artery. It enters the suboccipital triangle formed by the Rectus capitis
posticus major, the Obliquus superior and Obliquus inferior, and, by muscular
branches, supplies the Recti and Obliqui muscles, and the Complexus. From the
branch which supplies the Inferior oblique a communicating filament is given off
which joins the second cervical nerve. This nerve also occasionally gives off a
cutaneous filament, which accompanies the occipital artery and communicates-
with the occipitalis major and minor nerves.
The Dorsal Division of the Second Cervical Nerve is three or four times greater
in diameter than the ventral division, and the largest of all the dorsal cervical
divisions. It emerges from the vertebral canal between the dorsal arch of the atlas
and lamina of the axis, below the Inferior oblique. It supplies a twig to this
muscle, and receives a communicating filament from the first cervical. It then
divides into an internal and an external branch.
The internal branch called, from its size and distribution, the great occipital nerve
(occipitalis major] (Fig. 654), ascends obliquely inward between the Obliquus-
THE DORSAL DIVISIONS OF THE CERVICAL NERVES
987
inferior and Complexus, and pierces the latter muscle and the Trapezius near
their attachments to the cranium. It is now joined by a filament from the dorsal
division of the third cervical nerve, the anastomotic, and, ascending on the
back part of the head with the occipital artery, divides into two branches, which
supply the integument of the scalp as far forward as the vertex, communicating
with the occipitalis minor. It gives off an auricular branch to the back part of the
ear and muscular branches to the Complexus.
The external branch is often joined by the external branch of the dorsal division
of the third cervical nerve, and supplies the Splenius, Trachelo-mastoid, and
Complexus.
The Dorsal Division of the Third Cervical Nerve (Fig. 654) is smaller than the
preceding, but larger than the fourth; it differs from the dorsal divisions of the
remaining cervical nerves in its supplying an additional filament, the third occipital
nerve, to the integument of the occiput. The dorsal division of the third nerve, like
the others, divides into an internal and external branch.
GREAT OCCIPI-
TAL NERVE
RECTUS CAPITIS
LATERALIS
VENTRAL PRIMARY DIVI-
SION OF FIRST CERVICAL
OBLIQUUS
SUPERIOR
DORSAL PRIMARY DIVI-
SION OF FIRST CERVICALl
ICH TO COMPLEXUS — OUT
VERTEBRAL ARTERV
ORSAL PRIMARY DIVISION
OF FIRST CERVICAL
ANASTOMOTIC BRANCH
ANASTOMOTIC
THIRD CERVICAL
OBLIQUUS
INFERIOR
RECTUS
MAJOR
FIG. 654. — Dorsal primary divisions of the upper three cervical nerves. (Testut.)
The internal or cutaneous branch passes between the Complexus and Semispinalis,
and, piercing the Splenius and Trapezius, supplies the skin over the latter muscle.
The external branch joins with that of the dorsal division of the second to supply
the Splenius, Trachelo-mastoid, and Complexus.
The third or least occipital nerve (n. occipitalis minimus or n. occipitalis tertius)
(Fig. 654) arises from the internal or cutaneous branch of the dorsal division of
the third cervical nerve, beneath the Trapezius; it then pierces that muscle, and
supplies the skin on the lower and back part of the head. It lies to the inner side
of the occipitalis major, with which it is connected.
The dorsal division of the suboccipital nerve and the internal branches of the
dorsal divisions of the second and third cervical nerves are occasionally joined
beneath the Complexus by communicating branches. This communication is
described by Cruveilhier as the dorsal cervical plexus.
The Dorsal Divisions of the Fourth, Fifth, Sixth, Seventh, and Eighth Cervical
Nerves pass dorsad, and divide, behind the Intertransversales muscles, into internal
and external branches.
The internal branches, the larger, are distributed differently in the upper and
lower part of the neck. Those derived from the fourth and fifth nerves pass
between the Complexus and Semispinalis muscles, and, having reached the spinous
988 THE NERVE SYSTEM
processes, perforate the aponeurosis of the Splenius and Trapezius, and are con-
tinued outward to the integument over the Trapezius, whilst those derived from
the three lowest cervical nerves are the smallest, and are placed beneath the Semi-
spinalis colli, which they supply, and then pass into the Interspinalis, Multifidus
spinse, and Complexus, and send twigs through this latter muscle to supply the
integument near the spinous processes (Hirschfeld).
The external branches supply the muscles at the side of the neck — viz., the
Cervicalis ascendens, Transversalis colli, and Trachelo-mastoid.
The Ventral Divisions of the Cervical Nerves (Kami Anteriores).
The Ventral Division of the First Cervical Nerve (Fig. 656) is of small size. It
escapes from the vertebral canal through a groove upon the dorsal arch of the atlas.
In this groove it lies beneath the vertebral artery, to the inner side of the Rectus
capitis lateralis. As it crosses the foramen in the transverse process of the atlas it re
ceives a filament from the sympathetic. It then descends ventrad of the transverse
process, to communicate with an ascending branch from the second cervical nerve.
Communicating filaments from the loop between this nerve and the second cervi-
cal nerve join the vagus, the hypoglossal, and sympathetic, and some branches are
distributed to the Rectus lateralis and the two Anterior recti. The fibres which
communicate with the hypoglossal simply pass through the latter nerve to become
for the most part the descendens hypoglossi. According to Valentin, the ventral
division of the suboccipital nerve distributes filaments to the occipito-atlantal
articulation and to the mastoid process of the temporal bone.
The Ventral Division of the Second Cervical Nerve (Fig. 656) escapes from the
vertebral canal, between the dorsal arch of the atlas and the lamina of the axis, and,
passing forward on the outer side of the vertebral artery, divides ventrad of the
Intertransverse muscle into an ascending branch, which joins the first cervical; and
one or two descending branches, which join the third cervical. It gives off the small
occipital; a branch to assist in forming the great auricular; another to assist in
forming the superficial cervical; one of the communicantes hypoglossi, and a filament
to the Stern o-mastoid, which communicates in the substance of the muscle with
the spinal accessory.
The Ventral Division of the Third Cervical Nerve (Fig. 656) is double the size of
the preceding. At its exit from the intervertebral foramen it passes caudad and
outward beneath the Sterno-mastoid muscle, and divides into two branches. The
ascending branch joins the ventral division of the second cervical; the descending
branch passes down ventrad of the Scalenus anticus muscle and communicates with
the fourth cervical. It gives off the larger part of the great auricular and superficial
cervical nerves; one of the communicantes hypoglossi; a branch to the supraclavic-
ular nerves; a filament to assist in forming the phrenic; and muscular branches
to the Levator anguli scapulae and Trapezius; this latter nerve communicates
beneath the muscle with the accessory nerve. Sometimes the nerve to the Scalenus
medius is derived from this source.
The Ventral Division of the Fourth Cervical Nerve (Fig. 656) is of the same size as
the preceding. It receives a branch from the third, sends a communicating branch
to the fifth cervical, and, passing caudad and outward, divides into numerous
filaments, which cross the dorsal triangle of the neck, forming the supraclavicular
nerves. It gives a branch to the phrenic nerve, while it is contained in the inter-
transverse space, and sometimes a branch to the Scalenus medius muscle. It also
gives a branch to the I^evator anguli scapula? and to the Trapezius, which unites
with the branch given off from the third nerve, and communicates beneath the
muscle with the accessory nerve.
THE CERVICAL PLEXUS 989
The Ventral Divisions of the Fifth, Sixth, Seventh, and Eighth Cervical Nerves are
remarkable for their size. They are much larger than the preceding nerves, and
are all of equal dimensions. They assist in the formation of the brachial plexus.
The Cervical Plexus (Plexus Cervicalis) (Figs. 655 and 656).
The cervical plexus is formed by the ventral divisions of the four upper cervical
nerves. It is situated opposite the four upper cervical vertebrae, resting upon the
Levator anguli scapulae and Scalenus medius muscles, and covered in by the
Sterno-mastoid.
Its branches may be divided into two groups, superficial and deep, which may
be thus arranged:
( Occipitalis minor.
C Ascending . . < Auricularis magnus.
:Superficialis colli.
Superficial
C Suprasternal.
Descending . . Supraclavicular < Supraclavicular.
( Supra-acromial.
C Communicating.
/• T * i ) Muscular.
j Communicantes hypoglossi.
Deep . 1 [^ Phrenic.
Fxternal J Communicating.
' 1 Muscular.
The Superficial Branches of the Cervical Plexus. The Small Occipital Nerve
(n. occipitalis minor) (Fig. 655). — The small occipital nerve arises from the second
cervical nerve, sometimes also from the third; it curves round the dorsal border
of the Sterno-mastoid, and ascends, running parallel to the dorsal border of the
muscle, to the back part of the side of the head. Near the cranium it perforates
the deep fascia, and is continued cephalad along the side of the head behind the
ear, supplying the integument, and communicating with the occipitalis major,
auricularis magnus, and with the dorsal auricular branch of the facial.
This nerve gives off an auricular branch, which supplies the integument of the
upper and back part of the auricle, communicating with the mastoid branch
of the auricularis magnus. The auricular branch is occasionally derived from
the great occipital nerve. The occipitalis minor varies in size; it is occasionally
double.
The Great Auricular Nerve (n. auricularis magnus} (Fig. 655). — The great
auricular nerve is the largest of the ascending branches. It arises from the
second and third cervical nerves, winds around the dorsal border of the Sterno-
mastoid, and, after perforating the deep fascia, ascends upon that muscle beneath
the Platysma to the parotid gland, where it divides into facial, auricular, and
mastoid branches.
The Facial Branches pass across the parotid, and are distributed to the integ-
ument of the face over the parotid gland; others penetrate the substance of the
gland and communicate with the facial nerve.
The Auricular Branches ascend to supply the integument of the back of the
pinna, except at its upper part, communicating with the auricular branches of
the facial and vagus nerves. A filament pierces the pinna to reach its outer
surface, where it is distributed to the lobule and lower part of the concha.
990
THE NERVE SYSTEM
The Mastoid Branch communicates with the occipitalis minor and the dorsal
auricular branch of the facial, and is distributed to the integument behind the
ear.
The Superficial Cervical Nerve or the Superficialis Colli (n. cutaneus colli} (Fig.
655). — The superficial cervical nerve or the superficialis colli arises from the
second and third cervical nerves, turns around the dorsal border of the Sterno-
mastoid about its middle, and, passing obliquely forward beneath the external
jugular vein to the ventral border of the muscle, perforates the deep cervical
fascia, and divides beneath the Platysma into two branches, which are distributed
to the ventro-lateral parts of the neck.
DORSAL
AURICULAR
NERVE
GREAT
OCCIPITAL
GREAT
AURICULAR
(dorsal branch)
SMALL
OCCIPITAL
THIRD
OCCIPITAL
GREAT
AURICULAR
(ventral branches)
BRANCHES TO
TRAPEZIUS
SUPRACLAVICULAR
NERVES
(acromial
branches)
INFRAMANDIBULAR
BRANCH OF
FACIAL
SUPERFICIAL
CERVICAL
NERVES
BRANCHES
OF FACIAL
NERVE
SUPRACLAVICULAR
NERVES (sternal
branches)
SUPRACLAVICULAR
NERVES (clavicular
branches)
FIG. 655.— The cutaneous branches of the right cervical plexus, viewed from the right. The Platysma
has been partly removed. (Spalteholz.)
The Ascending Branch or Branches (rami superiores} gives a filament which
accompanies the external jugular vein; it then passes cephalad to the submaxillary
region, and divides into branches, some of which form a plexus with the cervical
branches of the facial nerve beneath the Platysma; others pierce that muscle
and are distributed to the integument of the upper half of the neck, at its forepart,
as high as the chin.
THE CERVICAL PLEXUS
991
The Descending Branches (rami inferior -es), usually represented by two or more
filaments, pierce the Platysma, and are distributed to the integument of the side
and front of the neck, as low as the sternum.
The Descending or Supraclavicular Branches (mi. supraclaviculares} (Fig. 655). —
The descending or supraclavicular branches arise from the third and fourth
cervical nerves; emerging beneath the dorsal border of the Stern o-mastoid, they
descend in the dorsal triangle of the neck beneath the Platysma and deep
cervical fascia. Near the clavicle they perforate the fascia and Platysma to
become cutaneous, and are arranged, according to their position, into three
groups.
COMMUNICATING TO
HYPOGLOSSAL
SYMPATHETIC
LONGUS COLL. A
RECTUS ANT. MAJOR
TO GENIOHYOID
H^
TOTHYROHYOID
SUBMANDIBULAR
BR. OF FACIAL
LEVATOR ANGULI SCAP.
ASCALENUS MEDIUS
FROM SYMPATHETIC
FIG. 656. — Plan of the cervical plexus. (Gerrish.)
The Internal or Suprasternal Branches (nn. supraclaviculares anteriores] cross
obliquely over the external jugular vein and the clavicular and sternal attach-
ments of the Sterno-mastoid muscle, and supply the integument as far as the
median line. They furnish one or two filaments to the sterno-clavicular joint.
The Middle or Supraclavicular Branches (nn. supraclaviculares medii) cross the
clavicle, and supply the integument over the Pectoral and Deltoid muscles, com-
municating with the cutaneous branches of the upper intercostal nerves.
992 THE NERVE SYSTEM
The External or Supra-acromial Branches (nn. supraclaviculares posteriores] pass
obliquely across the outer surface of the Trapezius and the acromion, and supply
the integument of the upper and back part of the shoulder.
The Deep Branches of the Cervical Plexus (Fig. 656). Internal Series.
The Communicating Branches. — The communicating branches consist of several
filaments which pass from the loop between the first and second cervical nerves
ventrad of the atlas to the vagus, hypoglossal, and sympathetic; of branches
from all four cervical nerves to the superior cervical ganglion of the sympathetic,
together with a branch from the fourth to the fifth cervical.
Muscular Branches. — Muscular branches supply the Anterior recti and Rectus
lateralis muscles; they proceed from the first cervical nerve, and from the loop
formed between it and the second.
The Communicantes Hypoglossi (Fig. 656). — The communicantes hypoglossi
consist usually of two filaments, one being derived from the second and the other
from the third cervical. These filaments pass caudad on the outer side of the
internal jugular vein, cross ventrad of the vein a little below the middle of the
neck, and form a loop with the descendens hypoglossi ventrad of the sheath of
the carotid vessels. Occasionally, the junction of these nerves takes place within
the sheath.
The Phrenic or the Internal Respiratory Nerve of Bell (n. phrenicus] (Figs. 656 and
657). — The phrenic nerve arises chiefly from the fourth cervical nerve, with a few
filaments from the third and a communicating branch from the fifth. It descends
to the root of the neck, running obliquely across the front of the Scalenus anticus
muscle, and beneath the Sterno-mastoid muscle, the posterior belly of the Omo-
hyoid muscle, and the Transversalis colli and suprascapular vessels. It next
passes over the first part of the subclavian artery, between it and the subclavian
vein, and, as it enters the chest, crosses the internal mammary artery near its
origin. Within the chest it descends nearly vertically ventrad of the root of the
lung and by the side of the pericardium, between it and the mediastinal portion
of the pleura, to the Diaphragm, where it divides into branches, some few of
which are distributed to its thoracic surface, but most of which separately pierce
that muscle and are distributed to its under surface (rami phrenicoabdominales).
A ramus pericardiacus is distributed to the pericardium. The two phrenic nerves
differ in their length, and also in their relations at the upper part of the thorax.
The right phrenic nervo is situated more deeply, and is shorter and more vertical
in direction than the left; it lies on the outer side of the right vena innominata
and precava.
The left phrenic nerve is r ther longer than the right, from the inclination of
the heart to the left side, and f om the Diaphragm being lower on this than on the
opposite side. It enters the thorax behind the left innominate vein, and crosses
ventrad of the vagus and the arch of the aorta and the root of the lung. In the
thorax each phrenic nerve is accompanied by a branch of the internal mammary
artery, the comes nervi phrenici.
Each nerve supplies filaments to the Diaphragm, pericardium, and pleura,
and near the chest is joined by a filament from the sympathetic, and, occasion-
ally, by one from the union of the descendens hypoglossi with the spinal nerves;
this filament is found, according to Swan, only on the left side. The phrenic fre-
quently receives a filament from the nerve to the Subclavius muscle. Branches
have been described as passing to the peritoneum.
From the right nerve one or two filaments pass to join in a small ganglion with
phrenic branches of the solar plexus; and branches from this ganglion are dis-
tributed to the hepatic plexus, the adrenal gland, and postcava.
From the left nerve filaments pass to join the phrenic plexus of the sympathetic,
but without any ganglionic enlargement.
THE CERVICAL PLEXUS
993
Surgical Anatomy. — Irritation of the phrenic nerve causes hiccough and persistent cough.
Bilateral paralysis of the phrenic causes death from paralysis of the Diaphragm. This form of
death is seen by the surgeon in fracture-dislocation of the third cervical vertebra. Division of
the phrenic on one side is not fatal, and is occasionally practised by the surgeon in removing
a tumor of the neck. In Hearn's and Franklin's cases of removal of the vagus, the phrenic
was also divided. Unilateral division of the phrenic nerve causes paralysis of the corre-
sponding half of the Diaphragm, which is difficult of recognition, because, as Gowers points out,
the patient can still take deep inspirations, the thoracic muscles not being paralyzed.
VENTRAL PHIMARY
DIVISION OF
FOURTH CERVICAL
3RACHIAL
PLEXUS
PERICARDIAL
BRANCH
PHRENIC
INFERIOR
CERVICAL
GANGLION
INFERIOR
LARYNGEAL
NERVE TO
SUBCLAVIUS
MUSCLE
COMMUNICATING
BRANCH FROM
BRACHIAL PLEXUS
THORACIC CARDIAC
BRANCH OF
VAGUS
INFERIOR
LARYNGEAL
VENTRAL
PULMONARY
VENTRAL
PULMONARY
PLEXUS
RAMIFICATIONS
OF PHRENIC
Fin. 657. — The phrenic nerve and its relations with the vagus nerve. (Toldt.)
The Deep Branches of the Cervical Plexus. External Series. Communi-
cating Branches. — The deep branches of the external series of the cervical plexus
communicate with the accessory nerve, in the substance of the Stern o-mastoid
muscle, in the dorsal triangle, and beneath the Trapezius.
Muscular Branches. — Muscular branches are distributed to the Sterno-mastoid,
Trapezius, Levator anguli scapulae, and Scalenus medius.
The branch for the Sterno-mastoid is derived from the second cervical; the
Trapezius and Levator anguli scapulae receive branches from the third and fourth.
63
994
THE NER VE SYSTEM
The Scalenus medius is derived sometimes from the third, sometimes the fourth,
and occasionally from both nerves.
Surgical Anatomy.— The cervical plexus may be damaged by wounds or contusions, which
may or may not be associated with fracture of the clavicle. Paralysis ensues, the extent depend-
ing on the degree of damage. After a contusion the paralysis is apt to be temporary and to
be followed by pain and muscular spasm in the arm. Paralysis of the arm due to plexus injury
may be partial or complete. In some cases there is complete motor palsy and partial sensor
palsy, the sensor impulses passing along undamaged collaterals. In certain spasmodic diffi-
culties the surgeon occasionally stretches the cervical plexus. It is reached by an incision at the
dorsal margin of the Sternocleidomastoid muscle. This incision begins two inches below
the level of the tip of the mastoid and is carried downward for three inches.
VENTRAL
DIVISION OF
FOURTH CERVICAL"
SUPRASCAPULAR
DESCENDING
BRANCH OF
HYPOGLOSSAL
ANSA
HYPOGLOSSI
THYROID
AXIS
INTERNAL
MAMMARY
ARTERY
SUBCLAVIAN
BRANCH TO
PHRENIC
VENTRAL
THORACIC
FIG. 658. — The right brachial plexus with its short branches, viewed from in front. The Sternocleido-
mastoid and trapezius muscles have been completely, the omohyoid and subclavius have been partially,
removed; a piece has been sawed out of the clavicle; the pectoralis muscles have been incised and reflected.
(Spalteholz.)
The Brachial Plexus (Plexus Brachialis) (Figs. 658, 659, 660).
The brachial plexus is formed by the union of the ventral divisions of the
four lower cervical and the greater part of the first thoracic nerves, receiving usually
a fasciculus from the fourth cervical nerve, and frequently one from the second
thoracic nerve. It extends from the lower part of the side of the neck to the axilla.
It is ve*y broad, and presents little of a plexiform arrangement at its commence-
ment. It is narrow opposite the clavicle, becomes broad and forms a more dense
interlacement in the axilla, and divides opposite the coracoid process into numer-
ous branches for the supply of the upper limb. The nerves which form the plexus
are all similar in size, and their mode of communication is subject to considerable
variation, so that no one plan can be given as applying to every case.1 The follow-
1 Kerr, Bardeen, and Elting, from a study of 175 brachial plexuses, recognized seven types. In 58 per
cent, the outer cord was formed from the fourth to the seventh, the inner cord from the eighth to the ninth
spinal nerves, and the dorsal or posterior cord from the fourth to the ninth. In 30 per cent, the outer cord
was formed from the fifth to the seventh, the inner cord from the eighth to the ninth, and the dorsal cord from
the fifth to the ninth.
THE BRACHIAL PLEXUS
995
ing appears, however, to be the most constant arrangement: above the clavicle
(pars supraclavicidaris) the fifth and sixth cervical unite soon after their exit
MUSCULOCUTANCOUS
NERVE
INTERCOSTC-HUMERAL
NERVES
LESSER INTERNAL
CUTANEOUS NERVES
LONG SUBSCAPULAR
NERVE
SUBSCAPULAR
NERVES
,y LATERAL CUTA-
NEOUS BRANCH
OF FOURTH
INTERCOSTAL
LATERAL CUTANEOUS
BRANCH OF
THIRD INTERCOSTAL
LONG THORACIC
NERVE
Fir,. 659. — The right brachial plexus (infraclavicular portion) in the axillary fossa, viewed from below and
in front. The pectoralis major and minor muscles have been in large part removed; their attachments have
been reflected. (Spalteholz.)
-FROM FOURTH CERVICAL
LEVEL OF THE
CLAVICLE
TO SCALENI A.
LONGUS COLL1
UPPER TRUN
NERVE'TO SUBCLAVIUS
POSTERIOR
THORACIC
Fia. 660.— Plan of the brachial plexus. (Gerrish.)
996
THE NERVE SYSTEM
from the intervertebral foramina to form a common trunk. The eighth cervical
and first thoracic also unite to form one trunk. So that the nerves forming the
plexus, as they lie on the Scalenus medius ectad to the outer border of the
Scalenus anticus muscle, are blended into three trunks — an upper one, formed
FIG. 661. — Cutaneous nerves of right upper
extremity. Ventral view.
FIG. 662.— Cutaneous nerves of right upper
extremity. Dorsal view.
by the junction of the fifth and sixth cervical nerves; a middle one, consisting
of the seventh cervical nerve; and a lower one, formed by the junction of the
eighth cervical and first thoracic nerves. As they pass beneath the clavicle, to
compose the infraclavicular part of the plexus (pars infraclavicularis}, each of
THE BRACHIAL PLEXUS
997
these three trunks divides into two branches, a ventral and a dorsal.1 The ventral
divisions of the upper and middle trunks then unite to form a common cord,
which is situated on the outer
side of the middle part of the
axillary artery, and is called
the outer cord of the brachial
plexus (fasciculus later alls).
The ventral division of the
lower trunk passes caudad on
the inner side of the axillary
artery in the middle of the
axilla, and forms the inner cord
of the brachial plexus (fasciculus
medialis). The dorsal divi-
sions of all three trunks unite
to form the dorsal cord of the
brachial plexus (fasciculus pos-
terior), which is situated be-
hind the second portion of the
axillary artery. From this
dorsal cord are given off the
two lower subscapular nerves,
the upper subscapular nerve
being given off from the dorsal
division of the upper trunk
prior to its junction with the
dorsal division of the lower
and middle trunks. The dor-
sal cord divides into the cir-
cumflex and musculospiral
nerves.
The brachial plexus com-
municates with the cervical
plexus by a branch from the
fourth to the fifth cervical
nerve, and with the phrenic
nerve by a branch from the
fifth cervical, which joins that
nerve on the Anterior scalenus
muscle ; the fifth and sixth cer-
vical nerves are joined by
filaments to the middle cer-
vical ganglion of the sympa-
thetic, the seventh and eighth
cervical to its inferior ganglion,
and the first thoracic nerve to
its first thoracic ganglion.
Close to their exit from the
intervertebral foramina the
nerves give off the filaments
ir\ +Vi£> ranrrlia FIG. 663. — Cutaneous nerves of the upper limb, ventral aspect,
tne ganglia. (W Keiller, in Gerrish's Text-book of Anatomy.)
1 The dorsal division of the lower trunk is verv much smaller than the others, and is frequently derived
entirely from the eighth cervical nerve. — ED. of 15th English edition.
998
THE NER VE SYSTEM
Relations. — In the neck, the brachial plexus lies in the posterior triangle, being
covered by the skin, Platysma, and deep fascia; it is crossed by the posterior belly
of the Omo-hyoid muscle and by the transversalis colli artery. When the dorsal
scapular artery arises from the third part of the subclavian it usually passes between
the roots of the plexus. The plexus lies at first between the Anterior and Middle
scaleni muscles, and then
above and to the outer side
of the subclavian artery; it
next passes behind the clavicle
and Subclavius muscle, lying
upon the first serration of the
Serratus magnus, and the
Subscapularis muscles. It is
in close relation with the apex
of the lung (Luschka). In the
axilla it is placed on the outer
side of the first portion of the
axillary artery; it surrounds
the artery in the second part
of its course, one cord lying
upon the outer side of that
vessel, one on the inner side,
and one behind it, and at the
lower part of the axillary space
gives off its terminal branches
to the upper extremity.
Branches.— The branches
of the brachial plexus are
arranged in two groups — viz.,
those given off above the
clavicle, and those below the
clavicle.
Branches above the Clavicle
(Figs. 658 and 660).— The
branches above the clavicle,
from the pars supraclavicu-
laris, are — the
Communicating.
Muscular.
Long thoracic.
Suprascapular.
The Communicating Branch
(Figs. 657 and 660).— The
communicating branch with
the phrenic is derived from the
fifth cervical nerve or from
the loop between the fifth and
sixth; it joins the phrenic on
the Anterior scalenus muscle.
The communications with the
FIG. 664.— Cutaneous nerve of the upper limb, dorsal aspect. c\rmr>atVip>tir» lin\>p> nlrp>nrl v K<^>n
(W. Keiller, in Gerrish's Text-book of Anatomy.) Sympatnet na\ 6 already DCCH
referred to.
The Muscular Branches (rami muscular es}. — The muscular branches supply the
Longus colli, Scaleni, Rhomboidei, and Subclavius muscles. Those for the
THE BRACHIAL PLEXUS
999
Longus colli and Scaleni arise from the four lower cervical nerves at their exit
from the intervertebral foramina. The Rhomboid branch, called the dorsal
External anterior thoracic.
Internal anterior thoracic.
Muscnlo-cutaneous.
Median.
Musculo-spiral.
—Dorsal
interosseons.
Radial.
Volar
interosseous.
New terms
Old terms.
Intercosto-humeral = Intercosto-brachial.
Posterior thoracic = Long thoracic.
Xerve of Wrisberg = Medial cutaneous nerve of upper arm
(N. cutaneus brachii medialis )
Internal cutaneous = Medial nerve of forearm.
(N. cutaneus antibrachii medialis.)
FIG. 665. — Nerves of the left upper extremity.
1000 THE NERVE SYSTEM
scapular nerve (n. dor sails scapulae] (Figs. 658 and 660), arises from the fifth
cervical, pierces the Scalenus medius, and passes beneath the Levator anguli
scapula?, which it occasionally supplies, to the Rhomboid muscles. The nerve to
the Subclavius (n. subclamus) is a small filament which arises from the fifth cervical
at its point of junction with the sixth nerve; it descends in front of the third part
of the subclavian artery to the Subclavius muscle, and is usually connected by a
filament with the phrenic nerve.
The Long Thoracic or the External Respiratory Nerve of Bell or Posterior Thoracic
Nerve (n. thoracalis longus) (Figs. 658, 659, 660, and 665). — The long thoracic
supplies the Serratus magnus muscle, and is remarkable for the length of its course.
It sometimes arises by two roots from the fifth and sixth cervical nerves immediately
after their exit from the intervertebral foramina, but generally by three roots from
the fifth, sixth, and seventh nerves. These unite in the substance of the Middle
scalenus muscle, and, after emerging from it, the nerve passes caudad behind the
brachial plexus and the axillary vessels, resting on the outer surface of the Serratus
magnus. It extends along the side of the chest to the lower border of that muscle,
supplying filaments to each of the muscular digitations.
The Suprascapular Nerve (n. suprascapularis} (Figs. 658, 660, and 665). — The
suprascapular nerve arises from the cord formed by the fifth and sixth cervical
nerves; passing obliquely outward beneath the Trapezius and the Omo-hyoid, it
enters the supraspinous fossa below the transverse or suprascapular ligament,
and, passing beneath the Supraspinatus muscle, curves around the external border
of the spine of the scapula to the infraspinous fossa. In the supraspinous fossa
it gives off two branches to the Supraspinatus muscle, and an articular filament
to the shoulder-joint; and in the infraspinous fossa it gives off two branches to
the Infraspinatus muscle, besides some filaments to the shoulder-joint and scapula.
Branches below the Clavicle (Figs. 659 and 660). — The branches below the
clavicle, that is, the branches from the pars subclavicularis of the brachial plexus,
are derived from the three cords of the brachial plexus, in the following manner:
From the Outer Cord. — From the outer cord arise the external anterior thoracic
nerve, the musculo-cutaneous, and the outer head of the median.
From the Inner Cord. — From the inner cord arise the internal anterior thoracic
nerve, the medial nerve of the forearm or internal cutaneous, the medial nerve of
the upper arm or lesser internal cutaneous (nerve of Wrisberg), the ulnar, and
inner head of the median.
From the Dorsal Cord. — From the dorsal cord arise two of the three subscapular
nerves, the third taking origin from the dorsal division of the trunk formed by
the fifth and sixth cervical nerves; the cord then divides into the musculo-spiral
and circumflex nerves.
These branches from below the clavicle may be arranged according to the
parts they supply:
To the chest Anterior thoracic.
To the shoulder . { Subscapular.
( Circumflex.
( Musculo-cutaneous.
j Internal cutaneous or medial nerve
of the upper arm.
rr> ^ £ Lesser internal cutaneous or medial
To the arm, forearm, and hand . < ,
nerve of the forearm.
Median.
Ulnar.
Musculo-spiral.
THE BRACHIAL PLEXUS 1001
The fasciculi of which these nerves are composed may be traced through 'the
plexus to the spinal nerves from which they originate. They are as follows :
External anterior thoracic from 5th, 6th, and 7th cervical.
Internal anterior thoracic 8th cervical and 1st thoracic.
Subscapular 5th, 6th, 7th, and 8th cervical.
Circumflex 5th and 6th cervical.
Musculo-cutaneous " 5th and 6th cervical.
Internal cutaneous 8th cervical and 1st thoracic.
Lesser internal cutaneous " 1st thoracic.
Median 6th, 7th, and 8th cervical, and 1st thoracic.
Ulnar 8th cervical and 1st thoracic.
Musculo-spiral " 6th, 7th, and 8th cervical, sometimes also
from the 5th.
NOTE. — In this the reconstructive period of anatomic nomenclature the terms
"anterior" and "posterior" are yet retained in the description of the relations of
structures in the extremities, for "ventral" and "dorsal" are not uniformly applic-
able in the same strict sense as in the trunk and neck regions. Further, the desig-
nations "in front of" and "behind" are applied only to the position of structures
when the body is standing erect and with the volar surface of the hand turned
"forward." The employment of the word "dorsum" for the back of the hand is
already quite general.
The Anterior Thoracic Nerves (mi. thoracales anteriores] (Figs. 658, 659, and 660).
—The anterior thoracic nerves, two in number, supply the Pectoral muscles.
The External or Superficial Anterior Thoracic Nerve (Figs. 658 arid 665), the larger
of the two, arises from the outer cord of the brachial plexus, through which its
fibres may be traced to the fifth, sixth, and seventh cervical nerves. It passes
inward, across the axillary artery and vein, pierces the costo-coracoid membrane,
and is distributed to the under surface of the Pectoralis major muscle. It sends
caudad a communicating filament to join the internal anterior thoracic nerve, and
this communicating filament forms a loop around the inner side of the axillary
artery.
The Internal or Deep Anterior Thoracic Nerve arises from the inner cord and
through it from the eighth cervical and first thoracic nerves. It passes behind
the first part of the axillary artery, then curves forward between the axillary
artery and vein, and joins with the filament from the anterior nerve. It then
passes to the under surface of the Pectoralis minor muscle, where it divides into
a number of branches, which supply the muscle on its under surface. Some
two or three branches pass through the muscle and reach the Pectoralis major.
The Subscapular Nerves (nn. subscapidares} (Figs. 659 and 660). — The sub-
scapular nerves arise from the dorsal cord of the plexus. There are three sub-
scapular nerves, and they supply the Subscapularis, Teres major, and Latissimus
dorsi muscles, and give filaments to the shoulder-joint. The fasciculi of which
they are composed may be traced to the fifth, sixth, seventh, and eighth cervical
nerves.
The First, Short, or Upper Subscapular Nerve, the smallest, arises from the dorsal
division of the upper trunk of origin of the brachial plexus, and enters the upper
part of the Subscapularis muscle ; this nerve is frequently represented by two
branches.
The Second or Lower Subscapular Nerve arises from the dorsal cord of the brachial
plexus, enters the axillary border of the Subscapularis and terminates in the
Teres major. The latter muscle is sometimes supplied by a separate branch.
1002 THE NER VE SYSTEM
The Third, Middle or Long Subscapular Nerve (n. thoracodorsalis) (Fig. 659), the
largest of the three, arises from the dorsal cord of the brachial plexus and follows
the course of the subscapular artery, along the dorsal wall of the axilla to the
Latissimus dorsi muscle, through which it may be traced as far as its lower border.
The Circumflex Nerve (n. axillaris) (Figs. 660 and 666).— The circumflex nerve
supplies some of the muscles, the shoulder-joint, and the integument of the shoulder
(Figs. 661 and 662). It arises from the dorsal cord of the brachial plexus, in
common with the musculo-spiral nerve, and its fibres may be traced through the
dorsal cord to the fifth and sixth cervical nerves. It is at first placed behind the
axillary artery, between it and the Subscapularis muscle, and passes caudad
and outward to the lower border of that muscle. It then winds dorsad in com-
pany with the posterior circumflex artery, through a quadrilateral space bounded
above by the Teres minor muscle, below by the Teres major muscle, internally
by the long head of the Triceps muscle, and externally by the neck of the humerus.
The nerve then divides into two branches.
The Upper Branch (Fig. 666) winds dorsad around the surgical neck of the
humerus, beneath the Deltoid, with the posterior circumflex vessels, as far as the
anterior border of that muscle, supplying it, and giving off cutaneous branches,
which pierce the muscle and ramify in the integument covering its lower part
(Fig. 663).
The Lower Branch (Fig. 666), at its origin, distributes filaments to the Teres
minor and back part of the Deltoid muscles. Upon the filaments to the former
muscle an oval enlargement usually exists. The nerve then pierces the deep
fascia, and supplies the integument over the lower two-thirds of the posterior
surface of the Deltoid (n. cutaneus brachii lateralis), as well as that covering
the long head of the Triceps (caput longum n. tricipitis brachii) (Fig. 664).
The circumflex nerve, before its division, gives off an articular filament, which
enters the shoulder-joint below the Subscapularis muscle.
The Musculo-cutaneous or the External Cutaneous Nerve or the Perforating Nerve
of Casserius1 (n. musculocutaneus) (Figs. 659, 660, and 665). — The musculo-
cutaneous or the external cutaneous nerve supplies some of the muscles of the
arm and the integument of the forearm. It arises from the outer cord of the
brachial plexus, opposite the lower border of the Pectoralis minor muscle,
receiving filaments from the fifth, sixth, and seventh cervical nerves. It perfor-
ates the coraco-brachialis muscle (Fig. 665), passes obliquely between the Biceps
and Brachialis anticus muscles to the outer side of the arm, and, a little above
the elbow, winds around the outer border of the tendon of the Biceps, and, per-
forating the deep fascia, becomes cutaneous (Fig. 661). This nerve, in its course
through the arm, supplies the Coraco-brachialis, Biceps, and the greater part
of the Brachialis anticus muscles. The branch to the Coraco-brachialis is given
off from the nerve close to its origin, and in some instances, as a separate fila-
ment from the outer cord of the plexus. The branches to the Biceps and
Brachialis anticus are given off after the nerve has pierced the Coraco-brachialis.
The nerve also sends a small branch to the humerus, which enters the nutrient
foramen with the accompanying artery, and a filament from the branch supplying
the Brachialis anticus, goes to the elbow-joint. The musculo-cutaneous furnishes
the chief nerve supply to this joint.
The Cutaneous Portion of the Musculo-cutaneous Nerve (n. cutaneus antibrachii
lateralis) passes behind the median cephalic vein, and divides, opposite the elbow-
joint, into an anterior and a posterior branch.
The anterior branch descends along the radial border of the forearm to the
wrist, and supplies the integument over the outer half of the anterior surface. At
1 See foot-note, page 1042.
THE BRACHIAL PLEXUS 1003
the wrist-joint it is placed in front of the radial artery, and some filaments, piercing
the deep fascia, accompany that vessel to the dorsum of the wrist, supplying the
carpus. The nerve then passes distad to the ball of the thumb, where it termi-
nates in cutaneous filaments. It communicates with a branch from the radial
nerve and with the palmar cutaneous branch of the median.
The posterior branch passes distad along the back part of the radial side of the
forearm to the wrist. It supplies the integument of the lower third of the forearm,
communicating with the radial nerve and the external cutaneous branch of the
musculo-spiral. The cutaneous areas supplied by the musculo-cutaneous nerve
are indicated in Figs. 663 and 664.
The musculo-cutaneous nerve presents frequent irregularities. It may adhere
for some distance to the median and then pass outward, beneath the Biceps,
instead of through the Coraco-brachialis. Frequently some of the fibres of the
median run for some distance in the musculo-cutaneous and then leave it to join
their proper trunk. Less frequently the reverse is the case, and the median sends
a branch to joint the musculo-cutaneous. Instead of piercing the Coraco-brachialis
muscle the nerve may pass under it or through the Biceps. Occasionally it gives a
filament to the Pronator radii teres muscle, and it has been seen to supply the
back of the thumb when the radial nerve was absent.
The Internal Cutaneous Nerve (n. cutaneus antibrachii medialis) (Figs. 659, 660,
and 665). — The internal cutaneous nerve or medial cutaneous nerve of the fore-
arm is one of the smallest branches of the brachial plexus. It arises from the
inner cord in common with the ulnar nerve and internal head of the median nerve,
and, at its commencement, is placed on the inner side of the axillary artery, and
afterward of the brachial artery. It derives its fibres from the eighth cervical and
first thoracic nerves. It passes down the inner side of the arm, pierces the deep
fascia with the basilic vein, about the middle of the limb, and, becoming cutaneous,
divides into two branches, anterior and posterior.
This nerve gives off, near the axilla, a cutaneous filament, which pierces the
fascia and supplies the integument covering the Biceps muscle nearly as far as
the elbow. This filament lies a little external to the common trunk, from which
it arises.
The anterior branch, the larger of the two, passes usually in front of, but occa-
sionally behind, the median basilic vein. It then descends on the anterior surface
of the ulnar side of the forearm, distributing filaments to the integument as far
as the wrist, and communicating with a cutaneous branch of the ulnar nerve
(Fig. 661).
The posterior branch passes obliquely distad on the inner side of the basilic
vein, passes in front of, or over, the internal condyle of the humerus to the back
of the forearm, and descends on the posterior surface of its ulnar side as far as
the wrist, distributing filaments to the integument (Fig. 662). It communicates,
above the elbow, with the lesser internal cutaneous nerve, and above the wrist
with the dorsal cutaneous branch of the ulnar nerve (Swan). The cutaneous areas
supplied by the internal cutaneous nerve are indicated in Figs. 663 and 664.
The Lesser Internal Cutaneous Nerve or the Nerve of Wrisberg (n. cutaneus brachii
medialis) (Figs. 659, 660, and 665). — The lesser internal cutaneous nerve or medial
cutaneous nerve of the upper arm is distributed to the integument on the inner
side of the arm. It is the smallest of the branches of the brachial plexus, and,
arising from the inner cord, receives its fibres from the first thoracic nerve. It
passes through the axillary space, at first lying behind, and then on the inner
side of, the axillary vein, and communicates with the intercosto-brachial nerve.
It descends along the inner side of the brachial artery to the middle of the arm,
where it pierces the deep fascia, and is distributed to the integument of the back
of the lower third of the arm, extending as far as the elbow (Figs. 661, 662, and
1004 THE NER VE SYSTEM
663), where some filaments are lost in the integument ventrad of the inner condyle,
and others over the olecranon. It communicates with the posterior branch of
the internal cutaneous nerve.
In some cases the nerve of Wrisberg and the intercosto-brachial or intercosto-
humeral nerve are connected by two or three filaments which form a plexus at the
back part of the axilla. In other cases the intercosto-brachial is of large size,
and takes the place of the nerve of Wrisberg, receiving merely a filament of com-
munication from the brachial plexus, which filament represents the latter nerve.
In other cases this filament is wanting, the place of the nerve of Wrisberg being
supplied entirely by the intercosto-brachial.
The Median Nerve (n. medianns) (Figs. 659, 660, and 665). — The median nerve
has received its name from the course it takes along the middle of the arm and fore-
arm to the hand, lying between the ulnar and musculo-spiral nerves, and the ulnar
and the radial nerves. It arises by two roots, one from the outer and one from
the inner cord of the brachial plexus; these embrace the lower part of the axillary
artery, uniting either in front or on the outer side of that vessel. The median nerve
receives filaments from the sixth, seventh, and eighth cervical and the first thoracic
nerves and sometimes from the fifth cervical as well. As it descends through the
arm, it lies at first on the outer side of the brachial artery, crosses that vessel in
the middle of its course, usually in front, but occasionally behind it, and lies on
its inner side to the bend of the elbow, where it is placed beneath the bicipital
fascia, and is separated from the elbow-joint by the Brachialis anticus muscle.
In the forearm it passes between the two heads of the Pronator radii teres muscle,
and descends beneath the Flexor sublimis muscle, lying on the Flexor profundus
muscle, to within two inches (3 cm.) above the annular ligament, where it becomes
more superficial, lying between the tendons of the Flexor sublimis and Flexor
carpi radialis muscles, beneath, and rather to the radial side or under the tendon
of the Palmaris longus, covered by the integument and fascia. It then passes
through the carpal canal (canalis carpi) beneath the annular ligament into the
hand. In its course through the forearm it is accompanied by the arteria comes
nervi mediani, a branch of the anterior interosseous artery.
Branches.— With the exception of the nerve to the Pronator radii teres muscle,
which sometimes arises above the elbow-joint, and filaments to the elbow-joint,
the median nerve gives off no branches in the arm. In the forearm its branches
are muscular, anterior interosseous, and palmar cutaneous, and two articular twigs
to the elbow-joint.
The Muscular Branches (rami musculares) supply all the superficial muscles on
the front of the forearm except the Flexor carpi ulnaris. These branches are
derived from the nerve near the elbow.
The Volar Interosseous or Anterior Interosseous (n. interosseus [antibrachii]
volaris) (Fig. 665) supplies the deep muscles on the front of the forearm, except
the inner half of the Flexor profundus digitorum. It accompanies the volar
interosseous artery along the interosseous membrane, in the interval between
the Flexor longus pollicis and Flexor profundus digitorum muscles, both of which
it supplies, and terminates below in the Pronator quadratus muscle, sending fila-
ments to the inferior radio-ulnar articulation and the wrist-joint.
The Palmar Cutaneous Branch (ramus cutaneus palmaris n. mediani) arises from
the median nerve at the lower part of the forearm. It pierces the fascia above
the annular ligament, and, descending over that ligament, divides into two
branches; of which the outer branch supplies the skin over the ball of the thumb,
and communicates with the anterior cutaneous branch of the musculo-cutaneous
nerve; and the inner branch supplies the integument of the palm of the hand,
communicating with the cutaneous branch of the ulnar.
In the palm of the hand the median nerve is covered by the integument and
palmar fascia and is crossed by the superficial palmar arch. It rests upon the
THE BRACHIAL PLEXUS 1005
tendons of the flexor muscles. In this situation it becomes enlarged, somewhat
flattened, of a reddish color, and divides into two branches. Of these, the external
branch supplies a muscular branch to some of the muscles of the thumb and
digital branches to the thumb and index finger; the internal branch supplies digital
branches to the contiguous sides of the index and middle and of the middle and
ring fingers. The digital branches, before they subdivide, are called common
palmar digital branches of the median nerve (nn. digitales volares communes).
The branch to the muscles of the thumb (ramus muscularis) is a short nerve which
divides to supply the Abductor, Opponens, and the superficial head of the Flexor
brevis pollicis muscles, the remaining muscles of this group being supplied by
the ulnar nerve.
The Collateral Palmar Digital or the Digital Branches (nn. digitales volares proprii)
are five in number. The first and second pass along the borders of the thumb,
the external branch communicating with branches of the radial nerve. The third
passes along the radial side of the index finger, and supplies the First lumbricalis
muscle. The fourth subdivides to supply the adjacent sides of the index and
middle fingers, and sends a branch to the Second lumbricalis muscle. The fifth
supplies the adjacent sides of the middle and ring fingers, and communicates with
a branch from the ulnar nerve.
Each digital nerve, opposite the base of the first phalanx, gives off a dorsal
branch, which joins the dorsal digital nerve from the radial nerve and runs along
the side of the dorsum of the finger, to end- in the integument over the last phalanx.
At the end of the finger the digital nerve divides into a palmar and a dorsal branch,
the former of which supplies the extremity of the finger, and the latter ramifies
around and beneath the nail. The digital nerves, as they run along the fingers, are
placed superficial to the digital arteries. The cutaneous areas supplied by the
median nerve are shown in Figs. 663 and 664.
The Ulnar Nerve (n. ulnaris) (Figs. 659, 660, and 665). — The ulnar nerve is
placed along the inner or ulnar side of the upper limb, and is distributed to the
muscles and integument of the forearm and hand. It is smaller than the median,
behind which it is placed, diverging from it in its course down the arm. It arises
from the inner cord of the brachial plexus, in common with the inner head of the
median and the internal cutaneous nerve, and derives its fibres from the eighth
cervical and first thoracic nerves. At its commencement it lies to the inner side
of the axillary artery, and holds the same relation with the brachial artery to the
middle of the arm. From this point it runs obliquely across the internal head
of the Triceps, pierces the internal intermuscular septum, and descends to the
groove between the 'internal condyle and the olecranon, accompanied by the in-
ferior profunda artery. At the elbow it rests upon the back of the inner condyle,
and passes into the forearm between the two heads of the Flexor carpi ulnaris
muscle. In the forearm it descends in a perfectly straight course along the ulnar
side of the extremity, lying upon the Flexor profundus digitorum muscle, its
upper half being covered by the Flexor carpi ulnaris muscle, its lower half lying
on the outer side of the muscle, being covered by the integument and fascia.
The ulnar artery, in the upper third of its course, is separated from the ulnar
nerve by a considerable interval, but in the rest of its extent the nerve lies to
its inner side. At the wrist the ulnar nerve crosses the annular ligament on the
outer side of the pisiform bone, to the inner side of and a little behind the ulnar
artery, and immediately beyond this bone divides into two branches, the
superficial and the deep palmar.
Branches. — The branches of the ulnar nerve are —
Articular.
In the forearm
Muscular. T , , , [Superficial palmar.
^ , In the hand -< ^ t
Cutaneous. I Deep palmar.
. Dorsal cutaneous.
1006 THE NERVE SYSTEM
The Articular Branches distributed to the elbow-joint consist of several small
filaments. They arise from the nerve as it lies in the groove between the inner
condyle of the humerus and the olecranon process of the ulnar.
The Muscular Branches (rami musculares) are two in number — one supplying
the Flexor carpi ulnaris; the other, the inner half of the Flexor profundus digi-
torum. They arise from the trunk of the nerve near the elbow.
The Cutaneous Branch arises from the ulnar nerve about the middle of the fore-
arm, and divides into two branches.
One branch (frequently absent) pierces the deep fascia near the wrist, and is
distributed to the integument, communicating with a branch of the internal
cutaneous nerve.
The second branch, the palmar cutaneous (ramus cutaneus palmaris) lies on the
ulnar artery, which it accompanies to the hand, some filaments entwining around
the vessel; it ends in the integument of the palm, communicating with branches
of the median nerve.
The Dorsal Cutaneous Branch (ramus dorsalis manus) arises about two inches
above the wrist; it passes dorsad beneath the Flexor carpi ulnaris muscle,
perforates the deep fascia, and, running along the ulnar side of the back of the
wrist and hand, divides into branches (nn. digitales dorsales)', one of these sup-
plies the inner side of the little finger; a second supplies the adjacent sides of
the little and ring fingers; a third joins the branch of the radial nerve which
supplies the adjoining sides of the middle and ring fingers, and assists in sup-
plying these parts; a fourth is distributed to the metacarpal region of the hand,
communicating with a branch of the radial nerve.
On the little finger the dorsal digital branches extend only as far as the base
of the terminal phalanx, and on the ring finger as far as the base of the second
phalanx; the more distal parts of these digits are supplied by dorsal branches
derived from the palmar digital branches of the ulnar.
The Superficial Palmar Branch (ramus superficialis n. ulnaris} supplies the
Palmaris brevis and the integument on the inner side of the hand, and terminates
in two digital branches, which are distributed, one to the ulnar side of the little
finger, the other to the adjoining sides of the little and ring fingers, the latter
communicating with a branch from the median. The digital branches are dis-
tributed to the fingers in the same manner as the digital branches of the median.
The Deep Palmar Branch (ramus profundus n. ulnaris), accompanied by the
deep branch of the ulnar artery, passes between the Abductor and Flexor brevis
minimi digiti muscles; it then perforates the Opponens minimi digiti and follows
the course of the deep palmar arch beneath the flexor tendons. At its origin it
supplies the muscles of the little finger. As it crosses the deep part of the hand
it sends two branches to each interosseous space, one for the Dorsal and one for
the Palmar interosseous muscle, the branches to the Second and Third palmar
interossei supplying filaments to the two inner Lumbrical muscles. At its ter-
mination between the thumb and index finger, it supplies the Adductores trans-
versus et obliquus pollicis and the inner head of the Flexor brevis pollicis. It also
sends articular filaments to the wrist-joint, and to the bones and joints of the hand.
It will be remembered that the inner part of the Flexor profundus digitorum
muscle is supplied by the ulnar nerve; the two inner Lumbricales, which are
connected with the tendons of this part of the muscle, are therefore supplied by
the same nerve. The outer part of the Flexor profundus is supplied by the
median nerve; the two outer Lumbricales, which are connected with the tendons
of this part of the muscles, are therefore supplied by the same nerve. Brooks
states that in twelve instances out of twenty-one he found that the third lum-
brical received a twig from the median nerve, in addition to its branch from the
ulnar. The palmar branches of the ulnar which go to the fingers are called by
THE BRACHIAL PLEXUS
1007
Circumflex.
Toldt before division common Suprascapuia
palmar digital branches, and
after division collateral palmar
digital branches. The cutane-
ous areas supplied by the ulnar
nerve are shown in Figs. 663
and 664.
The Musculo-spiral Nerve
(n. radiolis) (Figs. 660, 665,
and 666). — The musculospiral
nerve, the largest branch of the
brachial plexus, supplies the
muscles of the back part of the
arm and forearm, and the in-
tegument of the same parts, as
well as that of the back of the
hand (Figs. 663 and 664). It
arises from the posterior cord
of the brachial plexus, of which
it may be regarded as the con-
tinuation. It receives filaments
from the sixth, seventh, and
eighth, and sometimes also
from the fifth cervical and first
thoracic nerves. At its com-
mencement it is placed behind
the axillary artery and the
upper part of the brachial
artery, passing down in front
of the tendons of the Latissi-
mus dorsi and Teres major
muscles. It winds around the
humerus in the musculo-spiral
groove with the superior pro-
funda artery, passing from the
inner to the outer side of the
bone, between the internal and
external heads of the Triceps
muscle (Fig. 666). It pierces
the external intermuscular sep-
tum, and descends between the
Brachialis anticus and Supina-
tor longus muscles to the front
of the external condyle of the
humerus, where it sends filaments to the elbow-joint and divides into the radial
and posterior interosseous nerves.
Branches. — The branches of the musculo-spiral nerve are —
Muscular. Radial.
Cutaneous. Posterior interosseous.
The Muscular Branches (rami musculares n. radialis} are divided into internal,
posterior, and external; they supply the Triceps, Anconeus, Supinator longus,
Extensor carpi radialis longior, and Brachialis anticus muscles. These branches
are derived from the nerve at the inner side, back part, and outer side of the arm.
FIG. 666. — The suprascapular, circumflex, and musculo-spiral
nerves.
1008 THE NERVE SYSTEM
The internal muscular branches supply the inner and middle heads of the Tri-
ceps muscle. That to the inner head of the Triceps is a long, slender filament
which lies close to the ulnar nerve, as far as the lower third of the arm, and is
therefore frequently spoken of as the ulnar collateral branch.
The posterior muscular branch, of large size, arises from the nerve in the groove
between the Triceps muscle and the humerus. It divides into branches which
supply the outer and inner heads of the Triceps and the Anconeus muscles. The
branch for the latter muscle is a long, slender filament which descends in the
substance of the Triceps to the Anconeus.
The external muscular branches supply the Supinator longus, Extensor carpi
radialis longior, and (usually) the outer part of the Brachialis anticus muscles.
The Cutaneous Branches are three in number, one internal and two external.
The internal cutaneous branch (n. cutaneus brachii posterior) arises in the axil-
lary space with the inner muscular branch. It is of small size, and passes through
the axilla to the inner side of the arm, supplying the integument on its posterior
aspect nearly as far as the olecranon. In its course it crosses beneath the inter-
costo-brachial nerve, with which it communicates.
The external cutaneous branch (n. cutaneus antibrachii dorsalis) divides into two
branches, and each one perforates the outer head of the Triceps muscle at its
attachment to the humerus. The upper and smaller one passes to the front of the
elbow, lying close to the cephalic vein, and supplies the integument of the lower half
of the arm on its anterior aspect. The lower branch pierces the deep fascia below
the insertion of the Deltoid muscle, and passes down along the outer side of the
arm and elbow, and then along the back part of the radial side of the forearm to
the wrist, supplying the integument in its course, and joining, near its termination,
with the posterior cutaneous branch of the musculo-cutaneous nerve.
The Radial Nerve (ramus superficial^ n. radialis) (Fig. 665), passes along the front
of the radial side of the forearm to the commencement of its lower third. It lies at
first a little to the outer side of the radial artery, concealed beneath the Supinator
longus muscle. In the middle third of the forearm it lies beneath the same
muscle, in close relation with the outer side of the artery. It leaves the artery
about three inches above the wrist, passes beneath the tendon of the Supinator
longus muscle, and, piercing the deep fascia at the outer border of the forearm,
divides into two branches.
The external branch, the smaller of the two, supplies the integument of the
radial side and ball of the thumb, joining with the anterior branch of the musculo-
cutaneous nerve.
The internal branch communicates, above the wrist, with the posterior cuta-
neous branch from the musculo-cutaneous, and on the back of the hand forms an
arch with the dorsal cutaneous branch of the ulnar nerve. It then divides into
four digital nerves (nn. digitales dorsales), which are distributed as follows: The
first supplies the ulnar side of the thumb; the second, the radial side of the index
finger; the third, the adjoining sides of the index and middle fingers; and the
fourth, the adjacent borders of the middle and ring fingers.1 The latter nerve
communicates with a filament from the dorsal branch of the ulnar nerve.
The Dorsal or Posterior Interosseous Nerve (n. interosseus [antibrachii] dorsalis)
(Figs. 665 and 666). — The dorsal interosseous nerve winds to the back of the
forearm around the outer side of the radius, passes between the two planes of
fibres of the Supinator brevis muscle, and is prolonged distad between the super-
ficial and deep layer of muscles, to the middle of the forearm. Considerably
diminished in size, it descends on the interosseous membrane, beneath the Extensor
longus pollicis muscle, to the back of the carpus, where it presents a gangliform
1 According to Hutchinson, the digital nerve to the thumb reaches only as high as the root of the nail; the
one to the forefinger as high as the middle of the second phalanx, and the one to the middle and ring fingers not
higher than the first phalangeal joint (London Hospital Gazette, vol. iii, p. 319).— ED. 15th English edition.
THE BRACHIAL PLEXUS 1009
enlargement from which filaments are distributed to the inferior radio-ulnar
articulation, to the wrist-joint, and to the ligaments and articulations of the carpus.
It supplies all the muscles of the radial and posterior brachial regions, excepting
the Anconeus, Supinator longus, and Extensor carpi radialis longior.
Surgical Anatomy. — The brachial plexus may be ruptured by traction on the limb, leading
to complete paralysis. Bristow1 has reported three cases of avulsion of the plexus and has
described twenty-four cases. In these cases it is generally believed that the lesion is rather a
tearing away of the nerves from the spinal cord than a solution of continuity of the nerve-fibres
themselves. In a case operated upon by Bristow it was found that the plexus had given way
where the four cervical nerves and the first thoracic nerve unite to form three trunks. In supracla-
vicular division of the brachial plexus, not only will there be motor and sensor paralysis in the
limb, but the Serratus magnus muscle will probably be paralyzed, because of injury to the dorsal
thoracic nerves. In the axilla any of the nerves forming the brachial plexus may be injured by a
wound of this part, the median being the one which is most frequently damaged from its exposed
position. The musculo-spiral, on account of its sheltered and deep position, is least often
wounded. The brachial plexus in the axilla is often damaged from the pressure of a crutch, pro-
ducing the condition known as crutch paralysis. In these cases the musculo-spiral is the nerve most
frequently implicated; the ulnar nerve being the one that appears to suffer next in frequency.
The circumflex nerve is of particular surgical interest. On account of its course around the
surgical neck of the humerus, it is liable to be torn in fractures of this part of the bone, and
in dislocations of the shoulder-foint, leading to paralysis of the deltoid, and, according to Erb,
inflammation of the shoulder-joint is liable to be followed by a neuritis of this nerve from extension
of the inflammation to it.
Mr. Hilton takes the circumflex nerve as an illustration of a law which he lays down, that
"the same trunks of nerves whose branches supply the groups of muscles moving a joint furnish
also a distribution of nerves to the skin over the insertions of the same muscles, and the interior
of the joint receives its nerves from the same source" In this way he explains the fact that an
inflamed joint becomes rigid, because the same nerves which supply the interior of the joint
supply the muscles which move that joint.
The median nerve is liable to injury in wounds of the forearm. When paralyzed, there is
loss of flexion of the second phalanges of all the fingers and of the terminal phalanges of the
index and middle fingers. Flexion of the terminal phalanges of the ring and middle fingers can
still be effected by that portion of the Flexor profundus digitorum which is supplied by the ulnar
nerve. There is power to flex the proximal phalanges through the Interossei. The thumb
cannot be flexed or opposed, and is maintained in a position of extension and adduction. All
power of pronation is lost. The wrist can be flexed, if the hand is first adducted, by the action
of the Flexor carpi ulnaris. There is loss or impairment of sensation on the palmar surface
of the thumb, index, middle, and outer half of the ring fingers, and on the dorsal surface of the
same fingers over the last two phalanges; except in the thumb, where the loss of sensation is
limited to the back of the last phalanx. In order to expose the median nerve for the purpose
of stretching it an incision should be made along the radial side of the tendon of the Palmaris
longus muscle, which serves as a guide to the nerve.
The ulnar nerve is liable to be injured in wounds of the forearm. When paralyzed, there
is loss of power of flexion in the ring and little fingers; there is impaired power of ulnar
flexion and adduction of the hand; there is inability to spread out the fingers from paralysis of
the Interossei; and there is inability to adduct the thumb. The fingers cannot be flexed at the
first joints, and cannot be extended at the other joints. A claw-hand develops, the first pha-
langes being overextended and the others flexed. Sensation is lost or impaired in the skin of the
ulnar side of the hand anteriorly and posteriorly, involving the little finger, the ring finger, and
the ulnar half of the middle finger posteriorly, and anteriorly involving the little finger and the
ulnar half of the ring finger. In order to expose the nerve in the lower part of the forearm,
an incision should be made along the outer border of the tendon of the Flexor carpi ulnaris, and
the nerve will be found lying on the ulnar side of the ulnar artery.
The musculo-spiral nerve is probably more frequently injured than any other nerve of the
upper extremity. In consequence of its close relationship to the humerus as it lies in the
musculo-spiral groove, it is frequently torn or injured in fractures of this bone, or subsequently
involved in the callus that may be thrown out around a fracture, and thus pressed upon and its
funetions interfered with. It is also liable to be squeezed against the bone by kicks or blows and
it may be divided by wounds of the arm. When paralyzed, the hand is flexed at the wrist
and lies flaccid. This condition is known as drop-wrist. The fingers are also flexed, and on
an attempt being made to extend them the last two phalanges only will be extended through the
action of the Interossei, the first phalanges remaining flexed. There is no power of extending
the wrist. Supination is completely lost when the forearm is extended on the arm, but is
1 Annals of Surgery, September, 1902.
64
1010 THE NERVE SYSTEM
possible to a certain extent if the forearm is flexed so as to allow of the action of the Biceps.
The power of extension of the forearm is lost on account of paralysis of the Triceps. Loss of
sensation may be considerable or slight. Its area is shown in Fig. 664. The best position in
which to expose the nerve for the purpose of stretching is to make an incision along the inner border
of the Supinator longus muscle, just above the level of the elbow-joint. The skin and superficial
structures are to be divided and the deep fascia exposed. The white line in this structure indicat-
ing the border of the muscle is to be defined, and the deep fascia divided in this line. By now raising
the Supinator longus the nerve will be found lying beneath it, on the Brachialis anticus muscle.
Post-anaesthetic paralysis. When a person emerges from the influence of a general anaesthetic
palsy of the arm may be found to exist. The brachial plexus may have been compressed during
the operation by drawing the arm strongly from the body or elevating it by the side of the
head. In such a case the plexus was compressed by the head of the humerus (Braun).
The median nerve is stretched when the arm is rotated externally and drawn backward and
outward. The ulnar nerve is stretched when the forearm is flexed and supinated (Braun).
Garrigues believes that in most cases of post-anaesthetic paralysis the brachial plexus was squeezed
between the collar bone and the first rib by the head of the patient being drawn to the opposite
side or being allowed to fall back.
THE THORACIC NERVES (NN. THORACALES).
The thoracic nerves are twelve in number on each side. The first appears
between the first and second thoracic vertebrae, and the last between the last
thoracic and first lumbar.
The Roots of the Thoracic Nerves.
The roots of the thoracic nerves are of small size, and vary but slightly from
the second to the last. Both roots are very slender, the dorsal roots slightly
exceeding the ventral in thickness. They gradually increase in length from
above downward, and in the lower part of the thoracic region pass down in con-
tact with the spinal cord for a distance equal to the height of at least two vertebrae,
before they emerge from the vertebral canal. They then join in the intervertebral
foramen, and at their exit divide into two primary divisions, a dorsal (posterior)
and a ventral (intercostal).
The Dorsal Divisions of the Thoracic Nerves (Kami Posteriores).
The dorsal divisions of the thoracic nerves are smaller than the ventral, pass
dorsad between the transverse processes, and divide into medial or internal and
lateral or external branches.
The Medial Branches. — The medial branches of the six upper nerves pass
inward between the Semispinalis dorsi and Multifidus spinse muscles, which they
supply, and then, piercing the origins of the Rhomboidei and Trapezius muscles,
become cutaneous by the side of the spinous processes and ramify in the integu-.
ment. The medial branches of the six lower nerves are distributed to the
Multifidus spinse, without giving off any cutaneous filaments.
The Lateral Branches. — The lateral branches increase in size from above
caudad. They pass through the Longissimus dorsi muscle to the cellular inter-
val between it and the Iliocostalis muscle, and supply those muscles, as well
as their continuations cephalad to the head, and also the Levatores costarum
muscles; the five or six lower nerves also give off cutaneous filaments, which pierce
the Serratus posticus inferior and Latissimus dorsi muscles in a line -with the
angles of the ribs, and then ramify in the integument.
The Cutaneous Branches. — The cutaneous branches of the dorsal primary
divisions of the thoracic nerves are twelve in number. From each ramus medialis
of the upper six nerves comes a ramus cutaneus medialis, and from each ramus
VENTRAL DIVISIONS OF THE THORACIC NERVES 1011
lateralis of the lower six nerves comes a ramus cutaneus lateralis. The six upper
cutaneous nerves are derived from the medial branches of the dorsal divisions
of the thoracic nerves. They pierce the origins of the Rhomboidei and Trapezius
muscles, and become cutaneous by the side of the spinous processes, and then
ramify in the integument. They are frequently furnished with gangliform enlarge-
ments. The six lower cutaneous nerves are derived from the lateral branches
of the dorsal divisions of the thoracic nerves. They pierce the Serratus posticus
inferior and Latissimus dorsi muscles in a line with the angles of the ribs, and
then ramify in the integument.
The Ventral Divisions of the Thoracic Nerves or the Intercostal Nerves
(Rami Anteriores).
The ventral divisions of the thoracic nerves or the intercostal nerves (nn. inter-
costales) are twelve in number on each side. They are, for the most part,
distributed to the parietes of the thorax and abdomen, separately from each
other, without being joined in a plexus; in which respect they differ from the
other spinal nerves. Each nerve is connected with the adjoining ganglion of the
sympathetic by one or two filaments (ramus communicans). The intercostal nerves
may be divided into two sets, from the difference they present in their distribution.
The six upper, with the exception of the first and the intercosto-brachial branch
of the second, are limited in their distribution to the parietes of the chest. The
six lower supply the parietes of the chest and abdomen, the last one sending a
cutaneous filament to the buttock.
The Ventral Division of the First Thoracic Nerve.— The ventral division
of the first thoracic nerve divides into two branches: one, the larger, leaves the
thorax ventrad of the neck of the first rib, and enters into the formation of the
brachial plexus ; the other and smaller branch runs along the first intercostal space,
forming the first intercostal nerve (n. intercostalis 7), giving off muscular branches,
and terminates on ventral part of the chest by forming the first ventral cutaneous
nerve (ramus cutaneus anterior n. intercostalis 1} of the thorax. Occasionally
this ventral cutaneous branch is wanting. The first intercostal nerve, as a rule,
gives off no lateral cutaneous branch, but sometimes a small branch is given off
which communicates with the intercosto-brachial. It frequently receives a con-
necting twig from the second thoracic nerve, which passes upward over the neck
of the second rib.
The Ventral Divisions of the Upper Thoracic Nerves (nn. intercostales).
—The ventral divisions of the second, third, fourth, fifth, and sixth thoracic
nerves and the small branch from the first thoracic are confined to the parietes
of the thorax, and are named upper or pectoral intercostal nerves. They pass
forward in the intercostal spaces with the intercostal vessels, being situated below
them. At the back of the chest they lie between the pleura and the External
intercostal muscle, but are soon placed between the two planes of Intercostal
muscles as far as the middle of the rib. They then enter the substance of the
Internal intercostal muscles, and, running amidst their fibres as far as the costal
cartilages, they gain the inner surface of the muscles and lie between them and
the pleura. Near the sternum, they cross ventrad of the internal mammary artery
and Triangularis sterni muscle, pierce the Internal intercostal muscles, the anterior
intercostal membrane, and Pectoralis major muscle, and supply the integument
of ventral wall of the chest and over the mammary gland, forming the ventral
cutaneous nerves of the thorax; the branch from the second nerve is joined with
the supraclavicular nerves of the cervical plexus.
Branches. — Numerous slender muscular filaments (rami musculares) supply the
Intercostals, the Infracostales, the Levatores costarum, Serratus posticus superior,
1012
THE NERVE SYSTEM
and Triangularis sterni muscles. Some of these branches, in the ventral wall
of the chest, cross the costal cartilages from one to another intercostal space.
Lateral Cutaneous Nerves of the Thorax (rami cutanei laterales [pectorales]) (Fig.
659). — These are derived from the intercostal nerves, midway between the vertebrae
and sternum; they pierce the External intercostal and Serratus magnus muscles,
and divide into two branches, ventral and dorsal.
The Ventral Branches (rami anteriores) are reflected forward to the side and the
forepart of the chest, supplying the integument of the chest and mamma; those
of the fifth and sixth nerves supply the upper digitations of the External oblique
muscle.
Ventral aspect.
FIG. 667. — Distribution of cutaneous nerves.
The Dorsal Branches (rami posteriores) are reflected dorsad to supply the integu-
ment over the scapula and over the Latissimus dorsi muscle.
The Lateral Cutaneous Branch of the Second Intercostal Nerve (n. intercosto-
brachialis) is of large size, and does not divide, like the other nerves, into a
ventral and dorsal branch. It may unite with a branch of the third intercostal.
The single nerve or the united nerve is named, from its origin and distribution, the
VENTRAL DIVISIONS OF THE THORACIC NERVES
1013
intercosto-brachial or intercosto-humeral nerve (Figs. 659 and 665). It pierces the
External intercostal muscle, crosses the axilla to the inner side of the arm, and
joins with a filament from the medial cutaneous nerve of the upper arm (nerve
of Wrisberg}. It then pierces the fascia, and supplies the skin of the upper
half of the inner and back part of the arm (Figs. 663 and 664), communicating
with the internal cutaneous branch (n. cutaneus antibrachii medialis] of the
musculo-spiral nerve. The size of this nerve is in inverse proportion to the size
of the other cutaneous nerves, especially the nerve of Wrisberg. A second inter-
costo-brachial nerve is frequently given off from the third intercostal. It supplies
filaments to the armpit and inner side of the arm. It may or may not send a
branch to the intercosto-brachial.
/INTERNAL BRANCH
(CUTANEOUS)
EXTERNAL BRANCH
(MUSCULAR)
DORSAL
PRIMARY DIVISION
VENTRAL CUTANEOUS
FIG. 668. — Plan of a typic intercostal nerve. (W. Keiller.)
The Ventral Divisions of the Lower Thoracic Nerves. — The ventral divisions
of the seventh, eighth, ninth, tenth, and eleventh thoracic nerves are continued
ventrad from the intercostal spaces into the abdominal wall, and the twelfth
thoracic is continued throughout its whole course in the abdominal wall, since
it is placed below the last rib; hence these nerves are named lower or abdom-
inal intercostal nerves. They have (with the exception of the last) the same arrange-
ment as the upper ones as far as the anterior extremities of the intercostal spaces,
where they pass behind the costal cartilages, and between the Internal oblique and
Transversalis muscles, to the sheath of the Rectus, which they perforate. They
supply the Rectus muscle, and terminate in branches which become subcutaneous
near the linea alba. These branches are named the ventral or anterior cutaneous
nerves of the abdomen. They are directed outward as far as the lateral cutaneous
nerves, supplying the integument of the front of the belly. The lower intercostal
nerves supply the Intercostals, Serratus posticus inferior, and Abdominal muscles,
and, about the middle of their course, give off lateral cutaneous branches which
1014 THE NERVE SYTSEM
pierce the External intercostal and External oblique muscles, in the same line as
the lateral cutaneous nerves of the thorax, and divide into ventral and dorsal
branches, which are distributed to the integument of the abdomen and back; the
ventral branches supply the digitations of the External oblique muscle and extend
caudad and forward nearly as far as the margin of the Rectus muscle; the dorsal
branches pass dorsad to supply the skin over the Latissimus dorsi muscle.
The Last Thoracic Nerve.— The last thoracic is larger than the other thoracic
nerves. Its ventral division runs along the lower border of the last rib, and passes
under the external arcuate ligament of the Diaphragm. It then runs ventrad of
the Quadratus lumborum muscle, perforates the Transversalis muscle, and passes
distad between it and the Internal oblique muscle, to be distributed in the
same manner as the lower intercostal nerves. It communicates with the ilio-
hypogastric branch of the lumbar plexus, and is frequently connected with the
first lumbar nerve by a slender branch, the thoracico-lumbar nerve, which descends
in the substance of the Quadratus lumborum muscle. It gives a branch to the
Pyramidalis muscle.
The Cutaneous Branches. — There are two cutaneous branches, a ventral and a
lateral.
The Ventral Cutaneous Branch is a terminal branch and is a direct prolongation
of the intercostal. It supplies an area of skin of the abdominal wall between
the umbilicus and pubis.
The Lateral Cutaneous Branch (ramus cutaneus lateralis [abdominalis] inter-
costalis XII) is remarkable for its large size; it perforates the Internal and Exter-
nal oblique muscles, passes over the crest of the ilium ventrad of the iliac branch
of the ilio-hypogastric, and is distributed to the integument of the front part of
the gluteal region, some of its filaments extending as low down as the trochanter
major. It does ijot divide into a ventral and a dorsal branch, like the other
lateral cutaneous branches of the intercostal nerves.
Surgical Anatomy. — The lower seven intercostal nerves and the ilio-hypogastric from the
first lumbar nerve supply the skin of the abdominal wall. They run caudad and inward
fairly equidistant from each other. The sixth and seventh supply the skin over the "pit of the
stomach;" the eighth corresponds to about the position of the middle linea transversa; the
tenth to the umbilicus; and the ilio-hypogastric supplies the skin over the pubes and external
abdominal ring. There are several points of surgical significance about the distribution of these
nerves, and it is important to remember their origin and course, for in many diseases affecting
the nerve-trunks at or near their origin the pain is referred to their peripheral origins. Thus
in Pott's disease of the spine children will often be brought to the surgeon suffering from pain
in the belly. This is due to the fact that the nerves are irritated at the seat of disease as they
issue from the spinal canal. When the irritation is confined to a single pair of nerves, the sen-
sation complained of is often a feeling of constriction, as if a cord were tied around the abdomen;
and in these cases the situation of the sense of constriction may serve to localize the disease in
the spinal column. In other cases, where the bone disease is more extensive and two or more
nerves are involved, a more diffused pain in the abdomen is complained of. A similar conditon
is sometimes present in affections of the cord itself, as in tabes dorsalis.
Again, it must be borne in mind that the same nerves which supply the skin of the abdomen
supply also the muscles which constitute the greater part of the abdominal wall. Hence, it follows
that any irritation applied to the peripheral terminations of the cutaneous branches in the
skin of the abdomen is immediately followed by reflex contraction of the abdominal muscles.
A good practical illustration of this may sometimes be seen in watching two surgeons examine
the abdomen of the same patient. One, whose hand is cold, causes the muscles of the abdom-
inal wall to at once contract and the belly to become rigid, and thus not nearly so suitable
for examination; the other, who has taken the precaution to warm his hand, examines the
abdomen without exciting any reflex contraction. The supply of both muscles and skin from
the same source is of importance in protecting the abdominal viscera from injury. A blow
on the abdomen, even of a severe character, will do no injury to the viscera if the muscles are
in a condition of firm contraction; whereas in cases where the muscles have been taken unawares,
and the blow has been struck while they were in a state of rest, an injury insufficient to produce
any lesion of the abdominal wall has been attended with rupture of some of the abdominal con-
tents. The importance, therefore, of immediate reflex contraction upon the receipt of an injury
THE VENTRAL DIVISIONS OF THE LUMBAR NERVES 1015
c-innot be overestimated, and the intimate association of the cutaneous and muscular fibres in
the same nerve produces a much more immediate response on the part of the muscles to any
peripheral stimulation of the cutaneous filaments than would be the case if the two sets of fibres
were derived from independent sources.
Again, the nerves supplying the abdominal muscles and skin are derived from the lower inter-
costal nerves and are intimately connected with the sympathetic supplying the abdominal viscera
through the lower thoracic ganglia from which the splanchnic nerves are derived. In conse-
quence of this, in rupture of the abdominal viscera and in acute peritonitis the muscles of the
belly-wall become firmly contracted, and thus as far as possible preserve the abdominal contents
in a condition of rest.
THE LUMBAR NERVES (NN. LUMBALES).
The lumbar nerves are five in number on each side. The first lumbar nerve
appears between the first and second lumbar vertebrae, and the last between the
last lumbar vertebra and the base of the sacrum.
The Roots of the Lumbar Nerves.
The roots of the lumbar nerves are the largest, and their filaments the most
numerous, of all the spinal nerves, and they are closely aggregated together upon
the lower end of the cord. The ventral roots are the smaller, but there is not the
same disproportion between them and the dorsal roots as in the cervical nerves.
The roots of these nerves have a vertical direction, and are of considerable length,
more especially the lower ones, since the spinal cord does not extend beyond the
first lumbar vertebra. The roots become joined in the intervertebral foramina,
and the nerves so formed divide at their exit into two divisions, dorsal and ventral.
The Dorsal Divisions of the Lumbar Nerves (Kami Posteriores).
The dorsal divisions of the lumbar nerves diminish in size from above down-
ward; they pass dorso-laterad between the transverse processes, and divide into
medial and lateral branches.
The Medial Branches (rami mediales). — The medial branches, the smaller,
pass inward close to the articular processes of the vertebrae, and supply the Multi-
fidus spinse and Interspinales muscles.
The Lateral Branches (rami later ales). — The lateral branches supply the
Erector spinse and Intertransverse muscles. From the three upper branches
cutaneous nerves are derived which pierce the aponeurosis of the Latissimus dorsi
muscle and descend over the dorsum of the crest of the ilium, to be distributed
to the integument of the gluteal region, some of the filaments passing as far as the
trochanter major (Fig. 672).
The dorsal division of the fifth lumbar nerve usually sends a branch which
forms a loop with the dorsal division of the first sacral nerve.
The Ventral Divisions of the Lumbar Nerves (Rami Anteriores).
The ventral divisions of the lumbar nerves increase in size from above cau-
dad. At their origin they communicate with the lumbar ganglia of the sym-
pathetic by long, slender filaments, which accompany the lumbar arteries around
the sides of the bodies of the vertebrae, beneath the Psoas muscle. The nerves pass
obliquely outward behind the Psoas magnus or between its fasciculi, distributing
filaments to it and the Quadratus lumborum. The ventral divisions of the five
lumbar, five sacral, and first coccygeal nerve constitute the lumbo-sacral plexus
(plexus lumbosacralis). This is subdivided into the lumbar plexus, the sacral
plexus, and the pudendal plexus. The ventral divisions of the four upper nerves
1016
THE NER VE SYSTEM
are connected together in this situation by anastomotic loops, and form the lumbar
plexus. The ventral division of the fifth lumbar, joined with a branch from the
fourth, descends across the base of the sacrum to join the ventral division- of the
first sacral nerve and assists in the formation of the sacral plexus. The cord result-
ing from the union of the fifth lumbar and the branch from the fourth is called
the lumbo-sacral cord (truncus lumbosacralis) (Figs. 670 and 675).
The Lumbar Plexus (Plexus Lumbalis) (Figs. 669, 670).
The lumbar plexus is formed by the loops of communication between the
ventral divisions of the four upper lumbar nerves. The plexus is narrow above,
and often connected with the last thoracic nerve by a slender branch, the dorsi-
lumbar nerve. The plexus is broad below, where it is joined to the sacral plexus
by the lumbo-sacral cord. The lumbar plexus is situated in the substance of
the Psoas muscle near its dorsal part, in front of the transverse processes of
the lumbar vertebrae.
The mode in which the plexus is arranged varies in different subjects.1 It
differs from the brachial plexus in not forming an intricate interlacement, but the
several nerves of distribution
- ^u , XI I
arise from one or more of
the spinal nerves in the fol-
lowing manner: The first
lumbar nerve receives a
branch from the last tho-
racic, gives off a larger
branch, which subdivides
into the ilio-hypogastric and
ilio-inguinal nerves; the first
lumbar also gives off a com-
municating branch which
IV passes down to the second
tumbar nerve, and a third
branch which unites with
, a branch of the second
lumbar, to form the genito-
femoral nerve. The second,
third, and fourth lumbar
nerves divide into ventral
and dorsal divisions. The
ventral division of the second
divides into two branches, one of which joins with the above-mentioned branch
of the first nerve to form the genito-femoral ; the other unites with the ventral
division of the third nerve, and a part of the ventral division of the fourth nerve
to form the obturator nerve. The remainder of the ventral division of the fourth
nerve passes down to communicate with the fifth lumbar nerve. The dorsal
divisions of the second and third nerves divide into two branches, a smaller
branch from each uniting to form the lateral or external cutaneous nerve, and a larger
branch from each, which join the whole of the dorsal division of the fourth
lumbar nerve to form the femoral or anterior crural nerve. The accessory obturator,
when it exists, is formed by the union of two small branches given off from the
third and fourth nerves.
From this arrangement it follows that the ilio-hypogastric and ilio-inguinal
are derived entirely from the first lumbar nerve; the genito-femoral from the first
ILIO-HYPOGASTRIC
ILIO-INGUINAL
GENITO-FEMORAL
LATERAL
CUTANEOUS
TO PSOAS AND
ILIACUS
FEMORAL (ANTFRIOR
CRURAL)
OBTURATOR l(-
OBTURATOR^,
FIG. 669. — Diagram of the lumbar plexus.
1 For statistical studies of the variations encountered in different individuals, see the article by Bardeen
in the American Journal of Anatomy.
THE LUMBAR PLEXUS
1017
and second nerves; the lateral cutaneous from the second and third; the femoral
and obturator by fibres derived from the second, third, and fourth; and the
accessory obturator, when it exists, from the third and fourth.
Branches (Figs. 669 and 670). — The branches of the lumbar plexus are — the
Ilio-hypogastric.
Ilio-inguinal.
Genito-femoral.
Lateral cutaneous.
Obturator.
Accessory obturator.
Femoral (Anterior crural).
The Ilio-hypogastric Nerve (n. iliohypogastricus) (Figs. 669 and 670). — The
ilio-hypogastric nerve arises from the first lumbar nerve. It emerges from the
outer border of the Psoas muscle at its upper part, and crosses obliquely ventrad
of the Quadratus lumborum to the crest of the ilium. It then perforates the
Transversalis muscle dorsally near the crest of the ilium. It gives off muscular
branches (rami muscuiares} to the abdominal wall, and divides between the Trans-
versalis and the Internal oblique into two cutaneous branches, iliac and hypogastric.
FIG. 670. — The lumbar plexus and its branches.
The Iliac Branch (ramus cutaneus lateralis) pierces the Internal and External
oblique muscles immediately above the crest of the ilium, and is distributed to the
integument of the gluteal region, behind the lateral cutaneous branch of the last
thoracic nerve (Fig. 676). The size of this nerve bears an. in verse proportion to
that of the cutaneous branch of the last thoracic nerve.
1018 THE NERVE SYSTEM
The Hypogastric Branch (ramus cutaneus anterior) (Fig. 671) continues onward be-
tween the Internal oblique and Transversalis muscles. It then pierces the Internal
oblique, and becomes cutaneous by perforating the aponeurosis of the External
oblique, about an inch (2 cm.) above and a little laterad of the external abdominal
ring, and is distributed to the integument of the hypogastric region. The ilio-
hypogastric nerve communicates with the last thoracic and ilio-inguinal nerves.
The Ilio-inguinal Nerve (n. ilioinguinalis) (Figs. 669, 670, and 671). — The ilio-
inguinal nerve, smaller than the preceding, arises with it from the first lumbar
nerve. It emerges from the outer border of the Psoas muscle just below the ilio-
hypogastric nerve, and, passing obliquely across the Quadratus lumborum and
Iliacus muscles, perforates the Transversalis near the forepart of the crest of the
ilium, and communicates with the ilio-hypogastric nerve between that muscle and
the Internal oblique. The nerve then pierces the Internal oblique, distributing
muscular branches (rami muscidares) to it, and, accompanying the spermatic
cord through the external abdominal ring, is distributed to the integument of the
upper and inner part of the thigh, and to the scrotum in the male (nn. scrotales
anteriores) and to the labium majus in the female (nn. labiales anteriores). The
size of this nerve is in inverse proportion to that of the ilio-hypogastric. Occa-
sionally it is very small, and ends by joining the ilio-hypogastric; in such cases a
branch from the ilio-hypogastric takes the place of the ilio-inguinal, or the ilio-
inguinal nerve may be altogether absent.
The Genito-femoral or Genito-crural Nerve (n. genitofemoralis) (Figs. 669 and
670) arises from the first and second lumbar nerves. It passes obliquely through
the substance of the Psoas muscle, and emerges from its inner border at a level
corresponding to the intervertebral substance between the third and fourth
lumbar vertebrae; it then descends on the surface of the Psoas muscle, under cover
of the peritoneum, and divides into a genital and a femoral branch.
The Genital Branch or External Spermatic Nerve (n. spermaticus externus) passes
outward on the Psoas magnus, and pierces the fascia transversalis, or passes
through the internal abdominal ring; in the male it then descends along the back
part of the spermatic cord to the scrotum, and supplies the Cremaster muscle.
In the female it accompanies the round ligament, and is lost upon it.
The Femoral Branch or Lumbo-inguinal Nerve (n. lumboinguinalis) (Fig. 671)
descends on the external iliac artery, sending a few filaments around it, and,
passing beneath Poupart's ligament to the thigh, enters the sheath of the femoral
vessels, lying superficial and a little external to the femoral artery. It pierces the
anterior layer of the sheath of the vessels, and, becoming superficial by passing
through the fascia lata, it supplies the skin of the anterior aspect of the thigh as
far as midway between the pelvis and knee. On the front of the thigh it com-
municates with the outer branch of the middle cutaneous nerve, derived from the
femoral nerve. A few filaments from this nerve may be traced on to the femoral
artery; they are derived from the nerve as it passes beneath Poupart's ligament.
The Lateral Cutaneous Nerve, (n. cutaneus femoris lateralis) (Figs. 669, 670,
671, and 672). — The lateral cutaneous nerve arises from the second and third
lumbar nerves. It emerges from the outer border of the Psoas muscle about its
middle, and crosses the Iliacus muscle obliquely, toward the anterior1 superior
spine of the ilium. It then passes under Poupart's ligament and over the Sartorius
muscle into the thigh, where it divides into two branches, anterior and posterior.
The Anterior Branch descends in an aponeurotic canal formed in the fascia lata,
becomes superficial about four inches below Poupart's ligament, and divides into
branches which are distributed to the integument along the anterior and outer
part of the thigh, as far down as the knee. This nerve occasionally communicates
with a branch of the long saphenous nerve in front of the knee-joint.
1 Cf. note on p. 1005.
THE LUMBAR PLEXUS
1019
Rural or
external f
sapfienous.
Femoral or
anterior crural.
-Anterior tibial.
— Anterior division
of obturator.
Internal
cutaneous.
Saphenous.
FIG. 671. — Cutaneous nerves of lower
extremity. Front view.
FIG. 672. — Nerves of the lower extremity.
Front view.
1020 THE NERVE SYSTEM
The Posterior Branch pierces the fascia lata, and subdivides into branches which
pass dorsad across the outer and posterior surface of the thigh, supplying the
integument from the crest of the ilium as far as the knee.
The Obturator Nerve (n. obturatorius) (Figs. 669, 670, and 672). — The obturator
nerve supplies the Obturator externus and Adductor muscles of the thigh, the
articulations of the hip and knee, and occasionally the integument of the thigh
and leg. It arises by three branches — from the second, the third, and the fourth
lumbar nerves. Of these, the branch from the third is the largest, while that
from the second is often very small. It descends through the inner fibres of the
Psoas muscle, and emerges from its inner border near the brim of the pelvis; it then
runs along the lateral wall of the pelvis, above the obturator vessels, to the upper
part of the obturator foramen, where it enters the thigh, and divides into an
anterior and a posterior branch, separated by some of the fibres of the Obturator
externus muscle, and lower down by the Adductor brevis muscle.
The Anterior Branch (ramus anterior} (Fig. 672) passes down in front of the
Adductor brevis, being covered by the Pectineus and Adductor longus, and at the
lower border of the latter muscle communicates with the internal cutaneous and
saphenous nerves, forming a kind of plexus. It then descends upon the femoral
artery, upon which it is finally distributed. The nerve, near the obturator
foramen, gives off an articular branch to the hip-joint. Behind the Pectineus it
distributes muscular branches to the Adductor longus and Gracilis, and usually
to the Adductor brevis, and in rare cases to the Pectineus, and receives a com-
municating branch from the accessory obturator nerve.
Occasionally the communicating branch to the internal cutaneous and saphe-
nous nerves is continued down, as a cutaneous branch (ramus cutaneus], to the
thigh and leg. When this is so, this occasional cutaneous branch emerges from
beneath the lower border of the Adductor longus, descends along the posterior
margin of the Sartorius to the inner side of the knee, where it pierces the deep
fascia, communicates with the long saphenous nerve, and is distributed to the
integument of the inner side of the leg as low down as its middle. When this
communicating branch is small its place is supplied by the internal cutaneous
nerve.
The Posterior Branch (ramus posterior) pierces the Obturator externus, sending
branches to supply it, and passes behind the Adductor brevis on the front of the
Adductor magnus, where it divides into numerous muscular branches, which
supply the Adductor magnus, and the Adductor brevis when the latter does not
receive a branch from the anterior division of the nerve. One of the branches
gives off a filament to the knee-joint.
The Articular Branch for the Knee-joint is sometimes absent; it perforates the
lower part of the Adductor magnus, and enters the popliteal space; it then
descends upon the popliteal artery, as far as the back part of the knee-joint,
where it perforates the posterior ligament, and is distributed to the synovial
membrane. It gives filaments to the popliteal artery in its course.
The Accessory Obturator Nerve or the Accessory Anterior Femoral Nerve of Winslow
(n. obturatorius accessorius (Fig. 675). — The accessory obturator nerve is not con-
stantly present. It is of small size, and arises by separate filaments from the
third and fourth lumbar nerves. It descends along the inner border of the Psoas
muscle, crosses the ascending ramus of the os pubis, and passes under the outer
border of the Pectineus muscle, where it divides into numerous branches. One
of these supplies the Pectineus, penetrating its under surface; another is dis-
tributed to the hip-joint; while a third communicates with the anterior branch of
the obturator nerve. When this nerve is absent the hip-joint receives two branches
from the obturator nerve. Occasionally the articular branch is very small, and
becomes lost in the capsule of the hip-joint.
THE LUMBAR PLEXUS 1021
The Femoral or Anterior Crural Nerve (n. femoralis) (Figs. 669, 670, and 672). —
The femoral nerve is the largest branch of the lumbar plexus. It supplies
muscular branches to the Iliacus, Pectineus, and all the muscles on the front
of the thigh, excepting the Tensor fasciae femoris; cutaneous filaments to the
front and inner side of the thigh, and to the leg and foot (Fig. 667); and
articular branches to the hip and knee. It arises from the second, third, and
fourth lumbar nerves, sometimes from the first or fifth as well. It descends
through the fibres of the Psoas muscle, emerging from this muscle at the lower
part of its outer border, and passes caudad between it and the Iliacus muscle, and
beneath Poupart's ligament, into the thigh, where it becomes somewhat flattened,
and divides into an anterior and a posterior part. Under Poupart's ligament it
is separated from the femoral artery by a portion of the Psoas muscle, and lies
beneath the iliac fascia.
Within the abdomen the femoral nerve gives off from its outer side some small
muscular branches to the Iliacus, and a branch to the femoral artery which is
distributed upon the upper part of that vessel. The origin of this branch varies;
it occasionally arises higher than usual, or it may arise lower down in the thigh.
External to the pelvis the following branches are given off :
From the Anterior Division. From the Posterior Division.
Middle cutaneous. Long saphenous.
Internal cutaneous. Muscular.
Muscular. Articular.
The middle and internal cutaneous branches of the femoral nerve are the
rami cutanei anteriores n. femoralis of the new nomenclature.
The Middle Cutaneous Nerve (Figs. 671 and 672) pierces the fascia lata (generally
the Sartorius muscle also) about three inches (8 cm.) below Poupart's ligament, and
divides into two branches (Fig. 671), which descends in immediate proximity along
the forepart of the thigh, to supply the integument as low as the front of the knee,
where it communicates with the internal cutaneous nerve and the patellar branch
of the saphenous nerve, to form the patellar plexus. In the upper part of the thigh
the outer division of the middle cutaneous nerve communicates with the femoral
branch of the genito-femoral nerve.
The Internal Cutaneous Nerve (Fig. 671) passes obliquely across the upper part
of the sheath of the femoral artery, and divides in front or at the inner side of that
vessel into two branches, anterior and posterior or internal.
The anterior branch runs caudad on the Sartorius, perforates the fascia lata
at the lower third of the thigh, and divides into two branches, one of which sup-
plies the integument as low down as the inner side of the knee; the other crosses
to the outer side of the patella, communicating in its course with the nervus
cutaneus patellae, a branch of the saphenous nerve.
The posterior or internal branch descends along the inner border of the Sartorius
muscle to the knee, where it pierces the fascia lata, communicates with the long
saphenous nerve, and gives off several cutaneous branches. The nerve then
passes down the inner side of the leg, to the integument of which it is distributed.
This nerve, beneath the fascia lata, at the lower border of the Adductor longus,
joins in a plexiform network by uniting with branches of the saphenous and
obturator nerves (Fig. 672). When the communicating branch from the obturator
nerve is large and continued to the integument of the leg, the inner branch of the
internal cutaneous is small and terminates at the plexus, occasionally giving off
a few cutaneous filaments.
The internal cutaneous nerve, before dividing, gives off a few filaments, which
pierce the fascia lata, to supply the integument of the inner side of the thigh.
1022 THE NERVE SYSTEM
One of these filaments passes through the saphenous opening; a second becomes
subcutaneous about the middle of the thigh (Fig. 671); and a third pierces the
fascia at its lower third (Fig. 671).
The Muscular Branches of the Anterior Division (rami musculares). — The nerve
to the Pectineus is often duplicated; it arises from the femoral nerve immediately
below Poupart's ligament, and passes inward behind the femoral sheath to enter
the anterior surface of the muscle. The nerve to the Sartorius arises in common
with the middle cutaneous.
The Saphenous, Long Saphenous or Internal Saphenous Nerve (n. saphenus]
(Figs. 671 and 672) is the largest of the cutaneous branches of the femoral nerve.
It approaches the femoral artery where this vessel passes beneath the Sartorius,
and lies ventrad of it, beneath the aponeurotic covering of Hunter's canal, as far
as the opening in the lower part of the Adductor magnus. It then leaves the
artery, and proceeds distally along the inner side of the knee, beneath the Sartorius
muscle, pierces the fascia lata opposite the interval between the tendons of the
Sartorius and Gracilis muscles, and becomes subcutaneous. The nerve then
passes along the inner side of the leg (Fig. 671), accompanied by the internal
saphenous vein, descends behind the internal border of the tibia, and, at the
lower third of the leg, divides into two branches : one continues its course along the
margin of the tibia, terminating at the inner ankle; the other passes in front of
the ankle, and is distributed to the integument along the inner side of the foot, as
far as the great toe, communicating with the internal branch of the musculo-
cutaneous nerve.
The saphenous nerve about the middle of the thigh gives off a communicating
branch which joins the plexus formed by the obturator and internal cutaneous
nerves.
At the inner side of the knee it gives off a large patellar branch, the nervus
cutaneus patellae (ramus infrapatellaris] , which pierces the Sartorius and fascia
lata, and is distributed to the integument in front of the patella. This nerve com-
municates above the knee with the anterior branch of the internal cutaneous and
with the middle cutaneous; below the knee, with other branches of the saphenous;
and on the outer side of the joint, with branches of the external cutaneous nerve,
forming a plexiform network, the patella plexus (plexus patellae). The cutaneous
nerve of the patella is occasionally small, and terminates by joining the internal
cutaneous, which supplies its place in front of the knee.
Below the knee the branches of the saphenous nerves are distributed to the
integument of the front and inner side of the leg, communicating with the cuta-
neous branches from the internal cutaneous or from the obturator nerve. The
nerve also sends filaments to the ankle-joint.
The Muscular Branches of the Posterior Division. — The muscular branches of the
posterior division supply the four parts of the Quadriceps extensor muscle.
The branch to the Rectus muscle enters its under surface high up, sending off a
small filament to the hip-joint.
The branch to the Vastus externus muscle, of large size, follows the course of
the descending branch of the external circumflex artery to the lower part of the
muscle. It gives off an articular filament to the knee-joint.
The branch to the Vastus internus muscle is a long branch which runs down
on the outer side of the femoral vessels in company with the saphenous nerve
for its upper part. It enters the muscle about its middle, and gives off a fila-
ment which can usually be traced caudad on the surface of the muscle to the
knee-joint.
The branch to the Crureus muscle enters the muscle on its anterior surface
about the middle of the thigh, and sends a filament through the muscle to the
Subcrureus and the knee-joint.
THE DORSAL DIVISIONS OF THE SACRAL NERVES 1Q23
The articular branch to the hip-joint is derived from the nerve to the Rectus
muscle.
The articular branches to the knee-joint are three in number. One, a long, slender
filament, is derived from the nerve to the Vastus extern us muscle; it penetrates the
capsular ligament of the joint on its anterior aspect. Another is derived from
the nerve to the Vastus internus muscle. It can usually be traced downward
on the surface of this muscle to near the joint; it then penetrates the muscle
and accompanies the deep branch of the ariastomotica magna artery, pierces the
capsular ligament of the joint on its inner side, and supplies the synovial
membrane. The third branch is derived from the nerve to the Crureus.
THE SACRAL AND COCCYGEAL NERVES (NN. SACRALES ET COGGYGEUS).
The sacral nerves are five in number on each side. The four upper ones pass
from the sacral canal through the sacral foramina; the fifth through the foramen
between the sacrum and coccyx.
The Roots of the Upper Sacral Nerves.
The roots of the upper sacral nerves are the largest of all the spinal nerves;
while those of the lower sacral and the coccygeal nerve are the smallest. They are
longer than those of any of the other spinal nerves, on account of the spinal cord
' not extending beyond the first lumbar vertebra. From their great length, and the
appearance they present in connection with their attachment to the spinal cord,
the roots of origin of these nerves are called collectively the cauda equina.
Each sacral and coccygeal nerve separates into two divisions, dorsal and
ventral.
The Dorsal Divisions of the Sacral Nerves (Rami Posteriores) (Fig. 673).
The dorsal divisions of the sacral nerves are small, diminish in size from above
caudad, and emerge, except the last, from the sacral canal by the dorsal sacral
foramina.
The Upper Sacral Nerves. — Each of the three upper ones is covered, at its
exit from the sacral canal, by the Multifidus spinse muscle, and divides into a
medial branch and a lateral branch.
The Medial Branches (ramus medialis). — The medial branches are small, and
supply the Multifidus spinse muscle.
The Lateral Branches (ramus later alls'). — The lateral branches join with one
another, and with the last lumbar and fourth sacral nerves, in the form of loops on
the dorsal surface of the sacrum, constituting the dorsal sacral plexus. From these
loops branches pass to the outer surface of the great sacro-ischiatic ligament, where
they form a second series of loops beneath the Gluteus maximus muscle. Cuta-
neous branches from this second series of loops, usually two or three in number,
pierce the Gluteus maximus muscle along a line drawn from the posterior superior
spine of the ilium to the tip of the coccyx. They supply the integument over the
dorsal part of the gluteal region.
The Lower Sacral Nerves. — The dorsal divisions of the two lower sacral
nerves are situated below the Multifidus spinae muscle. They are of small size,
and do not divide into medial and lateral branches, but join with each other,
and with the dorsal division of the coccygeal nerve to form the dorsal sacro-
coccygeal nerve, which passes through the sacro-sciatic ligament, and forms loops
on the back of the sacrum, filaments from which supply the Extensor coccygeus
and the integument over the coccyx.
1024
THE NERVE SYSTEM
FIG. 673. — The posterior sacral nerves.
Femoral artery.
Coccygeal.
'Br. to' Br. to
LEVATOH ANI. SPHINCTER ANI
FIG. 674. — Side view of pelvis, showing sacral nerves.
Br. to
COCCYGEUS.
THE VENTRAL DIVISION OF THE COCCYGEAL NERVE 1Q25
The Ventral Divisions of the Sacral Nerves (Rami Anteriores) (Fig. 675).
The ventral divisions of the sacral nerves diminish in size from above down-
ward. The four upper ones emerge from the anterior sacral foramina; the ventral
division of the fifth, after emerging from the vertebral canal through its terminal
opening, curves forward between the sacrum and the coccyx. All the ventral
sacral nerves at their exit from the sacral foramina communicate with the sacral
ganglia of the sympathetic. The first nerve (Fig. 674), of large size, unites with
the lumbo-sacral cord (truncus lumbosacralis), formed by the fifth lumbar, and a
branch from the fourth lumbar (n. furcalis). The second (Fig. 674), equal in
size to the preceding, and the third (n. bigeminus) (Fig. 674), about one-fourth
the size of the second, unite with this trunk, and form, with a small fasciculus
from the fourth, the sacral plexus, a visceral branch being given off from the third
nerve to the bladder (Fig. 675).
The Fourth Ventral Sacral Nerve sends a branch to join the sacral plexus. The
remaining portion of the nerve divides into visceral and muscular branches, and a
communicating filament descends to join the fifth sacral nerve.
The visceral branches are distributed to the viscera of the pelvis, communicating
with the sympathetic nerve. These branches ascend upon the rectum and bladder,
and in the female upon the vagina, communicating with branches of the sym-
pathetic from the pelvic plexus. The visceral branches of the third and fourth
sacral do not join the gangliated cord.
The muscular branches are distributed to the Levator ani, Coccygeus, and
Sphincter ani. The branch to the Sphincter ani pierces the Levator ani, so as to
reach the ischio-rectal fossa, where it is found lying in front of the coccyx. Cuta-
neous filaments arise from the latter branch, which supply the integument between
the anus and coccyx. Another cutaneous branch is frequently given off from this
nerve, though sometimes from the pudic (Schwalbe). It perforates the great
sacro-sciatic ligament, and, winding around the lower border of the Gluteus
maximus, supplies the skin over the lower and inner part of this muscle.
The Fifth Ventral Sacral Nerve, after passing from the lower end of the sacral
canal, curves forward through the fifth sacral foramen, formed between the lower
part of the sacrum and the transverse process of the first piece of the coccyx. It
pierces the Coccygeus muscle, and descends upon its anterior surface to near the
tip of the coccyx, where it again perforates the muscle, to be distributed to the
integument over the back part and side of the coccyx. This nerve communicates
above with the fourth sacral and below with the coccygeal nerve, and supplies the
Coccygeus muscle.
The Dorsal Division of the Coccygeal Nerve.
The coccygeal nerve divides into its ventral and dorsal divisions in the vertebral
canal. The dorsal division is the smaller. It does not divide, but receives, as
already mentioned, a communicating branch from the last sacral, and is lost
in the integument over the back of the coccyx.
The Ventral Division of the Coccygeal Nerve.
The ventral division of the coccygeal nerve is a delicate filament which escapes
at the termination of the sacral canal; it passes caudad behind the rudimentary
transverse process of the first piece of the coccyx, and curves ventrad through
the notch between the first and second pieces, piercing the Coccygeus muscle and
descending on its ventral surface to near the tip of the coccyx, wrhere it again
65
1026
THE NERVE SYSTEM
pierces the muscle, to be distributed to the integument over the back part and side
of the coccyx. It is joined by a branch from the fifth ventral sacral as it descends
on the surface of the Coccygeus muscle.
The Pudendal Plexus (plexus pudendus). — The pudendal plexus is formed by
fibres obtained from the ventral divisions of the first three sacral nerves and by
the ventral divisions of the two lower sacral nerves and the coccygeal nerve. It
is, so to speak, interpolated in the sacral plexus and is considered as a portion of it.
The Sacral or Sciatic Plexus (Plexus Sacralis) and the Pudic or Pudendal
Plexus (Plexus Pudendalis) (Fig. 675).
The sacral plexus is formed by the lumbo-sacral cord, the ventral divisions
of the three upper sacral nerves, and a branch from the fourth. The pudic or
pudendal plexus is considered with the sacral plexus. It is usually composed
FOURTH LUMBAR
FIFTH LUMBAR
FIRST SACRAL
SECOND SACRAL
THIRD SACRAL
FOURTH SACRAL
PERINEAL BR. TO SPHINCTER
LEVATOR ANI
,', FIFTH SACRAL
N.TOCOCCYGEUS
,y-— ^COCCYGEAL
/?
SCIATICA
FIG. 675. — Plan of sacral plexus with the pudendal plexus. (Gerrish.)
of the ventral divisions of the second, third, fourth and fifth sacral nerves and
the coccygeal nerve. It is irregular in composition. Prof. Cunningham says:
"There is no distinct point of separation between the two plexuses. On the con-
trary, there is considerable overlapping, so that two and sometimes three of the
principal nerves derived from the pudendal plexus have their origin in common
with nerves of the sacral plexus." The nerves of these two plexuses proceed in
different directions: the upper ones obliquely caudad and outward, the lower
ones nearly horizontally outward, and they all unite into two cords; an upper and
larger cord, which is formed by the lumbo-sacral cord with the first, second, and
the greater part of the third sacral nerves; and a lower and smaller cord, formed
by the remainder of the third, with a portion of the fourth sacral nerve. The
upper cord is prolonged into the great sciatic nerve and the lower into the pudic.
Frequently a small filament is given off from the second sacral nerve to join the
lower cord.
THE SACRAL OR SCIATIC PLEXUS 1027
Each of the nerves which form the plexus joins the sympathetic by gray rami
communicantes. White rami communicantes join the third sacral and sometimes
also the second and fourth sacrals to the sympathetic.
The sacro-pudendal plexus is triangular in form, its base corresponding with
the exit of the nerves from the sacrum, its apex with the lower part of the great
sacro-sciatic foramen. It rests upon the anterior or ventral surface of the Pyri-
formis, and is covered ventrad by the pelvic fascia, which separates it from the
sciatic and pudic branches of the internal iliac artery and from the viscera of the
pelvis. The sacral plexus proper sends branches to the lower extremity; the
pudendal plexus proper is largely limited to supplying the perineum.
Branches. — The branches of the sacro-pudendal plexus are divided into col-
lateral and terminal branches.
Muscular.
Superior gluteal.
Collateral branches •{ Inferior gluteal.
I Small sciatic.
I Perforating cutaneous.
Terminal branches {
The Muscular Branches (rami musculares). — The muscular branches supply the .
Pyriformis, Obturator internus, the two Gemelli and the Quadratus femoris.
The branch to the Pyriformis muscle arises from the upper two sacral nerves
before they enter the plexus; the branch to the Obturator internus muscle arises
at the junction of the lumbo-sacral and first sacral nerves; it passes out of the pelvis
through the great sacro-sciatic foramen below the Pyriformis, crosses the spine
of the ischium, and re-enters the pelvis through the lesser sacro-sciatic foramen
to enter the inner surface of the Obturator internus; the branch to the Gemellus
superior muscle arises in common with the nerve to the Obturator internus
muscle; it enters the muscle at the upper part of its dorsal surface; the small
branch to the Gemellus inferior and Quadratus femoris muscles also arises from
the upper part of the plexus; it passes through the great sacro-sciatic foramen
below the Pyriformis, and courses down beneath the great sciatic nerve, the Gemelli
and tendon of the Obturator internus, supplies the muscles on their deep or
ventral surface, and gives off an articular branch to the hip-joint. A second
articular branch is occasionally derived from the upper part of the sacral plexus.
The Superior Gluteal Nerve (n. glutaeus superior) (Figs. 675 and 677). — The
superior gluteal nerve arises from the back part of the lumbo-sacral cord, with
some filaments from the first sacral nerve; it passes from the pelvis through the
great sacro-sciatic foramen above the Pyriformis muscle, accompanied by the
gluteal vessels, and divides into a superior and an inferior branch.
The Superior Branch follows the line of origin of the Gluteus minimus, and
supplies the Gluteus medius muscle.
The Inferior Branch crosses obliquely between the Gluteus minimus and medius,
distributing filaments to both these muscles, and terminates in the Tensor fasciae
femoris muscle, extending nearly to its lower end.
The Inferior Gluteal Nerve (n. glutaeus inferior) (Fig. 675).— The inferior gluteal
nerve arises from the lumbo-sacral cord and first and second sacral nerves, and is
intimately connected with the small sciatic at its origin. It passes out of the pelvis
through the great sciatic notch, beneath the Pyriformis muscle, and, dividing into
a number of branches, enters the Gluteus maximus muscle on its under surface.
The Small Sciatic Nerve (n. cutaneus femoris posterior] (Figs. 675, 676, and 677).
—The small sciatic or postfemoral cutaneous nerve supplies the integument of the
perineum and back part of the thigh and leg. It is usually formed by the union of
1028 THE NERVE SYSTEM
two branches, which arise from the second and third nerves of the sacral plexus.
It issues from the pelvis through the great sacro-sciatic foramen below the Pyrifor-
mis muscle, descends beneath the Gluteus maximus with the sciatic artery, and at
the lower border of that muscle passes along the back part of the thigh, beneath the
fascia lata and over the long head of the Biceps, to the lower part of the popliteal
region, where it pierces the fascia and becomes cutaneous. It then accompanies
the external saphenous vein (v. saphena parva) to about the middle of the leg, its
terminal filaments communicating with the sural or external saphenous nerve.
The Branches of the small sciatic nerve are all cutaneous, and are grouped as
follows : gluteal, perineal, and femoral.
The Gluteal Cutaneous Branches (nn. clunium inferiores [laterales]) consist of two
or three ascending filaments, which turn upward around the lower border of the
Gluteus maximus to supply the integument covering the lower and outer part of
that muscle.
The Perineal Cutaneous Branches (rami perineales] are distributed to the skin at
the upper and inner side of the thigh, on its posterior aspect. One branch, longer
than the rest, the inferior pudendal or long scrotal nerve (Fig. 677), curves forward
below the tuber ischii, pierces the fascia lata, and passes forward beneath the
superficial fascia of the perineum to be distributed to the integument of the scrotum
in the male and the labium in the female, communicating with the superficial
perineal and inferior hemorrhoidal nerves.
The Femoral Cutaneous Branches are numerous descending filaments, derived
from both sides of the nerves, which are distributed to the back, inner, and outer
sides of the thigh, to the skin covering the popliteal space, and to the upper part
of the leg.
The Perforating Cutaneous Nerve (n. clunium inferior medialis) (Fig. 675). — The
perforating cutaneous nerve usually arises from the second and third sacral nerves,
and is of small size. It is continued dorsad through the great sacro-sciatic ligament,
and, winding around the lower border of the Gluteus maximus, supplies the integu-
ment covering the inner and lower part of that muscle.
The Pudic Nerve (n. pudendus} (Figs. 675 and 677). — The pudic nerve is the
direct continuation of the lower cord of the sacral plexus, and derives its fibres
from the third and fourth sacral nerves, and frequently from the second also. It
leaves the pelvis through the great sacro-sciatic foramen, below the Pyriformis.
It then crosses the spine of the ischium, and re-enters the pelvis through the lesser
sacro-sciatic foramen. It accompanies the pudic vessels upward and forward
along the outer wall of the ischio-rectal fossa, being contained in a sheath of the
obturator fascia, termed Alcock's canal, and divides into two terminal branches,
the perineal nerve and the dorsal nerve of the penis or clitoris. Before its division it
gives off the inferior hemorrhoidal nerve.
The Inferior Hemorrhoidal Nerve (n. hcemorrhoidalis inferior} is occasionally
derived separately from the sacral plexus. It passes across the ischio-rectal fossa,
with its accompanying vessels, toward the lower end of the rectum, and is dis-
tributed to the Sphincter ani externus and to the integument around the anus.
Branches of this nerve communicate with the inferior pudendal and superficial
perineal nerves at the forepart of the perineum.
The Perineal Nerve (n. perinei], the inferior and larger of the two terminal
branches of the pudic, is situated below the pudic artery. It accompanies the
superficial perineal artery in the perineum, dividing into cutaneous and muscular
branches.
The cutaneous branches (superficial perineal) are two in number, posterior and
anterior. The posterior or external branch pierces the base of the triangular liga-
ment of the urethra, and passes forward along the outer side of the urethral
triangle in company with the superficial perineal artery; it is distributed to the
THE SACRAL OR SCIATIC PLEXUS
1029
A
\
Superior
gluteal.
PuiUc.r
Nerve to
obturator ihternus.
Small sciatic. •
Inferior _5tf
pudendal.
Descending
cutaneous.
Internal
popliteal*
External
-popliteal, or
common
peroneaL
Sural or
external .
saphenous.
Posterior
tibial.
Plantar,
cutaneous.
Communicant
peronei.
FIG. 676. — Cutaneous nerves of lower
extremity. Posterior view.
FIG. 677. — Nerves of the lower extremity.1
Posterior view.
1 N. B. — In this diagram the external saphenous (or sural nerve) and eommunicans peronei are not in their
normal position. They have been displaced by the removal of the superficial muscles.
1030 THE NERVE SYSTEM
skin of the scrotum (nn. scrotales posteriores). It communicates with the inferior
hemorrhoidal, the inferior pudenda!, and the other superficial perineal nerve.
The anterior or internal branch also pierces the base of the triangular ligament, and
passes forward nearer to the middle line, to be distributed to the inner and back
part of the scrotum. Both these nerves supply the labia majora in the female.
The muscular branches are distributed to the Transversus perinaei, Accelerator
urinae, Erector penis, and Compressor urethrae. A distant branch is given off
from the nerve to the Accelerator urinae, which pierces this muscle, and supplies
the corpus spongiosum, ending in the mucous membrane of the urethra. This
is the nerve to the bulb.
The Dorsal Nerve of the Penis (n. dorsalis penis') is the deepest division of the
pudic nerve; it accompanies the pudic artery along the ramus of the ischium; it
then runs forward along the inner margin of the ramus of the os pubis, between
the superficial and deep layers of the triangular ligament. Piercing the superficial
layer it gives a branch to the corpus cavernosum, and passes forward, in company
with the dorsal artery of the penis, between the layers of the suspensory ligament,
on to the dorsum of the penis, along which it is carried as far as the glans, to which
it is distributed.
In the female the dorsal nerve is very small, and supplies the clitoris (n. dorsalis
clitoridis}.
The Great Sciatic Nerve (n. iscliiadicus) (Figs. 675 and 677) . — The great sciatic
nerve supplies nearly the whole of the integument of the leg, the muscles of the
back of the thigh, and those of the leg and foot. It is the largest nerve cord in the
body, measuring three-quarters of an inch in breadth, and is the direct continuation
of the upper division of the sacral plexus. It passes out of the pelvis through the
great sacro-sciatic foramen, below the Pyriformis muscle. It descends between
the trochanter major and tuberosity of the ischium, along the back part of the
thigh, to about its lower third, where it divides into two large branches, the internal
or tibial and external popliteal or peroneal nerves (Fig. 677).
This division may take place at any point between the sacral plexus and the
lower third of the thigh. When the division occurs at the plexus (in 10 per cent, of
cases) the two nerves descend together side by side; or they may be separated, at
their commencement, by the interposition of part or the whole of the Pyriformis
muscle. As the nerve descends along the back of the thigh, it rests upon the
dorsal surface of the ischium, the nerve of the Quadratus femoris, and the External
rotator muscles, in company with the small sciatic nerve and artery, being covered
by the Gluteus maximus; lower down, it lies upon the Adductor magnus, and is
covered by the long head of the Biceps. The great sciatic, even when apparently
a single nerve, is really two nerves appearing as one.
Branches. — The branches of the nerve, before its division, are articular and
muscular.
The Articular Branches (mini articulares] arise from the upper part of the nerve;
they supply the hip-joint, perforating the posterior part of its fibrous capsule.
These branches are sometimes derived from the sacral plexus.
The Muscular Branches (rami musculares) are distributed to the flexors of the leg
— viz., the Biceps, Semitendinosus, and Semimembranosus, and a branch goes to
the Adductor magnus. These branches are given off beneath the Biceps muscle.
The Internal Popliteal or Tibial Nerve (n.tibialis) (Figs. 675 and 677), in reality,
arises from the fourth and fifth lumbar nerves and the first three sacral nerves, and
becomes a part of the trunk of the great sciatic in the buttock, to emerge from it
again at the bifurcation of the sciatic. It is the larger of the two terminal branches
of the great sciatic, descends along the back part of the thigh, through the middle of
the popliteal space, to the lower part of the Popliteus muscle, where it passes with
the arterv beneath the arch of the Soleus and becomes the posttibial. It is over-
THE SACRAL OR SCIATIC PLEXUS 1031
lapped by the hamstring muscles above, and then becomes more superficial, and
lies to the outer side of, and some distance from, the popliteal vessels; opposite
the knee-joint it is in close relation with the vessels, and crosses to the inner side of
the artery. Below, it is overlapped by the Gastrocnemius muscle.
The branches of this nerve are — articular, muscular, and a cutaneous branch, the
communicating tibial nerve.
The articular branches (rami articulares), usually three in number, supply the
knee-joint; two of these branches accompany the superior and inferior internal
articular arteries, and a third, the azygos articular artery.
The muscular branches (rami m,usculares), four or five in number, arise from the
nerve as it lies between the two heads of the Gastrocnemius muscle; they supply
that muscle, and the Plantaris, Soleus, and Popliteus. The filaments which
supply the Popliteus turn around its lower border and are distributed to its deep
surface.
The tibial communicating nerve (n. cutaneus surae medialis) is the cutaneous
branch. It descends between the two heads of the Gastrocnemius muscle, and
about the middle of the back of the leg pierces the deep fascia, and joins the
peroneal or fibular communicating nerve (ramus anastomoticus peronaeus) from the
external popliteal nerve to form the sural nerve (external or short saphenous) (Fig.
677). The sural nerve, formed by the communicating branches of the internal and
external popliteal nerves, passes downward and outward near the outer margin of
the tendo Achillis, lying close to the small saphenous vein, to the interval between
the external malleolus and the os calcis. It divides in two branches, the posterior
of which breaks up into lateral calcaneal branches (rami calcanei laterales). The
anterior branch (n. cutaneus dorsalis lateralis) winds around the outer malleolus,
and is distributed to the integument along the outer side of the foot and little toe,
communicating on the dorsum of the foot with the musculo-cutaneous nerve. In
the leg its branches communicate with those of the small sciatic. The cutaneous
area supplied by the sural nerve is indicated in Fig. 679.
The Posttibial Nerve (Fig. 677) is the terminal portion of the internal pop-
liteal nerve. It commences at the lower border of the Popliteus muscle, and
passes along the back part of the leg with the posterior tibial vessels to the interval
between the inner malleolus and the heel, where it divides into the external and
internal plantar nerves. It lies upon the deep muscles of the leg, and is covered in
the upper part by the muscles of the calf, lower down by the skin and fascia. In
the upper part of its course it lies to the inner side of the posterior tibial artery, but
it soon crosses that vessel, and lies to its outer side as far as the ankle. In the lower
third of the leg it is placed parallel with the inner margin of the tendo Achillis.
The branches of the posttibial nerve are muscular, medial or internal calcaneal or
calcaneo-plantar, and articular.
The muscular branches (rami musculares) arise either separately or by a common
trunk from the upper part of the nerve. They supply the Soleus, Tibialis posticus,
Flexor longus digitorum, and Flexor longus hallucis muscles; the branch to the
latter muscle accompanying the peroneal artery. The branch to the Soleus enters
its deep surface, while the branch which this muscle receives from the internal
popliteal enters its superficial aspect.
The medial or internal calcaneal or calcaneo-plantar branches (rami calcanei
mediates) perforate the internal annular ligament, and supply the integument of
the heel and inner side of the foot (Fig. 679).
The articular branch (ramus articularis ad articulation em talocruralem) is given
off just above the bifurcation of the nerve and supplies the ankle-joint.
The Medial or Internal Plantar Nerve (n. plantaris medialis} (Fig. 678), the larger
of the two terminal branches of the posttibial, accompanies the medial plantar
artery along the inner side of the foot. From its origin at the inner ankle it passes
1032
THE NERVE SYSTEM
beneath the Abductor hallucis, and divides into the common plantar digital nerves
(nn. digitales plantares communes), which pass distad between the Abductor
hallucis and the Flexor brevis digitorum, dividing opposite the bases of the metatar-
sal bones into four collateral plantar digital branches, and communicating with the
lateral plantar nerve.
In its course the medial plantar nerve gives off cutaneous branches, which pierce
the plantar fascia and supply the integument of the sole of the foot (Fig. 679);
muscular branches, which supply the Abductor hallucis and Flexor brevis digitorum;
articular branches, to the articulations of the tarsus and metatarsus; and four col-
lateral plantar digital branches (nn. digitales plantares proprii). The three outer
branches pass between the divisions of the plantar fascia in the clefts between the
toes; the first (innermost) branch becomes
cutaneous more proximally between the Ad-
ductor hallucis and Flexor brevis digitorum.
They are distributed in the following man-
ner: The first supplies the inner border of
the great toe, and sends a filament to the
Flexor brevis hallucis muscle; the second
bifurcates, to supply the adjacent sides of
Medial
or
Internal
plantar
Lateral
or
External
plantar
Deep
branch.
FIG. 678. — The plantar nerves.
FIG. 679. — Areas of distribution of the cutaneous nerves of
the sole. (W. Keiller, in Gerrish's Text-book of Anatomy.)
the great and second toes, sending a filament to the First lumbrical muscle; the
third supplies the adjacent sides of the second and third toes; the fourth supplies
the corresponding sides of the third and fourth toes, and receives a communicating
branch from the external plantar nerve (Fig. 679). Each digital nerve gives off
cutaneous and articular filaments; and opposite the last phalanx sends a dorsal
branch, which supplies the structures around the nail, the continuation of the nerve
being distributed to the ball of the toe. It will be observed that the distribution
of these branches is precisely similar to that of the median nerve in the hand.
The Lateral or External Plantar Nerve (n. plantar is lateralis) (Fig. 678), the smaller
of the two, completes the nerve supply to the structures of the sole of the foot
(Fig. 679), being distributed to the little toe, and one-half of the fourth, as well as
to most of the deep muscles, its distribution being similar to that of the ulnar in the
hand. It passes obliquely distad with the lateral plantar artery to the outer side of
the foot, lying between the Flexor brevis digitorum and Flexor accessorius, and in
the interval between the former muscle and Abductor minimi digiti divides into a
THE SACRAL OR WIA'IIC PLEXUS 1033
superficial and a deep branch. Before its division it supplies the Flexor accessorius
and Abductor minimi digiti.
The superficial branch (minus superficialis) separates into two digital nerves.
Before division they are called common plantar digital nerves (nn. digitales plantares
communes), after division the collateral plantar digital nerves (nn. digitales plantares
proprii): one, the external branch, the smaller of the two, supplies the outer side of
the little toe, the Flexor brevis minimi digiti, and the two Interosseous muscles of
the fourth metatarsal space; the other and larger digital branch supplies the
adjoining sides of the fourth and fifth toes, and communicates with the medial
plantar nerve.
The deep or muscular branch (ramus profundus) accompanies the lateral plantar
artery into the deep part of the sole of the foot, beneath the tendons of the Flexor
muscles and Adductor obliquus hallucis, and supplies all the Interossei (except
those in the fourth metatarsal space), the three outer Lumbricales, the Adductor
obliquus hallucis, and the Adductor transversus hallucis.
The External Popliteal or Common Peroneal Nerve (n. peronaeus communis) (Figs.
675 and 677) in reality arises from the fourth and fifth lumbar and the first and
second sacral nerves. It is about one-half the size of the internal popliteal, descends
obliquely along the outer sides of the popliteal space to the head of the fibula, close
to the inner margin of the Biceps muscle. It is easily felt beneath the skin behind
the head of the fibula at the inner side of the tendon of the Biceps. It passes
between the tendon of the Biceps and outer head of the Gastrocnemius muscle,
winds around the neck of the fibula, between the Peroneus longus and the bone,
and divides beneath the muscle into the deep peroneal (anterior tibial) and musculo-
cutaneous nerves.
The branches of the peroneal nerve, previous to its division, are articular and
cutaneous.
The articular branches (rami articulares) are three in number: two of these accom-
pany the superior and inferior lateral articular arteries to the outer side of the knee.
The upper one occasionally arises from the great sciatic nerve before its bifurcation.
The third (recurrent} articular nerve is given off at the point of division of the
peroneal nerve; it ascends with the anterior recurrent tibial artery through the
Tibialis anticus muscle to the front of the knee, which it supplies.
The Sural or Lateral Cutaneous Branch (n. cutaneus surae lateralis). — There may
be two or three of these branches. They supply the integument along the back
part and outer side of the leg. The largest cutaneous branch of the peroneal is the
peroneal communicating (ramus anastomoticus peronaeus or communicans fibularis),
arises near the head of the fibula, crosses the external head of the Gastrocnemius
to the middle of the leg, and joins with the communicans tibialis to form the
external saphenous. This nerve occasionally exists as a separate branch, which is
continued as far down as the heel.
The Deep Peroneal or Anterior Tibial Nerve (n. peronaeus profundus) (Fig. 672)
commences at the bifurcation of the peroneal nerve, between the fibula and upper
part of the Peroneus longus muscle, passes obliquely distad beneath the Extensor
longus digitorum muscle to the forepart of the interosseous membrane, and
gets into relation with the anterior tibial artery above the middle of the leg;
it then descends with the artery to the front of the ankle-joint, where it divides
into an external and an internal branch. This nerve lies at first on the outer side
of the anterior tibial artery, then in front of it, and again at its outer side at the
ankle-joint.
The branches of the anterior tibial nerve in its course through the leg are the
muscular branches (rami musculares) to the Tibialis anticus, Extensor longus digi-
torum, Peroneus tertius, and Extensor proprius hallucis muscles, and an articular
branch to the ankle-joint.
1034 THE NERVE SYSTEM
The external or tarsal branch of the anterior tibial passes outward across the
tarsus, beneath the Extensor brevis digitorum, and, having become enlarged, like
the posterior interosseous nerve at the wrist, supplies the Extensor brevis digitorum
muscle. From the enlargement three minute interosseous branches are given off
which supply the tarsal joints and the metatarso-phalangeal joints of the second,
third, and fourth toes. The first of these sends a filament to the second dorsal
interosseous muscle.
The internal branch, the continuation of the nerve, accompanies the dorsalis
pedis artery along the inner side of the dorsum of the foot, and at the first inter-
osseous space divides into two dorsal digital branches (nn. digitales dorsales hallucis
later alls et digiti secundi medialis), which supply the adjacent sides of the great
and second toes, communicating with the internal branch of the musculo-cutaneous
nerve. Before it divides it gives off an interosseous branch to the first space,
which supplies the metatarso-phalangeal joint of the great toe and sends a fila-
ment to the First dorsal interosseous muscle.
The Musculo-cutaneous Nerve (n. peronaeus superficialis) (Fig. 672) supplies the
muscles on the fibular side of the leg and the integument of the dorsum of the foot.
It passes forward between the Peronei muscles and the Extensor longus digitorum,
pierces the deep fascia at the lower third of the leg on its front and outer side, and
divides into two branches. This nerve in its course between the muscles gives off
muscular branches (rami musculares) to the Peroneus longus and brevis, and cutane-
ous filaments to the integument of the lower part of the leg.
The medial dorsal cutaneous branch (n. cutaneus dorsalis medians') of the musculo-
cutaneous nerve passes in front of the ankle-joint, and divides into two dorsal
digital branches (nn. digitales dorsales pedis), one of which supplies the inner side of
the great toe, the other the adjacent sides of the second and third toes. It also
supplies the integument of the inner ankle and inner side of the foot, communicating
with the saphenous nerve, and joining with the anterior tibial nerve, between the
great and second toes.
The intermediate dorsal cutaneous branch (n. cutaneus dorsalis intermedius] , the
smaller, passes along the outer side of the dorsum of the foot, and divides into two
dorsal digital branches, the inner being distributed to the contiguous sides of the
third and fourth toes, the outer to the opposed sides of the fourth and fifth toes.
It also supplies the integument of the outer ankle and outer side of the foot, com-
municating with the short saphenous nerve.
The branches of the musculo-cutaneous nerve supply all the toes excepting the
outer side of the little toe, which is supplied by the small saphenous nerve. The
adjoining sides of the great toe or second toe are also supplied by the internal
branch of the anterior tibial. It frequently happens that some of the outer branches
of the musculo-cutaneous are absent, their place being then taken by branches of
the small saphenous nerve.
The Coccygeal Plexus.
The coccygeal plexus is a subdivision of the pudendal plexus, formed chiefly by
the anterior division of the fifth sacral nerve, sometimes the fourth also, and the
coccygeal nerve. From this plexus arise the anococcygeal nerves which pierce the
great sacrosciatic ligament and supply the integument over the coccyx.
Surgical Anatomy. — The lumbar plexus passes through the Psoas muscle, and, therefore,
in psoas abscess any or all of its branches may be irritated, causing severe pain in the parts to
which the irritated nerves are distributed. The genito-femoral nerve is the one which is most
frequently implicated. This nerve is also of importance, as it is concerned in one of the reflexes
employed in the investigation of diseases of the spine. If the skin over the inner side of the
thigh just below Poupart's ligament, the part supplied by the femoral branch of the genito-
THE COCCYGEAL PLEXUS 1035
femoral nerve, be gently tickled in a male child, the testicle will be noticed to be drawn upward
through the action of the Cremaster muscle, which is supplied by the genital branch of the
same nerve. The same result may sometimes be noticed in adults, and can almost always be
produced by severe stimulation. This reflex, when present, shows that the portion of the cord
from which the first and second lumbar nerves are derived is in a normal condition.
The femoral or anterior crural nerve is in danger of being injured in fractures of the true pelvis,
since the fracture most commonly takes place through the ascending ramus of the os pubis, at or
near the point where this nerve crosses the bone. It is also liable to be injured in fractures and
(I i. Plications of the femur, and is likely to be pressed upon, and its functions impaired, in some
tumor* growing in the pelvis. Moreover, on account of its superficial position, it is exposed to
injury in wounds and stabs in the groin. When this nerve is paralyzed, the patient is unable to flex
his hip completely, on account of the loss of motion in the Iliacus; or to extend the knee on the
thigh, on account of paralysis of the Quadriceps extensor cruris; there are complete paralysis of
the Sartorius and partial paralysis of the Pectineus. There is loss of sensation down the front and
inner side of the thigh, except in that part supplied by the femoral branch of the genito-femoral
nerve, and by the ilio-inguinal nerve. There is also loss of sensation down the inner side of the
leg and foot as far as the ball of the great toe.
The obturator nerve is of special surgical interest. It is rarely paralyzed alone, but occa-
sionally is paralyzed in association with the femoral. The principal interest attached to it is in
connection with its supply to the knee; pain in the knee being symptomatic of many diseases
in which the trunk of this nerve, or one of its branches, is irritated. Thus it is well known that
in the earlier stages of hip-joint disease the patient does not complain of pain in that articulation,
but on the inner side of the knee, or in the knee-joint itself, both these articulations being sup-
plied by the obturator nerve, the final distribution of the nerve being to the knee-joint. Again,
the same thing occurs in sacro-iliac disease: pain is complained of in the knee-joint or on its
inner side. The obturator nerve is in close relationship with the sacro-iliac articulation, passing
over it, and, according to some anatomists, distributing filaments to it. Again, in cancer of
the rigmoid flexure, and even in cases where masses of hardened faeces are impacted in this
portion of the gut, pain is complained of in the knee. The left obturator nerve lies beneath the
sigmoid flexure, and is readily pressed upon and irritated when disease exists in this part of the
intestine. Finally, pain in the knee forms an important diagnostic sign in obturator hernia.
The hernial protrusion as it passes out through the opening in the obturator membrane presses
upon the nerve and causes pain in the parts supplied by its peripheral filaments. When the
obturator nerve is paralyzed, the patient is unable to press his knees together or to cross one
leg over the other, on account of paralysis of the Adductor muscles. Rotation outward of the
thigh is impaired from paralysis of the Obturator externus. Sometimes there is loss of sensation
in the upper half of the inner side of the thigh.
The great sciatic nerve is liable to be pressed upon by various pelvic tumors, giving rise to
pain along its trunk, to which the term sciatica is applied. Tumors growing from the pelvic
viscera, or bones, aneurisms of some of the branches of the internal iliac artery, calculus in the
bladder when of large size, accumulation of faeces in the rectum, may all cause pressure on the
nerve inside the pelvis, and give rise to sciatica. -Outside the pelvis exposure to cold, violent
movements of the hip-joint, exostoses or other tumors growing from the margin of the sacro-
sciatic foramen, may also give rise to the same condition. When paralyzed there is loss of
motion in all the muscles below the knee, and loss of sensation in the same situation, except the
upper half of the back of the leg, supplied by the small sciatic and the upper half of the inner
side of the leg, when the communicating branch of the obturator is large.
The sciatic nerve has been frequently cut down upon and stretched, or has been acupunctured
for the relief of sciatica. The nerve has also been stretched in cases of locomotor ataxia, the
anaesthesia of leprosy, etc. In order to define it on the surface, a point is taken at the junction
of the middle and lower third of a line stretching from the posterior superior spine of the ilium
to the outer part of the tuber ischii, and a line is drawn from this point to the middle of the upper
part of the popliteal space. The line must be slightly curved with its convexity outward, and as
it passes downward to the lower border of the Gluteus maximus is slightly nearer the tuberosity
of the ischium than to the great trochanter, as it crosses a line drawn between these two points.
The operation of stretching the sciatic nerve is performed by making an incision over the course
of the nerve about the centre of the thigh. The skin, superficial structures, and deep fascia
having been divided, the interval between the inner and outer hamstrings is to be defined, and
these muscles respectively pulled inward and outward with retractors. The nerve will be found a
little to the inner side of the Biceps. It is to be separated from the surrounding structures, hooked
up with the finger, and stretched by steady and continuous traction for two or three minutes.
The sciatic nerve may also be stretched by what is known as the "dry" plan. The patient is
laid on his back, the foot is extended, the leg flexed on the thigh, and the thigh strongly flexed
on the abdomen. While the thigh is maintained in this position the leg is forcibly extended to
its full extent, and the foot as fully flexed on the leg. This last-named method is uncertain.
The position of the external popliteal nerve, close behind the tendon of the Biceps on the outer
side of the ham, should be remembered in subcutaneous division of the tendon. After it is divided,
1036
THE NERVE SYSTEM
a cord often rises up close beside it, which might be mistaken for a small undivided portion of the
tendon, and the surgeon might be tempted to reintroduce his knife and divide it. This must
never be done, as the cord is the external popliteal nerve, which becomes prominent as soon as
the tendon is divided.
THE CRANIAL NERVES (NERVI CEREBRALES).
The irregularities of origin and distribution of the cranial nerves, as compared
with the relatively simple spinal nerves, is so great and their functions were for-
merly so little known that the older anatomists contented themselves with number-
ing them in order, beginning at the cephalic end of the brain, and named
them with reference to their anatomical connections. The enumeration of the
cranial nerves was as variously given, almost, as there were writers upon the
subject ; the systems of Willis and of Sommering were most in vogue for a time,
but the latter prevails to-day. In Sommering's arrangement twelve pairs of cranial
nerves are recognized, but, on morphological and functional grounds, the nerves of
the seventh and eighth pairs should each be considered as being composed of two
nerves, the eleventh pair should be included with the nerves of the tenth, and the
optic "nerve" is rather a diverticulum of the brain itself than a nerve in the strict
sense. Furthermore, while some of the nerves are sensor or motor in a sense
strictly comparable with the spinal nerves, others are "mixed" in function, and
yet others constitute nerves of special sense, lacking general sensibility. The
numerical names, based upon the order in which they pass through the foramina
in the base of the cranium, are being abandoned gradually for the more appro-
priate functional names, »but not yet entirely so. Thus glossopharyngeal has
not yet given way to "gustatory;" "vagus" is shorter than " pneumogastric"-
a term which is misleading for a nerve which is distributed not only to lungs
and stomach, but also to the meninges, the pharynx and oesophagus, larynx and
trachea, heart and pericardium, liver and spleen.
The cranial nerves, as usually enumerated, together with their superficial
"origin" or attachment to the brain and their foramina of exit from the skull, are
tabulated on p. 866. The central olfactory pathway is described on p. 938, and
the central connections of the optic tracts are given on p. 921. The central con-
nections of the remaining cranial nerves are described on pp. 892 to 914.
The following is a brief summary of the twelve pairs of cranial nerves, indicating
their functional nature:
No.
Name.
Functional nature.
I.
Olfactory (fila.)
Smell-sense.
II.
Optic.
Visual -sense.
III.
Oculomotor.
Motor to muscles of eyeball and orbit.
IV.
Trochlear.
Motor to Superior oblique muscles of eyeball.
V.
Trigeminal.
Mixed: Sensor to face, tongue, and teeth;
motor to
muscles of mastication.
VI
Abducent.
Motor to External rectus muscle of eyeball.
VII.
Facial.
Motor to muscles of scalp and face.
Nervus intermedius.
Mixed: Sensor (gustatory) to tongue; excito-glandular
to submaxillary and sublingual salivary glan
ds.
VIII.
Acoustic:
I. Cochlearis.
Hearing-sense.
II. Vestibularis.
Equilibratory-sense.
IX.
Glossopharyngeal.
• Mixed: Sensor (and gustatory) to tongue and
pharynx ;
motor (?) to Stylopharyngeus muscle.
X.
Vagus.
Mixed: Sensori-motor to respiratory tract and part of
alimentary tract.
XI.
Accessory.
I. Accessory to vagus.
Motor to muscles of palate, pharynx, etc.; respiratory
organs; inhibitory to heart.
II. Spinal part.
Motor to Trapezius and Sternomastoid muscles
XII. i Hypoglossal. Motor to muscles of tongue.
THE FIRST OR OLFACTORY NERVE
1037
THE FIRST OR OLFACTORY NERVE (N. OLFACTORIUS).
The olfactory nerves or fila are the special nerves of the sense of smell, and are
about twenty in number on each side. These filaments constitute the first or
olfactory nerves and are the axones of the olfactory cells, lying in the small olfac-
tory region in the upper part of the superior concha and corresponding portion
of the septum and are macroscopically differentiated from the respiratory region
in being of a more brownish hue (Fig. 680). The olfactory fila are amyelinic and
FIG. 680. — Extent of true olfactory mucous membrane, (v. Brunn.)
exhibit a plexiform arrangement in the deeper layers. After piercing the cribrosa
(cribriform plate) of the ethmoid they become attached to the under surface of the
olfactory bulb, an oval mass of a grayish color, which rests on the cribriform
plate of the ethmoid bone and forms the anterior expanded extremity or a slender
process of brain-substance, named the olfactory tract. The olfactory tract and
bulb have already been described (p. 935). The olfactory tubercle (trigonum
olf actor ium) is a small triangular mass of gray substance between the diverging
roots of the optic tract (p. 935).
Each nerve is surrounded by tubular prolongations from the dura and pia,
the former being lost on the periosteum lining the nose, the latter in the neuri-
lemma of the nerve. The nerves, as they enter the nares, are divisible into two
groups: an inner group, larger than those on the outer wall, spread out over the
upper third of the septum; and an outer set, which is distributed over the superior
turbinated bone, and the surface of the ethmoid in front of it. As the filaments
descend, they unite in a plexiform network, and are believed by most observers
to terminate by becoming continuous with the deep .extremities of the olfactory cells.
The olfactory nerves differ in structure from other nerves in being composed
exclusively of non-medullated (amyelinic fibres). They are deficient in the white
substance of Schwann, and consist of axones with a distinct nucleated sheath,
in which there are, however, fewer nuclei than in ordinary amyelinic fibres.
The central olfactory pathways are described on p. 964.
1038
THE NERVE SYSTEM
Surgical Anatomy. — Destruction of the olfactory tract of one side causes loss of smell (anos-
mia) on the side of the injury, because the olfactory tract is practically uncrossed. In severe
injuries to the head the olfactory bulb may become separated from the olfactory nerves, thus
producing loss of the sense of smell, and with this a considerable loss in the sense.of taste, as much
of the perfection of the sense of taste is due to the sapid substances, being also odorous and
simultaneously exciting the sense of smell. When the sense of smell is lost, an individual cannot
distinguish the flavor of food, but he can distinguish that a substance is salt, or sweet, or bitter,
or acid. The most usual cause of injury to the olfactory nerve is fracture of the base of the skull
the line of fracture passing through the cribriform plate of the ethmoid bone, but a blow upon the
face, forehead, or back of the head, which does not produce fracture may injure the nerve.
THE SECOND OR OPTIC NERVE (N. OPTICUS).
The fibres of the optic nerve, the special nerve of the sense of sight, are the central
processes of the retinal ganglion cells which, after converging to the optic papilla,
leave the eyeball by piercing its fibrous and vascular tunics as a rounded cord.
The point of emergence is situated a little mesad (3 to 4 mm.) of the central axis of
the globe. Behind the eyeball the nerve passes backward and inward through
the orbital fat and optic foramen to enter the middle fossa of the cranium. The
total length of the nerve averages 45 to 50 mm. The two nerves converge to
decussate partially, forming the chiasm.
The Chiasm (chiasma opticum) (Figs. 681 and 682 and p. 919). — The chiasm
is somewhat quadrilateral in form, rests upon the olivary eminence and on the
anterior part of the diaphragma sellse, being bounded above by the terma; behind
by the tuber; on either side by the preperforatum. Within the commissure, the
optic nerves of the two sides undergo a partial decussation (Figs. 594 and 682)
described in detail on pp. 918 and 919.
FIG. 681.— The left optic nerve and optic tracts.
From half-retina
of same side.
Of opposite
side.
FIG. 682. — Course of the fibres in the optic commissure.
From the chiasm the optic tracts wind as
flattened bands obliquely caudo-laterad
around the crura to subdivide, each into
two bands, one (mesial root) passing to the
postgeniculum and not a true continuation
of the optic path (see Gudden's commissure,
p. 919), the other (lateral root) passing to
the pregeniculum, the pulvinar, and the
pregeminum (p. 919).
The optic path has been described on p.
917.
Surgical Anatomy.— The optic nerve is peculiarly liable- to become the seat of neuritis or
undergo atrophy in affections of the central nerve system, and, as a rule, the pathologic
relationship between the two affections is exceedingly difficult to trace. There are, however,
certain points in connection with the anatomy of this nerve which tend to throw light upon the
frequent association of these affections with intracranial disease: (1) From its mode of develop-
ment and from its structure the optic nerve must be regarded as a prolongation of the brain-
substance, rather than as an ordinary eerebro-spinal nerve. (2) As it passes from the brain it
receives sheaths from the three cerebral membranes — a perineural sheath from the pia, an
intermediate sheath from the arachnoid, and an outer sheath from the dura, which is also
connected with the periosteum as it passes through the optic foramen. These sheaths are
1039
separated from each other by spaces which communicate with the subdural and subarachnoid
spiico respectively. The innermost or perineural sheath sends a process around the arteria cen-
tralis retinre into the interior of the nerve, and enters intimately into its structure. Thus inflam-
matory infections of the meninges or of the brain may readily extend themselves along these
spaces or along the interstitial connective tissue in the nerve.
The course of the fibres in the optic commissure has an important pathologic bearing, and
his been the subject of much controversy. Microscopic examination, experiments, and pathology
all seem to point to the fact that there is a partial decussation of the fibres, each tract supplying
the corresponding half of each eye, so that the right tract supplies the right half of each eye, and
the left tract the left half of each eye. At the same time, Charcot believes — and his view has
met with general acceptation — that the fibres which do not decussate at the optic commissure
will decussate in the corpora quadrigemina, so that lesion of the cerebral centre of one side
causes complete blindness of the opposite eye, because both sets of decussating fibres are de-
stroyed. Whereas should one tract — say the right — be destroyed by disease, there will be
blindness of the right half of both retinae.
A .sagittal section through the commissure would divide the decussating fibres, and would
therefore produce blindness of the inner half of each eye; while a section at the margin of the
side of the optic commissure would produce blindness of the external half of the retina of the
same side.
The optic nerve may also be affected in injuries or diseases involving the orbit, in fractures
of the anterior fossa of the base of the skull, in tumors of the orbit itself, or those invading this
cavity from neighboring parts.
THE THIRD OR OCULOMOTOR NERVE (N. OCULOMOTORIUS)
(Figs. 683, 684, 687).
The third or oculomotor nerve supplies all the muscles of the orbit except the
Superior oblique and External rectus; it also supplies, through its connection
with the ciliary ganglion, the Sphincter muscle of the iris and the Ciliary muscle.
It is rather a large nerve, of rounded form and firm texture.
Its apparent origin is from the oculomotor groove along the ventro-mesal bor-
der of the crus. The deep origin may be traced through the substantia nigra and
tegmentum of the crus to a nucleus situated on either side of the median line beneath
the floor of the aqueduct. The nucleus of the oculomotor nerve also receives
fibres from the abducent nerve of the opposite side. The nucleus of the oculo-
motor nerve, considered from a physiological standpoint, can be subdivided into
several smaller groups of cells, each group controlling a particular muscle (see p.
911). The nerves to the different muscles appear to take their origin from before
backward, as follows: Inferior oblique, Inferior rectus, Superior rectus and
Levator palpebrse, Internal rectus; while from the cephalic end of the nucleus
the fibres for accommodation and for the Sphincter pupillse take their origin.
On emerging from the brain, the nerve is invested with a sheath of pia, and
enclosed in a prolongation from the arachnoid. It passes between precerebellar
and postcerebral arteries, and then pierces the dura in front of and external to
the posterior clinoid process, passing between the two processes from the free and
attached borders of the tentorium, which are prolonged forward to be connected
with the anterior and posterior clinoid processes of the sphenoid bone. It passes
along the outer wall of the cavernous sinus (Figs. 454 and 455) ; above the other
orbital nerves, receiving in its course one or two filaments from the cavernous
plexus of the sympathetic, and a communicating branch from the first division
of the trigeminal nerve. It then divides into two branches, which enter the orbit
through the sphenoidal fissure, between the two heads of the External rectus
muscle (Fig. 683). On passing through the fissure, the nerve is placed below
the trochlear nerve and the frontal and lacrimal branches of the ophthalmic nerve,
and has passing between its two divisions the nasal nerve (Fig. 692).
The Superior Division (ramus superior] (Fig. 684). — The superior division, the
smaller, passes inward over the optic nerve, and supplies the Superior rectus and
Levator palpebras.
1040
THE NER VE SYSTEM
Infratrochlear
nerve.
The Inferior Division (ramus inferior) (Fig. 684).— The inferior division, the
larger, divides into three branches. One passes beneath the optic nerve to the •
Internal rectus; another, to the Inferior rectus; and the third, the longest of the
three, passes forward between the
Inferior and External recti to the
Inferior oblique. From this latter
a short, thick branch, radix brevis
ganglii ciliaris, is given off to the lower
part of the ciliary or lenticular ganglion
and forms its short or motor root
(Figs. 684 and 687). It also gives off
one or two filaments to the Inferior
rectus. All these branches enter the
muscles on their ocular surface, ex-
cept that to the Inferior oblique,
which enters its posterior border.
Surgical Anatomy.— Paralysis of the
oculomotor nerve may be the result of
many causes: as cerebral disease; condi-
tions causing pressure on the cavernous
sinus; periostitis of the bone entering into
the formation of the sphenoidal fissure;
fracture of the orbit. It results, when com-
plete, in (1) ptosis, or drooping of the upper
eyelid, in consequence of the Levator pal-
pebrse being paralyzed; (2) external stra-
bismus, on account of the unopposed action
of the External rectus muscle, which is not
supplied by the oculomotor nerve, and is
not therefore paralyzed; (3) dilatation of
the pupil, because the sphincter fibres of
the iris are paralyzed ; (4) loss of power of
accommodation, as the Sphincter pupillee,
Motor root. / ^—Recurrent filament the Ciliary muscle, and the Internal rectus
Sensor root. are paralyzed; (5) slight prominence of
FIG. 683,-Nerves of the orbit, seen from above. tjje eyeball, owing to most of its muscles
being relaxed. Occasionally paralysis may
affect only a part of the nerve; that is to say, there may be, for example, a dilated and fixed
pupil, with ptosis, but no other signs. Irritation of the nerve causes spasm of one or other of
^Oculomoter 'Nerve
From Cavernous Plexus
__ OWiguus
Inferior
FIG. 684. — Plan of the oculomotor nerve.
the muscles supplied by it; thus, there may be internal strabismus from spasm of the Internal
rectus; accommodation for near objects only from spasm of the Ciliary muscle, or contraction
of the pupil (myosis), from irritation of the sphincter of the pupil.
THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE 1Q41
THE FOURTH OR TROCHLEAR NERVE (N. TROCHLEARIS) (Figs. 683 and 687).
The fourth or trochlear nerve or patheticus, with the exception of the n. inter-
medius, the smallest of the cranial nerves, supplies the Superior oblique muscle.
The apparent origin, at the base of the brain, is on the outer side of the crus
cerebri, just in front of the pons, but the fibres can be traced backward behind
the quadrigemina to the valvula, on the upper surface of which the two nerves
decussate, decussatio nervorum trochlearium. Its deep origin may be traced to a
nucleus in the floor of the aqueduct immediately below that of the oculomotor
nerve, with which it is continuous (Fig. 578).
Emerging from the valvula, the nerve is directed outward across the prepe-
(1 uncle of the cerebellum, and then winds forward around the outer side of the
cms cerebri, immediately above the pons, pierces the dura in the free border of the
tentorium, just behind, and external to, the posterior clinoid process, and passes
forward in the outer wall of the cavernous sinus, between the oculomotor nerve
and the ophthalmic division of the trigeminal nerve (Figs. 454 and 455). It crosses
the oculomotor nerve and enters the orbit through the sphenoidal fissure (Fig.
692). It now becomes the highest of all the nerves, lying at the inner extremity
of the fissure internal to the frontal nerve. In the orbit it passes inward, above
the origin of the Levator palpebrse, and finally enters the orbital surface of the
Superior oblique muscle. In the outer wall of the cavernous sinus this nerve is
not infrequently blended with the ophthalmic division of the trigeminal nerve.
Branches of Communication. — In the outer wall of the cavernous sinus it
receives some filaments from the cavernous plexus of the sympathetic. In the
sphenoidal fissure it occasionally gives off a branch to assist in the formation of
the lacrimal nerve.
Branches of Distribution. — It gives off a recurrent branch, which passes
backward between the layers of the tentorium, dividing into two or three filaments
which may be traced as far back as the wall of the lateral sinus.
Surgical Anatomy. — The trochlear nerve when paralyzed causes loss of function in the Superior
oblique, so that the patient is unable to turn his eye downward and outward. Should the patient
attempt to do this, the eye on the affected side is twisted inward, producing diplopia or double
vision. Accordingly, it is said that the first symptom of this disease which presents itself is giddi-
ness when going down hill or in descending stairs, owing to the double vision induced by the
patient looking at his steps while descending.
THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE (N. TRIGE MINUS)
Figs. 683, 685, 686, 687, 688, 689, 690, 691).
The fifth or trigeminal or trifacial nerve is the largest cranial nerve. It resembles
a spinal nerve (1) in having two roots; (2) in having a ganglion developed on
its dorsal root; and (3) in its function, since it is a compound nerve. It is the
great sensor nerve of the head and face and the motor nerve of the muscles
of mastication. Its upper two divisions, portio major, are entirely sensor, the
third division, portio minor, is partly sensor and partly motor. It arises by two
roots : of these the ventral is the smaller, and is the motor root (Fig. 578) ; the
dorsal, the larger and sensor root. Its superficial origin is from the side of
the pons nearer to the upper than the lower border (Fig. 578). The smaller
root consists of three or four bundles ; the larger root consists of numerous bundles
of fibres, varying in number from seventy to a hundred. The two roots are
separated from one another by a few of the transverse fibres of the pons. The
66
1042 THE NERVE SYSTEM
deep termination of the larger or sensor root is chiefly in a long tract in the
oblongata, the lower sensor nucleus, which is continuous below with the gliosa
or substantia gelatinosa of Rolando. The fibres from this nucleus form the
so-called ascending root of the fifth nerve ; they pass upward through the pons
and join with fibres from the locus coeruleus or upper sensor nucleus (Fig. 578),
which is situated to the outer side of the nucleus, from which the lower part of the
motor root takes origin. The deep origin of the smaller or motor root is derived
partly from a nucleus embedded in the gray substance of the upper part of the floor
of the fourth ventricle and partly from a collection of nerve-cells situated at the
side of the aqueduct from which the fibres pass caudad under the name of the
descending root of the fifth nerve (Fig. 578).
The two roots of the nerve pass forward below the tentorium as it bridges over
the notch on the inner part of the superior border of the petrous portion of the
temporal bone (Fig. 686); they then run between the bone and the dura to the
apex of the petrous portion of the temporal bone, where the fibres of the sensor
root appear to enter into the formation of the large semilunar or Gasserian ganglion
(Figs. 685 and 686), while the motor root passes beneath the ganglion without
having any connection with it, and joins outside the cranium with one of the trunks
derived from it (Figs. 685 and 686).
OCULOMOTOR TROCHLEAR ABOUCENS
NERVE NERVE NERVE
MOTOR PORTION
OF FIFTH NERVE
SENSOR PORTION
OFTRIGEMINAL NERVE
SEMILUNAR NERVE
(Gasserian ganglion)
MAXILLARY
NERVE
MANDIBULAR
NERVE
FIQ. 685. — The right semilunar or Gasserian ganglion, viewed from the medial side. (Spalteholz.)
The Gasserian or Semilunar Ganglion1 (ganglion semilunare) (Figs. 685, 686,
687, 688, 689, and 690). — The Gasserian or semilunar ganglion is lodged in an
osteo-fibrous space, the cavum Meckelii (Figs. 644 and 686), near the apex of the
petrous portion of the temporal bone. The ganglion is of somewhat crescentic
form, with its convexity turned forward. Its upper surface is intimately adherent
to the dura. Besides the small or motor root, the large superficial petrosal nerve
lies underneath the ganglion.
Branches of Communication. — This ganglion receives on its inner side filaments
from the carotid plexus of the sympathetic.
Branches of Distribution. — It gives off minute branches to the tentorium and the
dura in the middle fossa of the cranium. From its anterior border, which is
1 A Viennese anatomist, Raimund Balthasar Hirsch (1765), was the first who recognized the ganglionic
nature of the swelling on the sensory root of the fifth nerve, and called it, in honor of his otherwise unknown
teucher, Jon. Laur. Gasser, the " Ganglion Gasseri." Julius Casserius, whose name is given to the musculo-
cutaneous nerve of the arm, was professor at Padua, 1545-1605. (See Hyrtl, Lehrbuch der Anatomic, p. 895
and p. 55.) — ED. of 15th English edition.
THE FIFTH, TRIGEM I .\.\L OR TRIFACIAL NERVE
1043
directed forward and outward, three large branches proceed — the ophthalmic,
superior maxillary, and inferior maxillary. The ophthalmic and superior maxillary
consist exclusively of fibres derived from the larger root and ganglion, and are solely
nerves of common sensation. The third division, or inferior maxillary, is joined
outside the cranium by the motor root. This, therefore, strictly speaking, is the
only portion of the trigeminal nerve which can be said to resemble a spinal nerve.
Ophthalmic Nerve (»i. ophthalmicus) (Figs. 683, 685, 686, 687, 688, 689, and
690). — The ophthalmic or first division of the trigeminal is a sensor nerve. It
supplies the eyeball, the lacrimal
gland, the mucous lining of the eye
and nasal fossa?, and the integument
of the eyebrow, forehead, and nose
(Fig. 691). It is the smallest of the
three divisions of the fifth, arising from
the upper part of the Gasserian gan-
glion. It is a short, flattened band,
about 2 cm. in length, which passes
forward along the outer wall of the
cavernous sinus (Figs. 454 and 455),
below the other nerves (Fig. 685), and
just before entering the orbit, through
the sphenoidal fissure, divides into
three branches — lacrimal, frontal, and
nasal (Figs. 683, 687, and 688).
Branches of Communication. — The
ophthalmic nerve gives off in the
cavernous sinus a branch to the dura
(ji. tentorii), is joined by filaments
from the cavernous plexus of the sym-
pathetic, and gives off minute branches to communicate with the oculomotor and
abducent nerves, and not infrequently with the trochlear.
Branches of Distribution. — It gives off recurrent filaments which pass between
the layers of the tentorium, and then divide into —
Lacrimal. Frontal. Nasal.
The Lacrimal Nerve (n. lacrimalis) (Figs. 683, 687, and 688). — The lacrimal
is the smallest of the three branches of the ophthalmic. It sometimes receives
a filament from the trochlear nerve, but this is possibly derived from the branch
of communication which passes from the ophthalmic to the trochlear. It passes
forward in a separate tube of dura, and enters the orbit through the nar-
rowest part of the sphenoidal fissure (Fig. 692). In the orbit it runs along the
upper border of the External rectus muscle, with the lacrimal artery, and com-
municates with the temporomalar branch of the superior maxillary nerve. It
enters the lacrimal gland and gives off several filaments, which supply the
gland and the conjunctiva. Finally, it pierces the superior palpebral ligament,
and terminates in the integument of the upper eyelid, joining with filaments of
the facial nerve. The lacrimal nerve is occasionally absent, when its place is
taken by the temporal branch of the superior maxillary. Sometimes the latter
branch is absent, and a continuation of the lacrimal is substituted for it.
The Frontal Nerve (n. frontalis) (Figs. 683 and 687). — The frontal is the largest
division of the ophthalmic, and may be regarded, both from its size and direc-
tion, as the continuation of the nerve. It enters the orbit above the muscles,
through the sphenoidal fissure (Fig. 692), and runs forward along the middle line,
between the Levator palpebrae and the periosteum. Midway between the apex and
the base of the orbit it divides into two branches, supratrochlear and supraorbital.
SENSOR ROOT.
DIVIDED
SUPERIOR
PETROSAL SINUS
FACIAL AND
ACOUSTIC NERVES
FIG. 686. — The course of the motor root of the trigem-
inal nerve. (Poirier and Charpy.)
1044
THE NERVE SYSTEM
The Supratrochlear Branch (n. supratrochlearis) (Fig. 683), the smaller of the
two, passes inward, above the pulley of the superior oblique muscle, and gives
off a descending filament, which joins with the infratrochlear branch of the nasal
nerve. It then escapes from the orbit between the pulley of the Superior oblique and
the supraorbital foramen, curves up on to the forehead close to the bone, ascends
beneath the Corrugator supercilii and Occipito-frontalis muscles, and, dividing
into branches which pierce these muscles, it supplies the integument of the lower
part of the forehead on either side of the middle line and sends filaments to the
conjunctiva and skin of the upper lid.
The Supraorbital Branch (n. supraorbitalis] (Fig. 692) passes forward through
the supraorbital foramen, and gives off, in this situation, palpebral filaments to
the upper eyelid. It then ascends upon the forehead, and terminates in cutaneous
and pericranial branches.
The cutaneous branches, two in number, an inner and an outer, supply the integ-
ument of the cranium as far back as the vertex. They are at first situated beneath
the Occipito-frontalis, the inner branch perforating the frontal portion of the
muscle, the outer branch its tendinous aponeurosis.
The pericranial branches are distributed to the pericranium over the frontal and
parietal bones.
Internal carotid artery
and carotid plexus.
FIG. 687. — Nerves of the orbit and ophthalmic ganglion, side view.
The Nasal Nerve (n. nasociliaris) (Figs. 683 and 687). — The nasal nerve is
intermediate in size between the frontal and lacrimal, and more deeply placed
than the other branches of the ophthalmic. It enters the orbit by way of the
sphenoidal fissure (Fig. 692) between the two heads of the External rectus,
and passes obliquely inward across the optic nerve, beneath the Superior rectus
and Superior oblique muscles, to the inner wall of the orbit, where it passes through
the anterior ethmoidal foramen, and, entering the cavity of the cranium, tra-
verses a shallow groove on the front of the cribriform plate of the ethmoid
bone, and passes down, through the slit by the side of the crista galli, into the
nose (Fig. 689), where it divides into two branches, an internal and an external
branch. The internal branch (rami nasales mediales) supplies the mucous mem-
brane near the forepart of the septum of the nose. The external branch (rami
nasales laterales] descends in a groove on the inner surface of the nasal bone, and
supplies a few filaments to the mucous membrane covering the forepart of the
outer wall of the nares as far as the inferior turbinate bone; it then leaves the cavity
THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE 1045
of the nose, between the lower border of the nasal bone and the upper lateral
cartilage of the nose, and, passing down beneath the Compressor nasi, supplies
the integument of the ala and the tip of the nose, joining with the facial nerve.
Branches. — The branches of the nasal nerve are the ganglionic, ciliary, and infra-
trochlear.
The Ganglionic Branch or the long root of the ciliary ganglion (radix longa ganglii
cilia rix) (Figs. 684 and 687) is a slender branch, about 1 to 2 cm. in length,
which usually arises from the nasal nerve, between the two heads of the External
rectus muscle. It passes forward on the outer side of the optic nerve, and enters
the postero-superior angle of the ciliary ganglion, forming its long root. It is
sometimes joined by a filament from the cavernous plexus of the sympathetic or
from the superior division of the third nerve.
The Long Ciliary Nerves (/m. ciliares longi), two or three in number, are given
off from the nasal as it crosses the optic nerve. They join the short ciliary nerves
(Figs. 684 and 687) from the ciliary ganglion, pierce the posterior part of the sclera,
and, running forward between it and the choroid, are distributed to the ciliary
muscle, iris, and cornea.
The Infratrochlear Branch (n. infratrochlearis) (Fig. 683) is given off just before
the nasal nerve passes through the anterior ethmoidal foramen. It runs for-
ward along the upper border of the Internal rectus muscle, and is joined, beneath
the pulley of the Superior oblique, by a filament from the supratrochlear nerve.
It then passes to the inner angle of the eye, and supplies the integument of the
evelids and side of the nose, the conjunctiva, the lacrimal sac, and the caruncula
lacrimalis.
Connected with the three divisions of the trigeminal nerve are four small ganglia.
With the first division is connected the ophthalmic ganglion; with the second
division, the sphenopalatine or Meckel's ganglion ; and with the third, the otic and
submaxillary ganglia. All the four receive sensor filaments from the trigeminal
nerve, and motor and sympathetic filaments from various sources; these filaments
are called the roots of the ganglia.
The Ophthalmic, Lenticular or Ciliary Ganglion (ganglion ciliare) (Figs. 684 and
687) is a small, quadrangular, flattened ganglion, of a reddish-gray color, and
about the size of a pin's head, situated at the back part of the orbit between the
optic nerve and the External rectus muscle, lying generally on the outer side of
the ophthalmic artery. It is enclosed in a quantity of loose fat, which makes its
exposure by dissection somewhat difficult.
Its branches of communication or roots are three, all of which enter its posterior
border. One, the long or sensor root (radix longa ganglii ciliaris], is derived
from the nasal branch of the ophthalmic and joins the superior angle of the
ganglion. The second, the short or motor root (radix brevis ganglii ciliaris), is a
short, thick nerve, occasionally divided into two parts, which is derived from the
branch of the oculomotor to the Inferior oblique muscle, and is connected with
the inferior angle of the ganglion. The third, the sympathetic root (radix sympa-
thetica ganglii ciliaris), is a slender filament from the cavernous plexus of the
sympathetic. This is frequently blended with the long root, although it some-
times passes to the ganglion separately. The ganglion occasionally receives a
filament of communication from the sphenopalatine ganglion.
Its branches of distribution are the short ciliary nerves (nn. ciliares breves] (Figs.
684 and 687). These are delicate filaments, from six to ten in number, which
arise from the forepart of the ganglion in two bundles, connected with its superior
and inferior angles; the lower bundle is the larger. They run forward with the
ciliary arteries in a wavy course, one set above and the other below the optic
nerve, and are accompanied by the long ciliary branches of the nasal nerve.
They pierce the sclera at the back part of the globe, pass forward in delicate
1046 THE NERVE SYSTEM
grooves on its inner surface, and are distributed to the Ciliary muscle, iris, and
cornea. One small branch is said to penetrate the optic nerve with the arteria
centralis retinte.
The circular fibres of the iris are innervated by the oculomotor nerve; the
radiating fibres are innervated by the sympathetic.
The Superior Maxillary Nerve (n. maxillaris) (Figs. 685, 686, 687, and 688).
—The superior maxillary or second division of the trigeminal is a sensor nerve.
It is intermediate, both in position and size, between the ophthalmic and inferior
maxillary. It commences at the middle of the Gasserian ganglion as a flat-
tened plexiform band (Fig. 685), and, passing horizontally forward, it leaves the
skull through the foramen rotundum (Fig. 686), where it becomes more cylindrical
in form and firmer in texture. It then crosses the spheno-maxillary fossa (Fig. 67)
enters the orbit through the spheno-maxillary fissure, traverses the infraorbital
canal in the floor of the orbit, and appears upon the face at the infraorbital fora-
men. After it enters the infraorbital canal the nerve is usually called the infra-
orbital (n. infraorbitalis), and is, therefore, the terminal branch of the superior
maxillary nerve (Fig. G88). At its termination the nerve lies beneath the Levator
labii superioris muscle, and divides into a leash of branches, which spread out
upon the side of the nose, the lower eyelid, and upper lip, joining with filaments
of the facial nerve.
Branches of Distribution. — The branches of this nerve may be divided into four
groups: 1. Those given off in the cranium. 2. Those given off in the spheno-
maxillary fossa. 3. Those in the infraorbital canal. 4. Those on the face.
In the cranium . . . Dural.
( Orbital or temporo-malar.
Spheno-maxillary fossa . < Spheno-palatine.
( Posterior superior dental.
Infraorbital canal f Middle superior dental.
J-IJIlttUl Ulldl ( <l 1 1<1 1 . . . ^i A • • i j. i
[ Anterior superior dental.
( Palpebral.
On the face . < Nasal.
t Labial.
The Dural Branch (n. meningeus medius). — The dural branch is given off by
the superior maxillary nerve directly after its orgin from the Gasserian ganglion;
it accompanies the medidural artery and supplies the dura of the middle fossa
of the base of the skull.
The Orbital or Temporo-malar Branch (n. zygomaticus] (Figs. 687 and 688).—
The orbital or temporo-malar branch arises in the spheno-maxillary fossa, enters
the orbit by the spheno-maxillary fissure, and divides at the back of that cavity
into two branches, temporal and malar.
The Temporal Branch (ramus zygomaticotemporalis) runs in a groove along the
outer wall of the orbit (in the malar bone,), receives a branch of communication
from the lacrimal, and, passing through a foramen in the malar bone, enters the
temporal fossa. It ascends between the bone and the substance of the Temporal
muscle, pierces this muscle and the temporal fascia about an inch above the
zygoma, and is distributed to the integument covering the temple and side of
the forehead, communicating with the facial and the auriculo-temporal branch of
the inferior maxillary nerve. As it pierces the temporal fascia it gives off a slender
twig, which runs between the two layers of the fascia to the outer angle of the
orbit.
The Malar Branch (ramus zygomaticofacialis) passes along the external inferior
angle of the orbit, emerges upon the face through a foramen in the malar bone,
and, perforating the Orbicularis palpebrarum muscle, supplies the skin on the
THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE 1047
prominence of the cheek, where it is named the subcutaneus malae. It joins with
the facial and the palpebral branches of the superior maxillary.
The Spheno-palatine Branches (nn. sphenopalatini) (Fig. 688).— The spheno-
palutine branches, two in number, descend to the spheno-palatine ganglion, of
which ganglion they are the sensor or short roots.
The Posterior Superior Dental Branches (rami alveolares superiores posteriores]
(Fig. 688). — The posterior superior dental branches arise from the trunk of the
nerve just as it is about to enter the infraorbital canal; they are generally two
in number, but sometimes arise by a single trunk, and immediately divide and
pass downward on the tuberosity of the superior maxillary bone. They give
off several twigs to the gums and neighboring parts of the mucous membrane of
the cheek, superior gingival branches (rami gingivales superiores}. They then
enter the posterior dental canals on the zygomatic surface of the superior maxil-
Auriculo-temporal/
nerve.
FIG. 688. — Distribution of the second and third divisions of the fifth nerve and submaxillayy ganglion.
lary bone, and, passing from behind forward in the substance of the bone, com-
municate with the middle dental nerve by a plexus formation, and give off branches
to the lining membrane of the antrum and three twigs to each of the molar teeth.
These twigs enter the foramina at the apices of the fangs and supply the pulp.
The Middle Superior Dental Branch (ramus alveolaris superior medius}. — The
middle superior dental branch is given off from the superior maxillary nerve in the
back part of the infraorbital canal, and runs downward and forward in a special
canal in the outer wall of the antrum to supply the two bicuspid teeth. It com-
municates with the posterior and anterior dental branches by a plexus formation.
At its point of communication with the posterior branch, above the root of the
second bicuspid tooth, is a slight thickening which is the so-called ganglion of
Valentin; and at its point of communication with the anterior branch is a second
1048 THE NER VE SYSTEM
enlargement, which is called the ganglion of Bochdalek. Neither of these is a true
ganglion.
The Anterior Superior Dental Branch (ramus alveolaris superior anterior es}. — The
anterior superior dental branch, of large size, is given off from the superior maxil-
lary nerve just before its exit from the infraorbital foramen; it enters a special
canal in the anterior wall of the antrum, and divides into a series of branches
which supply the incisor and canine teeth. It communicates with the middle
dental nerve by a plexus, and gives off a nasal branch, which passes through a
minute canal into the nasal fossa, and supplies the mucous membrane of the
forepart of the inferior meatus and the floor of the cavity, communicating with
the nasal branches from the spheno-palatine ganglion.
The superior dental plexus (plexus dentalis superior) is formed by twigs of the
three superior dental nerves. From the plexus come the nerves which supply the
teeth of the upper jaw (rami dentales superior es} and the gums (rami gingivales
super lores}.
The branches upon the face are known as the rami n. infraorbitalis (Fig. 688).
There are three sets of them.
The Palpebral Branches (rami palpebrales inferiores). — The palpebral branches
pass upward beneath the Orbicularis palpebrarum muscle. They supply the
integument and conjunctiva of the lower eyelid with sensation, joining at
the outer angle of the orbit with the facial nerve and the malar branch of the
orbital.
The Nasal Branches (rami nasales interni}. — The nasal branches pass inward:
they supply the integument of the side of the nose and join with the nasal branch
of the ophthalmic.
The Labial Branches (rami labiales superior es]. — The labial branches, the
largest and most numerous, descend beneath the Levator labii superioris muscle,
and are distributed to the integument of the upper lip, the mucous membrane
of the mouth, and the labial glands.
All these branches are joined, immediately beneath the orbit, by filaments from
the facial nerve, forming an intricate plexus, the infraorbital plexus.
The Spheno-palatine or Meckel's Ganglion (ganglion sphenopalatinum} (Fig.
689). — The spheno-palatine ganglion, the largest of the cranial ganglia, is deeply
placed in the spheno-maxillary fossa, close to the spheno-palatine foramen. It
is triangular or heart-shaped, of a reddish-gray color, and is situated just below
the superior maxillary nerve as it crosses the fossa.
Branches of Communication. — Like the other ganglia of the trigeminal nerve, it
possesses a motor, a sensor, and a sympathetic root. Its sensor root is derived
from the superior maxillary nerve through its two spheno-palatine branches
(p. 1047). These branches of the nerve are given off in the spheno-maxillary fossa
and descend to the ganglion. Their fibres, for the most part, pass in front of the
ganglion, as they proceed to their destination, in the palate and nasal fossa, and
are not incorporated in the ganglionic mass; some few of the fibres, however, enter
the ganglion, constituting its sensor root. Its motor root is derived from the facial
nerve through the large superficial petrosal nerve, and its sympathetic root from
the carotid plexus, through the large deep petrosal nerve. These two nerves join
together before their entrance into the ganglion to form a single nerve, the Vidian.
The Large or Great Superficial Petrosal Branch (n. petrosus super ficialis major}
(Fig. 693) is given off from the geniculate ganglion of the facial nerve in the
aquaeductus Fallopii; it passes through the hiatus Fallopii; enterS the cranial
cavity, and runs forward, being contained in a groove on the anterior surface
of the petrous portion of the temporal bone and lies beneath the dura. It then
enters the cartilaginous substance which fills in the foramen lacerum medium basis
cranii, and, joining with the large deep petrosal branch, forms the Vidian nerve.
THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE
1049
The Large or Great Deep Petrosal Branch (n. petrosus prof undies') (Fig. 694) is
given off from the carotid plexus of the sympathetic upon the internal carotid
artery, and runs through the carotid canal on the outer side of the internal carotid
artery. It then enters the cartilaginous substance which fills in the foramen
laecTiim medium basis cranii, and joins with the large superficial petrosal nerve
to form the Vidian.
The Vidian Nerve (n. canalis pterygoidei) (Fig. 689), formed in the cartilagi-
nous substance which fills in the middle lacerated foramen by the junction of
the two preceding nerves, passes forward, through the Vidian canal, with the
artery of the same name, and is joined by a small ascending nervous branch, the
sphenoidal branch, from the otic ganglion. Finally, it enters the spheno-maxillary
fossa, and joins the posterior angle of the spheno-palatine ganglion.
Branches of Distribution of the Spheno-palatine Ganglion. — Its branches of distri-
bution are divisible into four groups: ascending, which pass to the orbit; descend-
ing, to the palate; internal, to the nose; and posterior branches, to the pharynx and
nasal fossae.
Termination of
naso-palatine
nerve.
FIG. 689. — The spheno-palatine or Meckel's ganglion and its branches.
The Ascending Branches (rami orbitales} are two or three delicate filaments which
enter the orbit by the spheno-maxillary fissure, and supply the periosteum. Accord-
ing to Luschka, some filaments pass through foramina in the suture between the
os planum of the ethmoid and frontal bones to supply the mucous membrane of
the posterior ethmoidal and sphenoidal sinuses.
The Descending or Palatine Branches (nn. palatini) (Fig. 689) are distributed
to the roof of the mouth, the soft palate, tonsil, and lining membrane of the nose.
They are almost a direct continuation of the spheno-palatine branches of the
superior maxillary nerve, and are three in number — anterior, middle, and posterior.
The anterior or large palatine nerve (n. palatinus anterior} descends through
the large posterior palatine canal, emerges upon the hard palate at the posterior
palatine foramen, and passes forward through a groove in the hard palate nearly
1050 THE NER VE SYSTEM
as far as the incisor teeth. It supplies the gums, the mucous membrane and glands
of the hard palate, and communicates in front with the termination of the naso-
palatine nerve (see below). While in the posterior palatine canal it gives oft' inferior
nasal branches (rami nasales posteriores inferiores), which enter the nose through
openings in the palate bone, and ramify over the inferior turbinated bone, the
middle and the inferior meatus; and at its exit from the canal a palatine branch
is distributed to both surfaces of the soft palate.
The middle or external palatine nerve (n. palatinus medius) descends through
one of the accessory palatine canals, distributing branches to the uvula, tonsil,
and soft palate. It is occasionally wanting.
The posterior or small palatine nerve (n. palatinus posterior} descends with a
minute artery through the small posterior palatine canal, emerging by a separate
opening behind the posterior palatine foramen. It supplies the Levator palati
and Azygos uvulae muscles,1 the soft palate, tonsil, and uvula. The middle and
posterior palatine join with the tonsillar branches of the glosso-pharyngeal to form
the plexus around the tonsil, the circulus tonsillaris.
The Internal Branches are distributed to the septum and outer wall of the nasal
fossae. They are the posterior superior nasal and the naso-palatine.
The posterior superior nasal branches (rami nasales posteriores superiores), three
in number, enter the back part of the nasal fossa by the spheno-palatine foramen.
They supply the mucous membrane covering the superior and middle spongy
bones, and that lining the posterior ethmoidal cells, a few being prolonged to the
upper and back part of the septum.
The naso-palatine nerve (n. nasopalatinus} has been called the nerve of Scarpa
and also the nerve of Cotunnius. It enters the nasal fossa through the spheno-
palatine foramen, and passes inward across the roof of the nose, below the orifice
of the sphenoidal sinus, to reach the septum; it then runs obliquely downward and
forward along the lower part of the septum, to the anterior palatine foramen,
lying between the periosteum and mucous membrane. It descends to the roof of
the mouth through the anterior palatine canal (Fig. 689). The two nerves are here
contained in separate and distinct canals, situated in the intermaxillary suture, and
termed the foramina of Scarpa, the left nerve being usually anterior to the right
one. In the mouth they become united, supply the mucous membrane behind
the incisor teeth, and join with the anterior palatine nerve. The naso-palatine
nerve furnishes a few small filaments to the mucous membrane of the septum.
The Posterior Branches are the pharyngeal or pterygo-palatine and the upper
posterior nasal branches.
The pharyngeal or pterygo-palatine nerve (Fig. 689) is a small branch arising
from the back part of the spheno-palatine ganglion, being generally blended with
the Vidian nerve. It passes through the pterygo-palatine canal with the pterygo-
palatine artery, and is distributed to the mucous membrane of the upper part
of the pharynx, behind the Eustachian tube.
The upper posterior nasal branches are a few twigs given off from the posterior
part of the spheno-palatine ganglion, which run backward in the sheath of the
Vidian nerve to the mucous membrane at the back part of the roof, septum, and
superior meatus of the nose and that covering the end of the Eustachian tube.
The Mandibular or Inferior Maxillary Nerve (n. mandibularis) (Figs. 685,
687, and 688). — The inferior maxillary or third division of the trigeminal nerve dis-
tributes branches to the teeth and gums of the lower jaw, the integument of the
temple and external ear, the lower part of the face and lower lip, and the muscles
of mastication ; it also supplies the tongue with a large branch. It is the largest of
the three divisions of the trigeminal, and is made up of two roots: a large or sensor
1 It is probable that this is not the true motor supply to these muscles, but that they are supplied by the
accessory nerve through the pharyngeal plexus. — ED. of 15th English edition.
THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE 1051
root, proceeding from the inferior angle of the Gasserian ganglion; and a small or
motor root, which passes beneath the ganglion and unites with the sensor root just
after its exit from the skull through the foramen ovale (Figs. 685, 686, and 688).
Immediately beneath the base of the skull this nerve divides into two trunks,
anterior and posterior. Previous to its division the primary trunk gives off from
its inner side a recurrent branch and the nerve to the Internal pterygoid muscle.
The Recurrent or Meningeal Branch (n. spinosus). — The recurrent or meningeal
branch is given off directly after the exit of the mandibular nerve from the foramen
ovale. It passes backward into the skull through the foramen spinosum with
the medidural artery. It divides into two branches, anterior and posterior,
which accompany the main divisions of the artery and supply the dura. The pos-
terior branch also supplies the mucous lining of the mastoid cells. The anterior
branch communicates with the dural branch of the superior maxillary nerve.
The Internal Pterygoid Nerve (n. pterygoideus internus). — Tht internal ptery-
goid nerve, given off from the inferior maxillary previous to its division, is inti-
mately connected at its origin with the otic ganglion. It is a long and slender
branch, which passes inward to enter the deep surface of the Internal pterygoid
muscle.
The anterior and smaller division of the inferior maxillary nerve, which receives
nearly the whole of the motor root of the trigeminal nerve, divides into branches
which supply the muscles of mastication. They are the masseteric, deep temporal,
buccal, and external pterygoid branches (Fig. 688).
The Masseteric Branch (n. massetericus) passes outward, above the External
pterygoid muscle, in front of the temporo-mandibular articulation and behind the
tendon of the temporal muscle; it crosses the sigmoid notch with the masseteric
artery, to the deep surface of the Masseter muscle, in which it ramifies nearly as
far as its anterior border. It occasionally gives a branch to the Temporal muscle,
and a filament to the articulation of the jaw.
The Deep Temporal Branches (nn. temporales profundi), two in number, anterior
and posterior, supply the deep surface of the Temporal muscle. The posterior
branch (n. temporalis profundus posterior), of small size, is placed at the back of
the temporal fossa. It is sometimes joined with the masseteric branch. The
anterior branch (n. temporalis profundus anterior) is frequently given off from the
buccal nerve; it is reflected upward, at the pterygoid ridge of the sphenoid, to the
front of the temporal fossa. Sometimes there are three deep temporal branches,
and if this maintains the third branch, the middle deep temporal, passes outward
above the External pterygoid muscle, and runs upward on the bone to enter the
deep surface of the Temporal muscle.
The Buccal or Buccinator Branch (n. buccinatorius) passes forward between the
two heads of the External pterygoid, and downward beneath the inner surface of
the coronoid processes of the lower jaw, or through the fibres of the Temporal
muscle, to reach the surface of the Buccinator muscle, upon which it divides into
a superior and an inferior branch. It gives a branch to the External pterygoid
during its passage through that muscle, and a few ascending filaments to the
Temporal muscle, one of which occasionally joins with the anterior branch of the
deep temporal nerve. The superior or upper branch supplies the integument and
upper part of the Buccinator muscle, joining with the facial nerve around the
facial vein. The inferior or lower branch passes forward to the angle of the mouth;
it supplies the integument and Buccinator muscle, as well as the mucous membrane
lining the inner surface of that muscle, and joins the facial nerve.1
The External Pterygoid Nerve (n. pterygoideus externus) is most frequently
derived from the buccal, but it may be given off separately from the anterior
trunk of the mandibular nerve. It enters the muscle on its inner surface.
1 There seems to be no reason to doubt that the branch supplying the Buccinator muscle is entirely a nerve of
ordinary sensation, and that the true motor supply of this muscle is from the facial. — ED. of 15th English edition.
1052 THE NER VE SYSTEM
The posterior and larger division of the inferior maxillary nerve is for the most part
sensor, but receives a few filaments from the motor root. It divides into three
branches: auriculo-temporal, lingual (gustatory), and inferior dental (Fig. 688).
The Auriculo-temporal Nerve (n. auriculotemporalis) (Fig. 690) generally arises
by two roots, between which the medidural artery passes. It runs backward
beneath the External pterygoid muscle to the inner side of the neck of the lower
jaw. It then turns upward with the temporal artery, between the external ear
and the condyle of the jaw, under cover of the parotid gland, and, escaping from
beneath this structure, ascends over the zygoma and divides into two temporal
branches.
The branches of communication are with the facial and with the otic ganglion.
The branches of communication with the facial (rami anastomotici cum n. faciali],
usually two in number, pass forward from behind the neck of the condyle of the
jaw, to join this nerve at the posterior border of the Masseter muscle. They
form one of the principal branches of communication between the facial and the
trigeminal nerve. The filaments of communication with the otic ganglion are
derived from the commencement of the auriculotemporal nerve.
The branches of distribution are —
Anterior auricular. Articular.
Branches to the meatus auditorius. Parotid.
Superficial temporal.
The anterior auricular branches (nn. auriculares anteriores) are usually two in
number. They supply the front of the upper part of the pinna, being distributed
principally to the skin covering the front of the helix and tragus.
A branch to the external auditory meatus (n. meatus auditorii externi) divides into
two. The two nerves enter the canal between the bony and cartilaginous portion
of the meatus. They supply the skin lining the meatus; the upper one sending
a filament to the membrana tympani (ramus membranae tympani).
A branch to the temporo-mandibular articulation, the articular branch, is usually
derived from the auriculo-temporal nerve.
The parotid branches (rami parotidei) supply the parotid gland.
The superficial temporal branches (rami temporales superficiales) accompany the
temporal artery to the vertex of the skull, and supply the integument of the tem-
poral region, communicating with the facial nerve, and with the temporal branch
of the temporo-malar from the superior maxillary.
The Lingual Nerve (n. lingualis) (Fig. 688). — The lingual nerve supplies the
papillae and mucous membrane of the anterior two-thirds of the tongue. It is
deeply placed throughout the whole of its course. It lies at first beneath the
External pterygoid muscle, together with the inferior dental nerve, being placed
to the inner side of this nerve, and is occasionally joined to it by a branch which
may cross the internal maxillary artery. The chorda tympani nerve also joins it
at an acute angle in this situation. The nerve then passes between the Internal
pterygoid muscle and the inner side of the ramus of the jaw, and crosses obliquely
to the side of the tongue over the Superior constrictor of the pharynx and the
Stylo-glossus muscles, and then between the Hyo-glossus muscle and the deep
part of the submaxillary r;land; the nerve finally runs across Wharton's duct, and
along the side of the tongue to its apex, lying immediately beneath the mucous
membrane.
The branches of communication are with the inferior dental and hypoglossal
nerves, and the submaxillary ganglion, and, apparently only, with the facial through
the chorda. The chorda tympani branch of the facial joins the lingual nerve under
the external pterygoid muscle and is distributed with the lingual to the tongue.
THE FIFTH, TRIGEMINAL OR TRIP ACT AL NERVE 1Q53
The hypoglossal nerve and the lingual nerve lie near together, over the Hyo-
glossus muscle, and the two nerves are joined by loops (rami anastomotici cum
it. hypoglosso). The branches to the submaxillary ganglion are two or three in
number; those connected with the hypoglossal nerve form a plexus at the anterior
margin of the Hyo-glossus muscle.
The branches of distribution supply the mucous membrane of the mouth, the
gums, the sublingual gland, the filiform and fungiform papillae and mucous mem-
brane of the tongue ; the terminal filaments communicate, at the tip of the tongue,
with the hypoglossaf nerve. The lingual fibres are fibres of common sensation.
The chorda tympani fibres which join the lingual nerve are probably taste-
fibres and excito-glandular for the submaxillary and sublingual salivary glands.
The Inferior Dental Nerve (n. alveolaris inferior) (Fig. 688). — The inferior
dental is the largest of the branches of the inferior maxillary nerve. It passes
downward with the inferior dental artery, at first beneath the External pterygoid
muscle, and then between the internal lateral ligament and the ramus of the jaw
to the dental foramen. It then passes forward in the dental canal of the inferior
maxillary bone, lying beneath the teeth, as far as the mental foramen, where it
divides into two terminal branches, incisor and mental.
The Branches of the inferior dental are: the mylo-hyoid, dental, incisor, and
mental.
The Mylo-hyoid (n. mylohyoideus] is derived from the inferior dental just as that
nerve is about to enter the dental foramen. It descends in a groove on the inner
surface of the ramus of the jaw, in which it is retained by a process of fibrous mem-
brane. It reaches the under surface of the Mylo-hyoid muscle, and supplies it and
the anterior belly of the Digastric.
The Dental Branches supply the molar and bicuspid teeth. They correspond
in number to the fangs of those teeth : each nerve entering the orifice at the point
of the fang and supplying the pulp of the tooth.
The Incisor Branch is continued onward within the bone to the middle line, and
supplies the canine and incisor teeth.
The dental branches and the incisor branch form a plexus (plexus dentalis infe-
rior}, and from this plexus come the branches to the teeth (rami dentales inferior es]
and to the gums (rami gingivales inferiores).
The Mental Branch (n. mentalis) emerges from the bone at the mental foramen,
and divides beneatWthe Depressor anguli oris muscle into two or three branches;
one descends to suAply the skin of the chin, and another (sometimes two) ascends
to supply the skin and mucous membrane of the lower lip. These branches com-
municate freely with the facial nerve.
Two small ganglia are connected with the inferior maxillary nerve — the otic
with the trunk of the nerve, and the submaxillary with its lingual branch.
Otic or Arnold's Ganglion (ganglion oticum) (Fig. 690). — The otic or Arnold's
ganglion is a small, oval-shaped, flattened ganglion of a reddish-gray color, situ-
ated immediately below the foramen ovale, on the inner surface of the inferior
maxillary nerve, and round the origin of the internal pterygoid nerve. It is in
relation, externally, with the trunk of the inferior maxillary nerve, at the point
where the motor root joins the sensor portion; internally, with the cartilaginous
part of the Eustachian tube, and the origin of the Tensor palati muscle; behind,
it lies in relation with the medidural artery.
Branches of Communication. — This ganglion is connected with the internal
pterygoid branch of the inferior maxillary nerve by two or three short delicate
filaments. From this nerve the ganglion may obtain a motor root, and possibly
also a sensor root, as these filaments from the nerve to the Internal pterygoid
perhaps contain sensor fibres. The otic ganglion communicates with the glosso-
pharyngeal and facial nerves through the small superficial petrosal nerve (Figs. 690
1054
THE NERVE SYSTEM
and 693) continued from the tympanic plexus, and through this communication
it probably receives its sensor root from the glosso-pharyngeal and its motor
root from the facial; its communication with the sympathetic is effected by a fila-
ment from the plexus surrounding the medidural artery. The ganglion also
communicates with the auriculo-temporal nerve (ramus anastomoticus cum n.
auriculotemporali). This communicating filament is probably a branch from the
glosso-pharyngeal which passes to the ganglion, and through it and the auriculo-
temporal nerve to the parotid gland. A slender filament, the sphenoidal, ascends
from it to the Vidian nerve.
Branches of Distribution. — Its branches of distribution are a filament to the
Tensor tympani (n. tensoris tympani} and one to the Tensor palati (n. tensoris veli
palatini). The former passes backward on the outer side of the Eustachian tube;
the latter arises from the ganglion, near the origin of the internal pterygoid nerve,
and passes forward. The fibres of these nerves are, however, mainly derived
from the nerve to the Internal pterygoid muscle. It also gives off a small com-
municating branch to the chorda tympani (ramus anastomoticus cum n. chorda
tympani).
FIG. 690. — The otic ganglion and its branches.
The Submaxillary Ganglion (ganglion submaxillare) (Fig. 688). — The submaxil-
lary ganglion is of small size, fusiform in shape, and situated above the deep
portion of the submaxillary gland, near the posterior border of the Mylo-hyoid
muscle, being connected by filaments with the lower border of the lingual nerve.
Branches of Communication. — This ganglion is connected with the lingual nerve
by a few filaments (rami communicantes cum n. linguaK), which join it separately
at its fore and back part. It also receives a branch from the chorda tympani, by
which it communicates with the facial, and communicates with the sympathetic
by filaments from the sympathetic plexus around the facial artery.
Branches of Distribution. — These are five or six in number; they arise from the
lower part of the ganglion, and supply the mucous membrane of the mouth and
Wharton's duct, some being lost in the submaxillary gland (rami submaxillares).
The branch of communication from the lingual nerve to the forepart of the gan-
glion is by some regarded as a branch of distribution, by which filaments of the
chorda tympani pass from the ganglion to the lingual nerve, and by it are con-
veyed to the sublingual gland and the tongue.
THE FIFTH, TRIGEMINAL OR TRIFAGIAL NERVE
1055
Summary of the Distribution and Connections of the Trigeminal Nerve. — It is the
chief sensor nerve of the face, the anterior half of the scalp, the mouth, nasal cavity,
lips, teeth, anterior two-thirds of the tongue, orbit, and eyeball. The clearly
defined cutaneous distributions of the branches are shown in Fig. 691. The
motor portion of the nerve supplies the muscles of mastication, the mylo-hyoid,
and the anterior belly of the digastric. By way of branches from the otic
ganglion it supplies the Tensor tympani and Tensor palati muscles, and by
way of branches from the spheno-palatine ganglion perhaps supplies the Levator
palati and Azygos uvulae muscles, although it is more probable that these muscles
receive their motor influence by the accessory nerves through the pharyngeal
plexus. The ganglia associated with the nerve create communications with the
sympathetic, the motor oculi, the facial, and the glosso-pharyngeal, and through
these ganglia, as Prof. Cunningham says, "important organs, areas, and muscles"
are innervated. The trigeminal communicates many times with the facial, and
thus gives sensor fibres to the "muscles of expression supplied by the facial
nerve."1
SUPRATROCHLEAR N.
SUPRAORBITAL N.
1NFRATROCHLEAR
NASAL NERVE
MENTAL NERVE
TEMPORAL BH.
OF TEMPORO-MALAR
MALAR BR. OF
TEMPORO-MALAR
AURICULO-TEMPORAL
NERVE
FIG. 691. — Sensor areas of the head, showing the general distribution of the three divisions of the fifth
nerve. Gerrish's Anatomy. (Modified from Testut.)
Surface Marking. — It will be seen from the above description that the three terminal branches
of the three divisions of the trigeminal nerve emerge from foramina in the bones of the skull and
pass on to the face: the terminal branch of the first division emerging through the supraorbital
foramen; that of the second through the infraorbital foramen; and the third through the mental
foramen. The supraorbital foramen is situated at the junction of the internal and middle
third of the supraorbital arch. If a straight line is drawn from this point to the lower border
of the inferior maxillary bone, so that it passes between the two bicuspid teeth of the lower jaw,
it will pass over the infraorbital and mental foramina, the former being situated about one
centimetre (two-fifths of an inch) below the margin of the orbit, and the latter varying in posi-
tion according to the age of the individual. In the adult it is midway between the upper and
lower borders of the inferior maxillary bone ; in the child it is nearer the lower border ; and in the
edentulous jaw of old age it is close to the upper margin.
Surgical Anatomy. — In fracture of the base of the skull the trigeminal nerve or one of its
branches may be injured. It seems certain that occasionally, though seldom, the trigeminal
nerve may be actually divided by such an injury. The trigeminal nerve may be affected in its
entirety, or its sensor or motor root may be affected, or one of its primary main divisions.
1 Cunningham's Text-book of Anatomy.
1056 THE NER VE SYSTEM
In injury to the sensor root there is anaesthesia of the half of the face on the side of the lesion,
with the exception of the skin over the parotid gland; insensibility of the conjunctiva, fol-
lowed, if the eye is not temporarily protected with a watch-glass, by destructive inflammation
of the cornea, partly, it is held, from loss of trophic influence, and partly, it is certain, from the
irritation produced by the presence of foreign bodies on it, which are not perceived by the
patient, and therefore not expelled by the act of winking; dryness of the nose, loss to a consider-
able extent of the sense of taste, and diminished secretion of the lacrimal and salivary glands.
In injury to the motor root there is impaired action of the lower jaw from paralysis of the muscles
of mastication on the affected side.
The trigeminal nerve is often the seat of neuralgia, and each of the three divisions has been
divided or a portion of the nerve excised for this affection. The supraorbital nerve may be ex-
posed by making an incision an inch and a half in length along the supraorbital margin below the
eyebrow, which is to be drawn upward, the centre of the incision corresponding to the supra-
orbital notch. The skin and Orbicularis palpebrarum having been divided, the nerve can be
easily found emerging from the notch and lying in some loose cellular tissue. It should be drawn
up by a blunt hook and divided, or, what is better, a portion of it should be removed. The
infraorbital nerve has been divided at its exit by an incision on the cheek; or the floor of the
orbit has been exposed, the infraorbital canal opened up, and the anterior part of the nerve
resected; or the whole nerve, together with Meckel's ganglion as far back as the foramen rotun-
dum, has been removed. This latter operation, though undoubtedly a severe proceeding, appears
to have been followed by better results than has nerve resection. The operation is performed
as follows: The superior maxillary bone is first exposed by a T-shaped incision, one limb of
the incision passing along the lower margin of the orbit, the other from the centre of the first
cut vertically down the cheek toward the angle of the mouth. The nerve is then found, is divided,
and a piece of silk is tied to it as a guide. A small trephine (one-half inch) is then applied
to the bone below, but including the infraorbital foramen, and the antrum opened. The
trephine is now applied to the posterior wall of the antrum, and the spheno-maxillary fossa
exposed. The infraorbital canal is now opened up from below by fine cutting-pliers or a
chisel, and the nerve drawn down into the trephine hole, it being held on the stretch by
means of the piece of silk; it is severed with fine curved scissors as near the foramen rotundum
as possible, any branches coming off from the ganglion being also divided.1 The mental
branch of the inferior .dental nerve may be divided at its exit from the foramen through an
incision made through the mucous membrane where it is reflected from the alveolar process on
to the lower lip ; or a portion of the trunk of the inferior dental nerve may be resected through
an incision on the cheek through the Masseter muscle, exposing the outer surface of the ramus of
the jaw. A trephine is then applied over the position of the inferior dental foramen and the
outer table removed, so as to expose the inferior dental canal. The nerve is dissected out of
the portion of the canal exposed, and, having been divided after its exit from the mental foramen,
it is by traction on the end exposed in the trephine-hole, drawn out entire, and cut off as high up
as possible.2 The inferior dental nerve has also been divided through an incision within the mouth,
the bony point guarding the inferior dental foramen forming the guide to the nerve. The buccal
nerve may be divided by an incision through the mucous membrane of the mouth and the Buc-
cinator muscle just in front of the anterior border of the ramus of the lower jaw (Stimson).
In inveterate neuralgia of one or two of the branches of the trigeminal nerve a peripheral opera-
tion may cure the case, but seldom does. It often gives relief, perhaps for months. In neuralgia
of the second division or third division, or of the second division and third division, Abbe, of
New York, opens the skull and divides the nerve or nerves by an intracranial operation,
removes a piece of nerve so as the foramen of exit is empty, and covers the foramen with rubber
tissue, to hinder regrowth of the nervel Other operators, after removing a piece from each
nerve, have plugged the foramina of the exit with dentists' cement or silver-foil.
Rose's method of neurectomy is very valuable for neuralgia of the second division. It is a
modification of the Braun-Lossen method. The infraorbital nerve is exposed, a ligature is
tied about it, the roof of the infraorbital canal is chiselled open, and the nerve is freed as far
back as possible. An incision is made from below the external angular process outward along
the zygoma to in front of the lobule of the ear, downward to just above the angle of the jaw,
and forward for two inches. The flap is raised and the zygoma is exposed. The root of the
zygoma is drilled at two points, and the zygomatic process of the temporal bone is drilled at two
points. The bone is sawed in two places between the drill-holes. The freed arch is lifted down
and back, the tendon of the temporal muscle is drawn backward, and the pterygo-maxillary
fossa is thus exposed. The internal maxillary artery is divided between two ligatures. The
External pterygoid muscle is separated from the greater wing of the sphenoid and from the root
of the external pterygoid process. The superior maxillary nerve is grasped and twisted off as
near the ganglion as possible. The entire nerve is then drawn back from the infraorbital foramen
and removed. The wound is then closed. If the third division is also haunted by neuralgia,
it too should be removed a few weeks after the performance of Rose's operation.
1 Carnochan, American Journal of the Medical Sciences, 1858, p. 136.
2 Mears, Transactions of the American Surgical Association, vol. ii, p. 469.
THE SIXTH OR ABDUCENT NERVE 1057
If a peripheral operation fails, or if all the branches of the trigeminal are involved, the Gasserian
ganglion must be removed or the sensor root of the trigeminal must be divided, as suggested by
Fru/ier and Spiller.
Removal of the Gasserian ganglion was suggested by J. Ewing Hears in 1884, and was first
carried out by Rose in 1890.
The method chiefly in vogue was devised by Hartley, and was first performed by him in 1891.
An osteoplastic flap is made in front of the ear, the dura is exposed and lifted. Following Krause's
advice, the third division is exposed and clamped. The second division is exposed and clamped.
The nerves are loosened from their beds and then are rolled about the clamps. This twisting
pulls out the ganglion intact along with the motor root, and also the sensor root from the pons.
A difficulty in the Hartley operation is the danger of division of the dural artery. If this
happens, the surgeon may be able to arrest bleeding and proceed with the operation. If the
vessel is torn off at the foramen spinosum, it will be necessary to pack the wound and postpone
any further operative manipulation for forty-eight hours.
Dr. Harvey Gushing has modified Hartley's operation by trephining the wall of the temporal
fossa very low down. He opens the skull below the arch of the dural vessels, and thus avoids the
medidural at the foramen spinosum, and also the sulcus arteriosus of the parietal bone.
After the removal of the ganglion, Professor Keen, in order to prevent undue inflammation of
the eye, sews the eyelids of the affected side together, leaving a space open at each angle, and
covers the eye with a watch-crystal. Boric acid solution is flushed into the opening at the external
angle at frequent intervals. The stitches are removed from the lid in from eight to ten days.
The lingual nerve is occasionally divided with the view of relieving the pain in cancerous
disease of the tongue. This may be done in that part of its course where it lies below and behind
the last molar tooth. If a line is drawn from the middle of the crown of the last molar tooth to
the angle of the jaw, it will cross the nerve, which lies about half an inch behind the tooth, par-
allel to the bulging alveolar ridge on the inner side of the body of the bone. If the knife is
entered three-quarters of an inch behind and below the last molar tooth and carried down to the
bone, the nerve will be divided. Hilton divided it opposite the second molar tooth, where
it is covered only by the mucous membrane, and Lucas pulls the tongue forward and over to the
opposite side, when the nerve can be seen standing out as a firm cord under the mucous mem-
brane by the side of the tongue and can be easily seized with a sharp hook and divided or a
portion excised. This is a simple enough operation on the cadaver, but when the disease is exten-
sive and has extended to the floor of the mouth, as is generally the case when division of the nerve
is thought of, the operation is not practicable.
THE SIXTH OR ABDUCENT NERVE (N. ABDUCENS) (Fig. 687).
The sixth or abducent nerve supplies the External rectus muscle. Its super-
ficial origin is by several filaments from the postpontile groove, between pons and
pyramid. Its deep origin is from the upper part of the floor of the fourth ven-
tricle, close to the median line, beneath the eminentia abducentis (Fig. 578).
From the nucleus of the abducent nerve some fibres are supposed to pass
through the medial longitudinal bundle to the oculomotor nucleus of the opposite
side and into the oculomotor nerve, along which they are carried to the Internal
rectus muscle. The External rectus of one eye and the Internal rectus of the
other may therefore be said to receive their nerves from the same nucleus — a
factor of great importance in connection with the conjugate movements of the
eyeball, and one that may explain certain paralytic phenomena of the Recti
muscles, which are often associated with lesions in the pons.
The nerve pierces the dura on the basilar surface of the sphenoid bone, runs
through a notch immediately below the posterior clinoid process, and enters the
cavernous sinus. It passes forward through the sinus, lying on the outer side
of the internal carotid artery (Fig. 454). It enters the orbit through the sphenoid
fissure, and lies above the ophthalmic vein, from which it is separated by a lamina
of dura (Fig. 692). It then passes between the two heads of the External rectus
muscle, and is distributed to that muscle on its ocular surface.
Branches of Communication. — It is joined by several filaments from the
carotid and cavernous plexuses, and by one from the ophthalmic nerve.
67
1058
THE NERVE SYSTEM
Frontal.
Relations to Each Other of the Oculomotor, Trochlear, Ophthalmic Division of the
Trigeminal and Abducent Nerves as they Pass to the Orbit. — The oculomotor,
trochlear, the ophthalmic division of the trigeminal, and the abducent nerves,
as they pass to the orbit, bear a certain relation to one another in the cavernous
sinus, at the sphenoidal fissure, and in the cavity of the orbit, which will now be
described.
In the Cavernous Sinus (Figs. 454 and 455) the oculomotor, trochlear, and
ophthalmic division of the trigeminal are placed on the outer wall of the sinus,
in their numerical order, both from above downward and from within outward.
The abducent nerve lies at the outer side of the internal carotid artery. As these
nerves pass forward to the sphenoidal fissure, the oculomotor and trigeminal
nerves become divided into branches, and the abducent nerve approaches the rest,
so that their relative position becomes considerably changed.
In the Sphenoidal Fissure (Fig. 692) the trochlear nerve and the frontal and
lacrimal branches of the ophthalmic division of the trigeminal lie upon the same
plane, the former being most internal, the latter external, and they enter the cavity
of the orbit above the muscles.
The remaining nerves enter
the orbit between the two heads
of the External rectus muscle.
The superior division of the
oculomotor nerve is the highest
of these; beneath this lies the
nasal branch of the ophthalmic
nerve; then the inferior division
of the oculomotor nerve; and
the abducent nerve lowest of
all.
In the Orbit (Figs. 683 and
687) the ' trochlear nerve and
the frontal and lacrimal divi-
sions of the ophthalmic nerve lie on the same plane immediately beneath the peri-
osteum, the trochlear nerve being internal and resting on the Superior oblique
muscle, the frontal nerve resting on the Levator palpebrae muscle, and the lacrimal
nerve on the External rectus muscle. Next in order comes the superior division
of the oculomotor nerve, lying immediately beneath the Superior rectus muscle,
and then the nasal branch of the ophthalmic nerve, crossing the optic nerve
from the outer to the inner side of the orbit. Beneath these is found the
optic nerve, surrounded in front by the ciliary nerves, and having the ciliary
ganglion on its outer side, between it and the External rectus muscle. Below the
optic nerve is the inferior division of the oculomotor nerve and the abducent
nerve, which lies on the outer side of the orbit.
Surgical Anatomy. — It is often stated that the abducent nerve is more frequently involved in
fractures of the base of the skull than any other of the cranial nerves. As a matter of fact, however,
it is injured in only about 2 per cent, of cases of fracture of the skull (Putscher). Cases have been
reported in which the nerve was actually ruptured. The nerve may be injured by traction,
pressure of a blood clot, of a tumor, or of an arterio-venous aneurism. The result of paralysis of
this nerve is internal or convergent squint. When injured so that its function is destroyed, there
is, in addition to the paralysis of the External rectus muscle, often a certain amount of contrac-
tion of the pupil, because some of the sympathetic fibres to the radiating muscle of the iris pass
along with this nerve.
Superior division of oculo-motor.
'/Nasal.
'Inferior division of oculo-motor.
^Abducent.
"Ophthalmic vein.
FIG. 692. — Relations of structures passing through
the sphenoidal fissure.
THE SEVENTH OR FACIAL NERVE 1059
THE SEVENTH OR FACIAL NERVE (N. FACIALIS) (Figs. 693, 694, 695).
The seventh or facial nerve is the motor nerve of all the muscles of expression
in the face, and of the Platysma and Buccinator; the muscles of the External ear;
the posterior belly of the Digastric, and the Stylo-hyoid. The chorda tympani
(or nervus intermedius) is referred to as the sensor portion of the facial.
Its superficial origin is from the upper end of the oblongata, in the groove
between the olive and restis. Its deep origin is from a nucleus situated in the
floor of the fourth ventricle, beneath the superior fovea (Fig. 578). The facial
nucleus is deeply placed in the
reticular formation of the lower
part of the preoblongata, a little External petrot
external and ventral to the nucleus |™^ Jgggg ffiroTai-
of the abducent nerve. From this Intumescentia ganglioformis.
origin the fibres pursue a curved
course in the substance of the pre-
oblongata. They first pass back-
ward and inward, and then turn FlG- 693--The co^r^iea^mc^rnaf £°nneof the facial nerve
upward and forward, forming the
fasciculus teres, which with the nucleus abducentis produces an eminence, the
eminentia abducentis, on the floor of the fourth ventricle, and finally bend sharply
downward and outward around the upper end of the nucleus of origin of the
abducent nerve, to reach their superficial origin between the olive and rectis.
From the nucleus of the oculomotor nerve some fibres arise which descend in
the medial longitudinal bundle and join the facial just before it leaves the pre-
oblongata; these fibres are said to supply the anterior belly of the Occipito-
frontalis, the Orbicularis palpebrarum, and the Corrugator supercilii, as these
muscles have been observed to escape paralysis in lesions of the nucleus of the
facial nerve.
The acoustic or auditory nerve lies to the outer side of the facial nerve ; and between
the two is a small fasciculus, the nervus intermedius or pars intermedia of Wrisberg,
which apparently arises from the oblongata and joins the facial nerve in the internal
auditory meatus. The central processes of the ganglion cells, known as the nervus
intermedius, end in the upper end of the nucleus of the glosso-pharyngeal nerve.
The nervus intermedius may be regarded as the sensor root of the facial nerve,
analogous to the sensor root of the trigeminal, and its real nucleus of origin
consists of the geniculate ganglion (see p. 894).
The facial nerve, firmer, rounder, and smaller than the auditory, passes forward
and outward upon the medipeduncle of the cerebellum, and enters the internal
auditory meatus with the, auditory nerve. Within the meatus the facial nerve
lies in a groove along the upper and anterior part of the auditory nerve, and the
nervus intermedius is placed between the two and joins the inner angle of the
geniculate ganglion. Beyond the ganglion its fibres are generally regarded as
forming the chorda tympani (see p. 894).
At the bottom of the meatus the facial nerve enters the aquaeductus Fallopii
and follows the course of that canal through the petrous portion of the temporal
bone, from its commencement at the internal meatus to its termination at the stylo-
mastoid foramen (Figs. 49 and 693). It is at first directed outward between the
cochlea and vestibule toward the inner wall of the tympanum ; it then bends sud-
denly backward and arches downward behind the tympanum to the stylo-mastoid
foramen. At the point in the aqueduct of Fallopius where the nerve changes its
direction (geniculum n. facialis), it presents a reddish, gangliform swelling, the
geniculate ganglion (ganglion geniculi), which is also called the intumescentia ganglio-
1000
THE NERVE SYSTEM
In the internal auditory meatus .
formis (Fig. 693). The geniculate ganglion receives a branch from the vestibular
division of the auditory nerve. On emerging from the stylo-mastoid foramen
the facial nerve runs forward in the substance of the parotid gland, crosses the
external carotid artery, and divides behind the ramus of the lower jaw into two
primary branches, temporo-facial and cervico-facial, from which numerous offsets
are distributed over the side of the head, face, and upper part of the neck,
supplying 'the superficial muscles in these regions. As the primary branches and
their offsets diverge from each other, they present somewhat the appearance of a
bird's claw; hence the name of pes anserinus is given to the divisions of the facial
nerve in and near the parotid gland.
Branches of Communication (Fig. 694). — The communications of the facial
nerve may be thus arranged:
With the acoustic nerve. The nervus
intermedius, which is between the
facial and acoustic, is supposed to give
branches to both. The branch given
to the acoustic accompanies it for a
certain distance, and then departs
from it to join the geniculate ganglion.
With the acoustic as explained above.
With the spheno-palatine ganglion by
the large superficial petrosal nerve.
With the otic ganglion by the small
superficial petrosal nerve.
With the sympathetic on the medi-
dural artery by the external super-
ficial petrosal nerve.
With the auricular branch of the vagus.
With the glosso-pharyngeal.
With the vagus.
With the auricularis magnus.
With the auriculotemporal.
With the small occipital.
With three divisions of the trigeminal.
With the superficial cervical.
From the geniculate ganglion .
In the Fallopian aqueduct
At its exit from the stylomastoid
foramen
Behind the ear .
On the face .
In the neck .
In the internal auditory meatus some minute filaments pass between the facial
and acoustic nerves.
Opposite the hiatus Fallopii the gangliform enlargement on the facial nerve
communicates with the spheno-palatine ganglion by means of the large superficial
petrosal nerve, which forms its motor root; with the o^ic ganglion, by the small
superficial petrosal nerve; and with the sympathetic filaments accompanying the
medidural artery, by the external petrosal nerve (Bidder). From the gangliform
enlargement, according to Arnold, a twig is sent back to the acoustic nerve. Just
before the facial nerve emerges from the stylo-mastoid foramen it generally receives
a twig of communication from the auricular branch of the vagus.
After its exit from the stylo-mastoid foramen, it sends a twig to the glosso-
pharyngeal, another to the vagus nerve, and communicates with the great auric-
ular branch of the cervical plexus, with the auriculo-temporal branch of the
inferior^ maxillary nerve in the parotid gland, with the small occipital nerve
behind the ear, on the face with the terminal branches of the three divisions of
the trigeminal, and in the neck with the transverse cervical.
Branches of Distribution (Fig. 694). — The branches of distribution of the
facial nerves may be thus arranged:
THE SEVENTH OR FACIAL NERVE
1061
f Tvmpanic, to the Stapedius muscle.
\\ithm the aquaeductus Fallopn . j ^^ tympani.
( Posterior Auricular.
At its exit from the stylo-mastoid I j)jffas^rjc
foramen •" •'• ' \Stylo-hyoid.
( Temporal.
( Temporo-facial . < Malar.
( Infraorbital.
On the face 1
L Cervico-facial
( Buccal.
Supramaxillary.
Inframaxillary.
The branches of the two terminal divisions form the paxotid plexus (plexus
parotideus).
The Tympanic Branch (n. stapedius) (Fig. 694). — The tympanic branch arises
from the nerve opposite the pyramid ; it passes through a small , canal in the
pyramid and supplies the Stapedius muscle.
Nucleus Salivatortua
Superior Maxillary X
Vidian N.
To Auricular
Branch of I'ayus .V.
Post
Auricular Br.
To Digastric
To Stylo-hyoid
Infraorbital
Buccal
Supramaxillary
Imframaxillary
Afferent (taste) fiben
Efferent (excito^landular)
fibers to submaxillary and
sublingual ganglia and glands
FIG. 694. — Plan of the facial and intermediate nerves and their communication with other nerves.
The Chorda Tympani (Figs. 688, 693, and 694). — The chorda tympani is appar-
ently given off from the facial as it passes vertically downward at the back of the
tympanum, about 5 mm. before its exit from the stylo-mastoid foramen. It
passes from below upward and forward in a distinct canal, and enters the cavity
of the tympanum through an aperture (Her chordae posierius] on its posterior wall
between the opening of the mastoid cells and the attachment of the membrana
tympani, and becomes invested with mucous membrane. It passes forward through
the cavity of the tympanum, between the fibrous and mucous layers of the mem-
brana tympani, and over the handle of the malleus, emerging from that cavity
1062 THE NERVE SYSTEM
through a foramen at the inner end of the Glaserian fissure, which is called the
canal of Huguier (iter chordae anterius). It then descends between the two
Pterygoid muscles, meets the lingual nerve at an acute angle, and accompanies
it to the submaxillary gland; part of it then joins the submaxillary ganglion; the
rest is continued onward through the muscular substance of the tongue to the
mucous membrane covering its anterior two-thirds. A few of its fibres probably
pass through the submaxillary ganglion to the sublingual gland. Before joining
the lingual nerve it receives a small communicating branch from the otic ganglion.
As already stated, the chorda tympani nerve is regarded as the peripheral con-
tinuation of the nervus intermedius (see p. 894).
The Posterior Auricular Nerve (n. auricularis posterior) (Figs. 655, 694, and
695). — The posterior auricular nerve arises close to the stylo-mastoid foramen,
and passes upward in front of the mastoid process and between the mastoid pro-
cess and the external ear, where it is joined by a filament from the auricular
branch of the vagus, and communicates with the mastoid branch of the great
auricular and with the small occipital. As it ascends between the external auditory
meatus and the mastoid process it divides into two branches, the auricular and
the occipital branches.
The Auricular Branch supplies the Retrahens auriculam and the small muscles
on the cranial surface of the pinna.
The Occipital Branch (ramus occipitalis] , the larger, passes backward along the
superior curved line of the occipital bone, and supplies the occipital portion of the
Occipito-frontalis.
The Digastric Branch of the Facial Nerve (ramus digastricus). — The digastric
branch usually arises by a common trunk with the Stylo-hyoid branch; it divides
into several filaments, which supply the posterior belly of the Digastric; one of
these perforates that muscle to join the glosso-pharyngeal nerve (ramus anasto-
moticus cum n. glossopharyngeo) .
The Stylo-hyoid Branch (ramus stylohyoideus}. — The stylo-hyoid branch is a
long, slender branch, which passes inward, entering the Stylo-hyoid muscle about
its middle.
The Temporo-facial Division (Figs. 694 and 695). — The tempo ro-facial, the larger
of the two terminal branches of the facial, passes upward and forward through
the parotid gland, crosses the external carotid artery and temporo-maxillary vein,
and passes over the neck of the condyle of the jaw, being connected in this situation
with the auriculo-temporal branch of the inferior maxillary nerve, and divides
into branches which are distributed over the temple and upper part of the face;
these are divided into three sets — temporal, malar, and infraorbital.
The Temporal Branches (rami temporales] cross the zygoma to the temporal
region, supplying the Attrahens and Attollens auriculam muscles, and join \vith
the temporal branch of the temporo-malar division of the superior maxillary,
and \vith the auriculo-temporal branch of the inferior maxillary. The more ante-
rior branches supply the frontal portion of the Occipito-frontalis, the Orbicularis
palpebrarum, and Corrugator supercilii muscles, joining with the supraorbital
and lacrimal branches of the ophthalmic.
The Malar Branches (rami zygomatici) pass across the malar bone to the outer
angle of the orbit, where they supply the Orbicularis palpebrarum muscle, join-
ing with filaments from the lacrimal nerve; others supply the lower eyelid,
joining with filaments of the malar branch (subcutaneus malae) of the superior
maxillary nerve.
The Infraorbital Branches (rami buccales), of larger size than the rest of the malar
branches, pass horizontally forward to be distributed between the lower margin of
the orbit and the mouth. The superficial branches run beneath the skin and
above the superficial muscles of the face, which they supply; some branches are
THE SEVENTH OR FACIAL NERVE
1063
distributed to the Pyramidalis nasi, joining at the inner angle of the orbit with the
infratrochlear and nasal branches of the ophthalmic. The deep branches pass
beneath the Zygomatici and the Levator labii superioris, supplying the Levator
anguli oris, the Levator labii superioris alaeque nasi and the small muscles of the
nose, and form a plexus, infraorbital plexus, by joining with the branches of the
infraorbital branch of the superior maxillary nerve and the buccal branches of
the cervico-facial.
Terminations
of supratrochlear.
)f infratrochlear
of nasal.
FIG. 695. — The nerves of the scalp, face, and side of the neck.
The Cervico-facial Division. — The cervi'co-facial division of the facial nerve
passes obliquely downward and forward through the parotid gland, crossing the
external carotid artery. In this situation it is joined by branches from the great
auricular nerve. Opposite the angle of the lower jaw it divides into branches
which are distributed on the lower half of the face and upper part of the neck.
These may be divided into three sets — buccal, supramaxillary, and inframaxillary.
The Buccal Branches (rami buccales) cross the Masseter muscle. They supply
the Buccinator and Orbicularis oris, and join with the infraorbital branches of
the temporo-facial division of the nerve, and with filaments of the buccal branch
of the inferior maxillary nerve.
The Supramaxillary or Supramandibular Branch (ramus marginalis mandibulae)
passes forward beneath the Platysma and Depressor anguli oris, supplying the
1064 THE NERVE SYSTEM
muscles of the lower lip and chin, and communicating with the mental branch of
the inferior dental nerve.
The Inframaxillary, Inframandibular or Cervical Branch (ramus colli) runs for-
ward beneath the Platysma, and forms a series of arches across the side of the
neck over the suprahyoid region. A branch descends vertically to join with the
superficial cervical nerve from the cervical plexus; others supply the Platysma.
Surgical Anatomy. — The facial nerve is more frequently paralyzed than any of the other
of the cranial nerves. The paralysis may depend either upon (1) central causes — i. e., blood-clots
or intracranial tumors pressing on the nerve before its entrance into the internal auditory meatus.
It is also one of the nerves involved in bulbar paralysis. Or (2) it may be paralyzed in its pass-
age through the petrous bone by damage due to middle-ear disease or by fractures of the base.
Or (3) it may be affected at or after its exit from the stylo-mastoid foramen. This is commonly
known as Bell's paralysis. It may be due to exposure to cold or to injury of the nerve, either
from accidental wounds of the face or during some surgical operation, as removal of parotid
tumors, opening of abscesses, or operations on the lower jaw.
When the cause is central, the abducent nerve is usually paralyzed as well, and there is also hemi-
plegia on the opposite side. In these cases the electric reactions are the same as in health;
whereas, when the paralysis is due to a lesion in the course of the nerve, the reactions of degenera-
tion develop. When the nerve is paralyzed in the petrous bone, in addition to the paralysis of the
muscles of expression, there is loss of taste in the anterior part of the tongue, and the patient is
unable to recognize the difference between bitters and sweets, acids and salines, from involvement
of the chorda tympani. The mouth is dry, because the salivary glands are not secreting; the sense
of hearing is affected from paralysis of the Stapedius, but there is no hemiplegia. When the
cause of the paralysis is from fracture of the base of the skull, the acoustic nerve and the petrosal
nerves, which are connected with the intumescentia ganglioformis, are also involved. When
the injury to the nerve is after its exit from the stylo-mastoid foramen, all the muscles of-expression
except the Levator palpebrse, tpgether with the posterior belly of the Digastric and Stylo-hyoid,
are paralyzed. There is smoothness of the forehead, and the patient is unable to frown; the
eyelids cannot be closed, and the lower lid droops, so that the punctum is no longer in contact
with the globe, and the tears run down the cheek; there is smoothness of the cheek and loss of
the nasolabial furrow; the nostril of the paralyzed side cannot be dilated; the mouth is drawn
to the sound side, and there is inability to whistle; food collects between the cheek and gum
from paralysis of the Buccinator.
The facial nerve is at fault in cases of so-called histrionic spasm, which consists in an almost
constant and uncontrollable twitching of the muscles of the face. This twitching is sometimes
so severe as to cause great discomfort and annoyance to the patient and to interfere with sleep,
and for its relief the facial nerve has been stretched. The operation is performed by making an
incision behind the ear from the root of the mastoid process to the angle of the jaw. The
parotid is turned forward, and the dissection carried along the anterior border of the Sterno-
mastoid muscle and mastoid process until the upper border of the posterior belly of the Digas-
tric is found. The nerve is parallel to this on about a level with the middle of the mastoid process.
When found, the nerve may be stretched by passing a blunt hook beneath it and pulling it for-
ward and outward. Too great force must not be used, for fear of permanent injury to the nerve.
In facial palsy of extracerebral origin it may be advisable to expose the nerve, cut it across, and
anastomose the distal end of the paralyzed nerve to the accessory nerve or, better, to the hypo-
glossal nerve (facio-accessory anastomosis or facio-hypoglossal anastomosis). The idea was first
proposed by Ballance, and has been put in practice by Ballance and Stewart, Keen, Gushing,
Faure, Kennedy, and others.
THE EIGHTH OR ACOUSTIC NERVE (N. ACUSTICUS) (Fig. 696).
The eighth or acoustic or auditory nerve comprises two distinct sets of fibres
which, although both are devoted to the transmission of afferent impulses, differ
in their peripheral distribution and in their central connections. The two divisions
appear blended in the interval between the oblongata and the internal auditory
meatus, running oblique latero-frontad in company with the facial nerve and
internal auditory artery. At the internal auditory meatus the two divisions of
the nerve are separable, the vestibular division above, the cochlear below.
The Cochlear Nerve (radix cochlearis) . — The cochlear nerve is the true nerve of
hearing, lacking general sensibility, however, and therefore a nerve of special sense.
THE EIGHTH OR ACOUSTIC NERVE
1065
The fibres of this division arise from the cells of the spiral ganglion of the cochlear
as axones of bipolar cells whose dendrites or peripheral processes terminate about
the (auditory) hair-cells of the organ of Corti. The central connections of the
cochlear division are described on p. 892.
The Vestibular Nerve (radix vestibularis}. — The vestibular nerve conducts
impulses of equilibratory-sense from the semicircular canals, utricle, and saccule to
the vestibular nuclei. The ganglion of origin of this nerve differs from ordinary
sensor ganglia in that its cells are of bipolar structure, having retained this
embryonic characteristic of the ganglion-cells throughout life. The central
processes of the cells of the vestibular ganglion (or ganglion of Scarpa) enter the
oblongata with the trunk of the cochlear nerve in the postpontile groove, laterad
of the facial nerve, to establish central connections already described on p. 893.
The peripheral processes constitute the two main branches of the nerve, viz.,
(a) the utricujb-ampullar and (6) the sacculo-ampullar.
FIG. 696. — Distribution of the acoustic nerve. (Semidiagrammatic.) (Testut.)
The upper or utriculo-ampullar branch divides into:
(a) The Utricular Branch, passing through the superior macula cribrosa of the
vestibule to end in the macula acustica of the utricle.
(b) The Superior Ampullar Branch, accompanying the utricular branch, to end
in the crista acustica of the ampulla of the superior semicircular canal.
(c) The Lateral Ampullar, to the ampulla of the lateral semicircular canal.
The lower or sacculo-ampullar branch is somewhat longer and divides into:
(a) The Posterior Ampullar, passing through the foramen singulare and the
inferior macula cribrosa to end in the ampulla of the posterior semicircular canal.
(6) The Saccular Branch, passing through the middle macula cribrosa to end in
the macula acustica of the sacculus.
Surgical Anatomy. — The acoustic nerve is frequently injured, together with the facial nerve,
in fractures of the middle fossa of the base of the skull implicating the internal auditory meatus.
The nerve may be either torn across, producing permanent deafness, it may be bruised or it may
be pressed upon by extra vasated blood or inflammatory exudation, when the deafness will in all
probability be temporary. The nerve may also be injured by violent blows on the head without
1066 THE NER VE SYSTEM
fracture, and deafness may follow loud explosions of dynamite, etc., probably from some lesion
of this nerve, which is more liable to be injured than the other cranial nerves on account of
its structure. The test that the nerve is destroyed and that the deafness is not due to some
lesion of the auditory apparatus is obtained by placing a vibrating tuning-fork on the head.
The vibrations will be heard in cases where the auditory apparatus is at fault, but not in cases
of destruction of the auditory nerve.
THE NINTH OR GLOSSO-PHARYNGEAL NERVE (N. GLOSSOPHARYNGEUS)
(Figs. 697 and 698).
' The ninth or glosso-pharyngeal nerve is distributed, as its name implies, to
the tongue and pharynx, being the nerve of ordinary sensation to the mucous
membrane of the pharynx, fauces, and tonsil ; and the nerve of taste to all parts of
the tongue to which it is distributed.
Its (apparent) superficial origin is by three or four filaments, closely connected
together, from the upper part of the oblongata, in the dorso-lateral groove (Fig. 697) .
The central connections are described on p. 890. The small motor component
arises from cells in the nucleus ambiguus. The real origin of the sensor fibres
of the glosso-pharyngeal must be looked for in the
"^ L jugular and petrosal ganglia which are developed
from the neural crest.
From its superficial origin it passes outward across
the flocculus, and leaves the skull at the central part
of the jugular foramen, in a separate sheath of the
dura external to and in front of the vagus and ac-
cessory nerves (Fig. 698). In its passage through
the jugular foramen it grooves the lower border of
the petrous portion of the temporal bone, and at its
. ^ from.the sku11 Pass.es forward between the jugular
eleventh cranial nerves. vein and internal carotid artery, and descends ventrad
of the latter vessel, and beneath the styloid process
of the temporal bone and the muscles connected with it, to the lower border of the
Stylo-pharyngeus muscle. The nerve now curves inward, forming an arch on the
side of the neck, and lying upon the Stylo-pharyngeus muscle and the Middle
constrictor of the pharynx. It then passes beneath the Hyo-glossus muscle, and
is finally distributed to the mucous membrane of the fauces and base of the
tongue, and the mucous glands of the mouth and tonsil.
In passing through the jugular foramen the nerve presents, in succession, two
gangliform enlargements. The superior and smaller is called the jugular ganglion;
the inferior and larger, the petrous ganglion or the ganglion of Andersch.
The Superior or Jugular Ganglion (Ganglion Superius n. Glossopharyngei).
The superior or jugular ganglion is situated in the upper part of the groove in
which the nerve is lodged during its passage through the jugular foramen. It is
of very small size, and involves only the lower part of the trunk of the nerve. It
is usually regarded as a segmentation from the lower ganglion.
The Inferior or Petrous Ganglion (Ganglion Petrosum n. Glossopharyngei)
(Fig. 697).
The inferior or petrous ganglion is situated in a depression in the lower border of
the petrous portion of the temporal bone; it is larger than the superior ganglion and
involves the whole of the fibres of the nerve. From this ganglion arise those fila-
ments which connect the glosso-pharyngeal with the vagus and sympathetic nerves.
THE NINTH OR GLOSSO-PHARYNGEAL NERVE 1Q67
Branches of Communication. — The branches of communication are with the
va^us, sympathetic, and facial.
The branches to the vagus are two filaments, arising from the petrous ganglion,
one of which passes to the auricular branch of the vagus, and one to the upper
ganglion of the vagus.
The branch to the sympathetic, also arising from the petrous ganglion, is con-
nected with* the superior cervical ganglion.
The branch of communication with the facial perforates the posterior belly of
the Digastric muscle. It arises from the trunk of the nerve below the petrous
ganglion, and joins the facial just after its exit from the stylo-mastoid foramen.
Branches of Distribution. — The branches of distribution are the tympanic,
carotid, pharyngeal, muscular, tonsillar, and lingual.
The Tympanic Branch or Jacobson's Nerve (n. tympanicus). — The tympanic branch
or Jacobson's nerve arises from the petrous ganglion, and enters a small bony
canal in the lower surface of the petrous portion of the temporal bone, the lower
opening of which is situated on the bony ridge which separates the carotid canal
from the jugular fossa. It ascends to the tympanum, enters that cavity by an
aperture in its floor close to the inner wall, and divides into branches which are
contained in grooves upon the surface of the promontory. These branches form
a tympanic plexus (plexus tympanicus). This plexus gives off (1) the greater
part of the small superficial petrosal nerve (Fig. 694); (2) a branch to join the
great superficial petrosal nerve; and (3) branches to the tympanic cavity, all of
which will be. described in connection with the anatomy of the ear.
The Carotid Branches (n, caroticotympanicus superior and n. caroticotympanicus
inferior). — The carotid branches descend along the trunk of the internal carotid
artery as far as its commencement, communicating with the pharyngeal branch
of the vagus and with branches of the sympathetic.
The Pharyngeal Branches (rami pharyngei). — The pharyngeal branches are three
or four filaments which unite opposite the Middle constrictor of the pharynx with
the pharyngeal branches of the vagus and sympathetic nerves to form the pharyn-
geal plexus, branches from which perforate the muscular coat of the pharynx to
supply the muscles and mucous membrane.
The Muscular Branch (ramus stylopharyngeus). — The muscular branch is dis-
tributed to the Stylo-pharyngeus muscle.
The Tonsillar Branches (rami tonsillares). — The tonsillar branches supply the
tonsil, forming a plexus (circulus tonsillaris) around this body, from which .
branches are distributed to the soft palate and fauces, where they communicate
with the palatine nerves.
The Lingual Branches (rami linguales). — The lingual branches are two in num-
ber : one supplies the circumvallate papillae and the mucous membrane covering
the surface of the base of the tongue; the other perforates its substance, and
supplies the mucous membrane and follicular glands of the posterior one-third
of the tongue and communicates with the lingual nerve.
The Gustatory Path. — The impressions of taste reach the glosso-pharyngeal
nucleus in the oblongata in two ways. From the posterior one-third of the tongue
and from the palate they reach the nucleus by the glosso-pharyngeal nerve. From
the anterior two-thirds of the tongue impulses of taste are conveyed by the chorda
tympani and nervus intermedius. From the glosso-pharyngeal nucleus gustatory
impressions pass by way of the medial fillet to the thalamus of the opposite side,
and from the thalamus through ventral thalamo-cortical radiation to the gyrus
hippocampi, where the cortical gustatory centre is situated.
Surgical Anatomy. — Injury may produce hemorrhage about the roots of the nerve. Berg-
mann reported such a case. The patient died from o?dema of the glottis after presenting
evidences of disorder of speech and difficulty in swallowing.
1068
THE NERVE SYSTEM
Glosso-pharyngeal.
Vagus.
Accessory.
THE TENTH, VAGUS OR PNEUMOGASTRIC NERVE (N. VAGUS).
(Figs. 697 and 698).
The tenth, vagus or pneumogastric nerve has a more extensive distribution
than any of the other cranial nerves, passing through the neck and thorax to the
upper part of the abdomen. It
is composed of both motor and
sensor fibres. It supplies the
organs of voice and respiration
with motor and sensor fibres, and
the pharynx, oesophagus, stom-
ach, and heart with motor fibres.
Its superficial origin (Fig. 697)
is by eight or ten filaments from
the groove between the olive and
the restis below the glosso-phar-
yngeal; its central connections
are described on p. 890.
The real origin of the sensor
fibres of the vagus is to be found
in the cells of the ganglia on the
nerve — viz., the ganglion of the
root and the ganglion of the
trunk. The filaments become
united and form a flat cord,
which passes outward beneath
the flocculus to the jugular fora-
men, through which it emerges
from the cranium (Fig. 698). In
passing through this opening the
vagus accompanies the accessory
nerve, being contained in the
same sheath of dura with it, a
membranous septum separating
them from the glosso-pharyngeal,
which lies in front (Fig. 698).
The nerve in this situation pre-
sents a well-marked ganglionic
enlargement, which is called the
superior ganglion, or jugular gan-
glion; to it the vagal accessory
part of the accessory nerve is
connected by one or two fila-
ments. After the exit of the
nerve from the jugular foramen
the nerve is joined by the acces-
sory portion of the accessory
nerve and enlarges into a second
gangliform swelling, called the
inferior ganglion or the ganglion
of the trunk of the nerve, through
which the fibres of the accessory
FIG. 698.— Course and distribution of the glosso-pharyngeal, nprVP nass Unchanged being
vagus, and accessory nerves.
THE TENTH OR VAGUS NERVE 1069
principally distributed to the pharyngeal and superior laryngeal branches of the
vagus; but some of the filaments from it are continued into the trunk of the
vagus below the ganglion to be distributed with the recurrent laryngeal nerve,
and probably also with the cardiac nerves. The vagus nerve passes vertically
down the neck within the sheath of the carotid vessels lying between the inter-
nal carotid artery and the internal jugular vein as far as the thyroid cartilage,
and then between the same vein and the common carotid to the root of the neck
(Fig. 698). From here the course of the nerve differs on the two sides of the
body.
On the right side (Fig. 698) the nerve passes across the subclavian artery between
it and the right innominate vein, and descends by the side of the trachea to the back
part of the root of the lung, where it spreads out in a plexiform network, the
dorsal pulmonary plexus (plexus pidmonalis posterior), from the lower part of which
two cords descend upon the oesophagus, on which tube they divide, forming, with
branches from the opposite nerve, the oesophageal plexus (plexus gulae) ; below, these
branches are collected into a single cord, which runs along the back part of the
oesophagus, enters the abdomen, and is distributed to the dorsal surface of
the stomach, joining the left side of the solar plexus, and sending filaments to the
splenic plexus and a considerable branch to the coeliac plexus.
On the left side the vagus nerve enters the chest between the left carotid and
subclavian arteries, behind the left innominate vein. It crosses the arch of
the aorta and descends behind the root of the left lung, forming the ventral pul-
monary plexus (plexus pidmonalis anterior), and along the ventral surface of the
oesophagus, where it unites with the nerve of the right side in forming the oesopha-
geal plexus. It passes to the stomach, distributing branches over the ventral
surface of that viscus, some extending over the great cul-de-sac, and others along
the lesser curvature. Filaments from these branches enter the gastro-hepatic
omentum and join the hepatic plexus.
The Ganglion of the Eoot of the Vagus Nerve (Ganglion Jugulare).
The ganglion of the root or the jugular ganglion is of a grayish color, circular
in form, about two lines in diameter, and resembles the ganglion on the larger
root of the fifth nerve.
Connecting Branches. — To this ganglion the accessory portion of the ac-
cessory nerve is connected by several delicate filaments; it also has a com-
municating twig with the petrous ganglion of the glosso-pharyngeal, with the
facial nerve by means of its (the ganglion's) auricular branch, and with the
sympathetic by means of an ascending filament from the superior cervical
ganglion.
The Ganglion of the Trunk of the Vagus Nerve (Ganglion Nodosum).
The ganglion of the trunk or the inferior ganglion is a plexiform cord, cylin-
drical in form, of a reddish color, and about an inch (2 cm.) in length; it involves
the whole of the fibres of the nerve, and passing through it is the accessory
portion of the accessory nerve, which blends with the vagus below the ganglion,
to be then continued principally into its pharyngeal and superior laryngeal
branches.
Connecting Branches. — This ganglion is connected with the hypoglossal, the
superior cervical ganglion of the sympathetic, and the loop between the first and
second cervical nerves.
1070 THE NERVE SYSTEM
The branches of the vagus are —
In the jugular fossa
In the neck ...
In the thorax
In the abdomen
f Dural.
\ Auricular.
f Pharyngeal.
I Superior laryngeal.
I Recurrent laryngeal.
L Cervical cardiac,
f Thoracic cardiac.
I Ventral pulmonary.
I Dorsal pulmonary.
I (Esophageal.
Gastric.
The Dural Branch (ramus meningeus). — The dural branch is a recurrent fila-
ment given off from the ganglion of the root in the jugular foramen. It passes
backward^ and is distributed to the dura lining the posterior fossa of the base of
the skull.
The Auricular Branch or Arnold's Nerve (ramus auricularis) (Fig. 699). — The
auricular branch or Arnold's nerve arises from the ganglion of the root, and is
joined soon after its origin by a filament from the petrous ganglion of the glosso-
pharyngeal; it passes outward behind the jugular vein, and enters a small canal
on the outer wall of the jugular fossa. Traversing the substance of the tem-
poral bone, it crosses the aquaeductus Fallopii about two lines above its termina-
tion at the stylo-mastoid foramen; here it gives off an ascending branch, which
joins the facial; the continuation of the nerve reaches the surface by passing
through the auricular fissure between the mastoid process and the external audi-
tory meatus, and divides into two branches, one of which communicates with the
posterior auricular nerve, while the other supplies the integument at the back
part of the pinna and the dorsal part of the external auditory meatus.
TO EXTERNAL AUDITORY
US AND
\(OF
TO POSTERIOR
AURICULAR OF
FACIAL
FROM GLOSSOPHARYNGEAL
AURICULAR BRANCH
OF VAGUS
1°
ARTERIOSUS X •
FIG. 700. — Relations of vagus and recurrent
FIG. 699.— Plan of Arnold's nerve. (W. Keiller.)
The Pharyngeal Branch (ramus pharyngeus).
—The pharyngeal branch, the principal
motor nerve of the pharynx, arises from the
upper part of the ganglion of the trunk of the
VagUS. It Consists principally of filaments laryngeal nerves to the great vessels. (W.
from the accessory portion of the accessory Keiller>)
nerve; it passes across the internal carotid artery to the upper border of the
Middle constrictor of the pharynx, where it divides into numerous filaments which
join with those from the glosso-pharyngeal, the superior laryngeal (its external
branch), and sympathetic, to form the pharyngeal plexus (plexus pharyngeus},
THE TENTH OR VAGUS NERVE 1071
from which branches are distributed to the muscles and mucous membrane of
the pharynx and the muscles of the soft palate. From the pharyngeal plexus a
minute filament is given off, which descends and joins the hypoglossal nerve as
it winds around the occipital artery.
The Superior Laryngeal Nerve (n. laryngeus superior] (Figs. 697 and 698). — It is
larger than the preceding, and arises partly from the middle of the ganglion of the
trunk of the vagus. It consists principally of filaments from the accessory nerve.
In its course it receives a branch from the superior cervical ganglion of the sympa-
thetic. It descends by the side of the pharynx behind the internal carotid artery,
where it divides into two branches, the external and internal laryngeal. This nerve
is the nerve of sensation of the larynx, and also supplies the crico-thyroid muscle.
Exner has pointed out that the superior laryngeal nerve innervates to some ex-
tent the muscles supplied by the inferior laryngeal, and this fact explains why
division of the inferior laryngeal nerve is not of necessity followed by complete
paralysis of the muscles it supplies.
The External Laryngeal Branch of the Superior Laryngeal (ramus externus) (Fig.
698), the smaller, descends by the side of the larynx, beneath the Sterno-thyroid,
to supply the Crico-thyroid muscle. It gives branches to the pharyngeal plexus
and the Inferior constrictor, and communicates with the superior cardiac nerve,
behind the common carotid.
The Internal Laryngeal Branch of the Superior Laryngeal (ramus internus)
descends to the opening in the thyro-hyoid membrane, through which it passes
with the superior laryngeal artery, and is distributed to the mucous membrane of
the larynx. A small branch communicates with the recurrent laryngeal nerve.
The branches to the mucous membrane are distributed, some in front to the
epiglottis, the base of the tongue, and the epiglottidean glands; while others
pass backward, in the aryteno-epiglottidean fold, to supply the mucous mem-
brane surrounding the superior orifice of the larynx, as well as the membrane
which lines the cavity of the larynx as low down as the vocal cord. The fila-
ment which joins with the recurrent laryngeal descends beneath the mucous
membrane on the inner surface of the thyroid cartilage, where the two nerves
become united.
The Inferior or Recurrent Laryngeal Branch of the Vagus (n. laryngeus inferior]
(Figs. 698 and 700). — The inferior or recurrent laryngeal branch, so called from
its reflected course, is the motor nerve of the larynx. It arises on the right side,
in front of the subclavian artery; winds from before backward around that vessel,
and ascends obliquely to the side of the trachea, behind the common carotid artery
and behind or in front of the inferior thyroid artery. On the left side it arises in
front of the arch of the aorta, and winds from before backward around the aorta
at the point where the remains of the ductus arteriosus are connected with it, and
then ascends to the side of the trachea. The nerve on each side ascends in the
groove between the trachea and oesophagus, and, passing under the lower border
of the Inferior constrictor muscle, enters the larynx behind the articulation of
the inferior cornu of the thyroid cartilage with the cricoid, being distributed to all
the muscles of the larynx except the Crico-thyroid. It communicates with the
superior laryngeal nerve and gives off a few filaments to the mucous membrane
of the lower part of the larynx.
The recurrent laryngeal, as it winds around the subclavian artery and aorta,
gives off several cardiac filaments, which unite with the cardiac branches from
the vagus and sympathetic. As it ascends in the neck it gives off oesophageal
branches, more numerous on the left than on the right side, which supply the
mucous membrane and muscular coat of the oesophagus; tracheal branches to
the mucous membrane and muscular fibres of the trachea; and some pharyngeal
filaments to the Inferior constrictor of the pharynx.
1072 THE NERVE SYSTEM
The Cervical Cardiac Branches (rami cardiaci superiores). — The cervical cardiac
branches, two or three in number, arise from the vagus, at the upper and lower
part of the neck.
The Superior Branches are small, and communicate with the cardiac branches
of the sympathetic. They can be traced to the great or deep cardiac plexus.
The Inferior Branches, one on each side, arise at the lower part of the neck,
just above the first rib. On the right side this branch passes ventrad or by the
side of the arteria innominata, and communicates with one of the cardiac nerves
proceeding to the great or deep cardiac plexus. On the left side it passes ventrad
of the arch of the aorta and joins the superficial cardiac plexus.
The Thoracic Cardiac Branches (rami cardiaci inferiores). — The thoracic cardiac
branches, on the right side, arise from the trunk of the vagus as it lies by the side
of the trachea, and from its recurrent laryngeal branch, but on the left side from
the recurrent nerve only; passing inward, they terminate in the deep cardiac plexus.
The Ventral Pulmonary Branches. — The ventral pulmonary branches, two or three
in number, and of small size, are distributed on the ventral 'aspect of the root of
the lungs. They join with filaments from the sympathetic, and form the ventral
pulmonary plexus (plexus pulmonalis anterior).
The Dorsal Pulmonary Branches. — The dorsal pulmonary branches, more numer-
ous and larger than the ventral, are distributed on the dorsal aspect of the
root of the lung; they are joined by filaments from the third and fourth (some-
times also from the first and second) thoracic ganglia of the sympathetic,
and form the dorsal pulmonary plexus (plexus pulmonalis posterior). Branches
from both plexuses accompany the ramification of the air-tubes through the sub-
stance of the lungs (rami bronchioles anteriores and rami bronchioles posterior es}.
The (Esophageal Branches (rami oesophagei). — The cesophageal branches are
given off from the vagus both above and below the pulmonary branches. The
lower are more numerous and larger than the upper. They form, together
with branches from the opposite nerve, the oesophageal plexus. From this plexus
branches are distributed to the back of the pericardium.
The Gastric Branches (rami gastrici) (Fig. 698). — The gastric branches are the
terminal filaments of the vagus nerve. The nerve on the right side is distri-
buted to the posterior surface of the stomach. The right vagus sends branches
to the cceliac plexus (rami coeliaci), to the splenic plexus (rami lienales), and to
the renal plexus (rami renales). The nerve on the left side is distributed over the
anterior surface of the stomach, some filaments (rami hepatica) passing across the
great cul-de-sac, and others along the lesser curvature. They unite with branches
of the right nerve and with the sympathetic, some filaments passing through the
lesser omentum to the hepatic plexus.
Surgical Anatomy. — The laryngeal nerves are of considerable importance in considering
some of the morbid conditions of the larynx. When the peripheral terminations of the superior
laryngeal nerve are irritated by some foreign body passing over them, reflex spasm of the glottis
is the result. When the trunk of the same nerve is pressed upon by, for instance, a goitre or
an aneurism of the upper part of the carotid, we have a peculiar dry, brassy cough. When the
nerve is paralyzed, we have anaesthesia of the mucous membrane of the larynx, so that foreign
bodies can readily enter the cavity, and, in consequence of its supplying the crico-thyroid muscle,
the vocal cords cannot be made tense, and the voice is deep and hoarse. Paralysis of the supe-
rior laryngeal nerves may be the result of bulbar paralysis, may be a sequel to diphtheria, when
both nerves are usually involved, or it may, though less commonly, be caused by the pressure
of tumors or aneurisms, when the paralysis is generally unilateral. Irritation of the inferior
laryngeal nerves produces spasm of the muscles of the larynx. When both the recurrent
nerves are paralyzed, the vocal cords are motionless in the so-called cadaveric position — that
is to say, in the position in which they are found in ordinary tranquil respiration — neither closed
as in phonation, nor open as in deep inspiratory effort. When one recurrent nerve is paralyzed,
the cord of the same side is motionless, while the opposite cord crosses the middle line to accom-
modate itself to the affected one; hence phonation is present, but the voice is altered and weak
in timbre. The recurrent laryngeal nerves may be paralyzed in bulbar paralysis or after diph-
THE ELEVENTH OR ACCESSORY NERVE 1073
tlieria, when the paralysis usually affects both sides; or they may be affected by the pressure
of aneurisms of the aorta, innominate or subclavian arteries; by mediastinal tumors; by bron-
chocele; or by cancer of the upper part of the oesophagus, when the paralysis is often unilat-
eral. The nerve may be accidentally divided during the operation for goitre.
It is a well-recognized fact that disease or injury of the vagus may induce serious symptoms.
Bruising may cause such symptoms; so may injury of the nerve by a stab, a bullet, or during
surgical operations. Either accidental ligation or crushing with clamp forceps is particularly
dangerous. Michaux accidentally ligated the vagus, and the patient became comatose and
ceased to breathe, but was restored on removing the ligature. Tillmanns, while removing a
cancer, accidentally caught and crushed a portion of the nerve in a clamp, and both pulse and
respiration ceased. The clamp was removed, the patient was restored with difficulty, and the
nerve was sutured. Recovery followed. It thus becomes evident that division of the vagus on
one side is not, as was so long taught, a necessarily fatal accident; in fact, it is sometimes under-
taken deliberately in removing tumors adherent to the nerve. Division of a nerve which has
been long compressed is probably not so dangerous as division of a healthy nerve, as in the former
case the opposite vagus has probably assumed some of its colleague's duties. A number of cases
of deliberate division have been reported. Twenty-three cases are referred to in the system df
surgery by von Bergmann and Mikulicz, and twelve of them died, but in none of the deaths was
the removal of the vagus the apparent cause of the fatality. The editor of this American edition
of "Gray" has seen three cases: One was operated upon by Dr. W. Joseph Hearn, one by Dr.
Melvin Franklin, and one by the editor. All three recovered, and not one presented any
serious disturbance, although each had hoarseness and weakness of voice.
One would assume that after division of the vagus below the superior laryngeal nerve and
above the recurrent laryngeal nerve (the region usually attacked) that there would be paralysis
of all the muscles of one side of the larynx, except the crico-thyroid, and widespread aberration
evinced by disturbances of the heart, stomach, and lungs. As a matter of fact, this has not been
the case. It might be and probably would be the case, were a healthy nerve divided; but the
surgeon who deliberately divides the nerve does so during the removal of a tumor which has long
made pressure. In most cases there is no change in the pulse or respiration. In some cases
dysphagia and pneumonia arise, but they may be due to other causes than vagus-nerve injury
(the formidable nature and the duration of the operation — the ligation of vessels of large size —
the age of the subject)
Laryngeal symptoms, to a greater or less degree, are always noted. The difference in the
degree of the palsy is explainable when we recall Exner's statement that the muscles supplied
by the recurrent laryngeal also receive some innervation from the superior laryngeal. In fact,
Mills points out that a portion of the recurrent laryngeal has been resected without completely
paralyzing the muscles supposed to be supplied solely by the recurrent laryngeal. The laryngeal
symptoms result from unilateral laryngeal paralysis, in which there is paralysis of the muscles
which open the glottis. The voice may be lost or may be hoarse. Usually, after a time, this is,
to a great extent, compensated for by the opposite vocal cord, although the voice may always
remain weak, and the patient will tire easily on talking. If both vagi were to be divided death
would ensue.
THE ELEVENTH OR ACCESSORY NERVE (N. ACCESSORIUS)
(Figs. 697 and 698).
The eleventh, accessory, or spinal accessory nerve consists of two parts: one the
accessory part to the vagus, and the other the spinal portion.
The Bulbar or Vagal Accessory Part of the Accessory Nerve (Ramus
Interims).
The bulbar or vagal accessory part is the smaller of the two. It is accessory to
the vagus. Its superficial origin (Fig. 697) is by four or five delicate filaments
from the side of the oblongata, below the roots of the vagus. Its deep origin is
described in detail on page 890. It passes outward to the jugular foramen, where
it interchanges fibres with the spinal portion or becomes united to it for a short
distance; it is also connected, in the foramen, with the upper ganglion of the vagus
by one or two filaments. It then passes through the foramen (Fig. 698), and
becoming again separated from the spinal portion it is continued over the surface
68
1074 THE NERVE SYSTEM
of the ganglion of the trunk of the vagus, being adherent to its surface, and is
distributed principally to the pharyngeal and superior laryngeal branches of the
vagus. Through the pharyngeal branch it probably supplies the muscles of the soft
palate. Some few filaments from it are continued into the trunk of the vagus below
the ganglion, to be distributed with the recurrent laryngeal nerve to supply most
of the laryngeal muscle, and probably also with the cardiac nerves.
The Spinal Portion of the Accessory Nerve (Ramus Externus).
The spinal portion is firm in texture. Its superficial origin (Fig. 697) is by
several filaments or rootlets from the lateral tract of the cord, as low down as
the sixth cervical nerve. Its deep origin (Fig 578) may be traced to the inter-
medio-lateral tract of the gray substance of the cord. The rootlets of origin join and
form a trunk which ascends in the subdural space between the ligamentum den-
ticulatum and the ventral roots of the spinal nerves, enters the skull through the
foramen magnum, and is then directed outward to the jugular foramen, through
which it passes, lying in the same sheath as the vagus, but separated from it by a
fold of the arachnoid. In the jugular foramen it receives one or two filaments
from the vagal accessory portion. At its exit from the jugular foramen it passes
into the neck and becomes the external branch (Figs. 655 and 698). It passes
backward, either in front of or behind the internal jugular vein, and descends
obliquely behind the Digastric and Stylo-hyoid muscles to the upper part of the
Sterno-mastoid muscle. It pierces that muscle, and passes obliquely across the
posterior triangle, to terminate in the deep surface of the Trapezius muscle.
This nerve gives several branches to the Sterno-mastoid muscle during its passage
through it, and joins in its substance with branches from the second cervical, which
supply the muscle. In the posterior triangle it joins with the second and
third cervical nerves, while beneath the Trapezius it forms a sort of plexus with
the third and fourth cervical nerves, and from this plexus fibres are distributed
to the muscle.
Surgical Anatomy. — Division of the external branch of the accessory nerve causes paralysis
of the Sterno-cleido-mastoid and Trapezius muscles; not absolute paralysis, for these muscles
also receive nerves from the cervical plexus. In cases of spasmodic torticollis in which all
palliative treatment has failed division or excision of a portion of the external branch of the
accessory nerve has been suggested by Keen. This may be done either along the anterior or
posterior border of the Sterno-mastoid muscle. The former operation is performed by making
an incision from the apex of the mastoid process, three inches in length, along the anterior border
of the Sterno-mastoid muscle. The anterior border of the muscle is defined and pulled back-
ward, so as to stretch the nerve, which is then to be sought for beneath the Digastric muscle,
about two inches below the apex of the mastoid process. The other operation consists in
making an incision along the posterior border of the muscle, so that the centre of the incision
corresponds to the middle of this border of the muscle. The superficial structures having been
divided and the border of the muscle defined, the nerve is to be sought for as it emerges from
the muscle to cross the occipital triangle. When found, it is to be traced upward through the
muscle, and a portion of it is excised above the point where it gives off its branches to the Sterno-
mastoid. In this operation one of the descending branches of the superficial cervical plexus is
liable to be mistaken for the nerve.
THE TWELFTH OR HYPOGLOSSAL NERVE (N. HYPOGLOSSUS)
(Figs. 701 and 702).
The twelfth or hypoglossal nerve is the motor nerve of the tongue. Its super-
ficial origin is by several filaments, from ten to fifteen in number, from the groove
between the pyramidal and olivary bodies of the oblongata, in a continuous line
with the ventral roots of the spinal nerves. Its deep origin can be traced to a
THE TWELFTH OR HYPOGLOSSAL NERVE
1075
nucleus of gray substance (nucleus hypoglossi) in the floor of the fourth ventricle
described on p. 890.
The filaments of this nerve are collected into two bundles, which perforate the
dura separately, opposite the anterior condyloid foramen, and unite together
after their passage through it. In those cases in which the anterior condyloid
To Lingual Nerve
To Qenio-hyoid
To Thyro-hyoid
'o Anterior Belly of Omo-hj/oid
' To Stemo-hyoid
'To Sterna-thyroid
To Posterior Belly of Omo-hyoid
FIG. 701. — Plan of the hypoglossal nerve.
or hypoglossal foramen in the occipital bone is double, these two portions of the
nerve are separated by the small piece of bone which divides the foramen. The
nerve descends almost vertically to a point corresponding with the angle of the
jaw. It is at first deeply seated beneath the internal carotid artery and internal
jugular vein, and is intimately connected with the vagus nerve (Fig. 702); it then
passes forward between the vein and artery, and lower down in the neck becomes
superficial below the Digastric muscle. The nerve then loops around the occipital
artery, and crosses the external carotid and its lingual branch below the tendon
of the Digastric muscle. It passes beneath the tendon of the Digastric, the Stylo-
hyoid, and the Mylo-hyoid muscles, lying between the last-named muscle and the
Hyo-glossus (Fig. 702), and communicates at the anterior border of the Hyo-
glossus with the lingual nerve (Fig. 701); it is then continued forward in the fibres
of the Genio-hyoglossus muscle as far as the tip of the tongue, distributing branches
to its muscular substance.
Branches of Communication (Fig. 701). — The branches of communication
are with the
Vagus.
Sympathetic.
First and Second Cervical Nerves.
Lingual (gustatory).
1076
THE NERVE SYSTEM
The first mentioned takes place close to the exit of the nerve from the skull,
numerous filaments passing between the hypoglossal and the ganglion of the trunk
of the vagus through the mass of connective tissue which here unites the two
nerves. It also communicates with the pharyngeal plexus by a minute filament
as it winds around the occipital artery.
The communication with the sympathetic takes place opposite the atlas vertebra
by branches derived from the superior cervical ganglion, and in the same situa-
tion the nerve is joined by filaments derived from the loop connecting the first
two cervical nerves.
The communication with the lingual nerve takes place near the anterior border
of the Hyo-glossus muscle by numerous filaments which ascend upon it.
Hypoglossal nerve.
Vagus nerve.
Gloksopharyngeal nerve
FIG. 702. — Hypoglossal nerve, cervical plexus, and their branches.
Branches of Distribution (Fig. 701). — The branches of distribution are — the
Dural. Thyro-hyoid.
Descendens hypoglossi. Muscular.
Dural Branches (Fig. 701). — As the hypoglossal nerve passes through the
anterior condyloid foramen it gives off, according to Luschka, several filaments to
the dura in the posterior fossa of the base of the skull; these filaments are probably
derived from a branch which passes from the first cervical nerve to the hypo-glossal
nerve.
The Descendens Hypoglossi (ramus descendens) (Figs. 701 and 702).— The
descendens hypoglossi, long called the descendens noni, is a long slender branch,
THE SYMPA THETIC NER VE SYSTEM 1077
which quits the hypo-glossal where it turns around the occipital artery. It con-
sists mainly of fibres which pass to the hypo-glossal from the first and 'second
cervical nerves in the above-mentioned communication. It descends in front of
or within the sheath of the common carotid artery, giving off a branch to the
anterior belly of the Omo-hyoid, and then joins the communicating branches
from the second and third cervical nerves, just below the middle of the neck, to
form a loop, the ansa hypo-glossi. From the convexity of this loop branches pass
to supply the Sterno-hyoid, Sterno-thyroid, and the posterior belly of the Omo-
hyoid. According to Arnold, another filament descends in front of the vessels into
the chest, and joins the cardiac and phrenic nerves.
The Thyro-hyoid Branch (ramus thyreohyoideus) (Fig. 701). — The thyro-hyoid
is a small branch arising from the hypoglossal near the posterior border of the
Hyo-glossus; it passes obliquely across the great cornu of the hyoid bone and
supplies the Thyro-hyoid muscle.
The Muscular Branches (Fig. 701). — The muscular branches are distributed to
the Stylo-glossus, Hyo-glossus, Genio-hyoid, and Genio-hyo-glossus muscles. At
the under surface of the tongue numerous slender branches (rami linguales) pass
upward into the substance of the organ to supply its intrinsic muscles.
Surgical Anatomy. — A wound in the submaxillary region may injure the hypoglossal nerve
and result in motor paralysis of the corresponding half of the tongue. The hypo-glossal nerve is
an important guide in the operation of ligation of the lingual artery (see page 606). It runs for-
ward on the Hyo-glossus muscle just above the great cornu of the hyoid bone, and forms the
upper boundary of the triangular space in which the artery is to be sought for by cutting through
the fibres of the Hyo-glossus muscle.
THE SYMPATHETIC NERVE SYSTEM (SYMPATHICUS) (Fig. 703).
The sympathetic nerve system consists of (1) a series of ganglia (ganglia trunci
sympathici) connected together by a great ganglionic cord, the gangliated cord
(truncus sympathicus] , extending from the base of the skull to the coccyx, one
gangliated cord on each side of the middle line of the body, partly in front and
partly on each side of the vertebral column ; (2) of three great gangliated plexuses
(plexus sympathici) or aggregations of nerves and ganglia, situated in front of
the spine in the thoracic, abdominal, and pelvic cavities respectively; (3) of smaller
or terminal ganglia, situated in relation with the abdominal viscera; and (4) of
numerous nerve-fibres. These latter are of two kinds: communicating, by which
the ganglia communicate with each other and with the cerebro-spinal nerves; and
distributory, supplying the internal viscera and the coats of the blood-vessels.
Each gangliated cord may be traced upward from the base of the skull into the
cranial cavity by an ascending branch, which passes through. the carotid canal,
forms a plexus on the internal carotid artery and in the cavernous sinus (Fig. 707),
and communicates with certain cranial nerves (p. 1084). According to some
anatomists, the two cords are joined, at their cephalic extremities, by these ascend-
ing branches communicating in a small ganglion, the ganglion of Ribes, situated
upon the anterior communicating artery. Upon the gangliated cord are ganglia
distinguished as cervical, thoracic, lumbar, and sacral, and except in the neck they
correspond pretty nearly in number to the vertebrae against which they lie. They
may be thus arranged:
Cervical portion 3 pairs of ganglia.
Thoracic " 12 "
Lumbar " 4 "
Sacral " . . 4 or 5 "
1078
THE NER VE SYSTEM
ACCESSORY
CERVICAL
PLEXUS
SUPERIOR CERVICAL
GANGLION OF SYM-
PATHETIC
MIDDLE CERVI-
CAL GANGLION
INFERIOR CERVI-
CAL GANGLION
In the neck they are situated in front of the transverse processes of the vertebrae;
in the thoracic region, in front of the heads of the ribs; in the lumbar region, on the
sides of the bodies of the vertebra?; and in the sacral region, in front of the sacrum.
As the two cords pass into the
pelvis they converge and unite
together in a single ganglion, the
coccygeal ganglion or ganglion
impar (ganglion coccygeum im-
par) placed in front of the coccyx.
Each ganglion may be regarded
as a distinct centre, and, in ad-
dition to its branches of distri-
bution, possesses also branches
of communication which com-
municate with other ganglia and
with the cerebro-spinal nerves.
The branches of communication
between the ganglia (Figs. 704
and 705) are composed of gray
nerve-fibres (gray rami commu-
nicantes) and white nerve-fibres
(white rami communicantes) , the
latter being continuous with
those fibres of the spinal nerves
which pass to the ganglia.
The three great gangliated
plexuses (collateral ganglia) are
situated in front of the spine in
the thoracic, abdominal, and
pelvic regions, and are named,
respectively, the cardiac, the solar
or epigastric, and the hypogastric
plexus. They consist of collec-
tions of nerves and ganglia, the
nerves being derived from the
gangliated cords and from the
cerebro-spinal nerves. They dis-
tribute branches to the viscera.
Smaller or Terminal ganglia are
also found lying amidst the
nerves, some of them of micro-
scopic size, in certain viscera —
as, for instance, in the heart, the
stomach, and the uterus. They
serve as additional centres for
the origin of nerve-fibres. There
are numerous special ganglia
connected with the cranial nerves.
FIG. 703. — Anterior surface of the spinal cord, showing the These ganglia have been de-
spinal nerves and their connections with the sympathetic trunk ., , . . ,. /
on one side. (Testut.) scribed in a previous section (see
ophthalmic ganglion, otic gan-
glion, spheno-palatine ganglion, and submaxillary ganglion).
The branches of distribution derived from the gangliated cords, from the pre-
vertebral plexuses, and also from the smaller ganglia, are principally destined
LUMBAR GANGLIA
COCCYGEAL
PLEXUS
THE S YMPA THETIC NER VE S YSTEM \ 079
for the blood-vessels and thoracic and abdominal viscera, supplying the involun-
tary muscular fibre of the coats of the vessels and the hollow viscera, and the
secreting cells, as well as the muscular coats of the vessels in the glandular viscera.
Structure of the Sympathetic System. — The sympathetic system is not, as was
so long taught, an independent system. It receives fibres from the cerebro-spinal
svstem and arranges them for distribution to the splanchnic blood-vessels and
the viscera. It receives fibres from the viscera and transmits them to the cerebro-
spinal system, and it transmits fibres by way of the spinal nerves to unstriped
muscles, to vessels, and to glands. It is simply an arrangement of spinal
nerves to permit of the re-arrangement and transmission of impulses. In order
to effect this, the spinal nerves are connected with a series of ganglia, which possess
a certain power of government or automatic action. In the sympathetic system
amyelinic fibres predominate. The individual nerve-fibres are smaller in diam-
eter than those of the cerebro-spinal system, and the fibres are interrupted by
nerve-cells contained in a ganglia chain, known as the gangliated cord, and are
also sometimes interrupted in gangliated plexuses and in terminal ganglia. The
sympathetic nerves have a notable disposition to form plexuses. It is important
to note that not all of the visceral branches of the spinal nerves join the gangli-
ated cord — for instance, the visceral branches of the third and fourth sacral do
not. The majority, but not all, of the sympathetic fibres are amyelinic (fibres of
Remak}, but in the adult true amyelinic fibres are found only in the sympathetic
system. These fibres are of smaller diameter than spinal nerve-fibres, and are
prolongations of axones of sympathetic ganglia cells. Each fibre is surrounded
by connective-tissue structure which resembles the neurilemma, which contains
numerous nuclei, and which is a prolongation of the capsule of a sympathetic cell
capsule.
A sympathetic nerve consists of numerous amyelinic and some myelinic fibres.
The connective tissue which separates the nerve-bundles carries blood-vessels and
nervi nervorum, but no lymph vessels.
The sympathetic ganglia contain multipolar cells which are smaller. 4han those
of the spinal ganglia. Each cell contains two nuclei, and is surrounded by a
delicate capsule of connective tissue. The cell gives off one axone and several
short dendrites. The axone is amyelinic when it begins and may remain so or
may become myelinic. Fibres which take origin from sympathetic axones,
the commissural fibre, may pass to an adjacent ganglion cell, may pass toward the
centre, central fibre or gray ramus communicans, or may pass toward the periphery,
peripheral fibre, and reach certain glands, or to unstriped muscle of blood-vessels,
intestines, iris, etc. The fibres passing to glands are called secretor fibres.
The dendrites of a sympathetic ganglion cell form arborizations about other
ganglion cells. The sympathetic ganglia contains fibres as well as cells. Some
of the fibres are myelinic and some are amyelinic, the latter taking origin from the
sympathetic ganglion cells, the former being motor and sensor cerebro-spinal
fibres which have reached the sympathetic by the rami communicantes.1
The myelinic fibres, the white rami communicantes or the visceral branches of the
spinal nerves (Figs. 704 and 705), originate from the ventral divisions of certain
accessory nerves. Two groups of them can be recognized, one group coming from
the nerves from the first or second thoracic to the second or third lumbar nerves;
another group from the second or third lumbar to the third or fourth sacral. The
visceral branches of the third and fourth sacral do not join the gangliated cord;
the other visceral branches do join it. The fibres of the visceral branches of the
spinal nerves are derived from both the ventral and the dorsal nerve-roots, but
more largely from the ventral than from the dorsal. The visceral fibres of the
ventral roots are axones of nerve-cells of the spinal cord, and by way of the white
1 Histology and Microscopic Anatomy, by Szymonowicz. Translated and edited by John Bruce MacCallum.
1080
THE NERVE SYSTEM
rami enter into the sympathetic ganglia. Some of them end and form networks
about the ganglia cells. Others pass up or down and end in an adjacent ganglion.
Others pass through a ganglion of the gangliated cord and end in a peripheral
ganglion with amyelinic fibres, which take origin from ganglia of the gangliated
cord. The fibres of the white ramus which pass through the ganglion and go to
the periphery are known as the splanchnic efferent fibres, and constitute the secretor
fibres of the splanchnic glands and the motor fibres of the muscular tissue of
splanchnic blood-vessels and viscera. The visceral fibres of the dorsal nerve-
roots aid in the formation of the white rami and arise as axones of nerve-cells in
the spinal ganglia on the dorsal roots; they then pass through the ganglia of the
sympathetic cord, but do not terminate in them, and leave the ganglion directly to
pass through a peripheral ganglion to be distributed to the periphery, or ascend,
or descend to an adjacent ganglion and pass through this to a collateral ganglion,
and thence to the periphery. They constitute the splanchnic afferent fibres, the
sensor fibres of the viscera.
ACCOMPANYING DORSAL
ROOT TO DURA ^ DORSAL SPINAL
NERVE ROOT
/ERTEBR/t LIGAMENTS,
INAL VESSELS A DURA
SOMATIC VASOMOTOR,
PILOMOTOR, SECRETORY
FROM RAMUS' COMMUN.
TO VERTEBR/E AND
INTERCOSTAL AND
LUMBAR VESSELS.
.YMPATHETIC TRUNK
RAMI EFFERENTES
-SYMPATHETIC GANGLION
MEDufLATEO FIBRES PASSING THROUGH THE
GANGLION TO PREVERTEBRAL PLEXUSES
OR DIRECTLY TO VISCERA.
^SYMPATHETIC TRUNK
[•FROM LOWER GANGLIA
fTO LOWER GANGLIA
FIG. 704.— Plan of a vertebral ganglion of the sympathetic cord and its connections. Myelinic fibres consti-
tuting white ramus communicans, represented by continuous lines, amyelinic fibres, constituting gray ramus
communicans, by interrupted lines. For references to letters see text. (W. Keiller.)
The amyelinic fibres take origin from the cells of the sympathetic ganglia and
are axones of these cells. Some help to form the commissure, which joins a
ganglion to adjacent ganglia and end as networks about the cells of an adjacent
ganglion. Others run to the periphery and help to form the splanchnic efferent
branches. Some pass from the ganglia to the spinal nerve-roots and to the
ventral and dorsal divisions of the nerves. The latter are the gray rami communi-
cantes (Fig. 705), largely composed of amyelinic but containing some myelinic
fibres. They give branches to the somatic part of the nerves but not the visceral,
and furnish secretor fibres and fibres to unstriated muscle and minute branches
to the membranes which enwrap the nerve-roots. The commissures of the
gangliated cord are composed of white and gray fibres. The former consist of
both splanchnic efferent and splanchnic afferent fibres. The latter are axones
from sympathetic ganglion cells, and some of these are truly commissural, but
THE CERVICAL PORTION OF THE GANGLIA TED CORD 1081
others pass up or down the cord and through a ganglion and become branches
which go to the periphery.
From the above it becomes evident that the peripheral branches of the sym-
pathetic contain white fibres, which are composed of splanchnic efferent and
splanchnic afferent branches and also contain splanchnic efferent gray fibres.
These connections will be better understood by examining the plan drawn out
in Fig. 704. There a represents a myelinic nerve-fibre from a ventral nerve-
root, passing by a white ramus communicans through the ganglion directly con-
nected with that spinal nerve to a ganglion higher up, where it will form an
arborization round a nerve-cell, like e; b, a myelinic nerve-fibre forming an
arborization round a cell of the ganglion of its own segment; c, a fibre passing
through the ganglion without interruption and leaving it by one of its efferent
branches to a prevertebral plexus or directly to some viscus; d, a fibre passing
through the ganglion to some lower ganglion, there to end round some nerve-cell,
or pass out through an efferent ramus; e, a myelinic nerve from a lower ganglion,
behaving as a.
The dotted lines are amyelinic nerves. The fibre, /, arises as the axis-cylinder
process of a ganglion cell, and passes by a gray ramus communicans along the
sheath of the posterior nerve-root to the spinal meninges; g passes by the posterior
division to supply sympathetic fibres to its area of distribution; h enters the
anterior division and is similarly distributed; k joins the spinal recurrent branch
to supply the interior of the vertebral canal, and / passes for a little way along the
gray ramus communicans, but leaves it to be distributed to the sides of the verte-
brae and intercostal or lumbar vessels. Gray fibres to the prevertebral plexuses,
vessels, or viscera, are represented by m, m; and n, n are amyelinic fibres joining
neighboring ganglia. In addition to these, sensor fibres from the ganglia of the
posterior spinal nerve-roots pass through the sympathetic ganglia to viscera without
interruption.
THE GANGLIATED CORD (TRUNCUS SYMPATHICUS).
The Cervical Portion (Pars Cervicalis) of the Gangliated Cord.
The cervical portion of the gangliated cord is to be regarded as a prolongation
upward of the primitive sympathetic along the great vessels of the neck
(Cunningham). It is not connected to the cervical spinal nerves by white rami
communicantes. It obtains its spinal fibres from the upper thoracic nerves. These
fibres ascend in the commissure of the gangliated cord and join the cells of the
cervical ganglia. From the cervical ganglia come fibres to the unstriped muscle
(veins and arteries of the head, neck, and limbs, and to the skin of the head and
neck, secretor fibres to the salivary glands and fibres to the heart). The fibres
to the vessels are called vasomotor nerves, and the fibres to the heart are called
cardio-motor nerves. In the neck the gangliated cord is situated behind the carotid
vessels and upon the muscles in front of the vertebrae, and runs from the root
of the neck to the base of the skull, being continuous below with the thoracic
gangliated cord and ending above in the carotid plexus. There are usually three
ganglia on each side, each of which is distinguished, according to its position, as the
superior, middle, and inferior cervical ganglion.
The Superior Cervical Ganglion (ganglion cervicale superius) (Figs. 705 and
706). — The superior cervical ganglion, the largest of the three, is about three-
quarters of an inch in length. It is placed opposite the second and third cervical
vertebne. It is of a reddish-gray color, is usually fusiform in shape, is sometimes
broad and flattened, and is occasionally constricted at intervals, so as to give rise to
1082
THE NERVE SYSTEM
the opinion that it consists of the coalescence of several smaller ganglia ; and it is
usually believed that it is formed by the coalescence of the four ganglia correspond-
Superior cervical ganglion.
Middle cervical ganglion.
Inferior cervical ganglion.
Pharyngeal branches.
Cardiac branches.
Deep cardiac plexus.
Superficial cardiac plexus.
Solar plexus.
Aortic plexus.
Hypogastric plexus.
Sacral ganglia.
Ganglion impar.
FIG. 705. — The sympathetic nerve system.
THE CERVICAL PORTION OF THE GANGLIATED CORD 1Q83
ing to the four upper cervical nerves. It is in relation, in front, with the sheath
of the internal carotid artery and internal jugular vein; behind, it lies on the
Ilectus capitis anticus major muscle. It is connected to the middle cervical gan-
glion by the commissure of the gangliated cord.
Branches. — The branches of the superior cervical ganglion are central and
peripheral.
Central or Communicating Branches. — 1. Gray rami communicantes arise in the
ganglion and pass to the first, second, third, and fourth cervical nerves. 2.
Branches are given oi¥ to certain cranial nerves in the neck (Fig. 706). What is
known as the jugular nerve (n. jugularis) passes to the ganglion on the trunk
of the vagus, a branch from the ganglion passes to the ganglia on the root of
the vagus and to the petrosal ganglion of the glosso-pharyngeal, and a branch
goes to the hypo-glossal.
Peripheral Branches. — These branches may be divided into superior, internal,
and anterior.
The Superior Branch of the Superior Cervical Ganglion or the Internal Carotid
Branch (n. caroticus internus) (Fig. 706) appears to be a direct prolongation of the
ganglion. It is soft in texture and of a reddish color. It ascends by the side of
the internal carotid artery, and, entering the carotid canal in the temporal bone,
divides into two branches, which lie, one on the outer, and the other on the inner,
side of that vessel.
The outer branch, the larger of the two, distributes filaments to the internal
carotid artery and forms the internal carotid plexus.
The inner branch also distributes filaments to the internal carotid, and, continu-
ing onward, forms the cavernous plexus.
THE INTERNAL CAROTID PLEXUS (plexus caroticus internus} (Figs. 705 and
706). — The carotid plexus is situated on the outer side of the internal carotid
artery. Filaments from this plexus occasionally form a small gangliform swelling
on the under surface of the artery, which is called the carotid ganglion. The internal
carotid plexus communicates with the Gasserian ganglion, with the abducent nerve,
and the spheno-palatine ganglion, and distributes filaments to the wall of the
carotid artery and to the dura (Valentin), while in the carotid canal it com-
municates with Jacobson's nerve, which is the tympanic branch of the glosso-
pharyngeal.
The communicating branches to the abducent nerve consist of one or two
filaments which join that nerve as it lies upon the outer side of the internal
carotid. Other filaments are also connected with the Gasserian ganglion. The
communication with the spheno-palatine ganglion is effected by a branch, the
large deep petrosal nerve (Fig. 694), which is given off from the plexus on the
outer side of the artery, and which passes through the cartilage filling up the
foramen lacerum medium, and joins the large superficial petrosal from the facial
to form the Vidian nerve (Figs. 689 and 694). The Vidian nerve then proceeds
along the pterygoid or Vidian canal to the spheno-palatine ganglion. The com-
munication with Jacobson's nerve is effected by two branches, one of which
is called the deep petrosal nerve, and the other the carotico-tympanic nerve; the
latter may consist of two or three delicate filaments.
THE CAVERNOUS PLEXUS (plexus cavernosus) (Fig. 706). — The cavernous
plexus is situated below and internal to that part of the internal carotid wrhich
is placed by the side of the sella cavernous sinus, and is formed chiefly by the
internal division of the ascending branch from the superior cervical ganglion.
It communicates with the oculomotor, the trochlear, the ophthalmic division of
the trigeminal, and the abducent nerves, and with the ophthalmic ganglion, and
distributes filaments to the wall of the internal carotid and to the hypophysis.
The branch of communication with the oculomotor nerve joins it at its point of
1084
THE NER VE SYSTEM
division; the branch to the trochlear nerve joins it as it lies on the outer wall of
the cavernous sinus ; other filaments are connected with the under surface of the
trunk of the ophthalmic nerve; and a second filament of communication joins the
abducent nerve.
The filament of connection with the ophthalmic ganglion (Fig. 684) arises from
the anterior part of the cavernous plexus; it accompanies the nasal nerve or con-
tinues forward as a separate branch.
Terminal Branches of the Carotid and Cavernous Plexuses.— The terminal
filaments from the carotid and cavernous plexuses are prolonged along the internal
carotid, forming plexuses which entwine around the cerebral and ophthalmic
arteries; along the former vessels they may be traced on to the pia; along the
latter, into the orbit, where they accompany each of the subdivisions of the vessel,
a separate plexus passing, with the arteria centralis retinae, into the interior of
EXTERNAL
RECTUS
MUSCLE
OPHTHALMIC
GANGLION
SENSOR ROOT
OF OPHTHALMIC
GANGLION
OPHTHALMIC
GASSERIAN
GANGLION
(turned forward)
GREAT DEEP
PETROSAL
TEMPORO-
MAXILLARY
ARTICULATION
SMALL DEEP
PETROSAL
MOTOR ROOT OF
OPHTHALMIC GANGLION
UPPER BRANCH
OF OCULO-MOTOR
LOWER BRANCH
OF OCULO-MOTOR
SYMPATHETIC ROOT OF
OPHTHALMIC GANGLION
OCULO-MOTOR NERVE
OPHTHALMIC
ARTERY
HYPOPHYSIS
CAVERNOUS
PLEXUS
ABDUCENT NERVE
COMMUNICATING
BRANCH TO ABDUCENT NERVE
INTERNAL
CAROTID PLEXUS
INTERNAL
.CAROTID BRANCH
OF SUPERIOR
CERVICAL GANGLION
INFERIOR INTERNAL^ jS||f— ^SUPERIOR
COROTICOTYMPANIC CAROTID » CERVICAL
ARTERY GANGLION
FIG. 706.— The cephalic portion of the sympathetic nerve system, seen obliquely from
above and behind. (Toldt.)
the eyeball. The filaments prolonged on to the anterior communicating artery
form a small ganglion, the ganglion of Ribes,1 which serves, as mentioned above,
to connect the sympathetic nerves of the right and left sides.
The so-called Inferior or Descending Branch of the Superior Cervical Ganglion
communicates with the middle cervical ganglion. It is the commissure of the
gangliated cord.
The Internal Branches of the Superior Cervical Ganglion are three in number — the
pharyngeal, laryngeal, and superior cardiac nerve.
The pharyngeal branches (rami pkaryngei) (Fig. 705) pass inward to the side of
the pharynx, where they join with branches from the glosso-pharyngeal, vagus,
and external laryngeal nerves to form the pharyngeal plexus.
i The existence of this ganglion is doubted by some observers.— ED. of 15th English edition.
THE CERVICAL PORTION OF THE GANGLIATED CORD 1085
CAVERNOUS PLEXUS
SUP. MAXILLARY NERVE
FIRST
Cf RVICAL
NERVE
The laryngeal branches unite with the superior laryngeal nerve and its branches.
The superior cardiac nerve or the nervus superficialis cordis (n. cardiacus supe-
rior) (Fig. 705) arises by two or more branches from the superior cervical gan-
glion, and occasionally receives a filament from the cord of communication
between the first and second cervical ganglia. It runs down the neck behind the
common carotid artery, lying upon the Longus colli muscle, and crosses in front of
the inferior thyroid artery and recurrent laryngeal nerve. The right superior cardiac
nerve, at the root of the neck, passes either in front of or behind the subclavian
artery, and along the arteria innominata, to the back part of the arch of the aorta,
where it joins the deep cardiac plexus. This nerve, in its course, is connected with
other branches of the sympathetic; about the middle of the neck it receives fila-
ments from the external laryngeal nerve; lower down it obtains one or two twigs
from the vagus, and as it enters
the thorax it is joined by a fila-
ment from the recurrent laryn-
geal. Filaments from this nerve
communicate with the thyroid
branches from the middle cer-
vical ganglion. The left superior
cardiac nerve, in the chest, runs
by the side of the left common,
carotid artery and in front of the
arch of the aorta to the superficial
cardiac plexus, but occasionally
it passes behind the aorta and
terminates in the deep cardiac
plexus.
The Anterior Branches of the
Superior Cervical Ganglion (nn.
carotid externi) (Fig. 707) ramify
upon the external carotid artery
and its branches, forming around
each a delicate plexus, on the
nerves composing which small
ganglia are occasionally found.
The plexuses accompanying
some of these arteries have
important communications with
other nerves. That surrounding
the external carotid artery (plexus
caroticus externus] is connected
with the branch of the facial
nerve to the Stylohyoid muscle; ^ Nl
J . * ' JIG. 707. — Diagram of the cervical sympathetic cord. (Testut.)
that surrounding the facial artery
communicates with the submaxillary ganglion by one or two filaments; and that
accompanying the medidural artery sends offsets which pass to the otic ganglion
and to the geniculate ganglion of the facial nerve and constitute the external super-
ficial petrosal nerve (Fig. 694).
The Middle Cervical or Thyroid Ganglion (ganglion cervical medium) (Figs.
705 and 707). — The middle cervical or thyroid ganglion is the smallest of the three
cervical ganglia, and is occasionally altogether wanting. It varies somewhat in
position, but in most individuals is placed opposite the sixth cervical vertebra,
usually upon, or close to, the inferior thyroid artery; hence the name, thyroid
ganglion, assigned to it by Haller. It is probably formed by the coalescence of
two ganglia corresponding to the fifth and sixth cervical nerves.
LOWER CERVICAL
GANGLION
INFERIOR CER
GANGLIO
1086 THE NERVE SYSTEM
It communicates above with the superior cervical ganglion and below with
the inferior cervical ganglion by means of the commissure of the gangliated cord.
The Central Communicating Branches. — The central communicating branches
are: 1. Gray rami communicantes passing from the ganglion to the anterior
divisions of the fifth and sixth cervical nerves. 2. The subclavian loop or the
ansa of Vieussens (ansa subclavia) (Fig. 708) arises from the ganglion, passes down
over the front and under the subclavian artery and runs back to join the inferior
cervical ganglion. It gives branches to the artery. In some cases this nerve takes
origin from the sympathetic trunk below the ganglion.
The Peripheral Branches. — The peripheral branches are the thyroid and the
middle cardiac nerve.
The Thyroid Branches are small filaments which accompany the inferior thyroid
artery to the thyroid gland, forming the inferior thyroid plexus (plexus thyreoideus
inferior) ; they communicate, on the artery, with the superior cardiac nerve, and,
in the gland, with branches from the recurrent and external laryngeal nerves.
The Middle or Great Cardiac Nerve (n. cardiacus medius) (Fig. 705), the largest
of the three cardiac nerves, arises from the
middle cervical ganglion or from the cord
between the middle and inferior ganglia. On
the right side it descends behind the common
carotid artery, and at the root of the neck
passes either in front of or behind the sub-
clavian artery; it then descends on the
trachea, receives a few filaments from the
recurrent laryngeal nerve, and joins the right
side of the deep cardiac plexus. In the neck
it communicates with the superior cardiac
FIG. 708. — The subclavian loop passing from the „„,] rpmrrpnt larvno-pnl nprvps On thp Ipff
middle to the inferior cervical ganglia. nl l^ryngea .rVCS.
side the middle cardiac nerve enters the chest
between the left carotid and subclavian arteries, and joins the left side of the deep
cardiac plexus. If the middle cervical ganglion is absent, the above-named
branches arise from the gangliated cord.
The Inferior Cervical Ganglion (ganglion cervicale inferius) (Figs. 705 and 707) .
—The inferior cervical ganglion is situated between the base of the transverse
process of the last cervical vertebra and the neck of the first rib on the inner side
of the superior intercostal artery. Its form is irregular; it is larger in size than the
preceding, and is frequently joined to the first thoracic ganglion. It is prob-
ably formed by the coalescence of two ganglia which correspond to the two last
cervical nerves. It joins the middle ganglion above and the first thoracic ganglion
below by means of the commissural cord, and is usually also joined to the middle
ganglion by the subclavian loop.
The Central Communicating Branches. — Its central communicating branches are:
1. Gray rami communicantes passing to the anterior divisions of the seventh and
eighth cervical nerves (Fig. 707). 2. The subclavian loop (Fig. 708), which has
been previously described and which passes under and in front of the subclavian
artery to reach the middle cervical ganglion or the commissural cord.
The Peripheral Branches. — The peripheral branches are: 1. Vascular. The
vertebral plexus (plexus vertebralis) lies upon the vertebral artery and its branches
in the neck and in the cranial cavity, The subclavian plexus (plexus subclavius)
arises from the subclavian loop, which may be regarded as a branch of the inferior
or of the middle ganglion. 2. Cardiac. The inferior or minor cardiac nerve (n.
cardiacus inferior) arises from the inferior cervical or first thoracic ganglion. It
passes down behind the subclavian artery and along the front of the trachea to
join the deep cardiac plexus. It communicates freely behind the subclavian
artery with the recurrent laryngeal and middle cardiac nerves.
THE THORACIC PORTION OF THE GANGLIATED CORD 1Q87
Surgical Anatomy. — The situation of the cervical sympathetic makes wounds of it rare.
Thirteen cases of sympathetic traumatic injury were collected by Seeligmiiller. In ten cases
paralysis existed; in three, irritation. Tumors of the neck may cause irritation or paralysis. In
irritation of the sympathetic the corresponding side of the face becomes pale, the pupil dilates,
the palpebral fissure widens, and the eyeball protrudes. In many cases there is acceleration
of the heart beats. In paraly.ns of the sympathetic the pupil contracts, the palpebral fissure is
narrowed by partial ptosis, the corresponding side of the face reddens, there is an increase in
the flow of tears, and recession of the eyeball.
The surgeon occasionally resects the sympathetic. Jonnesco recommends bilateral removal
of the superior cervical ganglia for glaucoma, and bilateral removal of all the cervical sympa-
thetic ganglia for epilepsy and for exophthalmic goitre.
The Thoracic Portion (Pars Thoracalis) of the Gangliated Cord (Fig. 709).
The thoracic portion of the gangliated cord consists of a series of ganglia
which usually correspond in number to that of the vertebrae, but, from the occa-
sional coalescence of two, their number is uncertain. These ganglia are placed
on each side of the spine, resting against the heads of the ribs, and are covered by
the pleura costalis; the last two ganglia are, however, ventral to the rest, being
placed on the side of the bodies of the eleventh and twelfth thoracic vertebrae. The
ganglia are small in size and of a grayish color. The first ganglion, larger than
the rest, is of an elongated form and is frequently blended with the last cervical
ganglion. They are connected together by cord-like prolongations from their
substance. In the thorax each thoracic spinal nerve, with occasionally the
exception of the first, sends a visceral branch or white ramus communicans to
the thoracic gangliated cord (Fig. 709). As Prof. Cunningham points out, the
white rami "separate into two main streams in relation to the sympathetic cord.
Those of the upper five nerves are, for the most part, directed upward in the
gangliated cord to be distributed through the cervical part of the sympathetic
in the manner already described. The white rami of the lower thoracic nerves
are, for the most part, directed downward in the lower part of the sympathetic
cord and its branches, to be distributed to the abdomen; at the same time some
of their fibres are directly associated with the supply of certain thoracic viscera —
lungs, aorta, oesophagus." The white rami are composed of splanchnic afferent
fibres and somatic and splanchnic efferent fibres.
Central Communicating Branches. — 1. White rami communicantes (see above).
2. Gray rami communicantes arise from each one of the thoracic ganglia, pass back-
ward with the white rami, and enter into the ventral divisions of the thoracic nerves.
Peripheral Branches. — 1. Aortic Branches come off from the first five or six
upper ganglia. They send filaments to the aorta and its branches, to the vertebral
bodies, and to the vertebral ligaments. The aortic branches help to form the
thoracic aortic plexus (plexus aorticus thoracalis). This plexus is completed by
branches from the cardiac plexus.
2. Pulmonary Branches come off from the third and fourth and sometimes from
the first and second ganglia.
3. The Splanchnic Nerves (Figs. 705 and 709). — From the six or seven lower
ganglia and from the commissural cord a number of large white branches arise.
They give filaments to the aorta and unite to form the three splanchnic nerves on
each side. These are named the great, the lesser, and the smallest or renal splanchnic.
The superior or great splanchnic nerve (».. splanchnicus major) is of a white
color, firm in texture, and presents a marked contrast to the ganglionic nerves.
It is formed by branches from the thoracic ganglia between the fifth or sixth
and the ninth or tenth, but the fibres in the higher roots may be traced upward
in the sympathetic cord as far as the first or second thoracic ganglion. These
roots unite to form a large round cord of considerable size. It descends obliquely
1088
THE NER VE SYSTEM
inward in front of the bodies of the vertebrae along the posterior mediastinum,
perforates the crus of the Diaphragm, and terminates in the semilunar ganglion of
the solar plexus (Fig. 709), distributing filaments to the renal and adrenal plexuses.
The middle, lesser, or small splanchnic nerve (n. splanchnicus minor) is formed
by filaments from the tenth and eleventh ganglia, and from the cord between them.
It pierces the Diaphragm with the preceding nerve, and joins the solar plexus
(Fig. 709). It communicates in the chest with the great splanchnic nerve, and
occasionally sends filaments to the renal plexus.
THORACI
RAMI COMMU
INFERIOR CER-
VICAL GANGLION
VISCERAL
BRANCHES
SPLANCHNIC
GANGLION
GREAT
SPLANCHNIC
SMALL
SPLANCHNIC
RIGHT VAGUS
SMALL
SPLANCHNIC
BRANCH OF VAGUS
TO SEMILUNAR GANGLION
CELIAC AXIS
SEMILUNAR GANGLION
SUPERIOR MESENTERIO
ARTERY AND PLEXUS
SOLAR PLEXUS
QUADRATUS
LUMBORUM
RENAL PLEXUS
FIG. 709. — Plan of the right sympathetic cord and splanchnic nerves. (Testut.)
The inferior, smallest, least, or renal splanchnic nerve (n. splanchnicus imus) arises
from the last thoracic ganglion, and, piercing the Diaphragm, terminates in the
renal plexus and lower part of the solar plexus. It occasionally communicates with
the preceding nerve.
A striking analogy appears to exist between the splanchnic and the cardiac
nerves. The cardiac nerves are three in number; they arise from the three cer-
vical ganglia, and are distributed to a large and important organ in the thoracic
PELVIC OR SACRAL PORTION OF GANGLIA TED CORD 1089
cavity. The splanchnic nerves, also three in number, are connected probably
with all the thoracic ganglia, and are distributed to important organs in the
abdominal cavity
The Lumbar Portion (Pars Lumbalis) of the Gangliated Cord (Fig. 705).
The lumbar portion of the gangliated cord is situated in front of the vertebral
column along the inner margin of the Psoas muscle. It consists usually of four
ganglia, but there may be as many as eight, connected together by interganglionic
cords. The ganglia are of small size, of a grayish color, shaped like a barleycorn,
and placed much nearer the median line than the thoracic ganglia. Sometimes
several ganglia are fused together.
It is connected with the thoracic portion by a thin commissure, which passes
back of or through the Diaphragm. It is connected with the sacral portion by
a commissure which is under the common iliac artery.
The upper lumbar ganglia or the upper portion of the gangliated cord receives
white rami communicantes from the first two or three lumbar spinal nerves.
Central Communicating Branches. — Gray rami communicantes pass irregularly from
the gangliated cord to the ventral divisions of the lumbar spinal nerves, the gray
rami accompanying the white rami.
From the situation of the lumbar ganglia these branches are longer than in the
other regions. They are -usually two in number from each ganglion, but their
connection with the spinal nerves is not so uniform as in other regions. They
accompany the lumbar arteries around the sides of the bodies of the vertebrae,
passing beneath the fibrous arches from which some of the fibres of the Psoas
muscle arise.
Peripheral Branches. — Some branches pass inward, in front of the aorta, and
help to form the abdominal aortic plexus (plexus aorticus abdominalis) (Fig. 705)
which plexus is, however, developed chiefly by filaments from the cceliac plexus.
Other branches descend in front of the common iliac arteries, and join over the
promontory of the sacrum, helping to form the hypogastric plexus (plexus hypo-
gastricus) (Fig. 705). Numerous delicate filaments are also distributed to the
bodies of the vertebrae and the ligaments connecting them.
Pelvic or Sacral Portion (Pars Sacralis) of the Gangliated Cord (Fig. 705).
The pelvic portion of the gangliated cord is situated in front of the sacrum
along the inner side of the ventral sacral foramina. It consists of four or five
small ganglia on each side, connected together by interganglionic cords. Below
these cords converge and unite on the front of the coccyx by means of a small
ganglion, the coccygeal ganglion or ganglion impar (ganglion coccygeum impar
(Fig. 705). The commissural cord joins the pelvic portion to the lumbar portion
of the gangliated cord. Like the cervical and the lower lumbar divisions the
sacral portion receives no white rami communicantes.
The visceral branches of the third sacral, and usually of the second and fourth
sacral spinal nerves, are not connected with the ganglionic cord.
Central Communicating Branches. — Gray rami communicantes, which arise in the
sacral ganglia and pass to the anterior divisions of the sacral and coccygeal nerves.
Peripheral Branches. — 1. Visceral branches arise from the upper portion of the
gangliated cord and pass to the pelvic plexus.
2. Parietal branches communicate, on the front of the sacrum, with the corre-
sponding branches from the opposite side; some, from the first two ganglia, pass to
69
1090 THE NERVE SYSTEM
join the pelvic plexus, and others form a plexus which accompanies the middle
sacral artery and sends filaments to the coccygeal gland.
THE GREAT PLEXUSES OF THE SYMPATHETIC SYSTEM.
The great plexuses of the sympathetic are the large aggregations of nerves
and ganglia, previously alluded to, situated in the thoracic, abdominal, and pelvic
cavities respectively. From them are derived the branches which supply the
viscera.
The Cardiac Plexus (Plexus Cardiacus) (Fig. 705).
The cardiac plexus is situated at the base of the heart, and is divided into a
superficial part, which lies in the concavity of the arch of the aorta, and a deep
part, which lies between the trachea and aorta. The two plexuses are, however,
closely connected.
The Great or Deep Cardiac Plexus.— The great or deep cardiac plexus,
the plexus magnus profundus of Scarpa, is situated in front of the trachea at its
bifurcation, above the point of division of the pulmonary artery and behind the
arch of the aorta. It is formed by the cardiac nerves derived from the cervical
ganglia of the sympathetic and the cardiac branches of the recurrent laryngeal
and vagus. The only cardiac nerves which do not enter into the formation of
this plexus are the left superior cardiac nerve and the inferior cervical cardiac
branch from the left vagus.
The branches from the right side of this plexus pass, some in front of, and
others behind, the right pulmonary artery; the former, the more numerous, trans-
mit a few filaments to the ventral pulmonary plexus, and are then continued
onward to form part of the left or ventral coronary plexus; those behind the pul-
monary artery distribute a few filaments to the right auricle, and are then con-
tinued onward to form a part of the right or dorsal coronary plexus.
The branches from the left side of the deep cardiac plexus distribute a few
filaments to the superficial cardiac plexus, to the left auricle of the heart, and to
the ventral pulmonary plexus, and then pass on to form the greater part of the
dorsal coronary plexus.
The Ventral or Left Coronary Plexus (plexus coronarius cordis anterior}. — The
ventral or left coronary plexus is formed chiefly from the superficial cardiac
plexus, but receives filaments from the deep cardiac plexus. Passing forward
between the aorta and pulmonary artery, it accompanies the left coronary artery
on the ventral surface of the heart.
The Dorsal or Right Coronary Plexus (plexus coronarius cordis posterior}. —
The dorsal or right coronary plexus is chiefly formed by filaments prolonged
from the left side of the deep cardiac plexus, and by a few from the right side.
It surrounds the branches of the coronary artery at the back of the heart, and
its filaments are distributed with those vessels to the muscular substance of the
ventricles.
The Superficial or Ventral Cardiac Plexus. — The superficial or ventral cardiac
plexus lies beneath the arch of the aorta, in front of the right pulmonary artery.
It is formed by the left superior cardiac nerve, the left (and occasionally also the
right) inferior cervical cardiac branches of the vagus, and filaments from the
deep cardiac plexus. A small ganglion, the cardiac ganglion of Wrisberg (ganglion
cardiacum [ Wrisbergi]) is occasionally found connected with these nerves at their
point of junction. This ganglion, when present, is situated immediately beneath
the arch of the aorta, on the right side of the ductus arteriosus. The superficial
THE EPIGASTRIC OR SOLAR PLEXUS 1091
cardiac plexus forms the chief part of the ventral coronary plexus, and several
filaments pass along the pulmonary artery to the left ventral pulmonary plexus.
Valentin has described nerve filaments ramifying under the endocardium;
and Remak has found, in several mammalia, numerous small ganglia on the car-
diac nerves, both on the surface of the heart and in its muscular substance.
The Pulmonary Plexus (Plexus Pulmonalis).
The larger dorsal pulmonary plexus is situated back of the root of the lung.
It is formed by the vagus nerve and branches from the second, third, and fourth
thoracic sympathetic ganglia. It sends branches along the bronchi and blood-
vessels into the lung and some fibres pass to the front of the root of the lung to
form the ventral pulmonary plexus. The smaller ventral pulmonary plexus is
in front of and above the root of the lung. It is formed on each side by the fibres
from the dorsal pulmonary plexus. The left plexus receives branches from the
superficial cardiac plexus. The ventral plexus supplies the structures of the root
of the lung.
The (Esophageal Plexus (Plexus Oesophageus).
The cesophageal plexus is in the dorsal mediastinum and surrounds the
oesophagus. It is formed by the vagus nerves which have come from the dorsal
pulmonary plexuses, and by fibres from the great splanchnic nerve and ganglion.
The cesophageal plexus is usually considered as a portion of the vagus nerve
(p. 1072).
The Epigastric or Solar Plexus (Plexus Coeliacum) (Figs. 705, 710, 711).
The epigastric or solar plexus supplies all the viscera in the abdominal cavity.
It consists of a great network of nerves and ganglia, situated behind the pancreas
and the lesser peritoneal cavity and in front of the aorta and crura of the Dia-
phragm. It surrounds the cceliac axis and root of the superior mesenteric artery,
extending downward as low as the pancreas and outward to the suprarenal cap-
sules. This plexus, and the ganglia connected with it, receive the great, the small,
and the least splanchnic nerves of both sides, and some filaments from the right
vagus nerve. It distributes filaments which accompany, under the name of plexuses,
all the branches from the front of the abdominal aorta.
Of the ganglia of which the solar plexus is partly composed the principal
are the two semilunar ganglia (ganglia coeliaca] (Figs. 710 and 711), which are
situated one on each side of the plexus, and are the largest ganglia in the body.
They are large, irregular, gangliform masses formed by the aggregation of smaller
ganglia, having interspaces between them. They are situated in front of the
crura of the diaphragm, close to the suprarenal capsules: the one on the right
side lies beneath the postcava; the upper part of each ganglion is joined by the
greater splanchnic nerve, and to the inner side of each the branches of the solar
plexus are connected.
From the epigastric or solar plexus are derived the following :
Phrenic or Diaphragmatic plexus. ( Gastric plexus.
Adrenal plexus. Cceliac plexus < Splenic plexus.
Renal plexus. ( Hepatic plexus.
Spermatic plexus. Superior mesenteric plexus.
Aortic plexus.
1092
THE NERVE SYSTEM
The Phrenic Plexus (plexus phrenicus) (Fig. 710). — The phrenic plexus accom-
panies the phrenic artery to the Diaphragm, which it supplies, some filaments
passing to the adrenal. It arises from the upper part of the semilunar gan-
glion, and is larger on the right than on the left side. It receives one or two
branches from the phrenic nerve. In connection with this plexus, on the right
side, at its point of junction with the phrenic nerve, is a small ganglion, the
diaphragmatic or phrenic ganglion (ganglion phrenicum) (Fig. 711). This gan-
glion is placed on the under surface of the Diaphragm, near the right adrenal.
SOLAR LEFT
PHRENIC PLEXUS VAGUS
PLEXUS
RIGHT
VAGUS
HEPATIC
PLEXUS
COMMON
BILE-DUCT
SUPERIOR
MESENTERIC
PLEXUS
ABDOMINAL
AORTIC
PLEXUS
GREAT
SPLANCHNIC
SEMILUNAR
GANGLION
SUPERIOR
MESENTERIC
GANGLION
SPERMATIC
PLEXUS
LUMBAR
GANGLIA
NFERIOR
MESENTERIC
PLEXUS
FIG. 710. — The semilunar ganglia with the sympathetic plexuses of the abdominal viscera radiating from
the ganglia. (Toldt.)
Its branches are distributed to the postcava, adrenal, and hepatic plexus. There
is no ganglion on the left side.
The Adrenal Plexus (plexus suprarenalis} (Fig. 710). — The adrenal plexus
is formed by branches from the solar plexus, from the semilunar ganglion, and
from the phrenic and great splanchnic nerves, a ganglion being formed at the
point of junction of the latter nerve. It supplies the adrenal. The branches
of this plexus are remarkable for their large size in comparison with the size of
the organ they supply.
1093
The Renal Plexus (plexus renalis) (Figs. 710 and 711). — The renal plexus is
formed by filaments from the solar plexus, the outer part of the semilunar ganglion,
and the aortic plexus. It is also joined by filaments from the lesser and smallest
splanchnic nerves. The nerves from these sources, fifteen or twenty in number,
Diaphragmatic ganglion
Adrenal.
Great
splanchni
no-re.
Right
semilunar
ganglion.
Renal ganglion
Small splanchnic nerve.
Hepatic
(i)'ti'ri/.
Left semilunar ganglion.
Superior mesenteric artery.
Great splanchnic nerve.
.Small splanchnic nerve.
Renal ganglion.
Renal artery.
Superior mesenteric ganglion.
Branch to aortic plexus.
Gangliated cord of
sympathetic.
Inferior mesenteric artery.
Inferior mesenteric ganglion.
Sacro-vertebral angle.
Common iliac vein.
Common iliac artery.
FIG. 711. — Lumbar portion of the gangliated cord, with the solar and hypogastric plexuses. (After Henle.)
1094 THE NER VE SYSTEM
have numerous ganglia developed upon them. They accompany the branches
of the renal artery into the kidney, some filaments on the right side being distrib-
uted to the postcava, and others, on both sides, to the spermatic plexuses.
The Spermatic Plexus (plexus spermaticus) (Fig. 710). — The spermatic plexus
is derived from the renal plexus, receiving branches from the aortic plexus. It
accompanies the spermatic vessels to the testes.
The Ovarian Plexus (plexus arteriae ovaricae). — In the female the ovarian plexus
is distributed to the ovaries and fundus of the uterus.
The Cceliac Plexus (plexus coeliacus). — The cceliac plexus, of large size, is a
direct continuation from the solar plexus; it surrounds the cceliac axis and sub-
divides into the gastric, hepatic, and splenic plexuses. It receives branches from
the lesser splanchnic nerves, and, on the left side, a filament from the right vagus.
The Gastric or Coronary Plexus (plexus gastricus superior} (Fig. 710) accompanies
the gastric artery along the lesser curvature of the stomach, and joins with branches
from the left vagus nerve. It is distributed to the stomach.
The Splenic Plexus (plexus lienalis) (Fig. 710) is formed by branches from the
cceliac plexus, the left semilunar ganglion, and from the right vagus nerve. It
accompanies the splenic artery and its branches to the substance of the spleen,
giving off, in its course, filaments to the pancreas, the pancreatic plexus, and the
left gastro-epiploic plexus, which accompanies the gastro-epiploica sinistra artery
along the convex border of the stomach.
The Hepatic Plexus (plexus hepaticus) (Fig. 710), the largest offset from the
cceliac plexus, receives filaments from the left vagus and right phrenic nerves.
It accompanies the hepatic artery, ramifying in the substance of the liver upon
its branches and upon those of the vena portse.
Branches from this plexus accompany all the divisions of the hepatic artery.
Thus there is a pyloric plexus accompanying the pyloric branch of the hepatic,
which joins with the gastric plexus and vagus nerves. There is also a gastro-
duodenal plexus, which subdivides into the pancreatico-duodendal plexus, which
accompanies the pancreatico-duodenal artery, to supply the pancreas and duo-
denum, joining with branches from the mesenteric plexus. The gastro-epiploic
plexus, which accompanies the right gastro-epiploic artery along the greater
curvature of the stomach, and which is said to anastomose with branches from
the splenic plexus, is in reality derived from the splenic plexus. A cystic plexus,
which supplies the gall-bladder, also arises from the hepatic plexus near the liver.
The Superior Mesenteric Plexus (plexus mesentericus superior) (Fig. 710).— The
superior mesenteric plexus is a continuation of the lower part of the great solar
plexus, receiving a branch from the junction of the right vagus nerve with the
cceliac plexus. It surrounds the superior mesenteric artery, which it accom-
panies into the mesentery, and divides into a number of secondary plexuses, which
are distributed to all the parts supplied by the artery — viz., pancreatic branches to
the pancreas; intestinal branches, which supply the whole of the small intestine;
and ileo-colic, right colic, and middle colic branches, which supply the corresponding
parts of the large intestine. The nerves composing this plexus are white in color and
firm in texture, and have numerous ganglia developed upon them near their origin.
The Abdominal Aortic Plexus (plexus aorticus abdominalis) (Figs. 705, 710, and
711). — The abdominal aortic plexus is formed by branches derived, on each side,
from the solar plexus and the semilunar ganglia, receiving filaments from some
of the lumbar ganglia. It is situated upon the sides and front of the aorta,
between the origins of the superior and inferior mesenteric arteries. From this
plexus arise part of the spermatic, the inferior mesenteric, and the hypogastric
plexuses; and it distributes filaments to the postcava.
The Inferior Mesenteric Plexus (plexus mesentericus inferior) (Fig. 710) is derived
chiefly from the left side of the aortic plexus. It surrounds the inferior mesenteric
THE PELVIC OR SACRAL PLEXUS 1095
artery, and divides into a number of secondary plexuses, which are distributed to
all the parts supplied by the artery — viz., the left colic and sigmoid plexuses, which
supply the descending and sigmoid flexure of the colon; and the superior hem-
orrhoidal plexus (plexus haemorrhoidalis superior), which supplies the upper part
of the rectum and joins in the pelvis with branches from the pelvic plexus.
The Hypogastric Plexus (Plexus Hypogastricus) (Figs. 705 and 711).
The hypogastric plexus supplies the viscera of the pelvic cavity. It is situated
in front of the promontory of the sacrum, between the two common iliac arteries,
and is formed by the union of numerous filaments, which descend on each side
from the abdominal aortic plexus and from the lumbar ganglia. This plexus con-
tains no evident ganglia; it bifurcates, below, into two lateral portions, right and
left, which form the pelvic plexuses.
The Pelvic or Sacral Plexus (Plexus Sacralis).
Each pelvic plexus, sometimes called the inferior hypogastric, supplies the viscera
of the pelvic cavity, is situated at the side of the rectum in the male, while in the
female it lies in the base of the broad ligament near the ureters. It is formed by
a continuation of the hypogastric plexus, by branches from the second, third,
and fourth sacral nerves, and by a few filaments from the first two sacral ganglia.
At the points of junction of these nerves small ganglia are found. From this plexus
numerous branches are distributed to the rectum and bladder in the male and
to the rectum, bladder, uterus, and vagina in the female. They accompany the
branches of the internal iliac artery. These secondary plexuses are (1) the interior
hemorrhoidal, (2) vesical, (3) prostatic, (4) vaginal, and (5) uterine plexus.
The Inferior Hemorrhoidal Plexus (plexus haemorrhoidalis inferior). — The infe-
rior hemorrhoidal plexus arises from the back part of the pelvic plexus. It
supplies the rectum, joining with branches of the superior hemorrhoidal plexus.
The Vesical Plexus (plexus vesicalis). — The vesical plexus arises from the fore-
part of the pelvic plexus. The nerves composing it are numerous, and contain
a large proportion of spinal nerve-fibres. They accompany the vesical arteries,
and are distributed at the side and base of the bladder. Numerous filaments also
pass to the vesiculse seminales and vasa deferentia; those accompanying the vas
deferens join, on the spermatic cord, with branches from the spermatic plexus.
The Prostatic Plexus (plexus prostaticus). — The prostatic plexus is continued
from the lower part of the pelvic plexus. The nerves composing it are of large
size. They are distributed to the prostate gland, vesiculse seminales, and erectile
structure of the penis. The nerves supplying the erectile structure of the penis
consist of two sets, the small and large cavernous nerves. They are slender fila-
ments, which arise from the forepart of the prostatic plexus, and, after joining
with branches from the internal pubic nerve, pass forward beneath the pubic
arch.
The Small Cavernous Nerve (n. cavernosus penis minor) perforates the fibrous
covering of the penis near its roots.
The Large Cavernous Nerve (n. cavernosus penis major) passes forward along the
dorsum of the penis, joins with the dorsal branch of the pudic nerve, and is dis-
tributed to the corpora cavernosa and corpus spongiosum.
The uterine and vaginal plexuses in reality constitute one plexus, the utero-
vaginal plexus (plexus uterovaginalis).
The Vaginal Plexus arises from the lower part of the pelvic plexus. It is lost
on the walls of the vagina, being distributed to the erectile tissue at its ventral
1096 THE NERVE SYSTEM
part and to the mucous membrane. The nerves composing this plexus contain,
like the vesical nerves, a large proportion of spinal nerve-fibres.
The Uterine Plexus arises from the upper part of the pelvic plexus above the
point where the branches from the sacral nerves join the plexus. Its branches
accompany the uterine arteries to the sides of the organ between the layers of the
broad ligaments, and are distributed to the cervix and lower part of the body of
the uterus, penetrating its substance.
Other filaments pass separately to the body of the uterus and the oviduct.
Branches from the plexus accompany the uterine arteries into the substance
of the uterus. Upon these filaments ganglionic enlargements are found.
THE OKGANS OF SPECIAL SENSE.
Organs of the Senses are five in number— viz., those of Taste, of Smell,
of Sight, of Hearing, and of Touch.
THE TONGUE (LINGUA) (Fig. 712).
The tongue is a very mobile muscular organ, undergoing changes in length and
width at every contraction of its muscle. It is the organ of the special sense of
taste, and is also an organ of speech, mastication, and deglutition. It is situated
in the floor of the mouth, in the interval between the two lateral portions of the
body of the lower jaw, and when at rest is about three and one-half inches in
length. We describe the body, base, apex, dorsum, margin, and inferior surface.
The Body (corpus linguae}. — The body forms the great bulk of the organ
and is composed of striated muscle.
The Base or Root (radix linguae). — The base or root is directed backward, and
connected with the os hyoideum by the Hyo-glossi and Genio-hyo-glossi muscles
and the hyo-glossal membrane ; with the epiglottis by three folds of mucous mem-
brane, the glosso-epiglottic folds ; with the soft palate by means of the anterior
pillars of the fauces; and with the pharynx by the Superior constrictors and the
mucous membrane.
The Apex or Tip (apex linguae). — The apex or tip is thin and narrow, and is
directed forward against the inner surface of the lower incisor teeth.
The Dorsum of the Tongue (dorsum linguae). — The dorsum when the tongue
of a living person is at rest is markedly arched from before backward. On the
dorsum is a median longitudinal raph6 (sulcus medianus linguae). This slight
depression terminates posteriorly in the depression known as the foramen caecum
(foramen caecum linguae [Morgagnii\), from which a shallow-shaped groove, the
sulcus terminalis of His, runs outward and forward on each side to the lateral
margin of the tongue. The part of the dorsum of the tongue in front of this
groove, known as the anterior or oral part, forming about two-thirds of its upper
surface, is rough and covered with papillae; the posterior third of the dorsum
is back of the sulcus terminalis, is known as the posterior or pharyngeal portion, is
smoother, and contains numerous muciparous glands and lymphoid follicles.
The Margin of the Tongue (margo lateralis linguae). — The margin of the
tongue is free in front of the anterior arch of the palate. Just in front of the
arch are several vertical folds, the folia linguae.
The Under or Inferior Surface (fades inferior linguae). — The under or
inferior surface of the tongue is connected with the lower jaw by the Genio-hyo-
glossi muscles, from its sides the mucous membrane is reflected to the inner sur-
face of the gums; and from its under surface'on to the floor of the mouth, where,
in the middle line, it is elevated into a distinct vertical fold, the fraenum linguae
(frenulum linguae). To each side of the fraenum is a slight fold of the mucous
membrane, the plica fimbriata, the free edge of which exhibits a series of fringe-
like processes.
The tip of the tongue, part of the under surface, its sides, and dorsum are free.
( 1097 )
1098
THE ORGANS OF SPECIAL SENSE
Structure of the Tongue. — The tongue is partly invested by mucous mem-
brane and a submucous fibrous layer. It consists of symmetrical halves, sepa-
rated from each other, in the middle line, by a fibrous septum. Each half is com-,
posed of muscular fibres arranged in various directions (page 400), containing
much interposed fat, and supplied by vessels and nerves.
The Mucous Membrane (tunica mucosa linguae). — The mucous membrane
invests the entire extent of the free surface of the tongue. On the dorsum it is
thicker behind than in front, and is continuous with the sheath of the muscles
attached to it, through the submucous fibrous layer. On the under surface of the
organ, where it is thin and smooth, it can be traced on each side of the fraenum
NSIL.
-EPIGLOTTIS.
CIRCUM-
VALLATC
PAPILL/E.
FIG. 712. — Upper surface of the tongue.
through the ducts of the submaxillary and the sublingual glands. As it passes
over the borders of the organ it gradually assumes a papillary character.
Structure. — The structure of the mucous membrane of the tongue differs in
different parts. That covering the under surface of the organ is thin, smooth,
and identical in structure with that lining the rest of the oral cavity. The mucous
membrane covering the tongue behind the foramen caecum and sulcus terminalis
is thick and freely movable over the subjacent parts. It contains a large number
of lymphoid follicles (folliculi linguales}, which together constitute what is some-
times termed the lingual tonsil (tonsilla lingualis). Each follicle forms a rounded
eminence, the centre of which is perforated by a minute orifice leading into a
THE TONGUE
1099
funnel-shaped cavity or recess; around this recess are grouped numerous oval or
rounded nodules of lymphoid tissue, each enveloped by a capsule derived from
the submucosa, while opening into the bottom of the recesses are also seen the
ducts of mucous glands (glandulae linguales). The mucous membrane on the
anterior part of the dorsum of the tongue is thin and intimately adherent to the
muscular tissue, and covered with minute eminences, the papillae of the tongue.
It consists of a layer of connective tissue, the corium or mucosa, supporting numer-
ous papillae, and covered, as well as the papillae, with epithelium.
The epithelium is of the scaly variety, like that of the epidermis. It covers the
free surface of the tongue, as maybe readily demonstrated by maceration or boiling,
when it can be easily detached entire; it is much thinner than that of the skin; the
intervals between the large papillae are not filled up by it, but each papilla has
a separate investment from root to summit. The deepest cells may sometimes be
detached as a separate layer, corresponding to the rete mucosum, but they never
contain coloring matter.
The Corium. — The corium consists of a dense feltwork of fibrous connective
tissue, with numerous elastic fibres, firmly connected with the fibrous tissue form-
ing the septa between the muscular bundles of the tongue. It contains the ramifi-
cations of the numerous vessels (Fig. 713) and nerves from which the papillae are
supplied, large plexuses of lymphatic vessels, and the glands of the tongue.
Filiform,
Fungiform.
Secondary
Circumvallate.
Artery.
Vein.
Artery.1
Vein.
FIG. 713. — Three kinds of papillae, magnified.
The Papillae of the Tongue (papillae linguales) (Figs. 712, 713, 714, and 715).—
These are papillary projections of the corium. They are thickly distributed over
the anterior two-thirds of the upper surface of the tongue, giving to it its char-
acteristic roughness. The varieties of papillae met with are — the papillae maximae
or circumvallate papillae, papillae mediae or fungiforme papillae, papillae minimae,
conical or filiform e papillae, and papillae simplices or simple papillae.
The Papillae Maximae or Circumvallate Papillae (papillae vallatae (Figs. 712, 713,
and 714) are of large size, and vary from eight to twelve in number. They are
situated at the back part of the dorsum of the tongue, near its base, in front of
the foramen caecum and sulcus terminalis, forming a row on each side, which,
running backward and inward, meet in the middle line, like the two lines of the
letter V inverted A.. Each papilla consists of a projection of mucous membrane
from -j1^ to YJ °f an inch wide, attached to the bottom of a cup-shaped depression of
the mucous membrane; the papilla is in shape like a truncated cone, the smaller
end being directed downward and attached to the tongue, the broader part or
base projecting on the surface and being studded with numerous small secondary
papillae (Fig. 713), which, however, are covered by a smooth layer of the epithe-
lium. The cup-shaped depression forms a kind of fossa around the papilla,
having a circular margin of about the same elevation covered with smaller papillae.
1100
Immediately behind the apex of the V is the foramen caecum, mentioned above.
This foramen, according to His, represents the remains of the invagination which
forms the median rudiment of the thyroid body, and which for a time opens by
a duct, the thyroglossal duct (ductus thyreoglossus] , on to the dorsum of the tongue.
It may extend downward toward the hyoid bone. Kanthack, however, disputes
. this view.1
The Fungiforme Papillae or Papillae Mediae (papillae fungiformes el papillae len-
ticulares) (Fig. 713), -more numerous than the preceding, are scattered irregularly
and sparingly over the dorsum of the tongue, but are found chiefly at its sides
and apex. They are easily recognized among the other papillae, by their large
size, rounded eminences, and deep-red color. They are narrow at their attach-
ment to the tongue, but broad and rounded at their free extremities, and are
covered with secondary papillae. Their epithelial investment is very thin.
The Conical or Filiform Papillae or Papillae Minimae (papillae conicae et papillae
filiformes) (Fig. 713) cover the anterior two-thirds of the dorsum of the tongue.
They are very minute, more or less conical or filiform in shape, and arranged in lines
corresponding in direction with the two rows of the papillae circumvallatae, except-
ing at the apex of the organ, where their direction is transverse. Projecting from their
apices are numerous filiform processes or secondary papillae; these are of a whitish
tint, owing to the thickness and density of the epithelium of which they are com-
posed, and which has here undergone a
peculiar modification, the cells having be-
come cornified and elongated into dense,
imbricated, brush-like processes. They
contain also a number of elastic fibres, which
render them firmer and more elastic than
the papillae of mucous membrane generally.
Simple Papillae, similar to those of the skin,
cover the whole of the mucous membrane of
the tongue, as well as the larger papillae.
They consist of closely set, microscopic ele-
vations of the corium, containing a capillary
loop, covered by a layer of epithelium.
Structure of the Papillae (Figs. 713and 714).
— The papillae apparently resemble in struc-
ture the papillae of the cutis, consisting of a
cone-shaped projection of connective tissue,
FIG. 714. — Circumvallate papillae of tongue of i-,iji*ii p •
rabbit, showing position of taste-goblets. a. COVCred With a thick layer OI SquaniOUS epl-
Duct of gland, a. Serous gland, g. Taste-buds. .1 i- j '11
i. Primary septa, and i', secondary sepia, of thelium, and contain one or more capillary
fibresae'(Stncihr]V)edullated nerve- Muscular loops, amongst which nerves are distributed
in great abundance. If the epithelium is
removed, it will be found, however, that they are not simple elevations like the
papillae of the skin, for the surface of each is studded with minute conical pro-
cesses of the mucous membrane, which form secondary papillae (Todd and Bow-
man). In the papillae circumvallatae the nerves are numerous and of large size; in
the papillae fungiformes they are also numerous, and terminate in a plexiform net-
work, from which brush-like branches proceed; in the papillae filiformes their mode
of termination is uncertain. Buried in the epidermis of the papillae circumvallatae,
and in some of the fungiformes, are certain peculiar bodies, called taste-buds2 (Fig.
715). Each is flask-like in shape, the broad base resting on the corium, and the
neck opening by an orifice, the gustatory pore, between the cells of the epithelium.
1 Journal of Anatomy and Physiology, 1891.
2 These bodies are also found in considerable numbers at the side of the base of the tongue, just in front of the
anterior pillars of the fauces, and also on the posterior surface of the epiglottis and anterior surface of the soft
palate. — ED. of 15th English edition.
THE TONGUE HOI
They are formed by two kinds of cells, supporting cells and gustatory cells. The
supporting cells are mostly arranged like the staves of a cask, and form an outer
envelope for the bud. Some, however, are found in the interior of the bud between
the gustatory cells. The gustatory cells occupy the central portion of the bud;
they are spindle-shaped, and each possesses a large spherical nucleus near the
middle of the cell. Until recently the teaching was as follows : The peripheral
end of the cell terminates as the gustatory pore in a fine, hair-like filament, the
gustatory hair. The central process passes toward the deep extremity of the bud,
and there ends in a single or bifurcated varicose filament, which was formerly
supposed to be continuous with the terminal fibril of a nerve; the investigations
of Lenhosse"k and others would seem to prove, however, that this is not so, but
that the nerve-fibrils after losing their medullary sheaths enter the taste-bud, and
Gustatory hairs
Epithelium
Taste bud
Tunica propria-
FIG. 715. — Taste-buds from the papilla foliata of a rabbit. X 850. (Szymonowicz.)
terminate in a fine extremity between the gustatory cells. Other nerve-fibrils
may be seen ramifying between the cortical cells and terminating in fine extrem-
ities; these, however, are believed to be nerves of ordinary sensation, and not
gustatory. It is now not believed that the epithelia of the taste-buds are directly
connected with the nerve-fibres by long processes. "The latest researches have
shown that dendrites of sensor neurones (sensor nerves) enter the taste-buds
and end free in telodendria. The latter surround the neuro-epithelial, and, to
some extent, the sustentacular cells, their relations depending on contact."1
Glands of the Tongue. — The tongue is provided with mucous and serous glands.
The mucous glands are similar in structure to the labial and buccal glands. They
are found especially at the back part, behind the circumvallate papillae, but are
also present at the apex and marginal parts. In connection with these glands
special ones have been described by Blandin and Nuhn. They are known as the
glands of Nuhn and Blandin or apical glands (glandulae linguales anteriores of Nuhn
and Blandin) (Fig. 716). They are situated near the apex of the tongue on either
side of the fraenum, and each is covered over by a fasciculus of muscular fibre
derived from the Stylo-glossus and Inferior lingualis muscles. Each gland is from
half an inch to nearly an inch long and about the third of an inch broad. It has
from four to six ducts, which open on the under surface of the apex.
The Serous Glands or Glands of v. Ebner occur only at the back of the tongue in
the neighborhood of the taste-buds, their ducts opening for the most part into the
1 Text-book of Histology. By A. A. Bohm and M. von Davidoff. Edited by G. Carl Huber.
1102
THE ORGANS OF SPECIAL SENSE
fossae of the papillae circumvallatae. These glands are racemose, the duct branch-
ing into several minute ducts, which terminate in alveoli lined by a single layer
of more or less columnar epithelium. Their secretion is of a watery nature, and
probably assists in the distribution of the substance to be tasted over the taste-
area (Ebner).
The Hyo-glossal membrane is a strong fibrous lamina which is derived from the
septum of the tongue and which connects the under surface of the base of the
tongue to the body of the hyoid bone. This membrane receives, in front, some
of the posterior fibres of the Genio-hyo-glossi muscles.
The Vessels of the Tongue. — The arteries of the tongue are derived from the
lingual, the facial, and ascending pharyngeal. The veins of the tongue open into
the internal jugular.
The lingual artery (Fig. 718) on each side passes forward beneath the Hyo-
glossus muscle and courses to the apex of the tongue, between the Genio-glossus
and the Inferior lingual muscles, about one-eighth of an inch from the surface.
It divides into the ranine (Fig. 716) and sublingual (Fig. 718). Near the apex a
branch is given off from the ranine artery, which penetrates the septum and joins
a like branch from the other side. The dorsalis linguae is a branch of the lingual
Bristles
in ducts
of glands.
Glands of
\ Blandin
or Nuhn.
Lingual nerve. Ranine artery.
FIG. 716. — Under surface of tongue, showing position and relations of gland of Blandin or Nuhn.
a preparation in the Museum of the Royal College of Surgeons of England.)
(from
supplying the posterior part of the tongue, and rami from the tonsillar branch
of the facial go to the same region. A network of capillary vessels is placed
beneath the epithelium.
The ranine veins lie to the sides of the fraenum underneath the mucous mem-
brane. Each ranine vein runs backward, superficial to and upon the Hyo-glossus
muscle and near to the hypo-glossal nerve. The venae comites of the lingual artery
usually join the ranine vein, and the trunk opens into the internal jugular vein,
but the vessels may open separately into the jugular (Fig. 445).
The Muscles of the Tongue. — The muscular fibres of the tongue run in various
directions. These fibres are divided into two sets, Extrinsic and Intrinsic, which
have already been described (pp. 398, 399, 400, 401, and 4Q2).
THE TONGUE
1103
The Extrinsic come from the Stylo-glossus, Hyo-glossus, Genio-glossus,
Palato-glossus, and Chondro-glossus. The Intrinsic muscles are the Superior
lingualis (m. longitudinalis superior), the Inferior lingualis (m. longitudinalis
inferior], the Transverse lingual (m. transversus linguae), and the Vertical lingual
(m. verticalis linguae). The outer or cortical portion of the tongue is composed
chiefly of longitudinal fibres. The central or medullary portion is composed chiefly
of vertical and transverse fibres and is divided into two parts by a vertical sep-
tum (septum linguae), which is a fibrous structure, beginning at the apex and
passing back. As it approaches the back it becomes narrower vertically and
broadens out transversely to form the hyo-glossal membrane. The fibrous septum
is well displayed by making a vertical section of the tongue.
The Lymphatic Vessels of the Tongue (Fig. 490). — The lymphatic vessels from
the anterior half of the tongue pass to the submaxillary lymph glands.
Lymph vessels from the posterior half of the tongue are connected with satellite
glands on the Hyo-glossus muscle and terminate in the deep cervical glands. The
last-named lymph- vessel accompanies the ranine vein. The lingual lymphatics
arise from a network beneath the epithelium. Across the anterior two-thirds
of the tongue there is little or no lymphatic connection between the two sides;
in the posterior one-third there is free connection.
SUPERIOR
LONGITUDINALIS
MUSCLE
VERTICALIS,
LINGUAE MUSCLE
TRANSVERSUS
LINGUAE MUSCLE
INFERIOR
LONGITUDINALIS
MUSCLE
STYLOGL06SUS
MUSCLE
DEEP LINGUAL
ARTERY
SUBLINGUAL
GLAND
GENIOGLOSSUS
MUSCLE
FIG. 717. — Frontal section through the body of the tongue of a new-born babe. X 3. (Spalteholz.)
The Nerves of the Tongue (Fig. 718). — The nerves of the tongue are five in number
in each half: the lingual branch of the inferior maxillary division of the trigeminal,
which is distributed to the papillae at the forepart and sides of the tongue, and forms
the nerve of ordinary sensibility for its anterior two-thirds; the chorda tympani,
which runs in the sheath of the lingual, is generally regarded as the nerve of
taste for the same area (p. 898) ; the lingual branch of the glosso-pharyngeal, which
is distributed to the mucous membrane at the base and sides of the tongue, and
to the papillae circumvallatae, and which supplies both sensory and gustatory
filaments to this region; the hypo-glossal nerve, which is the motor nerve to the
muscular substance of the tongue ; and the internal laryngeal branch of the superior
laryngeal, which sends some fine branches to the root near to the epiglottis.
Sympathetic filaments also pass to the tongue from the nervi molles on the
lingual and other arteries supplying it. Some of the nerves end free between the
cells of epithelium; others terminate as end organs (Meissner's corpuscles and
the end-bulbs of Krause), and in taste-buds as sensory dendrites (p. 833).
Surgical Anatomy. — The diseases to which the tongue is liable are numerous, and its sur-
gical anatomy is of importance, since any or all the structures of which it is composed — muscles,
connective tissue, mucous membrane, glands, vessels, nerves, and lymphatics — may be the seat
of morbid changes. It is not often the seat of congenital defects, though a few cases of vertical
1104
THE ORGANS OF SPECIAL SENSE
cleft have been recorded, and it is occasionally, though much more rarely than is commonly sup-
posed, the seat of tongue-tie, from shortness of the fraenum.
There is, however, one condition which must be regarded as congenital, though not uncom
monly it does not exhibit the significant changes until a year or two after birth. This is an
enlargement of the tongue which is due primarily to a dilatation of the lymph-channels and a
greatly increased development of the lymphatic tissue throughout the tongue (macroglossia). This
is often aggravated by inflammatory changes induced by injury or exposure, and the tongue may
assume enormous dimensions and hang out of the mouth, giving the child an imbecile expression.
The treatment consists in excising a V-shaped portion and bringing the cut surfaces together
with deeply placed silver sutures. Compression has been resorted to in some cases with occa-
sional success, but it is difficult to apply. Acute inflammation of the tongue (acute glossitis),
which may be caused by injury or the introduction of some septic or irritating matter, and it
is attended by great swelling from infiltration of the connective tissue of the tongue; this con-
nective tissue is present in considerable quantity. The great swelling renders the patient
incapable of swallowing or speaking, and may seriously impede respiration. The condition may
eventuate in suppuration and the formation of an acute abscess. Chronic abscess, which has
been mistaken for cancer, may also occur in the substance of the tongue.
Sublingual
\ artery.
Glosso-pharyn-
geal nerve.
Internal laryngeal
branch of the
superior laryngeal
nerve.
FIG. 718. — Under surface of tongue, showing the distribution of nerves to this organ. (From a preparation
in the Museum of the Royal College of Surgeons of England.)
The mucous membrane of the tongue may become chronically inflamed, and presents different
appearances in different stages of the disease, to which the terms leucoplakia, psorias, and
ichthyosis have been given.
The tongue, being very vascular, is often the seat of naevoid growths, and these have a tendency-
to grow rapidly.
The tongue is frequently the seat of ulceration, which may arise from many causes, as from
the irritation of jagged teeth, dyspepsia, tuberculosis, syphilis, and cancer. Of these the cancerous
ulcer is the most important, and probably also the most common. The variety is the squamous
epithelioma, which soon develops into an ulcer with an indurated base. It produces great pain
which speedily extends to all parts supplied with sensation by the trigeminal nerve, especially to the
THE NOSE H05
region of the ear. The pain in these cases is conducted to the ear and temporal region by the
lingual nerve, and from this nerve pain radiates to the other branches of the inferior maxillary
nerve, especially the auriculo-temporal. Possibly pain in the ear itself may be due to implication
of the fibres of the glosso-pharyngeal nerve, which by its tympanic branch reaches the tympanic
plexus. Cancer of the tongue spreads through the organ very rapidly because of the almost
constant muscular movements.
Cancer of the tongue may necessitate removal of a part or the whole of the organ, and many
different methods have been adopted for its excision. It may be removed from the mouth by
the e"craseur or the scissors. The better method is by the scissors, usually known as Whitehead's
method. The mouth is widely opened with a gag the tongue is transfixed with a stout silk liga-
ture, by which to hold and make traction on it and the reflection of mucous membrane from
the tongue to the jaw, and the insertion of the Genio-hyo-glossi first divided with a pair of
curved blunt scissors. The Palato-glossi are aiso divided. The tongue can now be pulled well
out of the mouth. The base of the tongue is cut through by a series of short snips, each bleed-
ing vessel being dealt with as soon as divided, until the situation of the ranine artery is reached.
The remaining undivided portion of tissue is to be seized with a pair of Wells's forceps, the tongue
removed, and the vessel secured. In the event of the ranine artery being accidentally injured
early in the operation, hemorrhage can be at once controlled by passing two fingers over the
dorsum of the tongue as far as the epiglottis and dragging the root of the tongue forcibly forward.
In cases where the disease is confined to one side of the anterior portion of the tongue this
operation may be modified by splitting the tongue down the centre and removing only the affected
half. If the posterior portion of the tongue is attacked by cancer the entire tongue must be
removed, even if but one side of the organ is apparently involved. The exchange of lymph
between the halves of the posterior portion of the tongue makes it certain that the opposite half
becomes involved soon after the origin of the disease. Whatever operation is performed for
cancer of the tongue, the glands must be removed ^rom both sides of the neck. This is to be
done, even if but one side of the tongue is removed. Kocher; after performing a preliminary trache-
otomy, removes the tongue from the neck; by an incision taken from near the lobule of the ear,
down the anterior border of the Sterno-mastoid to the level of the great cornu of the hyoid bone,
then forward to the body of the hyoid bone, and upward to near the symphysis of the jaw. The
lingual artery is now secured and by a careful dissection the submaxillary lymphatic glands
and the tongue removed. Regnoli advocated the removal of the tongue by a semilunar incision
in the submaxillary triangle along the line of the lower jaw. and a vertical incision from the
centre of the semilunar one backward to the hyoid bone. Care must be taken not to carry the
first incision too far backward, so as to wound the facial arteries. The tongue is thus reached
through the floor of the mouth pulled out through the external incision, and removed with the
knife. The great objection to this operation is that all the muscles which raise the hyoid
bone and larynx are divided, and that therefore the movements of deglutition and respiration are
interfered with.
Finally, where both sides of the floor of the mouth are involved in the disease, or where very
free access is required on account of the extension backward of the disease to the pillars of the
fauces and the tonsil, or where the lower jaw is involved, the operation recommended by Syme
must be performed. This is done by an incision through the central line of the lip- across the
chin, and down as far as the hyoid bone. The lower jaw is sawed through at the symphysis, and
the two halves of the bone forcibly separated from each other. The mucous membrane is sepa-
rated from the bone, and the Genio-hyo-glossi detached from the bone, and the Hyo-glossi
divided. The tongue is then drawn forward and removed close to its attachment to the hyoid
bone. Adjacent lymph glands can be removed and if the bone is implicated in the dis-
ease, it can also be removed by freeing it from the soft parts externally and internally, and
making a second section with the saw beyond the diseased part.
Formerly many surgeons before removing the tongue performed a preliminary tracheotomy:
(1) to prevent blood entering the air-passages; and (2) to allow the patient to breathe through
the tube and not inspire air which had passed over a sloughy wound, and which was loaded with
septic organisms and likely to induce septic pneumonia. By operating with the patient in the
Trendelenburg position, the blood is caused to flow away from the air-passages. By the judicious
use of iodoform the evil mentioned secondly may be obviated, and the preliminary tracheotomy is
now usually dispensed with.
THE NOSE.
The nose is the peripheral portion of the organ of smell (organon olfactus) : by
means of the peculiar properties of its nerves it protects the lungs from the inhala-
tion of deleterious gases and assists the organ of taste in discriminating the prop-
erties of food. The organ of smell consists of two parts; one external, the outer
nose; the other internal, the nasal fossae
70
1106
THE ORGANS OF SPECIAL SENSE
THE OUTER NOSE (NASUS EXTERNUS).
The outer nose is the more anterior and prominent part of the organ of smell.
Of a triangular form, it is directed downward, and projects from the centre of
the face, immediately above the upper lip. Its summit or root (radix nasi) is
connected directly with the forehead. Its inferior part or base (basis nasi) pre-
sents two elliptical orifices, the nostrils or anterior nares (nares), separated from
each other by an antero-posterior septum, the mobile septum or columna nasi
(septum mobile nasi). The margins of the nostrils are provided with a number
of stiff hairs or vibrissae, which arrest the passage of foreign substances carried
with the current of air intended for respiration. The point (apex nasi) is the free
extremity of the nose. The lateral surfaces of the nose form, by their union in
the middle line, the dorsum (dorsum nasi), the direction of which varies considerably
in different individuals. The portion of the dorsum over the nasal bones is the
bridge. Each lateral surface terminates below in a rounded eminence, the wing
or ala nasi, which, by its lower margin (margo nasi), forms the outer boundary
of the corresponding nostril. Above the ala is a depression, the alar sulcus.
Seen from below.
Side view.
Lower lateral cartilage.
Sesamoid cartilages,
FIGS. 719 and 720. — Cartilages of the nose.
Structure. — The nose is composed of a framework of bones and cartilages, the
latter being slightly acted upon by certain muscles. It is covered externally by the
integument, internally by mucous membrane, and is supplied with vessels and nerves.
The Bony Framework. — The bony framework occupies the upper part of the
organ; it consists of the nasal bones and the nasal processes of the superior maxillary
bones (pp. 104 and 109).
The Cartilaginous Framework (cartilagines nasi) (Figs. 719 and 720). — The car-
tilaginous framework consists of five pieces, the two upper and the two lower
lateral cartilages and the cartilage of the septum.
The Upper Lateral Cartilage (cartilago nasi lateralis) of each side is situated below
the free margin of the nasal bone. It is flattened and triangular in shape. Its ante-
rior margin is thicker than the posterior, and continuous with the cartilage of the
septum. Its posterior margin is attached to the nasal process of the superior
maxillary and nasal bones. Its inferior margin is connected by fibrous tissue with
the lower lateral cartilage; one surface is turned outward, the other inward toward
the nasal cavity.
THE OUTER NOSE
1107
The Lower Lateral Cartilage, the Cartilage of the Aperture or the Greater Alar Car-
tilage ( cartilago alaris major) of each side consists of two thin, flexible plates situated
immediately below the preceding, and bent upon themselves in such a manner as
to form the inner and outer walls of the orifice of the nostril. The portion which
forms the inner wall (crus mediale), thicker than the rest, is loosely connected with
the corresponding portion of the opposite cartilage, and forms a small part of the
columna. Its inferior border, free, rounded, and projecting, forms, with the thick-
ened integument and subjacent tissue and the corresponding parts of the opposite
side, the mobile septum. The part of the cartilage which forms the outer wall (crus
latcrale) is curved to correspond with the ala of the nose; it is oval and flattened,
narrow behind, where it is connected with the nasal process of the superior maxilla
by a tough fibrous membrane, in which are found three or four small cartilaginous
plates, the sesamoid, accessory quadrate or lesser alar cartilages (cartilagines alares
minores}. Above, it is connected by fibrous tissue to the upper lateral cartilage
and front part of the cartilage of the septum; below, it falls short of the margin
of the nostril; the ala being formed by dense cellular tissue covered by skin. In
front the lower lateral cartilages are separated by a notch which corresponds
with the point of the nose.
The Triangular Cartilage of the Septum (cartilago septi nasi) (Figs. 719 and 721)
is somewhat quadrilateral in form, thicker at its margins than at its centre, and
completes the separation between the
nasal fossae in front. Its anterior
margin, thickest above, is connected
with the nasal bones, and is continuous
with the anterior margins of the two
upper lateral cartilages. Below, it is
connected to the inner portions of the
lower lateral cartilages by fibrous
tissue. Its posterior margin is con-
nected with the perpendicular lamella
of the ethmoid ; its inferior margin with
the vomer and the palate processes of
the superior maxillary bones (Fig. 103).
It may be prolonged backward
(especially in children) for some dis-
tance between the vomer and perpen-
dicular plate of the ethmoid, forming
what is termed the sphenoidal process
(processus sphenoidalis septi cartilaginei). The septal cartilage does not reach
as far as the lowest part of the nasal septum. This is formed by the inner
portions of the lower lateral cartilages and by the skin ; it is freely movable, and
hence is termed the mobile septum.
Along the lower margin of the anterior half of the cartilage of the septum is
another cartilage which is attached to the vomer and is known as the vomerine
cartilage or cartilage of Jacobson (cartilago vomeronasalis) .
These various cartilages are connected to each other and to the bones by a tough
fibrous membrane, which allows the utmost facility of movement between them.
The Muscles of the Nose. — The muscles of the nose are situated beneath the
integument; they are (on each side) the Pyramidalis nasi, the Levator labii supe-
riores alaeque nasi, the Dilatator naris, anterior and posterior, the Compressor
nasi, the Compressor narium minor, and the Depressor alae nasi. They have been
previously described (p. 378).
The Integument covering the dorsum and sides of the nose is thin, and loosely
connected with the subjacent parts; but the integument of the tip and the alae of
FIG. 721. — Bones and cartilages of septum of the nose.
Right side.
1108
THE ORGANS OF SPECIAL SENSE
the nose is thicker and more firmly adherent, and is furnished with a large number
of sebaceous follicles, the orifices of which are usually very distinct.
The Mucous Membrane lining the interior of the nose is continuous with the
skin externally and with the mucous membrane which lines the nasal fossae within.
The Arteries of the Outer Nose. — The arteries of the nose are the lateralis nasi from
the facial, and the inferior artery of the septum from the superior coronary, which
supply the alae and septum, the sides and dorsum being supplied from the nasal
branch of the ophthalmic and the infraorbital.
The Veins of the Outer Nose. — The veins of the nose terminate in the facial and
ophthalmic.
The Lymphatics of the Outer Nose. — These vessels are shown in Figs. 486, 488,
and 489. They empty chiefly into the submaxillary lymph glands.
The Nerves of the Outer Nose.— The nerves for the muscles of the nose are derived
from the facial, while the skin receives its branches from the infraorbital, infra-
trochlear, and nasal branches of the ophthalmic.
THE NASAL FOSSAE (CAVUM NASI).
The nasal fossae are two irregular cavities situated in the middle of the face,
one on each side of the middle line, and extending from before backward. They
open in front, when the soft parts are in place, by the two nostrils or anterior nares,
and terminate, behind, in the naso-pharynx by the posterior nares.
FIG. 722. — External wall of right nasal fossa, parts of the turbinates having been cut away to show the
orifices of the sinuses which open into the meatuses. (Testut.)
The Anterior Nares (nares). — The anterior nares are somewhat pear-shaped
apertures, each measuring about one inch antero-posteriorly and half an inch
transversely at their widest part. The nasal fossae in the dry skull open in front
by the anterior nasal aperture (apertura pyriformis).
The Posterior Nares (choanae). — The posterior nares are two oval openings,
which are smaller in the living or recent subject than in the skeleton, because they
THE NASAL FOSSAE
1109
are narrowed by the mucous membrane. Each measures an inch in the vertical
and half an inch in the transverse direction in a well-developed adult skull.
For the description of the bony boundaries of the nasal fossae see section on
.Osteology (p. 143).
Inside the aperture of the nostril is a slight dilatation, the vestibule (vestibulum
iiaxi), which extends as a small pouch, the ventricle, toward the point of the nose.
Above and behind the vestibule is surrounded by a prominence (limen nasi}.
Below the prominence the vestibule is lined with skin; above and behind it the
fossa is lined with mucous membrane. The fossa, above and behind the vestibule,
has been divided into two parts: an olfactory portion (regio olfactoria), a slit-like
cavity, comprising the upper and central part of the septum and probably the
superior turbinated bone, and a respiratory portion (regio respiratoria) , which com-
prises the rest of the fossa.
Eye-ball
Groove (hiatus semilunaris)
leading to infundibulum
Middle turbinated bone
Middle meatus
Antrum of Highmore
Inferior meatus
Inferior turbinated bone
f Buccal cavity
\ Space between cheek and gum
Molar tooth, upper jaw
of molar tooth
Inferior dental nerve
FIG. 723. — Transverse vertical section of the nasal fossae. The section is made anterior to the superior
turbinated bones. (Cryer.)
Outer Wall (Figs. 722 and 723). — The superior, middle, and inferior meatus
(meatus nasi superior, medius, and inferior] are described on pages 144 and 145.
The sphenoidal air sinus opens into the spheno-ethmoidal recess (recessus spheno-
ethmoidalis), a narrow recess above the superior turbinated bone (Fig. 722). The
posterior ethmoidal cells (cellula ethmoidalis posterior) open into the front and upper
part of the superior meatus (Fig. 722). On raising or cutting away the middle tur-
binated bone the outer wall of the middle meatus is fully exposed (Figs. 722 and
723) and presents (1) a rounded elevation, termed the bulla ethmoidalis, opening
on or immediately above which are the orifices of the middle ethmoidal cells; (2) a
1110 THE ORGANS OF SPECIAL SENSE
deep, narrow, curved groove, in front of the bulla ethmoidalis, termed the hiatus
semilunaris, into which the anterior ethmoidal cells (cellula ethmoidalis anterior}
and the antrum of Highmore (sinus maxillaris] open, the orifice of the latter being
placed near the level of its roof. The middle meatus is prolonged, above and in
front, into the infundibulum (infundibulum ethmoidale), which leads into the frontal
sinus (sinus frontal is). The anterior extremity of the meatus is continued into a
depressed area which lies above the vestibule and is named the atrium (atrium
meatus medii mm"). The nasal duct (ductus nasalis) opens into the anterior part
of the inferior meatus, the opening being frequently overlapped by a fold of
mucous membrane, and from the orifice of the duct a groove leads downward
and forward.
The Inner Wall (Fig. 723). — The inner wall or septum is frequently more or less
deflected from the mesal plane (Figs. 101 and 723), thus limiting the size of one
fossa and increasing that of the other. Ridges or spurs of bone growing outward
from the septum are also sometimes present. Immediately over the incisive
foramen at the lower edge of the cartilage of the septum a depression, the naso-
palatine recess (recessus nasopalatinus} , may be seen. In the septum close to this
recess a minute orifice may be discerned ; it leads into a blind pouch, the rudi-
mentary organ of Jacobson (organon vomeronasale) , which is well developed in
some of the lower animals, but is rudimentary in man. The organ is supported
by a plate of cartilage, distinct from the cartilage of the septum, the cartilage of
Jacobson (p. 1107). The cartilage of Jacobson is to the outer side of the lower
edge of the cartilage of the septum. The diverticulum opens anteriorly near the
floor of the nose and close by Stenson's foramen. Just below the opening of
the blind pouch is an elevation, the eminence of Jacobson.
The Mucous Membrane (membrana mucosa nasi). — The mucous membrane lining
the nasal fossae is called the pituitary, from the nature of its secretion ; or Schneide-
rian, from Schneider, the first anatomist who showed that the secretion proceeded
from the mucous membrane, and not, as was formerly imagined, from the brain.
It is intimately adherent to the periosteum or perichondrium, over which it lies.
It is continuous externally with the skin through the anterior nares, and with the
mucous membrane of the naso-pharynx through the posterior nares. From the
nasal fossae its continuity may be traced with the conjunctiva through the nasal
duct and lachrymal canals ; with the lining membrane of the tympanum and mas-
toid cells through the Eustachian tube; and with the frontal, ethmoidal, and
sphenoidal sinuses, and the antrum of Highmore through the several openings in
the meatuses. The mucous membrane is thickest and most vascular over the
turbinated bones. It is also thick over the septum, but in the intervals between
the spongy bones and on the floor of the nasal fossae it is very thin. Where it
lines the various sinuses and the antrum of Highmore it is thin and pale.
Owing to the great thickness of this membrane, the nasal fossae are much
narrower, and the turbinated bones, especially the lower ones, appear larger and
more prominent than in the skeleton. From the same circumstances also the
various apertures communicating with the meatuses are considerably narrowed
or completely closed. The vestibule is lined by modified skin, and contains hairs
(vibrissae) which guard the entrance of the nostril.
Structure of the Mucous Membrane (Fig. 724). — The epithelium covering the
mucous membrane differs in its character according to the functions of the part of
the nose in which it is found. In the respiratory portion of the nasal cavity the
epithelium is columnar and ciliated. Interspersed among the columnar ciliated
cells are goblet or mucin cells, while between their bases are found smaller pyra-
midal cells. In this region, beneath the epithelium and its basement membrane,
is a fibrous layer infiltrated with lymph-corpuscles, so as to form in many parts
mi
a diffuse adenoid tissue, which is particularly plentiful in children, and beneath
this a nearly continuous layer of smaller and larger glands, some mucous and some
serous, the ducts of which open upon the surface. In the respiratory portion of
the mucous membrane there is an extensive anastomosing plexus of veins, which
in some regions forms a distinct cavernous tissue (plexus cavernosus concharum).
The cavernous tissue is particularly distinct over the inferior turbinated bones.
In the olfactory region the mucous membrane is yellowish in color and the epi-
thelial cells are columnar and non-ciliated; they are of two kinds, supporting cells
and olfactory cells.
The Supporting Cells contain oval nuclei, situated in the deeper parts of the cells ;
the free surface of each cell presents a sharp, outline, and its deep extremity is
prolonged into a process which runs inward, branching to communicate with
similar processes from neighboring cells, so as to form a network in the deep part
of the mucous membrane. Lying between these central processes of the support-
ing cells are a large number of spindle-shaped cells, the olfactory cells, which con-
sist of a large spherical nucleus surrounded by a small amount of granular proto-
plasm, and possessing two processes, of which one runs outward between the
columnar epithelial cells, and projects on the surface of the mucous membrane
as a fine, hair-like process, the olfactory hair; the other or deep process runs inward,
is frequently beaded like a nerve-fibre, and is believed by most observers to be in
connection with one of the terminal filaments of the olfactory nerve. Beneath the
EPITHELIUM
NERVE
BUNDLESV _—
GLANDS OF
BOWMAN
NERVE
BUNDLES
FIG. 724. — Section of the olfactory mucous membrane. (Cadiat.)
epithelium, extending through the thickness of the mucous membrane, is a layer
of tubular,, often branched, glands, the glands of Bowman (glandulae olfactoriae) ,
identical in structure with serous glands.
The Arteries of the Nasal Fossae. — The arteries of the nasal fossae are the anterior
and posterior ethmoidal, from the ophthalmic, which supply the ethmoidal cells,
frontal sinuses, and roof of the nose; the spheno -palatine, from the internal maxil-
lary, which supplies the mucous membrane covering the spongy bones, the
meatuses, and septum; the inferior artery of the septum, from the superior
coronary of the facial; and the infraorbital and alveolar branches of the internal
maxillary, which supply the lining membrane of the antrum. The ramifications
of these vessels form a close, plexiform network, beneath and in the substance of
the mucous membrane.
The Veins of the Nasal Fossae. — The veins of the nasal fossae form a close, cav-
ernous-like network beneath the mucous membrane. This cavernous appearance
1112 THE ORGANS OF SPECIAL SENSE
is especially well marked over the lower part of the septum and over the middle
and inferior turbinated bones. Some of the veins pass, with those accompanying
the spheno-palatine artery, through the spheno-palatine foramen; and others,
through the alveolar branch, to join the facial vein; some accompany the eth-
moidal arteries, and terminate in the ophthalmic vein; and, lastly, a few com-
municate with the veins in the interior of the skull, through the foramina in the
cribriform plate of the ethmoid bone, and the foramen caecum.
The Lymphatics of the Nasal Fossae. — The lymphatics can be injected from the
subdural and subarachnoid spaces, and form a plexus in the superficial portion of
the mucous membrane. The lymph is drained partly into one or two glands which
lie near the great cornu of the hyoid bone and partly into a gland situated in front
of the axis.
The Nerves of the Nasal Fossae. — The nerves are: the olfactory, the nasal branch
of the ophthalmic, filaments from the anterior dental branch of the superior maxillary,
the Vidian, the naso-pala'tine, descending anterior palatine, and nasal branches
of Meckel's ganglion. The olfactory, the special nerve of the sense of smell, is
distributed to the olfactory region, and has been already referred to (p. 1019).
The nasal branch of the ophthalmic division of the trigeminal nerve distributes
filaments to the forepart of the septum and outer wall of the nasal fossae.
Filaments from the anterior dental branch of the superior maxillary supply the
inferior meatus and inferior turbinated bone. The Vidian nerve supplies the
upper and back part of the septum and superior spongy bone, and the upper
anterior nasal branches from the spheno-palatine ganglion have a similar distribution.
The naso-palatine nerve supplies the middle of the septum. The larger or
anterior palatine nerve supplies the lower nasal branches to the middle and lower
spongy bones.
Surgical Anatomy. — Instances of congenital deformity of the nose are occasionally met with,
such as complete absence of the nose, an aperture only being present; or perfect development
on one side, and suppression or malformation on the other; or there may be imperfect apposi-
tion of the nasal bones, so that the nose presents a median cleft or furrow. Deformities which
have been acquired are much more common, such as flattening of the nose (saddle nose), the result
of syphilitic necrosis, imperfect development of the nasal bones in cases of congenital syphilis, or
a lateral deviation of the nose the result of fracture.
The skin over the alae and tip of the nose is thick and closely adherent to subjacent parts.
Inflammation of this part is therefore very painful, on account of the tension. The skin is largely
supplied with blood, and, the circulation here being terminal, vascular engorgement is liable to
occur, especially in women at the menopause and in both sexes from disorders of digestion, exposure
to cold, etc. The skin of the nose also contains a large number of sebaceous follicles, and these, as
a result of intemperance, are apt to become affected, and the nose becomes reddened, congested,
and irregularly swollen. To this condition the term grog-blossom is popularly applied. In some
of these cases there is enormous hypertrophy of the skin and subcutaneous tissues, producing
pendulous masses, termed lipomata nasi. Ordinary epithelioma and rodent ulcer may attack
the nose, the latter being the more common of the two. Lupus and syphilitic ulceration fre-
quently attack the nose, and may destroy the whole of the cartilaginous portion. In fact, lupus
vulgaris begins more frequently on the ala of the nose than in any other situation.
Cases of congenital occlusion of one or both nostrils, or adhesion between the ala and septum
may occur, and may require immediate operation, since the obstruction much interferes with
sucking. Bony closure of the posterior nares may also occur.
To examine the nasal cavities, the head should be thrown back and the nose drawn upward,
the parts being dilated by some form of speculum. They can also be examined with the little finger
or a probe, and in this way foreign bodies detected. A still more extensive examination can be
made by Roux's operation, which was introduced for the cure of ozcena. This operation enables
the surgeon to remove any dead bone which may be present in this disease. The cartilaginous
framework of the nose is lifted up by an incision made inside the mouth, through the junction
of the upper lip with the bone; the septum nasi and the lateral cartilages are divided with strong
scissors till the anterior nares are completely exposed. The posterior nares can be explored by
the aid of reflected light from the mouth, by which the posterior nares can be illuminated. The
examination is very difficult to carry out, and, as a rule, sufficient information regarding the
THE EYE 1113
presence of foreign bodies or tumors in the naso-pharynx can be obtained by the introduction
of the finger behind the soft palate through the mouth. The septum of the nose may be dis-
placed or deviate from the middle line: this may be the result of an injury or from some con-
genital defect in its development; in the latter case the deviation usually occurs along the line
of union of the vomer and mesethmoid, and rarely occurs before the seventh year. Sometimes
the deviation may be so great that the septum may come in contact with the outer wall of the
nasal fossa, and may even become adherent to it, thus producing complete obstruction. Per-
foration of the septum is not an uncommon affection and may arise from several causes: syphilitic
or tuberculous ulceration, blood-tumor or abscess of the septum, and especially in workmen
exposed to the vapor of bichromate of potash, from the irritating and corrosive action of fumes.
\\hen small, the perforation may cause a peculiar whistling sound during respiration. When
large, it may lead to the falling in of the bridge of the nose.
Epistaxis is a very common affection in children. It is rarely of much consequence, and will
almost always subside, but in the more violent hemorrhages of later life it may be necessary
to plug the posterior nares. In performing this operation it is desirable to remember the size
of the posterior nares. A ready method of regulating the size of the plug to fit the opening
is to make it of the same size as the terminal phalanx of the thumb of the patient to be oper-
ated on.
.VrtA-o/ polypus is a very common disease, and presents itself in three forms: the gelatinous,
the fibrous, and the malignant. The first is by far the most common. It grows from the mucous
membrane of the outer wall of the nasal fossa, where there is an abundant layer of highly vas-
cular submucous tissue; rarely from the septum, where the mucous membrane is closely adher-
ent to the cartilage and bone, without the intervention of much, if any, submucous tissue. The
most common seat of gelatinous polyps is probably the middle turbinated bone. The fibrous
polypus generally grows from the base of the skull behind the posterior nares or from the roof
of the nasal fossae. The malignant polypi, both sarcomatous and carcinomatous, may arise
in the nasal cavities and the naso-pharynx; or they may originate in the antrum, and protrude
through its inner wall into the nasal fossa.
Rhinoliths or nose-stones may sometimes be found in the nasal cavities. They arise from
the deposition of phosphate of lime upon either a foreign body or a piece of inspissated secretion.
The nasal passages furnish a secretion of their own and receive secretion from other parts
(tears and secretions of the accessory sinuses). The nasal cavities contain the ethmoidal laby-
rinths, the lateral masses of the ethmoid (which form the superior and middle turbinated bones),
and the inferior turbinated bones. The nasal cavity is surrounded by three pairs of pneumatic
spaces, the accessory sinuses. These are the maxillary sinuses, the frontal sinuses, and the
cells of the ethmoidal labyrinth. The lachrymal duct opens into the inferior meatus. Inflam-
mation of the air-cells may follow inflammation of the nasal mucous membrane or bone disease.
One set of cells or many may suffer. Suppuration may occur. Pus may be blocked up and
retained. Dead bone may form. The most serious conditions may follow (abscess of brain,
sinus thrombosis, septicaemia), and an operation is necessary to obtain relief.
THE EYE.
The eyeball or globe (hulbus oculi) (Figs. 725 and 729) is contained in the ante-
rior part of the cavity of the orbit. In this situation it is securely protected from
injury, whilst its position is such as to ensure the most extensive range of sight.
It is acted upon by numerous muscles, by which it is capable of being directed
to different parts; it is supplied by vessels and nerves, and is additionally pro-
tected in front by the orbital margins, eyelids, etc.
The eyeball is embedded in the fat of the orbit, but is partly surrounded by
a thin membranous sac, the capsule of Te'non, which isolates it, so as to allow
of free movement.
The Fascia or Capsule of Te'non (fascia bulbi [Tenoni\) (Figs. 725 and
726). — The fascia or capsule of Tenon consists of a thin membrane which
envelops the eyeball from the optic nerve to the ciliary region, separating it from
the orbital fat and forming a socket in which it plays. Its inner surface is smooth,
and is in contact with the outer surface of the sclerotic, the perisclerotic or supra-
scleral lymph-space only intervening. This lymph-space is continuous with the
subdural and subarachnoid spaces, and is traversed by delicate bands of con-
1114
THE ORGANS OF SPECIAL SENSE
OPTIC NERVE-
CAPSULE
OF TENON
FIG. 725. — The right eye in sagittal section, showing the capsule of Tenon (semidiagrammatic). (Testut.)
nective tissue which extend between
the capsule and the sclerotic. This
lymph-space forms a flexible pocket,
in which the globe rotates. The cap-
sule of Tenon, with the globe, forms
a ball-and-socket joint (Deaver).
The capsule is perforated behind by
d the ciliaxy vessels and nerves and by
the optic nerve, being continuous with
the sheath of the latter. In front it
blends with the ocular conjunctiva,
and with it is attached to the ciliary
region of the eyeball. It is perforated
by the muscles which move the eye-
ball and on to each muscle it sends
a tubular sheath. The sheath of the
Superior oblique is carried as far as
FIG. 726-— The capsule of T<5non. The aponeurosis is the fibroUS pulley of that muscle: that
seen from behind forward on the posterior hemisphere of i • <• • i i« f
theglobe:a,cellulo-nbrousintermuscular laminae; b, deep On the interior ObllOUe reaches as tar
leaf of the sheath incised at the point where it leaves the , i n t , i i • , i • i • ,
muscle to fold itself on the posterior hemisphere when as the IlOOr Ot the Orbit, tO WhlCll it
it forms the posterior capsule; d, partly incised; c, serous •„„ ^flp „ !• T*U^ ^U^+l™ , +U«
membrane. (Poirier and Charpy.) glVCS On a Slip. 1 he Sheaths On the
recti are gradually lost in the peri-
mysium, but they give off important expansions. The expansion from the
Superior rectus blends with the tendon of the Levator palpebrae; that of the
Inferior rectus is attached to the inferior tarsal plate. These two recti, therefore,
will exercise some influence on the movements of the eyelids. The expansions
THE EYE
1115
from the sheaths of the Internal and External recti are strong, especially the one
from the latter muscle, and are attached to the lachrymal and malar bones respec-
tively. As they probably check the action of these two recti, they have been
named the internal and external check ligaments.
Lockwood has also described a thickening of the lower part of the capsule of
Tenon, which he has named the suspensory ligament of the eye. It is slung like a
hammock below the eyeball, being expanded in the centre and narrow at its
extremities, which are attached to the malar and lachrymal bones respectively.1
The anterior one-third of the globe is covered by the conjunctiva, or mucous
membrane, reflected from the inner surfaces of the lids (Fig. 728). A lateral view
POSTERIOR CHAMBER
OF EYE
CILIARY
PROCESS
PARS CILIARIS
RETINAE
ORA SERRATA
PARS OPTIC A
RETINJE
SCLEROTIC
YELLOW
SPOT
OPTIC
EXCAVATION
FIG. 727. — The right eye iix horizontal section. (Toldt.)
of the globe shows that it is composed of segments of two spheres of different sizes
(Figs. 725, 727, 728, and 729). The anterior segment is one of a small sphere, and
forms about one-sixth of the eyeball. It is more prominent than the posterior seg-
ment, which is one of a much larger sphere, and forms about five-sixths of the globe.
The segment of the larger sphere is opaque, and formed by the sclerotic, the tunic
of protection to the eyeball ; the smaller sphere is transparent, and formed by the
cornea. Between the small, anterior or corneal segment, and the large, posterior
or scleral segment, is a shallow and narrow groove, the scleral sulcus (sulcus sclerae).
The anterior pole is the centre of the anterior portion of the cornea. The posterior
pole is the centre of the posterior portion of the sclerotic. A straight line joining
these two poles is the sagittal or optic axis (axis optica) (Fig. 727). A line drawn
around the eyeball equally distant at all points from the two poles is called the
1 See a paper by C. B. Lockwood, Journal of Anatomy and Physiology, vol. xx., part i., p. 1. — ED of 15th
English edition.
1116
THE ORGANS OF SPECIAL SENSE
equatorial diameter or the equator (Fig. 727). The plane of the equator divides
the globe in an anterior and a posterior hemisphere. Meridians may be drawn from
one pole to the other at right angles to the equator. The visual axis (linea visus)
(Fig. 727) passes in a straight line from the first nodal point on the cornea to the
fovea centralis of the yellow spot on the retina. A nodal point is the point of inter-
section of convergent rays with the visual axis. The first nodal point is 6.9685 mm.
FIG. 728. — Diagram of a horizontal section of the right eye, showing the upper surface of the lower
segment. (Testut.)
behind the summit of the cornea. The axes of the eyeballs are nearly parallel,
and therefore do not correspond to the axes of the orbits, which are directed
outward. The optic nerves follow the direction of the axes of the orbits, and
are therefore not parallel; each nerve enters its eyeball about 1 mm. below and
3 mm. to the inner or nasal side of the posterior pole (Fig. 727). The eyeball
measures rather more in its transverse and antero-posteror diameters than in its
vertical diameter, the former amounting to nearly an inch, the latter to about
nine-tenths of an inch. The diameters in the female are somewhat less than
in the male.
The eyeball is composed of three investing tunics and of three refracting media.
THE SCLERA
1117
THE TUNICS OF THE EYE.
From without inward the three tunics are:
I. Sclerotic Coat and Cornea.
II. Choroid, Ciliary Body, and Iris.
III. Retina.
I. The Fibrous or External Coat: The Sclerotic and Cornea
(Tunica Fibrosa Oculi).
The sclerotic and cornea (Figs. 727, 728, and 729) form the external tunic of
the eyeball; they are essentially fibrous in structure, the sclerotic being opaque,
and forming the posterior five-sixths of the globe; the cornea, which forms the
remaining sixth, being transparent.
The Sclera or Sclerotic Coat (axXypbs, hard).— The sclera or sclerotic coat
has received its name from its extreme density and hardness; it is a firm, unyield-
ing, opaque, fibrous membrane, forming the posterior five-sixths of the outer coat
Canal of Schlemm.
Posterior
chamber.
Ciliary
Cavity occupied
by vitreous humor
Retina.
Choroid
coat.
Sclerotic coat.
Nerve sheath.
Canal for
"central artery.
Optic nerve.
FIG. 729. — A horizontal section of the eyeball. (Allen.)
and serving to maintain the form of the globe. It is much thicker behind than in
front. Its external surface is of a white color, and is in contact with the inner
surface of the capsule of Tenon, a lymph-space intervening; it is quite smooth,
except one-quarter of an inch back of the sclero-corneal junction, at the points
where the Recti and Obliqui muscles are inserted into it, and its anterior part is
covered by the conjunctival membrane (Fig. 757); hence the whiteness and bril-
liancy of the front of the eyeball. Its inner surface is stained a brown color, marked
by grooves, in which are lodged the ciliary nerves and vessels (Figs. 732, 737, and
738) ; the inner surface of the sclera is loosely connected by three layers of exceed-
1118 THE ORGANS OF SPECIAL SENSE
ingly fine cellular pigmented tissue (lamina fusca) with the outer surface of the
choroicl, an extensive lymph-space, the perichoroidal space (spatium perichorioideale)
(Figs. 740 and 757) intervening between the sclerotic and choroid. Behind, the
sclera is pierced by the optic nevre (n. opticus), and is continuous with the fibrous
sheath of the nerve, which is derived from the dura (Fig. 734). At the point where
the optic nerve passes through the sclerotic, the lamina fusca is represented by an
arrangement of the fibrous tissue which forms a thin network, the cribriform lamina
(lamina cribrosa sclerae) (Fig. 744) ; the minute orifices in this network serve for the
transmission of separate bundles of nervous filaments, and the fibrous septa divid-
ing them from one another are continuous with the membranous processes which
separate the bundles of nerve-fibres. One of these openings (porus opticus), larger
than the rest, occupies the centre of the lamella; it transmits the arteria centralis
retinae to the interior of the eyeball (Fig. 744). Around the cribriform lamella are
numerous small apertures for the transmission of the ciliary nerves and the short
ciliary arteries, and about midway between the margin of the cornea and the
entrance of the optic nerve are four or five large apertures, for the transmission of
veins (venae vorticosae) (Fig. 757). In front, the fibrous tissue of the sclerotic is con-
tinuous with the substantia propria of the cornea by direct continuity of tissue (Fig.
757), but the opaque sclerotic slightly overlaps the outer surface of the transparent
cornea. In the depths of the line of junction between the cornea and the sclera
there is a circular canal, the canal of Schlemm (sinus venosus sclerae) (Figs. 729, 736,
740, and 757). This canal receives the sclera veins (Fig. 736) and communicates
internally by numerous minute openings in the pectineal ligament of the iris (Fig.
757) with the anterior chamber of the eyeball. These openings are the spaces of
Fontana (Fig. 740).
Structure. — The sclerotic is formed of white fibrous tissue intermixed with fine
elastic fibres, and of flattened connective-tissue corpuscles, some of which are pig-
mented, contained in cell-spaces between the fibres (Figs. 733 and 744). These
fibres are aggregated into bundles, some of which are arranged in layers having an
equatorial direction, but most of which are arranged in layers lying in meridian
lines. The sclera is joined to the choroid by three thin layers of loose connective
tissue containing pigment cells, the lamina fusca (lamina fasciae sclerae) (Fig. 737).
Where the optic nerve passes through the sclera there is very thin network to repre-
sent the lamina fusca. This network is the lamina cribrosa (Fig. 744). The muscles
of the eyeball are attached to the sclera (Figs. 728, 729, and 757), and their tendons
enter among the bundles of fibrous connective tissue. The conjunctiva covers the
anterior portion of the sclera and is attached to it by submucous tissue (Figs. 728
and 740). The sclera yields gelatin on boiling. Its vessels (Figs. 734 and 736) are
not numerous, the capillaries being of small size and uniting at long and wide inter-
vals. It obtains arterial blood from the short posterior ciliary and the anterior ciliary
arteries. The venous blood is removed by the venae vorticosae and the anterior ciliary
veins. There are lymph-spaces between the cells which empty into the periscleral
(Fig. 725 and p. 1114) and perichoroidal lymph-spaces (Fig. 740). Its nerves are
derived from the ciliary nerves (Fig. 732). They lose their medullary sheaths and
enter among the bundles of fibrous tissue, but it is not known how they terminate.
The Cornea (Figs. 725, 728, and 734). — The cornea is the projecting transparent
part of the external tunic of the eyeball, and forms the anterior sixth of the globe. It
is almost, but not quite, circular in shape, occasionally a little broader in the trans-
verse than in the vertical direction. It is convex anteriorly, and projects forward
from the sclerotic in the same manner that a watch-glass does from the case. Its
degree of curvature varies in different individuals, and in the same individual at dif-
ferent periods of life, it being more prominent in youth than in advanced life, when
it becomes flattened. Usually the curvature is slightly greater in the vertical plane
than in the horizontal plane; at its centre than at its periphery, and at its temporal
than at its nasal side. The cornea is dense and of uniform thickness throughout;
THE CORNEA
1119
its posterior surface is perfectly circular in outline, and exceeds the anterior sur-
face slightly in extent, from the latter being overlapped by the sclerotic. The
anterior surface is covered with conjunctiva (Fig. 740).
Structure (Fig. 730). — The cornea consists of five layers — namely: (1) the anterior
or epithelial layer; (2) the anterior elastic layer; (3) the substantia propria; (4)
the posterior elastic layer; (5) the posterior or endothelial layer.
Anterior
epithelium
^Substantia
' propria
-Posterior
epithelium
FIG 730. — Vertical section through the cornea of a newborn child. X 200. (Szymonowicz.)
(1) The Anterior Layer (epithelium corneae] is composed of stratified epithelium
and is continuous with the cells of the conjunctiva at the borders of the cornea.
There are from five to eight strata of nucleated cells in the anterior layer. The
deepest cells are columnar. Above the columnar cells are several layers of
polygonal cells, most of which have finger-like processes and are called prickle
cells. At the surface the cells and nuclei become flat. The anterior epithelial
layer prevents the absorption of the fluid of the tears.
(2) The Anterior Elastic or Anterior Limiting Layer or Bowman's Membrane (lamina
elastica anterior) is less than half the thickness of the layer of stratified epithelium.
1120
THE ORGANS OF SPECIAL SENSE
It differs in some essential respects from true elastic tissue. It shows evidences
of fibrillary structure, and does not have a tendency to curl inward or to undergo
fracture when detached from the other layers of the cornea. It consists of ex-
tremely close interwoven fibrils, similar to those found in the rest of the cornea
proper, but contains no corneal corpuscles. It ought, therefore, to be regarded
as a part of the proper tissue of the cornea*
(3) The Substantia Propria or proper substance of the cornea forms the main
thickness of that structure. It is fibrous, tough, unyielding, perfectly transparent,
and continuous with the sclerotic. It is composed of about sixty flattened lamellae,
superimposed one on another. These lamellae are made up of bundles of modified
connective tissue, the fibres of which are directly continuous with the fibres of the
sclerotic. The fibres of each lamella are for the most part parallel with each
other; those of alternating lamellae at right angles to each other. Fibres, however,
frequently pass obliquely from one lamella to the next (fibrae arcuatae).
The lamellae are connected with each other by an interstitial cement-substance,
in which are spaces, the corneal spaces, cell spaces or lacunae (Fig. 731). The
spaces are stellate in shape, and have numerous offsets or canaliculi (Fig. 731),
by which they communicate with each other. Each space contains a cell, the
corneal corpuscle (Fig. 731), which resembles in form the space in which it is
Lymph canaliculi
Corneal cell in
lymph space
FIG. 731. — From a horizontal section of an ox's cornea. Positive picture of the canal system demonstrated
by the gold chloride method. X 450. (Szymonowicz.)
lodged, but it does not entirely fill it, the remainder of the space containing
lymph. In the aged the margin of the cornea becomes opaque gray. This rim
is called the arcus senilis, and is due to fat deposit in the lamellae and corneal
corpuscles.
(4) The Posterior Elastic Lamina, the Membrane of Descemet, or the Membrane
of Demours (lamina elastica posterior], which covers the proper structure of the
cornea behind, presents no structure recognizable under the microscope. It
consists of an elastic, and perfectly transparent homogeneous membrane, of
extreme thinness, which is not rendered opaque by either water, alcohol, or acids.
It is very brittle, but its most remarkable property is its extreme elasticity, and
the tendency which it presents to curl up, or roll upon itself, with the attached
surface innermost, when separated from the proper substance of the cornea. Its
use appears to be (as suggested by Dr. Jacob) "to preserve the requisite perma-
nent correct curvature of the flaccid cornea proper."
At the margin of the cornea this posterior elastic membrane breaks up into fibres
to form a reticular structure at the outer angle of the anterior chamber, the intervals
between the fibres forming small cavernous spaces, the spaces of Fontana (spatia
THE CHOROID 1121
anguli iridis) (Fig. 740). These little recesses communicate with a circular canal
in the deeper parts of the corneo-scleral junction. This is the canal of Schlemm
(Figs. 729, 736, and 740); it communicates internally with the anterior chamber
through the spaces of Fontana, and externally with the scleral veins. Some of the
fibres of this reticulated structure are continued into the front of the iris, forming
the ligamentum pectinatum iridis; while others are connected with the forepart of
the sclerotic and choroid.
(5) The Posterior Layer or the Cornea! Endothelium (endothelium camerae ante-
riorift) lines the aqueous chamber and prevents the absorption of the aqueous
humor. It covers the posterior surface of the elastic lamina, is reflected on to
the front of the iris, and also lines the spaces of Fontana. It consists of a single
layer of polygonal flattened transparent nucleated cells, similar to those lining
other serous cavities.
Arteries and Nerves. — The foetal cornea contains blood-vessels which pass from
the margin almost to the centre. The adult cornea contains no blood-vessels,
except at its margin. The capillaries from the 'solera and conjunctiva form loops
at the corneal margin, and many of these loops enter the cornea for a distance of
1 mm. (Fig. 736). The balance of the cornea is non-vascular and obtains its
nourishment from the lymph in the lacunae and canaliculi. Lymphatic vessels
have not as yet been demonstrated in it, but are represented by the channels in
which the bundles of nerves run; these channels are lined by endothelium and are
continuous with the cell-spaces. The nerves are numerous, twenty-four to thirty-
six in number (Kolliker), forty to forty-five (Waldeyer and Siimisch); they are
derived from the ciliary nerves; they form the annular plexus (plexus annularis),
at the corneal margin, and enter the laminated tissue of the cornea, lose their
medullary sheaths, and ramify throughout the substantia propria as the funda-
mental plexus or the plexus of the stroma. From this deep plexus come perforating
fibres (fibrae perforantes) , which pass through the anterior elastic lamina and form
the subepithelial plexus, and from it fibrils are given off which ramify between
the epithelial cells, forming a network which is termed the intra-epithelial plexus.
Nerve-fibres from the annular plexus and from the plexus of the stroma come
into close relation with the corneal corpuscles.
Dissection. — In order to separate the sclerotic and cornea, so as to expose the second tunic,
the eyeball should be immersed in a small vessel of water and held between the finger and thumb.
The sclerotic is then carefully incised, in the equator of the globe, till the choroid is exposed.
One blade of a pair of probe-pointed scissors is now introduced through the opening thus made,
and the sclerotic divided around its entire circumference, and removed in separate portions.
The front segment being then drawn forward, the handle of the scalpel should be pressed gently
against it at its connection with the iris, and, these being separated, a quantity of perfectly trans-
parent fluid will escape; this is the aqueous humor. In the course of the dissection the ciliary
nerves (Fig. 732) may be seen lying in the loose cellular tissue between the choroid and sclerotic
or continued in delicate grooves on the inner surface of the latter membrane.
II. The Choroid, Ciliary Body, and Iris, the Tunica Media, the Uveal Tract
(Tunica Vasculosa Oculi) (Figs. 727, 729, 732, 737, 757).
The second or middle tunic of the eye is formed from behind forward by the
choroid, the ciliary body, and the iris.
The choroid is the vascular and pigmentary tunic of the eyeball, investing the
posterior five-sixths of the globe, and extending as far forward as the ora serrata
of the retina; the ciliary body connects the choroid to the circumference of the
iris. The iris is the circular muscular septum, which hangs vertically behind the
cornea, presenting in its centre a large rounded aperture, the pupil.
The Choroid (chorioidea). — The choroid is a thin, highly vascular membrane,
of a dark-brown or chocolate color, which invests the posterior five-sixths of the
71
1122
THE ORGANS OF SPECIAL SENSE
globe, and is pierced behind by the optic nerve, and in this situation is firmly
adherent to the sclerotic. It is thicker behind than in front. Externally, it is
loosely connected by the lamina
fusca with the inner surface of the
sclerotic (p. 1118). Its inner sur-
face is attached to the retina.
Structure (Fig. 733) .— The choroid
consists of a dense capillary plexus
and of small arteries and veins,
carrying the blood to and returning
it from this plexus (Fig. 736), and of
branched and pigmented cells which
lie in connective tissue. There are
three layers in the choroid. Named
from without inward, they are the
lamina suprachorioidea, the choroid
proper, and lamina basalis (Fig. 733) .
(1) The Lamina Suprachorioidea
is on the external surface, that is,
the surface next to the sclerotic.
It resembles the lamina fusca of
the sclerotic. It is composed of
delicate non-vascular lamellae, each
lamella consisting of a network of
fine elastic fibres, among which are
branched pigment-cells. The spaces
between the lamellae are lined by
endothelium, and open freely into the perichoroidal lymph-space, which, in its
turn, communicates with the periscleral space by the perforations in the sclerotic
through which the vessels and nerves are transmitted.
(2) The Choroid Proper is internal to the lamina suprachorioidea. In consequence
of the small arteries and veins of the choroid proper being arranged on the outer
surface of the capillary network, it is customary to describe this as consisting of
two layers: the outermost (lamina vasculosa), composed of small arteries and
FIG. 732.— The choroid and iris. (Enlarged.)
Pigment layer
of retina
Lamina
basalts'
Lamina
chorio-
capillaris
Lamina
vasculosa
Lamina supra-
chorioidea
Part of the
sdera
FIG. 733.— Vertical section through the chorioidea and a part of the sclera of an ape. X 440. (Szymonowicz.)
veins, with pigment-cells interspersed between them, and the inner (lamina
choriocapillaris) , consisting of a capillary plexus. The external layer of the choroid
proper or the lamina vasculosa consists, in part, of the larger branches of the short
THE CHOROID
1123
posterior ciliary arteries (Figs. 734, 736, and 738). which run forward between the
veins, before they bend inward to terminate in the capillaries; but this layer is
VENA
VORTICOSA
ANTERIOR
•S CILIARY
I ARTERY
-SCLEROTIC
SHORT
POSTERIOR
CILIARY
ARTERIES
LONG POSTERIOR
CILIARY ARTERY
FIG. 734. — Vessels and nerves of the choroid and iris, seen from above. The sclerotic and cornea have
been largely removed. (Testut.)
formed principally of veins, which have a whirl-like arrangement and empty into
four or five large equidistant trunks, the venae vorticosae (Figs. 734, 735, and 736),
which pierce the sclerotic midway
between the margin of the cornea
and the entrance of the optic
nerve. Around the veins are
lymph-spaces. Interspersed be-
tween the vessels are dark star-
shaped pigment-cells, the offsets
from which, communicating with
similar branchings from neigh-
boring cells, form a delicate net-
work or stroma, which toward
the inner surface of the choroid
loses its pigmentary chraacter.
The internal layer of the choroid
proper consists of an exceedingly
fine capillary plexus, formed by
the short ciliary vessels (Fig. 736),
and is known as the tunic Of FIG. 735.— The veins of the choroid. (Enlarged.)
Ruysch (lamina choriocapillaris) .
The network is close, and finer at the hinder part of the choroid than in front.
About half an inch behind the cornea its meshes become larger, and are continuous
1124
THE ORGANS OF SPECIAL SENSE
with those of the ciliary processes. These two laminae are connected by an interme-
diate stratum, which is destitute of pigment-cells and consists of fine elastic fibres.
On the inner surface of the lamina choriocapillaris is a very thin, structureless,
or, according to Kolliker, faintly fibrous membrane, called the lamina basalis
or membrane of Bruch; it is closely connected with the stroma of the choroid, and
separates it from the pigmentary layer of the retina.
Oornea-U
Iris
Lens
FIG. 736. — Diagram of the blood-vessels of the eye, as seen in a horizontal section. (Leber, after Stohr.)
, . .
Course of vasa centralia retinae: a, arteria, ai vena centralis retinae; /?, anastomosis with vessels of outer
coats; 7, anastomosis with branches of short posterior ciliary arteries; (J, anastomosis with chorioideal vessels.
Course of vasa ciliar. postic. brev. : I, arteriae, and Ij, venae ciliar. postic. brev.; II, episcleral artery;
III, episcleral vein; III, capillaries of lamina choriocapillaris.
Course of vasa ciliar. postic. long.: 1, a. ciliar. post, longa; 2, circulus iridis major cut across; 3, branches to
ciliarv bodv: 4. branches to iris.
Tapetum (lucidum). — This name is applied to the iridescent appearance which
is seen in the outer and posterior parts of the choroid of many animals, but not
in man.
The ciliary body should now be examined. It may be exposed, either by detaching the iris
from its connection with the Ciliary muscle, or by making a transverse section of the globe, and
examining it from behind.
THE CILIARY BODY
1125
ANNULUS
ILIARIS
ORBICULUS
CILIARIS
POSTERIOR
SMOOTH
PORTION
OF CHOROID
INNER
SURFACE
OF SCLERA
The Ciliary Body (corpus ciliare) (Fig. 729). — The ciliary body or cyclon joins
the choroid to the margin of the iris. It is in reality a process of the choroid
or uveal tract and comprises the orbiculus ciliaris, the ciliary processes, and the
Ciliary muscle.
•The Orbiculus Ciliaris or Annulus Ciliaris (Figs. 737, 739, and 755). — The
orbiculus ciliaris is a zone of about one-sixth of an inch in width, directly con-
tinuous with the anterior part of the choroid. The lamina basalis presents numer-
ous ridges arranged in a radial manner. The depressions between the ridges
are filled with retinal pigment epithelium (Szymonowicz). The orbiculus contains
no lamina choriocapillaris.
The Ciliary Processes (processus ciliares) (Figs. 727, 729, 739, and 757). — The
ciliary processes are formed by the plaiting and folding inward of the various
layers of the choroid — i. e., the choroid proper and the lamina basalis — at its
anterior margin, and are received between corresponding foldings of the suspen-
sory ligament of the lens, thus establishing a connection between the choroid and
inner tunic of the eye. They are arranged in a circle, and form a sort of plaited
frill, the corona ciliaris, behind the iris,
round the margin of the lens (Figs. 739
and 757). They vary between sixty and
eighty in number, lie side by side, and
may be divided into large and small;
the latter, consisting of about one-third
of the entire number, are situated in the
spaces between the former, but without
regular alternation. The larger processes
are each about one-tenth of an inch in
length, and are attached by their per-
iphery to three or four of the ridges of
the orbiculus ciliaris, and are continu-
ous with the layers of the choroid; the
opposite margin is free, and rests upon
the circumference of the lens. Their
anterior surface is turned toward the
back of the iris, with the circumference of which they are continuous,
posterior surface is connected with the suspensory ligament of the lens.
Structure. — The ciliary processes are similar in structure to the choroid, but the
vessels are larger, and have chiefly a longitudinal direction. They are the most
vascular portion of the eyeball. The processes are covered on their inner surface
by two strata of black pigment-cells, which are continued forward from the retina,
and are named the pars ciliaris retinae (Figs. 733 and 740). In the stroma of the
ciliary processes there are also stellate pigment-cells, which, however, are not so
numerous as in the choroid itself.
The Ciliary Muscle or Bowman's Muscle (m. ciliaris} (Figs. 732, 734, 738,
740, 741, and 742). — The ciliary muscle consists of unstriped fibres; it forms
a grayish, semitransparent, circular band, about one-eighth of an inch broad,
on the outer surface of the forepart of the choroid, between the choroid and
the iris and back of the sclero-corneal junction. It is thickest in front and
gradually becomes thinner behind. It consists of two sets of fibres, radiating and
circular.
The Radiating Fibres (fibrae meridianales [Bruckei]) (Figs. 740 and 757), much
the more numerous, arise at the point of junction of the cornea and sclerotic, and
partly also from the ligamentum pectinatum iridis, and, passing backward, are
attached to the choroid opposite to the ciliary processes. One bundle, according
to Waldeyer, is continued backward to be inserted into the sclerotic.
CORNEA (POS
tenor surface)
FIG. 737. — The middle or vascular coat of the eyeball
exposed from without. Left eye, seen obliquely from
above and before. (Toldt.)
The
1126
THE ORGANS OF SPECIAL SENSE
The Circular Fibres (fibrae circulares [Mulleri]} (Figs. 740 and 757) are internal to
the radiating ones and to some extent unconnected with them, and have a circular
course around the attachment of the iris. They are sometimes called the "ring
muscle" of Muller, and were formerly described as the ciliary ligament. They are
well developed in hypermetropic, but are rudimentary or absent in myopic eyes.
Anterior ciliary artery.
Short ciliary arteries.
interior ciliary artery.
FIG. 738. — The arteries of the choroid and iris. The sclerotic has been mostly removed. (Enlarged.)
The Ciliary muscle is admitted to be the chief agent in accommodation — i. e., in
adjusting the eye to the vision of near objects. Bowman believed that this was
effected by its compressing the vitreous body, and so causing the lens to advance.
At the present time all agree that the chief element in accommodation is altered
curvature of the lens, but there is diversity of opinion as to the manner in which
ORBICULARIS
CILIARIS
CILIARY
PROCESSES
RIS (poste-
ior surface)
EQUATOR
OF LENS
LENS
W:-- ^^-.-,.
FIG. 739. — A portion of the corona ciliaris magnified. The ciliary processes and the ciliary folds. (Toldt.)
this is accomplished. The view which now prevails is that of Helmholtz. He
maintained that in an unaccommodated eye the capsule and suspensory ligament
of the lens are tense, and their pressure flattens the anterior surface of the lens,
and parallel rays (and rays from objects far off are practically parallel) "are
focused on the retina without any sense of effort."1
" In accommodation for a near object the meridional or antero-posterior fibres
1 Stewart, Manual of Physiology.
THE IRIS
1127
of the ciliary muscle by their contraction pull forward the choroid and relax the
suspensory ligament. The elasticity of the lens at once causes it to bulge forward
till it is again checked by the tension of the capsule."1 The pupil is at the same
time slightly contracted.
The Iris (iris, a rainbow) (Figs 729, 732, 734, 736, 737, 740, 741, 742, 743, and
757). — The iris has received its name from its various colors in different individ-
uals. It is a thin, circular-shaped, contractile curtain, suspended in the aqueous
humor behind the cornea, and in front of the lens, being perforated a little to the
nasal side of its centre by a circular aperture, the pupil (pupilla) (Fig. 743), for
the transmission of light. The pupil of a living person varies in size under the
influence of light and in efforts at accommodation. In looking at a near object the
pupil is small ; in looking at a distant object it is large. In light the pupil contracts,
in darkness it dilates; hence the pupil is a window which permits light to pass into
the interior of the eye. The size of this window depends on the contraction or
relaxation of the iris. The iris divides the aqueous chamber (the space between
Circ. fibres
of sclerotic.
Circ. fibres /
of Ciliary muscle.
Radiating
fibres of
Ciliary muscle.
( Pars ciliaris
\ retinas.
•^^S'
PIG. 740. — Section of the eye, showing the relations of the cornea, sclerotic, and iris, together with the Ciliary
muscle and the cavernous spaces near the angle of the anterior chamber. (Waldeyer.)
the cornea and lens) into an anterior chamber and a posterior chamber which com-
municate through the pupil (Figs. 727 and 729). By its circumference or ciliary mar-
gin (margo ciliaris) (Figs. 740 and 741) the iris is continuous with the ciliary body,
and it is also connected with the posterior elastic lamina of the cornea by means of
the pectinate ligament (ligamentum pectinatum iridis] (Fig. 757). The pectinate
ligament of the iris is derived from the posterior elastic layer of the cornea. This
layer divides into numerous fibrillae, and some of them reach the iris and bridge
the angle between the cornea and base of the iris (Deaver). The fibrillae which
reach the iris constitute the ligament. In this ligament are numerous lymph-
spaces, the spaces of Fontana (spatia anguli iridis [Fontanae]) (Fig. 740), and
they join the canal of Schlemm to the anterior chamber of the eye. The inner or
free edge of the iris forms the margin of the pupil, and is called the pupillary
margin (margo pupillaris) (Fig. 741). The surfaces of the iris are flattened, and
1 Stewart, Manual of Physiology.
1128
THE ORGANS OF SPECIAL SENSE
look forward and backward, the anterior toward the cornea, the posterior toward
the ciliary processes and lens. The iris is pigmented and the color of an individual's
eyes depends upon this pigment. The anterior surface (fades anterior} (Figs. 741
and 757) of the iris is variously colored in different individuals, and is marked by
lines which converge toward the pupil. The posterior surface (fades posterior) (Figs.
739 and 757) is of a deep-purple tint, from being covered by two layers of pig-
mented, columnar epithelium, which layers are continuous posteriorly with the
pars ciliaris retinae. This pigmented epithelium is termed the pars iridica retinae,
though it is sometimes named uvea, from its resemblance in color to a ripe grape.
Structure. — The iris is composed of the following structures:
1. In front is a layer of flattened endothelial cells placed on a delicate hyaline
basement-membrane. This layer is continuous with the endothelial layer covering
the membrane of Descemet, and in men with dark-colored irides the cells contain
pigment-granules.
2. Stroma (stroma iridis). — The stroma consists of fibres and cells. The former
are made of fine, delicate bundles of fibrous tissue, of which some few fibres have
CILIARY GANGLIATEO
PLEXUS
CILIARY MARGIN
OF IRIS
CILIARY
iPirMuscLE
ATTACHED
REMNANT OF
CORNEAL
MARGIN
STROMA
OF IRIS
CILIARY ZONE
OF
TRACTINGS
LDS OF IRIS
VASCULAR
NENCES
GMENT-CELL
PUPILLARY
OF
FREE BORDER
'OF PIGMENTARY
LAYER
FIG 741. — Section of the iris. Anterior surface magnified. (Toldt.)
PUPILLARY
MARGIN
a circular direction at the circumference of the iris, but the chief mass consists of
fibres radiating toward the pupil. They form, by their interlacement, a delicate
mesh, in which the vessels and nerves are contained. Interspersed between the
bundles of connective tissue are numerous branched cells with fine processes.
Many of them in dark eyes contain pigment-granules, but in blue eyes and the
pink eyes of albinos they are unpigmented.
3. The Muscular Fibre is involuntary and consists of circular and radiating
fibres. The circular fibres (m. sphincter pupillae) surround the margin of the pupil
on the posterior surface of the iris, like a sphincter, forming a narrow band about
one-thirtieth of an inch in width, those near the free margin being closely aggre-
gated ; those more external somewhat separated, and forming less complete circles.
The radiating fibres (TO. dilator pupillae) converge from the circumference toward
the centre, and blend with the circular fibres near the margin of the pupil. These
fibres are regarded by some as elastic, not muscular, but Grunnert positively
demonstrated them.1 The fibres are very small and are placed between the
stroma and the posterior layer of endothelium.
i Von Graefe's Arch. f. Ophthal., Bd. xlvii.
THE IRIS
1129
4. Pigment. — The situation of the pigment-cells differs in different irides. In
the various shades of blue eyes the only pigment-cells are several layers of small
round or polyhedral cells filled with dark pigment, situated on the posterior surface
CILIARY
MUSCLE
CILIARY
GANGLIATCD
PLEXUS
POSTER
LONG CILI,
ARTERY
ANTERIOR RADICLES
'OF ONE OF THE
VORTICOSE VEINS
II •IIIIBIIillBfc
FIG. 742. — The ciliary gangliated plexus and the ciliary nerves entering the plexus. Outer surface of the
middle or vascular coat of the eyeball. (Toldt.)
of the iris and continuous with the pigmentary lining of the ciliary processes. The
color of the eye in these individuals is due to this coloring-matter showing more
or less through the texture of the iris. 'In the albino even this pigment is absent.
ANTERIOR CILIARY ARTERIES
LONG CILIARY
ARTERY
ANTERIOR CILIARY ARTERIES
FIG. 743.— Iris, front view. (Testut.)
In the gray, brown, and black eye there are, as mentioned above, pigment-granules
to be found in the cells of the stroma and in the endothelial layers on the front of
the iris; to these the dark color of the eve is due.
1130 THE ORGANS OF SPECIAL SENSE
The Arteries of the Iris (Figs. 736, 738, 740, and 743).— The arteries of the iris are
derived from the long posterior ciliary and anterior ciliary and from the vessels of the
ciliary processes (see p. 1125). The long posterior ciliary arteries (Figs. 734 and 736),
two in number, pass through the sclera, one on the inner and one on the outer side
of the optic nerve, and pass forward between the sclera and choroid, and, having
reached the attached margin of the iris (Figs. 734 and 743), divide into an upper and
a lower branch, and, encircling the iris, anastomose with corresponding branches
from the opposite side; into this vascular zone (circulus arteriosus major) (Fig. 757)
the anterior ciliary arteries (Fig. 757), from the lachrymal and anterior ciliary from the
muscular branches of the ophthalmic, pour their blood. From this zone vessels con-J
verge to the free margin of the iris, and these communicate by branches from one
to another and thus form a second zone (circulus arteriosus minor) in this situation.
The veins pass toward the ciliary margin and communicate with the veins of the
ciliary processes and of the canal of Schlemm (Figs. 734 and 736).
The Nerves of the Choroid and Iris (Fig. 732). — The nerves of the choroid and
iris are the short ciliary, the ciliary branches of the lenticular ganglion, and the long
ciliary from the nasal branch of the ophthalmic division of the trigeminal. They
pierce the sclerotic around the entrance of the optic nerve, and run forward in the
perichoroidal lymph-space in which they form a plexus, from which plexus fila-
ments pass to supply the blood-vessels of the choroid. After reaching the iris they
form a plexus around its attached margin; from this are derived amyelinic fibres
which terminate in the circular and radiating muscular fibres. Their exact mode
of termination has not been ascertained. Other fibres from the plexus terminate
in a network on the anterior surface of the iris. The fibres derived from the motor
root of the lenticular ganglion (oculomotor nerve) supply the circular fibres, while
those derived from the sympathetic supply the radiating fibres.
Membrana Pupillaris. — In the foetus the pupil is closed by a delicate transparent
vascular membrane, the membrana pupillaris, which divides the space into which
the iris is suspended into two distinct chambers. This membrane contains numer-
ous minute vessels, continued from the margin of the iris to those on the front part
of the capsule of the lens. These vessels have a looped arrangement, and converge
toward each other without anastomosing. Between the seventh and eighth months
the membrane begins to disappear, by gradual absorption from the centre toward
the circumference, and at birth only a few fragments remain. It is said some-
times to remain permanent and produce blindness.
III. The Tunica Interna or Retina (Figs. 736, 744, 746).
The retina is a delicate nerve membrane, in which the fibres of the optic nerve
are spread out and upon the surface of which the images of external objects are
received. Its outer surface is in contact with the choroid ; its inner with the vitreous
body. Behind, it is continuous with the optic nerve; it gradually diminishes in
thickness from behind forward; and, in front, extends nearly as far as the ciliary
body, where it appears to terminate in a jagged margin, the ora serrata (Figs. 736,
745, and 757). Here the nerve tissues of the retina end, but a thin prolongation
of the membrane extends forward over the back of the ciliary processes and iris,
forming the pars ciliaris retinae and pars iridica retinae, already referred to (Figs. 740
and 757). This forward prolongation consists of the pigmentary layer of the retina,
together with a stratum of columnar epithelium. The portion back of the ora
serrata is called the physiological retina (pars optica retinae) (Fig. 757). The retina
is soft, semi transparent, and of a purple tint in the fresh state, owing to the presence
of a coloring-material named rhodopsin or visual purple; but it soon becomes
clouded, opaque, and bleached when exposed to sunlight. Exactly in the centre
of the front surface of the posterior part of the retina, corresponding to the visual
axis, and at a point in which the sense of vision is most perfect, is an oval yellowish
THE TUNICA INTERNA OR RETINA
1131
spot, called, after its discoverer, the yellow spot of Sb'mmerring (macula luiea] (Figs.
727 and 746), having a central depression, the fovea centralis. The retina in the
situation of the fovea centralis is exceedingly thin, and the dark color of the choroid
is distinctly seen through it; so that it presents more the appearance of a foramen,
and hence the name foramen of Sdmmerring at first given to it. It exists only in
man, the quadrumana, and some saurian reptiles. About one-eighth of an inch (3
mm.) to the nasal side of the yellow spot and one-twenty-fourth of an inch below
it, is the point of entrance of the optic nerve, the optic disk (porus opticus} (Figs.
744 and 746). The circumference of the optic disk is slightly raised so as to form
an eminence, the optic papilla (colliculus nervi optici); the central portion is
depressed and is called the optic cup (excavatio papillae nervi optici). The arteria
centralis retinae pierces its centre. This is the only part of the surface of the retina
from which the power of vision is absent, and is termed the blind spot.
OPTIC
LAMINA CRIBROSR PAPILLA
OF SCLERA
OPTIC
CHOROID — .
POSTERIOR
SHORT CILIARY
ARTERY AND
VEIN
INTERVAGINAL
SPACES
BUNDLES OF
OPTIC NERVE
CENTRAL ARTERY
VEIN OF RETINA
FIG. 744. — The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section. (Toldt.)
Structure. — The optical portion of the retina is an exceedingly complex structure,
and, when examined microscopically by means of sections made perpendicularly
to its surface, is found to consist of many layers of nerve structure. These nerve
structures are bound together and supported by the sustentacular fibres. There
are three layers: a middle or neuro-epithelial layer, an inner layer, and an outer
or pigmentary layer. The neuro-epithelial layer is subdivided into four, and the
middle layer into six layers; hence the retina consists of eleven layers. The layers
from within outward are as follows (Figs. 745, 747, 748, and 749) :
1. Membrana limitans interna.
2. Layer of nerve-fibres (stratum opticum).
3. Ganglionic layer, consisting of nerve-cells.
4. Inner molecular, or plexiform, layer.
5. Inner nuclear layer, or layer of inner granules.
6. Outer molecular, or plexiform, layer.
7. Henle's fibre-layer.
8. Outer nuclear layer, or layer of outer granules.
9. Membrana limitans externa.
10. Jacob's membrane (layer of rods and cones).
3. Outer layer .... 11. Pigmentary layer (tapetum nigrum).
1. Inner layer
2. Neuro-epithelial layer
1132
THE ORGANS OF SPECIAL SENSE
1. The Membrana Limitans Interna (Figs. 745, 747, and 748), is the most internal
layer of the retina, and is in contact with the hyaloid membrane of the vitreous
Pigmentary layer.
Jacob's membrane.
Membrana limitans externa.
Outer nuclear layer.
Outer molecular layer.
Inner nuclear layer.
Fibre of Mutter.
Inner molecular layer.
Ganglionic layer.
Layer of nerve-fibres.
Membrana limitans interna.
FIG. 745. — The layers of the retina with the exception of Henle's fibre-layer. (Diagrammatic.) (After Schultze.)
humor. It is derived from the sup-
porting framework of the retina, with
which tissue it will be described.
2. The Layer of Nerve-fibres (Figs.
745, 747, and 748) is formed by
the expansion of the optic nerve.
This nerve passes through all the
other layers of the retina, except
the membrana limitans interna, to
reach its destination. As the nerve
passes through the lamina cribrosa of
the sclerotic coat, the fibres of which
it is composed lose their myelin
sheaths and are continued onward,
through the choroid and retina, as
simple axones. When these amye-
linic axones reach the internal surface
of the retina, they radiate from their
point of entrance over the surface of the retina, become grouped in bundles, and
in many places, according to Michel, arranged in plexuses. Most of the axones
in this layer are centripetal, and are the direct continuations of the axones of the
FIG. 746. — The arteria centralis retinae, yellow spot, etc., the
anterior half of the eyeball being removed. (Enlarged.)
THE TUNICA INTERNA OR RETINA
1133
cells of the next layer. A few of the axones are centrifugal, which are axones of
ganglion-cells within the brain. The centrifugal fibres in the layer of nerve-fibres
pass through it and the next succeeding layer to ramify in the inner molecular
and inner nuclear layers, where they terminate in enlarged extremities. The
layer is thickest at the optic nerve entrance, and gradually diminishes in thickness
toward the ora serrata.
3. The Ganglionic Layer or the Inner Ganglionic Layer (Figs. 745, 747, and 748)
consists of a single layer of large ganglion-cells; except in the macula lutea,
where there are several strata. The cells are somewhat flask-shaped, the rounded
internal margin of each cell resting on the preceding layer and sending off an axone
which is prolonged as a nerve-fibre into the fibrous layer. From the opposite
extremity numerous thicker processes (dendrites) extend into the inner molecular
layer, where they branch out into flattened arborizations at different levels. The
ganglion-cells vary much in size, and the dendrites of the smaller ones, as a rule,
FIGS. 747 and 748. — Vertical sections of the human retina. Fig. 747, half an inch from the entrance of the
optic nerve. Fig. 748, close to the latter. 1. Layer of rods and cones, Jacob's membrane, bounded underneath
by the membrana limitans externa. 2. Outer nuclear layer. 3. Outer molecular layer. 4. Inner nuclear layer.
5. Inner molecular layer. 6. Ganglionic layer. 7. Layer of nerve fibres. 8. Sustentacular fibres of Miiller.
9. Their attachment to the membrana limitans interns.
arborize in the inner molecular layer as soon as they enter it; while the processes
of the larger cells ramify close to the inner nuclear layer.
4. The Inner Molecular, the Plexiform or the Inner Reticular Layer (Figs. 745, 747,
and 748) is made up of a dense reticulum of minute fibrils, formed by the inter-
lacement of the dendrites of the ganglion-cells with those of the cells contained in
the next layer, immediately to be described. Within the reticulum formed by
these fibrils a few branched spongioblasts are sometimes embedded.
5. The Inner Nuclear or Inner Granular Layer (Figs. 745, 747, and 748) is made up
of a number of closely packed cells, of which there are three different kinds. (1) A
large number of oval cells, which are commonly regarded as bipolar nerve-cells, and
are much more numerous than either of the other kind. They each consist of a
large oval body placed vertically to the surface, and containing a distinct nucleus.
The protoplasm is prolonged into two processes; one of these passes inward into the
inner molecular layer, is varicose in appearance, and ends in a terminal ramification,
which is often in close proximity to the ganglion-cells (Fig. 749, I, c). The outer
process passes outward into the outer molecular layer, and there breaks up into a
THE ORGANS OF SPECIAL SENSE
THE TUNICA INTERN A OR RETINA 1135
number of branches. According to Cajal, there are two varieties of these bipolar
cells: one in which the outer process arborizes around the knobbed ends of the
rod-fibres, and the inner around the cells of the ganglionic layer; these he calls
rod-bipolars (Fig. 749, i) ; the others are those in which the outer process breaks up
in a horizontal ramification, in contact with the end of a cone-fibre; these are the
cone-bipolars, and their inner process breaks up into its terminal ramifications in
the inner molecular layer (Fig. 749, i). (2) At the innermost part of this inner
nuclear layer is a stratum of cells, which are named amacrine cells of Cajal, from the
fact that they have no axis-cylinder process, but they give a number of short proto-
plasmic processes which extend into the inner molecular layer and there ramify
(Fig. 749, i). There are also at the outermost part of this layer some cells-, the
processes of which extend into and ramify in the outer molecular layer. These
are the horizontal cells of Cajal. (3) Some few cells are also found in this layer,
connected with the fibres of Miiller, and will be described with those structures.
6. The Outer Molecular or Outer Reticular Layer or the Plexiform Layer (Figs.
745, 747, and 748) is much thinner than the inner molecular layer; but, like it,
consists of a dense network of minute fibrils, derived from the processes of the
horizontal cells of the preceding layer and the outer processes of the bipolar cells,
which ramify in it, forming arborizations around the ends of the rod-fibres and
with the branched foot-plates of the cone-fibres.
7. Henle's Fibre Layer is a non-granular layer in the neighborhood of the macula
lutea, and is produced by elongations from the inner segments of rod-fibres and
cone-fibres.
8. The Outer Nuclear or Outer Granular Layer (Figs. 745, 747, and 748), like the
inner nuclear layer, contains several strata of clear oval nuclear bodies; they are
of two kinds, and on account of their being respectively connected with the rods
and cones of Jacob's membrane (rod-fibres and cone-fibres) are named rod-
granules and cone-granules.
The rod-granules are much the more numerous, and are placed at different levels
throughout the layer. Their nuclei present a peculiar cross-striped appearance,
and prolonged from either extremity of the granule is a fine process; the outer
process is continuous with a single rod of Jacob's membrane; the inner passes
inward toward the outer molecular layer and terminates in an enlarged extremity,
DESCRIPTION OF FIG. 749.
I. Section of the dog's retina, a. Cone-fibre. 6. Rod-fibre and nucleus, e, d. Bipolar cells (inner granules)
with vertical ramification of outer processes destined to receive the enlarged ends of rod-fibres.
e. Bipolars with flattened ramification for ends of cone-fibres. /. Giant bipolar with flattened ramifica-
tion, fir. Cell sending a neurone or nerve-fibre process to the outer molecular layer, h. Amacrine cell
with diffuse arborization in inner molecular layer, i. Nerve-fibrils passing to outer molecular layer.
j. Centrifugal fibres passing from nerve-fibre layer to inner molecular layer, m. Nervo-fibril passing
into inner molecular layer, n. Ganglionic cells.
II. Horizontal or basal cells of the outer molecular layer of the dog's retina. A. Small cell with dense arbori-
zation. R. Large cell, lying in inner nuclear layer, but with its processes branching in the outer
molecular, a. Its horizontal neurone. C. Medium-sized cell of the same character.
III. Cells from the retina of the ox. a. Rod-bipolars with vertical arborizations. 6, c, d, e. Cone-bipolars with
horizontal ramification of outer process, h. Cell lying on the outer surface of the outer molecular
layer, and ramifying within it. i,j,m. Amacrine cells within the substance of the inner molecular
layer.
IV. Neurones or axis-cylinder processes belonging to horizontal cells of the outer molecular layer, one of them,
b, ending in a close ramification at a.
V. Nervous elements connected with the inner molecular layer of the ox's retina. A. Amacrine cell, with
Jong processes ramifying in the outermost stratum. B. Large amacrine with thick processes ramifying
in second stratum, c. Flattened amacrine with long and fine processes ramifying mainly in the first
and fifth strata. D. Amacrine with radiating tuft of fibrils destined for third stratum. E. Large
amacrine, with processes ramifying in fifth stratum. v. Small amacrine, branching into second
stratum. G, H. Other amacrines destined for fourth stratum, a. Small ganglion-/;ell sending its pro-
cesses to fourth stratum, b. A small ganglion-ceU with ramifications in three strata. C. A small cell
ramifying ultimately in first stratum, d. A medium-sized ganglion-cell ramifying in fourth stratum.
e. Giant-cell, branching in third stratum. /. A bistratified cell ramifying in second and fourth strata.
VI. Amacrines and ganglion-cells from the dog. A. Amacrine with radiating tuft. B. Large amacrine passing
to third stratum. C and Q. Small amacrines with radiations in second stratum. F. Small amacrine
passing to third stratum. D. Amacrine with diffuse arborization. E. Amacrine belonging to fourth
stratum, a, d, e, ff. Small ganglion-cells ramifying in various strata. b,/. Large ganglion-cells show-
ing two different characters of arborization, i. Bistratified cell.
VII. Amacrines and ganglion-cells from the dog. A, B, c. Small amacrines ramifying in middle of molecular
layer. 6, d, g, h, i. Small ganglion-cells showing various kinds of arborization. /. A larger cell, similar
in character to fir, but with longer branch, a, f. e. Giant-cells with thick branches ramifying in the
first, second, and third layers. L, L. Ends of bipolars branching over ganglion-cells.
1136
THE ORGANS OF SPECIAL SENSE
and is embedded in the tuft into which the outer process of the rod-bipolars break
up. In its course it presents numerous varicosities.
The cone-granules, fewer in number than the rod-granules, are placed close to the
membrana limitans externa, through which they are continuous with the cones of
Jacob's membrane. They do not present any cross-striping, but contain a pyri-
form nucleus which almost completely fills the cell. From their inner extremity a
thick process passes inward to the outer molecular layer, upon which it rests by a
somewhat pyramidal enlargement, from which are given off numerous fine fibrils,
A B
External
segment
Intermediary
disc"
Elliptoid--
Nucleus
FIG. 750.— The cells of the rods of the
retina in the frog. A, red rod; B, green
rod. (Poirier and Charpy.)
which enter the outer molecular
layer, where they come in con-
tact with the outer processes of
the cone-bipolars.
9. The Membrana Limitans
Externa(Figs. 745, 747, and 748),
like the membrana limitans in-
terna, is derived from the fibres
of Miiller, with which structures
it will be described.
10. Jacob's Membrane or the
Layer of Rods and Cones (Figs.
745, 747, and 748) consists of
visual Cells, and the elements FIG. 751. — Cones in the different regions of the retina. 7, near
, . . . „ the ora serrata; //, at 3 mm. from the ora serrata; ///, at an
Which COinpOSe it are OI tWO equal distance from the ora serrata and the papilla; IV, at the
periphery of the fovea centralis; V, in the fovea centralis; VI, at
the centre of the fovea centralis; E, length of the external seg-
ment; /, length 9f internal segment; D, diameter of the internal
segment. (Poirier and Charpy.)
kinds, rod-cells and cone-cells,
the former being much more
numerous than the latter.
The rod-cells (Fig. 750) are of nearly uniform size, and arranged perpen-
dicularly to the surface. A rod-cell consists of a rod and a rod-fibre, and the
fibre contains the nucleus. The rods are cylindrical and each consists of two por-
tions, an outer segment and an inner segment, which are of about equal length.
The segments differ from each other as regards refraction and in their behavior
with coloring reagents, the inner portion becoming stained by carmine, iodine, etc.,
the outer portion remaining unstained with these reagents, but staining yellowish-
brown with osmic acid . The outer portion of each rod is marked by transverse striae,
and is made up of a number of thin disks superimposed on one another. It also
THE TUNICA INTERN A OR RETINA 1137
exhibits faint longitudinal markings. The inner portion of each rod, at its deeper
part where it is joined to the outer process of the rod-granule, is indistinctly gran-
ular; its more superficial part presents a longitudinal striation, being composed of
fine, bright, highly refracting fibres. In most vertebrates the outer portion of the
inner segment contains a fibrous body, the ellipsoid of Krause. The visual purple, or
rhodopsin , is found only in the outer segments of the rods. At its inner end each rod
is prolonged into a very fine fibre, the rod-fibre, which contains a nucleus, and which
terminates in the outer nuclear layer, being somewhat enlarged at its termination.
The cone-cells (Fig. 751) are conical or flask-shaped, their broad ends resting
upon the membrana limitans externa, the narrow pointed extremity being turned
to the choroid. Each cone-cell consists of two parts, the cone and the cone-fibre.
The cones are shorter than the rods and exhibit an outer and an inner segment.
The outer segment is a short conical process, which, like the outer segment of a
rod, presents transverse striae. The inner segment resembles the inner portion
of the rods in structure, presenting a superficial striated and deeper granular part;
but differs from it in size, being bulged out laterally and presenting a flask shape.
The inner segment of the cone, as does the rod, contains an ellipsoid of Krause.
Each cone is prolonged into a cone-fibre, and at the junction of the cone with the
fibre is the nucleus of the cone-cell. The cone-fibre passes to the outer nuclear
layer, and terminates as an expansion from which very minute fibrils are given off.
The chemical and optical characters of the rod -cells and cone-cells are identical.
11. The Pigmentary Layer or Tapetum Nigrum(Fig. 745). — The most external layer
of the retina, formerly regarded as a part of the choroid, consists of a single layer
of hexagonal epithelial cells, loaded with pigment-granules. Each cell contains a
flattened nucleus in the outer portion of the cell which is free from pigment at this
point. These cells are smooth externally, where they are in contact with the
choroid, but internally they are prolonged into fine, straight processes, which
extend between the rods, this being especially the case when the eye is exposed to
light. The pigment changes its position under the influence of light, and is dis-
tributed through the entire cell. In the eyes of albinos, the cells of the pigmentary
layer are present, but they contain no coloring-matter. In the eyes of many
mammals also, as in the horse, and many of the carnivora, there is no pigment
in the cells of this layer, and the choroid possesses a beautiful iridescent lustre,
which is termed the tapetum lucidum.
Supporting Framework of the Retina. — Almost all these layers of the retina are
connected together by a supporting framework, formed by the supporting cells or
supporting fibres of Miiller or radiating fibres, from which the membrana limitans
interna et externa are derived. These fibres are found stretched between the two
limiting layers (Fig. 745), "like columns between a floor and a roof," and they
pass through all the nervous layers except Jacob's membrane. Each commences
on the inner surface of the retina by a conical hollow base, which sometimes
contains a spheroidal body which stains deeply with haematoxylin, the edges of
the bases of adjoining fibres being united and thus forming a boundary line, which
is the membrana limitans interna. As they pass through the nerve-fibre and gan-
glionic layers they give off few lateral branches ; in the inner nuclear layer they give
off numerous lateral processes for the support of the inner granules, while in the
outer nuclear layer they form a network, the fibre-baskets, around the rod and
cone-fibrils, and unite to form the external limiting membrane at the bases of
the rods and cones. In the inner nuclear layer each fibre of Miiller presents a clear
oval nucleus, which is sometimes situated at the side of, sometimes altogether
within, the fibre. The supporting framework of the retina contains neuroglia cells.
The Path of Light Stimuli. — The stimulus is first received by the rod and cone-
cells (the visual cells), and is transmitted to the bipolar cells of the inner nuclear
layer and then to the cells of the ganglionic layer, which send fibres by way of the
optic nerve to the brain. 79
1138 THE ORGANS OF SPECIAL SENSE
Macula Lutea and Fovea Centralis. — The structure of the retina at the yellow
spot presents some modifications. In the macula lutea (1) the nerve-fibres are
wanting as a continuous layer; (2) the ganglionic layer consists of several strata
of cells, instead of a single layer; (3) in Jacob's membrane there are no rods, but
only cones, and these are longer and narrower than in other parts; and (4) in the
outer nuclear layer there are only cone-fibres, which are very long and arranged
in curved lines. At the fovea centralis the only parts which exist are the cones
of Jacob's membrane, the outer nuclear layer, the cone-fibres of which are almost
horizontal in direction, and an exceedingly thin inner granular layer, the pigment-
ary layer, which is thicker and its pigment more pronounced than elsewhere. The
color of the macula seems to imbue all the layers except Jacob's membrane; it is
of a rich yellow, deepest toward the centre, and does not appear to consist of
pigment-cells, but simply a staining of the constituent parts.
At the Ora Serrata (Fig. 736) the nerve layers of the retina terminate abruptly,
and the retina is continued onward as a single layer of elongated columnar cells
covered by the pigmentary layer. This prolongation is known as the pars ciliaris
retinae (Fig. 740), and can be traced forward from the ciliary processes on to the
back of the iris, where it is termed the pars iridica retinae or uvea.
From the description given of the nerve elements of the retina it will be seen
that there is no direct continuity between the structures which form its differ-
ent layers except between the ganglionic and nerve-fibre layers, the majority
of the nerve-fibres being formed of the axones of the ganglionic cells. In the
inner molecular layer the dendrites of the ganglionic layer interlace with those
of the cells of the inner nuclear layer, while in the
outer molecular layer a like synapsis occurs between
the processes of the inner granules and the rod and
FOSSA i IKM cone elements.
PATELLAR.S-, Centralis Retinae (Figs. 736 and 744)
and its accompanying vein, vena centralis retinae,
pierce the optic nerve, and enter the globe of the eye
through the porus opticus. It immediately bifurcates
into an upper and a lower branch, and each of these
, ftgain dlvideS illtO an inneF °F naSft1' alld an °Uter OT
with the saucer-shaped hollow in which temporal, branch, which at first run between the
the lens lies. Seen obliquely from the , -T . , , , , , i .1
side and before. (Toidt.) hyaloid membrane and the nerve layer; but they
soon enter the latter, and pass forward, dividing
dichotomously. From these branches a minute capillary plexus is given off, which
does not extend beyond the inner nuclear layer. The macula receives small twigs
from the temporal branches and others directly from the central artery; these do
not, however, reach as far as the fovea centralis, which has no blood-vessels. The
branches of the arteria centralis retinae do not anastomose with each other — in other
words, they are "terminal arteries." In the foetus, a small vessel passes forward,
through the hyaloid canal in the vitreous body, to the posterior surface of the cap-
sule of the lens (Fig. 728).
THE REFRACTING MEDIA.
The Refracting media are three, viz.:
Aqueous humor. Vitreous body. Crystalline lens.
I. The Aqueous Humor (Humor Aqueus).
The aqueous humor completely fills the lymph space known as the aqueous
chamber, the space which is bounded in front by the cornea and behind by the lens
and its suspensory ligament and the ciliary body (Fig. 757) . The aqueous chamber
THE VITREOUS BODY 1139
is partly divided by the iris into two communicating parts, the anterior and posterior
chambers (Figs. 727, 728, and 757). The posterior chamber (cumera oculi posterior)
is only a narrow chink between the peripheral part of the iris, the suspensory
ligament of the lens, and the ciliary processes. The anterior chamber (cumera oculi
anterior is bounded in front by the cornea and behind by the iris. The external
angle of the anterior chamber is bounded by the periphery of the cornea and of
the iris. It is called the angle or sinus of the anterior chamber or the nitration angle
(angulus iridis) . It is by way of the filtration angle that any excess of aqueous
humor passes by way of the spaces of Fontana and the canal of Schlemm (Fig.
740) to the anterior ciliary veins and relieves tension. The aqueous humor is
small in quantity (scarcely exceeding, according to Petit, four or five grains in
weight), has an alkaline reaction, in composition is little more than water, less
than one-fiftieth of its weight being solid matter, chiefly chloride of sodium.
In the adult, these two chambers communicate through the pupil; but in the
foetus of the seventh month, when the pupil is closed by the membrana pupillaris,
the two chambers are quite separate.
II. The Vitreous Body (Corpus Vitreum) (Figs. 725, 728, 752).
The vitreous body forms about four-fifths of the entire globe. It is composed of
a jelly-like tissue containing 98 per .cent, water, some salts, and a little albumin,
and called the vitreous humor (humor vitreus), connective-tissue fibres, and
connective-tissue cells. It fills the concavity of the retina, and is hollowed in
front, forming a deep concavity, the fossa patellaris (fossa hyaloidea) (Fig. 752),
for the reception of the lens. It is perfectly transparent, of the corsistence
of thin jelly, and is composed of an albuminous fluid enclosed in a delicate
transparent membrane, the hyaloid membrane (membrana hyaloidea), the outside
of which is in contact with the membrana limitans interna of the retina. It
has been supposed by Hannover, that from its inner surface numerous thin
lamellae (stroma vitreum) are prolonged inward in a radiating manner, forming
spaces in which the fluid is contained. In the adult, these lamellae cannot be
detected even after careful microscopic examination in the fresh state, but in prep-
arations hardened in weak chromic acid it is possible to make out a distinct
lamellation at the periphery of the body; and in the foetus a peculiar fibrous
texture pervades the mass, the fibres joining at the numerous points, and pre-
senting minute nuclear granules at their point of junction. In the centre of
the vitreous humor, running from the entrance of the optic nerve to the posterior
surface of the lens, is a canal, filled with fluid and lined by a prolongation of the
hyaloid membrane. This is the canal of Stilling, the hyaloid canal, or the canal of
Cloquet (canalis hyaloideus] (Fig. 728), which in the embryonic vitreous humor
conveyed the minute vessel from the central artery of the retina to the back of
the lens.
The hyaloid membrane encloses the whole of the vitreous humor. In front of
the ora serrata it is thickened by the accession of radial fibres and is termed the
zonule of Zinn (zonula ciliaris) (Figs. 755 and 757). It presents a series of radially
arranged furrows, in which the ciliary processes are accommodated and to which
they are adherent, as evidenced by the fact that when removed some of their pig-
ment remains attached to the zonule. The zonule of Zinn splits into two layers, one
of which is thin and lines the fossa patellaris; the other is named the suspensory
ligament of the lens; it is thicker, and passes over the ciliary body to be attached
to the capsule of the lens a short distance in front of its equator. Scattered and
delicate fibres are also attached to the region of the equator itself. This ligament
retains the lens in position, and is relaxed by the contraction of the radial fibres
of the Ciliary muscle, so that the lens is allowed to become more convex. Behind
1140 THE ORGANS OF SPECIAL SENSE
the suspensory ligament there is a sacculated canal, the canal of Petit (spatia
zonularid); which encircles the margin of the lens and which can be easily inflated
through a fine blow-pipe inserted through the suspensory ligament. It is bounded
in front by the anterior layer of the suspensory ligament, of the lens, behind by the
hyaloidea membrana, and internally by the capsule of the lens. The canal of
Petit is a lymph-space. All the spaces of the canal of Petit communicate with the
posterior chamber of the eye.
In the foetus, the centre of the vitreous humor presents the hyaloid canal or
canal of Stilling, already referred to, which transmits a minute artery, the hyaloid
artery, to the capsule of the lens. In the adult, no vessels penetrate its substance,
although a lymph channel remains; so that its nutrition must be carried on by
the vessels of the retina and ciliary processes, situated upon its exterior.
III. The Crystalline Lens (Lens Crystallina) (Figs. 729, 736, 753, 754,
755, 756, 757).
The crystalline lens, enclosed in its capsule, is situated immediately behind the
pupil, in front of the vitreous body, and is encircled by the ciliary processes, which
slightly overlap its margin.
The capsule of the lens (capsula lentis} (Fig. 757) is a transparent, highly elastic,
and brittle membrane, which closely surrounds the lens, and is composed in part of
POSTERIOR
SURFACE
\POSTERIOR
POLE
FIG. 753.— The crystalline lens, hardened
and divided. (Enlarged.) FIG. 754. — The terms used in the orientation 01 the lens, (loldt.)
cuticular and in part of connective tissue. It is not white fibrous tissue, and is not
true elastic tissue (Szymonowicz). Its outer surface is composed of lamella and
possesses transverse striations. It rests, behind, in the fossa patellaris in the fore-
part of the vitreous body (Fig. 752); in front, it is in contact with the free border
of the iris, this latter receding from it at the circumference, thus forming the
posterior chamber of the eye (Fig. 757); and it is retained in its position chiefly by
the suspensory ligament of the lens, already described (Fig. 757). The capsule^s
much thicker in front than behind, and when ruptured the edges roll up with the
outer surface innermost, like the elastic lamina of the cornea.
The substance of the lens (substantia lentis) is an epithelial structure and takes
origin from the ectoderm. It consists early in development of transparent
cylindrical cells, which at a later period become higher at the posterior surface
of the lens. Eventually very long cells form; they are known as lens-fibres (fibrae
lentis}, and are joined by a cement substance. The adult lens consists of lens-
fibres, the anterior surface being covered by one layer of cubical epithelial cells,
known as lens epithelium (epithelium lentis). This layer extends to the margin of
the lens, at which point the cells gain in height and form lens-fibres. The lens-
fibres at the margin are nucleated, the others are not. The lens-fibres run as
meridians from the anterior surface backward. There is no epithelium on the
posterior surface.
THE CRYSTALLINE LENS
1141
In the foetus, a small branch from the arteria centralis retinae runs forward,
as already mentioned, through the vitreous humor to the posterior part of the
capsule of the lens, where its branches radiate and form a plexiform network,
which covers its surface, and they are continuous around the margin of the capsule
with the vessels of the pupillary membrane and with those of the iris. In the adult
no vessels enter its substance.
Structure. — The lens is a transparent, biconvex body, the convexity being greater
on the posterior than on the anterior surface (Fig. 754). The central points of its
ORBICULARIS
CILIARIS
FIG. 755. — The zonule of Zinn or the suspensory ligament of the lens viewed from behind in connection
with the lens and the ciliary body. (Toldt.)
anterior and posterior surfaces are known as its anterior and posterior poles (polus
anterior lentis et polus posterior lentis) (Fig. 754). It measures from 9 to 10 mm.
in the transverse diameter, and about 4 mm. in the antero-posterior. It consists
of concentric layers (Fig. 753), of which the external in the fresh state are soft and
easily detached (substantia corticalis) (Fig. 757) ; those beneath are firmer, the cen-
tral ones forming a hardened nucleus (nucleus lentis) (Fig. 753). These laminae
are best demonstrated by boiling or immersion in alcohol, and consist of minute
parallel fibres, which are hexagonal prisms, the edges being dentated, and the
FIG. 756. — Diagram to show the direction and arrangement of the radiating lines on the front and back of
the total lens. A, from the front; B, from the back.
dentations fitting accurately into each other; their breadth is about ^-gVfr °f an
inch. Faint lines radiate from the anterior and posterior poles to the circumference
of the lens. In the adult there may be six or more of these, but in the foetus they are
only three in number and diverge from each other at angles of 1 20° (Fig. 756). On
the anterior surface one line ascends vertically and the other two diverge down-
ward and outward. On the posterior surface one ray descends vertically and
the other two diverge upward. They correspond with the free edges of an equal
number of septa in the lens, along which the ends of the lens-fibres come into
1142
THE ORGANS OF SPECIAL SENSE
apposition and are joined together by transparent amorphous substance. The
fibres run in a curved manner from the septa on the anteror surface to those on
the posterior surface. No fibres pass from pole to pole, but they are arranged
in such a way that fibres which commence near the pole on the one aspect of
the lens terminate near the peripheral extremity of the plane on the other, and
vice versa. Each fibre of the outer layers of the lens contains a nucleus, and
these nuclei form a layer, the nuclear layer on the surface of the lens. The nuclear
layer is most distinct toward the circumference of the lens.
INSERTION OF
TENDON OF SUPERIOR.
RECTUS MUSCLE
PARS OPTICA
RETIN/E
ORA SERRATA
PARS CILIARIS RETINXE
ANTERIOR CILIARY
ARTERIES AND
VCI
CIRCULAR
MAJOR
PIGMENTARY LAYER
OF RETINA
CHOROID
PERICHOROI DAL SPACE
CIRCULAR
FIBRES
CILIARY
PROCESS
RADIATING FIBRES
OFZONULEOFZINN
ZONUI E OF ZINN
ZONULAR SPACES
POSTERIOR CHAMBER
EPITHELIUM OF
LENS CAPSULE
CAPSULE
OF LENS
ANT. CHAMBER
OF EYE
ANGLE OF
ANTERIOR
CHAMBER
CANAL
SCHLEMM
CONJUNCTIVA
EPISCLERAL
CONNECTIVE-
TISSUE
LIGAMENTUM
PECTINATUM
IRIDIS
RIMA
CORNEALIS
EDGE OF
CORNEA
IRIS (ante-
rior surface)
POSTERIOR
SURFACE
OF CORNEA
EPITHELIUM
OF CORNEA
ANTERIOR
ELASTIC
LAMINA
CORTICAL SUBSTANCE
'OF LENS
POSTERIOR ELASTIC
LAMINA
TROMA OF IRIS
SPHINCTER PIGMENTARY
OF PUPIL LAYERS OF IRIS
FIG. 757. — The upper half of a sagittal section through the front of the eyeball. (Toldt.)
The changes produced in the lens by age are the following:
In the foetus its form is nearly spherical, its color of a slightly reddish tint, it
is not perfectly transparent, and is so soft as to break down readily on the slightest
pressure.
In the adult the posterior surface is more convex than the anterior; it is color-
less, transparent, and firm in texture.
In old age it becomes flattened on both surfaces, slightly opaque, of an amber
tint, and increases in density.
Arteries of the Globe of the Eye. — The arteries of the globe of the eye are the short
posterior ciliary, long posterior ciliary, and anterior ciliary arteries, and the arteria
centralis retinae.
THE CRYSTALLINE LENS 1143
The short posterior ciliary arteries (act. ciliares posteriores breves) (Figs. 734, 736,
and 738) are from eight to sixteen in number. They arise from the ophthalmic
branch of the internal carotid, pass through the sclerotic coat near the optic nerve,
and are distributed to the choroid.
There are two long posterior ciliary arteries (aa. ciliares posteriores longae) (Figs.
734, 736, and 743), one on each side of the optic nerve. They are branches of the
ophthalmic. They pass through the sclerotic external to the short ciliary arteries,
and extend forward in the choroid. In the ciliary body they form an anastomosis
with the anterior ciliary arteries. The anastomosis is known as the circulum iridis
major (Figs. 736 and 757). Branches from this circle pass to the iris, and at the
periphery of the sphincter of the iris form the circulum iridis minor. The muscular
branches and the lachrymal branch of the ophthalmic give off the anterior ciliary
arteries (aa. ciliares anteriores}, six or eight in number. They pass along tendons
of the muscles of the eyeball, reach the sclera, and pass upon the sclera to the
corneal margin (Fig. 743). Branches are given off which pass backward to supply
the anterior half of the sclera, and which are known as episcleral arteries (aa.
episclerales) (Fig. 736). Two branches are given off which pass forward to the
conjunctiva bulbi, which are known as the anterior conjunctival arteries (aa. con-
junctivales anteriores}, which anastomose with the posterior conjunctival branches
from the palpebral arteries, and which .give branches to the delicate vascular net-
work of the corneal margin which is in the annulus conjunctivae (Spalteholz).
Eight or even more branches form the anterior ciliary arteries. They pass through
the sclerotic near the sclero-corneal junction, and participate in the formation of the
circulum iridis major.
The Veins of the Globe of the Eye (Figs. 734, 735, and 736). — The veins are seen
on the outer surface of the choroid. They have a whorl-like formation and empty
into four or five large veins, the venae vorticosae. These four, five, or six equidistant
venae vorticosae pierce the sclerotic midway between the margin of the cornea
and the entrance of the optic nerve, and empty into the ophthalmic vein. Another
set of veins accompany the anterior ciliary arteries, and are known as the anterior
ciliary veins (vv. ciliares anteriores). They are derivatives of the venous sinus of
the sclera in the canal of Schlemm. They form a circular plexus. They receive
vessels, the ciliary muscle, and pass through the sclera close to the corneal margin.
Posterior ciliary veins (w. ciliares posteriores) receive vessels which gather venous
blocd from the outer surface of the sclera near the optic nerve. The posterior
ciliary veins join anteriorly with the venae vorticosae. After emerging from the
sclera they receive anterior conjunctival branches, and by means of episcleral
veins communicate with the venae vorticosae.
The Lymphatic Passages of the Eyeball. — The conjunctiva contains lymph-
vessels. The eyeball contains lymph-spaces, but no lymph- vessels
There are two sets of lymph-spaces in the eyeball, the anterior and posterior.
The anterior lymph-spaces are the spaces of the cornea, of the iris, of the
anterior chamber, and of the posterior chamber.
The lymph from the intralamellar lymph-spaces of the cornea enters the con-
junctival lymphatics at the margin of the cornea.
The lymph-spaces of the iris open into the anterior chamber by the crypts of
the iris and at the margin of the iris join the spaces of Fontana.
The aqueous humor fills the anterior and posterior chambers, but is furnished
by the vessels in the posterior chamber; in part by the vessels of the ciliary body,
and in part by the vessels of the posterior surface of the iris. The lymph thus
secreted passes by way of the pupil into the anterior chamber, and then is taken
up by the spaces of Fontana, the canal of Schlemm, and the anterior ciliary veins.1
1 Deaver's Anatomy.
1144 THE ORGANS OF SPECIAL SENSE
The posterior lymph-spaces are the hyaloid canal, the perichoroklal lymph-
space, the space of Tenon, the intervaginal space of the optic nerve, and the supra-
vaginal space (Deaver).
The hyaloid canal (Figs. 725 and 728) passes between the posterior surface of
the lens and the optic disk. In the embryo the canal holds an artery,1 the hyaloid
artery. During development the artery disappears, but a lymph channel remains.
The hyaloid canal opens into the intervaginal space of the optic nerve. Between
the sclerotic and the choroid is the perichoroidal lymph-space (Fig. 757). It is
around the choroid vessels and the venae vorticosae, and empties into Tenon's
space by means of openings through the sclera about the venae vorticosae.
Tenon's space (Figs. 725 and 726) is between the sclera and the capsule of Tenon.
It receives lymph from the perichoroidal space, and empties into the supravaginal
space.
The optic nerve (Fig. 744) has a sheath of dura and a sheath of pia, and
between these sheaths is the intervaginal lymph-space. It is divided by a pro-
longation of the cerebral arachnoid into a subdural space and a subarachnoid
space, which empty into the corresponding spaces of the membranes of the brain.
The supravaginal space is between the dural portion of the sheath of the optic
nerve and a posterior prolongation of Tenon's capsule.1
The Nerves of the Globe of the Eye. — The long ciliary nerves (nn. ciliares longi),
two in number, are derived from the nasal branch of the ophthalmic and the
short ciliary nerves (nn. ciliares breves], twelve to fifteen in number, are derived
from the ciliary or ophthalmic ganglion. Both the long and short ciliary nerves
perforate the sclera in the neighborhood of the optic nerve (Fig. 734). They pass
along the perichoroidal lymph-space, forming a plexus, and send filaments to the
choroid vessels. In front of the Ciliary muscle they form a second plexus, and
from it come branches which go to the Ciliary muscle and the muscular fibres and
vessels of the iris, sclera, choroid, ciliary body, and iris (Fig. 742). The ciliary
nerves supply the cornea. The circular fibers of the iris are innervated by the
oculomotor nerve and the radiating fibres by the sympathetic.
Surgical Anatomy. — From a surgical point of view the cornea may be regarded as consist-
ing of three layers: (1) of an external epithelial layer, developed from the epiblast, and continu-
ous with the external epithelial covering of the rest of the body, and therefore in its lesions resem-
bling those of the epidermis; (2) of the cornea proper, derived from the mesoblast, and associated
in its diseases with the fibro- vascular structures of the body; and (3) the posterior elastic layer
with its endothelium, also derived from the mesoblast and having the characters of a serous
membrane, so that inflammation of it resembles inflammation of the other serous and synovial
membranes of the body.
The cornea contains no blood-vessels, except at its periphery, where numerous delicate loops,
derived from the anterior ciliary arteries, may be demonstrated on the anterior surface of the
cornea. The rest of the cornea is nourished by lymph, which gains access to the proper sub-
stance of the cornea and the posterior layer through the spaces of Fontana. This lack of a direct
blood-supply renders the cornea very apt to inflame in the cachectic and ill-nourished. In spite
of the absence of blood-vessels, wounds of the cornea usually heal rapidly. A wound which pene-
trates the cornea opens the anterior chamber, and aqueous humor escapes. An ulcer may also
open the anterior chamber. Through a wound or a perforated ulcer the pupillary margin of the
iris may prolapse. A trivial injury of the cornea is repaired by transparent tissue. A severe
injury is repaired by fibrous tissue, and opacity results. A slight opacity resembling a cloud of
gray smoke is called nebula; a more marked white opacity is called leucoma.
In abscess of the cornea pus gravitates between the layers to the lower part of the cornea and
the purulent collection assumes a crescentic shape (onyx).
The arcus senilis, seen in the aged, is a condition of haziness or opacity at the cornea! margin
due to fatty degeneration of the tissue of the cornea. It signifies interference with the blood-
supply, because of senile degeneration of adjacent vessels. In cases of granular lids there is a
peculiar affection of the cornea, called pannus, in which the anterior layers of the cornea become
vascularized, and a rich network of blood-vessels may be seen on the cornea; and in interstitial
keratitis new vessels extend into the cornea, giving it a pinkish hue, to which the term salmon
patch is applied. The cornea is richly supplied with nerves, derived from the ciliary nerves, which
1 For the lymphatic channels of the eyeball see Beaver's Surgical Anatomy, vol. ii. p. 392.
THE CRYSTALLINE LENS 114.')
enter the cornea through the forepart of the sclerotic and form plexuses in the stroma, terminating
between the epithelial cells by free ends or in corpuscles. In cases of glaucoma the ciliary nerves
may be pressed upon as they course between the choroid and sclerotic (Fig. 732), and in conse-
quence of the pressure upon them, the cornea, to which they are distributed, becomes anaes-
thetic. When a scar forms on the cornea and the iris becomes adherent, the scar and the iris,
and sometimes even the lens, may bulge forward from intraocular tension. This condition
is staphyloma of the cornea. In conditions of impaired nutrition the cornea may be bulged for-
ward by intraocular pressure. The line of least resistance is a little below the centre of the
cornea, and it is bulged forward and strongly curved. This condition is known as conical cornea.
The sclerotic has very few blood-vessels and nerves. The blood-vessels are derived from the
anterior ciliary, and form an open plexus in its substance. As they approach the corneal margin
this arrangement is peculiar. Some branches pass through the sclerotic to the ciliary body; others
become superficial and lie in the episcleral tissue, and form arches, by anastomosing with each
other, some little distance behind the corneal margin. From these arches numerous straight
vessels are given off, which run forward to the cornea, forming its marginal plexus. In inflamma-
tion of the sclerotic and episcleral tissue these vessels become conspicuous, and form a pinkish
zone of straight vessels radiating from the corneal margin, commonly known as the zone of ciliary
injection. In inflammation of the iris and ciliary body this zone is present, since the sclerotic
speedily becomes involved when these structures are inflamed. But in inflammation of 'the cornea
the sclerotic is seldom much affected, though the cornea and sclerotic are structurally continuous.
This would appear to be due to the fact that the nutrition of the cornea is derived from a different
source from that of the sclerotic. The sclerotic may be ruptured subcutaneously without any
laceration of the conjunctiva, and the rupture usually occurs near the corneal margin, where
the tunic is thinnest. It may be complicated with lesions of adjacent parts — laceration of the
choroid, retina, iris, or suspensory ligament of the lens — and is then often attended with hemor-
rhage into the anterior chamber, which masks the nature of the injury. In some cases the lens
has escaped through the rent in the sclerotic, and has been found under the conjunctiva. Wounds
of the sclerotic, if they do not perforate, usually heal readily. If they extend through the sclerotic
they cause diminished tension, are always dangerous, and are often followed by inflammation,
suppuration, and by sympathetic ophthalmia. The sclerotic may be weakened by injury, inflam-
mation, etc., and the weakened portion may bulge from intraocular pressure, and even a healthy
sclera may bulge from excessive intraocular pressure. According to its situation the lesion is
known as ciliary staphyloma, equatorial staphyloma, or posterior staphyloma.
One of the functions of the choroid is to provide nutrition for the retina and to convey ves-
sels and nerves to the ciliary body and iris. Inflammation of the choroid is therefore followed
by grave disturbance in the nutrition of the retina, and is attended with early interference with
vision. Purulent choroiditis is not confined to the choroid; the retina, the vitreous, and the entire
uveal tract become involved, and even other structures may suffer. In its diseases it bears a con-
siderable analogy to those which affect the skin, and, like it, is one of the places from which
melanotic sarcomata may grow. These tumors contain a large amount of pigment in their cells,
and grow only from those parts where pigment is naturally present. The choroid may be ruptured
without injury to the other tunics, as well as participating in general injuries of the eyeball. In
cases of uncomplicated rupture the injury is usually at its posterior part, and is the result of a
blow on the front of the eye. It is attended by considerable hemorrhage, which for a time may
obscure vision, but in most cases this is restored as soon as the blood is absorbed.
The iris is the seat of a malformation, termed coloboma, which consists in a deficiency or
cleft, which in a great number of cases is clearly due to an arrest in development. In these cases
it is found at the lower aspect, extending directly downward from the pupil, and the gap fre-
quently extends through the choroid to the entrance of the optic nerve. In some rarer cases the
gap is found in other parts of the iris, and is then not associated with any deficiency of the choroid.
The iris is abundantly supplied with blood-vessels and nerves, and is therefore very prone to
become inflamed. And when inflamed, in consequence of the fact that the iris and ciliary body are
continuous, and that their vessels communicate, iritis is usually associated with cyclitis, the dis-
ease being called irido-cyclitis. And, in addition, inflammation of adjacent structures, the cornea
and sclerotic, is apt to spread into the iris. The iris is covered with endothelium, and partakes of
the character of a serous membrane, and, like these structures, is liable to pour out a plastic exuda-
tion when inflamed, and contract adhesions, either to the cornea in front (synechia anterior), or
to the capsule of the lens behind (synechia posterior). In iritis the lens may become involved,
and the condition known as secondary cataract may be set up. Tumors occasionally commence in
the iris; of these, cysts, which are usually congenital and sarcomatous tumors, are the most common
and require removal. Gummata are not unfrequently found in this situation. In some forms
of injury of the eyeball, as the impact of a spent shot, -the rebound of a twig, or a blow with a
whip, the iris may be detached from the Ciliary muscle, the amount of detachment varying from
the slightest degree to the separation of the whole iris from its ciliary connection.
The Argyll-Robertson pupil shows no reaction to light, but retains reaction to accommodation
and vision remains good.
1146
THE ORGANS OF SPECIAL SENSE
The retina, with the exception of its pigment-layer and its vessels, is- perfectly transparent,
and is invisible when examined by the ophthalmoscope, so that its diseased conditions are
recognized by its loss of transparency. In retinitis, for instance, there is more or less dense and
extensive opacity of its structure, and not unfrequently extravasations of blood into its sub-
stance. Hemorrhages may also take place into the retina from rupture of a blood-vessel without
inflammation.
In optic neuritis, papillitis, or choked disk, the ophthalmoscope shows increase in vascularity,
and swelling and opacity of the nerve, which extend beyond the disk margins. Optic atrophy
is apt to follow. (Fig. 758 shows a normal optic disk.)
The retina may become displaced from effusion of serum between it and the choroid or by
blows on the eyeball, or may occur without apparent cause in progressive myopia, and in this
case the ophthalmoscope shows an opaque, tremulous cloud. Glioma, a form of sarcoma, and
essentially a disease of early life, is occasionally met with in connection with the retina.
The lens has no blood-vessels, nerves, or connective tissue in its structure, and therefore is
not subject to those morbid changes to which tissues containing these structures are liable. It
does, however, present certain morbid or abnormal conditions of various kinds. Thus, variations
in shape, absence of the whole or a part of the lens, and displacements are amongst its congenital
defects. Opacities may occur from injury, senile changes, malnutrition, or errors in growth or
development. An opacity of the capsule, of the lens, or of both, is known as a cataract. Senile
changes may take place in the lens, impairing its elasticity and rendering it harder than in youth,
FIG. 758. — Ophthalmoscopic appearances of healthv FIG. 759. — Ophthalmoscopic appearance of severe
fundus in a person of very fair complexion. Scleral recent papillitis. Several elongated patches of blood
ring well marked. Left eye, inverted image. (Wecker near border of disk. (After Hughlings Jackson.)
and Jaeger. )
so that its curvature can only be altered to a limited extent by the Ciliary muscle. And, finally,
the lens may be dislocated or displaced by blows upon the eyeball, and its relations to surround-
ing structures altered by adhesions or the pressure of new growths.
There are two particular regions of the eye which require special notice: one of these is known
as the " filtratkm area," and the other as the " dangerous area." The filtration area is the circum-
corneal zone immediately in front of the iris. Here are situated the cavernous spaces of
Fontana, which communicate with the canal of Schlemm, through which the chief transudation
of fluid from the eye is now believed to take place. The dangerous area of the eye is the region
in the neighborhood of the ciliary body, and wounds or injuries in this situation are peculiarly
dangerous; for inflammation of the ciliary body is liable to spread to many of the other structures
of the eye, especially to the iris and choroid, which are intimately connected by nervous and
vascular supplies. Moreover, wounds which involve the ciliary region are especially liable to be
followed by sympathetic ophthalmia, in which destructive inflammation of one eye is excited by
some irritation in the other.
Emmetropia is normal vision. In normal vision the practically parallel light rays from distant
objects focus on the retina without effort; divergent rays from near objects are focused on the
retina by an effort of accommodation.
Hyperopm or hypermetropia is far-sightedne,ss. In this condition the retina is in front of the
principal focus when the eye is at rest. The patient endeavors to correct the failure by constant
and tiresome efforts at accommodation. The condition is usually due to inordinate shortness of
the axis of the eye, but may be due to loss of the lens, decreased convexity of the refractive sur-
faces, or lessened refractive power in the refractive media of the eye. It is corrected by the use
of convex glasses.
THE EYELID 1147
Myopia is near-sightedness. In this condition the rays of light come to a focus in front of the
retina, and the patient is subjected to continued eye-strain. It is usually due to too great length
of the axis of the eye, but may result from increase in refractive power of refractive media. It is
corrected by concave glasses. Sometimes, as a person with hyperopia begins to age, an increased
refractive power of the lens causes myopia. The occurrence of myopia in a hyperopic eye is
called second sight, and it enables the individual to cease wearing convex glasses.
Excntrrafion of the contents of the orbit means removal of all the contents except those at the
orbital apex. Even the periosteum is taken away. It is performed for malignant disease.
Kriwration of the eyeball is performed by making a circular incision at the corneal margin and
removing the internal and middle coats and the contents of the globe. The sclera is not removed.
A glass ball is inserted into the scleral sheath, and the sclera is closed over the ball by vertical
stitches, and the conjunctiva is closed over it by transverse stitches. The operation is performed
for leucoma or staphyloma of the cornea. An artificial eye (a shell) is placed over the stump
when healing is complete.
Enuclcation, or excision of the eyeball, differs from exenteration of the orbital contents in the
fact that only the eyeball is removed. A circular incision through the ocular conjunctiva
is carried around and near to the corneal margin. The conjunctiva and capsule of T£non are
pushed back and the Rectus muscles are clamped and divided back of the clamp. Traction
is made upon the globe in a forward and inward direction, and the optic nerve and adjacent
structures are cut with scissors from the outer aspect of the globe. The eye is then pulled out of
the orbit, and all structures which tend to retain it are divided. The stumps of the Recti muscles
are sewed together.
THE APPENDAGES OF THE EYE (TUTAMINA OCULI).
The appendages of the eye include the eyebrows, the eyelids, the conjunctiva,
and the lachrymal apparatus — viz., the lachrymal gland, the lachrymal sac, and the
nasal duct.
The Eyebrow (Supercilium) .
The eyebrows are two arched eminences of integument which surmount the
upper circumference of the orbit on each side, and support numerous short, thick
hairs, directed obliquely on the surface. The hairs may entangle foreign bodies
and lessen somewhat the force of blows. In structure the eyebrows consist of
thickened integument, connected beneath with the Orbicularis palpebrarum,
Corrugator supercilii, and Occipito-frontalis muscles. These muscles serve, by
their action on this part, to control to a certain extent the amount of light
admitted into the eye.
The Eyelid (Palpebra) (Figs. 760, 761).
The eyelids are two thin, movable folds placed in front of the eye, and by closure
protecting the eye from injury. The eyelids are composed of skin, superficial
fascia, and areolar tissue, fibres of the Orbicularis palpebrarum muscle, palpebral
and orbito-tarsal ligaments, tarsal cartilages, and conjunctiva. The upper lid
also contains the Levator palpebrae superioris muscle. In the lids are blood-vessels,
lymph-vessels, nerves, and Meibomian glands. There are two lids, the upper
(palpebra superior) and the lower (palpebra inferior). The upper lid is the larger
and the more movable of the two, and is furnished with a separate elevator
muscle, the Levator palpebrae superioris. Each lid consists of two portions. The
part near the orbital margin, "whose groundwork is formed merely by the thin
palpebral fascia (septum orbitale),"1 is called the orbital portion (pars orbitalis).
The part in which the tarsus lies is called the tarsal portion ( pars tarsalis). Between
the two portions in each lid is a sulcus, called, in the upper lid, the superior orbito-
palpebral sulcus (sulcus orbitopalpebralis superior), and, in the lower lid, the inferior
orbito -palpebral sulcus (sulcus orbitopalpebralis inferior). When the eyelids are
1 An Atlas of Human Anatomy. By Carl Toldt, assisted by A. D. Rosa. Translated by M. Eden Paul.
THE ORGANS OF SPECIAL SENSE
opened an elliptical space, the interpalpebral slit (fissura palpebraruni), is left
between their margins, the angles of which correspond to the junction of the upper
and lower lids, and are called canthi.
The Canthi. — The outer canthus (angulus oculi lateralis) is more acute than the
inner, and the lids here lie in close contact with the globe; but the inner canthus
(angulus oculi medialis] is prolonged for a short distance inward toward the nose.
The two lids are separated at the inner canthus by a triangular space, the lacus
lacrimalis. At the commencement of the lacus lacrimalis, on the margin of each
eyelid, is a small conical elevation, the lachrymal papilla, the apex of which is
pierced by a small orifice, the punctum lacrimale (Fig. 764), the commencement of
the lachrymal canal (Fig. 763). When the lids are closed a space remains between
them and the globe to permit of the flow of tears inward (rivus lacrimalis').
The Eyelashes (cilia) (Fig. 761). — The eyelashes are attached to the free edges of
the eyelids; they are short, thick, curved hairs, arranged in a double or triple row
at the margin of the lids; those of the upper lid, more numerous and longer than
the lower, curve upward; those of the lower lid curve downward. Because of this
arrangement the two sets do not interlace in closing the lids. Near the attachment
of the eyelashes are the openings of sebaceous glands (glandulae sebaceae) (Fig. 761)
and of a number of glands, glands of Moll (glandulae ciliares [Molli]) (Fig. 761),
arranged in several rows close to the free margin of the lid. They are regarded as
enlarged and modified sweat-glands. On the inner surface are the Meibomian
glands (Fig. 763). Internal to the openings of the lachrymal canaliculi there are
neither lashes nor Meibomian glands.
LACHRYMAL ARTERY.
AND NERVE
EXTERNAL LATERA
LIGAMENT
-SUPRAORBITAL VES-
SELS AND NERVE
LACHRYMAL SAC
INTERNAL LATE-
RAL LIGAMENT
FIG. 760. — The tarsi and their ligaments. Right eye, front view. (Testut.)
Structure of the Eyelids (Fig. 761). — The eyelids are composed of the following
structures, taken in their order from without inward:
Integument, areolar tissue, fibres of the Orbicularis muscle, tarsal plate, and
its ligament, Meibomian glands, and conjunctiva. The upper lid has, in addition,
the aponeurosis of the Levator palpebrse.
The integument is extremely thin, and continuous at the margin of the lids with
the conjunctiva.
The subcutaneous areolar tissue is very lax and delicate, seldom contains any
fat, and is extremely liable to serous infiltration.
The fibres of the Orbicularis muscle, where they cover the palpebrae (m. ciliaris
[Riolani]), are thin, pale in color, and possess an involuntary action.
TIIK EYELID
1149
The tarsal plates are two thin elongated plates of dense connective tissue about
an inch in length. They are placed one in each lid, contributing to their form
and support.
The superior tarsal plate, superior tarsus or superior tarsal body (tarsus superior)
(Fig. 760), the larger, is of a semilunar form, about one-third of an inch in
breadth at the centre, and becoming gradually narrowed at each extremity. To
the anterior surface of this plate the aponeurosis of the Levator palpebrae is
attached.
The inferior tarsal plate, inferior tarsus or inferior taxsal body (tarsus inferior]
(Fig. 760), the smaller of the two, is thinner and of an elliptical form.
The free or ciliary margin of these plates is thick, and presents a perfectly
straight edge. The attached or orbital margin is connected to the circumference of
the orbit by the fibrous membrane of the
lids, with which it is continuous. The
outer angle of each plate is attached to
the malar bone by the external tarsal or
external lateral ligament, or the external
palpebral ligament or raphe (ligamentum
palpebralis later alis) (Fig. 760). The inner
angles of the two plates terminate at the
commencement of the lacus lacrimalis;
they are attached to the nasal process
of the superior maxilla by the internal
tarsal or internal lateral or internal palpe-
bral ligament or the tendo oculi (ligamen-
fin/t palpebrale mediate) (Fig. 760).
The fibrous membrane of the lids con-
stitutes the orbito-tarsal ligaments or the
palpebral fasciae. In reality these so-called
ligaments are fascial expansions situated
one in each lid, and are attached margin-
ally to the edge of the orbit, where they
are continuous with the periosteum. The
superior ligament blends with the tendon
of the Levator palpebrae, the inferior with
the inferior tarsal plate. Externally the
superior and inferior ligaments fuse to
form the external tarsal ligament or raphe
just referred to; internally they are much
thinner, and, becoming separated from
the internal tarsal ligament, are fixed to
the lachrymal bone immediately behind
the lachrymal sac. Together the liga-
ments form an incomplete Septum, the .
Orbital SeptUin (septum Orbitale), Which is ginal 'fasciculus ofr ort^ularis (dliaryUIbundle) &c
perforated by the vessels and nerves which tfB£S3&^*,?tiS^i£tt ^
pass from the orbital cavity to the face jpS^^tt^^^SS^"1^ *'
and scalp.
The Meibomian or Tarsal Glands (glandulae tarsales [Meibomi]) (Figs. 761 and
763). — The Meibomian or tarsal glands are situated upon the inner surface of the
eyelids between the tarsal plates and conjunctiva, and may be distinctly seen
through the mucous membrane on everting the eyelids, presenting the appearance
of parallel strings of pearls. They are about thirty in number in the upper eyelid,
and somewhat fewer in the lower. They are embedded in grooves in the inner
b'. f
FIG. 761. — Vertical section through the upper eye
1150 THE ORGANS OF SPECIAL SENSE
surface of the tarsal plates, and correspond in length with the breadth of each plate;
they are, consequently, longer in the upper than in the lower eyelid. Their ducts
open on the free margin of the lids by minute foramina, which correspond in num-
ber to the follicles. The use of their secretion is to prevent adhesions of the lids.
Structure of the Meibomian Glands.— These glands are a variety of the cutaneous
sebaceous glands, each consisting of a single straight tube or follicle, having a
caecal termination, and with numerous small secondary follicles opening into it.
The tubes consist of basement-membrane, lined at the mouths of the tubes by
stratified epithelium; the deeper parts of the tubes and the secondary follicles are
lined by a layer of polyhedral cells. They are thus identical in structure with the
sebaceous glands.
The Conjunctiva (Figs. 727, 728, 740, 762).
The conjunctiva is the mucous membrane of the eye. It lines the inner surface
of the eyelids, is reflected over the forepart of the sclerotic and cornea, and joins
the lids to the eyeball. In each of these situations its structure presents some
peculiarities.
The Palpebral Portion (tunica conjunctiva palpebrarum) (Fig. 763). — The palpe-
bral portion of the conjunctiva lines the posterior surface of the lids. It is thick,
opaque, highly vascular, and covered with numerous papillae, its deeper parts
presenting a considerable amount of lymphoid tissue. At the margin of the lids
it becomes continuous with the lining membrane of the ducts of the Meibomian
glands, and, through the lachrymal canals, with the lining membrane of the
lachrymal sac and nasal duct. At the outer angle of the upper lid the lachrymal
ducts open on its free surface; and at the inner angle of the eye it forms a semi-
lunar fold, the plica semilunaris (plica semilunaris conjunctivae) (Fig. 764). The
folds formed by the reflection of the conjunctiva from the lids on to the eye are
called the superior and inferior palpebral folds, the former being the deeper of the
two. These folds form the superior and inferior conjunctival fornix (Fig. 762).
The Bulbar Portion (tunica conjunctiva bulbi) . — Upon the sclerotic the conjunc-
tiva is loosely connected to the globe ; it becomes thinner, loses its papillary struc-
ture, is transparent, and only slightly vascular in health. Upon the cornea the con-
junctiva consists only of epithelium, constituting the ante-
rior layer of the cornea (conjunctival epithelium) already
described (p. 1119). Lymphatics arise in the conjunc-
tiva in a delicate zone around the cornea, from which the
vessels run to the ocular conjunctiva.
Fornix of Conjunctiva. — At the point of reflection of
each fold of the conjunctiva from the lid on to the globe
of the eye a pocket or arch is formed. These arches are
-INFERIOR FORNIX l T l • • • .• /TV TOON
termed the fornix conjunctivae (Fig. 762).
FIG. 762— Sagittal section Glands of Conjunctiva. — In the conjunctiva there are a
of eye, showing superior and . . . . , .
inferior fomices .of the con- number of mucous glands which are much convoluted.
junctiva. (Testut.) mi , . n f ° , . ., i. , y^,, i .
They are chiefly found in the upper lid. Other glands,
analogous to lymphoid follicles, and called by Henle trachoma glands, are found
in the conjunctiva, and, according to Stromeyer, are chiefly situated near the
inner canthus of the eye. They were first described by Brush, in his description
of Peyer's patches of the small intestines, as " identical structures existing in the
under eyelid of the ox."
The Nerves of the Conjunctiva. — The nerves in the conjunctiva are numerous and
form rich plexuses. According to Krause, they terminate in a peculiar form of
tactile corpuscle, which he terms the terminal bulb.
The Caruncula Lacrimalis. — The caruncula lacrimalis is a small, reddish, conical-
shaped body, situated at the inner canthus of the eye, and filling up the small
SUPERIOR FORNIX
THE LACHRYMAL APPARATUS
1151
triangular space in this situation, the lacus lacrimalis. It consists of an island
of skin containing sebaceous and sweat-glands, and is the source of the whitish
secretion which constantly collects at the inner angle of the eye. A few slender
hairs are attached to its surface. On the outer side of the caruncula is a slight
semilunar fold of conjunctiva, the concavity of which is directed toward the
cornea; it is called the plica semilunaris (Fig. 764). Miiller found smooth mus-
cular fibres in this fold, and in some of the domesticated animals a thin plate of
cartilage has been discovered. This structure is considered to be the rudiment
of the third eyelid in birds, the membrana nictitans.
The Lachrymal Apparatus (Apparatus Lacrimaiis) (Figs. 763, 764).
The lachrymal apparatus consists of the lachrymal gland, which secretes the
tears, and its excretory ducts, which convey the fluid to the surface of the eye.
This fluid is carried away by the lachrymal canals into the lachrymal sac, and along
the nasal duct into the cavity of the nose.
The Lachrymal Glands (glandula lacrimalis}. — The lachrymal gland is lodged
in a depression at the outer angle of the orbit, on the inner side of the external
Puncta lachrymalia.
FIG. 763. — The Meibomian glands, etc., seen from the inner surface of the eyelids.
angular process of the frontal bone. It is of an oval form, about the size and
shape of an almond. Its upper convex surface is in contact with the. periosteum
of the orbit, to which it is connected by a few fibrous bands. Its under concave
surface rests upon the convexity of the eyeball and upon the Superior and External
recti muscles. Its vessels and nerves enter its posterior border, whilst its anterior
margin is closely adherent to the back part of the upper eyelid, where it is covered
to a slight extent by the reflection of the conjunctiva. The forepart of the gland
is separated from the rest by a fibrous septum ; hence it is sometimes described as
a separate lobe, called the inferior lachrymal gland, palpebral portion of the gland,
or the accessory gland of Rosenmuiler (glandula lacrimalis inferior), the back part
of the gland then being called the superior lachrymal gland (glandula lacrimalis
superior). The ducts of the lachrymal gland, from six to twelve in number,
run obliquely beneath the mucous membrane for a short distance, and, separating
from each other, open by a series of minute orifices on the upper and outer half of
the conjunctiva near its reflection on to the globe. These orifices are arranged in
a row, so as to disperse the secretion over the surface of the membrane.
Structure of the Lachrymal Gland. — In structure and general appearance the
lachrymal resembles the serous salivary glands. In the recent state the cells are so
THE ORGANS OF SPECIAL SENSE
FIG. 764. —The lachrymal apparatus. Right side.
crowded with granules that their limits can hardly be defined. Each cell contains
an oval nucleus, and the cell-protoplasm is finely fibrillated.
The Lachrymal Canaliculi or Canals (Fig. 764) commence at the minute orifices,
puncta lacrimalia, on the summit of a small conical elevation, the lachrymal papilla
or caruncle (carunculus lacrimalis), seen on the margin of the lids at the outer ex-
tremity of the lacus lacrimalis. The superior canal (ductus lacrimalis superior], the
smaller and shorter of the two, at first ascends, and then bends at an acute angle,
and passes inward and downward to the ampulla. The inferior canal (ductus
lacrimalis inferior} at first descends,
and then, abruptly changing its course,
passes almost horizontally inward to
the ampulla. These canals are dense
and elastic in structure and somewhat
dilated at their angle. The mucous
membrane is covered with scaly epi-
thelium. The two canals join in a
dilatation, the ampulla (ampulla ductus
lacrimalis), which empties into the
lachrymal sac.
The Lachrymal Sac (saccus lacri-
malis} (Fig. 764) .—The lachrymal sac is
the upper dilated extremity of the nasal
duct, and is lodged in a deep groove
formed by the lachrymal bone and the
nasal process of the superior maxillary
bone. It is oval in form, its upper ex-
tremity being closed in and rounded,
whilst below it is continued into the nasal duct. It is covered by a fibrous
expansion derived from the tendo oculi, and on its deep surface it is crossed by
the Tensor tarsi muscle (Horner's muscle, p. 373), which is attached to the ridge
on the lachrymal bone.
Structure. — It consists of a fibrous elastic coat, lined internally by mucous mem-
brane, the latter being continuous, through the ampulla and lachrymal canals,
with the mucous lining of the conjunctiva, and, through the nasal duct, with the
pituitary membrane of the nose.
The Nasal Duct (ductus nasolacrimalis) (Fig. 764). — The nasal duct is a
membranous canal, about three-quarters of an inch in length, which extends from
the lower part of the lachrymal sac to the inferior meatus of the nose, where it
terminates by a somewhat expanded orifice, provided with an imperfect valve, the
valve of Hasner (plica lacrimalis [Hasneri]), formed by the mucous membrane. It
is contained in an osseous canal formed by the superior maxillary, the lachrymal,
and the inferior turbinated bones, is narrower in the middle than at each extrem-
ity, and takes a direction downward, backward, and a little outward. It is lined
by mucous membrane, which is continuous below with the pituitary lining of
the nose. The membrane in the lachrymal sac and nasal duct is covered with
columnar epithelium, as in the nose. This epithelium is in places ciliated.
Surface Form.— The palpebrcd fissure, or opening between the eyelids, is elliptical in shape,
and differs in size in different individuals and in different races of mankind. In the Mongolian
races, for instance, the opening is very small, merely a narrow fissure, and this makes the eye-
ball appear small in these races, whereas the size of the eye is relatively very constant. The
normal direction of the fissure is slightly oblique, in a direction upward and outward, so that the
outer angle is on a slightly higher level than the inner. This is especially noticeable in the Mon-
golian races, in whom, owing to the upward projection of the malar bone and the shortness of
the external angular process of the frontal bone, the tarsal plate of the upper lid is raised at its
outer part and gives an oblique direction to the palpebral fissure.
THE LACHRYMAL APPARATUS 1153
When the eyes are directed forward, as in ordinary vision, the upper part of the cornea is
covered by the upper lid, and the lower margin of the cornea corresponds to the level of the
lower lid, so that about the lower three-fourths of the cornea is exposed under ordinary circum-
stances. On the margins of the lids, about a quarter of an inch from the inner canthus, are two
small openings, the punda lacrimalia, the commencement of the lachrymal canals. They are
best seen by everting the eyelids. In the natural condition they are in contact with the con-
junctiva of the eyeball, and are maintained in this position by the Tensor tarsi muscle, so that
the tears running over the surface of the globe easily find their way into the lachrymal canals.
The position of the lachrymal sac into which the canals open is indicated by a little tubercle,
which is plainly to be felt on the lower margin of the orbit. The lachrymal sac lies immediately
above and to the inner side of this tubercle, and a knife passed through the skin in this
situation would open the cavity. The position of the lachrymal sac may also be indicated by
the tendo oculi or internal tarsal ligament. If both lids be drawn outward, so as to tense the
skin at the inner angle, a prominent cord will be seen beneath the tightened skin. This is the
truth oculi, which lies immediately over the lachrymal sac, bisecting it, and thus forming a useful
guide to its situation. A knife entered immediately beneath the tense cord would open the
lower part of the sac. A probe introduced through this opening can be readily passed down-
ward through the duct into the inferior meatus of the nose. The direction of the duct is down-
ward, outward, and backward, and this course should be borne in mind in passing the probe,
otherwise the point may be driven through the thin bony walls of the canal. A convenient
plan is to direct the probe in such a manner that if it were pushed onward it would strike
the first molar tooth of the lower jaw on the same side of the body. In other words, the
surgeon standing in front of his patient should carry in his mind the position of the first
molar tooth, and should push his probe onward in such a way as if he desired to reach this
structure.
Beneath the internal angular process of the frontal bone the pulley of the Superior oblique
muscle of the eye can be plainly felt by pushing the finger backward between the upper and inner
angle of the eye and the roof of the orbit; passing backward and outward from this pulley, the
tendon can be felt for a short distance.
Surgical Anatomy.— The eyelids are composed of various tissues, and consequently are liable
to a variety of diseases. The skin which covers them is exceedingly thin and delicate, and is
supported on a quantity of loose and lax subcutaneous tissue which contains no fat. In conse-
quence of this it is very freely movable, and is liable to be drawn down by the contraction of
neighboring cicatrices. Such contractions may produce an eversion of the lid known as ectropion.
Inversion of the lids (entropion) from spasm of the Orbicularis palpebrarum or from chronic
inflammation of the palpebral conjunctiva may also occur. In some individuals there is an extra
row of eyelashes on the inner margin of the lid, directed toward the cornea (distichiasis). Trich-
iasis is a condition in which the lashes are directed toward the eye, but there is not inversion of
the lid. The eyelids are richly supplied with blood, and are often the seat of vascular growths,
such as ncrvi. Rodent ulcer also frequently commences in this situation. The loose cellular tissue
beneath the skin is liable to become extensively infiltrated either with blood or inflammatory
products, producing very great swelling. Even from very slight injuries to this tissue the extrava-
sation of blood may be so great as to produce considerable swelling of the lids and complete
closure of the eye, and the same is the case when inflammatory products are poured out. The
follicles are liable to become inflamed, constituting the disease known as marginal blepharitis,
blepharitis ciliaris, or ''blear-eye." Irregular or disorderly growth of the eyelashes not unfre-
quently occurs, some of them being turned toward the eyeball and producing inflammation and
follicles of the eyelashes or the sebaceous glands associated with these follicles may be the seat of
inflammation, constituting the ordinary hordeolum or "sty." The Meibomian glands are affected
in the so-called '' tarsal tumor;" the tumor, according to some, being caused by the retained secre-
tion of these glands; by others it is believed to be a neoplasm connected with the gland. The Orbic-
ularis palpebrarum may be the seat of spasm (blepharospasm), either in the form of slight quiv-
ering of the lids or repeated twitchings, most commonly due to errors of refraction in children,
or more continuous spasm, due to some irritation of the fifth or seventh cranial nerves. The
Orbicularis may be paralyzed, generally associated with paralysis of the other facial muscles.
Under these circumstances the patient is unable to close the lids, and if he attempts to do so,
rolls the eyeball upward under the upper lid. The tears overflow from displacement of the lower
lid, and the conjunctiva and cornea, being constantly exposed and the patient being unable to
wink, become irritated from dust and foreign bodies. As a result there may be ulceration of
the cornea, and possibly eventually complete destruction of the eye. In paralysis of the Levator
palpebrae superioris there is drooping of the upper eyelid (ptosis) and other symptoms of impli-
cation of the third nerve. The eyelids may be the seat of bruises, wounds, or burns. After
wounds or burns adhesions of the margins of the lids to each other or adhesion of the lids to
the globe may take place. The eyelids are sometimes the seat of emphysema after fracture of
some of the thin bones forming the inner wall of the orbit. If shortly after such an injury the
patient blows, his nose, air is forced from the nostrils through the lacerated structure into the
73
1154 THE ORGANS OF SPECIAL SENSE
connective tissue of the eyelids, which suddenly swell up and present the peculiar crackling on
pressure which is characteristic of this affection.
Foreign bodies frequently get into the conjunctival sac and cause great pain, especially if
they come in contact with the corneal surface, during the movements of the lid and the eye on
each other. The conjunctiva is frequently involved in severe injuries of the eyeball, but is seldom
ruptured alone; the most common form of injury to the conjunctiva alone is from a burn, either
from fire, strong acids, or lime. In these cases union is liable to take place between the eyelid
and the eyeball. The conjunctiva is often the seat of inflammation arising from many different
causes, and the arrangement of the conjunctival vessels should be remembered as affording a
means of diagnosis between this condition and injection of the sclerotic, which is present in
inflammation of the deeper structures of the globe. The inflamed conjunctiva is bright red; the
vessels are large and tortuous, and greatest at the circumference, shading off toward the corneal
margin; they anastomose freely and form a dense network, and they can be emptied by gentle
pressure.
The lachrymal gland is occasionally, though rarely, the seat of inflammation (dacryoadenitis) ,
either acute or chronic; it is also sometimes the seat of tumors, benign or malignant, and for these
may require removal. This may be done by an incision through the skin just below the eyebrow;
and the gland, being invested with a special capsule of its own, may be isolated and removed
without opening the general cavity of the orbit. The canaliculi may be obstructed, either as a
congenital defect or by some foreign body, as an eyelash or a dacryolith, causing the tears to run
over the cheek. The canaliculi may also become occluded as the result of burns or injury; over-
flow of tears may in addition result from deviation of the puncta or from chronic inflammation
of the lachrymal sac. When there is failure of the lachrymal tubes to drain off the tears and
the fluid gathers beneath and flows over the lids, the condition is known as epiphora or stilli-
cidium. This latter condition is set up by some obstruction to the nasal duct frequently occurring
in tuberculous subjects. In consequence of this the tears and mucus accumulate in the lachrymal
sac, distending it. Suppuration in the lachrymal sac (dacryocystitis) is sometimes met with;
this may be the sequel of a chronic inflammation; or may occur after some of the eruptive fevers
in cases where the lachrymal passages were previously quite healthy. It may lead to lachrymal
fistula.
THE EAR (ORGANON AUDITUS).
The organ of hearing is divisible into three parts — the external ear, the middle
ear or tympanum, and the internal ear or labyrinth.
THE EXTERNAL EAR (AURIS EXTERNA).
The external ear consists of an expanded portion named pinna or auricle, and
the auditory canal or meatus. The former serves to collect the vibrations of the air
by which sound is produced; the latter conducts those vibrations to the tympanum.
The Pinna or Auricle (Auricula) (Fig. 765).
The pinna or auricle is attached to the side of the head midway between the
forehead and occiput. "Its level is indicated by horizontal lines extending back-
ward from the eyebrows above and from the tip of the nose below." (Hensman.)
It is of an ovoid form, with its larger end directed upward. Its outer surface is irreg-
ularly concave, directed slightly forward. The angle which it bears to the head is
called the cephalo- auricular angle. In some cases this angle is almost absent. In
others it is nearly a right angle. The pinna of one side may vary in size, shape, and
angle from the pinna of the other side. The pinna of a woman is apt to be smaller
than that of a man, and is less often deformed. The outer surface of the pinna
presents numerous eminences and depressions which result from the foldings of its
fibro-cartilaginous element. To each of these, names have been assigned. Thus
the external prominent rim of the auricle is called the helix . Another curved prom-
inence, parallel with and in front of the helix, is called the antihelix; this bifurcates
above and forms the crura (crura anthelicis), which encloses a triangular depression,
the fossa of the antihelix (fossa triangularis [auriculae]). The narrow curved depres-
sion between the helix and antihelix is called the fossa of the helix or the scaphoid
THE PINNA OR A URICLE
1155
fossa (scapha) ; the antihelix describes a curve around a deep, capacious cavity, the
concha auriculae, which is partially divided into two parts by the crus of the helix (crus
helicis),or the commencement of the helix; the upper part is termed the cymba-
OARWINIAN
TUBERCLE
FOSSA
TRIANGULARIS
CRURA OF
ANTIHELIX
SCAPHOID
FOSSA
INCISURA
ANTERIOR
TUBERCULUM
SUPRATRAGICUM
EXTERNAL
AUDITORY
MEATUS
INCISURA
INTEHTRAGICA
POSTERIOR
AURICULAR •
SULCUS
CAVUM CONCHAE
FIG. 765. — The right pinna or auricle, viewed from without.
(Spalteholz.)
INSERTION
OF SUPERIOR
AURICULAR
MUSCLE
INSERTION
AURICULAR
MUSCLE
OBLIQUE
AURICULAR
MUSCLE
conchae, the lower part the cavum
conchae In front of the concha,
and projecting backward over the
meatus, is a small pointed emi-
nence, the tragus, so called from
its being generally covered on its OF ANTERIOR
,» . AURir.lll AR
under surface with a tuft of hair
resembling a goat's beard. Oppo-
site the tragus, and separated from
it by a deep notch (incisuria inter-
tragicd), is a small tubercle, the
antitragus. Below this is the lobule
(lobulus auriculae), composed of
tough areolar and adipose tissue,
wanting the firmness and elasticity
of the rest of the pinna. Some-
times the lobule does not hang
freely, but is adherent. Where
the helix turns downward a small tubercle, tubercle of Darwin (tuberculum auric-
ulae [Darwini]), is frequently seen. This tubercle is very evident about the sixth
month of foetal life; at this stage the human pinna has a close resemblance to that
of some of the adult monkeys.
INSERTION OF
POSTERIOR
AURICULAR
MUSCLE
TRANSVERSE
AURICULAR
MUSCLE
CARTILAGE
OF EXTERNAL
AUDITORY
MEATUS
FIG. 766. — The cartilages of the right auricle, isolated, with,
the muscles, viewed trom the inside. (Spalteholz.)
1156
THE ORGANS OF SPECIAL SENSE
The cranial surface of the pinna presents elevations which correspond to the
depressions on its outer surface and after which they are named, e. g., eminentia
conchae, eminentia fossae triangularis, etc.
The eminentia conchae and the fossae triangularis are separated by a furrow
(sulcus antihelicis transversus) , which corresponds to the inferior crus of the anti-
helix, or groove (sulcus cruris helicis), and upon the eminence there is a vertical
ridge, the ponticulus, which indicates the point of insertion of the Retrahens
auriculam muscle.
Structure of the Pinna. — The pinna is composed of a thin plate of yellow
fibre-cartilage, covered with integument, and connected to the surrounding parts
by the extrinsic ligaments and muscles, and to the commencement of the external
auditory canal by fibrous tissue.
The Integument. — The integument is thin, closely adherent to the cartilage, and
covered with hairs furnished with sebaceous glands, which are most numerous in
the concha and scaphoid fossa. The hairs are most numerous and largest on the
tragus and antitragus.
The Cartilage of the Pinna (cartilago auriculae) (Fig. 767) . — The cartilage of the
pinna consists of one single piece; it gives form to this part of the ear, and upon its
surface are found all the eminences
and depressions above described.
It does not enter into the construc-
tion of all parts of the auricle ; thus
it does not form a constituent part
of the lobule; it is deficient also
between the lamina of the tragus
and beginning of the crus helix, the
notch between (incisura terminalis
auris)ihem being filled up by dense
fibrous tissue. At the front part of
the pinna,where the helix bends up-
ward, is a small projection of car-
tilage, called the spine of the helix
(spina helicis), while the lower part
of the helix is prolonged downward
as a tail-like process, the cauda
helicis; this is separated from the
antihelix by a fissure, the fissura antitragohelicina. The fissures of Santorini are
usually two in number: one in the substance of the tragus, which partially separates
the different parts, and one in the cartilage of the meatus. The fissure of the helix
is a short vertical slit, situated at the forepart of the pinna. Another fissure, the
fissure of the tragus, is seen upon the anterior surface of the tragus. Anteriorly
and inferiorly the cartilage of the pinna is continuous with the cartilage of the
external auditory meatus by a cartilaginous isthmus (isthmus cartilaginis amis).
Some authors regard the tragus as part of the cartilage of the meatus. The
cartilage of the pinna is very pliable, elastic, of a yellowish color and belongs to
that form of cartilage which is known under the name of yellow fibro-cartilage.
The Ligaments of the Pinna (ligamenti auricularia [Valsalv'ae]). — The ligaments
of the pinna consist of two sets: 1. The extrinsic set, or those connecting it to the
side of the head. 2. The intrinsic set, or those connecting the various parts of its
cartilage together.
The Extrinsic Ligaments, the most important, are three in number: superior,
anterior, and posterior. The superior ligament (ligamentum auriculare superius)
extends from the suprameatal spine to the spine of the helix. The anterior ligament
(ligamentum auriculare anterius) extends from the spina helicis and tragus to the
FISSURA
ANTITRAGICO-
HELICINA
TRIANGULAR
FOSSA
SPINE OF
HELIX
CRUS OF
HELIX
LAMINA
TRAGI
INCISURA
TERMINALIS
AURIS
INCISURA
INTERTRAGICA
ANTITRAGUS
FIG. 767.— The right ear cartilages, isolated, viewed from
without. (Spalteholz.)
THE PINNA OR AURICLE
1157
root of the zygoma. The posterior ligament (licjamentum auriculare posterius)
passes from the posterior surface of the concha to the outer surface of the mastoid
process of the temporal bone.
The chief Intrinsic Ligaments are: (1) a'strong fibrous band, stretching across
from the tragus to the commencement of the helix, completing the meatus in front,
and partly encircling the boundary of the concha; and (2) a band which extends
between the antihelix and the cauda helicis. Other less important bands are
found on the cranial surface of the pinna.
The Muscles of the Pinna (Figs. 766 and 768) . — The muscles of the pinna consist
of two sets : 1 . The extrinsic, which connect it with the side of the head, moving the
pinna as a whole — viz., the Attollens, Attrahens, and Retrahens auriculam (p. 372).
2. The intrinsic, which extend from one part of the auricle to another, viz. :
Helicis major.
Helicis minor.
Tragicus.
Antitragicus.
Transversus auriculae.
Obliquus auriculae.
The Helicis Major (m. helicis major} is a narrow vertical band of muscular
fibres, situated upon the anterior margin of the helix. It arises, below, from the
spina helicis, and is inserted into
the anterior border of the helix, just
where it is about to curve backward.
It is pretty constant in its existence.
The Helicis Minor (m. helicis minor)
is an oblique fasciculus which covers
the crus helicis.
The Tragicus (m. tragicus) is a
short, flattened band of muscular
fibres situated upon the outer surface
of the tragus, the direction of its
fibres being vertical.
The Antitragicus (m. antitragicus)
arises from the outer part of the anti-
tragus; its fibres are inserted into the
cauda helicis and antihelix. This
muscle is usually very distinct.
The Transversus Auriculae (m.
transversus auriculae) is placed on
the cranial surface of the pinna. It
consists of scattered fibres, partly
tendinous and partly muscular, ex-
tending from the convexity of the
concha to the prominence corre-
sponding with the groove of the helix.
The Obliquus Auriculae (Tod) (m.
obliquus auriculae) consists of a few
fibres extending from the upper and back part of the concha to the convexity
immediately above it.
The Arteries of the Pinna. — The arteries of the pinna are the posterior auricular
from the external carotid, the anterior auricular from the temporal and an auric-
ular branch from the occipital artery.
The Veins of the Pinna. — The veins of the pinna accompany the corresponding
arteries.
The Lymphatics of the Pinna. — The lymphatics enter into the pre-auricular glands
and the glands upon the Sterno-mastoid muscle at its insertion.
FIG. 768. — The muscles of the pinna.
1158 THE ORGANS OF SPECIAL SENSE
The Nerves of the Pinna. — The nerves of the pinna are: the great auricular,
from the cervical plexus; the auricular branch of the vagus; the auriculo-temporal
branch of the inferior maxillary nerve; the small occipital from the cervical
plexus, and the great occipital or internal branch of the dorsal division of the
second cervical nerve. The muscles of the pinna are supplied by the facial nerve.
The External Auditory or External Acoustic Canal or External Auditory
Meatus (Meatus Acusticus Externus or Meatus
Auditorius Externus).
The external auditory or acoustic canal or meatus extends from the bottom
of the concha to the membrana tympani (Figs. 765, 769, and 770). It is about
an inch and a half in length if measured from the tragus; from the bottom of
the concha its length is about an inch. It forms a sort of S-shaped curve, and is
directed at first inward, forward, and slightly upward (pars externa); it then
passes inward and backward (pars media], and lastly is carried inward, forward,
and slightly downward (pars interna). It forms an oval cylindrical canal, the
greatest diameter being in the vertical direction at the external orifice, but in the
Cartilage of
the pinna ~
Promont.
Int. carat, a.
Membrana
tympani
Cartilage of 'the ext. A .' : )
auditory meatus
FIG. 769. — Transverse section of external auditory meatus and tympanum. Left side. (Gegenbaur.)
transverse direction at the tympanic end. It presents two constrictions, one
near the inner end of the cartilaginous portion, and another, the isthmus, in the
osseous portion, about three-quarters of an inch from the bottom of the concha.
The membrana tympani (Figs. 769 and 770), which occupies the termination of the
meatus, is directed obliquely, in consequence of which the floor of the canal is
longer than the roof, and the anterior wall longer than the posterior. The auditory
canal is formed partly by cartilage and membrane, partly by bone, and is lined by
perichoridrium and periosteum, which is covered with skin.
The Cartilaginous Portion (meatus acusticus externus cartilagineus}. — The car-
tilaginous portion is about one-third of an inch (8 mm.) in length; it is formed
by the cartilage of the pinna, prolonged inward, and firmly attached to a greater
portion of the circumference of the auditory process of the temporal bone. The
cartilage is deficient at its upper and back part, its place being supplied by fibrous
membrane. This part of the canal is rendered extremely movable by two or
three deep fissures, the fissures of Santorini (incisurae cartilaginis meatus acustici
externi [Santorini\) , which extend through the cartilage in a vertical direction.
It is firmly attached at its lower and front part to the middle root of the zygoma
and to the lateral edge of the tympanic portion of the temporal bone.
THE EXTERNAL AUDITORY MEATUS
1159
The Osseous Portion (meatus acusticus externus osseus). — The osseous por-
tion is about two-thirds of an inch (16 mm.) in length, and narrower than the
cartilaginous portion. It is directed inward and a little forward, forming a slight
curve in its course, the convexity of which is upward and backward. Its inner
end, which communicates, in the dry bone, with the cavity of the tympanum, is
smaller than the outer and sloped, the anterior wall projecting beyond the poste-
rior about two lines; it is marked, except at its upper part, by a narrow groove,
the tympanic sulcus (sidcus tympanicus], for the insertion of the mernbrana tym-
pani. Its outer edge is dilated and rough in the greater part of its circumference,
for the attachment of the cartilage of the pinna. Its vertical transverse section
is oval, the greatest diameter being from above downward. The front and lower
parts of this canal are formed by a curved plate of bone, which, in the foetus,
exists as a separate ring (annulus tympanicus), incomplete at its upper part. (See
Section on Osteology.)
FENESTRA OVALIS
CLOSED BY STAPES
FIG. 770. — Vertical section through the external auditory meatus and tympanum, passing in front of the
fenestra ovalis. (Testut.)
The Skin of the Meatus. — The skin lining the meatus is a prolongation of the
external skin; it is thin, adheres closely to the cartilaginous and osseous portions
of the tube, and covers the surface of the membrana tympani, forming a very
thin outer layer. After maceration the thin pouch of epidermis, when withdrawn,
preserves the form of the meatus. In the thick subcutaneous tissue of the cartil-
aginous part of the meatus are numerous ceruminous glands (glandulae ceruminosae)
which secrete the ear-wax. They resemble in structure sweat-glands, and their
ducts open on the surface of the skin.
Relations of the Meatus. — In front of the osseous part is the glenoid fossa, which
receives the condyle of the mandible (Fig. 762), which, however, is separated from
the cartilaginous part by the retromandibular part of the parotid gland. The
movements of the jaw influence to some extent the lumen of the cartilaginous
portion. Behind the osseous part are the mastoid air-cells (cellulae mastoideae),
separated from it by a thin layer of bone (Fig. 46).
The Arteries of the External Meatus. — The arteries supplying the external meatus
are branches from the posterior auricular, internal maxillary, and superficial
temporal.
s
1160 THE ORGANS OFi SPECIAL SENSE
The Veins of the External Meatus. — Veins accompany the corresponding arteries
and pass to the internal maxillary, temporal, and posterior auricular veins.
The Lymphatics of the External Meatus. — The lymphatics accompany the veins
and enter the parotid and posterior auricular lymph-glands.
The Nerves of the External Meatus. — The nerves are derived from the auriculo-
temporal branch of the inferior maxillary nerve, the auricularis magnus, and the
auricular branch of the vagus.
Surface Form. — The point of junction of the osseous and cartilaginous portions of the tube
is an obtuse angle, which projects into the canal at its antero-inferior wall. This produces a
sort of constriction in this situation, and renders it the narrowest portion of the canal — an impor-
tant point to be borne in mind in connection with the presence of foreign bodies in the ear.
The cartilaginous is connected to the bony part by fibrous tissue, which renders the outer part
of the tube very movable, and therefore by drawing the pinna upward and backward the canal
is rendered almost straight. At the external orifice are a few short, crisp hairs which serve to
prevent the entrance of small particles of dust, flies or other insects. In the external auditory
meatus the secretion of the ceruminous glands serves to catch any small particles which may
find their way into the canal, and prevent their reaching the membrana tympani, where their
presence might excite irritation. In young children the meatus is short, the osseous part
being very deficient, and consisting merely of a bony ring (annulus tympanicus], which supports
the membrana tympani. In the fretus the osseous part is entirely absent. The shortness of the
canal in children should be borne in mind in introducing the aural speculum, so that it shall not
be pushed in too far, at the risk of injuring the membrawa tympani; indeed, even in the adult the
speculum should never be introduced beyond the constriction which marks the junction of the
osseous and cartilaginous portions. In using this instrument it is advisable that the pinna
should be drawn upward, backward, and a little outward, so as to render the canal as straight as
possible, and thus assist the operator in obtaining, by the aid of reflected light, a good view of
the membrana tympani. Just in front of the membrane is a well-marked depression, situated
on the floor of the canal and bounded by a somewhat prominent ridge; in this foreign bodies
may become lodged. By aid of the speculum, combined with traction of the auricle upward
and backward, the whole of the membrana tympani is rendered visible. It is a pearly-gray mem-
brane, slightly glistening in the adult, placed obliquely, so as to form with the floor of the meatus
a very acute angle (about 55 degrees), while with the roof it forms an obtuse angle. At birth it
is more horizontal — being situated in almost the same plane as the base of the skull. About
midway between the anterior and posterior margins of the membrane, and extending from the
centre obliquely upward, is a reddish-yellow streak; this is the handle of the malleus, which is
inserted into the membrane (Fig. 773). At the upper part of this streak, close to the roof of the
meatus, a little white rounded prominence is plainly to be seen; this is the processus brevis of
the malleus, projecting against the membrane. The membrana tympani does not present a
plane surface; on the contrary, its centre is drawn inward, on account of its connection with the
handle of the malleus, and thus the external surface is rendered concave.
THE MIDDLE EAR, DRUM OR TYMPANUM (AURIS MEDIA)
(Figs. 769, 770, 771, 775).
The middle ear or tympanum is an irregular cavity, compressed from without
inward, and is situated within the petrous portion of the temporal bone. It is
placed above the jugular fossa; the carotid canal lying in front, the mastoid cells
behind, the external auditory meatus externally, and the labyrinth internally. It is
lined with mucous membrane, is filled with air, and communicates with the mas-
toid cells, and with the naso-pharynx by the Eustachian tube. The tympanum is
traversed by a chain of movable bones, which connect the membrana tympani
with the labyrinth, and serve to convey the vibrations communicated to the mem-
brana tympani across the cavity of the tympanum to the internal ear. In shape
it is roughly biconcave, the concave surfaces being placed vertically and forming
the external and internal walls. The cavity forms an angle of 45 degrees with the
median plane (Spalteholz).
The Tympanic Cavity (cavum tympani) (Figs. 775 and 776).— The tympanic
cavity consists of two parts: the atrium or tympanic cavity proper (Fig. 776),
opposite the tympanic membrane, and the attic or epitympanic recess or aditus
ad antrum (recessus epitympanicus) (Figs. 774 and 775), above the level of the
THE MIDDLE EAR, DRUM OR TYMPANUM
1161
upper part of the membrane; the latter contains the upper half of the malleus
and the greater part of the incus. The diameter of the tympanic cavity,
including the attic, measures about f- inch (15 mm.) vertically and trans-
versely. From without inward it measures about £ inch (6 mm.) above and £
inch (4 mm.) below; opposite the centre of the tympanic membrane it is only
about y1^- inch (2 mm.). It is bounded externally by the membrana tympani and
meatus; internally, by the outer surface of the internal ear; and communicates
behind with the mastoid antrum and through it with the mastoid cells; and in
front with the Eustachian tube and canal for the Tensor tympani. Its roof and
floor are formed by thin osseous laminae, the one forming the roof being a thin
plate situated on the anterior surface of the petrous portion of the temporal bone,
close to its angle of junction with the squamous portion of the same bone.
The Roof of the Tympanum (paries tegmentalis). — The roof of the tympanum
is broad, flattened, and formed of a thin plate of bone (legmen tympani} (Fig.
775), which separates the cranial and tympanic cavities. It is prolonged back-
ward so as to roof in the mastoid antrum; it is also carried forward to cover in
the canal for the Tensor tympani muscle.
The Floor (paries jugularis) (Fig. 775). — The floor is narrow, and is separated
by a thin plate of bone (jundus tympani) from the jugular fossa. It frequently
Chorda tympani
FIG. 771. — View of the inner wall of the tympanum (enlarged).
presents numerous small notches in the bone (cellulae tympanicae). There is one
small aperture in the floor. It is near the inner wall and is the opening of the
canaliculus tympanicus, for the transmission of Jacobson's nerve (n. tympanicus).
On the floor near the posterior wall there is often to be found a slight bony
projection (prominentia styloideae}.
The Outer Wall (Fig. 770). — The outer wall is formed mainly by the membrana
tympani, partly by the ring of bone into which this membrane is inserted. The
part formed by the membrana tympanum is called the paries membranaceus. This
ring of bone is incomplete at its upper part, forming a notch, the notch of Rivinus
(incisura tympanica [Rivini]) (Fig. 773). The anterior edge of the notch is
known as the spina tympanica major, the posterior edge as the spina tympanica
minor. The .groove for the reception of the membrana tympani is the sulcus
tympanicus. Close to the notch are three small apertures: the iter chordae pos-
terius, the Glaserian fissure, and the iter chordae anterius.
The iter chordae posterius or the tympanic aperture (canalicutus chordae tympani)
(Fig. 774) is in the angle of junction between the posterior and external walls of
the tympanum, immediately behind the membrana tympani and on a level with the
upper end of the handle of the malleus; it leads into a minute canal, which descends
1162 THE ORGANS OF SPECIAL SENSE
in front of the aquaeductus Fallopii, and terminates in the aqueduct near the
stylomastoid foramen. Through it the chorda tympani nerve enters the tym-
panum.
The Glaserian or petro-tympanic fissure (fissura petrotympanica [Glaseri]} (Fig.
774) opens just above and in front of the ring of bone into which the membrana
tympani is inserted; in this situation it is a mere slit about a line in length. It
lodges the long process and anterior ligament of the malleus, and gives passage
to the tympanic branch of the internal maxillary artery.
The iter chordae anterius (Fig. 774) is seen at the inner end of the preceding
fissure; it leads into a canal, the canal of Huguier, which runs parallel with the
Glaserian fissure. Through it the chorda tympani nerve leaves the tympanum.
The outer wall bounds the epitympanic recess externally.
The Internal Wall of the Tympanum (paries labyrinthica} (Figs. 771 and 775). —
The internal wall of the tympanum is adjacent to the labyrinth, is vertical in direc-
tion, and looks directly outward. It presents for examination the following parts :
Fenestra ovalis. Promontory.
Fenestra rotunda. Ridge of the aquaeductus Fallopii.
Prominence of the external semicircular canal.
The Fenestra Ovalis, the Oval or the Vestibular Window (fenestra vestibuli) (Fig.
771) is a reniform opening leading from the tympanum into the vestibule. It
is situated in the depths of a fossa (fossula fenestrae vestibuli}. Its long diameter
is directed horizontally, and its convex border is upward. The opening in the
recent state is occupied by the base of the stapes (Figs. 770 and 776), which is
connected to the margin of the foramen by an annular ligament.
The Fenestra Rotunda, the Round or Cochlear Window (fenestra cochleae} (Fig.
771), is an aperture placed at the bottom of a funnel-shaped depression (fossula
fenestrae cochleae} leading into the cochlea. It is situated below and rather
behind the fenestra ovalis, from which it is separated by a rounded elevation, the
promontory; at its border is a narrow ridge of bone (crista fenestrae cochleae},
which is closed in the recent state by a membrane, the membrane of Scarpa or the
secondary ear-drum membrane (membrana tympani secundaria}. This membrane
is concave toward the tympanum, convex toward the cochlea. It consists of
three layers: the external or mucous, derived from the mucous lining of the
tympanum; the internal, from the lining membrane of the cochlea; and an inter-
mediate or fibrous layer.
The Promontory (promontorium) (Fig. 775) is a rounded hollow prominence,
formed by the projection outward of the first turn of the cochlea; it is placed
between the fenestrse, and is furrowed on its surface (sulcus promontorii} for the
lodgement of the tympanic plexus. A minute spicule of bone frequently connects
the promontory to the pyramid.
The Rounded Eminence of the Aquaeductus Fallopii (prominentia canalis facialis}
(Fig. 775), the prominence of the bpny canal in which the facial nerve is contained,
traverses the inner wall of the tympanum above the fenestra ovalis, and behind
that opening curves nearly vertically downward along the posterior wall.
Just above the eminence of the aquaeductus Fallopii the wall is bulged by the
external semicircular canal (prominentia canalis semicircularis lateralis}.
The Posterior Wall of the Tympanum (paries mastoidea} (Fig. 775). — The pos-
terior wall of the tympanum is wider above than below, and the lower portion of/
the posterior wall contains many tympanic cells. The posterior wall presents for
examination the —
Opening of the antrum. Prominentia styloideae.
Fossa incudis. Pyramid.
Apertura tympanica canaliculi chordae.
THE MIDDLE EAR, DRUM OR TYMPANUM 1163
The Opening of the Antrum is a large irregular aperture, which extends back-
ward from the epityrapanic recess and leads into a considerable air space, the*
mastoid antrum (antrum tympanicum) , which is the entrance to the mastoid cells
(p. 87). The antrum communicates with large irregular cavities contained
in the interior of the mastoid process, the mastoid air-cells. These cavities vary
considerably in number, size, and form; they are lined by mucous membrane
continuous with that lining the cavity of the tympanum.
The Fossa Incudis (Fig 775) is placed in the posterior and inferior part of the
epitympanic recess. It lodges the short process of the incus.
The Prominentia Styloideae is sometimes seen below the apertura tympanica
canaliculi chordae. It is a prominence produced by a prolongation of the styloid
process.
The Pyramid (eminentia pyramidalis) (Fig. 771) is a conical eminence situated
immediately behind the fenestra ovalis, and in front of the vertical portion of the
eminence above described; it is hollow in the interior, and contains the Stapedius
muscle; its summit projects forward toward the fenestra ovalis, and presents a
small aperture which transmits the tendon of the muscle. The cavity in the
pyramid is prolonged into a minute canal, which communicates with the aquae-
ductus Fallopii and transmits the nerve which supplies the Stapedius.
The Apertura Tympanica Canaliculi Chordae is just back of the posterior edge of the
tympanic membrane, nearly level with the superior end of the manubrium mallei.
The Anterior Wall of the Tympanum (paries carotica). — The anterior wall of
the tympanum is bony on its lower portion. Its upper part is the tympanic
opening of the Eustachian tube. The long anterior wall contains tympanic
cells. The anterior wall is wider above than below; it corresponds with the
carotid canal, from which it is separated by a thin plate of bone (Fig. 775), per-
forated by the canaliculi caroticotympanici, which transmit the tympanic branch
of the internal carotid artery and the carotico-tympanic nerves. It presents for
examination the —
Canal for the Tensor tympani. Orifice of the Eustachian tube.
The processus cochleariformis.
The orifice of the canal for the Tensor tympani and the orifice of the Eustachian
tube are situated at the upper part of the anterior wall, being incompletely sepa-
rated from each other by a thin, delicate, horizontal plate of bone, the processus
cochleariformis (septum cancdis musculotubarii) (Figs. 49 and 771). The canalis
musculotubarius is divided by this long process into the canal for the Tensor
tympani and the canal for the Eustachian tube. These canals run from the
tympanum forward, inward, and a little downward, to the retiring angle between
the squamous and petrous portions of the temporal bone.
The Canal for the Tensor Tympani (semicanalis m. tensoris tympani) (Figs. 49,
771, and 775) is the superior and the smaller of the two; it is rounded and lies
beneath the forward prolongation of the tegmen tympani. It extends on to the
inner wall of the tympanum and ends immediately above the fenestra ovalis. The
processus cochleariformis passes backward below this part of the canal, forming
its outer wall and floor; it expands above the anterior extremity of the fenestra
ovalis and terminates by curving outward so as to form a pulley over which the
tendon passes. The bony wall of this canal is incomplete, and the osseous vacancy
is filled by tough connective tissue.
The Eustachian Tube or Ear Trumpet (tuba auditiva [Eustachii]) (Figs. 49,
771, and 772) is the channel through which the tympanum communicates with
the pharynx. Its length is an inch and a half (36 mm.), and its direction
downward, inward, and forward, forming an angle of about 45 degrees with
the sagittal plane and one of from 30 to 40 degrees with the horizontal plane.
1164
THE ORGANS OF SPECIAL SENSE
The canal for the Eustachian tube (semicanalis tubae auditivae) (Fig. 772) is formed
partly of bone, partly of cartilage and fibrous tissue.
The Osseous Portion (pars ossea tubae auditivae or semicanalis tubae auditivae)
is about half an inch in length. It is the outer portion of the tube. It commences
in the anterior wall of the tympanum, below the processus cochleariformis (ostium
tympanicum tubae auditivae}, and, gradually narrowing, terminates at the angle
of junction of the petrous and squamous portions of the temporal bone, its
extremity presenting a jagged margin which serves for the attachment of the
cartilaginous portion. The roof of the osseous portion is the tegmen tympani.
The inner wall is formed in part by the inner wall of the tympanum and in part
by the canal for the Tensor tympani muscle. The outer wall is the tympanic
portion of the temporal bone. The floor is a groove which near the tympanum
contains the openings of air-cells (cellulae pneumatici tubarii).
TENSOR TYMPANI
MEMBRANA
TYMPAN
.PHARYNGEAL OPEN-
ING OF TUBE
FIG. 772. — Eustachian tube, laid open by a cut in its long axis. (Testut.)
The Cartilaginous Portion (pars cartilaginea tubae auditivae), about an inch in
length, is formed of a triangular plate of elastic fibre-cartilage (cartilago tubae
auditivae), the apex of which is attached to the margin of the inner extremity of
the osseous canal, while its base lies directly under the mucous membrane of
the naso-pharynx, where it forms an elevation or cushion above and behind the
pharyngeal orifice of the tube. The upper edge of the cartilage is curled upon
itself, being bent outward so as to present on transverse section the appearance of
a hook (lamina lateralis); a groove or furrow is thus produced, which opens below
and externally, and this part of the canal is completed by fibrous membrane. On
transverse section the cartilage exhibits the laminae which above are continuous
o
with each other: the hard, thick lamina medialis and the thin and hooked lamina
lateralis. The cartilage of the Eustachian tube, with a hood plate of cartilage,
forms the posterior portion of the inner wall (the lamina medialis). The cartilage
is fixed to the base of the skull, and lies in a groove (sulcus tubae auditivae)
between the petrous-temporal and the greater wing of the sphenoid ; this groove
ends opposite the middle of the internal pterygoid plate, in a projection, the
THE MIDDLE EAR, DRUM OR TYMPANUM
1165
processus tubarius. At the pharyngeal orifice the entire wall of the tube is cartil-
aginous, but the breadth of the cartilage progressively lessens as the isthmus is
approached. Here and there the cartilage is deficient or pieces lie separate from
the rest, the spaces between the islands being occupied by fibrous tissue. The Ten-
sor palati muscle is placed to the outer side of the tube. The fibres of the muscle
which take origin from the lamina lateralis are known as the dilator tubae muscle of
Rudinger. The Tensor palati muscle and the mucous membrane of the pharynx lie to
the inner side of the tube. The under and outer portion of the canal is completed
by the membranous part (lamina membranaced}, which is a strong fibrous mem-
brane, passing between the two margins of the cartilage. It is thin above, but thick
below, and the thick portion is called the fascia salpingopharyngea of Trbltsch,
and from it arise some fibres of the Tensor palati (m. salpingopharyngeus). The
cartilaginous and bony portions of the tube are not in the same plane, the former
POSTERIOR TYMPANO-
MALLCOLAR FOLD
FLACCID PORTION OF
MCMBRANA TYMPANI
POSTERIOR
TYMPANIC
SPINE
MARGIN OF
MEMBRANA
TYMPANI
OR LIMBUS
MALLEOLAR
PROMINENCE
NOTCH OF
RIVINUS
ANTERIOR
TYMPANO-
MALLEOLAR
FOLD
HANDLE OF
.MALLEOLUS
SEEN THROUGH
MEMBRANE
TENSE PORTION
OF MEMBRANA
TY M PA N I
FIG. 773. — The right membrana tympani, viewed from the outside, from in front, and from below. (Spalteholz.)
inclining downward a little more than the latter. They join each other at a large
obtuse angle, open below. The diameter of the canal is not uniform throughout,
being greatest at the pharyngeal orifice and least at the junction of .the bony and
cartilaginous portions, where it is named the isthmus (isthmus tubae auditivae) ;
it again expands somewhat as it approaches the tympanic cavity. The
position and relations of the pharyngeal orifice (ostium pharyngeum tubae
auditii'ae) are described with the anatomy of the naso-pharynx. Through this
canal the mucous membrane of the pharynx is continuous with that which lines
the tympanum. The mucous membrane is covered with ciliated epithelium and
is thin in the osseous portion, while in the cartilaginous portion it contains many
mucous glands and near he pharyngeal orifice a considerable amount of adenoid
tissue, which has been named by Gerlach the tube-tonsil. The tube is opened
during deglutition by the Salpingo-pharyngeus and Dilator tubae muscles.
The Drumhead or Membrana Tympani (Figs. 770, 772, 773, and 774).— The
membrana tympani or drumhead separates the cavity of the tympanum from
1166
THE ORGANS OF SPECIAL SENSE
the bottom of the external meatus. It is a thin, semi-transparent membrane,
nearly oval in form, somewhat broader above than below, and directed very
obliquely downward and inward, so as to form an angle of about 55 degrees
with the floor of the rneatus (Fig. 770). The antero-inferior portion is, there-
fore, placed at the greatest distance from the external orifice of the meatus. It
is asserted that in musicians the rnembrana tympani is placed more nearly per-
pendicular, and that in deaf-mutes and cretins it is placed more obliquely than
the usual 55 degrees. In a newborn child the membrana tympani is almost hori-
zontal. The greatest diameter of the membrana tympani is from 9 to 10mm.;
SUPERIOR LIGAMENT
OF MALLEOLUS
E PITY M PA NIC
RECESS
NCCK OF
MALLEUS\
ANTERIOR LIGAMENT
AND ANTERIOR
PROCESS OF
MALLEOLUS
INSERTION
OF TENSOR
TYMPANI
MUSCL
GLASERIAN
FISSURE
ARTICULAR SURFACE
FOR BODY OF INCUS
FLACCID PORTION OF
MEMBRANA TYMPANB
POSTERIOR
TYMPANIC
SPINE
TYMPANIC
ORIFICE
OF CANAL
FOR CHORDA
TYMPANI
NERVE
EUSTACHIAN
TUBE
TENSE PORTION OF
MEMBRANA TYMPANI
FIG. 774. — The right membrana tympani with the hammer and the chorda tympani, viewed from within,
from behind, and from above. (Spalteholz.)
its least diameter is from 8 to 9 mm. (Cunningham). The greater part of its cir-
cumference (limbus membranae tympanae) is thickened to form an annular ring
(annulus fibrocartilagineus] , which is fixed in a groove, the sulcus tympanicus, at
the inner extremity of the external meatus. This sulcus is deficient superiorly at
the incisure or notch of Rivinus (incisura tympanica [Rivini]) (Fig. 773). From the
extremities of the notch (spinae tympanicae) two folds pass and converge to the
short process of the malleus (Fig. 773). One is known as the anterior tympano-
malleolar fold or ligament (plica membrana tympani anterior) . The other is known
as the posterior tympano-malleolar fold or ligament (plica membrana tympani pos-
terior). These are not to be confused with the anterior and posterior malleolar
folds (p. 1172). The small, somewhat triangular part of the membrane situated
above these folds is lax and thin, and is named the flaccid portion or the membrana
flaccida of Shrapnell (Figs. 773 and 774). In it a small orifice is sometimes seen,
which is of artificial and pathological formation. The larger lower portion of the
drum membrane is stretched tightly, and is called the tense portion or pars tensa
(Figs. 773 and 774).
THE MIDDLE EAR, DRUM OR TYMPANUM
1167
The handle of the malleus is firmly attached to the inner aspect of the mem-
brana tympani as far as its centre (Fig. 774). It draws the central part of the
membrane inward and makes its outer aspect concave. The most depressed part
of the concavity is called the umbo or navel (umbo membranae tympanae) (Fig. 773).
The walls of the umbo are concave outward.
On the outer surface of the drum membrane a light stripe (stria mcdleolaris) is
seen. It runs from in front and above downward and backward, and is produced
by the handle of the malleus, showing through the membrane (Fig. 773).
Structure. — This membrane is composed of three layers: an external (cuticular) t
a middle (fibrous], and an internal (mucous). The cuticular lining (stratum cuta-
neum) is derived from the integument lining the meatus. The fibrous or
middle layer (membrana propria) consists of two strata: an external, of radiating
fibres (stratum radiatum), which diverge from the handle of the malleus, and an
JUNCTION BETWEEN MAS-
TOID ANTRUM AND
EPITYMPANIC RECESS
I TEGMEN
* TYMPANI
I EPITYMPANIC
T RECESS
PROMINENCE OF EXTERNAL
SEMICIRCULAR CANAL
PROMINENCE OF AQUEDUCT
OF FALLOPIUS
TENDON OF
STAP.EDIUS MUSCLE
PLICA
/ / STAPEDIUS
PROCESSUS
COCHLEARIFORMIS
TENSOR TYMPANI
MUSCLE (cut through)
WALL OF
LABYRINTH
POSTERIOR
SINUS
PYRAMIDAL
EMINENCE
TY M PA N I C
SINUS
FOSSULA OF JUGULAR TYMPANIC
FENESTRA ROTUNDA WALL PLEXUS
FIG. 775. — The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral
view. (Spalteholz.)
internal, of circular fibres (stratum circular -e), which are plentiful around the cir-
cumference, but sparse and scattered near the centre of the membrane. Branched
or dendritic fibres, as pointed out by Griiber, are also present, especially in the
posterior half of the membrane. Both muscular layers are connected to the
annulus fibrocartilagineus, and both are absent in the pars flaccida. The inner
or epithelial layer is mucous membrane (stratum mucosum), which is a portion
of the mucous membrane of the drum cavity.
The Arteries are derived from the deep auricular branch of the internal maxil-
lary, which ramifies beneath the cuticular layer and from the stylo-mastoid branch
of the posterior auricular and tympanic branch of the internal maxillary, which
are distributed on the mucous surface. The arteries of the cutaneous set anas-
tomose with the arteries of the mucous set by minute branches which penetrate
the drum membrane near its margin. The superficial veins open into the external
jugular; those on the mucous surface drain themselves partly into the lateral
sinus and veins of the dura and partly into a plexus on the Eustachian tube.
1168
THE ORGANS OF SPECIAL SENSE
The outer surface of the drum membrane receives its nerve supply from the
auriculo-temporal branch of the inferior maxillary and the auricular branch of
the vagus. The inner surface is supplied by the tympanic branch of the glosso-
pharyngeal.
There are two sets of lymphatics, the cutaneous and mucous, which freely
communicate. The spaces between the dendritic fibres of Griiber are lymph-
spaces (Kessel).
The Ossicles of the Tympanum (Ossicula Auditus) (Fig. 776).
The tympanum contains in its upper part a chain of movable bones, three in
number, the malleus, incus, and stapes. The first is attached to the membrana
tympani, the last to the fenestra ovalis. The
incus is placed between the two, and is con-
nected to both by delicate articulations.
The Malleus or Hammer (Fig. 777).— The
malleus or hammer, so named from its fancied
resemblance to a hammer, is placed farthest in
front and outward. It consists of a head, neck,
and three processes — the handle or manubrium,
the processus gracilis, and the processus brevis.
The Head (capitulum mallei}. — The head is
the large upper extremity of the bone, and is
situated in the epitympanic recess (Fig. 774).
It is oval in shape, and articulates posteriorly
with the incus, being free in the rest of its ex-
tent. The facet for articulation with the incus
is covered with cartilage, is constricted near
the middle, and is divided by a ridge into an
upper, larger, and a lower, lesser part, which
form nearly a right angle with each other. Op-
posite the constriction the lower margin of the
facet projects in the form of a process, the
FIG. 776. — Chain of ossicles and their hga- J £
ments, seen from the front in a vertical, trans- COg-tOOth Or SpUT 01 the malleUS. On the back
verse section of the tympanum. (Testut.) » ,1 i i i i • , / • ,
oi the head below the spur is a crest (crista
mallei), to which the posterior ligament of the malleus is attached.
The Neck (collum mallei). — The neck is the narrow contracted part just beneath
the head; and below this is a prominence, to which the various processes are
attached. The outer surface of the neck faces the membrana flaccida. The
chorda tympani nerve crosses the inner surface (Fig. 774).
The Handle or Manubrium (manubrium mallei).— The manubrium is a vertical
process of bone, which is connected by its outer margin with the fibrous layer of
the membrana tympani, its entire length being fastened to the fibrous layer of
the drum membrane by its own periosteum and by a layer of cartilage (Griiber)
(Figs. 774 and 776). It is directed downward, inward, and backward; it decreases
in size toward its extremity, where it is curved slightly forward, and is flattened
from within outward. The handle forms a variable angle with the head of the
hammer. It averages about 130 degrees, but is always greater in the right ear
than in the left. It forms an angle with the horizontal, averaging on the right
side 50 degrees and on the left side 45 degrees (Spalteholz). Internally the
handle is covered by the mucous membrane of the tympanum. On the inner
side, near its upper end, is a slight projection, into which the tendon of the
Tensor tympani is inserted (Fig. 774).
The Processus Gracilis or Long Process (processus anterior [Folii\). — The pro-
cessus gracilis is a long and very delicate process, which passes from the front of
THE OSSICLES OF THE TYMPANUM
1169
the neck forward and outward to the Glaserian fissure, to which it is connected
by ligamentous fibres, constituting the broad ligament of Meckel. In the foetus
this is the longest process of the malleus, and is in direct continuity with the car-
tilage of Meckel.
The Processus Brevis (processus lateralis). — The processus brevis is a slight
conical projection, which springs from the root of the manubrium; it is directed
outward, and is attached to the upper part of the tympanic membrane by cartilage
and to the margins of the notch of Rivinus by the two malleolar folds.
SHORT ^H
PROCESS /
LONG
PROCESS
INSERTION
OF TENSOR
TYMPANI
MUSCLE
AURICULAR
SURFACE
FOR BODY
OF INCUS
INSERTION OF
EXTERNAL
LIGAMENT
OF MALLEUS
MANUBRIUM
FIG. 777. — The right malleus: a, viewed from in front; b, viewed from behind. (Spalteholz.)
The Incus or Anvil (Fig. 778). — The incus or anvil has received its name from
its supposed resemblance to an anvil, but it is more like a bicuspid tooth with two
roots, which differ in length, and are widely separated from each other. It con-
sists of a body and two processes. The body and the short process are placed in
the epitympanic recess (Fig. 776).
The Body (corpus incudis). — The body is somewhat quadrilateral, but compressed
laterally. On its anterior surface is a deeply concavo-convex facet, which articu-
lates with the head of the malleus, and the lower part is hollowed for the spur of the
malleus. In the fresh state the articular surface is covered with cartilage and the
joint is lined with synovial membrane.
ARTICULAR SURFACE
FOR HEAD OF MALLEUS
ARTICULAR
SURFACE FOR
HEAD OF
MALLEUS
LONG
PROCESS
LENTICULAR
PROCESS
FIG. 778. — The right incus: a, lateral view; b, medial and front view. (Spalteholz.)
Processes. — The two processes diverge from one another at an angle of from
90 to 100 degrees.
The Short Process (crus breve), somewhat conical in shape, projects nearly
horizontally backward, and articulates with a depression, the incus fossa (fossa
incudig), in the lower and back part of the epitympanic recess.
The Long Process (crus longum), longer and more slender than the preceding,
descends nearly vertically behind and parallel to the handle of the malleus, and,
1170 THE ORGANS OF SPECIAL SENSE
bending inward, terminates in a rounded globular projection, the os orbiculaxe or
lenticular process (processus lenticular -is) , which is tipped with cartilage, and articu-
lates with the head of the stapes. In the fretus the os orbiculare exists as a separate
bone.
The Stapes or Stirrup (Fig. 779). — The stapes or stirrup, so called from its
close resemblance to a stirrup, consists of a head, neck, two crura, and a base.
The Head (capitulum stapedis). — The head presents a depression, tipped with
cartilage, which articulates with the os orbiculare.
The Neck. — The neck, the constricted part of the bone succeeding the head,
receives the insertion of the Stapedius muscle.
The Crura. — The two crura (crus anterius and cms posterius) diverge from the
neck and are connected at their extremities by a flattened, oval-shaped plate, the
foot-plate or base (basis stapedis), which forms the foot-plate of the stirrup and
is fixed to the margin of the fei.estra ovalis by ligamentous fibres. The foot-
plate almost fills the oval window (Fig. 770). Of the two crura, the anterior is
shorter and less curved than the posterior. In a recent specimen a membrane will
be observed filling the space between the
crura and the foot-plate. This mem-
brane is connective tissue and is called
the membrana obturatoria stapedis. The
stirrup lies practically horizontal.
OBTURATOR
• MEMBRANE
<TEcRus-jf ^||_POSTERIOR "sssi*Fm Articulations of the Ossicles of the Tym-
panum (articulationes ossiculorum audi-
tus) (Fig. 776). — These small bones are
'*" OF.8T*P" connected with each other and with the
FIG. 779. — The right stirrup : a, viewed from above; 11 j> i i
b, medial vein. (Spaitehoiz.) walls or the tympanum by ligaments, and
are moved by small muscles. There is an
articulation between the head of the hammer and the body of the anvil ; one
between the os orbiculare of the anvil and the head of the stirrup; and there is a
syndesmosis between the margins of the oval window and the base of the stirrup.
The bones are fastened in the tympanum, • the handle of the hammer being
fastened in the drum membrane and the base of the stirrup to the oval window.
The articular surfaces of the malleus and incus and the orbicular process of the
incus and head of the stapes are covered with cartilage, connected together by
delicate capsular ligaments and lined by synovial membrane.
Ligaments Connecting the Ossicula with the Walls of the Tympanum (ligamenta
ossiculorum auditus). — The malleus is fastened to the wall of the tympanum by
three ligaments: the anterior, superior, and external ligaments.
The Anterior Ligament of the Malleus (ligamentum mallei anterius) consists of
two parts, the band of Meckel and the anterior ligament of Helmholtz.
The band of Meckel is attached to the base of the processus gracilis and passes
through the Glaserian fissure to reach the spine of the sphenoid. It was formerly
described by Sommering as a muscle, and it was called the laxator tympani
muscle. It is now, however, believed by most observers to consist of ligamentous
fibres only.
The anterior ligament of Helmholtz extends from the anterior margin of the
notch of Rivinus to the anterior portion of the malleus, just above the processus
gracilis.
The Superior Ligament of the Malleus (ligamentum mallei superius) is a delicate
round bundle of fibres which descends perpendicularly from the roof of the epi-
tympanic recess to the head of the malleus. It is sometimes called the suspensory
ligament.
The External Ligament of the Malleus (ligamentum mallei laterale) is a triangular
plane of fibres passing from the posterior part of the notch in the tympanic ring
THE OSSICLES OF THE TYMPANUM 1171
to the crest of the malleus. The posterior portion of the external ligament is
sometimes called the posterior ligament of Helmholtz (ligamentum mallei posterius
[Helmholtzi]). The malleus rotates around an axis composed of the external and
anterior ligaments, hence these two ligaments constitute what Helmholtz called
the axis ligament of the malleus.
The incus is fastened to the wall of the tympanum by two ligaments, the poste-
rior and the superior.
The Posterior Ligament of the Incus (ligamentum incudis posterius) is a short,
thick, ligamentous band which connects the extremity of the short process of the
incus to the posterior and lower part of the epitympanic recess, near the margin
of the opening of the mastoid cells.
A Superior Ligament of the Incus (ligamentum incudis superius) has been
described by Arnold, but it is little more than a fold of mucous membrane.
The inner surface and the circumference of the base of the stapes are covered with
hyaline cartilage, and the annular ligament of the stapes (ligamentum annulare baseos
stapedis) connects the circumference of the base to the margin of the fenestra ovalis.
The Muscles of the Tympanum (m. ossiculorum auditus). — The muscles of the
tympanum are two:
Tensor tympani. Stapedius.
The Tensor Tympani (m. tensor tympani} (Fig. 775), the larger, is contained in
the bony canal above the osseous portion of the Eustachian tube, from which it
is separated by the processus cochleariformis. It arises from the under surface of
the petrous bone, from the cartilaginous portion of the Eustachian tube, and from
the osseous canal in which it is contained. Passing backward through the canal,
it terminates in a slender tendon which enters the tympanum and makes a sharp
bend outward around the extremity of the processus cochleariformis, and is
inserted into the handle of the malleus near its root. Its nerve-supply is from
the motor root of the trigeminal nerve by way of the otic ganglion.
The Stapedius (m. stapedius) (Fig. 775) arises from the side of a conical cavity
hollowed out of the interior of the pyramid ; its tendon emerges from the orifice
at the apex of the pyramid, and, passing forward, is inserted into the neck of the
stapes. Its surface is aponeurotic, its interior fleshy, and its tendon occasionally
contains a slender bony spine, which is constant in some mammalia. It is
supplied by the tympanic branch of the facial nerve.
Actions. — The Tensor tympani draws the handle of the malleus inward and
thus heightens the tension of the drum membrane. It also causes slight rotation
of the bone around its long axis. When the Stapedius contracts it draws the
head of the stirrup backward, and in consequence the anterior end of the foot-
plate passes outward toward the tympanum, and the posterior end inward toward
the vestibule, and the annular ligament is made tense.
Movements of the Ossicles of the Tympanum. — The chain of bones is a lever-like
arrangement, by means of which the vibrations of the membrana tympani are
transferred to the membrane covering the oval window, and from this to the peri-
lymph in the labyrinth. When the drum membrane moves inward, the handle
of the malleus moves with it. The movement of the malleus moves the incus, and
the movement of the incus drives the foot of the stapes toward the labyrinth.
When the handle of the malleus moves inward, the spur on the head becomes
locked with the body of the incus. During outward movement it is unlocked.
The ordinary outward movement of the drum membrane causes the above-
described movements to be reversed. When there is overforcible outward move-
ment the incus does not go outward quite as far as the malleus, but slides at the
joint between the malleus and incus. This reluctance of the incus saves the foot
of the stapes from being pulled away from the oval window.
1172 THE ORGANS OF SPECIAL SENSE
The Mucous Membrane of the Tympanum (tunica mucosa tympanicd). — The
mucous membrane of the tympanum is continuous with the mucous membrane
of the naso-pharynx through the Eustachian tube, and is firmly united to the
periosteum. It invests the ossicula, and the muscles and nerves contained in the
tympanic cavity; forms the internal layer of the membrana tympani, and the outer
layer of the membrana tympani secundaria, and is reflected into the mastoid
antrum and air-cells, which it lines throughout. It forms several vascular folds
(plicae), which extend from the walls of the tympanum to the ossicles. In these
folds the ossicles are enveloped.
The anterior malleolar fold (plica malleolaris anterior) comes off from the mem-
brana tympani between the anterior edge of the notch of Rivinus and the handle
of the malleus, envelops the processus gracilis of the malleus, the anterior liga-
ment of the malleus, and the anterior portion of the chorda tympani nerve, and
terminates in a free concave edge (Spalteholz). The posterior malleolar fold (plica
malleolaris posterior) is the larger of the two. It comes off from the margin of the
notch of Rivinis, envelops the external ligament of the malleus, the posterior part
of the chorda tympani nerve, is attached to the handle of the malleus, and ends
in a free concave margin (Spalteholz). The fold of the incus (plica incudis) takes
origin from the roof of the epitympanic recess and passes to the body and short
process of the incus; and a similar fold passes from the head of the malleus to the
anterior wall of the epitympanic recess. The entire stapes, with its obturator
membrane, is enwrapped by the fold of the stapes (plica stapedis). This fold also
ensheaths the tendon of the stapedius muscle and often reaches to the posterior
wall of the cavity of the tympanum. The mucous membrane over the round
window forms the membrana tympani secundaria. These folds separate off pouch-
like cavities, and give the interior of the tympanum a somewhat honey-comb
appearance. One of these pouches is well marked — viz., the pouch of Prussak,
which lies between the neck of the malleus and the membrana flaccida.
The inferior external pouch of the tympanum or the pouch of Prussak (recessus
membranae tympani superior) is between the flaccid portion of the membrana
tympani, the external ligament of the malleus, and the neck of the mal-
leus. The anterior and posterior malleolar folds with the tympanic membrane
form two pouches. These are the anterior and posterior pouches or recesses of
Trbltsch (recessus membranae tympani, anterior and posterior) . The anterior pouch
is blind above and has a slit-like opening below. The posterior pouch is con-
tinued into the blind superior pouch of the drum membrane. In the tympanum
this membrane is pale, thin, slightly vascular, and covered for the most part with
columnar ciliated epithelium, but that covering the pyramid, ossicula, and mem-
brana tympani possesses a flattened, non-ciliated epithelium. In the antrum and
mastoid cells its epithelium is also non-ciliated. In the osseous portion of the
Eustachian tube the membrane is thin; but in the cartilaginous portion it is very
thick, highly vascular, covered with ciliated epithelium, and provided with numer-
ous mucous glands.
The Arteries of the Tympanum. — The arteries supplying the tympanum are six
in number. Two of them are larger than the rest — viz., the tympanic branch of
the internal maxillary, which enters by way of the Glaserian fissure and supplies
the membrana tympani ; and the stylo-mastoid branch of the posterior auricular,
which passes through the stylo-mastoid foramen and the aqueduct of Fallopius,
and supplies the inner wall and floor of the tympanum, the mastoid cells, and
antrum and the Stapedius muscle. This vessel anastomoses around the drum
membrane with the tympanic. The medidural sends a small branch to the Tensor
tympani muscle near its origin. The petrosal branch of the medidural enters the
tympanum by way of the hiatus Fallopii. Minute branches from the posterior
branch of the medidural pass through the petro-squamous fissure and are dis-
THE INTERNAL EAR OR LABYRINTH 1173
tributed to the antrura and epitympanic recess (Cunningham). Two tympanic
branches come oft' from the internal carotid artery in its course through the carotid
canal. A branch from the ascending pharyngeal and another from the Vidian
accompany the Eustachian tube. The two tympanic branches from the internal
carotid are given off in the carotid canal and perforate the thin anterior wall of the
tympanum.
The Veins of the Tympanum. — The veins of the tympanum terminate in the
ptervgoid plexus, the medidural vein, and the superpetrosal sinus.
The Nerves of the Tympanum. — The nerves of the tympanum constitute the
tympanic plexus (plexus tympanicus [Jacobsoni]) , which ramifies upon the surface
of the promontory (Fig. 775). The plexus is formed by (1) the tympanic branch of
the glosso-pharyngeal ; (2) the small deep petrosal nerve; (3) the small super-
ficial petrosal nerve; and (4) a branch which joins the great superficial petrosal.
The Tympanic Branch of the Glosso-pharyngeal or Jacobson's Nerve (n. tympan-
icus) enters the tympanum by an aperture in its floor close to the inner wall and
divides into branches, which ramify on the promontory and enter into the forma-
tion of the plexus. The small deep petrosal nerve (n. petrosus profundus), from
the carotid plexus of the sympathetic, passes through the wall of the carotid canal,
and joins the branches of Jacobson's nerve. The branch to the great superficial
petrosal passes through an opening on the inner wall of the tympanum in front
of the fenestra ovalis. The small superficial petrosal nerve (n. petrosus super-
ficialis minor), derived from the otic ganglion, passes through a foramen in the
middle fossa of the base of the skull (sometimes through the foramen ovale),
passes backward and enters the petrous bone through a small aperture, situ-
ated external to the hiatus Fallopii on the anterior surface of this bone; it then
courses downward through the bone, and, passing by the gangliform enlargement
of the facial nerve, receives a connecting filament from it (Fig. 779) and enters the
tympanic cavity, where it communicates with Jacobson's nerve, and assists in
forming the tympanic plexus.
The branches of distribution of the tympanic plexus are distributed to the
mucous membrane of the tympanum; one special branch passing to the fenestra
ovalis, another to the fenestra rotunda, and a third to the Eustachian tube. The
small superficial petrosal may be looked upon as a branch from the plexus to the
otic ganglion.
In addition to the tympanic plexus there are the nerves supplying the muscles.
The Tensor tympani is supplied by a branch from the third division of the tri-'
geminal through the otic ganglion, and the Stapedius by the tympanic branch of
the facial.
The chorda tympani (Figs. 771 and 774) crosses the tympanic cavity. It is given
off from the facial as it passes vertically downward at the back of the tympanum,
about a quarter of an inch before its exit from the stylo-mastoid foramen. It passes
from below upward and forward in a distinct canal, and enters the cavity of the
tympanum through an aperture, iter chordae posterius, already described (p. 1161),
and becomes invested with mucous membrane. It passes forward, through the
cavity of the tympanum, crossing internal to the membrana tympani and over
the handle of the malleus to the anterior inferior angle of the tympanum, and
emerges from that cavity through the iter chordae anterius or canal of Huguier
(p. 1 162). It is invested by the fold of mucous membrane already mentioned, and
therefore lies between the mucous and fibrous layers of the membrana tympani.
THE INTERNAL EAR OR LABYRINTH (AURIS INTERNA).
The internal ear is the essential part of the organ of hearing, receiving the
ultimate distribution of the auditory nerve. It is called the labyrinth, from the
1174 THE ORGANS OF SPECIAL SENSE
complexity of its shape, and consists of two parts: the osseous labyrinth, a series
of cavities channelled out of the substance of the petrous bone, and the membranous
labyrinth, the latter being contained within the former.
The Osseous Labyrinth (Labyrinthus Osseus) (Fig. 780).
The osseous labyrinth consists of three parts: the vestibule, semicircular canals,
and cochlea. These are cavities hollowed out of the substance of the bone, and
lined by periosteum. A clear fluid is contained in the space between the osseous
labyrinth and the membranous labyrinth. The space is called the perilymph
space, and the fluid is called perilymph or liquor Cotunnii.
The Vestibule (vestibulum) (Figs. 776 and 780). — The vestibule is the common
central cavity of communication between the parts of the internal ear. It is situated
on the inner side of the tympanum, behind the cochlea, and in front of the semi-
circular canals. It is somewhat ovoidal in shape from before backward, flattened
from within outward, and measures about one-fifth of an inch from before back-
of aqueductus vestibuli.
Bristle passed through foramen rotundum.
Opening of aqueductus cochleae.
FIG. 780. — The osseous labyrinth laid open (enlarged).
ward, as well as from above downward, and about one-eighth of an inch from with-
out inward. On its outer or tympanic wall is the fenestra ovalis (fenestm vestibuli),
closed, in the recent state, by the base of the stapes, and its annular ligament.
On its inner wall, at the forepart, is a small circular depression, fovea hemi-
sphaerica or spherical recess (recessus spliaericus] , in which the saccule is placed.
This recess is perforated, at its anterior and inferior part, by about a dozen minute
holes (macula cribrosa media], for the passage of filaments of the auditory nerve
to the saccule. Above and behind this depression is an oblique ridge, the crista
vestibuli. The anterior extremity of the crista vestibuli is the shape of a triangle,
and is called the pyramid (pyramis vestibuli}. This ridge bifurcates posteriorly to
enclose a small depression, the recessus cochlearis of Reichert, which is perforated
by eight small holes for the passage of filaments of the auditory nerve which
supply the posterior end of the ductus cochlearis. An oval depression is placed
in the roof and inner wall of the vestibule above and behind the crista vestibuli.
It is called the fovea hemielliptica, elliptical recess or spherical recess (recessus
ellipticus], and receives the utricle. The pyramid and the adjacent elliptical
recess are perforated by numerous minute foramina (macula cribrosa superior],
THE OSSEOUS LABYRINTH 1175
The openings in the pyramid transmit filaments from the vestibular nerve to the
utricle; the openings in the elliptical recess transmit filaments from the vestibular
nerve to the ampullae of the superior and external semicircular canals. Below and
behind the elliptical recess is a groove which deepens into a canal and is called
the aquaeductus vestibuli. This canal passes to the posterior surface of the petrous
portion of the temporal bone and opens as a mere crack between the internal
auditory meatus and the groove for the lateral sinus. It transmits a small vein,
and contains a tubular prolongation of the lining membrane of the vestibule,
the ductus endolymphaticus, which ends in a cul-de-sac between the layers of the
dura within the cranial cavity. Behind, the semicircular canals open into the
vestibule by five orifices. In front is an elliptical opening, which communicates
with the scala vestibuli of the cochlea by an orifice, apertura scalae vestibuli cochleae.
This opening is bounded below by a thin plate of bone (lamina spiralis ossea),
which takes origin from the vestibular floor external to the spherical recess and
in the cochlea forms the bony portion of the partition between the scala tympani
and the scala vestibuli. In the anterior portion of the vestibular floor is a fissure
(fissiira vestibuli), which passes into the bony part of the canal of the cochlea.
The external boundary of this fissure is a small, thin plate of bone (lamina spiralis
secundaria).
The Semicircular Canals (canales semicirculares ossei) (Fig. 780) . — The semi-
circular canals are three bony canals situated above and behind the vestibule. They
are of unequal length, compressed from side to side, and each describes the greater
part of a circle. They measure about one-twrentieth of an inch in diameter, and
each presents a dilatation at one end, called the ampulla ossea, which measures
more than twice the diameter of the tube. These canals open into the vestibule
by five orifices, one of the apertures being common to two of the canals.
The Superior Semicircular Canal (canalis semicircularis superior). — The superior
semicircular canal is vertical in direction, and is placed transversely to the long
axis of the petrous portion of the temporal bone, on the anterior surface of which
its arch forms a round projection. It describes about two-thirds of a circle. Its
outer extremity, which is ampullated, communicates by a distinct orifice with the
upper part of the vestibule; the opposite end of the canal, which is not dilated,
joins with the corresponding part of the posterior canal to form the cms commune,
which opens into the upper and inner part of the vestibule.
The Posterior Semicircular Canal (canalis semicircularis posterior). — The posterior
semicircular canal, also vertical in direction, is directed backward, nearly parallel
to the posterior surface of the petrous bone ; it is the longest of the three ; its ampul-
lated end commences at the lower arid back part of the vestibule, its opposite end
joining to form the common canal already mentioned. In the wall of the ampulla
of the posterior canal are a number of small openings (macula cribrosa inferior)
for the entrance of nerves to the ampulla.
The External or Horizontal Canal (canalis semicircularis lateralis). — The external
or horizontal canal is the shortest of the three, its arch being directed outward and
backward; thus each semicircular canal stands at right angles to the other two.
Its ampullated end corresponds to the upper and outer angle of the vestibule, just
above the fenestra ovalis, where it opens close to the ampullary end of the superior
canal; its opposite end opens by a distinct orifice at the upper and back part of the
vestibule.
The Cochlea (Figs. 780,78 1,782, and 783) .—The cochlea bears some resemblance
to a common snail-shell ; it forms the anterior part of the labyrinth, is conical in form,
and placed almost horizontally in front of the vestibule; its apex is directed forward
and outward, with a slight inclination downward, toward the upper and front part
of the inner wall of the tympanum ; its base corresponds with the anterior depression
at the bottom of the internal auditory meatus, and is perforated by numerous
1176
THE ORGANS OF SPECIAL SENSE
apertures for the passage of the cochlear divisions of the auditory nerve. It meas-
ures nearly a quarter of an inch (5 mm.) from base to apex, and its breadth across
Fio. 781. — Osseous cochlea in vertical section. The broken, white lines indicate the position of the basilar
membrane of the canal of the cochlea. Semidiagrammatic. (Testut.) •
the base is somewhat greater (about 9 mm.). It consists of a conical-shaped
central axis, the modiolus or'columella ; of a canal, the bony canal of the cochlea, the
inner wall of which is formed by the central axis, wound spirally around it for two
TRACTUS
SPIRALIS
FORAMINOSUS
AREA
COCHLEAE
COMPACT BONY
CANAI.IS CANALIS LON- SUBSTANCE OF
BASIS SPIRALIS GITUDINALIS CAPSULE OF SULCUS FOR LA RGE SUPER-
MODIOLI MODIOLI MODOLI LABYRINTH /FICIAL PETROSAL N ERV E
LAMINA MODIOLI
SULCUS FOR SMALL SUPER-
FICIAL PETROSAL NERVE
SEMICANAL
.FOR TENSOR
TV M PAN I
MUSCLE
GLASERIAN
FISSURb
SEMICANAL OF
EUSTACHIAN
TUBE
LAMINA
SPIRALIS
OSSEA
LAMINA SPIRALIS
SECUNDARIA
FIG. 782. — Vertical section through the right cochlea, medial portion, viewed from the lateral side. (Spalteholz.)
turns and three-quarters, from the base to the apex, and of a delicate lamina, the
lamina spkalis ossea, which projects from the modiolus, and, following the windings
THE OSSEO US LAB YRINTH \ \ 77
of the canal, partially subdivides it into two. In the recent state certain mem-
branous layers are attached to the free border of this lamina, which project into
the canal and completely separate it into two passages, which, however, com-
municate with each other at the apex of the modiolus by a small opening, named
the helicotrema.
The Modiolus (Figs. 782 and 783). — The modiolus or columella is the central axis
or pillar of the cochlea. It is conical in form, and extends from the base to the apex
of the cochlea. Its base (basis modioli] is broad, and appears at the bottom of the
internal auditory meatus, where it corresponds with the area cochleae. It is per-
forated by numerous orifices, which transmit filaments of the cochlear division
of the auditory nerve, the nerves for the first turn and a half being transmitted
through the foramina of the tractus spiralis foraminosus; the fibres for the apical
turn passing up through the foramen centrale. The foramina of the tractus
spiralis foraminosus pass up through the modiolus and successively bend out-
ward to reach the attached margin of the lamina spiralis ossea. Here they become
enlarged, and by their apposition form a spiral canal (canalis spiralis modioli),
which follows the course of the attached margin of the lamina spiralis ossea and
lodges the ganglion of Corti (ganglion spirale cochleae). The foramen centrale is
continued as a canal up the middle of the modiolus to its apex, and from this canal
numerous minute foramina pass outward to the unattached edge of the lamina
spiralis. In the foramina are vessels and nerves. The axis diminishes rapidly
in size in the second and succeeding coil.
FIG. 783. — The cochlea laid open (enlarged).
The Bony Canal or the Spiral Canal of the Cochlea (canalis spiralis cochleae) (Fig.
783). — The bony canal of the cochlea takes two turns and three-quarters round the
modiolus. The first turn of the canal is called the basal coil, the second is called the
central coil, the third turn is called the apical coil. The promontory on the inner wall
of the tympanic cavity is caused by the basal coil. The bony canal of the cochlea is
a little over an inch in length (about 30 mm.), and diminishes gradually in size from
the base to the summit, where it terminates in a cul-de-sac, the cupola (cupula), which
forms the apex of the cochlea. The commencement of this canal is about the
tenth of an inch in diameter; it diverges from the modiolus toward the tympanum
and vestibule, and presents three openings. One, the fenestra rotunda, commu-
nicates with the tympanum ; in the recent state this aperture is closed by a mem-
brane, the membrana tympani secundaria. Another aperture, of an elliptical form,
enters the vestibule. The third is the aperture of the aquaeductus cochleae, leading
to a minute funnel-shaped canal, which opens on the basilar surface of the petrous
bone internal to the jugular fossa, and transmits a small vein, and also forms
a communication between the subarachnoidean space of the skull and the peri-
lymph contained in the scala tympani.
The Lamina Spiralis Ossea. — The lamina spiralis ossea is a bony shelf or ledge
which projects outward from the modiolus into the interior of the spiral canal,
1178
THE ORGANS OF SPECIAL SENSE
and, like the canal, takes two and three-quarter turns around the modiolus. It
reaches about half-way toward the outer wall of the spiral tube, and partially
divides its cavity into two passages or scalae, of which the upper is named the
scala vestibuli, while the lower is termed the scala tympani. Near the summit of
the cochlea the lamina terminates in a hook-shaped process, the hamulus (hamulus
laminae spiralis), which assists in forming the boundary of a small opening, the
helicotrema, by which the two scalae communicate with each other. From the
canalis spiralis modioli numerous foramina pass outward through the osseous
spiral lamina as far as its outer or free edge. In the lower part of the first turn
a second bony lamina (lamina spiralis secundaria) projects inward from the
outer wall of the bony tube; it does not, however, reach the primary osseous spiral
lamina, so that if viewed from the vestibule a narrow fissure, the fissura vestibuli,
is seen between them.
The membrana basilaris (Fig. 781) is stretched from the unattached edge of
the lamina spiralis ossea to the outer wall of the cochlea. The lamina spiralis
NERVE OF AMPULLA
OFSUPCRIOR CANAL
AMPULLA OF SUPERIOR
MEMBRANOUS CANAL
SUPERIOR
TERMINAL
BRANCH OF
VESTIBULAR
NERVE
OUCTUS
COCHLEARIS
COCHLEAR
NERVE
ACOUSTIC
NERVE
VESTIBULAR
NERVE
VCSTIBULAR
GANGLION
DUCT OF
SUPERIOR
SEMICIRCULAR
CANAL
AMPULLA OF
EXTERNAL
MEMBRANOUS
CANAL
DUCT OF
EXTERNAL
SEMICIRCULAR
CANAL
CRUS
COMMUNE
DUCT OF
POSTERIOR
SEMICIRCULAR
CANAL
DUCTUS EN DO.
LYMPHATICUS
NERVE OF NERVE OF AMPULLA SACCULE AM PU LLA OF POSTERIOR
SACCULE OF POSTERIOR CANAL MEMBRANOUS CANAL
FIG. 784. — The right membranous labyrinth of an adult, isolated, medial and posterior view. (Spalteholz.)
makes an incomplete septum between the scala tympani and scala vestibuli; the
membrana basilaris completes the septum. Even with the perfected septum the
two scalae communicate at the apex of the cochlea by means of the helicotrema.
The Fundus of the Internal Auditory Meatus (fundus meatus acustici interni) . —
This structure is the inner wall of the vestibule and the base of the modiolus. A
transverse ridge (crista transversa) maps it off into two parts, the fossula superior
and the fossula inferior. The facial area (area n. facialis) is in the anterior portion
of the fossula superior. The opening seen here is the beginning of the aqueduct
of Fallopius (canalis facialis) for the transmission of the facial nerve. The superior
area of the vestibule (area vestibularis superior) is the posterior portion of the fossula
superior. Here the nerves perforate which supply the utricle and the ampullae of
the superior and external semicircular canals (Cunningham). The area cochleae
is the anterior portion of the fossula inferior. In it is the canalis centralis for the
nerve-fibres to the apical turn of the cochlea; and the tractus spiralis foraminosa
for the transmission of nerves to the first turn and a half of the cochlea. The
THE MEMBRANOUS LABYRINTH
1179
inferior area of the vestibule (area vestibularis inferior] is back of the area cochleae
and a ridge separates the two. It transmits nerves to the saccule. At the posterior
part of the fossula inferior is a solitary foramen, the foramen singulare, which
transmits nerves to the ampulla of the posterior semicircular canal.
The Membranous Labyrinth (Labyrinthus Membranaceus) (Figs. 784, 785).
The membranous labyrinth is contained within the bony cavities just described,
having the same general form as the cavities in which it is contained, though
considerably smaller, being separated from the bony walls by a quantity of fluid,
the perilymph or liquor Cotunnii (perilympha). It does not, however, float loosely
in this fluid, but in places is fixed to the walls of the cavity. The membranous
sac contains fluid, the endolymph (endolympha) , and on the sac the ramifications
of the auditory nerve are distributed.
Within the osseous vestibule the membranous labyrinth does not quite preserve
the form of the bony cavity, but presents two membranous sacs, the utricle and
the saccule.
_ Ductus
~Endolymphaticus
FIG. 785. — The membranous labyrinth (enlarged).
The Utricle (utriculus). — The utricle is the larger of the two, of an oblong
form, compressed laterally, and occupies the upper and back part of the vestibule,
lying in contact with the fovea semi-elliptica and the part below it. The highest
portion of the utricle is called the recess (recessus utriculi); it is placed in the
elliptical recess, and opening into it are the ampulla of the superior and external
semicircular canals. The central portion of the recess of the utricle receives upon
the side the external semicircular canal. This opening has not an ampulla. The
superior sinus is a prolongation upward and backward from the central portion of
the utricle and in the superior sinus the crus commune and the superior and
posterior semicircular canals open. The lower and inner portion of the utricle
is the inferior sinus, and into it the ampulla of the posterior semicircular canal
opens. The floor and anterior wall of the recess of the utricle are much thicker
than elsewhere, and form the macula acustica utriculi, which receives the utricular
filaments of the auditory nerve and has attached to its internal surface a layer of
calcareous particles which are called otoliths. The cavity of the utricle communi-
cates behind with the membranous semicircular canals by five orifices. From
its anterior wall is given off a small canal (ductus utriculosaccularis) , which joins
with a canal from the saccule, the ductus endolymphaticus. The utricle is joined
to the bony wall by numerous fibrous bands.
1180 THE ORGANS OF SPECIAL SENSE
The Saccule (sacculus). — The saccule is the smaller of the two vesicular sacs;
it is globular in form, lies in the elliptical recess near the opening of the scala
vestibuli of the cochlea. Its anterior part exhibits an oval thickening, the macula
acustica sacculi, to which are distributed the saccular filaments of the auditory
nerve. Its cavity does not directly communicate with that of the utricle. From
the posterior wall is given off a canal, the ductus endolymphaticus. This duct
passes along the aquaeductus vestibuli and ends in a blind pouch on the posterior
surface of the petrous portion of the temporal bone, where it is in contact with
the dura. The upper extremity of the saccule looks upward and backward
and forms the sinus utricularis sacculi. This lies in contact with but is not a
part of the wall of the utricle. The vestibule contains the closed end of the
ductus cochlearis. This is known as the caecum vestibulare. The ductus coch-
learis lies below the saccule in what Reichert described as the recessus cochlearis,
and it enters the spiral canal. From the lower part of the saccule a short tube,
the canalis reunions of Hensen (ductus reuniens [Henseni]), passes downward
and outward to open into the ductus cochlearis. The saccule is held in posi-
tion by numerous fibrous bands which pass between the saccule and the bony
wall.
The Membranous Semicircular Canals (ductus semicircular es}. — The mem-
branous semicircular canals are about one-third the diameter of the osseous canals,
but in number, shape, and general form they are precisely similar, and present
at one end within the osseous ampulla a membranous ampulla. These ampullae
are called ampullae membranaceae. The canals open by five orifices into the utricle,
one opening being common to two canals. In the ampullae the wall is thickened,
and projects into the cavity as a fiddle-shaped, transversely placed elevation, the
septum trans versum, in which the nerves end.
The membranous canals are attached here and there to the bone by numerous
fibrous bands, the so-called ligaments (ligamenta labyrinthi canaliculorum) .
Structure. — The walls of the utricle, saccule, arid membranous semicircular
canals consist of three layers. The outer layer is a loose and flocculent struc-
ture, apparently composed of ordinary fibrous tissue, containing blood-vessels
and pigment-cells analogous to those in the pigment coat of the retina. The
middle layer, thicker and more transparent, bears some resemblance to the
hyaloid membrane, but it presents on its internal surface, especially in the semi-
circular canals, numerous papilliform projections, and, on the addition of acetic
acid, presents an appearance of longitudinal fibrillation and elongated nuclei.
The inner layer is formed of polygonal nucleated epithelial cells. The raphe of
each semicircular canal is a line upon the concave side of the canal. Along the
raphe the height of the epithelial cells is distinctly increased. In the ampullae
adjacent to the cristae acusticae the cells are cylindrical and constitute the
plana semilunata. In the maculae of the utricle and saccule, and in the trans-
verse septa of the ampullae of the canals, the middle coat is thickened and the
epithelium is columnar, is increased in height, and passes into the neuro-epithe-
lium. The neuro-epithelium consists of supporting cells and hair-cells.
1. The supporting cells are long, wider at the ends than in the centre, contain an
oval nucleus, and the lower end of the cell is fissured.
2. The hair-cells are columnar, with bulged lower ends and free upper ends.
The bulged lower ends, each of which contains a spherical nucleus, do not reach
higher than the middle of the epithelial layer. Each free upper end is surmounted
by a long, tapering filament. These filaments constitute auditory hair, and they
project into the cavity. The filaments of the auditory nerve enter these parts,
and, having pierced the outer and thickened middle layer, they lose their medul-
lary sheath, and their axis-cylinders divide into three or four branches at the
larger and deeper ends of the hair-cells. These branches form a horizontal plexus
THE MEMBRANOUS LABYRINTH
1181
(stratum plexi forme). "These surround the hair-cells like the calyx of a flower,
and give off ascending branches, which, however, do not reach the surface. In
this way one branch usually comes in contact with many hair-cells."1
FIG. 786. — Floor of scala media, showing the organ of Corti, etc.
Numerous small prismatic bodies termed statoliths, otokonien crystals or otoliths,
and consisting of a mass of minute crystalline grains of carbonate of lime, held
COCHLEAR NCRVE
AND GANGLION
FIG. 787. — Cochlea in transverse section. Observe especially the canal of the cochlea, which is a part of
the membranous labyrinth. (Testut.)
together in a rnesh of delicate fibrous tissue, are contained in the walls of the
utricle and saccule opposite the distribution of the nerves. The membrane is
1 Histology and Microscopic Anatomy. By Dr. Ladislaus Szymonowicz. Translated and edited by John
Bruce MacCallum, M.D.
1182 THE ORGANS OF SPECIAL SENSE
called the otolith membrane. A calcareous material is also, according to Bowman,
sparingly scattered in the cells lining the ampullae of the semicircular canals. The
conical thickening in the ampulla corresponds to the otolith membrane and is
called the cupola.
The Membranous Cochlea, Ductus Cochlearis or Scala Media consists of a spirally
arranged tube enclosed in the bony canal of the cochlea and lying along its outer
wall. It begins as a blind end in the recessus cochlearis of the vestibule. This
beginning is the caecum vestibulare. It ascends inside the bony cochlea and termi-
nates at the apex of the cochlea by a blind end, the lagena (caecum cupulare). The
manner in which it is formed will now be described.
The osseous spiral lamina, as above stated, extends only part of the distance be-
tween the modiolus and the outer bony wall of the cochlea. A membrane, the basilar
membrane (membrana basilaris) (Fig. 786) , stretches from its free edge to the outer
wall of the cochlea, and completes the roof of the scala tympani. A second and more
delicate membrane, the membrane of Reissner (membrana vestibularis [Reissneri])
(Fig. 786), extends from the thickened periosteum covering the lamina spiralis ossea
to the outer wall of the cochlea, to which it is attached at some little distance above
the membrana basilaris. A canal is thus shut off between the scala tympani below
and the scala vestibuli above; this is the membranous canal of the cochlea (ductus
cochlearis or scala media] (Fig. 787). It is triangular on transverse section, its roof
being formed by the membrane of Reissner, its outer wall by the periosteum which
lines the bony canal, and its floor by the membrana basilaris, and the outer part
of the lamina spiralis ossea, on the former of which is placed the organ of Corti.
Reissner's membrane is thin and homogeneous, and is covered on its upper and
under surfaces by a layer of epithelium. The periosteum, which forms the outer
wall of the ductus cochlearis, is greatly
NERVE-FIBRES PASSING OUT tViiVlr p>nf»rl nnrl altf>rf>rl in r>Viarnr>tfr
GANGLION SPIRAL BETWEEN TH E TWO LAY E RS O F 6F>
SPIRALS FIBRES LA M i NA spi R Ans ossE forming what is called the spiral liga-
ment of the cochlea (ligamentum spirale
cochleae) (Fig. 786) . It projects inward
below as a triangular prominence, the
Crista basilaris, which gives attach-
ment to the outer edge of the mem-
brana basilaris, and immediately above
which is a concavity, the sulcus spiralis
externus (Fig. 786). The upper por-
tion of the ligamentum spirale con-
FIG. 788. — Part of the cochlear nerve, highly magnified. . ... 1. ,
(Henie.) tains numerous capillary loops and
small blood-vessels, and forms what
is termed the stria vascularis. The stria is limited below by a prominence (promi-
nentia spiralis), in which a blood-vessel (vas prominens) is distinctly visible.
The lamina spiralis ossea (Fig. 787) consists of two plates of bone extending
outward; between these are the canals for the transmission of the filaments of the
auditory nerve. On the upper plate of that part of the osseous spiral lamina
which is outside Reissner's membrane the periosteum is thickened to form the
limbus laminae spiralis, and this terminates externally in a concavity, the sulcus
spiralis internus, which presents, on section, the form of the letter C; the upper
part of the letter, formed by the overhanging extremity of the limbus, is named
the labium vestibulare ; the lower part, prolonged and tapering, is called the labium
tympanicum, and is perforated by 4000 foramina (foramina nervosa) for the pass-
age of the cochlear nerves. Externally, the labium tympanicum is continuous
with the membrana basilaris. The upper surface of the labium vestibulare is
intersected at right angles by a number of furrows, between which are numerous
elevations; these present the appearance of teeth along the free margin of the
THE MEMBRANOUS LABYRINTH
1183
labium, and have been named by Huschke the auditory teeth. There are 7000
auditory teeth. The basilar membrane may be divided into two areas, inner and
outer. The inner is thin, and is named the zona arcuata or zona tecta (Fig. 786); it
supports the organ of Corti. The outer is thicker and striated, and is termed
the zona pectinata. The under surface of the membrane is covered by a layer of
Outer hair cells.
Membrana tectona.
Limbus.
Cells of Deiters.
Outer rod.
Basilar membrane.
FIG. 789. — Section through the organ of Corti. Magnified. (G. Retzius.)
-'--S.RaBrAtti
Nerve fibres.
vascular connective tissue. One of these vessels is somewhat larger than the rest,
and is named the vas spirale (Fig. 789); it lies below Corti's tunnel.
Organ of Corti1 (organon spirale [Cortii]) (Figs. 786, 787, 789, and 790).— The
inner part of the membrana basilaris — that is, the part directed toward the canal
of the ductus cochlearis — is covered with epithelium, which is largely neuro-epithe-
INTERNAL AUDI-
TORY CELLS
BASILAR MEMBRANE
FIG. 790. — Organ of Corti. Diagrammatic view of a small portion. (Testut.)
Hum.
nerve.
It forms the organ of Corti. In this lie the terminations of the cochlear
It appears at first sight as a papilla, winding spirally throughout the
whole length of the ductus cochlearis, from which circumstance it has been desig-
nated the papilla spiralis. More accurately viewed, it is seen to be composed
of a remarkable arrangement of cells, which may be likened to the keyboard of a
1 Corti's original paper is in the Zeitschrift f. Wissen. Zool., iii., 109.
1184
THE ORGANS OF SPECIAL SENSE
pianoforte. The organ of Corti consists of an inner part and an outer part. Each
part contains auditory cells and supporting cells. Of these cells, the two central
ones are rod-like bodies and are called the inner and outer rods of Corti. They are
placed on the basilar membrane, at some little distance from each other, but are
inclined toward each other, so as to meet at their opposite extremities, and form
a series of arches roofing over a minute tunnel, the canal or tunnel of Corti,
between them and the basilar membrane, which ascends spirally through the
whole length of the cochlea.
The inner rods (Fig. 789), some 6000 in number, are more numerous than the
outer ones, and rest on the basilar membrane, close to the labium tympanicum ;
they project obliquely upward and outward, and terminate above in expanded
extremities which resemble in shape the upper end of the ulna, with its sigmoid
cavity, coronoid and olecranon processes. On the outer side of the rod, in the
angle formed between it and the basilar membrane, is a nucleated mass of proto-
plasm; while on the inner side is a row of epithelial cells, inner hair-cells (Fig.
789), surmounted by a brush of fine, stiff, hair-like processes. On the inner side
of these cells are two or three rows of columnar supporting cells, which are
continuous with the cubical cells lining the sulcus spiralis internus.
FIG. 791. — Longitudinal section of the cochlea, showing the relations of the scalae, the ganglion spirale, etc.
S. V., Scala vestibuli. S. T., Scala tympani. S. M., Scala media. L. S., Ligamentum spirale. G. S., Ganglion
spirale.
The outer rods (Fig. 789), numbering about 4000, also rest by a broad foot on
the basilar membrane; they incline upward and inward, and their upper extremity
resembles the head and bill of a swan ; the back of the head fitting into the con-
cavity— the analogue of the sigmoid cavity — of one or more of the internal rods,
and the bill projecting outward as a phalangeal process of the membrana reticu-
laris, presently to be described.
In the head of these outer rods is an oval portion, where the fibres of which
the rod appears to be composed are deficient, and which stains more deeply with
carmine than the rest of the rod. At the base of the rod, on its internal side-
that is to say, in the angle formed by the rod with the basilar membrane— is a
similar protoplasmic mass to that found on the outer side of the base of the inner
rod; these masses of protoplasm are probably the undifferentiated portions of the
cells from which the rods are developed. External to the outer rod are three or
four successive rows of epithelial cells, more elongated than those found on the
THE MEMBRANOUS LABYRINTH 1185
internal side of the inner rod, but, like them, furnished with minute hairs-or cilia.
These are termed the outer hair-cells, in contradistinction to the inner hair-cells
above referred to. There are about 12,000 outer hair-cells, and about 3500 inner
hair-cells.
The hair-cells are somewhat oval in shape; their free extremities are on a
level with the heads of Corti's rods, and from each some twenty fine hairlets
project and are arranged in the form of a crescent, the concavity of which opens
inward. The deep ends of the cells are rounded and contain large nuclei; they
reach only as far as the middle of Corti's rods, and are in contact with the rami-
fications of the nervous filaments. Between the rows of the outer hair-cells
are rows of supporting cells, called the cells of Deiters; their expanded bases are
planted on the basilar membrane, while their opposite ends present a clubbed
extremity or phalangeal process. Immediately to the outer side of Deiters's cells
are some five or six rows of columnar cells, the supporting cells of Hensen. Their
bases are narrow, while their upper parts are expanded and form a rounded
elevation on the floor of the ductus cochlearis. The columnar cells lying outside
Hensen's cells are termed the cells of Claudius. A space is seen between the
outer rods of Corti and the adjacent hair-cells; this is called the space of Nuel.
The lamina reticularis or membrane of Kblliker is a delicate framework per-
forated by rounded holes. It extends from the inner rods of Corti to the external
row of the outer hair-cells, and is formed by several rows of "minute fiddle-
shaped cuticular structures " called phalanges, between which are circular
apertures containing the free ends of the hair-cells. The innermost row of phal-
anges consists of the phalangeal processes of the outer rods of Corti; the outer
rows are formed by the modified free ends of Deiters's cells.
Covering over these structures, but not touching them, is the membrana tectoria
or membrane of Corti (Figs. 786 and 789), which is attached to the vestibular sur-
face of the lamina spiralis close to the attachment of the membrane of Reissner.
It is thin near its inner margin, and overlies the auditory teeth of Husch'ke. Its
outer half is thick, and along its lower edge, opposite the inner hair-cells, is a
clear band, named Hensen's stripe. Externally, the membrane becomes much
thinner, and is attached to the outer row of Deiters's cells (Retzius).
The fibres from the cochlear nerve enter the organ of Corti as axis-cylinders,
which pass directly to the deepest portions of the inner and outer hair-cells by
way of the canal of Corti or by the space of Nuel. The terminations arborize
about the lower portions of the hair-cells and end on the surfaces of the hair-cells.
The inner surface of the osseous labyrinth is lined by an exceedingly thin fibro-
serous membrane, analogous to a periosteum, from its close adhesion to the
inner surfaces of these cavities, and performing the office of a serous membrane by
its free surface. It lines the vestibule, and from this cavity is continued into the
semicircular canals and the scala vestibuli of the cochlea, and through the helico-
trema into the scala tympani. A delicate tubular process is prolonged along the
aqueduct of the vestibule to the inner surface of the dura. This membrane is
continued across the fenestra ovalis and fenestra rotunda, and consequently has
no communication with the lining membrane of the tympanum. Its attached
surface is rough and fibrous, and closely adherent to the bone; its free surface is
smooth and pale, covered with a layer of epithelium, and secretes a thin, limpid
fluid, the aqua labyrinthi, liquor Cotunnii or perilymph (Blainville).
The scala media is closed above and below. The upper blind extremity is
termed the lagena, and is attached to the cupola at the upper part of the helico-
trema; the lower end is lodged in the recessus cochlearis of the vestibule. Near
this blind extremity, the scala media receives the canalis reunions of Hensen (Fig.
785), a very delicate canal, by which the ductus cochlearis is brought into con-
tinuity with the saccule.
1186 THE ORGANS OF SPECIAL SENSE
The Arteries of the Labyrinth. — The arteries of the labyrinth are the internal
auditory, from the basilar, and the stylo-mastoid, from the posterior auricular.
The internal auditory divides at the bottom of the internal auditory meatus
into two branches, cochlear and vestibular.
The cochlear artery divides into numerous minute branches, which enter
foramina in the tractus spiralis foraminosa and course in the lamina spiralis ossea
to reach the membranous structures. The largest of the cochlear branches is in
the canalis centralis.
The vestibular branches accompany the nerves, and supply the membranous
structures in the vestibule and semicircular canals. Two arteries go to each
canal. The two vessels enter opposite extremities of the canal, and anastomose
at the summit of the canal. The vestibular vessels form a minute capillary net-
work in the substance of each membranous labyrinth.
The Veins of the Labyrinth. — The veins of the vestibule and semicircular canals,
the auditory veins, accompany the arteries, and receive those of the cochlea at the
base of the modiolus, to form the internal auditory vein (vv. auditivae internae),
which opens into the posterior part of the inferior petrosal sinus or into the lateral
sinus.
The Nerves of the Labyrinth. — The auditory nerve (n. acusticus) , the special nerve
of the sense of hearing, divides, at the bottom of the internal auditory meatus,
into two branches, the cochlear and vestibular.
The Vestibular Nerve (n. vestibularis) , the posterior of the two, presents, as it lies
in the internal auditory meatus, a ganglion, the vestibular ganglion or the ganglion
of Scarpa (ganglion vestibulare) ; the nerve divides into three branches which pass
through minute openings at the upper and back part of the bottom of the meatus
(area vestibular posterior), and, entering the vestibule, are distributed to the utricle
and to the ampulla of the external and superior semicircular canals.
The nerve filaments enter the ampullary enlargements opposite the septum
transversum, and arborize around the hair-cells. In the utricle and saccule the
nerve-fibres pierce the membrana propria of the maculae, and end in arborizations
around the hair-cells.
The Cochlear Nerve (n. cochlearis) gives off the branch to the saccule, the fila-
ments of which are transmitted from the internal auditory meatus through the
foramina of the area vestibularis inferior, which lies at the lower and back part
of the floor of the meatus. It also gives off the branch for the ampulla of the
posterior semicircular canal, which leaves the meatus through the foramen singulare.
The rest of the cochlear nerve divides into numerous filaments at the base
of the modiolus; those for the basal and middle coils pass through the foramina
in the tractus foraminosus, those for the apical coil through the canalis centralis,
and the nerves bend outward to pass between the lamellae of the osseous spiral
lamina. Occupying the spiral canal of the modiolus is the spiral ganglion or gan-
glion of Corti (ganglion spirale), consisting of bipolar nerve-cells, which really con-
stitute the true cells of origin of this nerve, one pole being prolonged centrally to
the brain and the other peripherally to the hair-cells of Corti's organ. Reaching the
outer edge of the osseous spiral lamina, the nerve fibres pass through the foramina
in the labium tympanicum, where they lose their axis-cylinders. They enter the
organ of Corti and pass directly to the deep portions of the inner and outer hair-cells
by way of the canal of Corti and the space of Nuel. The terminations arborize
about the lower portions of the hair-cells and end in the surfaces of the cells.
Surgical Anatomy. — Malformations, such as imperfect development of the external parts,
absence of the meatus, or supernumerary auricles, are occasionally met with. Or the pinna may
present a congenital fistula, which is due to defective closure of the first visceral cleft, or rather
of that portion of it which is not concerned in the formation of the Eustachian tube, tympanum,
and meatus. In some cases the cephalo-auricular angle is almost absent; in others it is nearly
I HE MEMBRANOUS LABYRINTH 1187
a right angle. Projecting ears and long ears are said by some observers to be more common
among degenerates, criminals, and the insane than among the normal, the non-criminal, and
the sane. The skin of the auricle is thin and richly supplied with blood, but in spite of this it
is frequently the seat of frost-bite, due to the fact that it is much exposed to cold, and lacks the
usual underlying subcutaneous fat found in most other parts of the body. A collection of blood
is sometimes found between the cartilage and perichondrium (haematoma auris}, usually the
result of traumatism, but not necessarily due to this cause. It is said to occur most frequently
in the ears of the insane. Keloid sometimes grows in the auricle around the puncture made for
ear-rings, and epithelioma occasionally affects this part. Deposits of urate of soda are often met
with in the pinna in gouty subjects.
The external auditory meatus can be most satisfactorily examined by light reflected down a
funnel-shaped speculum; by gently moving the latter in different directions the whole of the
canal and membrana tympani can be brought into view. The points to be noted are: the pres-
ence of wax or foreign bodies, the size of the canal, and the condition of the membrana tympani.
The accumulation of wax is often the cause of deafness, and may give rise to very serious conse-
quences, causing ulceration of the membrane and even absorption of the bony wall of the canal.
Foreign bodies are not infrequently introduced into the ear by children, and, when situated in
the first portion of the canal, may be removed with tolerable facility by means of a minute hook
or loop of fine wire, the parts being illuminated with reflected light; but when they have slipped
beyond the narrow middle part of the meatus, their removal is in nowise easy, and attempts to effect
it, in inexperienced hands, may be followed by destruction of the membrana tympani and possibly
injury of the contents of the tympanum. The calibre of the external auditory canal may be nar-
rowed by inflammation of its lining membrane, running on to suppuration; by periostitis; by polypi,
sebaceous tumors, and exostoses. The membrana tympani, when seen in a healthy ear, "reflects
light strongly, and, owing to its peculiar curvature, presents a bright spot of triangular shape at its
lower and anterior portion." From the apex of this, proceeding upward and slightly forward, is
a white streak formed by the handle of the malleus, while near the upper part of the membrane
may be seen a slight projection, caused by the short process of the malleus. In disease alterations
in color, lustre, curvature or inclination, and perforation must be noted. Such perforations may
be caused by a blow, a loud report, a wound, or as the result of suppuration in the middle ear.
The upper wall of the meatus is separated from the cranial cavity by a thin plate of bone;
the anterior wall is separated from the temporo-mandibular joint and parotid gland by the bone
forming the glenoid fossa; and the posterior wall is in relation with the mastoid cells; hence
inflammation of the external auditory meatus may readily extend to the membranes of the brain,
to the temporo-mandibular joint, or to the mastoid cells; and, in addition to this, blows on the
chin may cause fracture of the wall of the meatus.
The nerves supplying the meatus are the auricular branch of the vagus, the auricula-temporal,
and the auricularis magnus. The connections of these nerves explain the fact of the occurrence,
in cases of any irritation of the meatus, of constant coughing and sneezing from implication of the
vagus, or of yawning from implication of the auriculo-temporal. No doubt also the association
of earache with toothache in cancer of the tongue is due to implication of the same nerve, a branch
of the trigeminal, which supplies also the teeth and the tongue. The vessels of the meatus and
membrana tympani are derived from the posterior auricular, temporal, and internal maxillary
arteries. The upper half of the membrana tympani is much more richly supplied with blood
than the lower half. For this reason, and also to avoid the chorda tympani nerve and ossicles,
incisions through the membrane should be made at the lower and posterior part.
The principal point in connection with the surgical anatomy of the tympanum is its relations
to other parts. Its roof is formed by a thin plate of bone, which, with the dura, is all that
separates it from the temporal lobe of the brain. Its floor is immediately above the jugular
fossa and the carotid canal, the fossa being behind and the canal in front. Its posterior wall pre-
sents the openings of the mastoid cells. On its anterior wall is the opening of the Eustachian
tube. Thus it follows that in disease of the middle ear we may get subdural abscess, septic
meningitis, or abscess of the cerebrum or cerebellum from extension of the inflammation through
the bony roof; thrombosis of the lateral sinus, with or without pyjemia, by extension through the
floor; or mastoid abscess by extension backward. In addition to this, we may get fatal hemorrhage
from the internal carotid in destructive changes of the middle ear; and in throat disease we may
get the inflammation extending up the Eustachian tube to the middle ear. The Eustachian tube
is accessible from the nose. If the nose and mouth be closed and an attempt made to expire air, a
sense of pressure with dulness of hearing is produced in both ears, from the air finding its way up
the Eustachian tube and bulging out the membrana tympani. During the act of swallowing, the
pharvngeal orifice of the tube, which is normally closed, is opened, probably by the action of
the Dilator tubea muscle. This fact was employed by Politzer in devising an easy method of
inflating the tube. The nozzle of an india-rubber syringe is inserted into the nostril; the patient
takes a mouthful of water and holds it in his mouth, both nostrils are closed with the finger and
thumb to prevent the escape of air, and the patient is then requested to swallow; as he does so the
1188
THE ORGANS OF SPECIAL SENSE
surgeon squeezes the bulb and the air is forced out of the syringe into his nose, and is driven into
the Eustachian tube, which is now open. The impact of the air against the membrana tympani
can be heard by the surgeon, if the membrane is intact, sound being conveyed by means of a
piece of india-rubber tubing, one end of which is inserted into the meatus of the patient's ear, the
other into that of the surgeon. The direct examination of the Eustachian tube is made by the
Eustachian catheter. This is passed along the floor of the nostril, close to the septum, with
the point touching the floor, to the posterior wall of the pharynx. When this is felt, the catheter
is to be withdrawn about half an inch, and the point rotated outward through a quarter of a
circle, and pushed again slightly backward, when it will enter the orifice of the tube, and will
be found to be caught, and air forced into the catheter will be heard impinging on the tympanic
membrane if the ears of the patient and surgeon are connected by an india-rubber tube.
THE SKIN (INTEGUMENTUM COMMUNE).
The skin covers the body surface and is continuous with the mucous membrane
at the origin and termination of the alimentary canal and at the openings of other
canals. The skin is a protective coat, a regulator of body-temperature, contains
multitudes of the terminations of sensor nerves, and is the seat of the organ of
touch (organon tactus). These nerve-terminations are connected with nerve-fibres of
temperature, pressure, and pain. Connected with the skin are sweat-glands which
have important excretory functions and sebaceous glands. From its superficial part
come appendages, the hairs, and nails. The skin is elastic and varies in thickness
from 0.5 mm. to 4 mm. It is thinnest in the eyelids and prepuce, and thickest over
the back of the neck, back of the shoulders, palms of the hands, and soles of the
feet. Its color depends in part on the blood within it, and in part upon pigment.
The deepest hue is about the anus, in the genital region, in the axillae, over the
mammary glands, and in the parts exposed to air, light, and varied temperatures.
The color varies with age, being pinkish in extreme youth and becoming yellow
in old age. It varies with exposure and with climate, being deepest in those who
;brave all weathers and temperatures and in those who dwell beneath a tropical sun.
It also varies with race, and this is
so well recognized that races are class-
ified by the color of the skin into the
Black, White, Yellow, and Brown races.
The color of the skin is also affected
in certain diseases; being extremely
pale in anaemia, brown in Addison's
disease, yellow in jaundice, etc.
In most situations the skin is mova-
ble, but in some it is attached closely
to underlying structures, and is con-
sequently immovable on the scalp,
the palms of the hands, the soles of
the feet, and the outer portion of the
pinna of the ear. The skin is fairly
smooth, but close examination dis-
closes multitudes of openings, creases,
furrows, depressions, folds, and hairs.
Hair-follicles open upon the surf ace,
and the ducts of sebaceous glands
and of sweat-glands perforate the skin.
About the joints are folds of skin (retinacula cutis), and temporary folds or
wrinkles are created by the contraction of superficial muscles. The facial wrinkles
of advancing years are due to habitual expression and loss of skin elasticity. A
dimple is a permanent pit or depression due to adhesion of the surface to parts
beneath. The ridges and furrows on the palms, soles, and flexor aspects of the
•LONGITUDINAL
FURROWS
RIDGES OF SKIN
INTERRUPTED BY
LONGITUDINAL
FURROWS
FURROWS
OF SKIN
FLEXION FURROWS
OPPOSITE THE
FLEXURE OF
THE JOINT
FIG. 792. — The furrows and ridges of the surface of the
skin from the palm or surface of the middle finger. (Toldt.)
THE SKIN
1189
digits are permanent, and over the palmar surface of the digits they are arranged
in definite forms which endure through life and are so distinctive that they have
been utilized by police officials in determining the identity of individuals. These
folds are due to the papillae of the skin being arranged in rows; some of the papillae
proliferate, and linear depressions occur in the horny layer (Philippson).
FIG. 793. — Anterior surface.
FIG. 794. — Posterior surface.
The general course of the connective-tissue bundles of the corium, determined by the direction assumed by the
linear clefts made in the skin when it is punctured by a round awl. (Langer.)
Fig. 792 shows skin ridges (cristae cutis), skin furrows (sidci cutls), furrows
opposite joints due to acts of flexron, and called flexure furrows, and longitudinal
furrows.
When the skin is punctured by a round awl it tends to split in a definite
direction, which direction varies with the region stabbed. These clefts are known
1190
THE ORGANS OF SPECIAL SENSE
as the lines of cleavage of Langer (Figs. 793 and 794), and depend upon the
arrangement of the connective-tissue bundles of the corium. These connective-
tissue bundles certainly influence the formation of folds and furrows. In many
portions of the body the cutaneous surface is divided by linear furrows into irregu-
larly shaped areas (Fig. 795). The skin consists of two layers: a superficial layer,
the epidermis, and a deep layer, the corium or dermis.
The Corium, Cutis Vera, Dermis or True Skin (Figs. 796, 797, and 799) is a
connective-tissue structure which arises from the mesoderm. It consists espe-
cially of connective tissue and elastic fibres; it contributes elasticity to the skin,
and is the seat of the sensitive layer. The corium is composed of two layers,
the reticular and the papillary.
MOUTH OF
HAIR-FOLLICLES'-
FIG. 795. — The furrows of the skin and the areas which these furrows delimit, reproduced from an impression of
the dorsal surface of the wrist. (Toldt.)
The Deep or Reticular Layer or Tunica Propria (stratum reticulare) rests upon
the subcutaneous tissue. It passes superficially into the papillary layer, and at
most places into the subcutaneous tissue without a sharp line of differentiation.
At some places, for instance in the nipple, the deep layer of the corium rests
upon a layer of muscular fibre. In the face this muscle-fibre is striated and sends
FURROWS OF SKIN
TOUCH CORPUSCLE
I STRATUM CORNEUS
EPIDERMIS^ STRATUM LUCIDUM
RETE MUCOSUM
( STRATUM PAPILLARE |
'STRATUM RE
TICULARE
ORIFICE OF
SUDORIFEROUS
DUCT
;\SUDORI FERGUS
'DUCT
CAPILLARY
~ LOOP OF
PAPILUE
BLOODVESSELS
OF CORIUM
BODY OF
--^SUDORIFEROUS
GLAND
FIG. 796. — Vertical section through the skin of the finger-tip. The layers of the epidermis and of the corium.
The subcutaneous areolar tissue. The sudoriferous or sweat-gland. (Toldt.)
prolongations to the papillary layer; in the nipple and scrotum it is non-striated.
The reticular layer is composed of bundles of white fibrous tissue, arranged in a
network. In the meshes of the network are fat, blood-vessels, lymphatics, seba-
ceous glands, sweat-glands, and hair-follicles.
The Subcutaneous Areolar Tissue or Tela Subcutanea (panniculus adiposus) con-
nects, the skin to the parts beneath; it is composed o£ bundles of connective tissue
THE 8KIN
1191
ARRCCTOR
PILI MUSCLE
EPIDERMIS
which cross repeatedly and form spaces. In almost all regions the spaces contain fat,
but in the scrotum and external ear they do not contain fat. When the connective-
tissue fibres of the panniculus adiposus are long and nearly parallel to the skin-
surface the skin becomes wrinkled; when they are short and nearly at right angles
to the surface, the skin cannot wrinkle.
The Superficial or Papillary Layer or Corpus Papillate of the Corium (stratum papil-
larc) lies just beneath the epidermis, contains the papillae, and is composed of a
network of fine bundles of fibrous tissue. The papillae are composed of fine
strands of connective tissue and elastic
tissue. They project from the corium
beneath the epidermis and enter into
depressions of the epidermis. They vary
greatly in size, averaging pg-^ of an inch
in height and 3-5-5- of an inch in width at
the base. In the face, especially in the
eyelids, they are insignificant. On the
glans penis, the palms of the hands, and
the soles of the feet, and in the nipples,
they are large. In the palmar surfaces
of the hands and fingers and the plantar
surfaces of the feet and toes they pro-
duce permanent ridges (Fig.798) . A ridge
is composed of two or more rows of
papillae, and the ducts of SWeat-glands
emerge between rows of papillae, and
open on the curved surface ridges (Fig.
798). Most of the papillae contain loops of capillaries, and are called vascular
papillae. Some contain nerve-terminations and are called nervous papillae. Be-
tween the papillary layer of the corium and the epidermis is a very thin and
structureless membrane called the basal membrane.
SUDORIFEROUS SUBCUTANEOUS
GLANDS AREOLAR TISSUE
FIG. 797. — Vertical section through the skin of the
PA PILL* OF
SUDORIFEROUS
DUCTS
FURROWS
OF SKIN
FIG. 798. — The furrows and ridges of true skin on the palmar surface of one of the fingers, the epidermis
having been removed. (Toldt.)
The Cuticle, Scarf Skin or Epidermis (Figs. 796, 797, 799, and 800).— The
cuticle, scarf skin or epidermis is composed of layers of epithelium and is
derived from the ectoderm. The epithelium is stratified, and there are no
blood-vessels. Two layers can be readily made out, the superficial or horny
layer and the deeper or Malpighian layer.
The Horny Layer (stratum corneum). — The horny layer is formed by several
layers of non-nucleated scaly cells. The cells consist of keratin. The surface
cells of the horny layers are being constantly rubbed off, and are being replaced
by cells from the Malpighian layer, which are converted into keratin as they near
the surface.
1192
THE ORGANS OF SPECIAL SENSE
The Malpighian Layer. — The Malpighian layer of the epidermis is divided into
four layers, named, from without inward, the stratum lucidum, the stratum granu-
losum, the stratum mucosum, and the stratum germinativum.
The Stratum Lucidum is not classified by all writers as part of the Malpighian
layer. Some anatomists classify it as a separate layer. It is here regarded as the
most superficial part of the Malpighian layer. It consists of several layers of flat
cells, the nuclei of which are beginning to disappear. The cells contain eleidin
granules. In regions where the epidermis is thin the stratum lucidum is absent.
The Stratum Granulosum consists of several layers of nucleated flat cells, con-
taining keratohyaline granules. These granules are probably formed from the
disintegrating nucleus, and in the stratum lucidum are converted into eleidin.
Superficial
layers
Rete
Mucosum
f Papilla
( Corium
i Epidermis
Cuticle
Derma
FIG. 799. — A sectional view of the skin (magnified).
The Mucous Layer, the Stratum Spinosum or the Stratum Mucosum consists of
numerous layers of nucleated, polygonal, spine-shaped cells known as prickle cells
or finger cells. Between the cells of the stratum mucosum are spaces containing
pigment granules and leukocytes. Processes from the prickle-cells join adjacent
cells. This layer contains numerous connective-tissue fibres arranged in a net-
work, and known as epidermic fibrils.
The Stratum Cylindricum or Stratum Germinativum is composed of cylindrical or
prickle-cells, the points of which are directed downward. Fine fibrils pass up
from the corium between the cells, and there is cement-substance as well between
them.
Pigmentation of the Skin. — As previously stated, in certain regions the skin of the
white race is brown because of pigmentation (areolae, nipples, around the anusr
axillae, scrotum, labia majora). This is due to pigment within the epithelial and
THE SKIN
1193
connective-tissue cells of the papillary layer of the corium, and in the basal cells
of the epidermis. There are few or none of these pigmented cells in the stratum
corneum of one of the Caucasian race.
Stratum corneum. <
Stratum lucidum.
Stratum granuJosum.
Stratum mueosum/
Malpighii. '
Stratum germinativum. j
-Nerve-fibrils.
FIG. 800. — Section of epidermis. (Ranvier.)
" In negroes and other colored races the deep pigmentation is due to a similar
distribution of the pigment granules in the entire epidermis; but even here the
pigmentation decreases toward the surface, although the uppermost cells of the
FIG. 801. — Microscopic section of skin, showing the epidermis and derma ; a hair in its follicle ;
the Erector pili muscle ; sebaceous and sudoriferous glands.
stratum corneum always contain some pigment. The nuclei of the cells are always
free from coloring matter. The question as to the origin of the pigment is as yet
unsolved."1
1 A Text-book of Histology. By A. A. Biihm and M. von Davidoff. Translated and edited by G. Carl Huber.
1194
THE ORGANS OF SPECIAL SENSE
The Arteries and Veins of the Skin (Fig. S02). — The arteries supplying the skin
vary in number, and vary much in size, being largest in regions exposed to
pressure, as the skin of the palms, soles, and buttocks. The arteries enter the
skin from a network in the subcutaneous tissue, and by an anastomosis in the
deepest part of the corium form a network (rete arteriosum cutaneum}. The vessels
send branches to the fat and to the sweat-glands. Branches from the network just
described ascend and form a second network in the corium beneath the papillae.
This is called the subpapillary network (rete arteriosum subpapillare). From this net-
work fine capillary vessels pass into the papillae, forming, in the smaller papillae,
a single capillary loop, but in the larger a more or less convoluted vessel. From
this network branches go to the hair-follicles and sebaceous glands. The blood
from the papillae passes into a plexus (rete venosum) beneath the papillae. This
RETE
VENOSUM
SUBPAPILLARY
NETWO
EPIDERMIS
— PAPILLARY LAYER-
RETE
VENOSUM
SUBCUTANEOUS
TISSUE
FIG. 802. — The distribution of the blood-vesseis in the skin of the sole of the foot. (Spalteholz.)
communicates with another plexus between the corium and subcutaneous tissue.
In some regions one or more retia are interposed between these two. The veins
from the sweat-glands, sebaceous glands, superficial fat, and hair-follicles are
received by the retia venosa. From the deepest rete veins pass to the subcuta-
neous tissue, and these veins enter the large subcutaneous veins.
The Lymphatics of the Skin. — There are numerous lymphatics supplied to the
skin which form two networks, superficial and deep, communicating with each
other and with the lymphatics of the subcutaneous tissue by oblique branches.
They originate in the cell-spaces of the tissue.
The Nerves of the Skin. — The nerves of the skin terminate partly in the epidermis
(Figs. 796 and 800) and partly in the cutis vera (Fig. 796). The former are pro-
longed into the epidermis from a dense plexus in the superficial layer of the corium
and terminate between the cells in bulbous extremities; or, according to some
observers, in the deep epithelial cells themselves. The latter terminate in end-bulbs,
touch-corpuscles, or Pacinian bodies (Figs. 524 and 796), in the manner already
described; and, in addition to these, a considerable number of fibrils are distrib-
uted to the hair-follicles, which are said to entwine about the follicle in a circular
THE NAILS
1195
manner. Other nerve-fibres are supplied to the plain muscular fibres of the hair-
follicles (arrectores pili) and to the muscular coat of the blood-vessels. These are
probably amyelinic fibres.
The Appendages of the Skin.
The appendages of the skin are the nails, the hairs, the sudoriferous and seba-
ceous glands, and their ducts.
The nails and hairs are peculiar modifications of the epidermis, consisting
essentially of the same cellular structure as that tissue.
Eponychium.
Nail.
Stratum
Stratum eo
of the nail
groove.
granulosum.
Corium.
Blood-vessel.
FIG. 803. — Longitudinal section through human nail and its nail groove (sulcus). (From Biihm and
Davidoff's Histology.
The Nails (ungues) (Figs. 803, 804, 805, 806, 807, and 808).— The nails are flat-
tened, elastic structures of a horny texture, placed upon the dorsal surface of the
terminal phalanges of the fingers and toes. Each nail is convex on its outer sur-
face, concave within. Its chief mass, called the body (corpus unguis), lies upon
the nail-bed. The free edge is called the margo liber. Each lateral margin (margo
lateralis), like the proxmial short edge of the nail (margo occultus), lies in a groove
of the cutis, the ungual fold (sulcus matricis unguis). The ungual wall (vallum
unguis) overlies the lateral and posterior edges. The nail is implanted by means
of a portion, called the root (radix unguis), into a groove in the skin. The root is
beneath the ungual wall and is composed of cells which have not yet become
Nail.
Stratum Malpighii;
Nail wail.
Nail groove.
Corium.
hod-vessel.
FIG. 804. — Transverse section through human nail and its sulcus. (From Bohm and Davidoff's Histology.)
horny. It is white in color. The nail has a very firm adhesion to the cutis vera,
being accurately moulded upon the surface of the true skin, as the epidermis is in
other parts. The part of the cutis beneath the body and root of the nail is called
the matrix (matrix unguis), because it is the part from which the nail is produced.
Corresponding to the body of the nail, the matrix is thick, and raised into a series
of longitudinal ridges (cristae matricis unguis}, which are very vascular, and the
color is seen through the transparent tissue. Behind this, near the root of the
nail, the papillae are small, less vascular, and have no regular arrangement, and
here the tissue of the nail is somewhat more opaque; hence this portion is of a
whiter color, and is called the lunula on account of its crescentic shape.
1196
THE ORGANS OF SPECIAL SENSE
The cuticle, as it passes forward on the dorsal surface of the finger or toe, is
attached to the surface of the nail, a little in advance of the nail root ; at the
extremity of the finger it is connected with the under surface of the nail a little
behind its free edge. The cuticle and the horny substance of the nail (both epi-
dermic structures) are thus directly continuous with each other. The nails con-
sist of a greatly thickened stratum lucidum, the stratum corneum forming merely
BODY
HORNY
"LAYER
RIDGES OF
MATRIX
NAIL-WALL
MALPIGHIAN
LAYER
SULCUS OF
MATRIX
LATERAL
MARGIN
RETINACULA
OF SKIN
RIDGES^;'
OF SKIN
PALMAR SURFACE
OF FINGER
FIG. 805. — Transverse section through the nail and the terminal portion of the ring finger. (Toldt.)
the thin cuticular fold (eponychium) which overlaps the lunula. The cells have
a laminated arrangement, and are essentially similar to those composing the
epidermis. The deepest layer of cells, which lie in contact with the papillae
of the matrix, are columnar in form and arranged perpendicularly to the surface;
those which succeed them are of a rounded or polygonal form, the more superficial
ones becoming broad, thin, and flattened, and so closely compacted as to make the
MATRIX OF NAIL
RIDGES OF
MATRIX
SULCUS OF
MATRIX
NAIL FOLD
CONCEALED MARGIN
FIG. 806. — The finger nail com-
pletely isolated, seen from the con-
vex side. (Toldt.)
NAIL WALL
FIG, 807.— The matrix of
the nail or nail-bed, with the
nail-fold and nail-walls dis-
played by the removal of the
epidermic portion of the nail
or nail proper and the sur-
rounding epidermis. (Toldt )
FIG. 808.— Matrix of the
nail with partly opened mar-
ginal groove of the nail-bed.
(Toldt.)
limits of each cell very indistinct. It is by the successive growth of new cells at
the root and under surface of the body of the nail that it advances forward and
maintains a due thickness, while, at the same time, the growth of the nail in the
proper direction is secured. As these cells in their turn become displaced by
the growth of new ones, they assume a flattened form, and finally become closely
compacted together into a firm, dense, horny texture. In chemical composition the
THE HAIRS
1197
FIBROUS
SUBSTANCE
nails resemble the upper layers of the epidermis, containing, however, a some-
what larger proportion of carbon and sulphur (Mulder).
The Hairs (pili) (Figs. 797, 799, 801, 809, 810, and 811).— The hairs are peculiar
modifications of the epidermis, and consist essentially of the same structure as
that membrane. They are found on nearly every part of the surface of the body,
excepting the palms of the hands, soles of the feet, the vermilion borders of the
lips, the dorsal surfaces of the phalanges, the nipples, the inner surface of the
prepuce, and the glans penis. Hairs include hairs of the head (capilla) ; of the eye-
brows (snpercilia) ; of the beard (barba) ; of the ears (tragi) ; of the nostrils (vibrissae) ;
the eyelashes (cilia) ; hairs of the axilla (hirci) ; pubes (pubes) ; and the small hairs
of the skin or woolly hairs (lanugo}.
They vary much in length, thick-
ness, and color in different parts of
the body and in different races of
mankind. In some parts, as in the
skin of the eyelids, they are so short
as not to project beyond the follicles
containing them; in others, as upon
the scalp, they are of considerable
length; again, in other parts, as the
eyelashes, the hairs of the pubic re-
gion, and the whiskers and beard,
they are remarkable for their thick-
ness. Straight hairs are stronger
than curly hairs, and present on
transverse section a cylindrical or ROOT
oval outline; curly hairs, on the
other hand, are flattened. The hairs
11 i i« OUTER
are usually oblique to the surface "BROUS LAYER
from which they arise (Fig. 797). INNER
Their direction depends upon the FIBROUS LAVER
region from which they spring, being
W^N^S'?' MEDULLARY
] SUBSTANCE
NECK OF
HAIR-FOLLICLE
INNER
ROOT-SHEATH
OUTER
ROOT-SHEATH
HYALINE
LAYER
FUNDUS OF
HAIR-FOLLICLE
SEBACEOUS
GLAND
ARRECTOR
PILI MUSCLE
HAIR-PAPILLA
FIG. 809. — A hair of the head still in the_ course of growth,
with hair-bulb in longitudinal section (Toldt.)
fairly regular in certain regions.
Thijs are formed hair-streams (flu-
mina pilorum) and hair-whirlpools
(vortices pilorum).
A hair consists of the root, the
part implanted in the skin ; the shaft
or stem, the portion projecting from
its surface; and the point.
The Root of the Hair (radix pili)
r»rp<5pnt« at itc *>Ytr*>rmtv a KulK/Mio
llty a DUlbOUS
enlargement, the hair-bulb (bulbus
pili) (Figs. 799 and 809), which is whiter in color and softer in texture than the shaft,
and is lodged in a follicular involution of the epidermis called the hair-follicle (follic-
ulus pili) (Figs. 797 and 801). When the hair is of considerable length the follicle
extends into the subcutaneous cellular tissue (Fig. 799). The hair-follicle com-
mences on the surface of the skin with a funnel-shaped opening, and passes inward
in an oblique or curved direction — the latter in curly hair — to become dilated at
its deep extremity or fundus (fundus folliculi pili), where it corresponds with the
bulbous condition of the hair which it contains. It has opening into it, near its
free extremity, the orifices of the ducts of one or more sebaceous glands (Figs.
799, 801, 809, and 810). At the bottom of each hair-follicle is a small conical,
vascular eminence or papilla, the hair-papilla (papilla pili} (Figs. 809 and 810),
1198
THE ORGANS OF SPECIAL SENSE
similar in every respect to the papillae found upon the surface of the skin; it is
continuous with the derraic layer of the follicle, is highly vascular, and is prob-
ably supplied with nerve fibrils. In structure the hair-follicle consists of two
coats — an outer or dermic, and an inner or epidermic (Figs. 809 and 811).
The Outer or Dermic Coat is formed mainly of fibrous tissue; it is continuous
with the corium, is highly vascular, and is supplied by numerous minute nerve
filaments. It consists of three layers. The most internal, the cuticular lining
of the follicle, consists of a hyaline basement-membrane, the hyaline layer, having
a glassy, transparent appearance, which is well marked in the larger hair-follicles,
but is not very distinct in the follicles of minute hairs. It is continuous with the
basement-membrane of the surface of the corium. External to this is the inner
fibrous layer, a compact layer of fibres and spindle-shaped cells arranged circularly
around the follicle. This layer extends from the bottom of the follicle as high as
the entrance of the ducts of the sebaceous glands. Externally is the outer fibrous
layer, a thick layer of connective tissue, arranged in longitudinal bundles, forming
a more open texture and corresponding to the reticular part of the corium. In this
are contained the blood-vessels and nerves.
EPIDERMIS.
CORIUM- -,
SUBCUTANEOUS
AREOLAR TISSUE
RETINACULA
OF SKIN
OCCIPITO-FRONTAL
APONEUROSIS
ARRECTOR
PILI MUSCLE
_SEBACEOUS
GLAND
SUDORIFEROUS
GLAND
— HAIR-FOLLICLE
-ROOT
HAIR-KNOB
-HAIR-BULB
FIG. 810. — Vertical section through the skin of the head. The hairs of the head in longitudinal section. (Toldt.)
The Inner or Epidermic Layer is closely adherent to the root of the hair, so that
when the hair is plucked from its follicle this layer most commonly adheres
to it and forms what is called the root-sheath. It consists of two strata, named
respectively the outer and inner root-sheaths ; the former of these corresponds with
the Malpighian layer of the epidermis, and resembles it in the rounded form and
soft character of its cells; at the bottom of the hair-follicle these cells become con-
tinuous with those of the root of the hair. The inner root-sheath consists of a
delicate cuticle next the hair, composed of a thin layer of imbricated scales having
a downward direction, so that they fit accurately over the upwardly directed
imbricated scales of the hair itself; then of one or two layers of horny, flattened
nucleated cells, known as Huxley's layer; and finally of a single layer of horny
oblong cells without visible nuclei, called Henle's layer.
The hair-follicle contains the root of the hair, which terminates in a bulbous
extremity, and is excavated so as to exactly fit the papilla from which it grows.
The bulb is composed of polyhedral epithelial cells, which as they pass upward
into the root of the hair become elongated and spindle-shaped, except some in the
centre which remain polyhedral. Some of these latter cells contain pigment-
THE HAIRS
1199
granules, which give rise to the color of the hair. It occasionally happens that
these pigment-granules completely fill the cells of the medullary substance in
the centre of the bulb, which gives rise to the dark tract of pigment often found,
of greater or less length, in the axis of the hair.
The Stem or Shaft of the Hair (scapus pili) (Fig. 809), consists of a central pith or
medulla, the fibrous part of the hair, and the true cuticle externally. The medulla
(substantia medullaris pili) occupies the centre of the shaft and ceases toward the
point of the hair. It is usually wanting in the fine hairs covering the surface of
the body, and commonly in those of the head. It is found in the shafts of all thick
hairs and in the deeper parts of the root of most hairs. It is more opaque and
deeper colored when viewed by transmitted light than the fibrous part; but when
viewed by reflected light it is white. It is composed of rows of polyhedral cells,
which contain granules of eleidin and frequently air-bubbles. The fibrous portion
or cortical substance of the hair (substantia corticalis pili) constitutes the chief part
of the shaft; its cells are elongated and unite to form flattened fusiform fibres.
Between the fibres ape found minute spaces which contain either pigment-granules
in dark hair or minute air-bubbles in white hair. In addition to this there is also a
CUTICLE OF
ROOT-SHEATH
OUTER .
FIBROUS
LAYER /<
HUXLEY'S
^ LAYER
\ OUTER
-•* ROOT- SHEATH
INNER
ROOT-SHEATH
MEDULLARY
SUBSTANCE
FIBROUS
SUBSTANCE
FIG. 811. — A moustache hair with its hair-follicle in transverse section. (Toldt.)
diffused pigment contained in the fibres. The cells which form the outer hair mem-
brane or true cuticle (cuticula pili) consist of a single layer which surrounds those of
the fibrous part; they are converted into thin, flat scales, having an imbricated
arrangement.
Connected with the hair-follicles are minute bundles of involuntary muscular
fibres, termed arrectores pili (mm. arrectores pilorum) (Figs. 797 and 809). They
arise from the superficial layer of the corium, and are inserted into the outer
surface of the hair-follicle, below the entrance of the duct of the sebaceous gland.
They are placed on the side toward which the hair slopes, and by their action
elevate the hair.1 When the hair is elevated a depression forms over the seat of
origin of the muscle, and the parts about the hair are elevated. This condition is
known as goose-skin. It is probable that the contraction of these muscles aids in
emptying sebaceous glands.
Blood-vessels and Nerves (Fig. 799). — A hair-follicle possesses a rich network of
capillaries about the hyaline membrane, and capillary loops pass to the papilla.
1 Arthur Thomson suggests that the contraction of these muscles on follicles which contain weak, flat hairs
will tend to produce a permanent curve in the follicle, and this curve will be impressed on the hair which is
moulded within it, so that the hair, on emerging through the skin, will be curled. Curved hair-follicles are
characteristic of the scalp of the Bushman. — ED. of 15th English edition.
1200 THE ORGANS OF SPECIAL SENSE
We have little knowledge as to nerve-terminations of the human hair. "In other
mammals the nerves end below the sebaceous glands. Myelinic fibres lose
their medullary sheaths, divide, and penetrate to the hyaline membrane. Here
some of the branches encircle the hair, while others end freely on the hyaline
membrane as naked axis-cylinders. These branch regularly and run parallel to
the long axis of the hair."1
The Sudoriferous or Sweat-glands (glandulae sudoriferae) (Figs. 796, 797, 799,
801, and 810). — The sudoriferous or sweat-glands are the organs by which a large
portion of the aqueous and gaseous materials is excreted by the skin. They are
found in almost every part of this structure, being absent on the red border of the
lips, the glans penis, and inner surface of the prepuce. On the eyelids they are some-
what modified, and are called ciliary glands (glandulae ciliares [Molli]) ; about the
anus they are extremely large, and are called circumanal glands (glandulae circum-
anales). The sweat-glands are situated in small pits below the under surface of the
corium, or, more frequently, in the subcutaneous areolar tissue, surrounded by a
quantity of adipose tissue. They are small, lobular, reddish bodies, consisting of
a single convoluted tube, from which the efferent duct (ductus sudoriferus) proceeds
upward through the corium and cuticle. The duct in the corium has true walls; in
the epidermis it has not individual walls, but is simply an epidermic tube. It
becomes somewhat dilated at its extremity, and opens on the surface of the cuticle by
an oblique valve-like aperture (porus sudoriferus). The duct, as it passes through
the epidermis, presents a spiral arrangement, being twisted like a corkscrew, in
those parts where the epidermis is thick; where, however, the epidermis is thin, the
spiral arrangement does not exist. In the superficial layers of the corium the duct
is straight, but in the deeper layers it is convoluted or even twisted. The spiral
course of these ducts is especially distinct in the thick cuticle of the palm of the
hand and sole of the foot. The size of the glands varies. They are especially
large in those regions where the flow of perspiration is copious, as in the
axillae, where they form a thin, mamillated layer of a reddish color, which
corresponds exactly to the situation of the hair in this region; they are large also in
the groin. Their number varies. They are most numerous on the palm of the hand,
presenting, according to Krause, 2800 orifices on a square inch of the integument,
and are rather less numerous on the sole of the foot. In both of these situations
the orifices of the ducts are exceedingly regular, and open on the curved surface
ridges. In other situations they are more irregularly scattered, but the number
in a given extent of surface presents a fairly uniform average. In the neck and
back they are least numerous, their number amounting to 417 on the square inch
(Krause). Their total number is estimated by the same writer at 2,381,248, and,
supposing the aperture of each gland to represent a surface of ^ of a line in
diameter, he calculates that the whole of these glands would present an evap-
orating surface of about eight square inches. Each gland consists of a single
tube intricately convoluted, terminating at one end by a blind extremity, and
opening at the other end upon the surface of the skin.
The wall of the tubercle of the secreting coil is lined with cubical epithelial
cells, external to these is a layer of smooth muscle-cells, and more externally a
layer of connective tissue, the membrana propria. The duct in the corium, in
contrast to the secreting coil, has no layer of muscle-cells, but instead a second
layer of epithelial cells covered by connective tissue. As previously stated, the
duct becomes spiral in the epidermis, its own wall disappears, and the channel
is bounded by epidermic cells.
Blood-vessels and Nerves. — The blood-vessels are branches from the subcuta-
neous vessels and the arterial plexus of the deep part of the corium. Numerous
1 Histology and Microscopic Anatomy. By Dr. Ladislaus Szymonowicz. Translated and edited by John
Bruce MacCallum, M.D.
THE SEBACEOUS GLANDS. 1201
ainyelinic nerve-fibres lie upon the merrfbrana propria of a sweat-gland. From
them fibrils pass inward and terminate by end-bulbs upon the cells of the gland.
The Sebaceous Glands (glandulaesebaceae). — The sebaceous glands are small,
sacculated, glandular organs, lodged in the substance of the corium. They are
found in most parts of the skin, and are usually connected with hair-follicles.
This connection is so common that they are sometimes called hair-follicle glands.
They are found in some regions which are devoid of hairs — the vermilion borders
of the lips, the labia minora, the glans penis, and prepuce. These glands are espe-
cially abundant in the scalp and face; they are also very numerous around the
apertures of the anus, nose, mouth, and external ear; but are wanting in the palms
of the hands and soles of the feet. Each gland consists of a single duct, more or
less capacious, which terminates in a cluster of small secreting pouches or saccules.
The sacculi connected with each duct vary, in number, as a rule, from two to five,
but in some instances may be as many as twenty. They are composed of a trans-
parent, colorless membrane, enclosing a number of epithelial cells. Those of
the outer or marginal layer are small and polyhedral, and are continuous with
the lining cells of the duct. The remainder of the sac is filled with larger cells,
containing fat, except in the centre, where the cells have become broken up, leav-
ing a cavity containing their de*bris and a mass of fatty matter, which constitutes
the sebaceous secretion. The orifices of the ducts open most frequently into the
hair-follicles, but occasionally upon the general surface, as in the labia minora and
the free margins of the lips. On the nose and face the glands are of large size,
distinctly lobulated, and often become much enlarged from the accumulation of
pent-up secretion. The largest sebaceous glands are those found in the eyelids —
the Meibomian glands.
76
THE OEGANS OF DIGESTION.
THE Apparatus for the Digestion of the Food (apparatus digestorius} consists
of the alimentary canal and of certain accessory organs.
THE ALIMENTARY CANAL.
The alimentary canal is a musculo-membranous tube, about thirty feet in
length, extending from the mouth to the anus, and lined throughout its entire
extent by mucous membrane. It has received different names in the various parts
of its course; at its commencement, the mouth, we find provision made for the
mechanical division of the food (mastication}, and for its admixture with a fluid
secreted by the salivary glands (insalivation) ; beyond this are the pharynx and
the oesophagus, the organs which convey the food (deglutition) into that part of
the alimentary canal, the stomach, in which the principal chemical changes occur,
and in which the reduction and solution of the food take place; in the small intes-
tines the nutritive principles of the food, the chyle, are separated, by its admixture
with the bile, pancreatic and intestinal fluids, from that portion which passes into
the large intestine, most of which is expelled from the system.
Alimentary Canal.
( Duodenum.
Mouth. Small intestine < Jejunum.
Pharynx. ( Ileum.
Oesophagus. f Caecum.
Stomach. Large intestine •< Colon.
( Rectum.
Accessory Organs.
Teeth.
( Parotid. Liver.
Salivary glands < Submaxillary. Pancreas.
( Sublingual. Spleen.
THE MOUTH, ORAL OR BUCCAL CAVITY (CAVUM ORIS).
The mouth is placed at the commencement of the alimentary canal; it is a
nearly oval-shaped cavity, in which the mastication and insalivation of the food
take place (Figs. 812, 831, and 837).
The aperture of the mouth (rima oris] is bounded by the lips. The angle of the
mouth (angulus oris) is formed on each side by the meeting of the upper and
lower lips (commissura labiorum). When at rest with the lips in contact, the rima
is a slightly curved line. Every movement which the lips make alters the shape
of the rima. When the mouth is closed the floor and roof are usually in contact
and its sides are approximated to the dental arches. The mouth consists of two
( 1203 )
1204
THE ORGANS OF DIGESTION
MOUTH
parts: an outer, smaller portion, the vestibule, and an inner, larger part, the cavity
proper of the mouth.
The Vestibule (vestibulum oris). — The vestibule is a slit-like space, bounded
in front and laterally by the lips and cheeks; behind and internally by the gums
and teeth. Above and below it is limited
by the reflection of the mucous membrane
from the lips and cheeks to the gum cover-
ing the upper and lower alveolar arch re-
spectively. It receives the secretion from the
parotid glands, and communicates, when the
jaws are closed, with the cavum oris by an
aperture on each side behind the wisdom
teeth.
The Cavity of the Mouth Proper (cavum
oris proprium). — The cavity of the mouth
proper is bounded laterally and in front
by the alveolar arches with their contained
teeth ; behind it communicates with the
pharynx by a constricted aperture termed
the isthmus faucium. It is roofed in by the
hard and soft palate. The greater part of the
floor is formed by the tongue, the remainder
being completed by the reflection of the mu-
cous membrane from the sides and under
surface of the tongue to the gum lining the
inner aspect of the mandible. It receives
the secretion from the submaxillary and
sublingual glands.
The Mucous Membrane. — The mucous
membrane lining the mouth is continuous
with the integument at the free margin of
the lips and with the mucous lining of the
pharynx behind ; it is of a rose-pink tinge
during life, and very thick where it covers the hard parts bounding the cavity.
It is covered by stratified epithelium.
SMALL
INTESTINE
ANUS
FIG. 812. — Diagram of the alimentary tube and
its appendages. (Testut.)
The Lips (Labia Oris).
The lips are two fleshy folds which surround the orifice of the mouth, formed
externally by integument and internally by mucous membrane, between which are
found the Orbicularis oris muscle (Fig. 263), the coronary vessels (Fig. 397), some
nerves (Fig. 397), areolar tissue, and fat, and numerous small labial glands.
The upper lip is called the labium superius; the lower lip is called the labium
inferius. The inner surface of each lip is connected in the middle line to the gum
of the corresponding jaw by a fold of mucous membrane, the frenulum (frenulum
labii superioris and frenulum labii inferioris). The frenulum labii superioris is
the larger of the two. On each side, external to the angle of the mouth, the lips
become continuous.
The Labial Glands (glandulae labiales) (Fig. 397)! — The labial glands are situated
between the mucous membrane and the Orbicularis oris muscle around the orifice
of the mouth. They are rounded in form, about the size of small peas, and their
ducts open by minute orifices upon the mucous membrane. In structure they
resemble the salivary glands.
•/•///•; TKKTH 1205
The Cheeks (Buccae)o
The cheeks form the sides of the face and are continuous in front with the lips.
They are composed externally of integument, internally of mucous membrane,
and between the two of a muscular stratum, besides a large quantity of fat, areolar
tissue, vessels, nerves, and buccal glands.
The Mucous Membrane. — The mucous membrane lining the cheek is reflected
above and below upon the gums, where its color becomes lighter; it is continuous
behind with the lining membrane of the soft palate. Opposite the second molar
tooth of the upper jaw is a papilla, the summit of which presents the aperture of
the duct of the parotid gland (ductus parotideus [Stenonis]) (Fig. 837). The prin-
cipal muscle of the cheek is the Buccinator, but numerous other muscles enter into
its formation — viz., the Zygomatici, Risorius Santorini, and Platysma myoides.
The Buccal Glands (glandulae buccales}. — The buccal glands are placed in the
submucous tissue between the mucous membrane and Buccinator muscle; they
are similar in structure to the labial glands, but smaller. Four or five glands of
larger size than the previously mentioned glands are placed beneath the mucous
membrane in the neighborhood of the last molar tooth. They are called the
molar glands (glandulae molares}. Their ducts open into the mouth opposite the
last molar tooth.
The Gums (Gingiva).
The gums are composed of a dense fibrous tissue closely connected to the
periosteum of the alveolar processes and surrounding the necks of the teeth. They
are covered by smooth and vascular mucous membrane, which is remarkable for
its limited sensibility. Around the necks of the teeth this membrane presents
numerous fine papillae; and from this point it is reflected into the alveolus, where
it is continuous with the periosteal membrane lining that cavity.
The Teeth (Dentes).
The human subject is provided with two sets of teeth, which make their appear-
ance at different periods of life. The first set appear in childhood, and are called
the temporary, deciduous or milk teeth. The second set are named permanent.
The temporary teeth are twenty in number — four incisors, two canine, and four
molars in each jaw (Figs. 813 and 830).
The permanent teeth are thirty-two in number — four incisors (two central and two
lateral), two canines, four bicuspids, and six molars in each jaw (Figs. 815 and 819).
General Characters (Fig. 820). — Each tooth consists of three portions; the
crown or body (corona dentis}, projecting above the gum; the root or fang (radix
dentis}, entirely concealed within the alveolus; and the neck (collum dentis}, the
constricted portion, between the root and crown.
Surfaces. — The surfaces of a tooth are named thus: that which comes in con-
tact with the teeth of the opposite jaw is the grinding or masticating surface (fades
masticatoria} ; that which touches the next tooth in the same row is the contact
surface (fades contactus). That surface which is toward its predecessor is called
the proximal surface (in incisors and canines, fades medialis; in molars and pre-
molars, fades anterior}. That surface which is toward its successor is called the
distal surface (in incisors and canines, fades lateralis; in molars and premolars,
fades posterior}. That which looks toward the lips and cheek is the labial or
buccal surface (fades labialis}. That toward the tongue is the lingual surface
(fades lingualis). In part this method of designation applies to the roots as well
as to the crowns of teeth.
1206
THE ORGANS OF DIGESTION
The Roots of the Teeth. — The roots of the teeth are firmly implanted within the
sockets or alveoli of the jaws (alveoli dentales) (see pp. 109 and 124). These depres-
sions are lined with periosteum, called the pericementum, which is reflected on to the
tooth at the point of the root and covers it as far as the neck. This is the root
membrane (periosteum alveolare). At the margin of the alveolus the periosteum
becomes continuous with the fibrous structure of the gums.
Right upper.
FIG. 813. — Deciduous teeth. Left aide.
FIG. 814. — Deciduous teeth. Lingual view.
Temporary, Deciduous or Milk Teeth (denies decidui)(Figs. 813, 814, and 830).
—The temporary or milk teeth are smaller, but resemble in form those of the per-
manent set. The neck is more marked, owing to the greater degree of convexity
of the labial and lingual surfaces of the crown. The hinder of the two temporary
molars is the largest of all the deciduous teeth, and is succeeded by the second
bicuspid. The first upper molar has only three cusps — two labial, one lingual; the
second upper molar has four cusps. The first lower molar has four cusps; the
second lower molar has five. The roots of the temporary molar teeth are smaller
and more diverging than those of the permanent set, but in other respects bear a
strong resemblance to them.
FIG. 815. — Permanent teeth, right side. (Burchard.)
Permanent Teeth (denies permanentes) (Figs. 815, 816, 817, and 819). The
Incisors (denies incisivi).—The incisors or cutting teeth are so named from their
presenting a sharp cutting edge, adapted for incising the food. They are eight in
number, and comprise the four front teeth in each jaw.
The crown is directed almost vertically and is spade-like in form ; it has the form
of a truncated cone whose top has been compressed into a sharp horizontal cutting
THE TEl'/ril
1207
edge. Before being subjected to attrition this edge presents three small elevations.
Titr labial surface is convex, and marked by free longitudinal ridges extending
from the edge tubercles toward the neck of the tooth. The lingual surface is con-
cave, and is marked by two marginal ridges extending from an encircling ridge
at the neck to the angles of the cutting edge of the tooth. The ridge at the neck
is termed the cingulum or basal ridge. The mesal and distal surfaces arc triangular,
the apex of the triangle being at the cutting edge. The neck of the tooth is
constricted. The root is long, single, and has the form of a transversely flattened
cone, thicker before than behind. The root may be curved.
The Incisors of the Upper Jaw are altogether larger and stronger than those of
the lower jaw, the central incisors being larger and flatter than the lateral incisors.
They are directed obliquely downward and forward.
The Incisors of the Lower Jaw are smaller and flatter than the upper, and the
elevations upon their lingual faces are not marked. The two central are smaller
than the two lateral incisors, being the smallest of all the teeth. The roots of these
teeth are flattened laterally.
FIG. 816. — Right half of upper jaw (from below),
with the corresponding teeth. The letters and numbers
point to the classes of teeth and the numbers in
classes.
FIG. 817. — Right half of lower jaw, with the cor-
responding teeth. The letter and numbers point to
the various cusps or their modifications on the dif-
ferent teeth. (Burchard.)
The Canine Teeth or Cuspidati (denies canini). — The canine teeth are four in
number, two in the upper, two in the lower jaw — one being placed distal to each
lateral incisor. They are larger and stronger than the incisors, especially in the
roots, which are deeply implanted and each causes a well-marked prominence
of the process at the place of insertion.
The crown is large, of spear-head form, and its very convex labial surface is
marked by three longitudinal ridges. The concave lingual surface is also marked
by three ridges which unite at a basal ridge. The point or cusp is longer than in
the other teeth, and is the point of division between a short mesal and a long
distal cutting edge. These two edges form an obtuse angle with each other.
The root is single, oval, or elliptical on transverse section, and is longer and more
prominent than the roots of the incisors.
The Upper Canines or cuspids, vulgarly called the eye teeth, are larger and longer
than the two lower, and in occlusion are distal to them to the extent of half the
width of the crown.
The Lower Canines, vulgarly called the stomach teeth, have the general form of
the upper cuspids, but their lingual surfaces are much more flattened, owing to
1208 THE ORGANS OF DIGESTION
the absence of the elevations marking the upper. Their roots are more flattened
and may be bifid at their apices.
The Bicuspid Teeth or the Premolars (denies premolares). — The bicuspid teeth
are eight in number, four in each jaw; they are placed distal to the cuspid teeth,
two upon each side of the jaw. They are double cuspids in form.
The crown is surmounted by two cusps, one buccal and one lingual, separated
by a groove, the buccal being more prominent and larger than the lingual. The
lower bicuspids are not truly bicuspid, the first having but a primitive lingual cusp,
the second having the lingual cusp divided into two sections — i. e., it is usually
tricuspid. The necks of the teeth are oval; the roots are single and laterally com-
pressed, that of the first upper bicuspid being frequently bifid. The first upper
bicuspid is usually the largest of the series. The roots of the lower bicuspids are
less compressed and more rounded.
The Molar Teeth, the Multicuspidati or Grinders (denies molar es}. — The molar
teeth are the largest and strongest teeth of the denture. They are adapted by
their forms for the crushing and grinding of the food. They are twelve in number,
six in each jaw, three being placed posterior to each second bicuspid.
The crowns are cuboidal in form, are convex buccally and lingually; they are
flattened mesally and distally. They are formed by the fusion of three primitive
cuspids in the upper and four in the lower. To these are added in the first and
second upper molars a disto-lingual tubercle, and in the first and third molars of
the lower jaw a disto-buccal tubercle. The unions of the primitive forms are
marked by sulci. The necks of these teeth are large and rhomboidal in form.
The roots of the upper molars are three in number — one large lingual or palatal
root, and two smaller buccal roots. In the lower molars, two roots are found, a
mesal and a distal, each of which is much flattened from before backward.
The First Molar Teeth are the largest of the dental series; they have four cusps
on the upper and five in the lower — three buccal and two lingual.
The Second Molars are smaller; the crowns of the upper are compressed until the
disto-lingual cusp is reduced. The crowns of the lower are almost rectangular,
with a cusp at each angle.
The Third Molars are called the wisdom teeth or dentes sapientae (denies serotini),
from their late eruption; they have three cusps upon the upper and five upon the
lower. The three roots of the upper are frequently fused together, forming a
grooved cone, which is usually curved backward. The roots of the lower, two
in number, are compressed together, and curve backward.
Arrangement of the Teeth.1 — The human teeth are arranged in two parabolic
arches, the upper row or arch (arcus dentalis superior} being larger, its teeth over-
lapping the lower row or arch (arcus dentalis inferior}. The average distance
between the centres of the condyles of the inferior maxillary bones is about four
inches, which is also the distance from either of these points to the line of junction
between the lower incisor teeth. Whether the jaw be large or small, the equilateral
triangle indicated is included in it; .the range of size is between three and one-half
and four and one-half inches.
Owing to the smaller sizes of the lower incisors, the teeth of the lower jaw are
each one-half a tooth in advance of its upper fellow, so that each tooth of the dental
series has two antagonists, with the exception of the lower central incisors and
upper third molars (Figs. 818 and 819).
The grinding faces of the upper bicuspids and molars curve progressively upward
and point outward, the first molar being at the lowest point of the curve, the third
molar at the highest. The curve of the lower dental arch is the reverse, the first
molar at its deepest part, the third molar at its extremity. The greater the depth
1 After Dr. W. G. A. Bonwill.
THE TEETH
1209
to which the upper incisors overlap the lower, the more marked this curve and
the more pointed are the cusps of the grinding teeth.
FIG. 818. — View of teeth in situ, with the external plates of the alveolar processes removed. (Cryer.)
FIG. 81ft. — Front and side views of the teeth and jaws. (Cryer.)
The movement of the human mandible is forward and downward, the resultant
of these directions being an oblique line, upon an average of 35 degrees from
the horizontal plane.1 When the lower jaw is advanced until the cutting edges of
W. E. Walker, Dental Cosmos, 1896.
1210
THE ORGANS OF DIGESTION
the incisors are in contact, the jaws are separated, but at the highest point of the
lower arch its third molar advances, and meets and rests upon a high point, the
second molar of the upper arch, and thus undue strain upon the incisors is obviated.
In the lateral movements of the mandible but one side is in effective action at
one time; the oblique positions of the cusps of the opposite teeth are such that
Pulp
cavity.
Root.
FIG. 820. — Vertical section of a molar tooth.
when either side is in action the other
is balanced at two or more points.
There is an anatomical correspond-
ence between the forms and arrange-
ment of the teeth, the form of the con-
dyle of the mandible, and the muscular
arrangement. Individuals who have
teeth with long cusps have the head of
the bone much rounded from before
backward, and have a preponderance
of the direct over the oblique muscles
of mastication, and vice versa; teeth
with short or no cusps are associated
with a flattened condyle and strong
oblique muscles.
Very great aberrations in the dental
arrangement are frequently followed by
accommodative changes in the heads of
the mandible.
Structure of the Teeth. The Dental
Pulp (pulpa dentis). — A longitudinal
section of a tooth will show the pres-
ence of a central chamber having the
general form of the crown of the tooth.
Processes of the chamber pass from its
body, one for each root and down each
root, and open at the apex by a minute
orifice. This cavity is known as the pulp-chamber or pulp-cavity (cavum dentis)
(Figs. 820 and 821). The minute canal in each root is called the pulp-canal or root-
canal (canalis radicis dentis). The foramen at the apex of the root is the apical
foramen (foramen apicis dentis). The cavity contains a soft, vascular, and sensitive
organ called the dental pulp (pulpa dentis). It is made up of fibrous cellular con-
nective tissue, the fibres of which are extremely fine, and contains numerous blood-
vessels and nerves, which enter by way of the apical foramina. It has not been
proved that there are lymphatics in the dental pulp, although some authors assert
that they exist (Wangermann and others). It seems to have been proved that the
spaces between the fibres of the pulp communicate with the lymphatic system. The
periphery of the pulp is bounded by a layer of cells arranged like columnar epithe-
lium, each cell sending one or more branched processes through the basic substance
FIG. 821. — Vertical section of a tooth in situ (15
diameters). C is placed in the pulp-cavity, opposite
the cervix or neck of the tooth ; the part above is tho
crown, that below is the root (fang). 1. Enamel with
radial and concentric markings. 2. Dentine with
tubules and incremental lines. 3. Cement or crusta
petrosa, with bone corpuscles. 4. Dental periosteum.
5. Bone of lower jaw.
777 /•; T MTU
1211
of the dentine. These processes constitute the dentine fibres. Other processes come
off from the cells which pass in the direction of the pulp and surround it. The
cells at the periphery of the pulp are the
dentine -forming cells, the odontoblasts of Wal-
deyer. The blood-vessels break up into in-
numerable capillary loops which lie beneath
the layer of odontoblasts. The nerve-fibrils
break up into numberless amyelinic fila-
ments, which spread out beneath the odonto-
blasts, and probably send terminal filaments
to the extreme periphery of the pulp outside
the odontoblasts.
The matrix cells and their processes are
irregularly arranged in the body of the pulp,
but in the canal portion the fibrillae are in the
direction of the axis of the root.
The Solid Portion of the Tooth.— The sec-
tion will exhibit three hard tissues in a tooth :
one, the proper dental substance, forming the
greater mass of the tooth; hence its name
dentine or ivory. The dentine upon the ex-
posed crown is sheathed by a layer called
the enamel ; the dentine of the root is en-
closed in a distinct tissue, the cementum or
crusta petrosa; both cementum and enamel are thinnest at the neck and thickest
upon their distal portions.
FIG. 822.- — From a ground-section through
the parts of a dentine, near the pulp, of a
human canine tooth which has been impreg-
nated with pigment. The dental canaliculi are
cut across and are joined together by side
branches. X 400.
Fir. 823. — Longitudinal ground-section through the apex of a canine tooth from a three-and-a-half-year-o/d
boy. The entrance of the dental canaliculi between the enamel prisms and the course taken by the latter are
Shown. X 135. (.Szymonowicz.)
1212
THE ORGANS OF DIGESTION
The Ivory or Dentine (substantiate eburnea) (Figs. 821,822, 823, and S24) forms
the principal mass of a tooth; in its central part is the cavity enclosing the pulp. It
is a modification of osseous tissue, from which it differs, however, in the fact that
it does not contain cells placed in cavities, but the cells lie in the periphery of the
pulp, against but not in the dentine. The dentine contains the processes of the
cells, which are known as dental or dentinal fibres. On microscopic examination
it is seen to consist of a number of minute wavy and branching tubes having
distinct parietes. They are called the dentinal tubuli or dental canals, and are
embedded in a dense homogeneous substance, the intertubular tissue.
The dentinal tubuli (canaliculi dentales) (Fig. 824) are placed parallel with one
another, and open at their inner ends into the pulp-cavity. In their course to the
periphery they present two or three curves, and are twisted on themselves in a spiral
direction. The direction of these tubes varies; they are vertical in the upper por-
tion of the crown, oblique in the
neck and Upper part of the root,
and toward the lower part of the
root they are inclined downward.
The tubuli, at their commence-
ment, are about 4-5*5-5- of an inch in
diameter; in their course they di-
vide and subdivide dichotomously,
so as to give to the cut surface of
the dentine a striated appearance.
From the sides of the tubes, espe-
cially in the root, ramifications of
extreme minuteness are given off,
which join together in loops in the
intertubular substance, or termin-
ate in small dilatations, from which
branches are given off. Near the
pulp the lateral branches are few
and are almost at right angles to
the canals. Nearer the periphery
the lateral branches are more nu-
merous, and they come off at
acute angles. The terminations of
the chief canals at the periphery
vary. In the crown they break up
into branches like fingers just be-
neath the enamel. Some of these
finger-like branches leave the den-
tine and enter the cement substance between enamel prisms. The majority of
the chief canals end in blind extremities at the margin of the enamel and do not
enter this structure. In the lower portion of the tooth the chief canals do not
emerge from the dentine, but end at the margin of the cement in blind extremities.
They may reach the spaces of the granular sheath. Near the periphery of the
dentine of the crown the finer ramifications of the tubuli pass through a layer of
irregular branched spaces which communicate with each other. These are called
the interglobular spaces of Czermak (spatia inter globular ia) (Fig. 824, J). These
spaces are gaps in the dentine due to failure of calcification and are filled with
uncalcified dentine. The outer part of the dentine in the lower portion of the
tooth contains a layer of interglobular spaces known as the granular layer or
granular sheath of Tomes. The dentinal tubuli have comparatively thick walls,
and contain slender cylindrical prolongations from the processes of the cells of
\'. \ '• \ . : ' ' :
FIG. 824. — Ground-section through the root of a human
premolar. D, dentine ; K, cement corpusctes ; O, osteoblasts ;
Ep., remains of Hertwig's epithelial sheath, 200 diameters ;
/, interglobular spaces. (Rose.)
THE TEETH
1213
the pulp-tissue already mentioned, and first described by Mr. Tomes and named
Tomes's fibres or dentinal fibres. These dentinal fibres are analogous to the soft
contents of the canaliculi of bone. Between Tomes's fibres and the ivory around
the canals there is a tissue which is markedly resistant to the action of acids — the
dentinal sheath of Neumann.
The intertubular substance or tissue is translucent and contains the chief part
of the earthy matter of the dentine. After the earthy matter has been removed
by steeping a tooth in weak acid the animal basis remaining may be torn into
laminae which run parallel with the pulp-cavity across the direction of the tubules.
These laminae show the method of growth to be by deposition of successive strata
of dentine. Fibrils have been found in the matrix of the intertubular substance,
and are probably continuous with the dentinal fibres of Tomes. In a dry tooth a
section of dentine often displays a series of lines — the incremental lines of Salter —
which are parallel with the laminae above mentioned. These lines are caused by
two facts: (1) The imperfect calcification of the dentinal laminae immediately
adjacent to the line. (2) The drying process, which reveals these defects in the
calcification. These lines are wide or narrow according. to the number of laminae
involved, and along their course, in consequence of the imperfection in the calci-
fying process, little irregular cavities are left, which are the interglobular spaces
already referred to. They have received their name from the fact that they are
surrounded by minute nodules or globules of dentine. Other curved lines may
be seen parallel to the surface. These are the concentric lines of Schreger, and are
due to the optical effect of simultaneous curvature of the dentinal tubules.
A
FIG. 825. — Enamel prisms (350 diameters). A, fragments and single fibres of the enamel isolated by the action
of hydrochloric acid. B, surface of a small fragment of enamel, showing the hexagonal ends of the fibres.
CHEMICAL COMPOSITION. — According to Berzelius and Bibra, dentine consists
of twenty-eight parts of animal and seventy-two of earthy matter. The animal
matter is resolvable by boiling into gelatin. The earthy matter consists of phos-
phate and carbonate of calcium, with a trace of fluoride of calcium, phosphate of
magnesia, and other salts.
The Enamel (substantia adamantina) (Figs. 821, 823, and 825) is the hardest and
most compact part of a tooth, and forms a thin crust over the exposed part of
the crown as far as the commencement of the root. It is thickest on the grind-
ing surface of the crown until worn away by attrition, and becomes thinner toward
the neck. It consists of a congeries of minute hexagonal rods, columns, or prisms
known as enamel fibres or enamel prisms (prismata adamantina} (Fig. 825). In
general, they lie parallel with one another, resting by one extremity upon the
dentine, which presents a number of minute depressions for their reception, and
1214 THE ORGANS OF DIGESTION
forming the free surface of the crown by the other extremity. There are occa-
sional collections of prisms which run diagonally. The prisms are directed
vertically on the summit of the crown, horizontally at the sides; they are about
the s-gVo" of an inch in diameter, and pursue a more or less wavy course. By
reflected light radial striations are visible. These are Schreger's lines, and are
due to the fact that the prisms take an undulatory course and those of two layers
may have opposite directions. Another series of lines, having a brown appear-
ance from pigmentation, and denominated the parallel striae or brown striae of
Retzius or the colored lines, are seen on a section of the enamel. These lines
are concentric and cross the enamel rods. They are caused by the mode of
enamel deposition. Inasmuch as the enamel columns, when near the dentine,
cross each other and only become parallel farther away, a series of radial mark-
ings, light and dark alternately, is obtained (Fig. 821). The enamel prisms are
themselves calcified and are fixed to each other by a very small amount of cement
substance. Numerous minute interstices intervene between the enamel-fibres
near their dentinal surface. It is noted that some of the dentinal canals at the
crown penetrate a certain distance between the rods of the enamel (Fig. 823). No
nutritive canals exist in the enamel, except the very few dentinal canals which at
the crown penetrate a short distance, and these are found only in a small area.
CHEMICAL COMPOSITION. — According to Bibra, enamel consists of 96.5 per cent,
of earthy matter and 3.5 per cent, of animal matter. The earthy matter consists
of the phosphate and the carbonate of calcium, with traces of fluoride of calcium,
phosphate of magnesia, and other salts.
The enamel of a recently erupted tooth is covered by a membrane, the thick-
ness of which is joTo" °f an mcn- It is known as enamel cuticle or Nasmyth's mem-
brane (cuticula dentis). It is probably the most recent, and hence an uncalcified,
or partly calcified enamel layer. Some believe it to be a product of the outer layer
of the cells of the enamel organ.
The Cortical Substance, Cementum or Crusta Petrosa (substantia ossea) (Figs. 808
and 81 1) is disposed as a thin layer on the roots and neck of a tooth, from the termi-
nation of the enamel as far as the apex of the root, where it is usually very thick. At
the neck it overlays a slight margin of enamel. In structure and chemical com-
position it is true bone. It contains, sparingly, the lacunae and canaliculi which
characterize true bone; the lacunae placed near the surface have the canaliculi radi-
ating from the side of the lacunae toward the periodontal membrane or dental
periosteum, and those more deeply placed join with adjacent dentinal tubuli. The
teeth of the young usually contain Haversian systems in the thicker portions of
the cementum. The neck of the tooth does not contain lacunae. The cementum
is occasionally laminated. Sharpey's fibres (p. 37) are very numerous. Some of
the lacunae of the cementum receive dentinal tubes from the dentine.
As age advances the cement increases in thickness, and gives rise to those bony growths, or
exostoses, so common in the teeth of the aged; the pulp-cavity becomes also partially filled up
by a hard substance intermediate in structure between dentine and bone (the osteo-dentine of
Owen; the secondary dentine of Tomes). It is formed by the odontoblasts, the dental pulp
lessening in volume.
Development of the Teeth (Figs. 826, 827, 828, and 829).— The teeth are an
evolution from the dermoid system, and not of the bony skeleton; they are devel-
oped from two of the blastodermic layers, the epiblast and mesoblast. From the
former the enamel is developed; from the latter the dentinal pulp, dentine, cemen-
tum, and pericementum. It is customary to view the development of the per-
manent and temporary teeth as separate studies.
The earliest evidence of tooth-formation in the human embryo is observed
about the seventh week. The mucous membrane covering the embryonic jaws is
seen to rise as a longitudinal ridge along the summit of each jaw. This ridge is
THE TEETH
121.')
the maxillary rampart of Kblliker and Waldeyer. A transverse section through the
jaw will show the elevation to be due to a linear and outlined activity of the
germinal epithelial layer; a corresponding epithelial growth is seen to sink as a
band into the mesoblastic tissue beneath. This band is called the dental lamina
or dental band. The local cell-activity continues, and in its descent the band
appears to meet with a resistance which 'causes a flattening of its extremity into a
continuous lamina. From the inner (toward the tongue) edge of the lamina
epithelial cords are given off, ten in number, one for each temporary tooth.
FIG. 826. — Diagram of method of development of the teeth. 1. Early stage. 4. Later stage. 2, 3. Inter-
mediate stages, s. Common dental germ. o. Special dental germ (milk), o'. Special dental germ (permanent).
p. Papilla, e. Dental furrow. (Gegenbauer.)
The growth of each cord continues, and each expands into a flask-like form, the
walls covered by a layer of germinal cells, its interior by swollen mature cells.
The ingrowing bulb is now seen to flatten upon its lower surface, as though it had
met with an outlined resistance from the mesoblastic tissue beneath. The epithelial
ingrowth assumes the general form of the several teeth; it is the enamel-organ of
the tooth (Fig. 826). The cellular tissue of the jaw beneath the cap of the enamel-
organ grows and projects into the cap. This projection is the dentine papilla
(papilla dentis). At this period the mesoblastic tissue around each enamel-organ
is seen to become differentiated into fibrous tissue surrounding the enamel-organs,
Dental furrow
Remains of ' ' neck" of
enamel organ, or of the —
common dental germ
Permanent special
dental germ
Meckel's cartilage.
Dental sac
Enamel pulp
External enamel
layer
Papilla
Lover jaw.
FIG. 827. — Vertical section of the inferior maxilla of an early human foetus. (Magnified 25 diameters.)
but at some distance from them. Islets of bone are also seen to be forming the
beginning of the bony maxillae.
The indentation of the base of the enamel-organ continues until it assumes
the form of the future teeth. The cells bounding the organ assumes a cylindrical
form; the cells of the interior become much expanded, and irregular in size and
form.
The mesoblastic tissue underlying the enamel-organ is much condensed; evi-
dences of cellular differentiation and a vascular system appear. Bone continues to
1216
THE ORGANS OF DIGESTION
develop until all of the tooth-follicles are embraced in a gutter of bone. From the
lingual side of the cords of the temporary teeth epithelial buds are given off, which
sink into the mesoblastic tissue and form the enamel-organs of the permanent
teeth. The condensation of fibrous tissue continues until each embryonic tooth is
enveloped in a sac, the dental sac (Fig. 827) ; this, together with all of its contents,
is called the dental follicle.
The tooth which is undergoing development with its enamel-organ and dentine
papilla is known as the tooth germ. This tooth germ is encompassed and shut off
from surrounding structures by the bag of membranous structure known as the
dental sac.
The cells of the enamel-organ now undergo a series of differentiations: the
inner layer, arranged as columnar epithelium, are the enamel cells, or ameloblasts.
The layer is called the ameloblastic or enamel-forming layer (Figs. 827 and 828).
The cells of the outer wall remain cuboidal ; the cells which lie between become
much distended, and on account of their appearance when seen in section this
portion of the organ is called the enamel jelly or the stellate reticulum. The layer of
cells immediately contiguous to the ameloblasts form a layer called the stratum
intermedium (Fig. 828 A, D).
Dentine.
Enamel.
FIG. 828. — A. Section through tooth-follicle — human canine seven and one-half months. A. Follicular wall.
B. Outer epithelial coat. V. Stellate reticulum. D. Stratum intermedium. E. Ameloblasts. F. Odonto-
blasts. O. Pulp.
B. Diagram after Williams (Dental Cosmos, 1896), mode of enamel deposition. A. Blood-supply to B, secret-
ing papillae. C. Layer of ameloblasts containing enamel globules and droplets of calcoglobulin. D. Enamel-
globules deposited. E. Formed dentine. F. Forming dentine. 6. Layer of odontoblasts. H. Blood-supply
to odontoblastic layer.
The enclosed mesoblastic papilla (the future dental pulp) has its peripheral cells,
which are called odontoblasts, differentiated into columnar bodies disposed as a
layer, each cell having a large nucleus. The vascular supply of the pulp is now
well marked. A section of a follicle at this period will exhibit the follicular wall
springing from the base of the dental papilla and having a well-marked blood-
supply. The bony alveolar walls are well outlined, and evidences of a periosteum
appear (Figs. 827 and 828).
Development of Enamel (Fig. 828 B). — In point of time, the deposition of den-
tine actually begins before that of enamel, so that the first-formed layer of enamel
is deposited against a layer of immature dentine. The enamel is built up of two
distinct substances — globules of uniform size which are formed by the amelo-
blasts, and a cementing substance, probably an albuminate of calcium (calco-
globulin), the basis of all the calcified tissues. At the ends of the ameloblasts,
THE TEETH 1217
next to the dentine, the secretion of calco-globulin is deposited, and into the
plastic mass the enamel-globules are extruded, each globule remaining con-
nected with the ameloblasts by plasmic strings, which also join the globules
laterally.1
The first deposit of enamel begins in the tips of the cusps, and is quickly fol-
lowed by a disappearance of the stellate reticulum at that point; the stellate retic-
ulum appears to atrophy, so that the vascular follicular wall is brought into
direct apposition with the stratum intermedium, which becomes differentiated into
a glandular (secreting) tissue which elaborates the calcic albuminous basis of the
enamel. The secretion passes from the cells of the stratum intermedium through a
membrane into the ameloblasts, where it is in part combined with the cellular
globules, and irregular masses of it are extruded as cementing substance. The
deposition continues until the enamel-cap has its typical form. The deposition
of the layers of globules is indicated by parallel lines transverse to the axes of the
enamel-rods. At the completion of amelification the ameloblasts are partially
calcified and form the enamel cuticle or Nasmyth's membrane (cuticula dentis).
Formation of Dentine. — The layer of columnar cells bounding the periphery of
the pulp, the odontoblasts, are in apposition with a plexus of capillary vessels
(Fig. 829). Each cell is a secreting body which selects the material for dentine-
building. Against the layer of ameloblasts
covering the dental papilla the odontoblasts
deposit globules, of the calcium albuminate,
and receding as the deposits are made, leave
one or more protoplasmic processes in the
calcic deposit. These are known as Tomes 's
fibres. The process continues until the normal
dentine thickness is formed. The deposit is ±1
laid down in a scaffolding of finely fibrillated
tissue. The layer of formative cells remains Flo 829._Part of section
constant. The remains of the dentine papilla tooth of young rat, showing the mode of
. i • deposition of the dentine (highly magnified).
Constitute the pulp and lie in the pulp-Cavity «• Outer layer of fully-calcified dentine.
1O1A\ ' Uncalcined matrix with a few nodules of
(p. I^IU). calcareous matter. c. Odontoblasts with
•n .. , „ TT • processes extending into the dentine, d. Pulp.
Formation Of CementUm. HertWlg asserts foe section is stained with carmine, which
that the epithelial edge of the enamel organ cYfiedSparetuncal
formed by the inner and outer epithelial layers
of the organ grows downward, or rather the developing tooth grows upward until
the future root-form of the tooth is outlined by a double layer of epithelial cells,
constituting the root-sheath of Hertwig. The growth of the alveolar process is
synchronous.
Upon the pulp side of the sheath a layer of odontoblasts is developed; upon
the outer side the fibrous encasement becomes closely attached to the sheath and a
layer of osteogenetic cells is differentiated. These cells are called cementoblasts.
The growth of the dentine of the root is exactly similar to the growth of that of
the crown. The epithelial sheath undergoes atrophic changes, leaving the epithe-
lial whorls which remain in the pericementum. The cementum is developed as
subperiosteal bone. The cementum over the apex of the root is not formed until
after the eruption of the tooth.
Formation of Alveoli. — By the time the crowns of the teeth have formed, each
is enclosed in a loculus of bone which has developed around it and at some distance
from it; the loculus is open at the top toward the gums, where it is closed by
fibrous tissue; the developing permanent tooth is contained in the same loculus,
but is later separated from the temporary tooth by a growth of bone. The alveolar
1 J. L. Williams, Dental Cosmos, 1896.
77
1218 THE ORGANS OF DIGESTION
process is not completed until after the eruption of the teeth. During eruption
that portion of the process overlying the crown undergoes absorption, and as soon
as the immature tooth has erupted the alveolar process is developed about the root,
whose formation is also completed after eruption.
Development of the Permanent Teeth. — The permanent teeth as regards their
development may be divided into two sets: (1) those which replace the temporary
teeth, and which, like them, are ten in number; these are the successional perma-
nent teeth; and (2) those which have no temporary predecessors, but are super-
added at the back of the dental series. These are three in number on either side
in each jaw, and are termed the superadded permanent teeth. They are the three
molars of the permanent set, the molars of the temporary set being replaced by
the premolars or bicuspids of the permanent set.
The Development of the Successional Permanent Teeth — the ten anterior ones
in either jaw — will be first considered. As already stated, the germ of each
milk tooth is a special thickening of the "free" edge of the common dental germ
or dental lamina. In like manner is formed the special dental germ of each of
the successional permanent teeth. But these thickenings are not at the "free"
edge of the dental lamina, but occur behind and lateral to each of the milk-tooth
germs (Fig. 826). There are ten of these, and they appear in order, about the
sixteenth week, on each side, the central incisor germs being the first.
These special dental germs now go through the same transformations as
were described in connection with those of the milk teeth, and the changes also
eventuate in the germs becoming enamel organs; that is, they recede into the
substance of the gum behind the germs of the temporary teeth. As they recede
they become flask-shaped, form an expansion of their distal extremity, and finally
meet a papilla, which has been formed in the mesoblast, just in the same
manner as was the case in the temporary teeth. The apex of the papilla inden-
tates the dental germ, which encloses it, and forming a cap for it, undergoes
analogous changes to those described in the development of the milk teeth, and
becomes converted into the enamel, whilst the papilla forms the dentine of the
permanent tooth. In its development it becomes enclosed in a dentinal sac which
adheres to the back of the sac of the temporary tooth. The sac of each perma-
nent tooth is also connected with the fibrous tissue of the gum by a slender band
of the gubernaculum, which passes to the margin of the jaw behind the correspond-
ing milk tooth (see above).
The Superadded Permanent Teeth — three on each side in each jaw— arise from
successive extensions backward — i. e., along the line of the jaw — of the common
dental germ from the back part of the special dental germ of the immediately
preceding tooth. During the fourth month or seventeenth week, in that portion
of the common dental germ which lies behind — i. e., lateral to the special dental
germ of the last temporary molar tooth, and which has hitherto remained unal-
tered— there is developed the special dental germ of the first permanent molar
into which a papilla projects. In a similar manner, about the fourth month after
birth the second molar is formed, and about the third year the third molar.
Eruption. — When the calcification of the different tissues of the milk tooth
is sufficiently advanced to enable it to bear the pressure to which it will be after-
ward subjected, its eruption takes place, the tooth making its way through the
gum. The gum is absorbed by the pressure of the crown of the tooth against it,
which is itself pressed up by the increasing size of the fang. At the same time
the septa between the dentinal sacs, at first fibrous in structure, ossify and thus
form the loculi or alveoli ; these firmly embrace the necks of the teeth and afford
them a solid basis.
Previous to the permanent teeth penetrating the gum, the bony partitions
which separate their sacs from the deciduous teeth are absorbed, the roots of
THE TEETH
1219
the temporary teeth disappear by absorption through the agency of particular
multinucleated cells, called odontoclasts, which are developed at the time in the
neighborhood of the root, and the permanent teeth become placed under the
loose crown of the deciduous teeth; the latter finally become detached, and the
permanent teeth take their place in the mouth (Fig. 830).
FIG. 830. — The milk-teeth in a child of about four years. The permanent teeth are seen in their alveoli. (Cryer.)
Calcification of the permanent teeth proceeds in the following order: First
molar, soon after birth; the central incisor, lateral incisor, and cuspid, about six
months afte~r birth; the bicuspids, at the second year or later; second molar, end
of second year; third molar, about the twelfth year.
The Eruption of the Temporary Teeth commences at the seventh month, and is
complete about the end of the second year.
The periods for the eruption of the temporary set are (C. S. Tomes)—
Lower central incisors
Upper incisors ....
Lower lateral incisors and first molars
Canines ......
Second molars «
6 to 9 months.
8 to 10 "
15 to 21 "
16 to 20 "
20 to 24 "
The Eruption of the Permanent Teeth takes place at the following periods, the
teeth of the lower jaw preceding those of the upper by a short interval :
6J years, first molars.
7th year, two middle incisors.
8th year, two lateral incisors.
9th year, first bicuspid.
10th year, second biscuspid.
llth to 12th year, canine,
J2th to 13th year, second molars.
17th to 21st year, third molars,
1220
THE ORGANS OF DIGESTION
The Palate (Palatum).
The palate forms the roof of the mouth; it consists of two portions, the hard
palate in front, the soft palate behind.
The Hard Palate (palatum durum) (Figs. 831 and 832). — The hard palate is
bounded in front and at the sides by the upper alveolar arches and gums. In
front and to the sides it is continuous with the gums; behind, it is continuous
with the soft palate. It is formed by the palate processes of the superior maxil-
lary bones and the palate processes of the palate bones (Fig. 72) . It is covered by a
dense structure formed by the periosteum and mucous membrane of the mouth,
which are intimately adherent, particularly to the front and sides, by means of
ANTERIOR
PILLAR
POSTERIOR
PILLAR
FIG. 831. — Antero-inferior surface of the soft palate. The tongue has been removed, so that the pharyngeal
isthmus is distinctly seen. (Luschka.)
a layer of fibrous tissue. Along the middle line is a linear ridge or raphe (raphe
palati), which terminates anteriorly in a small papilla, the incisive papilla (papilla
incisiva), corresponding with the inferior opening of the anterior palatine fossa.
This papilla receives filaments from the naso-palatine and anterior palatine
nerves. The incisive papilla in a recently born child is continuous with the
gum and the frenulum of the upper lip. On either side and in front of the raphe
the mucous membrane is thick, pale in color, and corrugated; these corruga-
tions, which are composed of fibrous tissue, are the palatine rugae (plicae pala-
tinae transversae). In very young children the rugae are distinct and definite.
In the aged they are indistinct. Behind, it is thin, smooth, and of a deeper
color; it is covered with squamous epithelium, and the fibrous tissue beneath it
THE PALATE
1221
contains many mucous glands, the palatine glands (glandulae palatinae). The
palatine vessels and nerves lie in the fibrous tissue beneath the mucous membrane.
The Soft Palate or Velum Pendulum Palati (palatum molle) (Figs. 831, 832,
and 837). — The soft palate is a movable fold suspended from the posterior border
of the hard palate, and forming an incomplete septum between the mouth and
pharynx. It consists of a fold of mucous membrane enclosing muscular fibres,
an aponeurosis, vessels, nerves, adenoid tissue, and mucous glands. When
occupying its usual position it is relaxed and pendent and its oral surface is
concave, continuous with the roof of the mouth, and marked by a median ridge
or raphe, which indicates its original separation into two lateral halves. Its
pharyngeal surface is convex, and continuous with the mucous membrane cover-
ANTERIOR
PALATINE CANAL
DESCENDING
PALATINE
ARTERY
FIG. 832. — The palatine vault on the right side of the mucous membrane has been removed. The left side shows
the mucous membrane and the glandular layer. (Poirier and Charpy )
ing the floor of the posterior nares. Its anterior or upper border is attached to
the posterior margin of the hard palate, and its sides are blended with the
pharynx. Its posterior or lower border is free. The posterior portion of the
soft palate is known as the vail of the palate (velum palatinum} and terminates
posteriorly and externally on each side in a free margin, the posterior arch of
the palate.
Hanging from the middle of its lower border is a small, conical-shaped, pen-
dulous process, the uvula (uvula palatina). The uvula varies greatly in length ia
different individuals. It is composed of glands and connective tissue, contains a
prolongation of the Azjgos uvulae muscle and is covered with mucous membrane,
and arching outward and' down ward from the base of the uvula on each side are
two curved folds of mucous membrane, containing muscular fibres, called the
arches or pillars of the soft palate or pillars of the fauces (arcus palatini).
1222 THE ORGANS OF DIGESTION
The Anterior Pillar (arcus glossopalatinus) (Figs. 831 and 837).— The anterior
pillar on each side runs downward, outward, and forward to the side of the base
of the 'tongue. These pillars are formed by the projection of the Palato-glossi
muscles, covered by mucous membrane.
The Posterior Pillar (arcus pharyngopalatinus) (Figs. 831 and 837). — The pos-
terior pillar on each side is nearer to its opposite arch than is the anterior pillar to its
opposite. These pillars are larger than the anterior; they run downward, outward,
and backward to the sides of the pharynx, and are formed by the projection of the
Palato-pharyngei muscles, covered by mucous membrane. The anterior and pos-
terior pillars are separated below by a triangular interval in which the tonsil is lodged.
The space left between the arches of the palate on the two sides is called the
isthmus of the fauces (isthmus faucium). It is bounded, above, by the free margin
of the soft palate; below, by the back of the tongue; and on each side by the
pillars of the fauces and the tonsils. Through this isthmus the mouth com-
municates with the pharynx.
The Mucous Membrane of the Soft Palate. — The mucous membrane of the soft
palate is thin, and covered with squamous epithelium on both surfaces, excepting
near the orifice of the Eustachian tube, where its epithelium is columnar and
ciliated.1 Beneath the mucous membrane on the oral surface of the soft palate
is a considerable amount of adenoid tissue. The palatine glands form a con-
tinuous layer on the pharyngeal surface and around the uvula.
The Aponeurosis of the Soft Palate. — The aponeurosis of the soft palate is a thin
but firm fibrous layer attached above to the posterior border of the hard palate,
and becoming thinner toward the free margin of the velum. Laterally, it is con-
tinuous with the pharyngeal aponeurosis. It forms the framework of the soft
palate, and is joined by the tendons of the Tensor palati muscles.
The Muscles of the Soft Palate. — The muscles of the soft palate are six on each
side: the Levator palati, Tensor palati, Azygos uvulae, Palato-glossus, Palato-
pharyngeus and Salpingo-pharyngeus (see p. 407). The following is the relative
position of these structures in a dissection of the soft palate from the posterior or
naso-pharyngeal to the anterior or oral surface : Immediately beneath the pharyn-
geal mucous membrane is a thin stratum of muscular fibres, the posterior fasciculus
of the Palato-pharyngeus muscle, joining with its fellow of the opposite side in the
middle line. This posterior fasciculus is joined by the Salpingo-pharyngeus
muscle. Beneath this are the Azygos uvulae and Salpingo-pharyngeus muscles,
consisting of two rounded fleshy fasciculi, placed side by side in the median line
of the soft palate. Next comes the aponeurosis of the Levator palati, joining with
the muscle of the opposite side in the middle line. Fourthly, the anterior fasciculus
of the Palato-pharyngeus, thicker than the posterior, and separating the Levator
palati from the next muscle, the Tensor palati. This muscle terminates in a tendon
which, after winding around the hamular process of the internal pterygoid plate
of the sphenoid bone, expands into a broad aponeurosis in the soft palate, anterior
to the other muscles, which have been enumerated. Finally, we have a thin mus-
cular stratum, the Palato-glossus muscle, placed in front of the aponeurosis of the
Tensor palati, and separated from the oral mucous membrane by adenoid tissue.
The Blood-vessels of the Palate (Fig. 832). — The palate is supplied with blood by
branches of the posterior or descending palatine branch of the internal maxillary artery
(a. palatina descendens] and of the ascending or anterior palatine branch of the facial
artery (a. palatina ascendens). The posterior palatine artery divides into the great
and small palatine arteries (aa. palatinae major et minor), which run through the
1 According to Klein, the mucous membrane on the nasal surface of the soft palate in the foetus is covered
throughout by columnar ciliated epithelium, which subsequently becomes squamous; and some anatomist!
state that it is covered with columnar ciliated epithelium, except at its free margin, throughout life. — ED. of
15th English edition.
THE TONSIL 1223
palatine canals and after emerging give off branches. Branches from the small
palatine go to the soft palate, the large branch passes forward on the hard palate
near the alveolar margin. The ascending palatine branch of the facial lies upon
the medial surface of the Tensor palati muscle and is distributed to the soft palate
and pharynx. A palatine vein corresponding to the descending palatine artery
opens into the anterior facial vein. The pharyngeal veins also receive palatine veins.
The Nerves of the Palate. — The large posterior palatine nerve emerges from the
posterior palatine canal and accompanies the posterior palatine artery. The naso-
palatine nerve emerges from the foramen of Scarpa and is distributed to the anterior
portion of the hard palate. The soft palate is supplied by the small posterior
palatine and the accessory palatine nerves.
The Tonsil or Amygdala (tonsilla palatina) (Figs. 818 and 824). — The tonsils
or amygdalae are two prominent bodies situated one on each side of the fauces,
between the anterior and posterior pillars of the soft palate. They are of a
rounded form, and vary considerably in size in different individuals. A recess,
the supra-tonsillar fossa (fossa supratonsillaris), may be seen, directed upward
and backward above the tonsil. His regards this as the remains of the lower part
of the second visceral cleft. The recess is covered by a fold of mucous mem-
brane termed the plica triangularis. Externally the tonsil is covered with a fibrous
capsule which joins the aponeurosis of the pharynx. The outer surface of the
capsule is in relation with the inner surface of the Superior constrictor muscle
of the pharynx, to the outer side of which is the Internal pterygoid muscle. The
ascending palatine artery is close to the outer surface of the tonsil, the Superior
constrictor muscle of the pharynx and the tonsillar capsule intervening. The
tonsillar artery, which is sometimes a branch of the ascending palatine, is also
close to the outer surface of the tonsil. The internal carotid artery lies behind
and to the outer side of the tonsil, and nearly an inch (20 to 25 mm.) distant from
it. It corresponds to the angle of the lower jaw. The surface of the tonsil
which looks toward the pharynx presents from twelve to fifteen orifices, each
leading into a small recess or crypt (fossula tonsiUaris). From the crypts
numerous follicles branch out into the substance of the tonsil by means of very
irregular channels. The crypts are lined with stratified pavement epithelium.
The epithelium of the crypts exhibits marked degenerative changes. The
degeneration causes the formation of numerous communicating spaces, which
contain leukocytes and lymphocytes. The crypts are surrounded with lymphoid
tissue. In this are numerous lymphoid follicles (noduli lymphatici) , which are
placed in the submucous tissue. These follicles are analogous to those of
Peyer's glands and consist of adenoid tissue. No openings from the capsules
into the follicles can be recognized. They contain a thick grayish secretion.
The Blood-vessels of the Tonsil. — The arteries supplying the tonsils are the
dorsalis linguae from the lingual, the ascending palatine and tonsillar from the
facial, the ascending pharyngeal from the external carotid, the descending palatine
branch of the internal maxillary, and a twig from the parvadural. The veins
terminate in the tonsillar plexus, on the outer side of the tonsil, and the tonsillar
plexus joins the pharyngeal plexus, which communicates with the pterygoid plexus
of the internal jugular or facial vein.
Lymphatics of the Tonsil. — Surrounding each follicle is a close plexus of lym-
phatic vessels. From these plexuses the lymphatic vessels pass to the submaxillary
lymph glands below the angle of the jaw. From the submaxilliary glands lymph
passes to the deep cervical glands.
The Nerves of the Tonsil. — A branch from the glosso -pharyngeal nerve by uniting
with branches of the pharyngeal plexus forms the tonsillar plexus. The pharyn-
geal plexus is formed by the pharyngeal branches of the glosso-pharyngeal and
superior cervical ganglia of the sympathetic and the pharyngeal branch of the vagus.
1224
THE ORGANS OF DIGESTION
The Salivary Glands (Fig. 833).
Numerous glands exist in the lips, cheeks, palate, and tongue, but by the term
salivary glands are usually understood the three chief glandular masses on each
side of the face. These are the principal salivary glands. They communicate
with the mouth, pour their secretion into its cavity, and are named respectively
the parotid, submaxillary, and sublingual.
The Parotid Gland (glandulae parotis). — The parotid gland, so called from being
placed near the ear (nap A, near; o5c, o»roc, the ear}, is the largest of the three
salivary glands, varying in weight from half an ounce to an ounce. It lies upon
the side of the face immediately below and in front of the external ear. It is limited
above by the zygoma ; below, by the angle of the jaw and by a line drawn between
the angle and the mastoid process: anteriorly, it extends to a variable extent
over the Masseter muscle; posteriorly, it is bounded by the external meatus,
the mastoid process, and the Sterno-mastoid and Digastric muscles, slightly
overlapping the two muscles.
FIG. 833.— The salivary glands.
Its anterior surface is grooved to embrace the posterior margin of the ramus of
the lower jaw, and advances forward beneath the ramus, between the two Ptery-
goid muscles and superficial to the ramus over the Masseter muscle. Its outer
surface is triangular and convex, slightly lobulated, is covered by the integument
and parotid fascia, and has one or two lymphatic glands resting on it. Its inner
surface (processus retromandibularis) extends deeply into the neck by means of
two large processes, one of which dips behind the styloid process and projects
beneath the mastoid process and the Sterno-mastoid muscle ; the other is situated
in front of the styloid process, and passes into the back part of the glenoid
fossa, behind the articulation of the lower jaw. The structures passing through
the parotid gland are — the external carotid artery, giving off its three terminal
THE SALIVARY GLANDS 1225
branches: the posterior auricular artery emerges from the gland behind; the super-
ficial temporal artery above; the transverse facial, a branch of the temporal, in front;
and the internal maxillary winds through it as it passes inward, behind the neck
of the jaw. Superficial to the external carotid is the trunk formed by the union
of the temporal and internal maxillary veins; a branch, connecting this trunk
with the internal jugular, also passes through the gland. The gland is also
traversed by the facial nerve and its branches, which emerge at its anterior
border; branches of the great auricular nerve pierce the gland to join the facial,
and the auriculo -temporal branch of the inferior maxillary nerve emerges from the
upper part of the gland. The internal carotid artery and internal jugular vein lie
close to its deep surface. The triangular space occupied by the greater part of
the gland is bounded in front by the posterior margin of the ramus of the jaw
and the internal pterygoid muscle, and behind by the anterior edge of the Sterno-
cleido-mastoid muscle, the tympanic portion of the temporal bone and the car-
tilaginous portion of the external auditory meatus. Its floor is formed by the
anterior and posterior walls of the space which meet about the styloid process.
These walls are composed of fascia derived from the deep cervical fascia. The
remaining side of the space is external and is formed by fascia, derived from the
deep cervical fascia and called the parotid fascia. This space is called the parotid
recess. Sir Frederick Treves1 denies that the fascial covering of the space is
complete. He says it is deficient above between the anterior edge of the styloid
process and the posterior border of the external pterygoid muscle. A portion
of the gland does not occupy the space, but projects forward over the Masseter
muscle. This projecting portion is the facial process.
Lymph -glands, known as the parotid lymph-glands, are in and about the parotid
gland, some being embedded in the outer surface of the parotid fascia, others
being in the inner surface of the fascia, others in the gland itself, particularly
along the temporo-maxillary vein and external carotid artery. They receive
lymph from the anterior and lateral portions of the scalp, both eyelids, a portion
of the cheek, the root of the nose, the outer portion of the external ear, the soft
palate, the posterior nares, and the external auditory meatus. The vessels from
them empty into the superficial cervical glands and the superior deep cervical
glands. Between the parotid gland and the pharynx are the subparotid glands.
They receive lymph from the nasal fossae, naso-pharynx, and Eustachian tube, and
vessels from the glands take lymph to the deep cervical glands.2
The Duct of the Parotid Gland, called the Parotid Duct or Stenson's Duct (ductus
parotideus [Stenonis]) (Fig. 833). — The duct of the parotid gland is about two
inches and a half in length. It commences by numerous branches from the ante-
rior part of the gland, crosses the Masseter muscle, and at its anterior border dips
down into the substance of the Buccinator muscle, which it pierces; it then runs
for a short distance- obliquely forward between the Buccinator muscle and the
mucous membrane of the mouth, and opens upon the inner surface of the cheek
by a small orifice opposite the second molar tooth of the upper jaw (Fig. 824).
Upon the beginning of Stenson's duct there is often an accessory parotid gland
(glandulae parotis accessoria), which is often called the socia parotidis. It is a
portion of the facial process. It is a detached portion of gland, and has a duct
which opens into Stenson's duct. This accessory gland occasionally exists as a
separate lobe, just beneath the zygomatic arch. In this position it has the trans-
verse facial artery above it and some branches of the facial nerve below it.
Surface Form. — The direction of the duct corresponds to a line drawn across the face about
a finger's breadth below the zygoma; that is, from the lower margin of the concha to midway
between the free' margin of the upper lip and the ala of the nose.
1 Applied Anatomy. * Poirier and Cun6o, Human Anatomy.
1226 THE ORGANS OF DIGESTION
Structure of the Parotid Duct. — The parotid duct is dense, it is of considerable
thickness, and its canal is about the size of a crowquill ; but at ks orifice on the
inner aspect of the cheek its lumen is greatly reduced in size. The duct consists
of an external or fibrous coat, of considerable density, containing contractile
fibres, and of an internal or mucous coat lined with short columnar epithelium.
Vessels and Nerves. — The arteries supplying the parotid gland are derived from,
the external carotid, and from the branches given oft' by that vessel in or near its
substance. The veins empty themselves into the external jugular through some
of its tributaries. The lymphatics terminate in the superficial cervical and the
deep cervical glands, passing in their course through several lymphatic glands
placed on the surface and in the substance of the parotid. The nerves are
derived from the plexus of the sympathetic on the external carotid artery, the
facial, the auriculo -temporal, and great auricular nerves. It is probable that the
branch from the auriculo-temporal nerve is derived from the glosso-pharyngeal
through the otic ganglion. At all events, in some of the lower animals this has
been proved experimentally to be the case.
The Parotid Capsule. — The parotid gland is enclosed by two layers of the parotid
fascia (fascia parotideomasseterica) , which almost completely encompass the
gland. The sheath is incomplete at one area toward the pharyngeal wall (see
(p. 1225).
The parotid fascia comes from the deep cervical fascia. The external layer
covers the gland. The internal layer lines the parotid recess. The external layer
is the structure usually spoken of as the parotid fascia. Anteriorly it joins
the fascia of the masseter; below it is continuous with the deep cervical fascia;
above it is attached to the zygoma; behind it is adherent to the external auditory
meatus and sheath of the Sternomastoid. The deep layer is adherent above to the
external auditory meatus and back of the glenoid fossa; internally to the styloid
process; below it is continuous with the deep cervical fascia. The stylomaxillary
or stylomandibular ligament comes off from the parotid fascia.
The Submaxillary Gland (glandula submaxillaris) (Fig. 833). — The submax-
illary gland is situated below the jaw, in the anterior part of the submaxillary
triangle of the neck. It is irregular in form and weighs about two drachms
(8 to 10 grammes). It is covered by the integument, Platysma, deep cervical
fascia, and the body of the lower jaw, corresponding to a depression on the
inner surface of the body of the mandible, and lies upon the Mylo-hyoid, Hyo-
glossus, and Stylo-glossus muscles, a portion of the gland passing beneath the
posterior border of the Mylo-hyoid. In front of it is the anterior belly of the
Digastric muscle; behind, it is separated from the parotid gland by the stylo-
maxillary ligament, and from the sublingual gland in front by the Mylo-hyoid
muscle. The facial artery lies embedded in a groove in its posterior and upper
border. A process is given off from the deep surface of the anterior portion of
the gland. This is the deep process (Cunningham), and it passes with the duct
beneath the Mylo-hyoid muscle.
The Duct of the Submaxillary Gland or Wharton's Duct (ductus submaxillaris
[Whartoni]). — The duct of the submaxillary gland is about two inches in length,
and its walls are much thinner than those of the parotid duct. It commences by
numerous branches from the deep portion of the gland which lies on the upper
surface of the Mylo-hyoid muscle, and passes forward and inward between the
Mylo-hyoid and the Hyo-glossus and Genio-hyo-glossus muscles, then between the
sublingual gland and the Genio-hyo-glossus muscle, and opens by a narrow orifice
on the summit of a small papilla (caruncula sublingualis) at the side of the fraenum
linguae. On the Hyo-glossus muscle it lies between the lingual and hypoglossal
nerves, but at the anterior border of the muscle it crosses under the lingual nerve,
and is then placed above it.
THE SALIVARY GLANDS
1227
Vessels and Nerves. — The arteries supplying the submaxillary gland are branches
of the facial and lingual. Its veins follow the course of the arteries. The lymph-
atics drain into the submaxillary lymph-glands. There are no lymphatic glands
in this salivary gland. The nerves are derived from the submaxillary ganglion,
through which it receives filaments from the chorda tympani and from the lingual
branch of the inferior maxillary, sometimes from the mylo-hyoid branch of the inferior
dental and from the sympathetic.
The Sublingual Gland (glandula sublingualis} (Fig. 833).— The sublingual
gland is the smallest of the salivary glands. It is situated beneath the mucous
membrane of the floor of the mouth, at the side of the fraenum linguae, in contact
with the inner surface of the lower jaw, close to the symphysis. It is narrow,
flattened, in shape somewhat like an almond, and weighs about a drachm. It
is in relation, above, with the mucous membrane; below, with the Mylo-hyoid
muscle; in front, with the depression on the side of the symphysis of the lower
jaw, and with its fellow of the opposite side; behind, with the deep part of the
submaxillary gland; and internally, with the Genio-hyo-glossus, from which it
is separated by the lingual nerve and Wharton's duct. Its excretory ducts or
ducts of Rivinus (ductus sublingualis minores) are from eight to twenty in number.
Crescent of Gianuszi.
Salivary duct.
FIG. 834. — A highly magnified section of the submaxillary gland of the dog, stained with carmine. (Kolliker.)
They open separately into the mouth back of Wharton's duct and upon a fold
of mucous membrane known as the plica sublingualis. The plica sublingualis is
an elevated crest of mucous membrane caused by the projection of the gland on
either side of the fraenum linguae. One or more ducts sometimes join to form
a tube which opens into the Whartonian duct or remains independent, opening
close to Wharton's duct on the sublingual papilla. This single duct is called
the duct of Bartholin (ductus sublingualis major).
Vessels and Nerves. — The sublingual gland is supplied with blood from the
sublingual and submental arteries. Its nerves are derived from the lingual.
Structure of Salivary Glands (Fig. 834). — The salivary glands are compound
racemose glands, consisting of numerous lobes, which are made up of smaller
lobules connected together by dense areolar tissue, vessels, and ducts. Each
lobule consists of the ramifications of a single duct, dividing frequently like the
branches of a tree, the branches terminating in dilated ends or alveoli, on which
the capillaries are distributed. These alveoli, however, as Pfliiger points out,
are not necessarily spherical, though sometimes they assume that form; some-
times they are perfectly cylindrical, and very often they are mutually com-
pressed. The alveoli are enclosed by a basement membrane which is continuous
with the membrana propria of the duct. It presents a peculiar reticulated
1228 THE ORGANS OF DIGESTION
structure, having the appearance of a basket with open meshes, and consisting
of a network of branched and flattened nucleated cells.
The alveoli of the salivary glands are of two kinds, which differ both in the
appearance of their secreting cells, in their size, and in the nature of their secre-
tion. The one variety secretes a ropy fluid which contains mucin, and such
alveoli have therefore been named the mucous alveoli, whilst the other secretes a
thinner and more watery fluid, which contains serum-albumin, and alveoli of
this variety have been named serous or albuminous alveoli. The sublingual gland
may be regarded as an example of the former variety, the parotid of the latter.
The submaxillary is of the mixed variety, containing both mucous and serous
alveoli, the latter, however, preponderating.
Both varieties of alveoli are lined by cells, and it is by the character of these
cells that the nature of the gland is chiefly to be determined. In addition, how-
ever, the alveoli of the serous glands are smaller than those of the mucous ones.
The Mucous Alveoli. — The cells in the mucous alveoli are spheroidal in shape,
glassy, transparent, and dimly striated in appearance. The nucleus is usually
situated in the part of the cell which is next the basement membrane, against
which it is sometimes flattened. The most remarkable peculiarity presented by
these cells is, that they give off an extremely fine process which is curved in a
direction parallel to the surface of the alveolus, lies in contact with the membrana
propria, and overlaps the process of neighboring cells. The cells contain a quan-
tity of inucin, to which their clear, transparent appearance is due.
Here and there in the alveoli are seen peculiar half-moon-shaped bodies lying
between the cells and the membrana propria of the alveolus. They are termed
the crescents of Gianuzzi or the demilunes of Heidenhain (Fig. 834), and are com-
posed of polyhedral granular cells, which Heidenhain regards as young epithelial
cells destined to supply the place of those salivary cells which have undergone
disintegration. This view, however, is not accepted by Klein.
Serous Alveoli. — In the serous alveoli the cells almost completely fill the cavity,
so that there is hardly any lumen perceptible. Instead of presenting the clear,
transparent appearance of the cells of the mucous alveoli, they present a granular
appearance, due to distinct granules of an albuminous nature embedded in a closely
reticulated protoplasm. The ducts which originate from the alveoli are lined at
their commencement by epithelium which differs little from the pavement type.
As the ducts enlarge, the epithelial cells change to the columnar type, and the part
of the cells next the basement-membrane is finely striated. The lobules of the
salivary glands are richly supplied with blood-vessels which form a dense network
in the interalveolar spaces. Fine plexuses of nerves are also found in the inter-
lobular tissue. The nerve-fibnls pierce the basement-membrane of the alveoli,
and end in branched varicose filaments between the secreting cells. There is no
doubt that ganglia are to be found in some salivary glands in connection with the
nerve-plexuses in the interlobular tissue; they are to be found in the submaxillary,
but not in the parotid.
In the submaxillary and sublingual glands the lobes are larger and more loosely
united than in the parotid.
Mucous Glands. — Besides the salivary glands proper, numerous other glands
are found in the mouth. They appear to secrete mucus only, which serves to keep
the mouth moist during the intervals of the salivary secretion, and which is mixed
with that secretion in swallowing. Many of these glands are found at the posterior
part of the dorsum of the tongue, behind the circumvallate papillae, and also along
its margins as far forward as the apex.1 Others lie around and in the tonsil
pa.
assist in the more rapid di
the sense of taste is situated. — ED. of 15th English edition.
THE SALIVARY GLANDS 1229
between its crypts, and a large number are present in the soft palate. These
glands are of the ordinary compound racemose type. Behind the tip of the
tongue on each side, external to the anterior extremity of the genio-glossus muscle,
is a mucous gland, the gland of Nuhn and Blandin (glandula lingualis anterior}.
Its lower surface is partly covered by muscular fibres from the inferior lingualis
and styloglossus muscles, and it opens by several ducts.
Surface Form.— The orifice of the mouth is bounded by the lips, two thick, fleshy folds
covered externally by integument and internally by mucous membrane, and consisting of
muscles, vessels, nerves, arcolar tissue, and numerous small glands. The size of the orifice of
the mouth varies considerably in different individuals, but seems to bear a close relation to the
size and prominence of the teeth. Its corners correspond pretty accurately to the outer border
of the canine teeth. In the Ethiopian tribes the front teeth are large and inclined for-
ward, the mouth is large; and this, combined with the thick and everted lips which appear to
be associated with prominent teeth, gives to the negro's face much of the peculiarity by which
it is characterized. The smaller teeth and the slighter prominence of the alveolar arch of the
more highly civilized races render the orifice of the mouth much smaller, and thus a small
mouth is an indication of intelligence, and is regarded as an evidence of the higher civilization
of the individual.
Upon looking into the mouth, the first thing we may note is the tongue, the upper surface
of which will be seen occupying the floor of the cavity. This surface is convex, and is marked
along the middle line by a raphe which divides it into two symmetrical portions. The anterior
two-thirds is rough and studded with papillae; the posterior third smooth and tuberculated,
and covered by numerous glands which project from the surface. Upon raising the tongue
the mucous membrane which invests the upper surface may be traced covering the sides of the
under surface, and then reflected over the floor of the mouth on to the inner surface of the
lower jaw, a part of which it covers. As it passes over the borders of the tongue it changes its
character, becoming thin and smooth and losing the papillae which are to be seen on the upper
surface. In the middle line the mucous membrane on the under surface of the tip of the tongue
forms a distinct fold, the fraenum linguae, by which this organ is connected to the symphysis
of the jaw. Occasionally it is found that this fraenum is rather shorter than natural, and,
acting as a bridle, prevents the complete protrusion of the tongue. When this condition exists
and an attempt is made to protrude the organ, the tip will be seen to remain buried in the
floor of the mouth, and the dorsum of the tongue is rendered very convex, and more or less
extruded from the mouth; at the same time a deep furrow will be noticed to appear in the
middle line of the anterior part of the dorsum. Sometimes, a little external to the fraenum,
the ranine vein may be seen immediately beneath the mucous membrane. The corresponding
artery, being more deeply placed, does not come into view, nor can its pulsation be felt with the
finger. On either side of the fraenum, in the floor of the mouth, is a longitudinally elevation or
ridge, produced by the projection of the sublingual gland, which iies immediately beneath the
mucous membrane. And close to the attachment of the fraenum to the tip of the tongue may
be seen on either side the slit-like orifices of Wharton's ducts, into which a fine probe may be
passed without much difficulty. By everting the lips the smooth mucous membrane lining them
may be examined, and may be traced from them on to the outer surface of the alveolar arch.
In the middle line, both of the upper and lower lip, a small fold of mucous membrane passes
from the lip to the bone, constituting the fraena; these are not so large as the fraenum linguae.
By pulling outward the angle of the mouth, the mucous membrane lining the cheeks can be
seen, and on it may be perceived a little papilla which marks the position of the orifice of Sten-
son's duct — the duct, of the parotid gland. The exact position of the orifice of the duct will be
found to be opposite the second molar tooth of the upper jaw. The introduction of a probe
into this duct is attended with considerable difficulty. The teeth are the next objects which
claim our attention upon looking into the mouth. These are, as stated above, ten in either jaw
in the temporary set, and sixteen in the permanent set. The gums, in which they are implanted,
are dense, firm, and vascular.
At the back of the mouth is seen the isthmus of the fauces, or, as it is popularly called, " the
throat:" this is the space between the pillars of the fauces on either side, and is the means
by which the mouth communicates with the pharynx. Above, it is bounded by the soft palate,
the anterior surface of which is concave and covered with mucous membrane, which is con-
tinuous with that lining the roof of the mouth. Projecting downward from the middle of
its lower border is a conical-shaped projection, the uvula. On either side of the isthmus of the
fauces are the anterior and posterior pillars, formed by the Palato-glossus and Palato-pharyn-
geus muscles respectively, covered over by mucous membrane. Between the two pillars on eitner
side is situated the tonsil. The extirpation of this body is not unattended with danger of
hemorrhage. Dr. Weir has stated that he believes that when hemorrhage occurs after their
removal it arises from one of the palatine arteries having been wounded. These vessels are
1230 THE ORGANS OF DIGESTION
large: they lie in the muscular tissue of the palate, and when wounded are constantly exposed
to disturbance from the contraction of the palatine muscles. The vessels of the tonsil, Dr. Weir
states, are small and lie in the soft tissue, and readily contract when wounded.
When the mouth is wide open a prominent tense fold of mucous membrane may be seen and
felt, extending upward and backward from the position of the fang of the last molar tooth
to the posterior part of the hard palate. This is caused by the pterygo-maxillary ligament,
which is attached by one extremity to the apex of the internal pterygoid plate, and by the other
to the posterior extremity of the mylo-hyoid ridge of the lower jaw. It connects the Buccinator
with the Superior constrictor of the pharynx. The fang of the last molar tooth indicates the
position of the lingual (gustatory) nerve where it is easily accessible, and can with readiness
be divided in cases of cancer of the tongue (see page 1043). On the inner side of the last molar
tooth we can feel the hamular process of the internal pterygoid plate of the sphenoid bone,
around which the tendon of the Tensor palati plays. The exact position of this process is of
importance in performing the operation of siaphylorrhaphy . About one-third of an inch in
front of the hamular process, and the same distance directly inward from the last molar tooth,
is the situation of the opening of the posterior palatine canal, through which emerges the pos-
terior or descending palatine branch of the internal maxillary artery and one of the descending
palatine nerves from Meckel's ganglion. The exact position of the opening on the subject may
be ascertained by driving a needle through the tissues of the palate in this situation, when it
will be at once felt to enter the canal. The artery emerging from the opening runs forward in a
groove in the bone just internal to the alveolar border of the hard palate, and may be wounded
in the operation for the cure of cleft palate. Under these circumstances the palatine canal may
require plugging. By introducing the finger into the mouth the anterior border of the coronoid
process of the jaw can be felt, and it is especially prominent when the jaw is dislocated. By
throwing the head well back a considerable portion of the posterior wall of the pharynx may be
seen through the isthmus faucium, and on introducing the finger the anterior surface of the
bodies of the upper cervical vertebrae may be felt immediately beneath the thin muscular
stratum forming the wall of the pharynx. The finger can be hooked around the posterior
border of the soft palate, and by turning it forward the posterior nares, separated by the
septum, can be felt, or the presence of any adenoid or other growths in the naso-pharynx can
be ascertained.
THE PHARYNX (Figs. 831, 837, 838).
The pharynx (from (pdpuys, the throat] is that part of the alimentary canal
which is placed behind and communicates with the nose, mouth, and larynx. It
is a musculo-membranous tube, somewhat conical in form, with the base upward
and the apex downward, extending from the under surface of the skull to the level
of the cricoid cartilage in front and that of the intervertebral disk between the fifth
and sixth cervical vertebrae behind.
The pharynx is about four inches and a half in length, and broader in the trans-
verse than in the antero-posterior diameter. Its greatest breadth is opposite the
cornua of the hyoid bone ; its narrowest point, at its termination in the oesophagus.
It is attached, above, to the periosteum of the petrous portion of the temporal
bone and of the basilar process of the occipital bone. To the pharyngeal tubercle
of the basilar process of the occipital bone the raphe of the Constrictor muscles is
attached. It is bounded above by the body of the sphenoid as well as by the basilar
process of the occipital ; below, it is continuous with the oesophagus ; posteriorly, it
is connected by loose areolar tissue with the cervical portion of the vertebral
column and the Longi colli and Recti capitis antici muscles; this areolar tissue is
contained in what is called the retro-pharyngeal space (spatia retropharyngeus] ;
anteriorly, it is incomplete, the gap being occupied by the cavities of the nose,
mouth, and larynx. Anteriorly, it is attached in succession to the Eustachian tube,
the internal pterygoid plate, the pterygo-maxillary ligament, the posterior termi-
nation of the mylo-hyoid ridge of the lower jaw, the mucous membrane of the
mouth, the base of the tongue, hyoid bone, the thyroid and cricoid cartilages;
laterally, it is connected to the styloid processes and their muscles, and is in con-
tact with the common and internal carotid arteries, the internal jugular veins,
and the glosso-pharyngeal, vagus, hypoglossal, and sympathetic nerves, and
above with a small part of the Internal pterygoid muscles. When the pharynx
THE PHARYNX
1231
is at rest the anterior and posterior walls are near together. Above the larynx
they do not come in contact, but leave a channel for air; below the larynx they
lie in contact, but open for the passage of food. It has seven openings com-
municating with it — the two posterior nares, the two Eustachian tubes, the
mouth, larynx, and oesophagus. The pharynx may be subdivided from above
downward into three parts, nasal, oral, and laryngeal.
The Nasal Part (pars nasalis pharyngis) (Fig. 837). — The nasal part of the
pharynx or naso-pharynx lies behind the nose and above the level of the soft palate;
it differs from the two lower parts of the tube in that its cavity always remains
patent. In front it communicates through the posterior nares (choanae) (Fig. 838)
with the nasal fossae. On its lateral wall is the pharyngeal orifice of the Eustachian
tube (ostium pharyngeum tubae auditivae) (Figs. 835 and 836), which presents the
appearance of a vertical or triangular cleft bounded above and behind by a firm
prominence. The anterior portion of the prominence (labium anterius)is the smaller
portion. The posterior portion (labium posterius) is large and thick, is called the
Eustachian cushion (torus tubarius), and is caused by the inner extremity of the car-
tilage of the tube impinging on the deep surface of the mucous membrane (Fig. 836) .
A vertical fold of mucous membrane, the salpingo-pharyngeal fold (plica salpingo-
ORIFICE OF
EUSTACHIAN
TUBE
PHARYNGEAL
BURSA
FIG. 835. — Pharyngeal tonsil in an adult.
(Eacat.)
SALPINGO-
NASAL FOLD
EUSTACHIAN
CUSHION
SALPINGO
PALATINE FOLD
SALPINGO-PHARYN-
GEAL FOLD
FIG. 836. — The posterior lateral cavity of the naso-
pharynx. (Escat.)
pharyngea) (Fig. 836), stretches from the lower part of the cushion to the pharynx;
it contains the Salpingo-pharyngeus muscle. A second and smaller mucous fold
may be seen stretching from the upper part of the cushion to the palate, the
salpingo-palatine fold (plica salpingopalatina) (Fig. 836). Behind the orifice of the
Eustachian tube is a deep recess, the lateral recess or fossa of Rosenmtiller (recessus
pharyngeus) (Fig. 836), which represents the remains of the upper part of the sec-
ond branchial cleft. The posterior wall of the naso-pharynx is directed upward and
forward, and it meets the superior wall at an angle. This rounded area of meet-
ing is the vault of the pharynx (fornix pharyngis). On the posterior wall, at the
level and above the level of the orifices of the Eustachian tubes, there is a col-
lection of lymphoid tissue. This is particularly marked in children, and almost
or quite disappears in the aged. Over it the mucous membrane is thick and
in folds. This collection of lymphoid tissue is the pharyngeal tonsil (fonsilla
pharyngea) (Fig. 835). The naso-pharynx communicates with the oral pharynx
through an aperture between the soft palate and the posterior pharyngeal wall.
This aperture is the isthmus of the pharynx (isthmus pharyngonasalis).
The Oral Part (pars oralis pharyngis). — The oral part of the pharynx reaches
from the soft palate to the level of the hyoid bone. It opens anteriorly, through
the isthmus faucium, into the mouth, while in its lateral wall, between the two
1232
THE ORGANS OF DIGESTION
pillars of the fauces, is the tonsil. A triangular area on the lateral wall is known as
the sinus tonsillaris (Fig. 837) . It is bounded anteriorly by the anterior palatine
arch, posteriorly by the posterior palatine arch, and below by the side of the
pharyngeal portion of the tongue.
The Laryngeal Part (pars laryngea pharyngis). — The laryngeal part of the
pharynx is that division which lies behind the larynx ; it is wide above where it is con-
tinuous with the oral portion while below at the lower border of the cricoid cartilage
it becomes continuous with the oesophagus. In front it presents the triangular
aperture of the larynx, the base of which is directed forward and is formed by the
epiglottis, while its lateral boundaries are constituted by the aryteno-epiglottidean
folds. On either side of the laryngeal orifice is a recess, termed the sinus pyri-
OPENING OF
STENSON'S
DUCT
GENIO-
HVOGLOSSUS
MUSCLE
BURSA BENEATH
HYOID BONE
THYROID
CARTILAGE
CRICOID
CARTILAGE
PHARYNGEAL
BURSA
ORIFICE OF
EUSTACHIAN TUBE
PHARYNGEAL
TONSIL
SOFT PALATE
NASOPHARYNX
ANTERIOR PALA-
TINE ARCH
POSTERIOR PALA-
TINE ARCH
TONSIL
CAVITY OF
PHARYNX
TONSILLAR
SINUS
POSTERIOR PALA-
TINE ARCH
EPIGLOTTIS
SINUS
-PYRIFORMIS
ARYTENO-
E PI GLOTTIC
FOLD
CUNEIFORM
CARTILAGE
ARYTENOID
CARTILAGE
OESOPHAGUS
RING OF
TRACHEA
FIG. 837. — Sagittal median section of the head and neck. The head is thrown backward into complete extension,
which explains the relations between the lower jaw and the hyoid bone as seen in the figure. (Luschka.)
formis (recessus piriformis) (Fig. 837); it is bounded internally by the aryteno-
epiglottidean fold, externally by the thyroid cartilage and thyro-hyoid membrane.
In the anterior part of the sinus pyriformis is a fold (plica uervi laryngei), which
passes downward and inward. Extending outward from the epiglottis on each
side is a fold, the pharyngo-epiglottic fold (plica pharyngoepiglottica). This ascends
in the lateral wall of the pharynx, nearly to the posterior arch of the fauces.
Structure. — The constrictors of the pharynx (see p. 402) are surrounded by
a sheath of thin fascia, the bucco-pharyngeal fascia (Cunningham). Forward pro-
THE PHARYNX
1233
longations of this fascia overlay the Buccinator muscles. The connective tissue of
the retro-pharyngeal space joins the bucco-pharyngeal fascia to the prevertebral
fascia, and it is attached by areolar tissue to the other structures to which the
pharynx is in contact (Cunningham). The pharynx is composed of three coats
— fibrous, mucous and muscular.
The Pharyngeal Aponeurosis or Fibrous Coat is situated between the mucous
and muscular layers. It is thick above, where the muscular fibres are wanting, and
is firmly connected to the periosteum of the basilar process of the occipital and
petrous portion of the temporal bones. It is united to the Eustachian tube, pos-
terior nares, and other points which the pharynx joins. It is thicker above than
below, and above the sinuses of Morgagni there is no muscular coat, and the wall
FIG. 838. — The anterior surface of the pharynx. (Sappey.)
of the pharynx is composed of aponeurosis and mucous membrane. As it descends
it diminishes in thickness, and is gradually lost. It is strengthened posteriorly by
a strong fibrous band which is attached above to the pharyngeal spine on the under
surface of the basilar portion of the occipital bone, and passes downward, forming
a median raphe, which gives attachment to the Constrictor muscles of the pharynx.
The Mucous Coat (tunica mucosa). — The mucous coat is continuous with that
lining the Eustachian tubes, the nares, the mouth, and the 'larynx. In the naso-
pharynx it is covered by columnar ciliated epithelium; in the buccal and laryngeal
portions the epithelium is of the squamous variety. Beneath the mucous membrane
are found racemose mucous glands (glandulae pharyngeae) ; they are especially
numerous at the upper part of the pharynx around the orifices of the Eustachian
tubes. Throughout the pharynx are also numerous crypts or recesses, the walls,
;< a
1234 THE ORGANS OF DIGESTION
of which are surrounded by lymphoid tissue similar to that found in the tonsils.
Across the back part of the pharyngeal cavity, between the two Eustachian tubes,
a considerable mass of this tissue exists, and has been named the pharyngeal tonsil
(Fig. 835). Above this in the middle line is an irregular, flask-shaped depres-
sion of the mucous membrane, extending up as far as the basilar process of the
occipital bone. It is known as the pharyngeal bursa (bursa pharyngea), and was
regarded by Luschka as the remains of the diverticulum, which is concerned in
the development of the anterior lobe of the pituitary body. Other anatomists
believe that it is connected with the formation of the pharyngeal tonsils. The
muscular coat (tunica muscularis pharyngis) has been already described (p. 402).
The sinuses of Morgagni, referred to on a previous page (p. 404), are intervals
between the Superior constrictor muscles and the basilar process of the occipital
bone.
The Lymphatic Pharyngeal Ring. — This name was applied by Waldeyer to the
lymphatic structure gathered into a sort of ring about the pharynx. There are
three chief collections of this tissue on each side. The first is known as the lingual
tonsil (p. 1098); the second as the palatine tonsil (p. 1222); and the third as the
pharyngeal tonsil (p. 1231).
Surgical Anatomy of the Mouth, Cheeks, Lips, Gums, Tonsils, Palate, Salivary Glands,
and Pharynx. — The duct of a salivary gland may be blocked by a calculus, and the condition
is often productive of severe pain.
A wound of Stenson's duct or of the parotid gland may be followed by a salivary fistula.
The parotid recess is completely lined by fascia, except above. "Between the anterior edge
of the styloid process and the posterior border of the external pterygoid muscle there is a gap
in the fascia, through which the parotid space communicates with the connective tissue about
the pharynx."1
This explains why there is frequently swelling of the parotid region in post-pharyngeal abscess.
A parotid abscess rarely bursts through the skin; it may pass into the temporal fossa, may
enter the zygomatic fossa, may advance toward the mouth, pharynx, or neck. Because of the
situation of thj gland, a parotid abscess may cause inflammation of the temporo-mandibular
joint or periostitis of the bone about the meatus, and may even burst into the external auditory
meatus (Treves).
The facial nerve passes through the gland, and inflammation or tuberculosis of the gland
may cause facial palsy. Some enlargements of the parotid region are due to inflammation of
the parotid lymph-glands, and these glands may become tuberculous.
Mumps is characterized by acute inflammation of the parotid gland.
Various tumors occur in the parotid (fibroma, sarcoma, carcinoma, enchondroma, etc.).
Most parotid tumors contain more or less cartilage. Complete extirpation of the parotid gland
surgically is certainly extremely difficult, and Treves and others maintain that it is impossible.
Ranula is a salivary cyst of the floor of the mouth, due to occlusion of ducts of the sublingual
gland or the duct of the submaxillary gland. Mucous cysts occur in the mouth. A mucous cyst
of the gland of Nuhn and Blandin is on the under surface of the tongue near the apex. A
dermoid cyst of the base of the tongue is occasionally encountered. It is of congenital origin.
What is known as the sublingual bursa is an epithelial-lined space, said to exist between
the mucous membrane of the floor of the mouth and the Genio-hyo-glossus muscle. When
acutely inflamed, it produces rapidly a marked swelling called acute ramda. Incomplete
closure of the oral end of the thyro-glossal duct causes thyro-glossal fistula. If the oral end closes,
but a portion of the duct below remains unobl iterated, a thyro-glossal cyst forms. Such a cyst
or fistula is always in the median line. The reader will remember that this duct runs from the
foramen caecum to the isthmus of the thyroid gland.
Hare-lip is considered on pp. 110 and 111.
The lower lip, more commonly than any other structure, gives origin to cancer. The upper
lip is not nearly so often affected. Blocking of mucous glands of the lips causes mucous cysts.
A scar of the lip or about the lip disturbs this structure and pulls it far out of place. Thus
great deformity is produced. Burns particularly induce hideous cicatricial contraction.
Plastic operations in this region are often successful, because of the great vascularity of the
parts, and because adjacent parts admit -of being stretched and pulled in.
Cleft palate is a by no means rare congenital deformity. The cleft is in the middle line.
It may be a mere cleft of the uvula, it may be limited to the soft palate, or it may involve
1 Applied Anatomy. By Sir Frederick Treves.
THE OESOPHAGUS 1235
the hard palate to but not including the alveolus. It may pass through the alveolus, but if it
does so it ceases to be median at this point, and follows the line of suture between the incisive
bone and the superior maxillary (pp. 110 and 111). In a complete cleft palate there is apt
to be hare-lip at the end of the palate cleft. This cleft in the lip is not median, but is at the
termination of the palate cleft. If the cleft of a cleft palate runs along each side of the
incisive bone, the bone is isolated from the superior maxillary. In such a case double hare-lip
results.
When a tonsil enlarges it projects inward. The deafness which so often attends hypertrophy
of the tonsil is not due to blocking of the Eustachian orifice by the tonsil, but is due to thicken-
ing of the mucous membrane lining the tube itself. The profuse bleeding which sometimes
follows an operation for the removal of the tonsil is very seldom due to injury of the internal,
carotid artery, but is due to injury of the ascending pharyngeal artery (p. 623) or one of the
palatine arteries.
The internal carotid artery is in close relation with the pharynx, so that its pulsations can
be felt through the mouth. It has been occasionally wounded by sharp-pointed instruments
introduced into the mouth and thrust through the wall of the pharynx. In aneurism of this
vessel in the neck the tumor necessarily bulges into the pharynx, as this is the direction in
which it meets with the least resistance, nothing lying between the vessel and the mucous
membrane except the thin Constrictor muscle, whereas on the outer side there is the dense
cervical fascia, the muscles descending from the styloid process, and the margin of the Sterno-
mastoid muscle.
The mucous membrane of the pharynx is very vascular, and is often the seat of inflamma-
tion, frequently of a septic character, and dangerous on account of its tendency to spread to the
larynx. On account of the tissue which surrounds the pharyngeal wall being loose and lax, the
inflammation is liable to spread through it far and wide, extending downward into the posterior
mediastinum along the oesophagus. Abscess may form in the connective tissue behind the
pharynx, between it and the vertebral column, constituting what is known as retro-pharyngeal
abscess. This is most commonly due to caries of the cervical vertebrae, but may also be caused
by suppuration of a lymphatic gland which is situated in this position opposite the axis, and
which receives lymphatics from the nares, or by gumma or by acute pharyngitis. In these
cases the pus may be easily evacuated by an incision, with a guarded bistoury, through the
mouth, but; for aseptic reasons, it is desirable that the abscess should be opened from the neck.
In some instances this is perfectly easy; the abscess can be felt bulging at the side of the neck
and merely requires an incision for its relief; but this is not always so, and then an incision
should be made along the posterior border of the Sterno-mastoid and the deep fascia should
be divided. A director is now to be inserted into the wound, the forefinger of the left hand
being introduced into the mouth and pressure made upon the swelling. This acts as a guide,
and the director is to be pushed onward until pus appears in the groove. A pair of sinus forceps
are now inserted along the director and the opening into the cavity dilated.
Foreign bodies not infrequently become lodged in the pharynx and most usually at its termi-
nation at about the level of the cricoid cartilage, just beyond the reach of the finger, as the
distance from the arch of the teeth to the commencement of the oesophagus is about six inches.
Hypertrophy of the adenoid tissue of the naso-pharynx produces groups of hypertrophic
masses known as adenoids. A child with adenoids has a cough, and when awake or asleep,
breathes noisily and with the mouth open. The voice is muffled, the hearing is impaired, the
expression is vacant, the mind is dull, and the tonsils are enlarged.
THE OESOPHAGUS (Figs. 839, 840, 841, 842).
The oesophagus (oi'to, oi'oto, I carry; <paf£iu, to eat} or gullet is a muscular
canal, averaging about nine or ten inches in length, extending from the pharynx
to the stomach. It commences at the upper border of the cricoid cartilage, oppo-
site the intervertebral disk between the fifth and sixth cervical vertebrae, descends
along the front of the spine through the posterior mediastinum, passes through
the Diaphragm, and, entering the abdomen, terminates in the stomach wall at the
point known as the cardia opposite the tenth thoracic vertebra or possibly opposite
the intervertebral disk between the tenth and eleventh thoracic vertebrae. The
general direction of the oesophagus is vertical, but it presents two or three slight
curves in its course. At its commencement it is placed in the median line, but
it inclines to the left side as far as the root of the neck, gradually passes to the
middle line again, and finally again deviates to the left as it passes forward to
1236
THE ORGANS OF DIGESTION
the oesophageal opening of the Diaphragm (hiatus oesophageus) . The oesophagus
also presents an antero-posterior flexure, corresponding to the curvature of the
cervical and thoracic portions of the spine. It is the narrowest part of the alimen-
tary canal, being most contracted at its commencement and at the point where
it passes through the Diaphragm.
The diameter of the largest portion of the oesophagus where it is contracted is
about half an inch; when it is fully dilated, an inch or even more.
In the neck the oesophagus, when at rest, is flattened, the anterior and posterior
• walls approaching each other. The canal in the neck is round or oval, and the
lumen is stellate (Cunningham). The oesophagus is somewhat constricted at three
points. One constriction is at the very beginning of the tube; another is where
the left bronchus crosses it; another is at the point where the oesophagus passes
through the Diaphragm. The tube at each constricted point is distinctly flattened.
The diameter of each of these constricted parts is slightly under one-half inch,
the diameter of the rest of the tube when contracted is one-half inch, but when
dilated may reach or exceed one inch. The average distance from the upper
AZYGOS VEIN
FIG. 839.— Pleural cul-de-sac of the posterior mediastinum.
incisor teeth to the beginning of the gullet is about six inches; the average distance
from the incisor teeth to the cardiac opening of the stomach is fifteen or sixteen
inches. The portion of the oesophagus which is in the neck is called the cervical
portion (pars cervicalis) ; the portion in the thorax, the thoracic portion ( pars thora-
calis), and the portion which lies in the oesophageal opening of the Diaphragm,
the diaphragmatic portion. The margin of the oesophageal orifice in the Diaphragm
is narrow in front, thicker behind and to the sides. Behind and to the sides the
diaphragmatic portion of the oesophagus is about half an inch in length. In
front there is only a thin edge of Diaphragm in contact with the gullet. The
oesophagus is connected to the margins of the diaphragmatic orifice by connec-
tive tissue. The so-called abdominal portion of the oesophagus (pars abdominalis)
is not over half an inch in length, and is limited to the small portion of the ante-
rior and left lateral surface observed when a stomach which is completely
empty is drawn downward with considerable force. The abdominal portion of
the oesophagus is covered with peritoneum; the corresponding portions of the
right lateral and posterior walls are not covered by peritoneum. This uncov-
ered portion of the oesophagus runs downward and to the left and lies directly
THE OESOPHAGUS
1237
.OESOPHAGUS
behind the oesophageal groove on the posterior surface of the left lobe of the
liver, but does not actually touch the groove, which in reality holds, the thick,
right edge of the oesophageal opening of the Diaphragm. When the stomach is
distended the abdominal portion of the gullet ceases to exist and becomes part
of the stomach wall.
Relations. — In the neck the oesophagus is in relation, in front, with the trachea,
and it is connected to the posterior wall of the trachea by areolar tissue. At the
lower part of the neck, where it projects to the left
side, it is in relation in front with the thyroid gland
and thoracic duct; behind, it rests upon the vertebral
column and Longi colli muscles; on each side, it is in
relation with the common carotid artery (especially the
left, as the gullet inclines to that side) and part of the
lateral lobes of the thyroid gland; the recurrent laryn-
geal nerves ascend between it and the trachea.
In the thorax, it is at first situated a little to the left
of the median line; it then passes behind the aortic
arch, being separated from it by the trachea, and de-
scends in the posterior mediastinum, along the right
side of the aorta, nearly to the Diaphragm, where it
passes in front and a little to the left of the artery,
previous to entering the abdomen. It is in relation,
in front, with the trachea, the arch of the aorta, the
left common carotid and left subclavian arteries, which
incline toward its left side, the left bronchus, the
pericardium, and the Diaphragm; behind, it rests
upon the vertebral column, the Longi colli muscles,
the right intercostal arteries, and the vena azygos
minor; and below, near the Diaphragm, upon the front
of the aorta; laterally, it comes in contact with both
pleurae, especially with the left pleura above and the
right pleura below; it overlaps the vena azygos major,
which lies on its right side, while the descending aorta
is placed on its left side. The vagus nerves descend
in close contact with it, the right nerve passing down
behind, and the left nerve in front of it, each nerve
spreading out into a plexus, the oesophageal plexus,
around the tube. The two plexuses are joined to each
other. The right nerve forms the posterior oesophageal
plexus (plexus oesophageus posterior); the left nerve
the anterior oesophageal plexus (plexus oesophageus
anterior).
In the lower part of the posterior mediastinum the
thoracic duct lies to the right side of the oesophagus; higher up, it is placed
behind it, and, crossing about the level of the fourth thoracic vertebra, is continued
upward on its left side.
Above the aortic arch and the arch of the great azygos vein above the root
of the right lung, the pleurae are close to but not in actual contact with the
oesophagus.
Below the arch of the great azygos vein the right side of the oesophagus is
covered with pleura nearly to the diaphragmatic opening. The posterior surface
of the gullet also may be covered with pleura. Below the arch of the aorta on
the left side the pleura covers only a small portion of the oesophagus, that is, a
portion of the left wall, a little above the diaphragmatic opening,
.DIAPHRAGM
FIG. 840.— The supports of the
oesophagus at the aorta in an in-
fant. (Poirier and Charpy.)
1238
THE ORGANS OF DIGESTION
Anomalies. — There may be openings of the oesophagus into the trachea. A
diverticulum or pressure pouch may exist. Such a pouch is usually placed upon
the posterior wall near the pharynx. There may be congenital constriction, tubular
or annular.
Structure. — The oesophagus is fastened to adjacent structures by connective
tissue called the tunica adventitia. The tube has three coats — an external or
muscular, a middle or areolar, and an internal or mucous coat.
The Muscular Coat (tunica muscularis}. — The muscular coat is composed of two
planes of fibres of considerable thickness, an external plane of longitudinal and
an internal plane of circular fibres.
LEFT
PULMONARY
ARTERY
LEFT LUNG
LEFT BRONCHI
THORACIC CANAL'
VAGUS NERVE
AZYGOS VEIN
SUPERIOR LARYN-
GEAL NERVE
INTERNAL
JUGULAR VEIN
' TRACHEA
NFERIOR
THYROID ARTERY
RECURRENT
NERVE
SUBCLAVICULAR
ARTERY
RIGHT CEPHALIC-
TRUNK
•OESOPHAGUS
VAGUS NERVE
AZYGOS VEIN
RONCHIAL
ARTERY
| RIGHT PUL-
[— MONARY VEIN:
FIG. 841. — The position and relation of the oesophagus in the cervical region and in the posterior mediastinum.
Seen from behind. (Poirier and Charpy.)
The Longitudinal Fibres are arranged, at the commencement of the tube, in three
fasciculi: one in front, which is attached to the vertical ridge on the posterior
surface of the cricoid cartilage; and one at each side, which is continuous with
the fibres of the Inferior constrictor of the pharynx ; as they descend they
blend together and form a uniform layer, which covers the outer surfaae of the
tube.
Accessory slips of muscular fibres are described by Cunningham as passing
between the oesophagus and the left pleura (m. pleurooesophageus), where it covers
the thoracic aorta, or between the oesophagus and the root of the left bronchus
(m. bronchooesophageus) , or the back of the pericardium, as well as other still more
THE OESOPHAGUS
1239
rare accessory fibres. In Fig. 842, taken from a dissection in the Museum of the
Royal College of Surgeons of England, several of these accessory slips may be seen
passing from the oesophagus to the pleura, and two slips passing to the back of
the trachea just above its bifurcation. These slips of muscular fibres which pass
to adjacent structures give support to the oesophagus. Below, the longitudinal
fibres of the oesophagus are continued into the longitudinal fibres of the stomach.
The Circular Fibres are continuous above with the Inferior constrictor of the
pharynx; their direction is transverse at the upper and lower parts of the tube,
but oblique in the central part. Below, the circular fibres pass into the circular
and oblique fibres of the stomach.
The muscular fibres in the upper part of the oesophagus are of a red color, and
consist chiefly of the striped variety, but below they consist for the most part of
involuntary muscular fibre. At the cardia they act
as a sphincter to solid food. Some maintain that
this sphincter is closed tonically, others that it opens
and closes rhythmically during gastric digestion.
The Submucous or Areolar Coat (tela submucosa).—
The submucous or areolar coat connects loosely the
mucous and muscular coats. It consists of dense
connective tissue and contains blood-vessels, nerves,
and oesophageal glands (glandulae oesophageae). The
glands are mucous glands and are found through-
out the length of the gullet. The ducts of the glands
pass through the muscularis mucosae. These ducts
are surrounded by adenoid tissue.
The Mucous Coat (tunica mucosa). — The mucous
coat is thick, of a reddish color above and pale
below. It is disposed in longitudinal folds, which
disappear on distention of the tube. Its surface is
studded with minute papillae, and is covered through-
out with a thick layer of stratified pavement epithe-
lium. The mucous coat contains glands which differ
from the mucous glands of the submucous tissue.
They are branched and tubular (Hewlett) and are
called the superficial glands. There are two chief
groups of superficial glands; one near the beginning,
and the other near the termination of the oesophagus.
The ducts of the superficial glands are not sur-
rounded by lymphoid tissue (Hewlett). Beneath the
mucous membrane, between it and the submucous
coat, is a layer of longitudinally arranged non-striped
muscular fibres. This is the muscularis mucosae
(lamina muscularis mucosae) . At the commencement
it is absent, or only represented by a few scattered
bundles; lower down it forms a considerable stratum.
Vessels of the Oesophagus. — The larger vessels are in the submucosa and send
branches to the mucosa and muscularis. The arteries supplying the oesophagus
are derived from the inferior thyroid branch of the thyroid axis of the subclavian,
from the descending thoracic aorta and the bronchial arteries, and from the gastric
branch of the coeliac axis, and from the left inferior phrenic of the abdominal aorta.
They have for the most part a longitudinal direction. The veins are gathered into
a plexus on the outer surface of the oesophagus. This plexus receives the venous
blood from the walls of the tube. From the lower portion of the plexus branches
go to the coronary vein of the stomach. Higher up branches go to the azygos veins
FIG. 842. — Accessory muscular
fibres between the oesophagus and
pleura, and oesophagus and trachea.
(From a preparation in the Museum
of the Royal College of Surgeons of
England.)
1240 THE ORGANS OF DIGESTION
and thyroid veins. In this manner a communication is opened between the portal
veins and the systemic veins.
Lymphatics of the Oesophagus. — The lymphatics drain into the inferior deep
cervical glands and the glands of the posterior mediastinum.
Nerves of the Oesophagus. — The nerves are derived from the vagus and from
the sympathetic; they form a plexus in which are groups of ganglion-cells between
the two layers of the muscular coats. From this fibres pass to supply the muscle,
and others go to the submucous tissue to form a secondary plexus. It is usual
to regard the plexus as consisting of two parts, a ventral or anterior oesophageal
plexus, derived from the left vagus, and a dorsal or posterior oesophageal plexus,
derived from the right vagus. These two plexuses are in the posterior medias-
tinum; they communicate with each other and contain sympathetic fibres.
Movements and Innervation of the Oesophagus.
Movements. — When liquid is swallowed it is, as pointed out by Kronecker and Meltzer,
suddenly forced into the gullet by the contraction of the Mylo-hyoid muscle, the tube playing
a practically passive part.1 In the passage of solid and semisolid food the oesophagus con-
tracts. It does not contract, as was once thought, in sections, but there is a peristaltic wave.
"The wave at a given point lasts in the neck region, about 3.5 seconds, and from five
to nine seconds in the thoracic region.2 The lower end of the oesophagus or cardia has a
sphincter, the cardiac sphincter. It is usually taught that this sphincter is tonically contracted.
When a mouthful of food is swallowed it rests above the sphincter for a moment and is then
forced through by muscular contractions (Kronecker and Meltzer). If several acts of swallow-
ing follow each other rapidly the sphincter relaxes so that there is no resistance to the passage
of food. In cats Dr. Walter B. Cannon3 has demonstrated "rhythmical relaxations of the
cardia, so that fluid food streams from the stomach into the oesophagus even above the level
of the heart, then is pressed into the stomach again by a peristaltic wave, only to be released
a moment later to pour into the oesophagus anew."
Innervation. — There is in the oesophagus a local reflex, but peristalsis is dominated by the
central nerve system. "It seems probable that the peristaltic contractions of the oesophagus,
to be efficient, must be supported by nervous influences from outside. In this respect the
oesophagus is different from the remainder of the alimentary canal."4
Surgical Anatomy. — The relations of the oesophagus are of considerable practical interest
to the surgeon, as he is frequently required, in cases of stricture of this tube, to dilate the canal
by a bougie, when it is of importance that the direction of the oesophagus and its relations
to surrounding parts should be remembered. In cases of malignant disease of the oesophagus,
where its tissues have become softened from infiltration of the morbid deposit, the greatest
care is requisite in directing the bougie through the strictured part, as a false passage may easily
be made, and the instrument may pass into the mediastinum, or into one or the other pleural
cavity, or even into the pericardium.
The student should also remember that obstruction of the oesophagus, and consequent
symptoms of stricture, are occasionally produced by aneurism of some part of the aorta press-
ing upon the tube. In such a case the passage of a bougie could only hasten the fatal issue.
In passing a bougie the left forefinger should be introduced into the mouth and the epiglottis
felt for, care being taken not to throw the head too far backward. The bougie is then to be
passed beyond the finger until it touches the posterior wall of the pharynx. The patient is
now asked to swallow, and at the moment of swallowing the bougie is passed gently down-
ward, all violence being carefully avoided.
It occasionally happens that a foreign body becomes impacted in the oesophagus and can
neither be brought upward nor moved downward. When all ordinary means for its removal
have failed, and the body is lodged above the lower one-third of the gullet, external oesopha-
gotomy is performed. If the foreign body is lodged in the lower one-third of the gullet the
stomach is opened (gaslrotomy) and the foreign body is extracted. If the foreign body is
allowed to remain lodged in the oesophagus, extensive inflammation and ulceration may
ensue. In one case the foreign body ultimately penetrated the intervertebral substance, and
destroyed life t>y inflammation of the membranes and substance of the cord.
The operation of oesophagotomy is thus performed: The patient being placed upon his
back, with the head and shoulders slightly elevated, an incision, about four inches in length,
1 Recent Advances in the Knowledge of the Movements and Innervation of the Alimentary Canal. By Walter
B. Cannon, M.D., in Medical News, May 20, 1905.
2 Ibid. 3 Ibid. « Ibid.
THE ABDOMEN 1241
should be made on the left side of the trachea, from the thyroid cartilage downward, dividing
the skin, Platysma, and deep fascia. The edges of the wound being separated, the Omo-hyoid
muscle should, if necessary, be divided, and the fibres of the Sterno-hyoid and Sterno-thyroid
muscles drawn inward; the sheath of the carotid vessels, being exposed, must be drawn out-
ward, and retained in that position by retractors: the oesophagus will now be exposed, and
should be divided over the foreign body, which can then be removed. Great care is necessary
to avoid wounding the thyroid vessels, the thyroid gland, and the laryngeal nerves.
The oesophagus may be obstructed not only by foreign bodies, but also by changes in its
coats, producing stricture, or by pressure on it from without of new-growths or aneurism, etc.
The different forms of stricture are: (1) the spasmodic, occurring in neurotic individuals, and
intermittent in character, so that the dysphagia is not constant. Spasmodic stricture of the
oesophagus sometimes occurs in cases of cancer of the stomach and cancer of the liver;
(2) fibrous, due to cicatrization after injuries, such as swallowing corrosive fluids or boiling
water; and (3) malignant, usually epitheliomatous, in its nature. Cancer is most common
either at the upper end of the tube, opposite to the cricoid cartilage, or at its lower end at the
cardiac orifice. Cicatricial stricture may be treated by gradual dilatation. If a stricture is
impassible from above, the stomach may be opened, an instrument passed from below, and a
string used to divide the stricture.
The operation of oesophagostomy has occasionally been performed in cases where the stric-
ture in the oesophagus is at the upper part, with a view to making a permanent opening below
the stricture through which to feed the patient, but the operation has been far from a suc-
cessful one, and the risk of setting up diffuse inflammation in the loose planes of connective
tissue deep in the neck is so great that it wrould appear to be better, if any operative interference
is undertaken, with the idea of forming a mouth to introduce food, to perform gastrostomy.
The operation of oesophagostomy is performed in the same manner as oesophagotomy, but the
edges of the opening in the oesophagus are stitched to the skin incision. Gastrostomy is
the only operation to be thought of in malignant stricture.
THE ABDOMEN.
The abdomen (from abdo, I put away or hide, or possibly from adeps, fat) is
the largest cavity in the body. It is of an oval form, the extremities of the oval
being directed upward and downward; the upper one being formed by the under
surface of the Diaphragm, the lower by the upper concave surface of the Levator
ani muscles. In order to facilitate description, it is artificially divided into two
parts: an upper and larger part, the abdomen proper; and a lower and smaller
part, the pelvis. These two cavities are not separated from each other, but the
limit between them is marked by the brim of the true pelvis. The space is wider
above than below, and measures more in the vertical than in the transverse
diameter.
The abdomen proper differs from the other great cavities of the body in being
bounded for the most part by muscles and fasciae, so that it can vary in capacity
and shape according to the condition of the viscera which it contains; but, in
addition to this, the abdomen varies in form and extent with age and sex (Fig.
844). In the adult male, with moderate distention of the viscera, it is oval or
barrel-shaped, but at the same time flattened from before backward. In the adult
female, with a fully developed pelvis, it is conical with the apex above, and in
young children it is conical with the apex below.
Boundaries. — The boundary between the thorax and abdomen is the Dia-
phragm. This muscle forms a dome over the abdomen, and the cavity extends
high into the bony thorax, reaching to the level of the junction of the fourth costal
cartilages with the sternum. The lower end of the abdomen is limited by the
structures which clothe the inner surface of the bony pelvis, principally the Leva-
tores ani and Coccygei muscles on either side. These muscles are sometimes
termed the Diaphragm of the pelvis. The abdomen proper is bounded in front and
at the sides by the lower ribs, the abdominal muscles, and the venter ilii; behind,
by the vertebral column and the Psoas and Quadratus lumborum muscles; above,
by the Diaphragm; below, by the brim of the pelvis. The muscles forming the
1242
THE ORGANS OF DIGESTION
boundaries of the cavity are lined upon their inner surface by a layer of fascia,
differently named, according to the part which it covers.
FIG. 843.; — Topography of thoracic and abdominal viscera.
THE ABDOMEN
1243
The abdomen contains (Fig. 843) the greater part of the alimentary canal;
some of the accessory organs to digestion — viz., the liver and pancreas, the spleen,
the kidneys, and suprarenal capsules. Most of these structures, as well as the
wall of the cavity in which they are contained, are covered by an extensive and
complicated serous membrane, the peritoneum (Fig. 856).
The Apertures in the Walls of the Abdomen. — The apertures found in the walls of
the abdomen, for the transmission of structures to or from it, are the umbilicus, for
the transmission (in the foetus) of the umbilical vessels; the caval opening in the
Diaphragm, for the transmission of the postcava; the aortic opening, for the
passage of the aorta, vena azygos major, and thoracic duct; and the oesophageal
opening, for the oesophagus and vagus nerves. Below, there are two apertures
on each side: one for the passage of the femoral vessels, and the other for the
transmission of the 'spermatic cord in the male, and the round ligament in the
female.
Male Type
Infantile Type
FIG. 844. — Schematic outlines of the abdomen.
Regions (Fig. 846). — For convenience of description of the viscera, as well as
of reference to the morbid conditions of the contained parts, the abdomen is arti-
ficially divided into nine regions. Thus, if two circular lines are drawn around
the body, the one through the extremities of the ninth ribs where they join their
costal cartilages, and the other through the highest points of the crests of the ilia,
the abdominal cavity is divided into three zones — an upper, a middle, and a
lower. If two parallel lines are drawn perpendicularly upward from the centre of
Poupart's ligament, each of these zones is subdivided into three parts — a middle
and two lateral.1
The middle region of the upper zone is called the epigastric (Im, over; faar^p^
the stomach); and the two lateral regions, the right and left hypochondriac (bno,
under; yovdpot, the cartilages}. The central region of the middle zone is the
mesogastric or umbilical; and the two lateral regions, the right and left lumbar. The
middle region of the lower zone is the hypogastric or pubic region; and the lateral
regions are the right and left inguinal or iliac. The viscera contained in these
different regions are the following (Fig. 846) :
1 Anatomists are far from agreed as to the best method of subdividing the abdominal cavity. Cunningham
suggests that the lower line should encircle the body on a level with the highest point of the iliac crest, as seen
from the front — a point corresponding with a prominent tubercle on the outer lip of the iliac crest about two
inches behind the anterior superior spine. Addison (Journal of Anatonr" and Physiology, vols. xxxiv. and
xxxv.), in a careful analysis of the abdominal viscera in forty subjects, adopts the following lines: (1) a
median, from the symphysis pubis to the ensiform cartilage; (2) two lateral lines drawn vertically through a point
midway between the anterior superior iliac spine and the symphysis pubis ; (3) an upper transverse line half-way
between the symphysis pubis and the suprasternal notch; and (4) a lower transverse line midway between the
last and the upper border of the symphysis pubis. — ED. of 15th English edition.
Joessel draws a line through the cartilaginous ends of the tenth ribs: a line through the two anterior superior
spines of the ilia. On each side he carries a perpendicular line from the iliopectineal eminence to the hori-
zontal line connecting the tenth ribs. By this plan the highest plane is subcostal.
1244
THE ORGANS OF DIGESTION
Right Hypochondriac.
The greater part of the
right lobe of the liver,
the hepatic flexure of the
colon, and part of the
right kidney.
Right Lumbar.
Ascending colon, part
of the right kidney, and
some convolutions of the
small intestines.
Right Inguinal or Iliac.
The caecum and ver-
miform appendix and a
portion of the ascending
colon.
Epigastric Region.
The greater part of the
stomach, including both
cardiac and pyloric ori-
fices, the left lobe and
part of the right lobe of
the liver and the gall-
bladder, the pancreas, the
duodenum, the supra-
renal capsules, and parts
of the kidneys.
Umbilical Region.
The transverse colon,
part of the great omentum
and mesentery, transverse
part of the duodenum,
and some convolutions of
the jejunum and ileum,
and part of both kidneys.
Hypogastric Region.
Convolutions of the
small intestines, the blad-
der in children, and in
adults if distended, and
the uterus during preg-
nancy.
Left Hypochondriac.
The fundus of the
stomach, the spleen, the
extremity of the pancreas,
the splenic flexure of the
colon, and part of the
left kidney.
Left Lumbar.
Descending colon, part
of the omentum, part of
the left kidney, and some
convolutions of the small
intestines.
Left Inguinal or Iliac.
Sigmoid flexure of the
colon and a portion of
the descending colon.
The regions of the abdomen as described in the new nomenclature are shown
in Fig 845.
If the anterior abdominal wall is reflected in the form of four triangular flaps
by means of vertical and transverse incisions — the former from the ensiform car-
tilage to the symphysis pubis, the latter from flank to flank at the level of the
umbilicus — the abdominal or peritoneal cavity is freely opened into and the
contained viscera are in part exposed.1
Above and to the right side is the liver, situated chiefly under the shelter of
the right ribs and their cartilages, but extending across the middle line, and reach-
ing for some distance below the level of the ensiform cartilage. Below and to the
left of the liver is the stomach, from the lower border of which an apron-like fold
of peritoneum, the great omentum, descends for a varying distance, and obscures,
to a greater or lesser extent, the other viscera (Fig. 874) . Below it, however, some
of the coils of the small intestine can generally be seen, while in the right and left
iliac regions respectively the caecum and the sigmoid flexure of the colon are exposed.
The bladder occupies the anterior part of the pelvis, and, if distended, will project
above the symphysis pubis; the rectum lies in. the concavity of the sacrum, but
is usually obscured by the coils of the small intestine.
If the stomach is followed from left to right it will be found to be continuous
with the first part of the small intestine, or duodenum, the point of continuity being
marked by a thickened ring which indicates the position of the pyloric valve.
' It must be borne in mind that, although the term abdominal cavity is used, there is, under normal con-
ditions, only a potential cavity or lymph-space, since the viscera are everywhere in contact with the parietes. —
ED. of 15th English edition.
'«•
. LEW.S EMERSON
THE ABDOMEN
1245
The duodenum passes toward the under surface of the liver, and then, curving
downward, is lost to sight. If, however, the great omentum be thrown upward
over the chest, the terminal part of the duodenum will be observed passing across
the spine toward the left side, where it becomes continuous with the coils of the
small intestine. These measure some twenty feet in length, and if followed down-
ward will be seen to end in the right iliac fossa by opening into the caecum, the
commencement of the large intestine. From the caecum the large intestine takes
an arched course, passing at first upward on the right side, then across the middle
line and downward on the left side, and forming respectively the ascending, trans-
verse, and descending parts of the colon. In the left iliac region it makes still
another bend, the sigmoid flexure, and then follows the curve of the sacrum as
far as the rectum.
REGIO INGUINALIS
FIG. 845. — Regions of the abdomen as described in the new nomenclature.
The spleen lies behind the stomach in the left hypochondriac region, and may
be in part exposed by pulling the stomach over toward the right side.
The glistening appearance of the deep surface of the abdominal wall and of
the exposed viscera is due to the fact that the former is lined and the latter more
or less completely covered by a serous membrane, the peritoneum.
Development of the Alimentary Canal, Viscera and Peritoneum. — When
the paraxial mesoblast of the embryo has developed a series of transverse seg-
mentations it becomes converted into a row of dark, square segments known as
the protovertebrae or the mesoblastic somites, which are separated by clear, trans-
verse intervals. They appear first in the region that is to become the neck, and
from there extend back along the entire length of the trunk. These bodies are
not solely the representatives of the future permanent vertebrae, but differentiate
partly into muscles and true skin.
On each side of the protovertebrae the lateral mesoblast splits into two layers.
The upper layer is applied to the epiblast, and forms with it the somatopleure or
body- wall. The lower layer becomes adherent to the hypoblast, and forms the
splanchnopleure or wall of the alimentary canal. The space between these two
1246
THE ORGANS OF DIGESTION
layers is the caelum or the pleuroperitoneal cavity. This body-cavity is of large
size in the early stages of the development of the embryo.
Anteriorly — or, if the body is in the erect posture, superiorly — there is developed
a comparatively large space called the pericaxdiothoracic cavity; and a transverse
fold develops, which marks off this cavity from the future abdominal cavity. This
fold, with many veins of large size, develops into the primary Diaphragm, although
its dorsal part remains incomplete. The dorsal part is completed at a later period,
constituting the Diaphragm as we see it in the adult. As Dr. Frederick J. Brock-
way expresses it : "The Diaphragm is thus made up of a ventral, younger part, and
a dorsal, older part. When this posterior part fails to develop, there is opportunity
for a congenital diaphragmatic hernia to be present."
The pericardiothoracic cavity becomes divided into three cavities, and the two
lateral ones are for a time continuous with the abdominal cavity. This continuation
is, however, but temporary, and they are afterward separated. In this manner,
four large serous sacs are formed. The two lateral thoracic sacs are known as
Limit
FIG. 846. — The regions of the abdomen and their contents. Edge of costal cartilages in dotted outline.
the pleural sacs, and are lined with the pleura; the median thoracic sac is the
pericardial sac, and is lined with the pericardium ; and the abdominal sac forms the
abdominal cavity, and is lined with the peritoneum.
The primitive alimentary canal, which was formed early by the closure within
the embryo of a portion of the blastodermic vesicle, consists of three parts: first,
the fore-gut, within the cephalic flexure, dorsal to the heart; second, the mid-gut,
opening freely into the yolk-sac; and third, the hind-gut, within the caudal flexure.
In the fore-gut are developed the back portion of the mouth, the tongue, the
pharynx, the oesophagus, the stomach, the larger part of the duodenum, and the
THE ABDOMEN
1247
organs that have grown out from these structures. The hind-gut forms a portion
of the colon and the rectum, with the exception of the latter's anal end ; and the
mid-gut gives rise to the remainder of the digestive tube.
Development of the Alimentary Canal. — The fore-gut and hind-gut end
blindly, there being at first neither mouth nor anus (Figs. 847 and 848). The upper
ky
FIG. 847. — Diagrammatic outline of a longitudinal vertical section of the chick on the fourth day: ep, epi-
blast; am, somatic mesoblast; hy, hypoblast; vm, visceral mesoblast; af, cephalic fold; pf, caudal fold; am,
cavity of true amnion; ys, yolk-sac; i, intestine; s, fore-gut; a, future anus, still closed; TO, the mouth; we, the
mesentery; al, the allantoic vesicle; pp, space between inner and outer folds of amnion. (From Quain's Anat-
omy, Allen Thomson.)
part of the fore-gut becomes dilated to form the pharynx, in relation to which the
branchial arches are developed (Fig. 850); the succeeding part remains tubular,
and with the descent of the stomach is elongated to form the oesophagus. Soon
a fusiform dilatation, the future stomach, makes its appearance, and beyond this
the mid-gut opens freely into the yolk-sac (Figs. 850 and 851).
This opening is at first wide, but, as the body-walls close in around the umbilicus,
it is gradually narrowed into a tubular stalk, the yolk-stalk or vitello-intestinal duct.
Amnion
-Alluntois
Hind-gut
Fore-gut / Heart
Chorda Dorsalis
FIG. 848. — Diagram of a longitudinal section of a mammalian embryo. Very early. (After Quain.)
At this stage, therefore the alimentary canal forms a nearly straight tube in front
of the notochord and primitive aorta (Fig. 848). From the stomach to the rectum
it is attached to the notochord bv a band of mesoblast, from which the common
1248
THE ORGANS OF DIGESTION
T,
mesentery of the gut is subsequently developed. The stomach undergoes a further
dilatation, and its two curvatures can be recognized (Figs. 852 and 855), the
greater directed toward the verte-
bral column and the lesser toward
the anterior wall of the abdomen,
wThile of its two surfaces one looks
to the right and the other to the left.
The mid-gut also undergoes great
elongation, and forms a V-shaped
loop which projects downward and
forward ; from the bend or angle of
the loop the vitello-intestinal duct
passes to the umbilicus (Fig. 855).
For a time a part of the loop ex-
tends beyond the abdominal cavity
into the umbilical cord, but by
the end of the third month this
is withdrawn. With the length-
ening of the tube, the mesoblast,
which attaches it to the future ver-
tebral column and which carries the
FIG. 849. — Early form of the alimentary canal. In A a
front view and in B an antero-posterior section are repre-
sented, a. Four pharyngeal or visceral plates. 6. The
pharynx, c, c. The commencing lungs. d. The stomach.
/ / The diverticula connected with the formation of the • i i i » .1 iJ!iU
liver g The yolk-sac into which the middle intestinal groove blOOd-VCSSelS tor the Supply OI ttie
afPteerBischTohrTe)posteriorparto ""' gut, is thinned and drawn out to
form the primitive or common me-
sentery. The portion of this mesentery which is attached to the greater curva-
ture of the stomach is named the mesogastrium, and the parts which suspend
Midbrain.
Cerebellum.- ~,
Pharyngeal septum.—
Pharynx.-
Auditory pitr
Aortic bulb.-
Stomach.--\ J
•Optic vesicle.
Stomodseum.
Ventricle.
Cloacal dilatation-
of hind-gut.
Allantoic stalk."
Umbilical vein •:.
..Liver.
^.Mid-gut and yolk
stalk.
^Hind-gut.
FIG. 850. — Human embryo, about fifteen days old. Brain and heart represented from right side;
alimentary canal and yolk-sac in mesial section. (After His.)
the colon and rectum are respectively termed the mesocolon and mesorectum
(Fig. 855). About the sixth week a lateral diverticulum makes its appear-
ance a short distance beyond the vitello-intestinal duct, and indicates the future
THE ABDOMEN
1249
caecum or boundary between the small and the large intestine. This caecal divertic-
ulum has at first a uniform calibre, but its blind extremity remains rudimentary
and forms the vermiform appendix (Figs. 855 and 856). Changes also take place
Rathke's pouch
Notochord, (pituitary involution).
Lung diver-,
ticulum.
Stomach.
Liver. -I —
Opening into,
yolk sac.
AQantoie.-r—
- .\-Blind portion of
hind-gut. '
'-Wolffian duct.
A
Lung diverticulum
(Esophagus. ^
Median rudiment of
I thyroid gland.
,Mandibular arch.
Rathke's
pouch
(pituitary
involution).
Allantois. - -\
Blind portion of
hind-gut.
_/ -Wolffian duct.
FIG. 851. — Sketches in profile of two stages in the development of the human alimentary canal
Fig. A X 30. Fig. B X 20. (His.)
in the position and direction of the stomach. It falls over on its right sur-
face, which henceforth is directed backward, while its original left surface looks
79
1250
THE ORGANS OF DIGESTION
forward ; further, its greater curvature is drawn downward and to the left, away
from the vertebral column, while its lesser curvature is directed .upward, and the
commencement of ^he duodenum is pushed over to the right side of the middle
line. The mesogastrium, being attached to the greater curvature, must necessarily
follow its movements, and hence it becomes greatly elongated and drawn outward
from the vertebral column, and, like the stomach, what was originally its right
surface is now directed backward and its left forward. In this way a pouch, the
bursa omentalis, is formed behind the stomach; this pouch is the future lesser sac
of the peritoneum, and it increases in size as the alimentary tube undergoes further
development; the entrance to the pouch constitutes the future foramen of Winslow
(Figs. 852, 856, and 859). The remainder of the mid-gut becomes greatly
increased in length, so that the tube is coiled on itself, and this increase in length
demands a corresponding increase in the width of the intestinal attachment of
the mesentery, so that it becomes plaited or folded.
At this stage the small and the large intestines are attached to the vertebral
column by a common mesentery, the coils of the small intestine falling to the right
of the middle line, while the large intestine lies on the left side.1
Trachea.-
(Esophagus.-
Stomach.-
-Lung.
-Trachea.
-Pancreas.
Bile duct..
V-shaped loop_
of mid-gut.
Vitello-intestinal dnct-
Cloaca.-
Bile duct.
Pancreas.
Lung.
(Esophagus.
Stomach.
Csecum.
Cloaca.
FIG. 852. — Front view of two successive stages in the development of the alimentary canal. (His.)
The gut now becomes rotated upon itself, so that the large intestine is carried
over in front of the small intestine, and the caecum is placed immediately below
the liver; about the sixth month the caecum descends into the right iliac fossa,
and the large intestine now forms an arch consisting of the ascending, transverse,
and descending portions of the colon — the transverse portion crossing in front
of the duodenum and lying just below the greater curvature of the stomach;
within this arch the coils of the small intestine are disposed (Fig. 856). Some-
times the downward progress of the caecum is arrested, so that in the adult it
may be found lying immediately below the liver instead of in the right iliac region.
Further changes take place in the bursa omentalis and in the common mesen-
tery, and give rise to the peritoneal relations seen in the adult. The bursa omen-
talis, which at first reaches only as far as the greater curvature of the stomach,
1 Sometimes this condition persists throughout life, and it is then found that the duodenum does not cross
from the right to the left side of the vertebral C9lumn, but lies entirefy on the right side of the mesial plane,
where it is continued into the jejunum; the arteries to the small intestine (rami intestini tenuis) also arise from,
the right instead of the left side of the superior mesenteric artery.
THE ABDOMEN
1251
grows downward to form the great omentum, and this downward extension lies
in front of the transverse colon and the coils of the small intestine. The anterior
layer of the transverse mesocolon is at first quite
distinct from the posterior wall of the bursa
omentalis, but ultimately the two blend, and
hence the great omentum appears as if attached ,;,,, > g^ \ Right
to the transverse colon (Figs. 859, 860, and 861).
The mesentery of the duodenum, in which the
_ rarenal
capsule
Liver
ififfht
suprarenal
capsule
Left
suprarenal
capsule
FIG. 853. — Schematic and enlarged cross-section through
the body of a human embryo in the region of the mesogas-
trium. Beginning of third month. (Toldt.)
Anterior part of mesogastrium.
Liver
FIG. 854. — Same section as in Fig. 853, at end
of third month. (Toldt.)
Aorta.
Spleen.
Mesogastrium.
Codiac axis.
Pancreas.
Superior mesenteric
artery.
Mesentery.
Inferior mesenteric artery.
Hind-gut.
rio. 855. — Abdominal part of alimentary canal and its attachment to the primitive or common mesentery.
Human embryo of six weeks. (After Toldt.) (From Kollmann's Lntwickelungsgeschichte.)
rudiment of the pancreas is enclosed, disappears, and so this part of the gut
becomes fixed to the posterior abdominal wall, and the pancreas lies entirely
behind the peritoneal membrane. The mesenteries of the ascending and descend-
1252
THE ORGANS OF DIGESTION
ing parts of the colon disappear in the majority of cases, while that of the small
intestine assumes the oblique attachment characteristic of its adult condition.
The small omentum is formed by a thinning of the mesoblast or anterior primitive
mesentery, which attaches the lesser curvature of the stomach to the anterior
abdominal wall. By the subsequent growth of the liver this leaf of mesobiast is
Duodenum.
Mesentery.
Small
intestine.
Yolk-stalk.
Rectum.
Duodenum.
Mesocolon. ~\ 1
Caecum.
Vermiform
appendix.
Mesentery.
Yolk-stalk.
Greater
curvature
of stomach.
.Great omen-
tum.
Point where
• intestinal
loops cross
each other.
•Mesocolon.
Large intes~
tine.
•Small intes-
tine.
Rectum.
i
FIG. 856. — Illustrating two stages in the development of the human alimentary canal and its mesentery.
The arrow indicates the entrance to the bursa omentalis. (Hertwig.)
divided into two parts — viz., the small omentum between the stomach and liver,
and the falciform ligament between the liver and the abdominal wall and Dia-
phragm (Fig. 858).
The anus is developed as a slight invagination of the epiblast a short distance
in front of the posterior end of the hind-gut. This invagination is termed the
Septum transversum.
Liver.
Mesogastrium
(anterior part)
Umbilical vein.
Umbilical cord.
Aorta.
Mesogastrium
(posterior part).
Stomach.
Intestinal
V-shaped loop.
If- Mesentery.
-Colon.
FIG. 858. — The primitive mesentery of a six weeks' human embryo,
half schematic. (Kollmann.)
proctodaeum, the mesoblast between it and the hypo-
blastic lining of the hind-gut is thinned, and ultimately
the septum breaks down and disappears, and the hind-
gut opens on the surface; into this part of the hind-
gut the urinary and generative organs open for a time,
and so constitutes a common cloaca. The small portion
of the hind-gut behind the orifice of the anus is named
the caudal or post-anal gut; it communicates writh the
neural tube by means of a canal, the neurenteric canal,
already referred to. Ultimately the post-anal gut becomes obliterated, and itv
together with the neurenteric canal, finally disappears.
FIG. 857. — Final disposition
of the intestines and their vas-
cular relations: A, aorta; H,
hepatic artery; S, splenic artery;
M, Col, branches of superior
mesenteric artery; m, m',
branches of inferior mesenteric
artery. (Jonnesco.)
THE ABDOMEN
1253
The peritoneal cavity is the space left between the visceral and parietal layers of
the mesoblast, and the serous membrane is developed from these layers.
The tongue originates from the floor of the pharynx. The anterior or papillary
portion first appears as a rounded elevation, the tuberculum impar, between the
ventral ends of the mandibular and hyoid arches (Fig. 862). Between the third
and fourth arches a second larger elevation arises, in the centre of which is a
median groove or furrow. This second elevation is termed the furcula, and from
it the epiglottis is developed, while the median furrow becomes the entrance to the
larynx (Fig. 863). The tuberculum impar and the furcula are at first in apposi-
tion, but are soon separated by a ridge produced by the forward growth of the
second and third arches. This ridge gives rise to the posterior part of the tongue
and extends forward in the form of a V, so as to embrace between its two limbs
the tuberculum impar. At the apex of the V there is a pit-like invagination to
form the middle thyroid rudiment, and this depression persists as the foramen
caecum of the adult. The union of the two parts of the tongue is indicated even
in the adult by a V-shaped depression, the apex of which is at the foramen caecum,
while the two limbs run outward and forward parallel to but a little behind the
circumvallate papillae, which are therefore developed from the tuberculum impar
(Figs. 862, 863, and 864). The tonsils are developed from the second branchial
cleft, and make their appearance between the fourth and fifth months.
The liver arises in the form of two diverticula or hollow outgrowths from the
ventral surface of that portion of the fore-gut which afterward becomes the
Mesogastrium
anierius.
Liver.
Umbilical vein.
Border of the anterior
mesogastrium.
Stomach
ursa omentalis.
Pancreas.
Mesogastrium
posterius.
Duodenum.
Great amentum.
Transverse
mesocolon.
Transverse colon.
Fio. 859. — Schematic figure of the bursa omentalw. etc. Human embryo of eight weeks. (Kollmann.)
duodenum (Figs. 850 and 851). The outgrowths, which represent the right and
the left lobes, respectively, of the adult liver, give off solid buds of cells, which grow
into columns or cylinders; these unite with one another in every direction to form
a close network, in the meshes of which are contained the capillary blood-vessels.
Some of these columns become hollowed out and form the bile-clucts, while the
remainder constitute the secreting structure. The minute ducts thus produced
unite to form the right and left hepatic ducts; while the common bile-duct is devel-
oped as a protrusion from the duodenal wall, and as it grows the liver becomes
shifted away from the duodenum. The gall-bladder and cystic duct are formed by
1254
THE ORGANS OF DIGESTION
a hollow evagination from the wall of the common bile-duct. About the third
month the liver almost fills the abdominal cavity. From this period the relative
Stomach
Greater curvature
Anterior lamella of greater amentum
Posterior lamella of greater amentum
Transverse colon
Greater amentum
Diaphragm
Liver
Lesser amentum
Pancreas
Transverse mesocolon
Duodenum
Mesentery
Small intestine
FIG. 860. — Illustrating the development of the bursa omentalis, cavity of the great omentum or lesser sac.
Foetal stage. * Lesser sac. (Hertwig.)
Diaphragm
Liver
Stomach
Greater curvatun
Posterior lamella of greater omentum
Transverse coloii
Greater omentum
Leaser omentum
Pancreas
Part of omentum enclosing pancreas
Transverse mesocolon
Duodenum
Mesentery
Small intestine
FIG. 861. — Development of bursa omentalis. Infantile stage. Great omentum covers the intestines and has
fused with the transverse mesocolon. Pancreas is free from peritoneum posteriorly. (Hertwig.)
development of the liver is less active, more especially that of the left lobe, which
now becomes smaller than the right; but up to the end of foetal life the liver
remains relatively larger than in the adult.
Mandibular arch.
Hyoid arch.
FIG. 862. — The floor of the pharynx of a human embryo about fifteen days old. X 50. (From His.)
The pancreas is also an early formation, being far advanced in the second
month. It originates as a hollow projection from the hypoblast of the dorsal wall
of the duodenum (Figs. 851 and 852), opposite the hepatic diverticula, which, as
we have already seen, spring from its ventral wall. This hollow process grows
between the two layers of the dorsal mesentery and sends out offshoots, which
THE PERITONEUM
1255
branch abundantly and form a complicated tubular gland. As torsion of the
stomach takes place, the pancreas assumes a transverse position and becomes fixed
across the dorsal wall of the abdomen, the posterior layer of its mesentery under-
going absorption. Its duct ultimately opens into the duodenum together with the
common bile-duct.
The spleen, on the other hand, is of mesoblastic origin, for there is never any
connection between the intestinal cavity and the substance of this organ. It
originates in the mesenteric fold which connects the stomach to the vertebral
column (mesogastrium) (Fig. 855).
Tuberculum impar Posterior part of tongue,
(papillary part of tongue).
i
Furcula.
Mandibular arch.
Hyoid arch.
Entrance to larynx
*•
Third arch.
Fourth arch.
- Lung.
FIG. 863. — The floor of the pharynx of a human embryo about twenty-three days old. X 30. (From His.)
Papillary portion of tongue.
Mandibular arch.
Hyoid arch.
Foramen csecum. Posterior part Third arch.
of tongue.
FIG. 864. — Floor of mouth of an embryo slightly older than that shown in Fig. 863. X 16. (From His.)
THE PERITONEUM (TUNICA SEROSA).
During life and in the uncut corpse the peritoneal cavity (cavum peritonaei) is
air-tight. It is not a real cavity, as muscular tension and atmospheric pressure
permit no vacant space to form. When the surgeon or anatomist opens the
abdomen, the peritoneal cavity is at that moment produced.
The peritoneum (from nepe, about, and Tttoto, I stretch) is the largest serous
membrane in the body, and consists, in the male, of a closed sac, a part of which
is applied against the abdominal parietes, while the remainder is reflected over
the contained viscera. In the female the peritoneum is not a closed sac, since the
free extremities of the Fallopian tubes open directly into the peritoneal cavity.
The portion of the peritoneum applied against the abdominal parietes consti-
tutes the parietal peritoneum ; the portion reflected over the viscera, the visceral
peritoneum. The free surface of the membrane is smooth, covered by a layer of
flattened endothelium, and lubricated by a small cavity of serous fluid. Hence
the viscera can glide freely against the wall of the cavity or upon one another with
the least possible amount of friction. Its attached surface is rough, being con-
1256 THE ORGANS OF DIGESTION
nected to the viscera and inner surface of the parieties by means of areolar tissue
termed the subserous areolar tissue (tela subserosa). The parietal portion is loosely
connected with the fascia lining the abdomen and pelvis, but more closely to the
under surface of the Diaphragm and also in the middle line of the abdomen.
The peritoneum differs from the other serous membranes of the body in pre-
senting a much more complex arrangement — an arrangement which can only
be clearly understood by following the changes which take place in the alimentary
canal during its development; and therefore the student is advised to preface his
study of the peritoneum by reviewing the remarks on Embryology.
Structure of the Peritoneum. — It is a thin, glistening serous membrane and
consists of a connective-tissue layer and one layer of flat endothelial cells upon the
free surface of the membrane. The connective-tissue layer consists of bundles of
connective tissue which contain many connective-tissue cells and elastic fibres.
It contains a multitude of lymph-spaces, lymph-vessels, and lymph-capillaries.
Beneath the peritoneum is a layer of lax and spongy connective tissue which serves
to bind the serous membrane to parts beneath. This layer is called the subserous
connective tissue. In some regions it is plentiful; in others, as over the liver and
intestine, it is very scantily developed. The endothelial cells are flat and polyg-
onal. Some hold that they are joined together by cement-substance. Robinson
asserts that there is no cement-substance, but rather an organized connection
between the protoplasmic processes of adjacent cells.
On the surface of the endothelium between the cells numerous apertures or
interruptions are to be seen. These openings which many think are due to re-
tracted epithelium communicate with lymph-spaces beneath the epithelial layer.
The idea is held by some that the openings are permanent stomata and join
lymphatic capillaries. Some openings which are noted, the stigmata or pseudo-
stomata, are mere interruptions in the endothelial layer, and are occupied by pro-
cesses of the branched connective-tissue corpuscle of the subjacent tissue.
The amount of fluid contained in the closed sac is, in most cases, only sufficient
to 'moisten the surface, but not to furnish any appreciable quantity of free liquid.
When a small quantity can be collected, it is found to resemble lymph, and, like
that fluid, coagulates spontaneously; but when present in large quantities, as
in dropsy, it is a more watery fluid, but still contains a considerable amount of
proteid which is coagulated on boiling.
The peritoneum contains a great quantity of lymphatic structures. In the
subserous tissue the numerous lymph-spaces obtain fluid from the peritoneal
cavity. The subendothelial interstitial lymph-spaces intercommunicate and can
take up an immense quantity of fluid from the peritoneal cavity. Normally the
spaces contain both nutrient material and waste products. Lymphatics are par-
ticularly plentiful in — 1, the tendinous portion of the Diaphragm; 2, the ligamenta
lata; 3, the omentum; 4, the ventral surface of the small intestine; 5, the liver and
spleen.1
The lymph from this region reaches the mediastinal or diaphragmatic glands.
The serous surface of the Diaphragm is the region chiefly efficient in absorption
from the peritoneum, and there is a current in the peritoneal cavity directed toward
the Diaphragm.2 Absorption from the peritoneal cavity is very active. Wegner
has shown that an amount of fluid equal to from 3 to 8 per cent, of the body
weight may be absorbed in one hour. Absorption is most active from the region
of the Diaphragm and least active from the region of the pelvis. There are a
multitude of nerves in the peritoneum, and it seems probable that each endothelial
cell receives a nerve ending. The minute arteries of the peritoneum are surrounded
by nerve-plexuses. According to Robinson,3 the nerves of the peritoneum are:
1 The Peritoneum. By Byron Robinson. 2 Ibid.
THE PERITONEUM 1257
1. Myelinic. 2. Amyelinic. 3. Fibres of Remak. 4. The Vater-Pacinian
corpuscles and other varieties of nerve endings. 5. Nerve-cells. The visceral
peritoneum contains many more nerves than the parietal peritoneum.
The parietal peritoneum (peritonaeum parietale) lines the wall of the abdominal
cavity. The visceral peritoneum (peritonaeum viscerale) covers the viscera. Back
of the parietal peritoneum is a space, the retro-peritoneal space (spatium retro-
peritonaeale), which contains the great vessels and nerves, the suprarenal cap-
sules, the kidney, and ureters (Figs. 866, 867, 868, 869, and 870).
We describe the peritoneum as consisting of two sacs, a greater sac and a lesser sac
(Fig. 866). The larger part of the abdominal cavity is lined by the greater sac, as most
of the viscera are covered by it. The lesser sac is placed largely behind the stomach.
These two sacs are not two distinct cavities which communicate. They' constitute
one cavity, a portion of which has been formed into a diverticulum or recess by a
process of constriction, the result of changes produced in the position of adjacent
viscera by development. Prof. Birmingham says: "If the great sac be compared
to a bag, the lesser sac might be represented as a pocket lying behind, and open-
ing into it by a narrow orifice, the foramen of Winslow, on its posterior wall."1
The greater sac lines the walls of the abdominal cavity and covers the viscera
which are invested by peritoneum, except the posterior portion of the stomach,
the suprarenal capsule of the left side, the superior surface of the pancreas, the
Spigelian lobe and the caudate lobes of the liver, and portions of the spleen, left
kidney, and transverse colon, which are covered by peritoneum of the lesser sac.2
To trace the continuity of the membrane from one viscus to another, and from
the viscera to the parietes, it is necessary to follow its reflections in the vertical
and horizontal directions, and in doing so it matters little where a start is made.
If the stomach is drawn downward, a fold of peritoneum will be seen stretching
from its lesser curvature to the transverse fissure of the liver (Figs. 866 and 872).
This is the gastro-hepatic or lesser omentum, and consists of two layers; these, on
being traced downward, split to envelop the stomach, covering respectively its
anterior and posterior surfaces. At the greater curvature of the stomach they
again come into contact and are continued downward in front of the transverse
colon, forming the anterior two layers of the great or gastro-colic omentum (Figs.
866 and 874). Reaching the free edge of this fold they are reflected upward as
its two posterior layers, and thus the great omentum consists of four layers of
peritoneum. Followed upward the two posterior layers separate so as to enclose
the transverse colon, above which they once more come into contact and pass
backward to the abdominal wall as the transverse mesocolon (mesocolon trans-
versum) (Fig. 866). Reaching the abdominal wall about the level of the transverse
part of the duodenum, the two layers of the transverse mesocolon become separated
from each other and take different directions ; the upper or anterior layer, known
as the ascending layer of the transverse mesocolon, ascends in front of the pancreas,
and its further course will be followed presently (Fig. 866). The lower or posterior
layer is carried downward, as the anterior layer of the mesentery, by the superior
mesenteric vessels to the small intestine, around which it may be followed and
subsequently traced upward as the posterior layer of the mesentery to the abdomi-
nal wall. From the posterior abdominal wall it sweeps downward over the aorta
into the pelvis, where it invests the first part of the rectum and attaches it to the
front of the sacrum by a fold termed the mesorectum (Fig. 866). Leaving first
the sides and then the front of the second part of the rectum it is reflected on to
the back of the bladder, and, after covering the posterior and upper aspects of
this viscus, is carried by the urachus and obliterated hypogastric arteries as folds,
1 Prof. Cunningham's Text-book of Human Anatomy. * Ibid.
1258 THE ORGANS OF DIGESTION
on to the posterior surface of the anterior abdominal wall (Fig. 865). The fold
upon the urachus is the plica urachi (plica umbilicalis media) ; the fold on each
obliterated hypogastric artery is the plica hypogastrica (plica umbilicalis lateralis).
Between the rectum and bladder it forms a pouch, the recto-vesical pouch (exca-
vatio rectovesicalis) , bounded on the sides by two crescentic or semilunar folds
(plicae rectovesicales), which pass from the posterior surface of the bladder to the
sides of the rectum; the bottom of this pouch is about on a level with the middle
of the vesiculae seminales — i. e., three inches or so from the orifice of the anus.
When the bladder is distended the peritoneum is carried up with the expanded
viscus, so that a considerable part of the anterior surface of the latter lies directly
against the abdominal wall without the intervention of the peritoneal membrane.
When the bladder is empty the peritoneum forms a transverse fold over its upper
surface (plica vesicalis transversa).
In the female the peritoneum is reflected from the rectum on the upper part
of the posterior vaginal wall, forming the recto-vaginal pouch or pouch of Douglas
(excavatio rectouterina) (Fig. 866). In the pouch of Douglas are two folds of peri-
toneum (plica rectouterinae) , which begin at the posterior surface of the cervix,
extend back to the sides of the rectum, and bound above the deepest portion of the
pouch. The pouch is then carried over the posterior aspect and fundus of the uterus
on to its anterior surface, which it covers as far as the junction of the body and
cervix uteri, forming here a second but shallower depression, the utero-vesical
pouch (excavatio vesicouterina) . It is also reflected from the sides of the uterus to
the lateral wall of the pelvis on each side as an expanded fold, the broad ligament of
the uterus (ligamenum latum uteri) , in the free margin of each broad ligament can
be felt a thickened cord-like structure, the Fallopian tube (tuba uterina [Fallopii]).
When the peritoneum lining the anterior abdominal wall is examined from
behind, it is noticed that certain structures which lie in front of it form five peri-
toneal ridges (Fig. 865). The structure in the middle line is the urachus, which is
the remains of the foetal allantois. In the adult it is a fibrous cord which passes from
the umbilicus to the summit of the bladder. This cord is slender above, but broader
below. External to the urachus are the fibrous cords which resulted from oblit-
eration of the hypogastric arteries (arteriae umbilicales) . These cords become more
slender as they ascend toward the sides of the urachus and pass to the umbilicus.
More external still are the folds formed by the deep epigastric arteries. The fold
over each epigastric artery is the plica epigastrica; the fold over each obliterated
hypogastric artery is the plica hypogastrica; the fold over the obliterated urachus
is the plica urachi.
The five peritoneal ridges formed by the above-named structures create three
peritoneal fossae on each side, called the inguinal fossae or pouches (fovea inguinales).
The external inguinal fossa (fovea inguinalis lateralis) is external to the deep epi-
gastric artery and corresponds to the internal abdominal ring. There is a funnel-
shaped depression in its floor marking the point at which the inguinal process
passed down. This depression, if marked, predisposes to oblique inguinal hernia.
The middle inguinal fossa (fovea inguinalis medialis) is placed between the deep
epigastric arteries and the obliterated hypogastric vessels. The internal inguinal
fossa or the supravesical fossa (fovea supravesicalis) is between the obliterated
hypogastric artery and the urachus. Just beneath the inner termination of Pou-
part's ligament there is another fossa, the femoral or crural fossa (fovea femoralis),
which corresponds to the situation of the femoral ring. The obliterated hypo-
gastric artery is to the inner side of this fossa.
On following the parietal peritoneum upward on the back of the anterior
abdominal wall it is seen to be reflected around a fibrous band, the ligamentum
teres or obliterated umbilical vein (Figs. 868, 869, and 870), which reaches from the
THE PERITONEUM
1259
umbilicus to the under surface of the liver. Here the membrane forms a somewhat
triangular fold , the falciform or suspensory ligament of the liver (ligamentum falciforme
hepatis), which attaches the upper and anterior surfaces of that organ to the Dia-
phragm and abdominal wall. With the exception of the line of attachment of this
ligament the peritoneum covers the under surface of the anterior part of the Dia-
phragm and is reflected from it on to the upper surface of the liver as the anterior or
superior layer of the coronary ligament (ligamentum coronarium hepatis anterior).
Covering the upper and anterior surfaces of the liver it is reflected around its sharp
margin on to its under surface as far as the transverse fissure, where it is continuous
M. iliacus.
External
I inguinal
fossa.
External,
iliac
artery.
Extern
Hiuc
vein.
Internal inijtiiital
fossa.
Femoral
fossa.
Superior vesical
artery,
fiddle inguinal
/MM.
FIG. 865. — Posterior view of the anterior abdominal wall in its lower half. The peritoneum is in place,
and the various cords are shining through. (After Joessel.)
with the anterior layer of the small omentum from which a start was made (Fig. 866) .
The posterior layer of this omentum is carried backward from the transverse fissure
over the under surface and Spigelian lobe of the liver, and is then reflected, as the
posterior or inferior layer of the coronary ligament (ligamentum coronarium hepatis
posterior), on to the Diaphragm and is prolonged downward over the pancreas to
become continuous with the ascending layer of the transverse mesocolon (Fig. 866).
Between the two layers of the coronary ligament there is a triangular surface of the
liver which is devoid of peritoneum ; it is named the bare area of the liver, and is
attached to the Diaphragm by connective tissue. If, however, the two layers of the
coronary ligaments are traced toward the right and left margins of the liver, they
approach each other, and, ultimately fusing, they form the right and left lateral
ligaments of the liver and attach its right and left lobes respectively to the Dia-
phragm.
If the small omentum is followed toward the right side it is seen to form a
distinct free edge around which its anterior and posterior layers are continuous
1260 THE ORGANS OF DIGESTION
with each other and between which are situated the portal vein, hepatic artery, and
bile-duct. If the finger is introduced behind this free edge, it passes through a
somewhat constricted ring, the foramen of Winslow (foramen epiploicum [Wins-
lowi]) (Figs. 866, 868, and 871). This is the communication between what are
termed the greater and lesser sacs of the peritoneum and has the following bound-
aries: in front, the free edge of the gastro-hepatic omen turn. This free edge is
called the ligamentum hepatoduodenale. The gastro-hepatic omen turn has the
portal vein, hepatic artery, and bile-duct between its two layers (Fig. 872); behind
the foramen of Winslow is the postcava; above, are the Spigelian and caudate
lobes of the liver; below, the duodenum and the hepatic artery, as the latter passes
forward and upward from the coeliac axis.
The lesser peritoneal cavity or the lesser sac of the peritoneum (bursa omentalis)
(Figs. 866, 868, and 871), therefore, lies behind the small omen turn and has the
following dimensions: above, it is limited by the portion of the liver which lies
behind the transverse fissure; below, it extends downward into the great omen turn,
reaching, in the foetus, as far as its free edge (Fig. 860); in the adult, however, its
vertical extent is limited by adhesions between the layers of the omen turn. In front,
it is bounded by the small omentum, stomach, and anterior two layers of the great
omen turn; behind, by the two posterior layers of the great omentum, the transverse
colon, and ascending layer of the transverse mesocolon which passes upward in
front of the pancreas as far as the posterior surface of the liver. Laterally the
lesser sac reaches from the foramen of Winslow on the right side as far as the
spleen on the left (recessus lienalis) (Fig. 873), where it is limited by the lieno-renal
ligament. The extent of the lesser sac and its relations to surrounding parts can
be definitely made out by tearing through the small omentum and inserting the
hand through the opening thus made. A passage (vestibulum bursae omentalis)
leads out from the foramen of Winslow over the head of the pancreas to the left as
far as the median vascular gastro-pancreatic fold (plica gastropancreatica) (Fig. 871).
This fold carries the gastric artery and the coronary vein. From the vestibule
there is a narrow and upward prolongation behind the lesser omentum and cau-
date lobe of the liver and in front of the lumbar portion of the Diaphragm.
This prolongation is the superior omental recess (recessus omentalis superior).
The chief part of the lesser peritoneal cavity extends downward from the gastro-
pancreatic fold and is called the inferior omental recess (recessus omentalis inferior).
The constriction which separates the two recesses is due to the passage around
the lesser sac and to the front of the gastric and hepatic arteries. "The former
winds around its left side, the latter around its right, and each raises up a fold
of peritoneum which projects strongly into the sac and partially divides it into
two" (Cunningham). A small projection of the lesser sac passes to the right side
behind the beginning of the duodenum. The splenic artery in its course to the
spleen lies back of the posterior layer of the lesser sac.
It should be stated that during a considerable part of foetal life the transverse
colon is suspended from the posterior abdominal wall by a mesentery of its own—
the two posterior layers of the great omentum passing, at this stage, in front of and
above the colon (Fig. 860). This condition sometimes persists throughout adult
life, but, as a rule, adhesion occurs between the mesentery of the transverse colon
and the posterior layer of the great omentum, with the result that the colon
appears to receive its peritoneal covering by the splitting of the two posterior
layers of the latter fold.
In addition to tracing the peritoneum vertically, it is necessary to trace it hori-
zontally (Figs. 867, 868, 869, and 870). If this is done below the transverse colon,
the circle is extremely simple, as it includes only the greater sac of the peritoneum
(Fig. 867). Above the level of the transverse colon the arrangement is more com-
plicated, on account of the existence of the two sacs.
THE PERITONEUM
1261
Starting from the linea alba, below the level of the transverse colon, and tracing
the continuity in a horizontal direction to the right, the peritoneum covers the
internal surface of the abdominal wall almost as far as the anterior border of
the Quadratus lumborum muscle; it encloses the caecum, and is reflected over the
TRANSVERSE
MCSOCOLON
SMALL SAC
FORAMEN OFWINSLOW,
WITH ARROW PASSED
THROUGH IT
PANCREAS
THIRD PART OF
DUODENUM
TRANSVERSE
COLON
MESENTERY
SMALL
INTESTINE
POUCH OF
DOUGLAS
FIG. 866. — Diagrammatic mesial section of the female body, to show the peritoneum on vertical tracing. The
great sac of the peritoneum is black and is represented as being much larger than in nature; the small sac is very
darkly shaded; the peritoneum on section is shown as a whjte line, and a white arrow is passed through the fora-
men of Wiuslow from the great into the small sac. (Cunningham.)
sides and anterior surface of the ascending colon, fixing it to the abdominal wall,
from which it can be traced over the kidney to the front of the bodies of the ver-
tebrae. It then passes along the mesenteric vessels to invest the small intestine,
and back again to the spine, forming the mesentery, between the layers of which
are contained the mesenteric blood-vessels, nerves, lacteals, and glands. Lastly,
it passes over the left kidney to the sides and anterior surface of the descending
colon, and, reaching the abdominal wall, is continued along it to the middle line
of the abdomen.
Above the transverse colon (Fig. 868) the peritoneum can be traced, forming
the greater and lesser cavities, and their communication through the foramen of
Winslowcan be demonstrated. Commencing in the middle line of the abdomen,
the membrane may be traced lining its anterior wall, and sending a process back-
ward to encircle the obliterated umbilical vein (the round ligament of the liver),
forming the falciform or longitudinal ligament of the liver. Continuing its course
to the right, it is reflected over the front of the upper part of the right kid-
ney, across the postcava and aorta, and over the left kidney to the hilum of the
spleen, forming the anterior layer of the lieno-renal ligament, the posterior layer
being formed by the termination of the cul-de-sac of the greater cavity between
the kidney and spleen. From the hilum of the spleen it is reflected to the
stomach, forming the posterior layer of the gastro-splenic omentum (lig amentum
1262
THE ORGANS OF DIGESTION
gastrolienale). It covers the posterior surface of the stomach, and from its lesser
curvature it passes around the portal vein, hepatic artery, and bile-duct, and back
Small Lymphatic Ascending
Mesentery Aorta intestine node Postcava colon
j
Peritoneum
Mesocolon
(imperfect)
Psoas
Right
kidney
Left kidney
FIQ. 867. — Peritoneal reflection in transverse section of lumbar region below the transverse colon.
Seen from above. Schematic. (Tillaux.)
again to the stomach, as the lesser omentum, and thus it forms the anterior boun-
dary of the foramen of Winslow. It now covers the front of the stomach, and
Vessels in lesser
omentum
Lig. teres
Aorta
FIG. 868. — Transverse section of peritoneum above the transverse colon. The arrow points to the lesser
sac and passes through the foramen of Winslow.
upon reaching the cardiac extremity it passes to the hilum of the spleen, form-
ing the anterior layer of the gastro-splenic omentum. From the hilum of the
THE PERITONEUM
1263
spleen it can be traced over the surface of this organ, to which it gives a serous
covering; it is then reflected from the posterior border of the hilum on to the left
kidney, forming the posterior layer of the lieno-renal ligament.
Vessels in lesser
amentum
Postcava
FIG. 869. — Horizontal section through the abdomen at the level of the foramen of Winslow.
(Modified from Godlee.)
Lesser amentum, i ROUND LIGAMENT OF LIVER.
Gastro-splenic
amentum. \
Hepatic artery, portal
'vein, and hepatic duct.
LIENO-RENAL LIGAMENT. Abdominal aorta. Postcava
FIG. 870. — Transverse section of peritoneum.
Numerous folds, formed by the peritoneum, extend between the various organs or
connect them to the parietes. These serve to hold the organs in position, and at the
same time enclose the vessels and nerves proceeding to each part. Some of these
1264
THE ORGANS OF DIGESTION
folds are called ligaments, such as the ligaments of the liver and the false ligaments
of the bladder. Others, which connect certain parts of the intestine with the
abdominal wall, constitute the mesenteries; and lastly, those which proceed from
the stomach to certain viscera in its neighborhood are called omenta.
Papillary tubercle
Chit edge of peritoneum
Spleen covered
'by peritoneum
Descending
duodenum
Cut edge of peritoneum
FIG. 871. — Bursa omentalis, opened from the front by an incision through the gastro-colic omentum. A probe
passes through the foramen of Winslow and rests on the gastro-pancreatic fold. (Henle.)
The Ligaments of the Peritoneum. — The ligaments, formed by folds of the peri-
toneum, include those of the liver, spleen, bladder, and uterus. They will be
found described with their respective organs.
The Omenta. — The omenta are: the lesser omentum, the great omentum, and the
gastro-splenic omentum.
The Lesser or Gastro-hepatic Omentum (omentum minus] (Figs. 866 and 871) is the
duplicature which extends between the transverse fissure of the liver and the right
side of the abdominal portion of the oesophagus, the lesser curvature of the stomach,
and the upper portion of the superior surface of the duodenum. The portion going
to the oesophagus and stomach is called the hepato-gastric ligament (ligamentum
hepatogastricum). The division of the ligament which goes to the oesophagus is
strong and dense; the division which goes to the lesser curvature of the stomach
is thin and relaxed. The portion of the lesser omentum which goes to the
duodenum is continuous with the first-named portion. It is called the hepato-
duodenal ligament (ligamentum hepatoduodenale) . The right margin of this liga-
ment is free and concave. The hepato-colic ligament (ligamentum hepatocoli-
cum) is not invariably present. It is a fold of the hepato-duodenal ligament and
runs from the posterior surface of the gall-bladder to the descending portion of
the duodenum or possibly to the transverse colon. From the free margin of the
termination of the hepato-duodenal ligament a fold often passes to the front
of the right kidney. It is known as the duodeno-renal ligament (ligamentum
duodenorenale) . The lesser omentum is extremely thin, and consists of two layers
of peritoneum; that is, the two layers covering respectively the anterior and
THE PERITONEUM
1265
posterior surfaces of the stomach. The posterior layer is part of the wall of the
lesser peritoneal cavity; the anterior layer, of the greater peritoneal cavity. When
the two layers reach the lesser curvature of the stomach, they join together and
ascend as the double fold to the transverse fissure of the liver; to the left of this
HEPATIC
DUCT
ROUND OMENTAL
LIGAMENT TUBEROSITY GASTRIC
IMPRESSION
POSTERIOR LAYER
OF LESSER
OMENTUM
OESOPHAGUS
CYSTIC DUCT
DUODENAL
IMPRESSION
FREE EDGE
OF LESSER
OMENTUM
PORTAL
VEIN
COMMON
BILE-DUCT
PANCREATIC DUCT
PYLORUS
RIGHT GASTRO-
EPIPLOIC ARTERY
SUPERIOR PANCREATICO-
DUODENAL ARTERY
FIG. 872. — Structure between the layers of the lesser omentum. The liver has been raised up, and the
anterior layer of the omentum removed. Semidiagrammatic. (Cunningham.)
fissure the double fold is attached to the fissure of the ductus venosus as far as
the Diaphragm, where the two layers separate to embrace the end of the oesoph-
agus. At the right border the lesser .omentum is free, and the two layers of
which it is composed are continuous. The anterior layer, which belongs to the
RENAL SURFACE
POUCH OF GREATER SAC
LIENO-RENAL LIGAMENT
PHRENIC SURFACE
CASTRO-SPLENIC
OMENTUM
POUCH OF GREATER SAC
GASTRIC SURFACE
FIG. 873. — Horizontal section through the stomach, pancreas, spleen, and the left kidney to show peritoneal
reflections at the hilum of the spleen. (G. S. H.)
greater sac, turns around the hepatic vessels to become continuous with the poste-
rior layer belonging to the lesser one. They here form a free, rounded margin,
which contains between its layers the hepatic artery, the common bile-duct, the
portal vein, lymphatics, and the hepatic plexus of nerves (Fig. 872) — all these struc-
80
1266 THE ORGANS OF DIGESTION
tures being enclosed in loose areolar tissue, called Glisson's capsule. Between the
layers where they are attached to the stomach lie the gastric artery and the pyloric
branch of the hepatic artery, anastomosing with it. From the left side of the
greater curvature of the stomach a fold passes to the gastric surface of the spleen,
covers the spleen, and passes from the renal surface of the spleen around the
left kidney to the Diaphragm.1 The fold passing to the spleen is known as the
gastro-splenic ligament or the gastro-splenic omentum (Fig. 873). The portion pass-
ing to the Diaphragm is known as the spleno-phrenic ligament (ligamentum phreni-
colienale). The gastric veins or vasa brevia pass from the left side of the greater
curvature of the stomach toward the spleen in the gastro-splenic omentum.
The Great or Gastro-colic Omentum (omentum majus) (Figs. 866 and 874) is the
largest peritoneal fold. It consists of four layers of peritoneum, two of which
descend from the stomach, one from its anterior, the other from its posterior
surface, and, uniting at its lower border, descend in front of the small intestines,
sometimes as low down as the pelvis; they then turn upon themselves, and ascend
again as far as the transverse colon, where they separate and enclose that part
of the intestine. These separate layers may be easily demonstrated in the young
subject, but in the adult they are more or less inseparably blended. At the free
margins the two outer layers and the two inner layers become continuous. The
left border of the great omentum is continuous with the gastro-splenic omentum;
its right border extends as far only as the duodenum. The great omentum is
usually thin, presents a cribriform appearance, and always contains some adipose
tissue, which in fat subjects accumulates in considerable quantity. Between its
two anterior layers is the anastomosis between the right and left gastro-epiploic
arteries. In opening the abdomen the great omentum is rarely found spread out
evenly over the intestines. It often projects between intestinal coils, or is largely
gathered in some one region, or is pushed in front of the stomach by distention
of the colon.
The lower portion of the lesser sac of the peritoneum continues for a distance
between the ascending and descending layers of the great omentum (Fig. 866).
The portion of the lesser peritoneal cavity within the great omentum is more or
less obliterated in the adult by adhesion between its opposing layers. At birth
the omentum is very short and barely reaches the umbilicus. In adults its length
varies greatly. In some individuals it is very short; in others it passes into the
pelvis. Mr. Lockwood points out that in persons under forty-five years of age
the omentum can rarely be pulled down below the level of the pubic spine; it
generally can be in older persons.
The Gastro-splenic Omentum is the fold which connects the margins of the
hilum of the spleen to the cul-de-sac of the stomach, being continuous by its lower
border with the great omentum. It was described as the gastro-splenic liga-
ment (Fig. 873).
The Mesenteries. — The mesenteries are: the mesentery proper, the transverse
mesocolon, the sigmoid mesocolon, the mesorectum (p. 1269), and the mesentery of
the vermiform appendix. In addition to these there are sometimes present an
ascending and a descending mesocolon.
The Mesentery (mesenterium) (fjieaov evre^ov) (Figs. 866, 875, and 876), so called
from being connected to the middle of the cylinder of the small intestine, is the
broad fold of peritoneum which connects the convolutions of the jejunum and
ileum with the posterior wall of the abdomen. It consists of a layer of connec-
tive tissue, each side of which is covered with peritoneum. In the connective
tissue there are fatty masses. Its root (radix mesenterii) , the part connected with
the vertebral column, is narrow, about six inches in length, and directed obliquely
1 Spalteholz, Hand Atlas of Human Anatomy. Translated and edited by Prof. Lewellys F. Barker.
THE PERITONEUM
1267
from the left side of the second lumbar vertebra to the right sacro-iliac symphysis
(Fig. 876). Its intestinal border is vastly broader (measures about twenty feet);
and here its two layers separate so as to enclose the intestine, and form its peri-
toneal coat. Its breadth, between its vertebral and intestinal border, is about
eight inches. Its upper border is continuous with the under surface of the trans-
verse mesocolon; its lower border, with the peritoneum covering the caecum and
FIG. 874. — The great omentum as seen from the front. (Testut.)
ascending colon. The origin of the mesentery above is just beyond the termina-
tion of the duodenum, and it terminates below in the angle formed by the junction
of the ileum and the colon. It serves to retain the small intestines in their position,
and contains between its layers the mesenteric vessels and nerves, the lymphatic
vessels and mesenteric glands. These glands number from 50 to 150. Occa-
sionally congenital mesenteric openings exist. In stout individuals the mesentery
contains much fat. If there is much fat the mesentery is not translucent; if
there is little fat it is translucent. It may be actually transparent above and
translucent or opaque below. The thinnest part of the mesentery is above. As
we descend it becomes thicker, because of the presence of fat, fibrous ligament,
and muscular tissue.1
1 Intestinal Localization. By Geo. H. Monks, Annals of Surgery, October, 1903.
1268
THE ORGANS OF DIGESTION
In most cases the peritoneum covers only the front and sides of the ascending
and descending parts of the colon. Sometimes, however, these are surrounded by
the serous membrane and attached to the posterior abdominal wall by an ascending
mesocolon (mesocolon ascendens) and a descending mesocolon (mesocolon descendens)
Mesentery
(lejt leaf) '
Root of mesen-
tery
Jleurr
Sigmoid flexure
Cxcum
Duodenum
--•»sf
FIG. 875. — Mesentery. Small intestine pushed to the right and above. (Tillaux.)
respectively. At the place where the transverse colon turns downward to form the
descending colon, a fold of peritoneum is continued to the under surface of the
Diaphragm opposite the tenth and eleventh ribs. This is the phreno-colic ligament
(ligamentum phrenicocolicum) ; it passes below the spleen, and serves to support
this organ, and therefore it has received the second name of sustentaculum lienis.
The Transverse Mesocolon (mesocolon transversum) (Fig. 876) is a broad fold,
which connects the transverse colon to the posterior wall of the abdomen. It is
formed by the two ascending or posterior layers of the great omentum, which, after
separating to surround the transverse colon, join behind it, and are continued
backward to the spine, where they diverge in front of the duodenum. This fold
contains between its layers the vessels which supply the transverse colon.
THE PERITONEUM
1269
The Sigmoid Mesocolon (mesocolon sigmoideum) (Fig. 876) is the fold of peri-
toneum which retains the sigmoid flexure in connection with the left iliac fossa.
This portion of intestine remains always freely movable.
The Mesorectum is really only the lower portion of the sigmoid mesocolon. It
is the name formerly given to the narrow fold which, according to the old defini-
Right lateral Falciform ligt
ligament of liver. of liver.
Vena cava inferior. ?jj
(Esophagus.—
Right phrenic artery. ••
Coronary artery. ~*
Hepatic artery. —
Splenic artery....^
Pancreas.
Inf. pane. -duo. artery.
Colica media.
Superior mesenteric.
Duodenum (3rd part).
Aorta.
Duodenum (2nd part).
Right and left kidneys.
Superior mesenteric.
Aorta.
Colica sinistn
Colica dextri
Sigmoid artery.
p. hamorrhoidal artery.
Common iliac artery."
Internal iliac artery.——
External iliac artery. "
Epigastric artery. -
Bladder. ••
Peritoneum.
Extra-peritoneal tissue.
I gastro- hepatic omentun
Gaitro-phrenic ligament.
Gattro-splenic amentum.
Foramen of Winslow.
Duodenum (tat part).
Costo-colic ligament.
Dot between two anterior
layers of great omentum.
Transverse meso-colon.
Bare surface for descend-
ing colon.
The two layers of the
mesentery proper.
Bare surface for ascend-
ing colon.
Sigmoid meso-colon.
Bare surface for caecum.
Bare surface for 2nd part
. of rectum.
5 Left lateral false liga-
( ment of bladder.
.MF
FIG. 876. — Diagram devised by Dr. Del6pine to show the lines along which the peritoneum leaves the w
of the abdomen to invest the viscera.
all
tion of the rectum, connects the upper part of the rectum with the front of the
sacrum. It contains the superior hemorrhoidal vessels.
The Mesoappendix or Mesentery of the Vermiform Appendix (mesenteriolum pro-
cessus vermiformis) (Fig. 880) is a double fold of peritoneum which usually completely
surrounds the vermiform appendix. It is usually described as a triangular fold,
and at a glance it appears so, but Jonnesco points out that it has four borders: a
superior or mesenteric border; a right or caecal; a left or free, and an inferior
or appsndicular. One of the borders is often extremely short. The upper sur-
face of the mesoappendix is continuous with the lower surface of the mesentery
proper and with the left or internal fold of the peritoneum covering the caecum.
The lower surface of the mesoappendix is continuous with the right or external
1270
THE ORGANS OF DIGESTION
fold of peritoneum covering the caecum. As a rule, the entire appendix is covered
with peritoneum; sometimes a portion of the base is uncovered, and this portion of
the diverticulum is then extraperitoneal. The tip is never extraperitoneal. The
mesoappendix may be attached to the entire length of the appendix, but, as a
rule, the tip is free. In fact, one-third, one-half, or two-thirds may be free and
occasionally the mesoappendix is a mere vestige. Between the two peritoneal
layers of the mesoappendix there is connective tissue, and often fat. In the
connective tissue are the appendicular blood-vessels, lymph-vessels, and nerves.
The Appendices Epiploicae are small pouches of the peritoneum filled with fat
and situated along the colon and upper part of the rectum. They are chiefly
appended to the transverse colon.
t
INFERIOR
MCSENTCRIC
VEIN
SUPERIOR
DUODENAL
FOLD
SUPERIOR
DUODENAL
FOLD
INFERIOR
DUODENAL
FOLD
INFERIOR
DUODENAL
FOLD
ARTERIA
COLICA
SINESTRA
FIG. 877. — Superior and inferior duodenal fossa. (Poirier and Charpy.)
Retro-peritoneal Fossae. — In certain parts of the abdominal cavity there are
recesses of peritoneum forming culs-de-sac or pouches, which are of surgical inter-
est in connection with the possibility of the occurrence of retro-peritoneal hernia.
One of these, which was previously described, is the lesser sac of the peritoneum
(Figs. 866 and 868), which may be regarded as a recess of peritoneum through the
foramen of Winslow, in which a hernia may take place, but there are several
others, of smaller size, which require mention.
These recesses of fossae may be divided into three groups, viz.: (1) the duodenal
fossae; (2) pericaecal fossae; and (3) the intersigmoid fossa.
1. Duodenal Folds and Fossae. — Moynihan has described no less than nine fossae
as occurring in the neighborhood of the duodenum. Three of these are fairly
constant. Five of the fossae are here considered, (a) The inferior duodenal
fossa or fossa of Treitz (Fig. 877) is the most constant of all the peritoneal fossae
in this region, being present in from 70 to 75 per cent, of cases. It is situated
opposite the third lumbar vertebra on the left side of the ascending portion of the
duodenum. The opening into the fossa is directed upward, and is bounded by a
thin, sharp fold of peritoneum with a concave free upper margin. This fold of
peritoneum is called the inferior duodenal fold (plica duodenomesocolica) . The
tip of the index finger introduced into the fossa under the fold passes some little
distance up behind the ascending or fourth portion of the duodenum. One margin
of the fold is attached to the ascending portion of the duodenum; another margin
is attached to the parietal peritoneum. (&) The superior duodenal fossa (Fig. 877)
is the next most constant pouch or recess, being present in from 40 to 50 per cent,
of cases. It often coexists with the inferior one, and its orifice looks downward,
in the opposite direction to the preceding fossa. It lies to the left of the ascend-
THE PERITONEUM
1271
ing portion of the duodenum. It is bounded in front by the superior duodenal fold
(plica duodenojejunalis), which is triangular and has a free semilunar base; to the
RIGHT RETRO-
DUODENAL
WALL
INFERIOR
DUODENAL
ANGLE
INFERIOR
MESENTERIC
VEIN
PARIETAL FOLD
OF DUODENUM
LEFT COLIC
ARTERY
INFERIOR MESEN-
TERIC ARTERY
FIG. 878. — Retro-duodenal fossa. (Poirier and Charpy.)
right it is blended with the peritoneum covering the ascending duodenum, and to
the left with the peritoneum covering the perirenal tissues. The fossa is bounded
in front by the superior duodenal fold; behind by the second lumbar vertebra; to
the right by the duodenum. Its depth is 2 cm., and it terminates in the angle
formed by the left renal vein crossing the aorta. This fossa is of importance, as
it is in relation with the inferior mesenteric vein; that is to say, the vein almost
always corresponds to the line of union of the superior duodenal fold with the
posterior parietal peritoneum, (c) The duodeno-jejunal fossa or mesocolic fossa
(recessus duodenojejunalis} is formed where the duodeno-jejunal angle enters the
root of the transverse mesocolon. There are two forms: (1) a single fossa and (2)
a double fossa. It can be seen by pulling the jejunum downward and to the right,
after the transverse colon has been pulled upward. It will appear as an almost
circular opening, looking downward and to the right, and bounded by two free
borders or folds of peritoneum, the duodeno-mesocolic ligaments. The opening
admits the little finger into the fossa to the depth of from 2 to 3 cm. The fossa
is bounded above by the pancreas, to the right by the aorta, and to the left by the
kidney; beneath is the left renal vein. The fossa exists in from 15 to 20 per
cent, of cases, and has never yet been found in conjunction with any other form
of duodenal fossa, (d) Paraduodenal fossa or the fossa of Landzert (recessus duo-
denojejunalis) is most distinct in the infant, and is to the left of the ascending
portion of the duodenum. The fold of peritoneum to its outer side and above is
produced by the inferior mesenteric vein. Its lower limit is a fold called the
mesenterico-mesocolic fold, (e) The retroduodenal fossa (Fig. 878) was described
in 1893 by Jonnesco. It is a peritoneal cul-de-sac, sometimes found behind the
horizontal and ascending portions of the duodenum.
2. Pericaecal Folds and Fossae.— There are at least three pouches or recesses to be
found in the neighborhood of the caecum, which are termed pericaecal fossae. (1)
1272
THE ORGANS OF DIGESTION
The ileo-colic fossa or superior ileo-caecal (recessus ileocaecalis superior) (Fig. 879)
is formed by a fold of peritoneum, the ileo-colic fold, arching over a branch of
the ileo-colic artery, which supplies the ileo-colic junction, and appears to be the
direct continuation of the artery. The fossa is a narrow chink situated between
the ileo-colic fold in front, and the mesentery of the small intestine, the ileum,
ANTERIOR
ILEOOECAL
ARTCRY
ANTERIOR ILEO-
OECAL FOLD
MESENTERY
ANTERIOR
ILEOC/ECAL
FOSSA
INFERIOR
ILEOC/ECAL
FOLD
FIG. 879. — Anterior, sometimes called superior, ileo-cajcal fossa. (Poirier and Charpy.)
ILEO-APPENDICULAR
FOSSA
MESENTERY
APPENDICULAR
ARTERY
ILEO-APPENDICULAR
ARTERY
MESO-APPENDIX
FIG. 880. — Ileo-appendicular or inferior ileo-csecal fossa. The caecum and ascending colon have been
rawn outward and downward, the ileum upward and backward, and the appendix downward. (Poirier
,nd Charov.)
and Charpy.)
and a small portion of the caecum behind. (2) The ileo-caecal, inferior ileo-caecal
or ileo-appendicular fossa (recessus ileocaecalis inferior) (Fig. 880) is situated behind
the angle of junction of the ileum and caecum. It is formed by a fold of peritoneum,
the ileo-caecal fold (plica ileocaecalis), which Treves called the "bloodless fold."
Tuffier denies its non-vascularity, and Lockwood and Rolleston state that it con-
tains fat, muscular fibres, and arteries and veins derived from the appendicular ves-
sels and the anterior and posterior ileo-caecal vessels.1 The upper border of the fold
is attached to the ileum, opposite its mesenteric attachment, and the lower border,
passing over the ileo-crecal junction, joins the mesentery of the appendix, and
sometimes the appendix itself; hence this fold is sometimes called the ileo-appen-
dicular fold. Between the ileo-csecal fold and the mesentery of the vermiform
appendix is the ileo-caecal fossa. It is bounded above by the posterior surface of
the ileum and the mesentery; in front and below by the ileo-csecal fold, and behind
by the upper part of the mesentery of the appendix. (3) The retro-caecal or retro-colic
1 The Caecal Folds and Fossae. By Richard J. A. Barry.
THE PERITONEUM
1273
fossae (recessus retrocaecalis) (Fig. 881) are situated behind the caecum and ascend-
ing colon. There may be no fossa present. There may be one fossa; there are
usually two (external and internal retrocolic fossae) ; occasionally there are more
than two.1 The fossae are brought into view by raising the caecum. According to
Berry, one or other of the fossa is present in 30 per cent, of cases. Treves thinks
the retrocolic fossae are extremely rare. There may be one fossa (20 per cent, of
cases) or two fossae (10 per cent, of cases). If there is but one fossa it is the
internal that exists three times as often as the external. The retro-colic space,
if present, varies much in size and extent. In some cases it is sufficiently large
to admit the index finger and extends upward behind the ascending colon in
the direction of the kidney; in others it is merely a shallow depression. The
external retro-colic fossa is bounded and formed by two folds: one, the external
parieto-colic fold or the superior caecal fold, which is the outer layer of the ascend-
ing mesocolon, and is attached by one edge to the abdominal wall from the
lower border of the kidney to the iliac fossa and by the other to the postero-
ILEO-APPENDICULAR
APPENOICULAR
FOSSA
MESO-APPENDIX
INFERIOR
C/CCAL FOLD
RETRO-OECAL
FIG. 881. — The retro-csecal fossa. The ileum and csecum are drawn backward and upward. (Souligoux.)
external aspect of the colon ; and the other, the internal parieto-colic fold or inferior
caecal fold, which is the inner layer of the ascending mesocolon. The internal
retrocolic fossa is bounded externally by the internal parieto-colic fold, and is
bounded internally by the mesenterico-parietal fold, which is the insertion of the
mesentery into the iliac fossa.
3. The Intersigmoid Fossa (recessus intersigmoideus") . — The intersigmoid fossa
is constant in the foatus and common during infancy, but disappears in a large
percentage of cases as age advances. Upon drawing the sigmoid flexure upward,
the left surface of the sigmoid mesocolon is exposed, and on it will be seen a
funnel-shaped recess of the peritoneum, lying on the external iliac vessels, in the
interspace between the Psoas and Iliacus muscles. This is the orifice leading to
the fossa intersigmoidea, which lies behind the sigmoid mesocolon, and in front of
the parietal peritoneum. This fossa is produced by the incomplete fusion in the
foetus of the descending mesocolon with the parietal peritoneum. The fossa varies
1 The Caecal Folds and Fossae. By Richard J. A. Barry.
1274 THE ORGANS OF DIGESTION
in size; in some instances it is a mere dimple, whereas in others it will admit the
whole of the index finger.
Any of these fossae may be the site of a retro -peritoneal hernia. The pericsecal
fossae are of especial interest, because hernia of the vermiform appendix frequently
takes place into one of them, and may there become strangulated. The presence
of these pouches also explains the course which pus has been known to take in
cases of perforation of the appendix, where it travels upward behind the ascending
colon as far as the Diaphragm.1
Surgical Anatomy. — Study of the peritoneum by Robinson and others shows that absorption
takes place most rapidly from the region of the Diaphragm, less rapidly but still very actively from
the region of the small intestine, slowly from the pelvic region. Clinically we know that pelvic
peritonitis is not nearly so dangerous as peritonitis in the small intestine or Diaphragm areas, and
that peritonitis in the region of the Diaphragm is the most fatal form of the infection. After
abdominal operations in infected cases, it is well to elevate the head of the bed (Fowler's position),
so as to obtain the aid of gravity in draining septic fluids away from the dangerous region and
toward the safer region.2 In areas in which absorption is rapid, protective exudation is not apt to
form. In areas in which absorption is slow, inflammatory exudation is apt to circumscribe the
area and prevent diffusion. After an operation in a non-infected case, if salt solution has been
left in the abdominal cavity because of shock or hemorrhage, raising the foot of the bed will aid
rapid absorption of the fluid by favoring the natural current toward the Diaphragm and hurrying
the fluid to a region in which absorption is rapid. Dr. John B. Murphy's plan of treating general
peritonitis has proved remarkably successful. He does not remove the exudation of lymph which
is seen upon the peritoneum. This exudation is conservative, blocks up lymph spaces, and lessens
the absorption of dangerous toxins. He inserts a drainage tube into the peritoneal cavity above
the pubes, puts the patient erect or semi-erect in bed (Fowler's position), and administers salt
solution continuously by low pressure proctolysis. According to Murphy the lymph circulation
is reversed and the peritoneum becomes a secreting surface. Certain it is that the salt solution
absorbed from the rectum reaches the peritoneal cavity in large amounts and flows out of the
drainage tube.
The great omentum stores up fat, and, being movable, it is able to pass to different parts of
the peritoneal cavity. Dr. Robinson, in his work on the Peritoneum, describes its functions as
follows: "The omentum is the great protector against peritoneal infectious invasions. It builds
barriers of exudates to check infection. It is like a man-of-war, ready at a moment's notice to
move to invaded parts. It circumscribes abscesses; it repairs visceral wounds, and prevents
adhesions of mobile viscera to the anterior abdominal wall. It resists infectious invasions by
typical peritoneal exudates, and not by succumbing to absorbed sepsis. It is a director of peri-
toneal fluids, a peritoneal drain."
In abdominal wounds the omentum often protrudes: This structure frequently constitutes
or is part of a hernia, and is almost invariably present in umbilical hernia. As a result of
inflammation, it may become adherent to adjacent structures. Adhesions may be of service by
matting together the intestines and circumscribing infections. They may be harmful by
constricting the bowels and producing obstruction. A portion of the omentum may become
adherent to some other part and form a band, and under this band the gut may be caught and
strangulated. Omentum may adhere to and plug a perforation in a hollow viscus, and the sur-
geon may utilize it for the same purpose, or to cover a raw surface or overlie a suture line. The
omentum may be in the surgeon's way while operating. If it is, the patient is placed in the
Trendelenburg position (pelvis elevated).
Any tear or opening found by the surgeon in the great omentum must be closed with sutures,
because of the danger that intestine might enter and be caught in such an opening. A tumor
cut off from its proper blood-supply, for instance, an ovarian cyst with a twisted pedicle, may
continue to receive nourishment from adherent omentum, and gangrene may thus be prevented.
The lax character and shifting tendency of the subserous tissue explains the occurrence of
ptosis of the abdominal viscera and kidneys.
The vast number of nerves in the peritoneum accounts for the profound shock which follows
a wound, attends an intraperitoneal calamity, or which develops from infection. An infective
process of any portion of the peritoneum produces pain and reflex symptoms (vomiting,
abdominal rigidity, intestinal paresis, etc.).
The parietal peritoneum is very sensitive to pain, but not to touch; hence, after injecting a
local anaesthetic and opening the abdomen, a fairly satisfactory exploration can be made with
the finger.
The intestine, the mesentery, the stomach, the anterior margin of the liver, and the gall-bladder
are insensitive, and may be cut or even burned without pain.3
1 On the anatomy of these fossae, see the Arris and Gale Lectures by Moynihan, 1899.
2 Geore R. Fowler, in Medical Record, April 14, 1900.
E. L. Lennander, in Mittheilungen aus dem Grenzgebieten der Medicin und Chirurgie, Band x.,
Heft 1, 2.
THE PERITONEUM
1275
FIG. 882
FIG. 883
Three feet.
Six feet.
FIG. 884
FIG. 885
Nine feet.
Twelve feet.
FIG. 886
FIG. 887
Seventeen feet.
Twenty feet.
FIGS. 882, 883, 884, 885, 886, 887. — Diagrams showing the arrangement and variations of the loops of the
mesenteric vessels for various segments of the small intestine of average length. Nearest the duodenum the
mesenteric loops are primary, the vasa recta are long and regular in distribution and the translucent spaces
(lunettes) are extensive. Toward the ileo-colic junction, secondary and tertiary loops are observed, the vessels
are smaller and become obscured by numerous fat-tabs. (After Monks.)
1276 THE ORGANS OF DIGESTION
Viscera which obtain their innervation purely from visceral nerves are insensitive; those which
receive branches from somatic nerves are sensitive (Lennander).
The oblique origin of the mesentery causes this structure to form a sort of shelf. A hemor-
rhage or extravasation into the abdomen, to the right of the mesentery, tends to flow into the
right iliac fossa; one occurring on the left side flows into the pelvis. Monks points out that in
flushing the abdominal cavity the tube should not be aimlessly introduced, but should utilize
the mesentery on each side of an intestinal loop, to "conduct the tip of the irrigating tube to the
bottom of the two fossae."1 Monks also shows how the mesentery can be utilized to determine
the direction of an intestinal loop:
" Now, let us suppose that the surgeon has between his fingers a loop of bowel, and wishes
to determine its direction. He knows that one side of the loop is the left side of the intestine,
and that the corresponding side of the mesentery, if closely followed down to the mesenteric
root, will conduct him into the left fossa; he also knows that the other side of the bowel is its
right side, and that the mesentery on that side will conduct him into the right fossa. Now,
if his finger goes into the great fossa on the left side of the abdomen, after having closely fol-
lowed the mesentery down to its root and arranged his loop to be parallel with that root, he then
knows that the left and right sides of the intestine face to the left and right sides of the abdomen
respectively, and that the end of the loop which points downward is the end nearest the ileo-
csecal valve. He can determine the direction of the gut in a similar way in case his finger enters
the right fossa. All this would seem very simple were it not for the twists in mesentery and
intestine, which tend to mislead one. A little practice will usually enable one to recognize a twist
in the mesentery. This should be untwisted by rotation of the gut, after which the direction is
determined by another palpation of the mesenteric root."2
The studies made of the arrangement and variations of the loops of the mesenteric vessels by
Dr. Thomas Dwight3 have been utilized and expanded by Dr. George H. Monks in laying down
rules for the determination of the exact portion of small intestine which may be in the surgeon's
hand.4 His views are as follows:
"General Vascularity of the Mesentery near the Bowel. — Opposite the upper part of the bowel the
mesenteric vessels are distinctly larger than opposite any other part of it. These vessels grow
smaller and smaller as we pass downward until the lower third of the gut is reached, where they
remain about the same size as far as the ileo-caecal valve. The arrangement of the mesenteric
vessels has some features which intimately concern the subject in hand, and which I shall describe
with some detail. Diagrammatically speaking, the main branches of the superior mesenteric
artery unite with each other by means of loops, which are called for convenience 'primary loops;'
in some parts of the tube, 'secondary loops,' and even, occasionally, 'tertiary loops' are super-
imposed upon these. From these loops little straight vessels — the vasa recta already referred to
— run to the bowel, upon which they ramify, alternating, as a rule, as to the side of the intestine
which they supply. The mesenteric veins are arranged in a manner somewhat similar to the
arteries.
" The Loops of the Mesenteric Vessels (Figs. 882, 883, 884, 885, and 886).— Opposite the upper
part of the bowel there are only primary loops. Occasionally a secondary loop appears, but it
is small and insignificant as compared with the primary loops, which are large and quite regular.
As we proceed down the bowel secondary loops become more numerous, larger, and approach
nearer to the bowel than the primary loops in the upper part. As a rule, secondary loops
become a prominent feature at about the fourth foot.' As we continue farther downward, the
secondary loops (and, possibly, tertiary loops) become, still more numerous and the primary
loops smaller, the loops all the time getting nearer and nearer to the gut. Opposite the lower
part of the gut the loops generally lose their characteristic appearance, and are represented by
a complicated network.
" The Vasa Recta. — Opposite the upper part of the intestine the vasa recta are from three to
five centimetres long, when the loop of small intestine to which they run is lifted up so as to
put them gently on the stretch. They are straight, large, and regular, and rarely give off branches
in the mesentery. In the lower third they are very short, being generally less than one centimetre
in length. Here they are less straight, smaller, less regular, and have frequent branches in the
mesentery."
The translucency of the mesentery varies greatly ; in some parts it may be almost transparent,
in others almost or quite opaque. Its thinnest part is above. It is thickened below by fat, fibrous
tissue, and muscular tissue. In very fat subjects it may be impossible to see the vessels (Monks).
According to Monks, if a loop is raised and looked at against the light close to the gut ''little
transparent spaces" are seen between the vasa recta, and even in the thickest mesentery; some
of these "lunettes" exist along the upper portion of the intestine. As we descend in our exam-
ination, they grow smaller and become fatty, and disappear about the eighth foot of the intes-
1 Intestinal localization, by George H. Monks, Annals of Surgery, October, 1903. 2 Ibid.
3 Reports of the Meeting of American Anatomists, 1897. 4 Annals of Surgery, 1903.
THE STOMACH 1277
•
tine ' The same author shows that the mesentery of the lower third of the intestine, except in
the thinnest individuals, contains little collections of fat on the border of the mesentery, which
project toward the bowel and may even extend upon it.
THE STOMACH (VENTRICULUS) (Figs. 874, 888, 889, 891, 892).
The stomach is the principal organ of digestion. It is the most dilated part of
the alimentary canal, and is situated between the termination of the oesophagus
(cardid) and the commencement of the small intestine. Its form varies because
of varied conditions, but, as a rule, it is somewhat pyriform. It is placed, in
part, immediately behind the anterior wall of the abdomen and beneath the
Diaphragm. Viewing the stomach from in front it appears that the right margin
of the oesophagus is continued downward as the upper two-thirds of the lesser
curvature of the stomach, the remaining third of this border bending sharply
backward and to the right, to complete the smaller curvature (Fig. 888). The
greater curvature begins at the left border of the termination of the oesophagus in
a somewhat acute angle ; it then passes upward and to the left to the under surface
of the Diaphragm, with which it lies in contact for some distance, and then sweeps
downward with a convexity to the left, and, continued across the middle line of the
body, finally turns upward and backward, to terminate at the commencement of
the small intestine. It will thus be seen that the stomach may be divided into a
fundus (fundus ventriculi) and a middle portion or body (corpus ventriculi). The
portion of the body adjacent to the cardia being known as the cardiac portion (pars
cardiaca), the long axis of which is directed downward with a slight inclination
forward and to the right; and the portion adjacent to the pylorus being known as
the pyloric portion (pars pylorica), the long axis of which is horizontal or rather
upward with an inclination backward. Of the two openings, the cardiac orifice, by
which it communicates with the oesophagus, is situated slightly to the left of the
middle line of the body to the right of the fundus, or dilated upper extremity of the
stomach, and is directed downward ; the other,
the pyloric orifice, by which it communicates Fundus.
with the small intestine, is on a lower plane,
close to the right of the mid-line, and looks Car
directly backward.
Relations Of the Stomach. — The Stomach
lies in a space or chamber called the stomach
chamber (Fig. 874) . When distended the viscus
completely fills the space. When the stomach
is empty it lies upon the floor of the chamber, pvlorus
and the portion it has vacated is occupied by
the transverse colon, which ascends in front of
the Stomach and finally gets above it.' The ^- 888.-Diaggrarnmatic outline of the
anterior wall of the stomach chamber is formed
by the anterior abdominal wall. The roof is formed by the under surface of the
Diaphragm and the under surface of the left lobe of the liver. The floor is formed
by the left suprarenal capsule and the summit of the left kidney, the gastric face
of the spleen, the upper surface of the pancreas, the transverse mesocolon, and
the colon.2
Surfaces. — The stomach has two surfaces, called anterior and posterior surfaces,
and two borders, termed the greater and lesser curvatures.
In regard to the so-called anterior and posterior surfaces of the stomach, it
must be borne in mind that these names are not strictly correct, as the anterior
surface has a certain amount of inclination upward and the posterior downward .
1 Annals of Surgery, October, 1903.
2 Prof. Birmingham in Prof. Cunningham's Text-book of Anatomy.
1278 THE ORGANS OF DIGESTION
•
The Anterior, Upper or Parietal Surface (paries anterior}. — The anterior surface
is directed forward and to the right side. It has a somewhat flattened appearance
when the stomach is empty, but when it is full the surface becomes convex. It is
in relation with the Diaphragm ; the thoracic wall formed by the anterior parts of
the seventh, eighth, and ninth ribs of the left side; the left lobe of the liver; and
the anterior abdominal wall. Between the part covered by the liver and that
covered by the left ribs there is a triangular segment of the anterior wall of the
stomach, which is in contact with the abdominal wall and is the only part of the
stomach which is visible when the abdominal wall is removed and the viscera
allowed to remain in situ. Its area is about 40 sq. cm., and it is of great impor-
tance to the surgeon, as the stomach can readily be reached in this situation.
Occasionally the transverse colon may be found lying in front of the lower part
of the anterior surface of .the stomach. The whole of this surface of the stomach
is covered by peritoneum.
The Posterior, Lower or Visceral Surface (paries posterior}. — The posterior sur-
face of the stomach is directed backward and to the left. It is in relation with
the Diaphragm, the gastric surface of the spleen, the left suprarenal capsule, the
upper part of the left kidney, the anterior surface of the pancreas, the splenic
flexure of the colon, and the ascending layer of the transverse mesocolon. These
structures form a shallow concavity or bed, on which this surface of the stomach
rests. The transverse mesocolon intervenes between the stomach and the duodeno-
jejunal junction and commencement of the ileum. Its greater curvature is in
relation with the transverse colon and has attached to it the anterior two layers
of the great omentum. Almost the whole of this surface is covered with peri-
toneum, but behind the cardiac orifice there is a small portion of the stomach
which is uncovered by peritoneum and is in contact with the Diaphragm and fre-
quently with the upper portion of the left suprarenal capsule.
The Lesser Curvature (curvatura ventriculi minor). — The lesser curvature of the
stomach extends between the cardiac and pyloric orifices along the right border
of the organ. It descends in front of the left crus of the Diaphragm, along the left
side of the eleventh and twelfth thoracic vertebrae, and then turning to the right it
crosses the first lumbar vertebra and ascends to the pylorus. It gives attachment
to the two layers of the gastro-hepatic omentum, between which blood-vessels and
lymphatics pass to reach the organ.
The Greater Curvature (curvatura ventriculi major). — The greater curvature of
the stomach is directed to the left, and is four or five times as long as the lesser
curvature. Starting from the cardiac orifice, it forms an arch to the left with its
convexity upward, the highest point of which is on a level with the costal cartilage
of the sixth rib of the left side. It then passes nearly straight downward, with a
slight convexity to the left, as low as the costal cartilage of the ninth rib, and then
turns to the right to end at the pylorus. As it crosses the median line the lowest
edge of the greater curvature is about two fingers' breadth above the umbilicus.
The lower part of the greater curvature gives attachment to the two anterior
layers of the great omentum, between which layers vessels and lymphatics pass
to the organ.
The Cardia (Fig. 889). — The cardia is the point at which the oesophagus enters
the stomach wall. The opening is called the cardiac orifice or the oesophageal
opening. At the cardia the circular muscular fibres constitute a sphincter.
The Cardiac Orifice (Fig. 889). — The cardiac orifice is the opening by which the
oesophagus communicates with the stomach. It is therefore sometimes termed
the oesophageal opening. It is the most fixed part of the stomach, and is situated
about two inches below the highest part of the fundus on a level with the body
of the tenth or eleventh thoracic vertebra to the left and a little in front of the aorta.
This would correspond on the anterior surface of the body to the articulation of
THE STOMACH
1279
the seventh left costal cartilage to the sternum. It is placed far off from the surface
and is at least four inches back of the seventh left chondro-sternal articulation.
The Pylorus (Fig. 889).— The pylorus is the point at which the stomach passes
into the duodenum. The opening of communication is called the pyloric orifice.
At the pylorus the muscular fibres constitute a sphincter.
The Pyloric Orifice (Fig. 889). — The pyloric orifice communicates with the duod-
enum, the aperture being guarded by a valve (Fig. 890). Its position varies with
the movements of the stomach. When the stomach is empty the pylorus is situ-
ated just to the right of the medium line of the body, on a level with the upper
border of the first lumbar vertebra. On the anterior surface of the body its posi-
tion would be indicated by a point one inch below the tip of the ensiform cartilage
and a little to the right. As the stomach becomes distended the pylorus moves to
the right, and in a fully distended stomach may be situated two or three inches
to the right of the median line. The direction of the pylorus is upward and to
Cystic duct.
FIG. 889. — The mucous membrane of the stomach and duodenum with the bile-ducts.
the right, which position prevents " the weight of the gastric contents bearing
directly on the sphincter apparatus."1 The pylorus is on a somewhat higher level
than the lowest point of the stomach. Near the pylorus the stomach frequently
exhibits a slight dilatation, which is named the antrum of the pylorus (antrum
pyloricum). The pylorus is indicated by a constriction, the direction of which
is circular. The pylorus lies upon the neck of the pancreas behind. Above it
and in front of it is the liver.
The size of the stomach varies considerably in different subjects. When mod-
erately distended its greatest length, from the top of the fundus to the lowest part
of the greater curvature, is from ten to twelve inches and its diameter at the
1 W. J. Mayo, Medical Record, June 11, 1904.
1280
THE ORGANS OF DIGESTION
widest part from four to five inches. The distance between the two orifices is three
to six inches, and the measurement from the anterior to the posterior wall three
and a half inches. Its weight, according to Clendinning, is about four ounces and
a half, and its capacity in the adult male is five to eight pints. The stomach of a
newborn child holds about one ounce.
Alterations in Position. — There is no organ in the body the position and connections of which
present such frequent alterations as the stomach. When empty, it lies at the back part of the
abdomen, some distance from the surface, and is in the left hypochondriac region and the left
portion of the epigastric region. Its fundus is directed upward and backward toward the Dia-
phragm. The long axis of the viscus is nearly horizontal. Its pyloric end is directed upward
and backward, is situated close to or very slightly to the right of the middle line, covered in front
by the left lobe of the liver, and being on a level with the first lumbar vertebra. When empty,
the stomach assumes a more or less cylindrical form, especially noticeable at its pyloric end. The
entire viscus is small and contracted, and the pyloric region resembles the intestine. When the
stomach is distended, its surfaces, which are flattened when the organ is empty, become convex
and the shape becomes pyriform. The viscus becomes very oblique and approaches the vertical,
its long axis being downward, forward, and to the right. The greater curvature is elevated and
carried forward, so that the anterior surface is turned more or less upward and the posterior
surface downward, and the stomach is brought well against the anterior wall of the abdomen. Its
fundus expands and rises considerably above the level of the cardiac orifice; in doing this the
Diaphragm is forced upward, contracting the cavity of the chest; hence the dyspnoea complained
of, from inspiration being impeded. The apex of the heart is also tilted upward; hence the
oppression in this region and the palpitation experienced in extreme distention of the stomach.
The left lobe of the liver is pushed to the right side. When the stomach becomes distended
the change in the position of the pylorus is very considerable; it is shifted to the right, some
two or three inches from the median line, and lies under cover of the liver, near the neck of the
gall-bladder. In consequence of the distention of the stomach the lesser cul-de-sac bulges over
the pylorus, concealing it from view, and causing it to undergo a rotation, so that its orifice is
directed backward. When the stomach is greatly distended its lower border may enter the
umbilical and the left Irmbar regions. During inspiration the stomach is displaced downward
by the descent of the Diaphragm, and it is elevated by the pressure of the abdominal muscles dur-
ing expiration. Pressure from without, as from tight lacing, pushes the stomach down toward the
pelvis. In fact, in the female, because of tight lacing, the stomach may be to the left side of the
vertebral column and nearly vertical in direction, the lower portion being sharply angled upward
toward the pylorus, which lies underneath the liver. Besides the angulation, the lower end, the
stomach may have a median constriction, and there may even be an hour-glass stomach. The
descent of the stomach from tight lacing may cause the pancreas to become nearly vertical. In
disease the position and connection of the stomach may be greatly changed, from the accumula-
tion of fluid in the chest or abdomen, or from alteration in size of any of the surrounding viscera.
Variations according to Age. — In an early period of development the stomach is vertical, and in
the newborn child it is more vertical than later on in life, as owing to the large size of the liver
it is more pushed over to the left side of the abdomen, and the whole of the anterior surface is
covered by the left lobe of this organ.
On looking into the pyloric end of the stomach, the mucous membrane is found
projecting inward in the form of a circular fold, the pyloric valve (Fig. 890), leaving
a narrow circular aperture, about half an inch in
diameter, by which the stomach communicates with
the duodenum.
The Pyloric Valve (valvula pylori] (Fig. 890). — The
pyloric valve is formed by a reduplication of the mucous
membrane of the stomach,containing numerous circular
fibres, which are aggregated into a thick circular ring,
the pyloric sphincter (m. sphincter pylori) ; the longitu-
dinal fibres and serous membrane being continued
FI<;. 890.— Diagrammatic view over the fold without assisting in its formation (Fig. 890) .
of the coats of the stomach, duo- rni i • 11 i i j u j.u e
denum, and pylorus. The ridge is 1 he pylorus is normally kept closed by the action or
the pyloric valve. (Allan Thorn- thjg aggregation Qf circular fibres which'constitutes the
Sphincter muscle. During the early stage of digestion
it remains closed, but after a time opens now and then. The opening becomes
more frequent and the period of patency is prolonged as digestion advances.
THE STOMACH
1281
The diameter of the pylorus is uncertain. It is usually said to be half an inch.
But it is closed when the pylorus is at rest, and it can certainly dilate even in
a child to at least an inch and let bodies of this size pass through.
The Peritoneum. — The great omentum comes off from the greater curvature of
the stomach and passes to the transverse colon. The lesser omentum comes off
from the lesser curvature and passes to the liver. The gastro -splenic ligament or
omentum passes from the under surface of the stomach just below the greater
curvature to the spleen. A fold of peritoneum passes up from the stomach along
the left side of the oesophagus to the Diaphragm. This is the gastro -phrenic
ligament.
Supports of the Stomach. — The stomach lies on the bed of the stomach cham-
ber, which was described on p. 1277. The great omentum gives no support to
the stomach, neither does the gastro-splenic ligament, because of the movability
of the spleen. The lesser omentum does give support to the stomach and so do
FIG. 891. — The superficial muscular layer of the stomach, viewed from above and in front. (Spalteholz.)
the gastro -phrenic ligament and the hepato -duodenal ligament. The two chief
points of support are the attachment of the oesophagus to the Diaphragm and
the fixation of the duodenum to the front of the vertebral column.
Structure. — The wall of the stomach consists of four coats: serous, muscular,
areolar, and mucous, together with vessels and nerves.
The Peritoneal or Serous Coat (tunica serosa). — The peritoneal or serous coat
covers the entire surface of the organ, excepting along the greater and lesser
curvatures, at the points of attachment of the greater and lesser omenta; at
each curvature the two layers of peritoneum leave a small triangular space, to
which the peritoneum is not attached, although it is attached in front of it and
81
1282
THE ORGANS OF DIGESTION
back of it. Along these spaces the nutrient vessels and nerves pass. On the
posterior surface of the stomach, close to the cardiac orifice and below and to
the left of it, there is a smaller triangular area uncovered by peritoneum, where
the organ is in contact with the under surface of the Diaphragm, and it may be
with the left suprarenal body and the summit of the left kidney. When the
stomach is moderately distended this uncovered area measures about one and a
half inches from above downward, and about two inches from before backward.
At the left angle of this uncovered area the insertion of the great omentum
begins. At the right angle the gastric artery reaches the stomach.
The Muscular Coat (tunica muscularis) (Figs. 891 and 892). — The muscular coat
is situated immediately beneath the serous covering, to which it is closely connected.
It consists of three sets of fibres — longitudinal, circular, and oblique.
The Longitudinal Fibres (stratum longitudinale) are most superficial; they are
continuous with the longitudinal fibres of the oesophagus, radiating in a stellate
FIG. 892. — The middle and deep muscular layer of the stomach, viewed from above and in front. (Spalteholz.)
manner from the cardiac orifice. They are most distinct along the curvatures,
especially the lesser, but are very thinly distributed over the surfaces. At the
pyloric end they are more thickly distributed, and continuous with the longitudinal
fibres of the small intestine. The bundles of longitudinal muscle-fibre on the upper
and lower surfaces of the pylorus are particularly firm and distinct, and are called
the" pyloric ligaments (ligamenta pylori).
The Circular Fibres (stratum circulars) form a uniform layer over the whole
extent of the stomach, except the fundus, beneath the longitudinal fibres. At the
pylorus they are most abundant, and are aggregated into a circular ring or sphinc-
ter, which projects into the cavity, and forms, with the fold of mucous membrane
covering its surface, the pyloric valve (Fig. 890). They are continuous with the
circular fibres of the oesophagus.
THE STOMACH
1283
The Oblique Fibres (fibrae obliquae) arise at the left side of the cardia from the
circular fibres of the oesophagus. The fibres pass down in the anterior and pos-
terior walls. Those of the anterior wall are parallel to the lesser curvature and
almost reach the pylorus. Those of the posterior wall are more nearly transverse
to the long axis of the stomach (Spalteholz). These fibres gradually assume the
direction of the circular fibres and terminate in them. The layer of oblique fibres
is beneath the circular layer. Certain oblique muscular fibres encircle the fundus
of the stomach in a series of rings.
The Areolar or Submucous Coat (tela submucosa). — The areolar or submucous
coat consists of loose, filamentous, areolar tissue, connecting the mucous and
muscular layers. It supports the blood-vessels previous to their distribution to
the mucous membrane; hence it is sometimes called the vascular coat.
The Mucous Membrane (tunica mucosa) (Figs. 893, 894, and 895). — The
mucous membrane is thick; its surface smooth, soft, and velvety. In the fresh
state it is of a pinkish tinge at the pyloric end, and of a red or reddish-brown
Ridges between the alveoli.
Gastric Areas.
Rugae.
FIG. 893.— Mucous membrane of the stomach, from the
pars pyiorica, viewed from the surface. X 5. (Spalteholz.)
Gastric alveoli.
FIG. 894. — Mucous membrane of the stomach,
from the pars pyiorica, viewed from the surface.
X 16. (Spalteholz.)
color over the rest of the surface. In infancy it is of a brighter hue, the vascular
redness being more marked. It is thin at the cardiac extremity, but thicker toward
the pylorus. During the contracted state of the organ it is thrown into numerous
plaits or rugae (plicae mucosae) (Figs. 893 and 895, A), which for the most part
have a longitudinal direction, and are most marked toward the lesser end of the
stomach and along the greater curvature, and which contain also submucous tissue.
These folds are entirely obliterated when the organ becomes distended. A constant
fold exists at the pylorus (Fig. 890). It is called the pyloric valve, and is produced
by the presence beneath it of the Sphincter muscle.
Besides the large folds or rugae and the pyloric valve, there are numerous small
elevations of mucous membrane known as gastric areas (areae gastricae), which are
partly separated from each other by furrows and which vary greatly in shape
(Fig. 893). According to Spalteholz, each one of these elevations has an area of
several square millimetres.
1284
THE ORGANS OF DIGESTION
STRUCTURE OF THE Mucous MEMBRANE. — When examined with a lens the
inner surface of the mucous membrane presents a peculiar honeycomb appear-
MAMMILUK
MOUTHS OF GASTRIC
GLANDS, WITH GLAND
TUBES AT BOTTOM
DEPRESSION BETWEEN
TWO MAMMILLA
MOUTH OF
GASTRIC GLAND
FIG. 895. — The mucous membrane of the stomach. A, natural size; B, magnified 25 diameters. In A the
rugae and the mammillated surface are shown. In B the gland mouths (fqveolae gastricae), with the gland tubes
leading from some of them, and the ridges separating the mouths (plica villosae) are seen. (Cunningham.)
FIG. 896. — Pyloric gland.
FIG. 897. — Peptic gastric glan
ance, from being covered with small shallow depressions or alveoli (foveolae
gastricae) (Figs. 894 and 895, B) of a polygonal or hexagonal form, which vary
THE STOMACH 1285
from y^ to y^-g- °f an inch in diameter, and are separated by slightly elevated
ridges (plicae villosae). The ridges are most distinct at the pylorus. These
foveolae are within the areae gastricae. The ridges on section resemble villi. In
the bottom of the alveola are seen the orifices of minute tubes, the gastric glands
(Fig. 895 B), which are placed perpendicularly side by side throughout the
entire substance of the mucous membrane. The surface of the mucous membrane
of the stomach is covered by a single layer of columnar epithelium; it lines the
alveoli, and also for a certain distance the mouths of the gastric glands. This
epithelium commences very abruptly at the cardiac orifice, where the cells sud-
denly change in character from the stratified epithelium of the oesophagus. The
cells are elongated, and consist of two parts, the inner or attached portions
being granular, and the outer or free parts being clear and occupied by a muco-
albuminous substance.
The Gastric Glands. — The gastric glands are of three kinds: the true gastric
glands, the p^loiic glands, and the cardiac glands.
The True Gastric Glands (Fig. 897) are called also the oxyntic glands, the fundus
glands, and the peptic glands (glandulae gastricae propriae). They are distributed
throughout the entire fundus and body, and may be found even at the pylorus. They
are tubular in character, and are formed of a delicate basement-membrane, lined
with epithelium. The basement-membrane consists of flattened transparent endo-
thelial cells, with processes which extend between and support the epithelium. Into
the crypt of a true gastric gland three or more caecal tubes, branched or unbranched,
empty. The duct, however, in these glands is shorter than in the other variety,
sometimes not amounting to more than one-sixth of the whole length of the gland ;
it is lined throughout by columnar epithelium. At the point where the terminal
tubes open into the duct, and which is termed the neck, the epithelium alters, and
consists of short columnar or polyhedral, granular cells, which almost fill the tube,
so that the lumen becomes suddenly constricted, and is continued down as a very
fine channel. They are known as the chiof or the peptic or the central cells of the
glands, and furnish pepsin. Between these cells and the basement-membrane are
found other darker granular-looking cells, studded throughout the tubes at inter-
vals, and giving it a beaded or varicose appearance. These are known as the
parietal or oxyntic cells. Some of the parietal cells empty directly into the lumen
of the gland by secretory capillaries; others empty by a duct which divides into
secretory capillaries. The parietal cells secrete the acid of the gastric juice.
Between the glands the mucous membrane consists of a connective-tissue frame-
work with lymphoid tissue. In places this latter tissue, especially in early life, is
collected into little masses, which to a certain extent resemble the solitary glands
of the intestine, and are by some termed the lenticular glands of the stomach. They
are not, however, so distinctly circumscribed as the solitary glands.
The Pyloric Glands (glandulae pyloricae) (Fig. 896) are the branched tubular
glands, and secrete mucus.
They are placed most plentifully about the pylorus, but between the fundus and
pylorus, in the region known as the transitional or intermediate zone, both true
gastric glands and pyloric glands are found. Each pyloric gland consists of two
or three short, closed tubes opening into a common duct, the external orifice of
which is situated at the bottom of an alveolus. The caecal tubes are wavy, and
are of about equal length with the duct. The tubes and duct are lined through-
out with epithelium, the duct being lined by columnar cells continuous with the
epithelium lining the surface of the mucous membrane of the stomach, the tubes
with shorter and more cubical cells, which are finely granular. The pyloric
glands branch more frequently, are more curved in direction, and open into
deeper foveolae than the true gastric glands (Szymonowicz). They contain only
chief or peptic cells and do not possess parietal cells.
1286
THE ORGANS OF DIGESTION
PLEXUS
iENCATH THE
EPITHELIUM
GLANDULAR
PLEXUS
The Cardiac Glands are found about the oesophageal orifice. They resemble
the pyloric glands.
Beneath the mucous membrane, and between it and the submucous coat, is a
thin stratum of involuntary muscular fibre (muscularis mucosae), which in some
parts consists only of a single longitudinal layer; in others, of two layers, an inner
circular, and an outer longitudinal.
Vessels and Nerves. — The arteries supplying the stomach are — the gastric or
coronary, the pyloric and the right gastro-epiploic branch of the gastro-duodendal, the
left gastro-epiploic and vasa brevia from
the splenic. The gastric artery passes to the
lesser curvature just below the cardia. It
gives off the oesophageal branch, and passes
from left to right along the lesser curva-
ture of the stomach beneath the perito-
neum between the two layers of the lesser
omentum and upon the wall of the stomach.
It may in this course be a single vessel, or
may divide into two branches, which run
along each side of the lesser curvature (Fig.
899). If there is a single artery it gives off
six or seven descending branches to the an-
terior wall and about the same number to
FIG. 888.-TenninationS~o7thI blood-vessels in the posterior wall of the stomach. It also
and chappy )membrane °f the stomach' (p°irier gives branches to the lesser omentum. If
two vascular arches form, one gives branches
to the anterior wall of the stomach, the other to the posterior wall, and both to
the lesser omentum. The termination of the gastric anastomoses with the
pyloric branch or two rami of the pyloric branch of the hepatic artery. From
each arch six or seven descending branches come off to the anterior and posterior
ARTERIOLE
PLEXUS OF
BLOODVESSELS
IN SUBMUCOUS
TISSUE
CASTRO- DUODENAL
ARTERY
RIGHT GASTRO-
EPIPLOIC ARTERY
LEFT GASTRO-
EPIPLOIC ARTERY
FIG. 899. —The arteries of the anterior surface of the stomach. (Poirier and Charpy.)
walls of the stomach. The gastro -duodenal artery is given off by the hepatic.
From the gastro-duodenal comes the right gastro-epiploic. The left gastro-
epiploic comes from the splenic. The right gastro-epiploic artery passes from
right to left in the gastro-colic omentum below the greater curvature of the
THE STOMACH 1287
stomach. The left gastro-epiploic artery passes forward in the gastro-splenic
ligament to below the greater curvature of the stomach, and passes from left to
right along that curvature in the gastro-colic omentum, and joins the right gastro-
epiptoic artery. The gastro-epiploic arteries are not upon but are distinctly
below the stomach wall. From them numerous gastric branches are sent to the
anterior and posterior walls of the stomach, and they anastomose with branches
of the gastric and pyloric. Vasa brevia, four or five in number, arise from the
splenic, pass forward in the gastro-splenic ligament, and supply the fundus.
The arteries of the stomach lie first beneath the peritoneum, but soon enter the
muscular coat, supply it, pierce it, ramify in the submucous coat, and are finally
distributed to the mucous membrane. The arrangement of the vessels in the
mucous membrane is somewhat peculiar (Fig. 898). The arteries break up at
the base of the gastric tubules into a plexus of fine capillaries which run upward
between the tubules, anastomosing with each other, and ending in a plexus of
larger capillaries, which surround the mouths of the tubes and also form hexagonal
meshes around the alveoli.
The capillary networks about the glands give origin to the veins. The various
small veins unite and form a plexus in the submucous tissue (Fig. 898) . From this
plexus come branches which pass through the muscular coat and terminate in the
right gastro-epiploic branch of the superior mesenteric, the left gastro-epiploic branch
of the splenic, the veins to the splenic which correspond to the vasa brevia arteries,
and the gastric or coronary branch of the portal.
The lymphatics (Figs. 505 and 506) arise in the mucous membrane and terminate
in a network in the submucous tissue. From this network trunks arise which
perforate the muscular coat in the regions of the curvatures and terminate in the
sero-muscular collecting trunks.1
According to Cune"o, there are three groups of these collectors. Those from the
lesser curvature pass to the point where the gastric artery reaches the stomach and
enter the glands along the gastric artery. Those from the greater curvature pass
from left to right and enter the sub-pyloric glands. Those from -the fundus pass
from right to left and end in the splenic glands. Cuneo further pointed out that
the region drained by the collectors of the lesser curvature is divided from the
others by the line shown in Fig. 506. This division exists on both surfaces of
the stomach. The limit between the collectors which drain into the splenic
glands and those which drain into the sub-pyloric glands is also shown in
Fig. 506. Along the lesser curvature the lymph-glands are few in number and
are limited to the pyloric region, and the lymph- vessels are placed directly upon
the stomach wall. The lymph-glands and vessels are not upon but are distinctly
below the greater curvature.
The subserous and submucous lymphatic networks of the stomach communi-
cate with the corresponding networks of the oesophagus, but in all probability do
not communicate with the networks of the duodenum.
The nerves of the stomach come from the right and left vagus and from the solar
plexus of the sympathetic. The left vagus passes to the front of the stomach, and
the right nerve passes to the back, and they unite with the fibres of the sym-
pathetic. The fibres thus formed are mostly amyelinic. They form Auerbach's
plexus in the muscular coat between the circular and longitudinal fibres and
Meissner's plexus in the submucous coat, the latter plexus being formed by fibres
from the former. Fibres from Meissner's plexus ramify in the submucous coat
and terminate in the muscularis mucosae and the mucous membrane, branches
passing to the gastric glands and to just beneath the epithelium.
1 The Lymphatics. By Poirier, Cune'o, and Delamare. Translated and edited by Cecil H. Leaf.
1288 THE ORGANS OF DIGESTION
Movements and Innervation of the Stomach.
Movements. — It has apparently been demonstrated that the stomach "consists of two parts
physiologically distinct."1 The cardiac portion of the stomach is a food reservoir in which
salivary digestion continues; the pyloric portion is the seat of active digestion. Cannon affirms
that there are no peristaltic waves in the cardiac portion, but that as the food passes from the
pyloric portion into the intestines, tonic contraction of the -muscles of the fundus squeezes the
contents of the pyloric portion. Moritz, Levan, and Cannon assert that muscular activity is
chiefly manifested in the pyloric portion. In this portion during digestion there is a succes-
sion of peristaltic waves, which waves in the human being pass at the rate of three per minute
(Moritz). Cannon .points out that the efficiency of peristalsis in mixing the food depends
upon the contraction of the pyloric sphincter. So long as the sphincter holds, each constric-
tion-ring coursing from the middle to the end of the stomach presses the food into a blind pouch;
the food, unable to escape through the pyloric opening, has as its only outlet the opening in
the advancing ring. This is an admirable device for bringing the food under the influence of
the glandular secretions of the pyloric region. For, as a constriction occurs, the secreting sur-
face enclosed by the narrowed muscular ring is pressed close around the food within the ring.
As the constriction advances it continually presses inward fresh glandular tissue, and further-
more, as the constriction advances, a thin stream of food is continuously forced back through
the ring and thus past the mouths of the glands. The old view that the pyloric sphincter only
opens after several hours' continuance of the process of digestion and that then the stomach
empties at once is incorrect. It is emptied in small amounts which escape at frequent intervals
because of the intermittent opening of the pylorus. When the pylorus is open a wave of peri-
stalsis forces some of the material from the stomach into the duodenum (Cannon).
Cannon is of the opinion that the pyloric sphincter is caused to relax by the presence of free
hydrochloric acid in the pyloric portion of the stomach. When the pylorus is open acid chyme
passes into the duodenum and acid in the duodenum causes the pylorus to close. The acid
in the duodenum causes a flow of alkaline pancreatic juice and the acid is neutralized. "As
the neutralizing proceeds the stimulus closing the pylorus is weakened until the acid in the
stomach again opens the sphincter."2
Innervation. — The stomach, as previously shown, has nerve plexuses in its walls and is
connected to the brain, spinal cord, and sympathetic system. It is probable that gastric peri-
stalsis is due to a local reflex from Auerbach's plexus (Magnus), the local reflex being inaugu-
rated by local stimulation, which stimulation, in the words of Bayliss and Starling, "produces
excitation above and inhibition below the excited spot."3 Reversed peristalsis cannot occur
if "the reflex mechanism is intact" (Cannon). Cannon in the previously quoted article states
that cutting the vagus or splanchnic nerves does not destroy the reflex mechanism of the pylorus,
but, nevertheless, it is markedly affected by the central nervous system.
Surface Form (see p. 1280). — The cardiac orifice corresponds to the articulation of the
seventh left costal cartilage with the sternum. The pyloric orifice of the empty stomach is in
a vertical line drawn from the right border of the sternum, two and a half or three inches below
the level of the sterno-xiphoid articulation. According to Braune, when the stomach is dis-
tended, the pylorus moves considerably to the right, as much sometimes as three inches. The
fundus of the stomach reaches, on the left side, as high as the level of the sixth costal cartilage
of the left side, being a little below and behind the apex of the heart. The portion of the distended
stomach which is in contact with the abdominal walls, and is therefore accessible for opening in
the operations of gastrotomy and gastrostomy, is represented by a triangular space, the base of
which is formed by a line drawn from the tip of the tenth costal cartilage on the left side to the
tip of the ninth costal cartilage on the right, and the sides by two lines drawn from the extremity
of the eighth costal cartilage on the left side to the ends of the base line.
Surgical Anatomy. — Operations on the stomach are frequently performed, ulcers are excised,
malignant growths are removed with the associated lymphatic involvement, the entire stomach
may be removed for cancer, etc. By '' gastrotomy" is meant an incision into the stomach for the
removal of a foreign body, or the arrest of hemorrhage or for exploration, the opening being
immediately afterward closed — in contradistinction to " gastrostomy," the making of a more or
less permanent fistulous opening. Gastrotomy is probably best performed by an incision in the
linea alba, especially if the foreign body is large. The cut may reach from the ensiform car-
tilage to the umbilicus. The incision may be made over the body itself, where this can be felt,
or by one of the incisions for gastrostomy, to be mentioned shortly. The peritoneal cavity
is opened, and the point at which the stomach is to be incised decided upon. This portion is
then brought out of the abdominal wound and sponges carefully packed around. The stomach
is now opened by a transverse incision and the foreign body extracted. The wound in the
stomach is then closed by Lembert sutures — i. e., by sutures passed through the peritoneal,
1 Walter B. Cannon, Medical News, May 20, 1905, - Ibid. 3 Ibid.
MOVEMENTS AND INNERVATION OF THE STOMACH 1289
muscular and submucous coats in such a way that the peritoneal surfaces on each side of the
wound are brought into apposition, (raxtroxfomij was formerly done in two stages by the direct
method. The first stage consisted in opening the abdomen, drawing up the stomach into the
external wound, and fixing it there; and the second stage, performed from two to four days
afterward, consisted in opening the stomach. The operation is now done by a valvular method.
The following plan is known as the Ssabanejew-Frank operation. An incision is commenced
opposite the eighth intercostal space, two inches to the left of the median line, and carried
downward for three inches. By this incision the fibres of the Rectus muscle are exposed and
these are separated from each other in the same line. The posterior layer of the sheath, the
transversalis fascia and the peritoneum, are then divided, and the peritoneal cavity is opened.
Instead of the above incision, the curved incision of Fenger can be made at the margin of the
left costal cartilages. The anterior wall of the stomach is now seized and drawn out of the
wound and a silk suture passed through its submucous, muscular, and serous coats at the point
selected for opening the viscus. This is held by an assistant so that a long conical divertic-
ulum of the stomach protrudes from the external wound, and the parietal peritoneum and
the posterior layer of the sheath of the rectus are sutured to the base of the cone. A. second
incision is made through the skin, over the margin of the costal cartilage, above and a little to the
outer side of the first incision. If Fenger's incision were used, the second incision should be
above the margin of the cartilages. With a pair of dressing forceps a track is made under the
skin through the subcutaneous tissue from the one opening to the other and the diverticulum of
the stomach is drawn along this track by means of the suture inserted into it; so that its apex
appears at the second opening. A small perforation is now made into the stomach through
this protruding apex and its margin carefully and accurately sutured to the margin of the
external wound. The remainder of this incision and the whole of the first incision are then
closed in the ordinary way and the wound dressed.
In cases of gastric ulcer, perforation sometimes takes place, and this was formerly regarded
as an almost fatal complication. In the present day, by opening the abdomen and closing
the perforation, which is generally situated on the anterior surface of the stomach, a consider-
able percentage of cases are cured, provided the operation is undertaken within twelve to fifteen
hours after the perforation has taken place. The opening is best closed by bringing the peri-
toneal surfaces on either side into apposition by means of Lembert sutures.
Pylorectomy or excision of the pylorus is performed, particularly for early cancer, but is also
done for cicatricial stricture and for ulcer. The mortality after operation for cancer was, until
recently, very great, but of late years it has been notably reduced, though it is still much higher
than that which follows operation for any non-malignant condition.
In operating for cancer, bear in mind Cuneo's study of the lymphatics (page 806). These
observations indicate that the fundus and two-thirds of the greater curvature are free from
lymphatic involvement in pyloric cancer.1 In every operable case of cancer of the pylorus the
entire lesser curvature must be removed up to the gastric artery (Mikulicz's point), and the
greater curvature must be removed to the left of the involved glands (Hartmann's rule).
Gastro-enterostomy is an operation which establishes a fistulous communication between the
stomach and jejunum. The operation is often called gastro-jejunostomy. The opening may be
made upon either the anterior or the posterior wall of the stomach, between the cardia and the
seat of pyloric disease. The operation is employed for stricture of the pylorus (benign or
malignant), and occasionally for ulcer of the stomach.
Lorela's operation is digital divulsion of the pylorus for cicatricial stricture, the stomach being
incised transversely near the pylorus to admit the finger, and the wound in the stomach being
sutured after division has been effected. The operation has been abandoned, because contraction
recurs.
Pyloroplasty, or the Heineke-Mikulicz operation, displaced Loreta's operation. In this pro-
cedure an incision is made through the stricture in the direction of the long axis of the stomach
and bowel. By making traction on each side of the incision, the longitudinal wound assumes a
vertical direction, and sutures are inserted so as to close the wound in a vertical line. The method
of pyloroplasty devised by Finney, of Baltimore, makes a large permanent opening at the
most dependent part of the stomach, and is the most satisfactory method of which we are
possessed.2
Total gastrectomy is the removal of the entire stomach. It is only used for cancer. It was first
performed by Conner, of Cincinnati. The first successful operation was done by Schlatter, of
Zurich, in 1898. A number of successes have been reported. It is a justifiable operation only in
a case in which almost the entire stomach is cancerous, in which the viscus is movable, in which
there are no secondary deposits, and no irremovable diseased glands.
Gastro-gastrostomy is an operation employed in hour-glass stomach. In this operation an
anastomosis is made between the pyloric and cardiac ends of the stomach.
1 William J. Mayo, Annals of Surgery, March, 1904.
2 Johns Hopkins Hospital Bulletin, July, 1902.
1290 THE ORGANS OF DIGESTION
Gastroplication is the operation of suturing the stomach wall into folds or reefs, in order to
lessen its size. It is employed in some cases of gastric dilatation.
Gastroptosis is a condition in which the stomach is displaced downward. In some of these
cases the greater curvature almost reaches the level of the symphysis pubis, and the lesser curva-
ture is midway between the umbilicus and ensiform cartilage. The condition is usually associated
with enteroptosis and movable kidney (nephroptosis). In this condition the gastro-hepatic
omentum and the gastro-phrenic ligament are pulled upon and lengthened. The best operation
for gastroptosis was devised by Beyea. He applies sutures so as to make folds in and thus shorten
the stretched ligament and omentum. Thus the stomach is elevated to its proper position, and
its mobility is not lessened, as it is in other operations which suture it to the abdominal wall.
THE SMALL INTESTINE (INTESTINUM TENUE).
The small intestine is a convoluted tube, extending from the pylorus to the
ileo-caecal valve, where it terminates in the large intestine. It fills up the greater
part of the abdominal cavity and of the pelvic cavity. It is about twenty feet in
length,1 and gradually diminishes in size from its commencement to its termina-
tion. The diameter of the duodenum is almost two inches; the diameter of the
lower portion of the small intestine is little more than one inch. It is contained
in the central and lower part of the abdominal cavity, and is surrounded above
and at the sides by the large intestine; a portion of it extends below the brim of
the pelvis and lies in front of the rectum; it is in relation, in front, with the great
omentum and abdominal parietes; and connected to the spine by a fold of peri-
toneum, the mesentery (p. 1266). The small intestine is divisible into three portions
—the duodenum, the jejunum, and ileum.
The Duodenum (Figs. 900, 905, 906, 907, 908).
The duodenum has received its name from being about equal in length to the
breadth of twelve fingers (ten inches). It is the shortest, the widest, and the most
fixed part of the small intestine, being closely and firmly attached to the posterior
abdominal wall. It does not possess a mesentery. Somewhat more than the
upper half of the duodenum is placed in the epigastric region ; the remainder is in
the umbilical region. The duodenum, with the exception of the ascending portion,
is to the right of the median line. Its course presents a remarkable curve, which
in the adult, as regards the greater part of its extent, is horseshoe-shaped, though
sometimes, in consequence of the transverse portion being very short or alto-
gether wanting, it partakes more of the character of the letter V. The opening
of the horseshoe being directed upward and to the left. In children up to
the age of about seven the duodenum is annular. The two extremities of
the duodenum are nearly on the same level, the exit being slightly lower than the
entrance. The two ends are about two inches apart; and between them it
describes a regular curve embracing the head of the pancreas, the neck of which
lies between the two extremities of the ring.
In the adult the course of the duodenum is as follows: commencing at the
pylorus the direction of the first portion depends upon the amount of distention
of the stomach and therefore upon the position of the pylorus. When the stomach
is empty and the pylorus is situated at the right of the upper border of the first
lumbar vertebra, it is nearly horizontal and transverse ; but where the stomach is
distended, in consequence of the alteration of the position of the pylorus to the
right the proximal end of the duodenum also becomes altered in position, while the
1 Treves states that in one hundred cases the average length of the small intestine in the adult male was 22
feet 6 inches, and in the adult female 23 feet 4 inches ; but that it varies very much, the extremes in the male
being 31 feet 10 inches in one case and 15 feet 6 inches in another, a difference of over 15 feet He states that
he has convinced himself that the length of the bowel is independent, in the adult, of age, height, and weight.
ED. of 15th English edition.
THE DUODENUM
1291
distal end remains fixed and the direction of this portion of the bowel is now
antero-posterior. Whether directed transversely or antero-posteriorly, it reaches
Tributary to vena cara.
Hepatic artery, portal^
vein, and bile duct
Supra- renal
capsule.
'rura of Diaphragm.
Gastric artery.
Eight
renal
Vessels
Splenic
artery.
Splenic
vein.
FIG. 900. — Relations of duodenum, pancreas, and spleen. (From a cast by Professor Birmingham.1)
The dotted line represents the line of attachment of the transverse mesocolon.
the under surface of the liver, where it takes a sharp curve and descends along the
right side of the vertebral column, for a variable distance, generally to the body of
1 In the subject from which the cast was taken the left kidney was lower than normal.
1292
THE ORGANS OF DIGESTION
the fourth lumbar vertebra. It now takes a second bend, and passes across the
front of the vertebral column from right to left and finally ascends on the left side
of the vertebral column and aorta to the level of the upper border of the second
lumbar vertebra and there terminates in the jejunum. As it unites with the
jejunum it often turns abruptly forward, forming the duodeno-jejunal angle. Prof.
Omentum Minus
x Lesser Sac
\0
Hepatic
Artery
Portal
Vein
, • /'/ Greater ,
Omeiitum '{''
Majim Transverse Mesocolo
FIG. 901. — Diagram of cross-section of the first
FIG. 902.— Diagram of cross-section of the second part
part of the duodenum, to show its peritoneal of the duodenum, to show its peritoneal relations.
relations.
(Gerrish.)
Birmingham points out that the incomplete ring formed by the duodenum does
not lie throughout in the same plane. "Its greater part is placed in a transverse
vertical plane ; the middle portion bends strongly backward, around the right side
of the vena cava, and lies almost in a sagittal plane."1 From the above descriotion
FIG. 903. — Diagram of the third part of the
duodenum, to show its peritoneal relations.
(Gerrish.)
FIG. 904. — Diagram of the fourth part of the duodenum,
to show its peritoneal relations. (Gerrish.)
it will be seen that the duodenum may be divided for purposes of description
into four portions — superior, descending, transverse and ascending.
The First or Superior Portion (pars superior) (Figs. 900, 905, and 907) is
very variable in length, but is usually estimated as being about two inches.
Beginning at the pylorus, it ends at the level of the neck of the gall-bladder.
1 Prof. Cunningham's Text-book of Anatomy.
THE DUODENUM 1293
When the stomach is empty this portion of the duodenum is horizontal and
transverse; when the stomach is distended it extends from before backward. It
is the most movable of the four portions. It is almost completely covered by peri-
toneum derived from the two layers of the lesser omentum. A small part of its
posterior surface is not completely covered by peritoneum (Fig. 901). The first
inch of the superior portion of the duodenum is completely covered by perito-
neum; the lesser omentum is attached above and the greater omentum below
(Fig. 901). The other portion has only its anterior wall covered by peritoneum.
The posterior and lateral surfaces are uncovered by peritoneum and are near the
neck of the gall-bladder and the postcava. The first portion of the duodenum is
in such close relation with the gall-bladder that it is usually found to be stained
by bile after death, especially on its anterior surface. It is in relation above and in
front with the quadrate lobe of the liver, lying in a slight concavity, the impressio
duodenalis. It is also in relation above in part with the gall-bladder; behind with
the gastro-duodenal artery, the common bile-duct, and the portal vein; and
below with the head of the pancreas. The superior portion of the duodenum
crosses the transverse fissure of the liver, and by means of the superior flexure
of the duodenum (flexura duodeni superior) passes into the second or descending
portion beneath the caudate lobe.
The Second or Descending Portion (pars descendens) (Figs. 900, 905, and 907)
is between three and four inches in length, and extends from the neck of the gall-
bladder on a level with the first lumbar vertebra along the right side of the verte-
bral column as low as the body of the fourth lumbar vertebra. It is crossed in
its middle third by the transverse colon, the posterior surface of which is uncovered
by peritoneum and is connected to the duodenum by a small quantity of connective
tissue. The portions of the descending part of the duodenum above and below
this interspace are named the supracolie and infracolic portions, and are covered
in front by peritoneum (Fig. 902). The right side of the supracolie portion is
covered by peritoneum derived from the anterior surface of the right kidney, the
left side of the same portion being covered by the peritoneum forming the lesser
sac. The infracolic part is covered by the right leaf of the mesentery. Pos-
teriorly the descending portion of the duodenum is uncovered by peritoneum.
The descending portion of the duodenum is in relation, in front, with the trans-
verse colon, and above this with the right lobe of the liver, where it lies in the
impressio duodenalis for the second part of the duodenum; behind with the front of
the right kidney, to which it is connected by loose areolar tissue, the renal
vessels and the postcava; at its inner side is the head of the pancreas, and the
ductus communis choledochus; to its outer side is the hepatic flexure of the colon.
The common bile-duct passes downward behind the first portion of the duodenum,
descends to the inner side of the second portion, is joined by the pancreatic duct,
and the two ducts perforate the inner side of this portion of the intestine obliquely,
and empty into the duodenum by a common opening or by two openings at the
summit of a papilla, some three or four inches below the pylorus. The relations
of the second part of the duodenum to the right kidney present considerable
variations. The descending portion passes into the transverse portion by means
of the flexura duodeni inferior.
The Third, Pre-aortic, Horizontal or Transverse Portion (pars horizontalis
inferior) (Figs. 900, 905, and 907) varies much in length; when the duodenum
assumes the ordinary horseshoe form, it measures from two to three inches; but
when it presents the rarer V-shaped form, it is practically wanting or very much
reduced in length. The transverse portion is described as the horizontal part of
the ascending or last portion by those authors who divide the duodenum into three
parts instead of four. It commences at the right side of the fourth lumbar vertebra
and passes from right to left, with a slight inclination upward, in front of the great
1294
THE ORGANS OF DIGESTION
vessels and crura of the Diaphragm, and ends in the fourth portion in front of
or just to the left of the abdominal aorta. It is crossed by the superior mesen-
teric vessels and mesentery. The posterior surface rests upon the aorta, the post-
cava, and the crura of the Diaphragm. By its upper surface this portion of the
duodenum is in relation with the head of the pancreas. The front of the third
portion of the duodenum is covered by peritoneum except where the mesenteric
vessels and root of the mesentery cross it (Fig. 903). The left side of the termi-
nation of the ascending portion is also covered by peritoneum, and in this region
the duodenal fossae are found (p. 1270).
The Fourth or Ascending Portion of the Duodenum (pars ascendens] (Figs.
900, 905, and 907) is about two inches long. It ascends on the left side of the
vertebral column and aorta, as far as the level of the upper border of the second
lumbar vertebra, where it turns abruptly to the right and forward to become the
jejunum, forming the duodeno-jejunal angle or flexure (flexura duodenojejunalis)
LOBE OF
SPIGELIUS
CELLULAR MEMBRANE
CONNECTING THE PARTS
OFTHE DUODENAL Rl NG
BEHIND THE PANCREAS
DIAPHRAGM
CCELIAC AXIS
GANGLION OF
CCELIAC PLEXUS
SUPERIOR MESEN-
TERIC ARTE.RY
SUSPENSORY
MUSCLE OF
DUODENUM
FIG. 905. — Suspensory muscle of the duodenum or muscle of Treitz. (Poirier and Charpy.)
(Fig. 905). It is covered entirely in front and partly at the sides by peritoneum,
derived from the left portion of the mesentery (Fig. 904) . The superior mesen-
teric artery and vein are in front of it. It touches the left kidney, slightly over-
lapping its inner margin, and rests upon the left crus of the Diaphragm.
The first part of the duodenum, as stated above, is somewhat movable, but the
rest is practically fixed and is bound down to neighboring viscera and the posterior
abdominal wall by the peritoneum. In addition to this, the fourth part of the
duodenum and the duodeno-jejunal flexure is further bound down and fixed by a
structure called the Suspensory muscle of the duodenum or the suspensory ligament of
Treitz (m. suspensorius duodeni) (Fig. 905). This structure commences in the con-
nective tissue around the coeliac axis and left crus of the Diaphragm, and passes
downward to be inserted into the superior border of the duodeno-jejunal curve and
a part of the ascending duodenum, and from this it is continued into the mesentery.
It possesses, according to Treitz, some few plain muscular fibres mixed with the
THE DUODENUM
1295
fibrous tissue, of which it is principally made up. It is of little importance as a
muscle, but acts as a suspensory ligament.
SOUND IN DUC- CARUNCULA MINOR
TUS CHOLEDOCHUS OFSANTOR.NI
VALVULAE
CONNIVENTES
CARUNCULA
MAJOR
SOUND IN
ACCESSORY
PANCREATIC
DUCT OF
SANTORINI
LONGITUDINAL
FOLD
VALVULAE
CONNIVENTE8
.SOUND IN PANCREATIC
DUCT OF WIRSUNG
SOUND IN
DUCTU6 CHOLEDOCHUS
FIG. 906. — The interior of the duodenum. (Spalteholz.)
Gastric artery
Lower end of oesophagus
Cceliac axis
VA,
J5
Portal vein
Hepatic duct
Cystic duct
Hepatic artery
Kight suprarenal
capsule
Pyloric orifice
Right gastro-epiplaic
artery
Superior mesenteric
•3> **
<fl
.CVS
Spermatic vessels \Spermaticvessds
Inferior mesenteric artery
FIG. 907. — The duodenum, its four parts marked «, I, c, d. The liver is lifted up ; the greater part of the
stomach is removed, broken lines indicating its former position. (Testut.)
1296 THE ORGANS OF DIGESTION
Interior of the Duodenum (Fig. 906). — In the beginning of the duodenum valvulae
conniventes are absent. They begin to appear in the lower half of the first portion,
being at first trivial elevations irregularly placed. They become higher, regular,
and more numerous lower down, and near the termination of the duodenum are
strongly marked and closely placed transverse or spiral folds (Fig. 906 and
p. 1299). In the descending portion (Fig. 906) to the side and rear is a longi-
tudinal fold (plica longitudinalis duodeni), which is formed by the projection of
the bile-duct and pancreatic duct beneath the mucous membrane.
The caruncula major of Santorini or the bile papilla is a projection or tit in the
lower part of the longitudinal fold. At the summit of this papilla are seen two
openings, if the bile-duct and pancreatic duct have not united, or one common
opening for both of them, if they have united. One inch above and half an inch
or more in front of the bile papilla is a much smaller papilla, the caruncula minor
of Santorini (papilla duodeni [Santorini]), on the summit of which the accessory
pancreatic duct of Santorini opens.
Structure of the Duodenum. — The peritoneal coat (tunica serosa) has been de-
scribed. The muscular coat (tunica muscularis) is practically identical with the
muscular coat of the balance of the intestine. The bile-duct and pancreatic duct
FIRST GASTRO- GASTRO- INFERIOR
PART OF DUODENAL DUODENAL COZLIAC PANCREATICO-
DUODENUM ARTERY VEIN A,xl^ DUODENAL
VEIN
PANCREATICO-
DUODENAL
SUPERIOR
ARTERY
DUCTUS
CHOLEDOCHUS
ANASTOMOSIS OF THE
TWO PANCREATICO-
DUODENAL ARTERIES
FIG. 908. — The blood-vessels of the duodenum. (Poirier and Charpy.)
pass through it. The submucous coat (tela submucosa) contains lymph-nodes and
glands of Brunner (glandulae duodenales). These glands are particularly plenti-
ful in the first half of the duodenum (p. 1303). The mucous membrane is
thicker in the duodenum than in the rest of the small intestine, is covered with
villi, and from the lower half of the first portion down is formed into circular
folds or valvulae conniventes. In the descending part it exhibits the previously
described longitudinal fold.
Vessels and Nerves. — The arteries (Fig. 908) supplying the duodenum are the
pyloric and pancreatico -duodenal branches of the hepatic, and the inferior pancreatico-
duodenal branch of the superior mesenteric. The veins (Fig. 908) correspond to
the arteries. The superior duodenal vein passes into the superior mesenteric, and
the inferior duodenal vein passes into the portal. The lymphatics pass along with
the pancreatico-duodenal arteries, glands being present here and there, and
terminate in the glands about the coeliac axis. The duodenal fossae are described
on p. 1270. The nerves are derived from the solar plexus.
THE JEJUNUM AND ILEUM 1297
The Jejunum and Ileum (Figs. 875, 877, 878, 880, 905).
The remainder of the small intestine from the termination of the duodenum
comprises the jejunum and ileum; the former name being given to the upper two-
fifths and the latter to the remaining three-fifths. Spalteholz and others call all of
the small intestine below the duodenum the intestinum tenue mesenteriale. There
is no morphological line of distinction between the jejunum and ileum, and the
division is arbitrary; but at the same time it must be noted that the character of
the intestine gradually undergoes a change from the commencement of the jeju-
num to the termination of the ileum, so that a portion of the bowel taken from
these two situations would present characteristic and marked differences. These
are briefly as follows:
Differences between the Jejunum and Ileum. — If the jejunum high up is con-
trasted with the ileum low down, it is noted that the former is thicker, of greater
diameter, contains more blood-vessels, and hence is more distinctly red, has well-
marked valvulae conniventes, but a few small-sized Peyer's patches, and the villi
are short and broad. In the ileum large Peyer's patches are present in numbers,
and the villi are thin (Prof. Birmingham).
The Jejunum (intestinum jejunum). — The jejunum, which derives its name
from the Latin word jejunus (empty), because it was formerly supposed to be
empty after death, is wider, its diameter being about one inch and a half, and is
thicker, more vascular, and of a deeper color than the ileum, so that a given length
weighs more. Its valvulae conniventes are large and thickly set and its villi are
larger than in the ileum. The glands of Peyer are almost absent in the upper part
of the jejunum, and in the lower part are less frequently found than in the ileum,
and are smaller and tend to assume a circular form. Brunner's glands are only
found in the upper part of the jejunum. By grasping the jejunum between the
finger and thumb the valvulae conniventes can be felt through the walls of the
gut; these being absent in the lower part of the ileum, it is possible in this way
to distinguish the upper from the lower part of the small intestine.
The Ileum (intestinum ileum). — The ileum (so called from the Greek word
ei'te'tv, to twist, on account of its numerous coils and convolutions) is placed
below and to the right of the jejunum. It is narrower, its diameter being one inch
and a quarter, and its coats are thinner and less vascular than those of the jejunum.
It possesses but few valvulae conniventes, and they are small and disappear entirely
toward its lower end, but Peyer's patches are larger and more numerous. The
jejunum for the most part occupies the umbilical and left iliac regions, while the
ileum occupies chiefly the umbilical, hypogastric, right iliac, and pelvic regions,
and terminates in the right iliac fossa by opening into the inner side of the com-
mencement of the large intestine. The upper portion of the jejunum passes to
the left of the duodeno-jejunal flexure, and is in relation with the under surface
of the pancreas and the transverse mesocolon. The lower portion of the ileum is
in the pelvis and rises from above the brim, passing upward, backward, and to the
right to reach the ileo-caecal opening. Treves points out that another portion of
the small intestine may be in the pelvis, viz., the portion with the longest mesentery.
This is a portion somewhere between a point six feet from the duodenum and a
point eleven feet from the duodenum. The jejunum and ileum are attached to the
posterior abdominal wall by an extensive fold of peritoneum, the mesentery(p. 1266),
which allows the freest motion, so that each coil can accommodate itself to changes
in form and position. The mesentery is fan-shaped; its posterior border, about
six inches in length, is attached to the abdominal wall from the left side of the
second lumbar vertebra to the right iliac fossa (Fig. 875). Its length is about eight
inches from its commencement to its termination at the intestine, and it is rather
longer about its centre than at either end of the bowel. According to Lockwood,
82
1298 THE ORGANS OF DIGESTION
it tends to increase in length as age advances. Between the two layers of which
it is composed are contained blood-vessels, nerves, lacteals, and lymphatic glands,
together with a variable amount of fat.
Meckel's Diverticulum (diverticulum ilei). — Occasionally there may be found
connected with the lower part of the ileum, on an average about three feet from
its termination, a blind diverticulum or tube, varying in length, but averaging
about two inches, and being of about the same diameter as the piece of- intestine of
which it is a part. Sometimes only a portion of the proximal end is open and
the balance of the structure is obliterated and shrunk to a fibrous cord. In other
cases the diverticulum is actually of greater diameter than the intestine. It
usually is at a right angle to the intestine, but may take almost any direction.
In most cases it has a mesentery. It is attached to and communicates with the
lumen of the bowel by one extremity, and by the other is unattached or may be
connected with the abdominal wall or with some other portion of the intestine
by a fibrous band. This is Meckel's diverticulum, and represents the remains of
the vitelline or omphalo-mesenteric duct, the duct of communication between the
umbilical vesicle and the alimentary canal in early foetal life.
Structure of the Small Intestine, including the Duodenum.— The wall of
the small intestine is composed of four coats — serous, muscular, areolar or sub-
mucous, and mucous.
The Serous Coat (tunica serosa). — The relation of the peritoneum to the duod-
enum has been described. The remaining portion of the small intestine is sur-
rounded by the peritoneum, excepting along its attached or mesenteric border;
here a space is left for the vessels and nerves to pass to the gut.
The Muscular Coat (tunica muscularis). — The muscular coat consists of two
layers of fibres, an external or longitudinal layer and an internal or circular
layer.
The Longitudinal Fibres (stratum longitudinale) are thinly scattered over the
surface of the intestine, and are more distinct along its free border.
The Circular Fibres (stratum circular -e) form a thick, uniform layer; they sur-
round the cylinder of the intestine in the greater part of its circumference, and are
composed of plain muscle-cells of considerable length. The muscular coat is
thicker at the upper than at the lower part of the small intestine.
The Areolar or Submucous Coat (tela submucosa). — The areolar or submucous
coat connects together the mucous and muscular layers. It consists of loose,
filamentous areolar tissue, which forms a bed for the subdivision of the nutrient
vessels, previous to their distribution to the mucous surface.
The submucous coat contains lymph-nodules (noduli lymphatici). Each nodule
is pyramidal or pear-shaped, and the apex lies in the mucous membrane and forms
a rounded elevation. These rounded elevations mark the solitary glands and
Fever's patches (Figs. 909, 911, and 918), and in nowise resemble villi. In the
duodenum the submucous tissue contains the duodenal glands. The submucous
tissue is prolonged into the valvulae conniventes. It contains blood-vessels, Meiss-
ner's plexus of nerves, and lymph-vessels.
The Mucous Membrane (tunica mucosa}. — The mucous membrane is thick and
highly vascular at the upper part of the small intestine, but somewhat paler and
thinner below. It consists of the following structures: next the areolar or sub-
mucous coat is a layer of unstriped muscular fibres, the muscularis mucosae ; internal
to this is a quantity of retiform tissue, enclosing in its meshes lymph-corpuscles,
and in which the blood-vessels and nerves ramify. Lastly, a basement-membrane,
supporting a single layer of epithelial cells, which throughout the intestines are
columnar in character. They are granular in appearance, and each possesses a
clear, oval nucleus. At their superficial or unattached end they present a distinct
layer of highly refracting material, marked by vertical striae, which were formerly
THE JEJUNUM AND ILEUM
1299
believed to be minute channels by which the chyle was taken up into the interior
of the cell, and by them transferred to the lacteal vessels of the mucous membrane.
MOUTHS OF GLANDS SOLITARY GLAND
OF LIEBERKUHN
FIG. 909. — Free surface of the mucous membrane of the small intestine, showing villi, solitary glands,
and openings of the intestinal glands. Semidiagrammatic. (Testut.)
The mucous membrane presents for examination the following structures con-
tained within it or belonging to it:
Valvulae conniventes.
Villi.
Simple follicles.
Duodenal glands.
... j i f Solitary glands.
Lymphatic nodules \ n /
( reyer s or agminate glands.
The Valvulae Conniventes or the Valves of Kerkring (plicae circulares [Kerkringi])
(Fig. 910) are large folds or valvular flaps projecting into the lumen of the bowel.
They are composed of reduplications or folds of the mucous membrane, the two
layers of the fold being bound together by submucous tissue; they contain no
muscular fibres, and, unlike the folds in
the stomach, they are permanent, and
are not obliterated when the intestine is
distended. The majority extend trans-,
versely across the cylinder of the intestine
for about one-half or two-thirds of its
circumference, but some form complete
circles, and others have a .spiral direc-
tion; the latter usually extend a little
more than once around the bowel, but
occasionally two or three times. The
spiral arrangement is the characteristic
one of the shark family of fishes. The
larger folds are about one-third of an
inch in depth at their broadest part; but
the greater number are of smaller size.
The larger and smaller folds alternate
with each other. They are not found at the commencement of the duodenum,
but begin to appear about one or two inches beyond the pylorus. In the lower
part of the descending portion, below the point where the bile and pancreatic
ducts enter. the intestine, they are very large and closely approximated. In
the transverse portion of the duodenum and upper half of the jejunum they
FIG. 910. — Valvulae conniventes in the upper part
of the small intestine. (Poirier and Charpy.)
1300
THE ORGANS OF DIGESTION
are large and numerous; and from this point, down to the middle of the ileum,
they diminish considerably in size. In the lower part of the ileum they almost
entirely disappear; hence the comparative thinness of this portion of the intes-
tine as compared with the duodenum and jejunum. The valvulae conniventes
retard the passage of the food along the intestine, and afford a more extensive
surface for absorption.
The Villi (villi intestinales] (Figs. 909, 911, 912, 913, and 918) are minute, highly
vascular processes, never larger than one millimetre, projecting from the mucous
membrane of the small intestine throughout its whole extent, and giving to its
surface a velvety appearance. They spring from the valvulae conniventes and also
from the spaces between them. In shape, according to Rauber, they are short
and leaf-shaped in the duodenum, tongue-shaped in the jejunum, and filiform
MUCOUS COAT
PLANE OF MU-
COUS SURFACE
FIG. 911. — Mucosa of small intestine in ideal vertical cross-section. (Testut, after Heitzmann.)
in the ileum. They are largest and most numerous in the duodenum and
jejunum, and become fewer and smaller in the ileum. Krause estimates their
number in the upper part of the small intestine at from fifty to ninety in a square
line; and in the lower part from forty to seventy, the total number for the whole
length of the intestine being about four millions.
STRUCTURE OF THE VILLI (Figs. 912 and 913). — The structure of the villi has
been studied by many eminent anatomists. We shall here follow the description
of Watney,1 whose researches have a most important bearing on the physiology of
that which is the peculiar function of this part of the intestine, the absorption of fat.
The essential parts of a villus are — the lacteal vessel, the blood-vessels, the
epithelium, the basement-membrane and muscular tissue of the mucosa, these
structures being supported and held together by retiform lymphoid tissue.
1 Phil. Trans., vol. clxv. part ii.
THE JEJUNUM AND ILEUM
1301
These structures are arranged in the following manner : situated in the centre
of the villus is the lacteal, terminating near the summit in a blind extremity;
Tunica
Blood capillaries^^
Ciiticular border
r~ Epithelium
Nucleus of
'wandering cell
jagi _. Nucleus of smooth
muscle cell
lymph
space
f:
V
*V -.f'":
^4* *' »
al»'lo
o
\ffitt
if:-** f ^%
^5»*' •«-•/)
SS^iSJ „
/ ^^» ? "
fW /o 'J-Wlt * . <S»
'c_ A>. . - .. *lL
•'-«
•'*.
oblet cells
«« w* .g^^i
, «»««».
iS. **JUr«g» I
FIG. 912. — Longitudinal section through the end of a villus from the small intestine of a cat. X 450.
Capillaries.
Lymph trunk.'
'm — Lymph trunk.
m Capillaries.
Small artery.'' Lymphatic plexus.
FIG. 913. — Villi of small intestine. (Cadiat.)
1302
THE ORGANS OF DIGESTION
running along this vessel are unstriped muscular fibres; surrounding it is a plexus
of capillary vessels, the whole being enclosed by a basement-membrane, and cov-
ered by columnar epithelium. Those structures which are contained within the
basement-membrane — namely, the lacteal, the muscular tissue, and the blood-
vessels— are surrounded and enclosed by a delicate reticulum which forms the
matrix of the villus, and in the meshes of which are found large, flattened cells
with oval nuclei, and, in smaller numbers, lymph-corpuscles. These latter are
to be distinguished from the larger cells of the villus by their behavior with
reagents, by their size, and by the shape of the nucleus, which is spherical.
Transitional forms, however, of all kinds are met with between the lymph-cor-
puscles and the proper cells of the villus. Nerve-fibres are contained within the
villi; they form ramifications throughout the reticulum.
The lacteals are in some cases double, and in some animals multiple. Situated
in the axis of the villi, they commence by dilated caecal extremities near to, but
not quite at, the summit of the villus. The walls are composed of a single layer
of endothelial cells, the interstitial substance between the cells being continuous
with the reticulum of the matrix.
CALCI FORM
CELL
GLANDULAR
CELL
Fio. 914. — Section of a gland of Lieberkiihn in the mouse.
(Paneth.)
FIG. 915. — Transverse section of crypts of
Lieberkflhn. (Klein and Noble Smith.)
The muscular fibres are derived from the muscularis mucosae, and are arranged
in bundles around the lacteal vessel, extending from the base to the summit of the
villus, and giving off laterally individual muscle-cells, which are enclosed by the
reticulum, and by it are attached to the basement-membrane.
The blood-vessels form a plexus between the lacteal and the basement-mem-
brane, and are enclosed in the reticular tissue; in the interstices of the capillary
plexus, which they form, are contained the cells of the villus.
These structures are surrounded by the basement-membrane, which is made
up of a stratum of endothelial cells, and upon which is placed a layer of columnar
epithelium. The reticulum of the matrix is continuous through the basement-
membrane (that is, through the interstitial substance between the individual
endothelial cells) with the interstitial cement substance of the columnar epithelial
cells on the surface of the villus. Thus we are enabled to trace a direct continuity
between the interior of the lacteal and the surface of the villus by means of the
reticular tissue, and it is along this path that the chyle passes in the process of
absorption by the villi; that is to say, it passes first of all into the columnar
epithelial cells, and, escaping from them, is carried into the reticulum of the villus,
and thence into the central lacteal.
THE JEJUNUM AND ILEUM
1303
The Simple Follicles, Intestinal Glands, Crypts or Glands of Lieberkiihn (glandulae
intestinales [Lieberkiihni]) (Figs. 914, 915, and 918) are found in considerable
numbers over every part of the mucous membrane of the small intestine. They
consist of minute tubular depressions of the mucous membrane, arranged per-
pendicularly to the surface, upon which they open by small circular apertures.
They may be seen with the aid of a lens, their orifices appearing as minute dots
scattered between the villi (Fig. 909). Their walls are thin, consisting of a base-
ment-membrane lined by columnar epithelium, and covered on their exterior by
capillary vessels.
The Duodenal or Brunner's Glands (glandulae duodenales [Brunneri]) are limited
to the duodenum and commencement of the jejunum. They are small, flattened,
granular bodies embedded in the submucous areolar tissue, and open upon the
surface of the mucous membrane by minute excretory ducts. They are most
numerous and largest near the pylorus. They are small, compound, acino-tubular
glands, and much resemble the small glands which are found in the mucous mem-
... -Capillary network.
FIG 916. — Transverse section through the equatorial plane
of three of Peyer's follicles from the rabbit.
FIG. 917. — Free surface of a Peyer's patch.
(After Quain.)
brane of the mouth. They are believed by Watney to be direct continuations of
the pyloric glands of the stomach. They consist of a number of tubular alveoli,
lined by epithelium, and opening by a single duct on the inner surface of the
intestine.
The Lymph Nodules (nodidi lymphatici) are small pyriform structures. The
bodies of the nodes are in the submucous coat; the apices are in the mucous mem-
brane, which is thrown by them into rounded elevations. They are divided into
solitary glands and Peyer's glands.
The solitary glands (noduli lymphatici solitarii) (Figs. 909 and 911) are found
scattered throughout the mucous membrane of the small intestine and the large
intestine. In the small intestine they are most numerous in the lower part of the
ileum, upon and between the valvulae conniventes. They are small, round, whitish
bodies, from one-twenty-fourth of an inch to one-quarter of an inch in diameter.
Their free surface is covered with villi, and each gland is surrounded by the
openings of the follicles of Lieberkiihn. They are now recognized as lymph-
1304
THE ORGANS OF DIGESTION
nodules. They consist of a dense interlacing retiform tissue closely packed with
lymph-corpuscles and permeated with an abundant capillary network. The inter-
spaces of the retiform tissue are continuous with larger lymph-spaces at the base
of the gland, through which they communicate with the lacteal system. They
are situated partly in the submucous tissue, partly in the mucous membrane,
whence they form slight projections of its epithelial layer, after having pene-
trated the muscularis mucosae. The villi situated on them are generally absent
from the very summit (or "cupola," as Frey calls it) of the gland.
Peyer's glands, Peyer's patches, the agminated glands or the tonsillae intestinales
(noduli lymphatici aggregati [Peyeri]) (Figs. 916, 917, and 918) may be regarded as
aggregations of solitary glands, forming circular or oval patches from twenty-five
to forty in number, and varying in length from half an inch to four inches. They
are largest and most numerous in the ileum. In the lower part of the jejunum
they are small, of a circular form, and few in number. They are occasionally seen
in the duodenum. They are placed lengthwise in the intestine, and are situated
INTESTINAL VILLUS
GLAND OF LIEBERKUHN
CHYLI FERGUS
DUCT
SUMMIT OF
FOLLICLE
MIDDLE FOLLICULAR
ZONE
PERIFOLLICULAR
LYMPHATIC ZONE
INFERIOR LYM-
PHATIC PLEXUS
FIG. 918. — Vertical cell of a Peyer's patch in a man with the lymphatic vessels injected. (Frey.)
in the portion of the tube most distant from the attachment of the mesentery.
Each patch is formed of a group of the above-described solitary glands covered
with mucous membrane, and in almost every respect are similar in structure to
them. They do not, however, as a rule, possess villi on their free surface. Each
patch is surrounded by a circle of the crypts of Lieberkiihn. They are best marked
in the young subject, becoming indistinct in middle age, and sometimes altogether
disappearing in advanced life. They are largely supplied with blood-vessels,
which form an abundant plexus around each follicle and give off fine branches
which permeate the lymphoid tissue in the interior of the follicle. The lacteal
plexuses which are found throughout the small intestine are especially abundant
around these patches; here they form rich plexuses with sinuses around the glands
(Fig. 918), In typhoid fever there is ulceration of Peyer's patches.
Vessels and Nerves. — The arteries (vasa intestini tennis] are branches of the
superior mesenteric (Fig. 423) and ascend within the mesentery, forming single,
double, or even tertiary loops (Figs. 882, 883, 884, 885, 886, 887, and 919). The
terminal branches reach the intestine, and each branch divides into two, one going
to each side of the intestine and passing transversely around it. At first they are
THE JEJUNUM AND ILEUM
1305
directly beneath the peritoneum, but after a time they pass to the submucosa
and form a plexus, from which branches go to the mucous membrane. Some
of these enter the villi; others form plexuses about the glands of Lieberkiihn
(Birmingham).
FIG. 919. — A loop of small intestine, showing the mode of distribution of the arteries. (Testut.)
Dr. George H. Monks1 points out that opposite the upper portion of the bowel
the mesenteric vessels form only primary loops ; as we pass down secondary loops
appear, become larger and more and more numerous, and actually prominent
features about the fourth foot. As we descend the secondary
loops become larger and more numerous and the primary
become smaller. All the time the loops get nearer and
nearer to the bowel. Tertiary loops may appear. Opposite
the lower part of the ileum the loops cease to be character-
istic and they form a network. (Monks's views are fully
set forth on p. 1276.) In the upper part of the gut the vasa
recta are from 3 to 5 cm. long, when the loop of small intes-
tine to which they run is lifted up so as to put them gently
on the stretch. They are straight, large, and regular, and
rarely give off branches in the mesentery. In the lower third
they are very short, being generally less than 1 cm. in length.
Here they are less straight, smaller, less regular, and have
frequent branches in the mesentery.
The veins correspond to the arteries, and the venous
blood passes to the superior mesenteric vein, which, it will be
remembered, unites with the splenic vein to form the portal
vein. The mesenteric veins are devoid of valves.
The lacteals are lymphatics (Figs. 911, 912, 913, and
918) which arise in the villi. Lymphatics also begin in
sinuses at the base of the solitary glands and as li/nijtlt-
nodes in the submucous coat. Peyer's patches are aggre- ^^^BBBi^
gations of lymph-nodes. There is an extensive lymphatic FIG. 920.— Nerve endings
I ,1 i ,1 • ,i i ' in the villi of the small in-
plexus in the submucous coat, another in the muscular coat, testineof arabbit. (Muiier.)
another under the peritoneum. The submucous plexus
is formed by lymphatics from the villi and mucous membrane. This plexus
is joined by lymphatics from the bases of the solitary glands, and the lymph
passes by vessels to larger vessels at the mesenteric border of the gut. The
muscular lymphatics are placed between the two muscular layers. They
1 Annals of Surgery, May, 1903.
1306
THE ORGANS OF DIGESTION
form a plexus and communicate freely with the lymphatics from the mucous
membrane, and empty themselves in the same manner into the commencement
FIG. 921. — Meissner's plexus. (Ramon y Cajal.)
Multipolar ganglion-cells.
Single ganglion-cell.
FIG. 922.— Meissner's plexus. (Klein and Noble Smith.)
THE LARGE INTESTINE
1307
of the lacteal vessels at the attached border of the gut. The vessels from all
sources of lymphatic supply pass up between the two layers of the mesentery,
being connected with the mesenteric glands (Fig. 507), and unite to form a trunk,
the intestinal lymphatic trunk, which opens into the receptaculum chyli, or the
vessels unite to form several trunks, which open separately into the receptaculum
chyli.
The nerves of the small intestine (Figs. 920, 921 , and 922) are derived from the
coeliac plexus about the superior mesenteric artery, which is one of the divisions
of the solar plexus. They pass along within the mesentery with the superior mesen-
teric artery and reach the intestine. They pass to the plexus of nerves and ganglia
situated between the circular and longitudinal muscular fibres (Auerbach's plexus),
from which the nerve branches are distributed to the muscular coats of the
intestine. From this plexus a secondary plexus is derived (Meissner's plexus).
It is formed by branches which have perforated the circular muscular fibres
(Fig. 922). This plexus lies between the muscular and mucous coats of the intes-
tine. It is also gangliated, and from it the ultimate fibres pass to the muscularis
mucosae, to the villi, and to the mucous membrane. The nerves of the intestine
are amyelinic, and some of the fibres are derived from the vagus.
THE LARGE INTESTINE (INTESTINUM CRASSUM) (Figs. 812, 874, 875, 923, 924).
The large intestine extends from the termination of the ileum to the anus. It
is about five feet or more in length, being one-fifth of the whole extent of the
SACCULATIONS
APPENDICES EPIPIOICAE
FIG. 923. — Large intestine. A piece of transverse colon from a child two years old. The three chief charac-
teristics of the large intestine — sacculation, taeniae, and appendices epiploicae — are shown. (Cunningham.)
MUSCULAR BAND
intestinal canal. It is largest at its com-
mencement at the caecum, and gradually
diminishes as far as the rectum, where
there is a dilatation of considerable size
just above the anus. The diameter of the
distended caecum is usually about three
inches; the diameter of the descending
colon is about one and one-half inches.
The large intestine differs from the small
intestine in its greater size, its more
fixed position, its sacculated form (Figs.
923 and 924), and in possessing certain ap-
pendages to its external coat, the appendices
epiploicae (Fig. 924). The appendices
. I . • I I .
epiploicae are peritoneal pOUCheS COn- characteristic features of its structures.
taining fat, unless the subject is greatly
wasted; they protrude here and there from the peritoneal coat of the entire large
bowel, except the rectum, and are particularly frequent along the anterior longi-
MUSCULAR
BAND
MUSCULAR
BAND
FIG. 924. — Segment of large intestine, showing the
(Testut.)
1308
THE ORGANS OF DIGESTION
tudinal band. Further, the longitudinal muscular fibres of the large intestine do
not form a continuous layer around the gut, but are arranged in three longitudinal
bands or taeniae (taeniae coli] (Fig. 924). The large intestine, in its course, describes
an arch, which surrounds the convolutions of the small intestine. It commences
in the right inguinal region, in a dilated part, the caecum. It ascends through the
right lumbar and right hypochondriac regions to the under surface of the liver;
it here takes a bend to the left, the hepatic flexure, and passes transversely across
the abdomen on the confines of the epigastric and umbilical regions, to the left
hypochondriac region; it then bends again, the splenic flexure, and descends
through the left lumbar region to the left iliac fossa, where it becomes convoluted,
and forms the sigmoid flexure; finally it enters the pelvis, and descends along its
posterior wall to the anus. The large intestine is divided into the caecum, colon,
and rectum.
The Caecum (Intestinum Caecum) (Figs. 925, 926).
The caecum, the commencement of the large intestine, is the large blind pouch,
or cul-de-sac, situated below the ileo-caecal valve. Its name is derived from
caecus, blind. Its blind end or fundus is directed downward, and its open end
upward, communicating directly with the
colon, of which this blind pouch appears to
be the beginning or head, and hence the old
name caput caecum coli was applied to it.
An incomplete groove marks the upper limit
of the caecum. This groove is at the level
of the opening of the ileum. When the
caecum is contracted it bends on this groove
as on a hinge and forms an angle with the
ascending colon. In the contracted caecum
sacculations are but slightly evident; in the
distended caequm they are definite. Its size
is variously estimated by different authors,
but on an average it may be said to be two
and a half inches in length and three in
breadth. In 435 careful autopsies, Robinson
found the caecum and appendix congenitally
absent in one case.1 Sometimes a very large,
sometimes an exceedingly small, caecum is
encountered. A large caecum may be four
inches in width, entirely surrounded by peri-
toneum and usually is excessively mobile.
An adult caecum may be only one inch in
width and one-half an inch in length, and it
Js usually devoid of mobility. It is situated in the right iliac fossa, above the outer
^ialf of Poupart's ligament, usually rests on the Ilio-psoas muscle, the iliac fascia
intervening, and lies immediately behind the abdominal wall. The right side of
the caecum is in contact with the outer wall of the abdomen, and the outer aspect
of the anterior wall of the caecum is in contact with the anterior abdominal wall
(Spalteholz). When the caecum is full the small intestine lies in front of the left
side and lower portion of the anterior caecal wall. If the caecum is empty the
small intestine lies in front of its anterior wall, and the lower end is on a higher
ievel than when this portion of the gut is full. In a small per cent, of cases the
FIG. 925. — The caecum and colon laid open
to show the ileo-caecal valve.
1 St. Louis Courier of Medicine, October-December, 1902.
THE CAECUM 1309
caecum is covered by the omentum. Robinson describes four positions of the
caecum: 1. On the Psoas muscle. 2. To the right of the Psoas muscle. 3. In the
pelvis. 4. The potential position, in which it lies free in the abdominal cavity.
It may be found in various positions in the abdomen, because of elongation of
the fixation apparatus. The commonest position is on the Psoas muscle, and
this position is even more common in men than in women. It is twice as often in
the pelvis in women as in men — 20 per cent, of cases in the former; 10 per cent,
in the latter. As a rule, it is entirely enveloped on all sides by peritoneum, but in
a certain number of cases (6 per cent., according to Berry) the peritoneal cover-
ing is not complete, so that a small portion of the upper end of the posterior surface
is uncovered and connected to the iliac fascia by connective tissue. As a matter
of fact, there is no real mesocaecum— meaning by the term a peritoneal fold which
holds the caecum to the dorsal wall of the abdomen — except when there is failure
in development. Originally the caecum receives its blood along a single peri-
toneal fold, the ileo-caecal fold, which is a simple mesentery. As development
advances, this simple mesentery becomes a double fold and practically bloodless,
and is replaced by two vascular folds, the mesoappendix to the left and the mesen-
terico-colicum to the right. The mobility of the caecum varies. Very small caeca
are fixed. In most cases the caecum lies quite free in the abdominal cavity and
enjoys a considerable amount of movement. Sometimes it is excessively mobile,
and in such cases is usually also of large size. Such mobility is due to a stretched
fixation apparatus. A very large and mobile caecum may be made to come in
contact with any abdominal viscus and may enter any hernial sac on either side.
It is to be remembered that a mobile caecum carrying with it the appendix may
pass to almost any region of the abdomen. Sometimes the caecum fails to descend
or only descends a part of the way during development, the axial rotation of the
intestinal tract having been arrested. In such a case it may terminate at the
level of the gall-bladder, and the ascending colon is absent. In 310 adult males
Robinson found 8 per cent, with undescended caecum and appendix. Non-
descent is found in less than 4 per cent, of adult females. A partly descended
caecum usually lies upon the right kidney.
The caecum varies in shape, but, according to Treves, in man it may be classified
under one of four types (Fig. 926). In early foetal life it is short, conical, and
broad at the base, with its apex turned upward and inward toward the ileo-caecal
junction. It then resembles the caecum of some of the monkey tribe, e. g., Man-
gabey monkey. As the foetus grows the caecum increases in length more than in
breadth, so that it forms a longer tube than in the primitive form and without the
broad base, but with the same inclination inward of the apex toward the ileo-
caecal junction. This form is seen in others of the monkey tribe, e. g., the spider
monkey. As development goes on, the lower part of the tube ceases to grow and
the upper part becomes greatly increased, so that at birth there is a narrow tube,
the vermiform appendix, hanging from a conical projection, the caecum. This is
the infantile form, and as it persists throughout life, in about 2 per cent, of
cases, it is regarded by Treves as the first of his four types of human caeca. The
caecum is conical and the appendix rises from its apex. The three longitudinal
bands start from the appendix and are equidistant from each other. In the second
type, the conical caecum has become quadrate by the growing out of a saccule on
either side of the anterior longitudinal band. These saccules are of equal size,
and the appendix arises from between them, instead of from the apex of a cone.
This type is found in about 3 per cent, of cases. The third type is the normal type
of man. Here the two saccules, which in the second type were uniform, have
grown at unequal rates: the right with greater rapidity than the left. In conse-
quence of this an apparently new apex has been formed by the growing downward
of the right saccule, and the original apex, with the appendix attached, is pushed
1310
1 HE ORGANS OF DIGESTION
over to the left toward the ileo-caecal junction. The three longitudinal bands still
start from the base of the appendix, but they are now no longer equidistant from
each other, because the right saccule has grown between the anterior and postero-
external bands, pushing them over to the left. This type occurs in about 90 per
cent, of cases. The fourth type is merely an exaggerated condition of the third;
FIG. 926. — The four types of caecum.
the right saccule is still larger, and at the same time the left saccule has been
atrophied, so that the original apex of the caecum, with the appendix, is close to
the ileo-caecal junction, and the anterior band courses inward to the same situa-
tion. This type is present in about 4 per cent, of cases.
Supports of the Caecum. — According to Robinson,1 the caecum is maintained
in position by the mesocolon and a peritoneal fold, the right phrenico-colic liga-
ment, which arises from the hepato-duodenal and hepato-renal ligaments. It receives
support from the connective tissue about vessels and nerves, and inconstantly
from folds which fixes it in the iliac fossa and in the region of the precava.
The Interior of the Caecum. — In the interior of the caecum are seen depressions
which correspond to the surface haustra, and semilunar folds (plicae semilunares
coli) (Fig. 925), which correspond to the transverse surface constrictions. There
are three openings in the caecum: that into the colon; that into the ileum, which
is guarded by the ileo-caecal valve (p. 1315) ; and that into the appendix, which
may be guarded by the valve of Gerlach.
1 St. Louis Courier of Medicine, October-December, 1902.
THE CAECUM 1311
Pericaecal Folds and Fossae. — See p. 1272, and Figs. 879, 880, and 881.
The Vermiform Appendix (processm vermiformis) (Figs. 879, 880, 881 , 926, 927,
928, 929, and 931). — The vermiform appendix is found only in man, the higher
apes, and the wombat, although in certain rodents a somewhat similar arrangement
exists. In carnivorous animals the caecum is very slightly developed; in her-
bivorous animals (with a simple stomach) it is, as a rule, extremely large. It has
been suggested that the vermiform process in man is the degenerated remains of the
herbivorous caecum, which has been replaced by the carnivorous form.1 The
vermiform appendix is a long, narrow, worm-shaped, musculo-membranous tube,
which starts from what was originally the apex of the caecum. After development
has advanced the vermiform appendix comes off, as a rule, from the inner side of
the posterior wall of the caecum that is below and behind the termination of the
ileum. This origin usually corresponds to McBurney's point, which is in the
abdominal wall, midway between the umbilicus and the anterior superior iliac
spine, and which is the usual seat of the greatest tenderness in appendicitis. The
origin of the appendix varies with the type of caecum present. These variations
are shown in Fig. 926. In the foetal or infantile type of appendix it arises from
the apex of the caecum; in the second type of caecum it arises between the two
caecal sacculi ; in the third type it arises between a large outer and a small inner sac-
culus; and on the posterior wall of the caecum, the excessive growth of the anterior
wall having caused the appendix to originate posteriorly; in the fourth type there is
no internal sacculus, and the appendix arises from the posterior caecal wall behind
the ileo-caecal junction (p. 1310). The movable portion of the appendix may be
met with in different situations. It may pass upward and in front of the caecum
and colon, upward and behind the caecum, and even behind the colon between the
two layers of the mesocolon; upward and to the inner side, or upward, and to the
outer side of the caecum and colon. It may pass to the left under the ileum and
mesentery, upward and to the left or downward and to the left into the true pelvis.
It may pass directly downward under the caecum. It may pass to the right in
front of or back of the caecum. It may occupy any one of the caecal fossae (p. 1272),
but most often enters the ileo-caecal fossa. In unusual cases the appendix is found
in the inguinal canal as a portion of or the sole contents of a hernia; adherent to
the parietal peritoneum in front of or to the side of the caecum, or "behind the
peritoneum, below the caecum, adherent to the under surface of the caecum and in
contact with its muscular wall and covered by its peritoneal coat."2 When the cae-
cum is mobile the appendix may be found almost anywhere within the abdomen.
When the caecum is undescended, the appendix of course shares in the failure to
descend, and may be below the gall-bladder or in front of the right kidney, and may
pass in several directions: upward behind the caecum; to the left behind the ileum
and mesentery; or downward and inward into the true pelvis. It varies from one-
half an inch to nine inches in length, its average being about three inches. Its diam-
eter is from one-eighth inch to one-quarter inch. The operating surgeon may
occasionally fail to find an appendix buried in one of the caecal fossae, and may con-
clude that the diverticulum is absent. As a matter of fact, unless the colon is also
absent, it seems doubtful if the appendix is ever absent, except as a result of dis-
ease. This view is maintained by Lockwood and Rolleston,3 by Kelynack,4 and
others. It is asserted by some that the appendix is absent 5 times out of 10,000
autopsies. It is retained in position by a fold of peritoneum derived from the left
leaf of the mesentery, which forms a mesentery for it, and is called the meso-
appendix (p. 1269, and Figs. 879, 880, and 881). In color the healthy appendix is
1 Cunningham's Text-book of Anatomy.
2 Deaveps Surgical Anatomy.
3 Journal of Anatomy and Physiology, 1891, vol. xxvi.
4 A Contribution to the Pathology of the Vermiform Appendix.
1312 THE ORGANS OF DIGESTION
yellowish-pink, is soft and smooth to the touch, and the " subperitoneal vessels
are barely visible."1 The canal of the appendix is small and extends throughout
the whole length of the tube. The walls of the healthy diverticulum are thick,
and the diameter of the lumen is usually trivial as compared with the diameter of
the appendix itself. The lumen of the appendix communicates with the caecum
by an orifice which is placed below and behind the ileo-caecal opening (Fig. 932).
It is sometimes guarded above and to the left side by a semilunar fold of mucous
membrane, the valve of Gerlach (valvula processus vermiformis) . The valve is
inconstant, and is never perfect. It is stated that the appendix tends to undergo
obliteration as an involution change in a functionless organ. The lumen rarely
contains foreign bodies after death, but often contains fecal concretions. Certain
it is that in 25 per cent, of necropsies upon adults or elderly people the lumen
is found to be partially or completely occluded.
ILEOCOLIC ARTtRY
ANTERIOR ILEO-
CAECAL ARTERY
ANTERIOR CAECAL
ARTERY
APPENDICULAR
ARTERY
APPENDIX
VERMIFORMIS
FIG. 927. — Arteries of the csecum and of the appendix vermiformis and of the terminal portion of the ileum.
(Poirier and Charpy.)
Structure of the Appendix (Fig. 930). — The coats of the appendix correspond to
the coats of the bowel: serous, muscular (the outer layer of longitudinal, the inner
of circular fibres), submucous, and mucous. In the deepest portion of the mucous
coat, against the submucous coat, are the unstriated fibres constituting the mus-
cularis mucosae. The muscularis mucosae is often present in some regions and
absent in others. It may not be present at all.
The Outer or Serous Coat usually completely covers the appendix and has a
definite mesentery, the mesoappendix (p. 1269). Occasionally the base of the
appendix is not surrounded by peritoneum, but is extraperitoneal, lying in the
retroperitoneal tissue. The appendiculo -ovarian ligament of Olado is occasionally
present in females. It is a prolongation of the mesoappendix which passes into
the broad ligament, and is extremely thin, and its fine connective-tissue fibres
send prolongations into the longitudinal muscle-fibres of the appendix. Lock-
wood points out that the subperitoneal tissue of the meso-appendix and "the
blood-vessels, nerves, and lymphatics which it contains are very intimately con-
nected with the submucosa. This union takes place at certain large gaps in the
muscular coats. These gaps serve for the transmission of blood-vessels, nerves,
and lymphatics from the mesoappendix to the mucous coat. They are situated
at the junction of the mesoappendix with the appendix."2
The Longitudinal Muscular Layer is thin and irregularly distributed, and in certain
regions may be excessively thin or actually absent, and between the fibres are the
blood-vessels, nerves, and lymphatics passing from the subperitoneal tissue to the
mucous coat.
1 Appendicitis, its Pathology and Surgery. By Charles Barrett Lockwood.
2 Ibid.
THE CAECUM
1313
The Circular Fibres are much better developed than the longitudinal fibres, and,
according to Ix)ckwood, the layer is 1 mm. thick. Large gaps are found here and
there for the passage of vessels, lymphatics, and nerves to and from the meso-
appendix and the mucous membrane, and a few vessels pierce the fibres at
other points (Lockwood).
The Submucous Coat varies greatly in thickness. It contains blood-vessels,
nerves, and lymphatics, and some lymphoid follicles.
The Mucous Membrane (Fig. 928) is covered by columnar
epithelial cells and contains numerous solitary lymph-
follicles, some glands of Lieberkiihn, surrounded by
lymphoid tissue, blood-vessels, lymphatics, and nerves.
The muscularis mucosae may be absent, may be scanty,
or may be distinct. The lymphoid follicles are visible to
the naked eye (Fig. 928). Some of them are in the sub-
mucosa, some of them chiefly in the mucosa, the bases of
the latter, however, being in the submucosa. Lockwood
estimates that an appendix three and a half inches in
length contains from 150 to 200 follicles.
Blood-vessels of the Caecum and Appendix (Figs. 927, 929,
945, and 946). — The ileo-colic artery in the ileo-colic angle
gives off the anterior and posterior ileo-caecal arteries. The
anterior ileo-caecal runs down over the front of the ileum
and supplies the ileum, and sends off a terminal branch,
the anterior caecal artery, which supplies the anterior surface
of the caecum and of a portion of the ascending colon, and
to the upper and lower margins of the ileo-caecal valve. It
sends no branch to the appendix. The arteries of the ap-
pendix come from the posterior ileo-caecal artery. Tins
vessel, after arising from the ileo-colic artery, passes back
of the termination of the ileum and gives branches to the face'of the~ermiformnappen-
lower end of the ileum back of a portion of the ascending dix- <Bonamy and Broca->
colon and to the lower margin of the ileo-caecal valve,
where they anastomose with the valvular branches from the anterior ileo-caecal
(Lockwood). From the posterior ileo-caecal comes the posterior caecal branch,
which passes over the posterior and inner portion of the caecum near the base
of the appendix and sends one or two branches to the appendix. The chief blood-
supply of the appendix is the appendicular artery, which comes off the beginning
of the posterior ileo-caecal or, occasionally, from the termination of the ileo-colic.
If there is a distinct mesoappendix the largest branch of the artery passes along
its free edge. If the mesoappendix is absent or rudimentary the artery usually
lies upon the appendix from base to tip beneath the peritoneum.
Lockwood points out that the appendicular artery as it enters the mesoappen-
dix divides into three branches. The largest branch runs along the free edge,
and from this the tip of the appendix obtains its blood-supply; "the other two
reach the appendix at intervals of half an inch."1 When the branches reach
the appendix they divide and pass around it in the subperitoneal coat and send
branches through the muscular gaps to enter and pass through the submucous
coat.
In females there is occasionally some additional blood-supply through a branch
of the ovarian artery in the appendiculo-ovarian ligament.
The veins of the appendix are numerous, thin walled, and large. Veins from
the submucous plexus pass through the muscular gaps and enter the subperi-
1 Appendicitis, its Pathology and Surgery. By Charles Barrett Lockwood.
83
1314
THE ORGANS OF DIGESTION
toneal plexus. Veins from the subperitoneal plexus pass into veins in the meso-
appendix which correspond to but do not really accompany the arteries (Lock-
wood). Most of the veins of the mesoappendix pass to the posterior ileo-caecal
vein, though some pass directly to the caecal vein. These veins are radicles of
the portal system.
ILEOCOLIC ARTERY
AND VEIN
POSTERIOR
ILEOCAECAL
ARTERY
AND VEIN
ILEAC BRANCH
APPENDICULAR
ARTERY AND
VEIN
ASCENDING
COLON
FIG. 929. — Arteries and veins of the csecum and vermiform appendix seen from behind. (Poirier and Charpy.)
Lymphatic System of the Caecum and Appendix (Fig. 930). — Surrounding the base
of each lymph-follicle in the submucous tissue of the appendix is a lymph-space,
which Lockwood calls the follicular or basilar lymph-sinus. This sinus communi-
cates with the lymphatics of the submucous coat, "which again communicate
freely through the hiatus muscularis with those of the peritoneum and of the
mesoappendix."1 The collecting trunks from the caecum and appendix follow the
EPITHELIUM
MUSCULAR LAYER
FIG. 930. — Transverse section of the vermiform appendix of man. (Kolliker.)
blood-vessels (Fig. 931). The anterior collecting trunks of the caecum pass
through several small glands in the anterior ileo-caecal fold, and terminate in
glands along the ileo-colic artery (Fig. 931). The posterior collecting trunks
pass through some small glands and terminate in glands along the ileo-colic
artery. The appendicular collecting trunks enter the mesoappendix. There are
usually four of them, sometimes five. Some of them traverse a gland constantly
present at the ileo-caecal angle (Clado). Another gland is constant. It is situated
beneath the ileo-colic fossa (Lockwood and Rolleston). The editor subscribes to
1 Appendicitis, its Pathology and Surgery. By Charles Barrett Lockwood.
THE CAECUM
1315
Lockwood's statement that in appendicitis there is often a chain of inflamed
glands along the inner side of the ascending colon behind the ascending meso-
colon. Hence this is one road taken by the lymphatics of the appendix. The
others pass to the mesenteric glands.
ANTERIOR
LYMPHATICS
OF C/ECUM
FIG. 931. — Lymphatics of the caecum and appendix, anterior view. (Pofrier and Charpy.)
The Heo-caecal Valve or the Valve of Bauhin (valvuli coli) (Figs. 932, 933,
934, and 935). — The lower end of the ileum terminates by opening into the inner
and back part of the large intestine, at the point
of junction of the caecum with the colon. The
opening is guarded by a valve, consisting of
two semilunar segments, an upper or colic seg-
ment (labium superius) and a lower or caecal
ORIFICE O
APPEND
FIG. 932. — Ileo-caecal valve of the circular type.
(Poirier.)
FIG. 933. — Vertical section through the caecum
and ileo-caecal valve. (Gegenbaur.)
segment (labium inferius), which project into the lumen of the large intestine.
The upper one, nearly horizontal in direction, is attached by its convex border to
1316
THE ORGANS OF DIGESTION
the point of junction of the ileum with the colon ; the lower segment which is more
concave and longer, is attached to the point of junction of the ileum with the
caecum. At each end of the aperture the two segments of the valve coalesce, and
are continued as a narrow membranous ridge around the canal for a short distance.
Each ridge is known as the
retinaculum or frenulum of
the valve (frenulum valvulae
coli}. The left or ante-
rior end of the aperture is
rounded; the right or poste-
rior is narrow and pointed.
In the formation of the valve
the termination of the small
intestine invaginates for a
short distance into the lumen
of the large intestine (Fig.
933), the invaginated portion
of the wall of the small intes-
SACCULUS
SUPERIOR J
SEGMENT— £
INFERIOR
SEGMEN
ILEUM'
LONG MUSCU-
LAR FIBRES
FROM ILEUM
ANTERIOR
TXENIA
POSTERIOR
CUL-DE-SAC
OF C/ECUIV
FIG. 934. — Caecum and vermiform appendix. (Sappey.)
tine uniting with a corres-
ponding portion of the wall
of the large intestine.
Each segment of the valve
is formed by a reduplication
of the mucous membrane and of the circular muscular fibres of the intestine, the
longitudinal fibres and peritoneum being continued uninterruptedly across from
one portion of the intestine to the other. When the longitudinal fibres and peri-
toneum are divided or removed, the ileum may be drawn outward, and all traces
of the valve will be lost, the ileum appearing to open into the large intestine by a
funnel-shaped orifice of large size.
The surface of each segment of the valve directed toward the ileum possesses
villi, and presents the characteristic structure of the mucous membrane of the
small intestine; while that turned
toward the large intestine is desti-
tute of villi, and marked with the
orifices of the numerous tubular
glands peculiar to the mucous
membrane of the large intestine.
These differences in structure con-
tinue as far as the free margins of
the valve. When the caecum is
distended it is supposed that the
margins of the opening are approxi-
mated so as to prevent reflux into
the ileum. It is known, however,
that a very large enema which dis-
tends the caecum and colon may in
part enter the ileum, being driven
there by waves of reversed peris-
talsis. The valve resists, but a
certain amount of pressure over-
comes it. Some believe that the so-called ileo-caecal valve is not a valve, but a
distinct sphincter. This has been demonstrated to be true in cats and dogs, but
lacks demonstration in man (p. 1331).
ANTERIOR
T/EN IA
EDGE OF
CJCCUM
SUPERIOR
SEGMENT
POSTERIOR
T/E N I A'
NTERNAL
T/ENIA
ORIFICE OF
VALVE
INFERIOR
SEGMENT
FIG. 935. — Ileo-caecal valve. (Sappey.)
THE COLON 1317
The Colon.
The colon is divided into four parts — the ascending, transverse and descending
colon, and the sigmoid flexure.
The Ascending Colon (colon ascendens}. — The ascending colon is smaller than
the caecum, with which it is continuous. It passes upward, from its commence-
ment at the frenula of the caecum, opposite the ileo-caecal valve, to the under sur-
face of the right lobe of the liver, on the right of the gall-bladder, where it is lodged
in a shallow depression on the liver, the impressio colica; here it bends abruptly
inward to the left, forming the hepatic flexure (flexura call dextra). It is retained
in contact with the posterior wall of the abdomen by the peritoneum, which covers
its anterior surface and sides, its posterior surface being connected by loose areolar
tissue with the Quadratus lumborum and Transversalis muscles, and with the
front of the lower and outer part of the right kidney (Fig. 936). Sometimes the
peritoneum almost completely invests it, and forms a distinct but short meso-
colon1 (p. 1269). It is in relation, in front, with the convolutions of the ileum and
the abdominal parietes.
The Transverse Colon (colon transversum) (Fig. 871). — The transverse colon,
the longest part of the large intestine, passes transversely from right to left across
the abdomen, opposite the confines of the epigastric and umbilical zones, into the
left hypochondriac region, where it curves downward beneath the lower end of
the spleen, forming the splenic flexure (flexura coli sinistra). In its course the
transverse colon describes an arch, the concavity of which is directed backward
toward the vertebral column and a little upward; hence the name transverse arch
of the colon. This is the most movable part of the colon, being almost completely
invested by peritoneum, and connected to the spine behind by a large and wide
duplicature of that membrane, the transverse mesocolon (Fig. 876). The trans-
verse colon is in relation, by its upper surface with the liver and gall-bladder, the
great curvature of the'stomach, and the lower end of the spleen; by its under sur-
face, with the small intestines; by its anterior surface, with the anterior layers
of the great omentum and the abdominal parietes; its posterior surface on the
right side is in relation with the second portion of the duodenum, and on the left
side is in contact with some of the convolutions of the jejunum and ileum.
The Descending Colon (colon descendens). — The descending colon passes
downward through the left hypochondriac and lumbar regions along the outer
border of the left kidney. At the lower end of the kidney it turns inward toward
the outer border of the Psoas muscle, along which it descends to the crest of the
ilium, where it terminates in the sigmoid flexure. At its commencement it is con-
nected with the Diaphragm by a fold of peritoneum, the phreno-colic ligament
(see p. 1268). It is retained in position by the peritoneum, which covers its
anterior surface and sides, its posterior surface being connected by areolar tissue
with the outer border of the left kidney, and the Quadratus lumborum and
Transversalis muscles (Fig. 876). It is smaller in calibre and more deeply placed
than the ascending colon, and is more frequently covered with peritoneum on its
posterior surface than the ascending colon (Treves).
The Sigmoid Flexure, Pelvic Colon or Sigmoid Colon (colon sigmoideum)
(Figs. 937, 938, 939, and 940) is the narrowest part of the colon; it is situated in
the left iliac fossa, commencing from the termination of the descending colon, at
the margin of the crest of the ilium, and then forming a loop, which varies in length
_! Treves states that after a careful examination of one hundred subjects, he found that in fifty-two there was
neither an ascending nor a descending mesocolon. In twenty-two there was a descending mesocolon, but no
trace of a corresponding fold on the other side. In fourteen subjects there was a mesocolon to both the ascend-
ing and the descending segments of the bowel ; while in the remaining twelve there was an ascending mesocolon,
but no corresponding fold on the left side. It follows, therefore, that in performing lumbar colostomy a meso-
colon may be expected on the left side in 36 per cent, of all cases, and on the right in 26 per cent. (The Anat-
omy of the Intestinal Canal and Peritoneum in Man, 1885, p. 55.) — ED. of 15th English edition.
1318
THE ORGANS OF DIGESTION
and position, and which terminates in the rectum at the level of the attachment of
the mesentery upon the front of the third sacral vertebra. It passes downward
Anterior
1 n f
lamella OJ
lumbar fascia.
Posterior
Middle lamella of
lamella of iumoa ,. fascia.
lumbar
FIG. 936. — Diagram of the relations of the large intestine and kidneys, from behind.
about two inches parallel to the outer border of the Psoas muscle, then taking a
transverse direction enters the cavity of the pelvis, crosses this cavity from left to
right and a little upward to the lower margin of the right iliac fossa; "from this
THE COLON
1319
DESCENDING COLON
point it passes downward, backward, and inward along the anterior surface of the
sacrum to its junction with the rectum."1 It is surrounded with the peritoneum
and is attached to the posterior abdominal wall by
the mesosigmoid, a continuation of the mesocolon,
but which greatly exceeds the latter in length, hence
the sigmoid is the most mobile portion of the large
intestine. Tuttle divides the sigmoid into four por-
tions. The first or vertical portion; the second or
transverse portion; the third portion, which is a loop
and is concave upward if the sigmoid occupies the
pelvis, and is concave downward if it occupies the
abdomen ; the fourth portion, which is curved irregu-
larly in the hollow of the sacrum, and which joins
the rectum as often from the right as from the left.
WThen the sigmoid is lifted up and to the right and
the mesosigmoid is put slightly upon the stretch, an
opening is seen at the parietal border of the left
FIG. 938. — Sigmoid colon and rectum, front view. The broken lines indicate the situation of the concealed part
of'the sigmoid colon. The small intestine is drawn away, and the anus is turned forward. (Testut.)
layer of the mesosigmoid. This opening leads into a cul-de-sac, the intersigmoid
fossa. When the sigmoid is empty most of it falls into the recto-vesical or recto-
1 Tuttle, Diseases of the Anus, Rectum, and Pelvic Colon.
1320
THE ORGANS OF DIGESTION
vaginal space (Fig. 938). When distended it mounts up into the abdomen, reaching
to or even above the umbilicus. The sigmoid flexure is in relation in front with
the small intestine and abdominal parietes. The sigmoid mesocolon is attached
to a line running downward and inward from the crest of the ilium, across the
Psoas muscle (Fig. 876).
The Rectum (Intestinum Rectum) (Figs. 937, 938, 939, 940, 941, 942).
The rectum is the terminal part of the large intestine, and extends from the
termination of the sigmoid flexure to the level of the semilunar valves of Mor-
PROSTATE
TRANSVERSE
PERINJEI
MUSCLE
EXTERNAL
SPHINCTER
MUSCLE
FIG. 939.— Sagittal section in the median line of the pelvis. (Poirier and Charpy.)
gagni. The sigmoid flexure terminates at the level of the attachment of the
mesentery in front of the third sacral vertebra. This definition is practical and
useful. It was suggested by Sir Frederick Treves. " It gives to the organ
definite limits; it separates the mobile from the immobile portion of the gut; it
marks the line where the course of the blood-supply changes; it indicates the
point where the three longitudinal muscular bands of the colon spread out and
become more or less equally distributed arcund the gut; and, finally, it marks a
point at which there is always a decided narrowing in calibre, indicating the
juncture of the rectum with the pelvic colon."1 The old division added to this
the so-called first part of the rectum, which we consider as part of the sigmoid colon.
The rectum is divided into two portions, a superior and an inferior. The supe-
rior or sacrococcygeal portion of the rectum (ftexura sacralis) curves downward
with the concavity forward and upward in front of the sacrum and coccyx, and
1 A Treatise on Diseases of the Anus, Rectum, and Pelvic Colon. By James P. Tuttle.
THE RECTUM
1321
is continued as far as the apex of the prostate gland, about an inch in front of
the tip c? the coccyx. The inferior or prostatic portion (flexura perinealis) begins
at this point. The bowel is directed downward and backward, being convex in
front, and terminates at the beginning of the anus at the level of the semilunar
valves of Morgagni. The inferior or prostatic portion of the rectum is described
by Symington as the anal canal.
HECTAL FOLD
VESICO-UTERINt
CUL-DE-SAC
CUL-DE-SAC
OF. DOUGLAS \v'/\
FIG. 940. — Median sagittal section of the female pelvis. (Luschka.)
Curves of the Rectum. — It will be seen, therefore, that the rectum presents two
antero-posterior curves: the first, with its convexity backward, is due to the con-
formation of the sacro-coccygeal column, and represents the arc of a circle, the
centre of which is opposite the third sacral vertebra. The lower one has its
convexity forward, and is angular. Its centre corresponds to a line drawn
between the anterior parts of the ischial tuberosities. Two lateral curves are also
described: the one to the right, opposite the junction of the third and fourth sacral
vertebrae; the other to the left, opposite the sacro-coccygeal articulation. They
are of little importance.
The adult rectum as here described has a length of from four to six inches in men,
and from three and five-eighths to five and one-eighth inches in women. Accord-
ing to Tuttle the length of the rectum depends to some degree on the size of the
subject, and is some what greater in the old than in the young. The prostatic portion
is the narrowest portion of the rectum. The widest part of the rectum is the ampulla
recti just above the anal canal (Figs. 939 and 940). The prostatic portion has no
peritoneal investment whatever and includes the lower two inches of the superior
portion of the rectum. When the rectum is empty it is a mere slit, the anterior and
posterior walls being in contact. When distended it is "irregularly cylindrical"
(Tuttle). At and above the level of the third sacral vertebra the gut is entirely sur-
rounded by peritoneum, and there is a mesosigmoid. This is the mesorectum of
those who describe the lower pelvic colon as the first part of the rectum. At the level
1322
THE ORGANS OF DIGESTION
FIG. 941. — Diagram of rectum, showing Hous-
ton's valves in the interior. (Cunningham.)
of the third sacral vertebra the true rectum
begins, and the true rectum has no meso-
rectum. The rectum is covered in front and
laterally by peritoneum at its upper part ;
gradually the peritoneum leaves its sides,
and about an inch above the prostate is re-
flected from the anterior surface of the bowel
on to the posterior wall of the bladder in
the male, and the upper fifth of the posterior
wall of the vagina in the female, forming
the recto-vesical or recto-vaginal pouch (ex-
cavatio redovesicalis and excavatio redoute-
rina), as the case may be (Fig. 866). The
balance of the rectum has no peritoneal cov-
ering. The level at which the peritoneum
leaves the anterior wall of the rectum to be
reflected on to the viscus in front of it is of
considerable importance from a surgical
point of view, in connection with removal of the lower part of the rectum. It is
higher in the male than in the female. In the former the height of the recto-
vesical pouch is about three inches; that is to say, the height to which an ordinary
index finger can reach from the anus. In the female the height of the recto-
vaginal pouch is about two and a quarter inches from the anal orifice.
The upper or sacro-coccygeal portion of the rectum is in relation, in front, in
the male, with the recto-vesical pouch, the triangular portion of the base of the
bladder, the vesiculae seminales, and vasa deferentia, and more anteriorly with
the under surface of the prostate. In the female, with the posterior wall of the
vagina below, and the recto-vaginal pouch above, in which are some convolutions
of the small intestine (Fig. 940). To the sides below the peritoneal reflections,
the rectum is surrounded by cellular tissue in which on each side lie the lateral
sacral artery and the bifurcated hypogastric plexus. This portion of the rectum is
separated from the sacrum and coccyx by an interval, the retro-rectal space, which
is filled with cellular tissue. The superior portion of the distended rectum is in con-
tact posteriorly and on each side with the sacral plexus, ganglia of the sympathetic,
and the fascial origin of the pyramidalis muscle (Tuttle). The lower or prostatic
portion in men is in relation anteriorly with the prostate gland and the membranous
urethra; in women with the posterior wall of the vagina. The lower end of the
rectum takes a backward turn, and the uro-genital organs turn forward; the inter-
vening space is called the perineum. In tlie female, the fibro-fatty and muscular
tissue which occupies this space is called the perineal body. The prostatic portion
of the rectum is invested by the Internal sphincter, supported by the Levatores
ani muscles, and surrounded at its termination by the External sphincter; in the
empty condition it presents the appearance of a longitudinal slit. Posteriorly
the lower part of the rectum is in contact with cellular tissue, which separates it
from the coccygeal gland and the coccyx.
Supports of the Rectum. — The rectum as it has been described in these pages is a
fixed tube. The upper portion of the rectum is supported by "the inferior mesen-
teric arteries and the fibrous sheaths which surround them" (Tuttle) ; by the peri-
toneal folds which attach it to the sacrum ; and by the peritoneal folds which pass
in front to the bladder (plicae rectovesicales) , or to the uterus (plicae redouterinae) ,
and laterally to the pelvis. The middle of the rectum receives some support
from the lateral sacral arteries and their fibrous sheaths. The lower portion of the
rectum is supported by the Levator ani, External sphincter, and Recto-coccygeus
muscles.
THE RECTUM
1323
Blood-vessels and Lymphatics of Rectum. — See pp. 1328 and 1329.
Nerves of Rectum. — See p. 1329.
Structure of Rectum. — See p. 1324.
RECTAL VALVES
A B C
FIG. 942. — The anal canal and lower part of the rectum in the foetus. A, aged four to five months ; B, six
months ; C, nine months. In each the anal canal is distinctly marked off from the rectum proper ; the columns
of Morgagni and the rectal valves are distinct. (Cunningham.)
The Common Anal Canal (pars analis recti) (Figs. 942 and 943).— The anal
canal is the third portion of the rectum of the older descriptions. It begins
where the true rectum ends. This canal is the portion of the intestinal tract which
LONGITUDINAL
FIBRES OF
RECTUM
PART OF
LEVATOR AN.
INTERNAL
SPHINCTER
ANAL CANAL
RUG/E OF
MUCOUS
MEMBRANE
COLUMNS OF
MORGAGNI
ANAL VALVES
FIG. 943.— The interior of the anal canal and lower part of the rectum, showing the columns of Morgagni and
the anal valves between their lower ends. The columns were more numerous in the specimen than usual.
(Cunningham.)
is below the distribution of genuine mucous membrane, and is just posterior to
the middle of a line drawn from one tuberosity to the other. It lies between the
true skin and the upper borders of the semilunar valves of Morgagni. When at
rest it is a mere slit placed antero-posteriorly. The external opening of the anal
canal is the anus. The skin about the anus is pigmented, is thrown into radi-
ating folds by the contraction of the External sphincter muscle, and contains
hairs, sebaceous glands, and sudoriparous glands (glandulae circumanales).
Ascending into the canal, it alters its character and becomes muco-cutaneous,
and true mucous membrane appears at the rectum proper. Back of the anus is
a median cutaneous fold passing posterior to the coccyx and called the anal raphe.
In front of the anus is a median fold which, in the female, passes forward and
merges with the labia major and in the male continues into the raphe" of the
scrotum. This is called the perineal raphe. The length of the anal canal is three-
quarters to one inch. "Its circumference varies from 3 cm. (one and three-
sixteenths inches) in normal condition to 15 cm. (five and five-sixteenths inches)
in disease, following injury or vicious practices. The average anus will admit a
cylinder of 65 mm. in circumference without rupturing the mucous membrane."1
1 Diseases of the Anus, Rectum, and Pelvic Colon. By James P. Tuttle.
1324 THE ORGANS OF DIGESTION
Relations of the Anal Canal. — It is surrounded by the external and internal
sphincter muscles, and above by the Levatorcs ani. To each side is the ischio-
rectal fossa containing fat. Between the anal canal and the coccyx is a collec-
tion of muscular fibres and connective tissue, the ano-coccygeal body of Symington.
In front, in the male, is the bulb of the urethra and the base of the triangular
ligament ; in the female, is the perineal body, which separates the anus from
the vagina. There are three layers in the wall of the anal canal:
1. The muco-cutaneous layer, which contains glands, blood-vessels, and numer-
erous nerve-endings. The lower portion is covered with pavement-epithelium,
but gradually there is a transition, and at the beginning of the rectum proper the
epithelium is entirely columnar. The valves of Morgagni, the anal valves or the semi-
lunar valves (Figs. 943 and 944) are in the upper portion of the anal canal between
the lower ends of the columns of Morgagni (Figs. 943 and 944). Above the valves
the canal is lined by transitional mucous membrane, below them by modified skin.
The ano-rectal line is not straight, but is irregularly dentated by trivial eleva-
tions, each of which is papilliform at its summit. According to Tuttle, these
elevations number from five to eight. About one-fifth of an inch below the ano-
rectal line is the depression known as Hilton's white line (annulus haemorrhoidalis)
(Fig. 944). This line is somewhat indistinct to sight, but can always be felt with
the finger. It marks the junction of the External with the Internal sphincter.
Above Hilton's line are some mucous crypts and also dilatations produced by the
internal haemorrhoidal plexus of veins (Fig. 944).
2. The fibro-cellular layer is beneath the mucous membrane. Above Hilton's
line it is composed of cellular tissue; below it is a thin fascia-like layer which joins
the superficial fascia.
The anal canal is surrounded by longitudinal fibres from the rectum, fibres from
the Levator ani, the lower portion of the Internal sphincter, and particularly by
the External sphincter.
Blood-vessels, Lymphatics, and Nerves of Anus. — See pp. 1328 and 1329.
Structure of Large Intestine (including the Rectum and Anal Canal). — The
large intestine has four coats — serous, muscular, areolar or submucous and mucous.
The Serous Coat (tunica serosa}. — The serous coat is derived from the peritoneum,
and invests the different portions of the large intestine to a variable extent. The
caecum is completely covered by the serous membrane, except in a small percent-
age of cases (5 or 6 per cent.), where a small portion of the upper end of the pos-
terior surface is uncovered. The ascending and descending colon are usually
covered only in front and at the sides ; a variable amount of the posterior surface
is uncovered. The transverse colon is almost completely invested, the parts corre-
sponding to the attachment of the great omentum and transverse mes~ocolon being
alone excepted. The sigmoid flexure is completely surrounded, except along the
line to which the sigmoid mesocolon is attached. The upper two-thirds of the
rectum is covered in front and laterally by the peritoneum, but not posteriorly,
between the two posterior folds of peritoneum, the so-called mesorectum; later
it is covered only on its anterior surface; and the lower portion is entirely
devoid of any serous covering. In the course of the colon the peritoneal coat is
thrown into a number of small pouches filled with fat, called appendices epiploicae.
They are chiefly appended to the transverse colon, and are particularly numerous
along the anterior band.
The Muscular Coat (tunica muscularis). — The muscular coat consists of an
external longitudinal and an internal circular layer of muscular fibres.
The Longitudinal Fibres, although found to a certain extent all around the
intestine, do not form a uniform layer over the whole surface of the large
intestine. In the caecum and colon they are especially collected into three flat
longitudinal bands or taeniae (taeniae coli) (Figs. 923 and 924), each being about
THE STRUCTURE OF THE LARGE INTESTINE 1325
half an inch in width. These bands commence at the base of the vermiform
appendix, which structure is surrounded by a uniform layer of longitudinal
muscular fibres. The bands pass from the base of the appendix to the rectum.
At this point they broaden, fuse, and surround the rectum. On the ascend-
ing, descending, and sigmoid colon the mesocolic band (taenia mesocolica) is
posterior and internal; the omental band (taenia omentalis) is posterior and
external; the free band (taenia libera) is anterior. On the transverse colon the
taenia libera is inferior; the taenia mesocolica is posterior; the taenia omentalis
is anterior and superior. These bands are one-sixth shorter than the other coats
of the intestine to which they are applied, and serve to produce the sacculi (Fig.
924) . which are characteristic of the caecum and colon ; accordingly, when they
are dissected off, the tube can be lengthened, and its sacculated character becomes
lost. The sacculations are called haustra coli. There are three rows of the sac-
culations separated from each other by the longitudinal bands. These pouches
are also subdivided by transverse furrows which correspond to concave folds of
mucous membrane, called semilunar folds (plicae semilunares coli). In the sig-
moid flexure the longitudinal fibres become more scattered; but upon its lower
part, and around the rectum, they spread out and form a layer which completely
encircles this portion of the gut, but is thicker on the anterior and posterior
surfaces, where two accentuations exist, than on the lateral surfaces. In the
rectum the external fibres of the longitudinal layer descend and are inserted into
the fascia covering the Levator ani muscle. The middle fibres are mingled with
descending fibres of the Levator ani and terminate by attachment to the rectal
wall. The internal fibres descend between the External and Internal sphincter
muscles and are inserted into the superficial fascia around the anal margin.
The lower part of the rectum is surrounded by the Levator ani muscle (p. 453).
In addition to the muscular fibres of the bowels, two bands of plain muscular
tissue are to be noted. They arise from the front of the second and third coccy-
geal vertebrae, and pass downward and forward to blend with the longitudinal
muscular fibres on the posterior wall of the rectum. Each is known as the recto-
coccygeal muscle (m. rectococcygeus) .
The Circular Fibres form a thin layer over the caecum and colon, being especially
accumulated in the intervals between the sacculi. In the rectum the circular fibres
constitute a thick coat at some portions of the circumference and a thinner coat
at others. The circular fibres are thickened at every flexure. The thickenings
only partly surround the gut, and hence are not to be considered as additional
sphincters. Tuttle calls them the semicircular muscles of the rectum. These semi-
circular muscles are opposite the insertion of Houston's valves. At the lower end
of the rectum the circular fibres become very numerous and constitute the Internal
sphincter muscle (m. sphincter ani intermis) (Fig. 943). Tuttle describes it as fol-
lows: "This muscle, composed of an aggregation of circular fibres, begins about
4 cm. above the anal margin, and gradually increases in thickness until it reaches
the ano-rectal line, after which it thins out again and disappears about the middle
of the anal canal. Its width from above downward averages 1 to 3 cm. (three-fifths
of an inch to one and one-fifth inches). Its thickness is so variable that no accurate
measurement can be given. Its lower fibres are below and within the grasp of the
External sphincter, from which it is separated by a narrow zone of connective
tissue. A depressed zone, not always perceptible to the eye, but appreciable
by digital touch, marks the line of division between these two muscles."1 The
Internal sphincter is an involuntary muscle. The external sphincter muscle is
not a portion of the wall of the bowel. It is described on pages 450 and 451.
The Areolar Coat or Submucous Coat (tela submucosa). — The areolar or sub-
mucous coat connects the muscular and mucous layers closely together. This coat
1 Diseases of the Anus, Rectum, and Pelvic Colon. By James P. Tuttle.
1326
THE ORGANS OF DIGESTION
is thicker, looser, and more elastic in the rectum than elsewhere. In this coat are
the blood-vessels, nerves, and lymphatics.
The Mucous Membrane (tunica mucosa). — The mucous membrane, in the caecum
and colon, is pale, smooth, destitute of villi, and raised into numerous crescentic
folds which correspond to the intervals between the sacculi. In the rectum it is
thicker, of a darker color, more vascular, and connected loosely to the muscular
coat, as in the oesophagus.
The rectum contains certain horizontal folds. Most of them disappear when
the gut is distended, but some of them do not disappear, but remain as distinct
MUCOUS
MEMBRANE
DILATATION
OF VEINS
COLUMNS OF
MORGAGNI
VALVE OF
MORGAGNI
HILTON'S
WHITE LINE
MUSCULAR WALL
OF RECTUM
INTERNAL HEMOR-
RHOIDAL PLEXUS
DILATATION
OF VEIN
COMMUNICATION BE-
TWEEN INTERNAL ANt
EXTERNAL HEMOR-
RHOIDAL PLEXUS
INTERNAL
SPHINCTER
EXTERNAL
SPHINCTER
LONGITUDINAL
TENDINOUS FIBRES
SUBCUTANEOUS
CELLULAR TISSUE
FIG. 944. — Inner wall of the lower end of the rectum and anus. On the right the mucous membrane has
been removed to show the dilatation of the veins and how ihey pass through the muscular wall to anastomose
with the external haemorrhoidal plexus. (Luschka.)
folds with free crescentic edges. These permanent folds were first described by
Houston, of Dublin, and are known as rectal valves or Houston's valves (plicae
transversales recti) (Figs. 941 and 942). Each fold surrounds more than one-
third of the gut, and is composed of mucous membrane, submucous tissue, and
a layer from the circular muscular layer of the gut. There may be three, four, or
five of these folds. Three of them are constant. One is on the right rectal wall,
about the point of peritoneal reflection; another is on the left side, about one
inch above the margin of the anal canal. A third is on the rectal wall, either
toward the right or left, at the point where the rectum joins the front of the
sigmoid. These shelf-like valves are not perfectly flat, for on the superior surface
of each is a depression.
The borders of a valve are thinner than its base and are very flexible. These
valves support the mass of faeces as it descends, and give to it a rotary motion
(Tuttle). In the lower end of the rectum the mucous membrane forms longi-
tudinal folds known as the columns of Morgagni or the rectal columns (columnae
rectales [Morgagni]) (Figs. 943 and 944). There are from five to ten of these
folds, each of which is about one-half an inch long, and they contain longitudinal
muscle-fibres. They are most prominent when the sphincter contracts. The base
of each column helps to form the upper margin of the anal canal. The outer angle
of each column below passes into a similunar valve. The grooves between the
columns are shallow above and deeper below, and end in the semilunar valves.
The semilunar valves, valves of Morgagni or anal valves (Figs. 943 and 944) are folds
which stretch from the base of one column to another, and form the anal pockets
or crypts of Morgagni (sinus rectales). These pockets are about 5 mm. in depth.
They are most marked pos'eriorly (Ball), but none exists in either the anterior
THE STRUCTURE OF THE LARGE INTE8TINE
1327
or posterior commissure (Tuttle). Below the sinuses is the white line of Hilton
(Fig. 944), which reaches to the region where hair and sebaceous glands appear.
As in the small intestine, the mucous membrane consists of a muscular layer, the
muscularis mucosae (Fig. 948); of a quantity of retiform tissue in which the vessels
ramify; of a basement-membrane and epithelium, which is of the columnar variety,
and exactly resembles the epithelium found in the small intestine. In the rectum
the epithelial cells are columnar; at the lower end of the tube, however, they begin
to change into stratified polyhedrons and prisms. The mucous membrane of the
large intestine presents for examination simple follicles and solitary glands.
The Simple Follicles, Intestinal Glands, Crypts or Glands of Lieberkuhn (glandulae
intestinales [Lieberkuhni]) (Fig. 948) are minute tubular prolongations of the
mucous membrane arranged perpendicularly, side by side, over its entire sur-
face; they are longer, more numerous, and are placed in much closer apposition
than those of the small intestine; and they open by minute rounded orifices upon
the surface, giving it a cribriform appearance.
, ,
D, arteries on the dorsal surface of the ileum. (Robinson.)
The Solitary Glands (noduLi lymphatici solitarii) (Fig. 948) in the large intes-
tine are most abundant in the caecum and vermiform appendix, but are irregu-
larly scattered also over the rest of the intestine. They are similar to those of the
small intestine.
Vessels of the Large Intestine. — The arteries supplying the large intestine give
off large branches, which ramify between the muscular coats supplying them,
and, after dividing into small vessels in the submucous tissue, pass to the
mucous membrane. The caecum, the appendix, and the ileo-caecal valve are sup-
plied by the branches from the anastomotic loops between the right colic and ileo-
colic branches of the superior mesenteric artery (Figs. 945 and 946). In males the
sole blood-supply of the appendix is by the appendicular artery from the posterior
ileo-caecal branch of the ileo-caecal artery (Fig. 946). In the female the appendix
occasionally receives an additional vessel along the appendiculo-ovarian ligament
1328
THE ORGANS OF DIGESTION
from the ovarian artery. The ascending colon is supplied by the right colic, and the
transverse colon by the middle colic branch of the superior mesenteric. The
descending colon is supplied by the left colic branch of the inferior mesenteric,
and the sigmoid flexure by the sigmoid branches of the inferior mesenteric. The
rectum (Fig. 947) is supplied mainly by the superior haemorrhoidal branch of the
inferior mesenteric, but also at its lower end by the middle haemorrhoidal from
the internal iliac, and the inferior haemorrhoidal from the pudic artery. The supe-
FIG. 946. — The arterial blood-supply of the anterior (ventral) surface of the caecum and appendix. .4 ileo-
colio artery; B, caecal-appendicular artery; D, anterior caecal artery; F and G, appendicular artery. Note that
the caecal and appendicular arteries anastomose by fine capillaries, both ventrally and dorsally; C, iliac artery;
1, right colon; 2, external sacculus of caecum (to right of taenium coli); 3, appendix; 4, Iliac, and 5, Psoas
muscles. (Robinson.)
rior haemorrhoidal, 'the continuation of the inferior mesenteric, divides into two
branches, which run down either side of the rectum to within about five inches
of the anus; they here split up into about six branches, which pierce the
muscular coat and descend between it and the mucous membrane in a longi-
tudinal direction, parallel with each other as far as the Internal sphincter, where
they anastomose with the other haemorrhoidal arteries and form a series of loops
around the anus. The veins of the large intestine correspond to the arteries and
join the superior and inferior mesenteric veins which join the portal vein. The veins
of the rectum (Fig. 947) commence in a plexus of vessels which surrounds the lower
extremity of the intestinal canal. In the vessels forming this plexus are small
saccular dilatations just within the margin of the anus (Figs. 944 and 947);
from it about six vessels of considerable size are given off. These ascend between
the muscular and mucous coats for about five inches, running parallel to each
other; they then pierce the muscular coat, and, by their union, form a single
STRUCTURE OF THE LARGE INTESTINE AND RECTUM 1329
SUPERIOR
HEMORRHOIDAL
VEIN
SUPERIOR
HEMORRHOIOAL
ARTERY
MIDDLE
HEMORRHOIDAL
ARTERY
trunk, the superior haemorrhoidal vein, which empties into the inferior mesenteric
branch of the portal vein. This arrangement is termed the haemorrhoidal plexus
(Fig. 473); it communicates with the tributaries of the middle and inferior
haemorrhoidal veins at its commencement, and thus a communication is established
between the systemic and
portal circulations. The in-
ferior haemorrhoidal veins
empty into the internal pudic
veins, and the middle haemor-
rhoidal veins empty into the
internal iliac veins.
The Lymphatics of the Large
Intestine. — The lymphatics
of the large intestine begin
in the mucous membrane and
form an extensive plexus in
the submucosa. There are
also lymphatics more deeply
seated, beneath the simple
follicles. Those from the
ascending colon and trans-
verse colon open into the
glands within the mesocolon
and behind the colon (meso-
colic glands), from which
glands trunks pass to the
superior mesenteric glands.
The lymphatics from the
transverse colon join with
lymph-vessels of the great
omentum, and hence com-
municate with the lymphatics
of the greater curvature of
the stomach. The lymph
from the descending colon,
from the sigmoid and from
the pelvic colon passes to
the glands ajong the inferior
mesenteric artery. The lym-
phatics of the rectum paSS FIG. 947. — The blood-vessels of the rectum and anus, snowing the
£ ,1 ill] distribution and anastomosis on the posterior surface near the termi-
hrst to trie rectal glands, nation ot the gut. (Poirier and Charpy.)
which lie on the muscular
coat of the rectum, next to the glands which lie back of the rectum along the
superior haemorrhoidal artery, and finally to the sacral glands. Lymphatics from
the skin of the anus pass with the lymphatics of the skin to the superficial inguinal
glands. Lymphatics from the anus between the skin margin and Hilton's white
line pass to the hypogastric glands.
The Nerves of the Anus and Rectum. — The nerves of the anus and rectum are
derived from both the sympathetic and cerebro -spinal system. The chief supply
of the rectum is from the mesenteric, sacral, and hypogastric plexuses of the sympa-
thetic. It also obtains small branches from the third, fourth, and fifth sacral nerves.
The lower part of the rectum is much more sensitive than the upper part.
The muscles of the anus and rectum are supplied "from the intricate plexuses
formed by the second, third, fourth, and fifth sacral nerves" (Tuttle). The
84
INFERIOR
HCMORRHOIDAL
ARTERY
1330
THE ORGANS OF DIGESTION
External sphincter is supplied by nerves which contain motor, sensor, and
sympathetic fibres. These nerves come from three sources. "Two filaments
from the branches formed by the third, fourth, and fifth sacral nerves extend
transversely across the ischio-rectal fossa and distribute themselves to the middle
portion of the muscle and to the peri-anal cutaneous surface; a filament which
comes off from the internal pudic just before its division into terminal branches
supplies the anterior portion of the muscle, and is called the anterior sphincterian
nerve ; while a filament coming off from the fifth and sixth sacral nerves passes
down into the hollow of the sacrum, between the Levator ani muscle and the recto-
coccygeus ligament, and finally reaches the posterior superficial surface of the
External sphincter."1 The spinal centre for the nerves of the anus and rectum is
opposite the first lumbar vertebra, and is in practically the same region as the
centre for the genito-urinary organs.
Surface of mucous membrane,
with openings of Lieberkiihn's
follicles.
Lieberkiihn's follicles.
=^= Muscularis mucosie (two layers).
B=" Stibmucous connective tissue.
Solitary gland.
FIG. 948. — Minute structure of large intestine.
Movements and Innervation of the Intestines.
Movements. — As the small intestine is devoid of any sphincter arrangement peristalsis cannot
mix the food as it does in the pyloric portion of the stomach. The process by which the food is
mixed with the secretions and is brought against the intestinal wall for absorption is called
by Cannon "rhythmic segmentation." Rhythmic motions "mix the food and expose it to the
mucosa without advancing it appreciatively along the canal."2 In this process constrictions occur
in the circular fibres, with the result that a collection of stationary food is divided into a number
of segments. In the middle of each segment constrictions appear and the earlier constrictions
relax. Then the latter constrictions relax and the earlier reappear and so on until the food is
thoroughly mixed with digestive secretions. Finally the food is driven on by peristalsis coming
again to rest and being again subjected to "rhythmic segmentation." Cannon says that in the
duodenum "rhythmic segmentation" lasts for several minutes, but in other parts of the intestine
it may continue for half an hour or more, the food which is being subjected to it scarcely moving
along the canal. It is probable that in man there are from seven to eight segmentations per minute
in a given area. It is also probable that there is a sphincter action at the ileo-caecal opening.
Cannon divides the large intestine into two parts: a distal part, in which the material is hard
and lumpy and is "advanced by rings of tonic contraction," and a proximal part, in which the
material is soft. In this part "the common movements are waves of constriction running back-
ward toward the caecum." The resistance of the valve or sphincter enables reversed peristalsis
or antiperistalsis to mix the food. When more food enters from the small intestine, antiperistalsis
ceases, tonic contraction of the caecum and proximal portion of the colon occurs, some of the food
is merged into the transverse colon, and antiperistalsis again begins to act on what remains. The
above facts have been observed in animals and are probably true in man.
Innervation. — The vagus fibres of the small intestine seem to excite contraction of the cir-
cular fibres after a brief preliminary period of inhibition.3 Some observers maintain that the
1 Diseases of the Anus, Rectum and Pelvic Colon. By James P. Tuttle.
* Medical News, May 20, 1905. 3 Bayliss and Starling, Journal cf Physiology, 1899.
SURGICAL ANATOMY OF THE INTESTINES 1331
splanchnic fibres are inhibitory, but others claim that they are also motor. The local reflex of the
small intestine is in Auerbach's plexus. Cannon quotes Bayliss and Starling to the effect that the
pelvic visceral nerves to the large intestine, "arising like the vagus from the central nerve
system, are augmentary nerves, whereas the supply from the sympathetic system is purely
inhibitory in its action." It is further contended that the pelvic visceral nerves are distributed
to the distal colon only. "The region of antiperistalsis does not, therefore, receive motor
impulses from the pelvic nerves."
Surface Form. — The coils of the small intestine occupy the front of the abdomen below the
transverse colon, and are covered more or less completely by the great omentum. For the most
part the coils of the jejunum occupy the left side of the abdominal cavity — i. e., the left lumbar
and inguinal regions and the left half of the umbilical region — whilst the coils of the ileum are
situated to the right, in the right lumbar and inguinal regions, in the right half of the umbilical
region, and also in the hypogastric region. The caecum is situated in the right inguinal region.
Its position varies slightly, but the mid-point of a line drawn from the anterior superior spinous
process of the ilium to the symphysis pubis will about mark the middle of its lower border. It is
comparatively superficial. From it the ascending colon passes upward through the right lumbar
and hypochondriac regions, and becomes more deeply situated as it ascends to the hepatic flexure,
which is deeply placed under cover of the liver. The transverse colon crosses the belly trans-
versely on the confines of the umbilical and epigastric regions, its lower border being on a level
slightly above the umbilicus, its upper border just below the greater curvature of the stomach.
The splenic flexure of the colon is situated behind the stomach in the left hypochondrium, and
is on a higher level than the hepatic flexure. The descending colon is deeply seated, passing
down through the left hypochondriac and lumbar regions to the sigmoid flexure, which is situ-
ated in the left inguinal region, and which can be felt in thin persons, with relaxed abdominal
walls, rolling under the fingers when empty, and when distended forming a distinct bulge. The
usual position of the base of the vermiform appendix is indicated by a point on the cutaneous
surface two inches from the anterior superior spinous process of the ilium, on a line drawn from
this process to the umbilicus. This is known as McBurney's point. Another mode of defining the
position of the base of the appendix is to draw a line between the anterior superior spines of the
ilia and marking the point where this line intersects the right semilunar line.
Upon introducing the finger into the rectum, the membranous portion of the urethra can
be felt, if an instrument has been introduced into the bladder, exactly in the middle line; behind
this the prostate gland can be recognized by its shape and hardness and any enlargement detected;
behind the prostate the fluctuating wall of the bladder when full can be felt, and if thought
desirable it can be tapped in this situation; on either side and behind the prostate the vesiculae
seminales can be readily felt, especially if enlarged by tuberculous disease. Behind, the coccyx
is to be felt, and on the mucous membrane one or two of Houston's folds. The ischio-rectal
fossae can be explored on either side, with a view to ascertaining the presence of deep-seated
collections of pus. Finally, it will be noted that the finger is firmly gripped by the sphincter for
about an inch up the bowel. By gradual dilatation of the sphincter, the whole hand can be
introduced into the rectum so as to reach the descending colon. This method of exploration is
not at the present day employed for diagnostic purposes.
Surgical Anatomy. — The small intestine is much exposed to injury, but, in consequence
of its elasticity and the ease with which one fold glides over another, it is not so frequently rup-
tured as would otherwise be the case. Any part of the small intestine may be ruptured, bur
probably the most common situation is the transverse duodenum, on account of its being more
fixed than other portions of the bowel, and because it is situated in front of the bodies of the
vertebrae, so that if this portion of the intestine is struck a sharp blow, as from the kick of a
horse, it is unable to glide out of the way, but is compressed against the bone and lacerated.
Wounds of the intestine sometimes occur. If the wound is a small puncture, under, it is said,
three lines in length, there may be no extravasation of the contents of the bowel. The mucous
membrane becomes everted and perhaps plugs the little opening. The bowels, therefore, may be
punctured with a fine capillary trocar, in cases of excessive distention of the intestine with gas, with-
out much danger of extravasation. A longitudinal wound gapes more than a transverse wound,
owing to the greater thickness of the circular muscular coat. In closing a wound of the intestine,
use Lembert's inversion sutures, which bring the peritoneal surfaces in contact. Halsted showed
us that these sutures must include the tough submucous coat. The portions of intestine which lie
in the pelvis are inflamed in pelvic peritonitis and become embedded in adhesions. The portions
of intestine \vhich may be present are the termination of the ileum, the portion of small intestine
with the largest mesentery (Treves), the rectum, and the pelvic colon. The small intestine, .and
most frequently the ileum, may become strangulated by internal bands, or through apertures,
normal or abnormal. The bands may be formed in several different ways: they may be old peri-
toneal adhesions from previous attacks of peritonitis; or adherent omentum from the same
cause; or the band may be formed by Meckel's diverticulum, which has contracted adhesions at
its distal extremity; or the band may be the result of the abnormal attachment of some normal
structure, as the adhesion of two appendices epiploicae, or an adherent vermiform appendix or
1332 THE ORGANS OF DIGESTION
Fallopian tube. Intussusception or invagination of the small intestine may take place in any part
of the jejunum ajid ileum, "but the most frequent situation is at the ileo-caecal valve, the valve
forming the apex of the entering tube. This form may attain great size, and it is not uncom-
mon in these cases to find the valve projecting from the anus. Stricture, the impaction of
foreign bodies, and twisting of the gut (volvulus) may lead to intestinal obstruction. Volvulus is
most common in the sigmoid flexure. MeckeFs diverticulum may itself become twisted and
strangulated.
Resection of a portion of the intestine may be required in cases of gangrenous gut; in cases
of intussusception; for the removal of new growth in the bowel; in dealing with artificial anus;
and in cases of rupture. The operation is termed enterectomy, and is performed as follows: the
abdomen having been opened and the amount of bowel requiring removal having been deter-
mined upon, the gut must be clamped on either side of this portion in order to prevent the escape
of any of the contents of the bowel during the operation. The portion of bowel is then separated
above and below by means of scissors. If the portion removed is small, it may be simply removed
from the mesentery at its attachment and the bleeding vessels tied; but if it is large, it will be
necessary to remove also a triangular piece of the mesentery, and having secured the vessels,
suture the cut edges of this structure together. The surgeon then proceeds to unite the cut
ends of the bowel together. He may do it by the operation termed end-to-end anastomosis.
There are many ways of doing this, which may be divided into two classes: one, where the anas-
tomosis is made by means of some mechanical appliance, such as Murphy's button, or one of
the forms of decalcified bone bobbins; and the other, where the operation is performed by
simply suturing the ends of the bowel in such a manner that the peritoneum covering the free
divided ends of the bowel is brought into contact, so that speedy union may ensue.
In some cases after resection each open end of the gut is closed, the side of the terminal portion
is sutured to the side of the initial portion, a fistula is made in each, and the suturing is com-
pleted so as to cause the two fistulae to correspond. A permanent side-to-side opening is
thus made. Lateral anastomosis without resection may be practised between two pieces of
intestine, in order to side-track an intervening, portion, which is the seat of malignant disease or
of an artificial anus. Complete exclusion of a portion of intestine is performed for irremovable
tumors or persistent faecal fistulae of the large intestine. The intestine is cut through above and
below the diseased area and the ends of the healthy gut are united to each other, or the larger
end is closed, an opening is made into the side of the larger end and the smaller end is implanted
in it (lateral implantation). The two ends of the excluded portion are fastened to the skin and
are left open.
In ascites resulting from cirrhosis of the liver benefit occasionally follows the performance of
Talma's operation (epiplopexy) . The abdomen is opened and the omentum is sutured to the
anterior abdominal wall or in the abdominal wound in the hope of establishing a more free
communication between the portal and systemic circulations, thus lowering portal pressure.
External hernia is considered on page 1333.
By the term internal hernia, we mean hernia into the foramen of Winslow, into the retro-
duodenal fossa, into the retro-caecal fossa, 6r into the intersigmoid fossa. Such a hernia produces
the symptoms of acute strangulation of the intestine.
In typhoid fever there is ulceration of Peyer's patches. One of these ulcers may perforate.
The only chance for life is immediate laparotomy and closure of the perforation. This saves
one-fifth, or possibly one-third, of the cases. The incision is made to expose the lower ileum, as
in the vast majority of cases the perforation is in this portion of the gut.
Ulcer of the duodenum is more common than used to be thought. The portion of the duo-
denum between the pylorus and the bile papilla is about four inches in length, and is called by
the Mayo brothers the vestibule of the duodenum. Here the acid gastric juice enters and may pro-
duce an ulcer. The portion of the duodenum below the vestibule is not liable to ulcer, because
it is protected by the alkaline bile and pancreatic juice.
A duodenal ulcer may perforate a large duodenal vessel and cause death from hemorrhage,
or may perforate the intestine and produce septic peritonitis. A perforated ulcer is treated
by laparotomy and closure of the perforation. Occasionally ulceration of the duodenal glands
(Curling's ulcer) may occur in cases of burns, but is not a very common complication.
The vermiform appendix is very liable to become inflamed, the condition being known as
appendicitis. This condition may be set up by a catarrhal inflammation arising in the appen-
dix or derived from the colon. It may remain catarrhal and then subside. It may become
purulent or may be purulent from the beginning. Anything which lessens vital resistance
makes the appendix a ready prey to bacteria. Among causes which lessen resistance are fsecal
concretions, twists of the mesoappendix cutting off the blood-supply, bruises inflicted by the Psoas
muscle (Byron Robinson), blocking of the outlet of the appendix by catarrhal exudate, concre-
tions, proliferated lymphoid tissue, or adhesions. Appendicitis may arise by the appendix becom-
ing twisted, owing to the shortness of its mesentery, in consequence of distention of the caecum.
As the result of inflammation, its blood-supply, which is mainly through one large artery running
in the mesoappendix, becomes interfered with. Again, in rarer cases, the inflammation is set
up by the impaction of a solid mass of faeces or a foreign body in the appendix. The inflammation
SURGICAL ANATOMY OF THE INTESTINES 1333
may result in ulceration and perforation, or in gangrene of the appendix the appendix may be
blocked and full of pus, or abscess may form outside of it (appendwular abscess). These con-
ditions require prompt operative interference, and in cases of recurrent attacks of appendicitis it
is advisable to remove this diverticulum between the attacks. In external hernia the ileum
is the portion of bowel most frequently herniated. When a part of the large intestine is
involved, it is usually the caecum, and this may occur even on the left side. In some few cases
the vermiform appendix has been the part implicated in cases of strangulated hernia, and has
given rise to serious symptoms of obstruction. The diameter of the large intestine gradually
diminishes from the caecum, which has the greatest diameter of any part of the bowel, to the
point of junction of the sigmoid flexure with the rectum, at or a little below which point stricture
most commonly occurs and diminishes in frequency as one proceeds upward to the caecum.
When distended by some obstruction low down, the outline of the large intestine can be defined
throughout nearly the whole of its course — all, in fact, except the hepatic and splenic flexures,
which are more deeply placed; the distention is most obvious in the two flanks and on the front
of the abdomen just above the umbilicus. The caecum, however, is that portion of the bowel
which is, of all, most distended. It sometimes assumes enormous dimensions, and has been
known to give way from the distention, causing fatal peritonitis. The hepatic flexure and the right
extremity of the transverse colon are in close relationship with the liver, and abscess of this viscus
sometimes bursts into the gut in this situation. The gall-bladder may become adherent to the
colon, and gall-stones may find their way through into the gut, where they may become impacted
or may be discharged per anum. The mobility of the sigmoid flexure renders it more liable to
become the seat of a volvulus or twist than any other part of the intestine. It generally occurs
in patients who have been the subjects of habitual constipation, and in whom, therefore, the
mesosigmoid is elongated. The gut at this part being loaded with faeces, from its weight falls
over the gut below, and so gives rise to the twist.
The surgical anatomy of the rectum is of considerable importance. There may be congenital
malformation due to arrest or imperfect development. Thus, there may be no invagination of
the epiblast, and consequently a complete absence of the anus; or the hind-gut may be imper-
fectly developed, and there may be an absence of the rectum, though the anus is developed;
or the invagination of the epiblast may not communicate with the termination of the hind-gut
from want of solution of continuity in the septum which in early foetal life exists between the
two. The mucous membrane is thick and but loosely connected to the muscular coat beneath
and thus favors prolapse, especially in children The vessels of the rectum are arranged as
mentioned above, longitudinally, and are contained in the loose cellular tissue between the
mucous and muscular coats, and receive no support from surrounding tissues, and this favors
varicosity. Moreover, the veins, after running upward in a longitudinal direction for about five
inches in the submucous tissue, pierce the muscular coats, and are liable to become constricted
at this point by the contraction of the muscular wall of the gut. In addition to this there are no
valves in the superior hemorrhoidal veins, and the vessels of the rectum are placed in a depen-
dent position, and are liable to be pressed upon and obstructed by hardened faeces. The anatom-
ical arrangement, therefore, of the hemorrhoidal vessels explains the great tendency to the
occurrence of piles. The presence of the Sphincter ani is of surgical importance, since it is the
constant contraction of this muscle which prevents an ischio-rectal abscess from healing and
tends to cause a fistula. Also, the reflex contraction of this muscle is the cause of the severe pain
complained of in fissure of the anus. The relations of the peritoneum to the rectum are of
importance in connection with the operation of removal of the lower end of the rectum for
malignant disease. The membrane gradually leaves the rectum as it descends into the pelvis;
first leaving its posterior surface, then the sides, and then the anterior surface to become
reflected in the male on to the posterior wall of the bladder, forming the recto-vesical pouch, and
in the female on to the posterior wall of the vagina, forming Douglas's pouch. The recto-vesical
pouch of peritoneum extends to within three inches from the anus, so that it is not desirable
to remove more than two and a half inches of the entire circumference of the bowel, for fear
of the risk of opening the peritoneum. When, however, the disease is confined to the poste-
rior surface of the rectum, or extends farther in this direction, a greater amount of the poste-
rior wall of the gut may be removed, as the peritoneum does not extend on this surface to a
lower level than five inches from the margin of the anus. The recto-vaginal or Douglas's pouch
in the female extends somewhat lower than the recto-vesical pouch of the male, and therefore
it is advisable to remove a less length of the tube in this sex. Of recent years, however, much
more extensive operations have been done for the removal of cancer of the rectum, and in these
the peritoneal cavity has necessarily been opened. If, in these cases, the opening is plugged
with iodoform gauze until the operation is completed and then the edges of the wound in the
peritoneum is accurately brought together with sutures, no evil result appears to follow. For
cases of cancer of the rectum which are too low to be reached by abdominal section, and too
high to be removed by the ordinary operation from below, Kraske has devised an operation
which goes by his name. The patient is placed on his right side and an incision is made from
the second sacral spine to the anus. The soft parts are now separated from the back of the
left side of the sacrum as far as its left margin, and the greater and lesser sacro-sciatic liga-
1334
THE ORGANS OF DIGESTION
ments are divided. A portion of the lateral mass of the sacrum, commencing on the left border
at the level of the third posterior sacral foramen, and running downward and inward through
the fourth foramen to the cornu, is now cut away with a chisel. The left side of the wound
being now forcibly drawn outward, the whole of the rectum is brought into view, and the dis-
eased portion can be removed, leaving the anal portions of the gut, if healthy. The two divided
ends of the gut can perhaps then be approximated and sutured together. Kraske's operation is
in many cases preceded by the performance of iliac colostomy. In cancer high up in the
rectum removal of the growth through the abdomen is sometimes practised, the divided lower
end of the rectum being sutured to the divided upper end (Weir's operation).
The colon frequently requires opening in cases of intestinal obstruction, and by some sur-
geons this operation is performed in cases of cancer of the rectum, as soon as the disease is
recognized, in the hope that the rate of growth may be retarded by removing the irritation pro-
duced by the passage of fecal matter over the diseased surface. The operation of colostomy may
be performed either in the inguinal or lumbar region; but inguinal colostomy (Maydl's opera-
tion) has at the present day superseded the lumbar operation. The main reason for preferring
this operation is that a spur-shaped process can be formed which prevents any fecal matter find-
ing its way past the artificial anus and becoming lodged on the diseased structures below. The
sigmoid flexure being surrounded by peritoneum, a coil can be drawn out of the wound, and
when it is opened transversely a spur is formed, and this pre vents any fecal matter finding its
way from the gut above the opening into that below. The operation is performed by making an
incision two or three inches -in length from a point one inch internal to the anterior superior
spinous process of the ilium, parallel to Poupart's ligament. The various layers of abdominal
muscles are cut through, and the peritoneum opened and sewed to the external skin. The sigmoid
flexure is now sought for, and pulled out of the wound and fixed by pushing a glass bar through
a slit in the mesocolon. The two parts of the loop are sutured together. The intestine is now
sutured to the parietal peritoneum. The wound is dressed, and either immediately or between
the second to the fourth day, according to the requirements of the case, the protruded coil of
intestine is opened. It is opened transversely with the Paquelin cautery.
THE LIVER (HEPAR) (Figs. 949, 950, 951, 952).
The liver is the largest gland in the body, and is situated in the upper and
right part of the abdominal cavity, occupying almost the whole of the right hypo-
chondrium, the greater part of the epigastrium, and extending into the left hypo-
chondrium as far as the mammary line. In the male it weighs from fifty to sixty
Gall-bladder. .
RIGHT LATERAL
LIGAMENT.
LEFT LATERAL
LIGAMENT.
FIG. 949. — The liver. Upper surface. (Drawn from His' method.)
ounces; in the female, from forty to fifty. It is relatively much larger in the foetus
than in the adult, constituting, in the former, about one-eighteenth, and in the
latter, about one-thirty-sixth of the entire body-weight. Its greatest transverse
THE LIVER
1335
measurement is from eight to nine inches. Vertically, near its lateral or right
surface, it measures about six or seven inches, while its greatest antero-posterior
Great splanchnic
nerve piercing
crus.
Receptaculum
chyli.
Semilunar
ganglion.
nerve piercing
crus.
Semilunar
ganglion.
FIG. 950. — The relations of the viscera and large vessels of the abdomen. (Seen from behind,
the last thoracic vertebra being well raised.)
diameter is on a level with the upper end of the right kidney and is from four to
five inches. Opposite the vertebral column its measurement from before backward
is reduced to about three inches. Its consistence is that of a soft solid ; it is,
1336 THE ORGANS OF DIGESTION
however, friable and easily lacerated; its color is a dark reddish7brown, and its
specih'c gravity is 1.05.
To obtain a correct idea of its shape, it must be hardened in situ, and it will
then be seen to present the appearance of a wedge, the base of which is directed
to the right and the thin edge toward the left. Symington describes its shape as
that "of a right-angled triangular prism with the right angles founded off." It
possesses five surfaces, viz., a superior, inferior, anterior, posterior, and a right lateral
surface.
The superior and anterior surfaces are separated from each other by a thick
rounded border, and are attached to the Diaphragm and anterior abdominal wall
by a triangular or falciform fold of peritoneum, the suspensory or falciform liga-
ment, which divides the liver into two unequal parts, termed the right and left
lobes (Figs. 949, 953, and 954). Except along the line of attachment of this liga-
ment to the liver, the superior and anterior surfaces are covered by peritoneum.
The Superior Area or Surface (fades superior] (Fig. 949). — The superior
area or surface comprises a part of both lobes. Spalteholz considers as parts of
the superior surface the right surface and the anterior surface. The superior sur-
face is convex, and fits under the vault of the Diaphragm ; its central part, however,
presents a shallow depression, the cardiac depression (impressio cardiaca), which
corresponds with the position of the heart on the upper surface of the Diaphragm.
It is separated from the anterior, posterior, and lateral surfaces by thick, rounded
borders. Its left extremity is continued into the under surface by a prominent
sharp margin.
The Anterior Area or Surface. — The anterior area or surface is large and
triangular in shape, comprising also a part of both lobes. It is directed forward,
and the greater part of it is in contact with the Diaphragm, which separates it
from the right lower ribs and their cartilages. In the middle line it lies behind
the ensiform cartilage, to the left of which it is protected by the seventh and
eighth left costal cartilages. In the angle between the diverging rib cartilages
of opposite sides the anterior surface is in contact writh the abdominal wall. It
is continuous with the inferior surface by a sharp margin, and with the superior
and lateral surfaces by thick rounded borders.
The Lateral Right Area or Surface (Figs. 949 and 951). — The lateral or right
area or surface is convex from before backward and slightly so from above down-
ward. It is directed toward the right side, forming the base of the wedge, and
lies against the lateral portion of the Diaphragm, which separates it from the
lower part of the left pleura and lung, outside which are the right costal arches
from the seventh to the eleventh inclusive.
The Under or Visceral Area or Surface (fades inferior) (Figs. 951 and 952).—
The under or visceral area or surface is uneven, concave, directed downward and
backward and to the left, and is in relation with the stomach and duodenum, the
hepatic flexure of the colon, and the right kidney. The surface is divided by a
longitudinal fissure into a right and a left lobe, and is almost completely invested
by peritoneum; the only parts where this covering is absent are where the gall-
bladder is attached to the liver and at the transverse fissure, where the two layers
of the lesser omentum are separated from each other by the blood-vessels and
duct of the viscus. The under surface of the left lobe presents to the right and
near the centre a rounded eminence, the omental tuberosity (tuber omentale] (Fig.
951), which is in contact with the lesser omentum. It is surrounded by a broad
depression, the gastric surface or impression (impressio gastrica), with which the
stomach is in contact. Between the gall-bladder and the left lobe is the quad-
rate lobe. The quadrate lobe is bounded to the left by the umbilical fissure or the
fissure of the umbilical vein (fossa venae umbilicalis], which is the anterior portion
of the longitudinal fissure and lodges the round ligament. The under surface of
the right lobe is divided into two unequal portions by a fossa, which lodges the
THE LIVER 1337
gall-bladder and is called the fossa vesicalis (fossa- vesicae felleae); the portion to
the left, the smaller of the two, is somewhat oblong in shape, its antero-posterior
diameter being greater than its transverse. It is known as the quadrate lobe,
and is in relation with the pyloric end of the stomach (impressio pyloricd) and the
first portion of the duodenum. The portion of the under surface of the right
lobe to the right of the fossa vesicalis presents two shallow concave impressions,
one situated behind the other, the two being separated by a ridge. The anterior
of these two impressions, the colic impression (impressio colica) , is produced by the
hepatic flexure of the colon; the posterior, the renal impression (impressio renalis},
is occupied by the upper end of the right kidney (Fig. 951). To the inner side of
the latter impression is a third and slightly marked impression, lying between it
and the neck of the gall-bladder. This is caused by the second portion of the
duodenum, and is known as the duodenal impression (impressio duodenalis). Just
in front of the postcava is a narrow strip of liver tissue, the caudate lobe, which
connects the right inferior angle of the Spigelian lobe to the under surface of the
right lobe. Immediately below it is the foramen of Winslow.
The Posterior Area 'or Surface (fades posterior] (Figs. 950 and 952).— The
posterior area or surface is rounded and broad behind the right lobe, but narrow
on the left. Over a large part of its extent it is not covered by peritoneum; this
uncovered area (Fig. 951) is about three inches broad, and is in direct contact with
the Diaphragm, being united to it by areolar tissue. In this tissue are numerous
small veins which join the portal circulation to the systemic circulation. The
uncovered area is marked oft' from the upper surface by the line of reflection of
the upper or anterior layer of the coronary ligament. It is in the same way
marked oft' from the under surface of the liver by the line of reflection of the lowrer
layer of the coronary ligament (Fig. 953). In its centre the posterior surface is deeply
notched for the vertebral column and crura of the Diaphragm, and to the right
of this it is indented for the postcava, which is often partly embedded in its sub-
stance. Close to the right of this indentation and immediately above the renal
impression is a small triangular depressed area, the suprarenal impression (impressio
suprarenalis) (Fig. 951), the greater part of which is devoid of peritoneum; it
lodges the right suprarenal capsule, which is inserted between the liver and Dia-
phragm. To the left of the fossa for the postcava is the Spigelian lobe, which lies
between the fissure for the postcava and the fissure for the ductus venosus. Below
and in front it projects and forms part of the posterior boundary of the transverse
fissure. Here, to the right, it is connected with the under surface of the right lobe
of the liver by the caudate lobe, and to the left it presents a tubercle, the tuber-
culum papillare (Fig. 951). It is opposite the tenth and eleventh thoracic vertebrae,
and rests upon the aorta and crura of the Diaphragm, being covered by the peri-
toneum of the lesser sac. The lobe is nearly vertical in position, and is directed
backward; it is longer from above downward than from side to side, and is some-
what concave in the transverse direction. On the posterior surface to the left
of the Spigelian lobe is a groove, the oesophageal groove (impressio oesophagea),
indicating the position of the abdominal portion of the oesophagus (Fig. 951).
Prof. Cunningham divides the liver into two surfaces, a visceral and a parietal,
and subdivides the parietal surface into a posterior area and superior area, an ante-
rior area and a right area. The parietal surface is separated from the visceral
surface by the inferior border or margin.
The inferior border or margin (margo inferioris), posteriorly, is rather ill defined.
It is the lower margin of the posterior surface; it follows the line of rib and is in
contact with the right kidney. At the right side the lower margin is thick and
distinct, and, as a rule, projects slightly below the thorax. The front of the
inferior margin is called the anterior margin (margo anterior}. It is a sharp edge
which, on inspiration, corresponds to an oblique line on the abdominal wall
1338
THE ORGANS OF DIGESTION
drawn from "a point half an inch below the margin of the ribs (tip of tenth
costal cartilage), on the right side, to a point an inch below the nipple on the
left, and extending down in the middle line to a point half-way between the
gladiolus and the umbilicus."1
In men the anterior margin of the liver often corresponds to the lower margin
of the ribs, but in women and children it is usually below the ribs in the line
Sup
rarenal
impression
(non-peritoneal).
Suprarenal
impression
(peritoneal).
Tuberculum
caudatum.
Tubercu
papillare.
7
Umbilical fissure. Transverse fissure.
FIG. 951. — The liver. Posterior and inferior surfaces. (Drawn from His's models.)
indicated above. Opposite the attachment of the falciform ligament the anterior
border often exhibits a deep notch, the umbilical notch (incisura umbilicalis},
which is the anterior end of the fossa venae umbilicalis. Another notch, some-
times present, corresponds to the fundus of the gall-bladder, and is known as the
notch of the gall-bladder (incisura vesicae felleae).
The left extremity of the inferior margin of the liver is thin and flattened from
above downward. The margin passes posteriorly around the free end of the left
lobe and terminates posteriorly at the oesophageal groove.
Fissures. — Five fissures are seen upon the under and posterior surfaces of the
liver, which serve to divide it into five lobes. They are: the umbilical fissure,
the fissure of the ductus venosus, the transverse fissure, the fissure for the gall-bladder,
and the fissure for the postcava. They are arranged in the form of the letter H.
The left limb of the H is known as the longitudinal fissure. The right limb is formed
in front by the fissure for the gall-bladder, and behind by the fissure for the post-
cava; these two fissures are separated from each other by the caudate lobe. The
connecting bar of the H is the transverse or portal fissure. It separates the quad-
rate lobe in front from the caudate and Spigelian lobes behind.
The Longitudinal Fossa or Fissure (fossa longitudinalis sinistra}. — The longi-
tudinal fissure is a deep groove, which extends from the notch on the anterior
margin of the liver to the upper border of the posterior surface of the organ. It
separates the right and left lobes; the transverse fissure (Fig. 951) joins it, at
right angles, and divides it into two parts. The anterior part is called the um-
bilical fossa or fissure (fossa venae umbilicalis') (Fig. 951); it is deeper than the
posterior, and lodges the umbilical vein in the foetus, and its remains (the round
ligament) in the adult; the posterior part contains the ductus venosus, and is
known as the fissure of the ductus venosus. This fissure lies between the quadrate
lobe and the left lobe of the liver, and is often partially bridged over by
prolongation of the hepatic substance, the pons hepatis.
1 Ambrose Birmingham, in Cunningham's Text-book of Anatomy.
THE LIVER
1339
The Fissure or Fossa of the Ductus Venosus (fossa ductus venosi) (Fig. 951) is
the back part of the longitudinal fissure, and is situated mainly on the posterior
surface of the liver. It lies between the left lobe and the lobe of Spigelius. It
lodges in the foetus the ductus venosus, and in the adult a slender fibrous cord,
the obliterated remains of that vessel.
The Transverse or Portal Fissure (porta hepatis) (Fig. 951). — The transverse or
portal fissure is a short but deep fissure, about two inches in length, extending
transversely across the under surface of the left portion of the right lobe, nearer to
its posterior surface than its anterior border. It joins, nearly at right angles, with
the longitudinal fissure, and separates the quadrate lobe in front from the cau-
date and Spigelian lobes behind. By the older anatomists this fissure was con-
sidered the gateway (porta) of the liver; hence the large vein which enters at this
fissure was called the portal vein (Fig. 952). Besides this vein, the fissure trans-
mits the hepatic artery and nerves, and the hepatic duct and lymphatics. At
their entrance into the fissure, the hepatic duct lies in front and to the right,
the hepatic artery to the left, and the portal vein behind and between the duct
and artery.
CEsophageal groove. Portal vein. Suprarenal impression.
RIGHT LATERAL
LIGAMENT.
LIGAMENTUM —
TERES.
Hepatic artery.
Common bile-duct.
FIG. 952. — Posterior and under surfaces of the liver. (From Ellis.)
The Fossa or Fissure for the Gall-bladder (fossa vesicae felleae). — The fossa or
fissure for the gall-bladder is a shallow, oblong fossa, placed on the under surface
of the right lobe, parallel with the longitudinal fissure. It extends from the
anterior free margin of the liver, which is notched for its reception, to the right
extremity of the transverse fissure.
The Fissure or Fossa for the Postcava (fossa venae cavae) (Fig. 951). — The
fissure or fossa for the postcava is a short, deep fissure, in some cases a com-
plete canal, in consequence of the substance of the liver occasionally surrounding
the postcava. It extends obliquely upward from the lobus caudatus, which sepa-
rates it from the transverse fissure, on the posterior surface of the liver, and sepa-
rates the Spigelian from the right lobe. On slitting open the postcava the orifices
of the hepatic veins will be seen opening into this vessel at its upper part, after
perforating the floor of this fissure.
Lobes. — The lobes of the liver, like the ligaments and fissures, are five in
number — the right lobe, the left lobe, the lobus quadratus, the lobus Spigelii, and
the lobus caudatus, the last three being merely parts of the right lobe.
1340 THE ORGANS OF DIGESTION
The Right Lobe (lobus hepatis dexter) (Figs. 949 and 951). — The right lobe is
much larger than the left; the proportion between them being as six to one. It
occupies the right hypochondrium, and is separated from the left lobe, on its upper
and anterior surfaces by the falciform ligament; on its under and posterior surfaces
by the longitudinal fissure; and in front by the umbilical notch. It is of a some-
what quadrilateral form, its under and posterior surfaces being marked by three
fissures — the transverse fissure, the fissure for the gall-bladder, and the fissure for
the postcava, which separate its left part into three smaller lobes — the lobus
Spigelii, lobus quadratus, and lobus caudates. On it are seen four shallow impres-
sions: one in front, for the hepatic flexure of the colon; a second behind, for
the right kidney; a third internal, between the last-named and the gall-bladder,
for the second part of the duodenum; and a fourth on its posterior surface, for the
suprarenal capsule.
The Lobus Quadratus or Square Lobe (Figs. 951 and 952) is situated on the
under surface of the right lobe, is bounded in front by the inferior margin of the
liver; behind, by the transverse fissure; on the right, by the fissure of the gall-
bladder; on the left, by the umbilical fissure.
The Lobus Spigelii (lobus caudatus [Spigeli]) (Figs. 951 and 952) is situated
upon the posterior surface of the right lobe of the liver. It looks directly back-
ward, and is nearly vertical in direction. It is bounded, above, by the upper layer
of the coronary ligament; below, by the transverse fissure; on the right, by the
fissure for the postcava; and on the left, by the fissure for the ductus venosus.
Its left upper angle forms part of the groove for the oesophagus. What is here
called the lobus Spigelii, Spalteholz calls the lobus caudatus of Spigelius.
The Lobus Caudatus or Tuberculum Caudatum (processus caudatus) (Fig. 951), or
tailed lobe, is a small elevation of the hepatic substance extending obliquely out-
ward, from the lower extremity of the Spigelian lobe to the under surface of the
right lobe. It is situated behind the transverse fissure, and separates the fissure
for the gall-bladder from the commencement of the fissure for the postcava.
What is here called the lobus caudatus, Spalteholz calls the processus caudatus
of the lobus caudatus of Spigelius.
The Left Lobe (lobus hepatis sinister) (Figs. 949 and 951). — The left lobe is
smaller and more flattened than the right. It is situated in the epigastric and
left hypochondriac regions. Its upper surface is slightly convex; its under sur-
face is concave, and presents a shallow depression for the stomach, the gastric
impression. This is situated in front of the groove for the oesophagus, and is
separated from the longitudinal fissure by the omental tuberosity, which lies against
the small omen turn and lesser curvature of the stomach. The posterior end of
the left lobe frequently exhibits a flat projection, composed of connective tissue,
and called the appendix fibrosus hepatis. In the adult, portions only of bile-ducts
are present in it. In the newborn it is a definite portion of secreting liver sub-
stance, which later undergoes connective-tissue transformation.
Ligaments. — The liver is connected to the under surface of the Diaphragm
and the anterior walls of the abdomen and the postcava by six ligaments, four
of which are peritoneal folds; the other two, which are the round ligament and
the ligament of the ductus venosus, are fibrous cords, resulting from the obliteration
of foetal vessels. These ligaments are the falciform, two lateral, coronary, round,
and the ligament of the ductus venosus. It is also attached to the lesser curvature
of the stomach by the gastro-hepatic or small omen turn.
The Falciform, Broad or Suspensory Ligament (ligamentum falciforme hepatis)
(Figs. 949, 953, and 954). — The falciform or suspensory ligament is a broad and
thin antero-posterior peritoneal fold, falciform in shape, its base being directed
downward and backward, its apex upward and backward. It is attached by one
margin to the under surface of the Diaphragm, and the posterior surface of the
THE LIVER
1341
sheath of the right Recttis muscle to within one inch of the umbilicus; by its
hepatic margin it extends from the notch on the anterior margin of the liver, as
far back as its posterior surface.
The free edge or base of the falciform ligament reaches from a little above and to
the right of the umbilicus to the umbilical fissure on the anterior margin of the liver.
This free edge contains between its folds the round ligament of the liver. On the
posterior surface of the liver the two peritoneal folds which constitute the falci-
form ligament separate, the right fold passing into the upper fold of the coronary
ligament, the left fold passing into the upper fold of the left lateral ligament.
CORONARY
LIGAMENT
RIGHT
LATERAL .
LIGAMENT
FALCIFORM
LIGAMENT
Fir,. 9o3. — The peritoneal ligaments of the liver. (Schematic.) (Poirier and Charpy.)
The Lateral Ligaments (Figs. 949 and 953). — The lateral ligaments are two in
number, and are called the right and left lateral ligaments.
The Right Lateral Ligament (ligamentum triangulare dextrum) (Figs. 949 and
953) is in reality the right extremity of the coronary ligament. This ligament is
triangular in form, runs from the liver to the Diaphragm, and is forrfied by the
apposition of the upper and lower layers of the coronary ligament. It is attached
to the liver between its lateral and inferior surfaces.
The Left Lateral Ligament (ligamentum triangulare sinistrum) (Figs. 949 and
953) is also formed by apposition of the upper and lower layers of the coronary
ligament. It is triangular in form,
runs from the liver to the Dia-
phragm, and is longer than the right
lateral ligament. It is attached to
the upper surface of the left lobe,
where it lies, in front of the oesopha-
geal opening in the Diaphragm.
The Coronary Ligament (ligamentum
coronarium hepatis) (Figs. 949 and
953). — The coronary ligament con-
nects the posterior surface of the liver
to the Diaphragm. It is formed by
the reflection of the peritoneum from
the Diaphragm on to the upper and NA<
lower margins of the posterior sur-
face of the liver. The coronary liga-
ment Consists of tWO layers, which FIG. 954.— Diagram to show the relations of the falci-
,• i • i •-! ,1 form or suspensory and round ligaments to the liver and
are COntinUOUS On each Side With the the abdominal wall. (Gerrish.)
lateral ligaments, and, in front, with
the falciform ligament. Between the layers a large triangular area is left uncovered
by peritoneum, and is connected to the Diaphragm by firm areolar tissue.
1342 THE ORGANS OF DIGESTION
The Round Ligament (ligamentum teres hepatis) (Figs. 952 and 954). — The
round ligament is a fibrous cord resulting from the obliteration of the foetal umbil-
ical vein. It ascends from the umbilicus, in the free margin of the falciform
ligament, to the notch in the anterior border of the liver, from which it may be
traced along the umbilical fissure on the under surface of the liver, to the left
branch of the portal vein.
The Ligament of the Ductus Venosus (ligamentum venosum [Arantii]) is com-
posed of slender bundles of fibrous tissue, and results from the obliteration of the
ductus venosus of the foetus. It arises from the left branch of the portal vein,
almost opposite the insertion of the round ligament, passes backward in the fissure
of the ductus venosus, and, as it emerges from the liver, is attached to the postcava.
Support and Movability of the Liver. — The liver is movable within certain
narrow limits. It moves with respiration. On inspiration it moves down with
the Diaphragm to distinctly below the costal arch in the right nipple line.
Much discussion has taken place as to what supports the liver in place. Syming-
ton asserted that the ligaments do not give support, because they lie relaxed.
Other observers (Graham, Steele) apparently demonstrate that the peritoneal
ligaments do give some support to the liver. The connective tissue which unites
the uncovered area of the right lobe of the liver to the Diaphragm and the hepatic
veins which join the postcava (Faure) do give distinct support. The chief factor
in the support of the liver is the intra-abdominal pressure resulting from the
tonic contraction of the abdominal muscles. When abdominal tension is normal
the intestines are driven up and become a bed for the liver. Intrahepatic vascular
tension aids in supporting the liver (Glenard).
Abnormalities of the Liver. — The liver may be divided into many lobules, and
such lobulation is most evident on the parietal surface of the right lobe. Lobula-
tion is probably a pathological change. Occasionally the right lobe is small and
the left large.
The editor, in performing an abdominal operation, encountered a liver the
left lobe of which was so large and the right so small as to suggest transposition
or rotation of the organ. Such a change may result from abnormality of the
foetal circulation or from syphilitic disease of the right lobe, producing cicatricial
contraction.1 The left lobe may be very small; sometimes it is rudimentary.
When the left lobe is very small an unusual amount of stomach is visible, and the
entire gall-bladder can be seen from the front. In such a case the gall-bladder is
usually displaced and it may actually "lie with its long axis in the transverse axis
of the body."2
Atrophy of the left lobe is usually a congenital defect, but may result from
syphilis. Small accessory lobes, about one inch in length, are not uncommon, and
they are most often met with on the visceral surface of the right lobe. "WTien
markedly pedunculated, they may form accessory livers. The Spigelian lobe is
sometimes curiously pedunculated."3
Accessory livers are fragments of hepatic tissue or rests, which are entirely
separated from the liver. They are seldom met with. When they do exist their
most common situation is in the suspensory ligament, but they have been found
in the great omentum, in the peritoneum, wall of the gall-bladder, and in other
situations. They may be congenital or may be due to atrophy of the pedicle of an
accessory lobe or of a pedunculated lobe. Tight lacing alters the shape and posi-
tion of the liver (Fig. 955). It may flatten the dome and increase the length of
the anterior surface, this change being especially obvious in the right lobe, and a
costal groove may be formed by the pressure of a rib. "When the elongated
right lobe passes over the right kidney, there is atrophy of the hepatic substance
1 H. D. Rolleston on Diseases of the Liver. - Ibid. 3 Ibid.
THE LIVER
1343
and thickening of the capsule, which is opaque and forms a hinge-like ligament
between the main part of the right lobe above and the constricted lower portion.
This lobe is variously termed partial hepatoptosis, constriction lobe, or the sus-
tentacular formation of the right lobe (Hertz). The constriction furrow is pro-
duced by the pressure of the corset in front and the resistance of the kidney
behind. The constriction lobe tapers to a point, so that the shape of the liver, as
seen from the front, is that of a right-angled triangle, with the apex downward."1
The condition resembles Riedel's lobe. The left lobe may also project down,
DIAPHRAGMATIC
GROOVE
FIG. 955.— Deformed female liver. (Poirier and Charpy.)
but not so markedly. Tight lacing may cause the entire organ to occupy a level
higher than normal. Such a liver is thick and excessively convex above and
thin below, and reaches to or laps over the spleen. In severe cases the superior
surface is thrown into antero-posterior creases or folds. Linguifonn or tongue-like
lobe, Riedel's lobe or floating lobe (Fig. 955), may be congenital, may be due to tight
lacing, or may arise in cholelithiasis or cholecystitis from the traction of adhesions.
Such a lobe comes off from the right lobe. It may be a tapering mass of liver
tissue, it may have a thin pedicle of liver tissue, or its pedicle may be merely a
double fold of peritoneum. The gall-bladder may lie upon its under surface, or
may be placed to the left of it.
Vessels. — The blood-vessels connected with the liver are the hepatic artery, the
portal vein and the hepatic veins.
The Hepatic Artery and Portal Vein (Figs. 421, 422, 488, and 957), accompanied
by numerous lymphatics and nerves, ascend to the transverse fissure between the
layers of the gastro-hepatic omen turn, and in front of the foramen of Winslow.'
The hepatic duct, lying in company with them, descends from the transverse fissure
between the layers of the same omentum. The relative position of the three
structures in the lesser omentum (Fig. 872) is as follows: the hepatic duct lies to
the right, the hepatic artery to the left, and the portal vein behind and between
the other two. They enter the transverse fissure in the above-described order, but
in that fissure undergo rearrangement, the duct being in front, the artery in the
1 Rolleston, on Diseases of the Liver.
1344
THE ORGANS OF DIGESTION
middle, and the vein behind. The artery, the vein, and the duct divide into a
right and left branch and several smaller branches, and within the organ the
vessels from the three sources accompany each other and divide at the same
points; so each branch of the portal vein is accompanied by a branch of the
FIG. 956. — Schematic section of the liver. The fibron tunic shown in black and the capsule of Glisson in red.
hepatic artery and of the duct. They are enveloped in a loose areolar tissue, the
capsule of Glisson (Fig. 956), which accompanies the vessels in their course through
the portal canals in the interior of the organ.
The Hepatic Veins (Fig. 424). — The hepatic veins convey the blood from the liver.
They commence in the substance of the liver, in the capillary terminations of the
portal vein and hepatic artery; these tributaries, gradually uniting, usually form
three veins, which converge toward the posterior surface of the liver and open
into the portion of the postcava situated in the groove at the back part of this
organ. Of these three veins, one from the right and another from the left lobe
open obliquely into the postcava; that from the middle of the organ and lobus
Spigelii having a straight course.
COMMON DUCT
FORAMEN OF
WINSLOW
DUODENUM
FIG. 957. — The relations of the vessels as they pass into the transverse fissure of the liver. (Poirier and Charpy.)
The hepatic veins have very little cellular investment; what there is binds their
parietes closely to the walls of the canals through which they run; so that, on
section of the organ, these veins remain widely open and solitary (Fig. 959),
and may be easily distinguished from the branches of the portal vein (Fig. 960),
THE LIVER
1345
which are more or less collapsed, and always accompanied by an artery and duct,
the hepatic veins are destitute of valves.
Structure. — The substance of the liver is composed of lobules held together by
extremely fine areolar tissue, and of the ramifications of the portal vein, hepatic
duct, hepatic artery, hepatic veins, lymphatics, and nerves, the whole being
invested by a serous and a fibrous coat.
The Serous Coat (tunica serosa). — The serous coat is derived from the perito-
neum, and invests the greater part of the surface of the organ. It is intimately
adherent to the fibrous coat.
The Areolar or Fibrous Coat (capsula fibrosa [Glissoni]). — The areolar or fibrous
coat lies beneath the serous investment and covers the entire surface of the organ.
It is difficult of demonstration, excepting where the serous coat is deficient. At
the transverse fissure it is thick and evident, is known as the capsule of Glisson,
and envelops the vessels which enter the liver and passes with them along the
portal canals. The areolar tissue which surrounds and binds together the liver
lobules is continuous with the areolar coat.
The Lobules (lobuli hepatis) (Fig. 962). — The lobules form the chief mass of
the hepatic substance; they may be seen either on the surface of the organ or by
making a section through the gland. They are small granular bodies about the size
of a millet-seed, measuring from one-twentieth to one-tenth of an inch in diameter.
In the human subject their outline is very irregular, but in some of the lower
animals (for example, the pig) they are well defined, and when divided transversely
have a polygonal outline. If divided longitudinally they are more or less foliated
or oblong. The bases of the lobules are clustered around the smallest radicles
of the hepatic veins (sublobular veins), to which each is connected by means of a
small branch which issues from the centre of the lobule (intralobular vein). The
remaining part of the surface of each lobule is imperfectly isolated from the sur-
rounding lobules by a thin stratum of areolar tissue in which are ducts and a plexus
FIG. 958. — The hepatic cells at different stages of digestion. (Heidenhain.)
of vessels, the interlobular plexus (Figs.. 961 and 962). In some animals, as the
pig, the lobules are completely isolated one from another by this interlobular
areolar tissue.
If one of the sublobular veins be laid open, the bases of the lobules may be
seen through the thin wall of the vein on which they rest, arranged in the form
of a tessellated pavement, the centre of each polygonal space presenting a minute
aperture, the mouth of an intralobular vein (Fig. 959).
MICROSCOPIC APPEARANCE. — Each lobule is composed of a mass of cells, hepatic
cells (Fig. 958), surrounded by a dense capillary plexus, composed of vessels which
penetrate from the circumference to the centre of the lobule, and terminate in a
single straight central vein, which runs through its centre, to open at its base into
one of the radicles of the hepatic vein. Between the cells are also the minute com-
mencements of the bile-ducts. Therefore in the lobule we have all the essentials of
a secreting gland; that is to say: (1) cells, by which the secretion is formed; (2)
blood-vessels, in close relation with the cells, containing the blood from which
the secretion is derived; and (3) ducts, by which the secretion, when formed, is
carried away. Each of these structures will have to be further considered.
85
1346
THE ORGANS OF DIGESTION
(1) The Hepatic Cells are epithelial in nature and of more or less spheroidal form,
but may be rounded, flattened, or many-sided from mutual compression. They
vary in size from the j^Vo" to the WinF °f an mcn m diameter. They consist of a
honeycomb network (Klein) without any cell-wall, and contain one or sometimes
two distinct nuclei. In the nucleus is a highly refracting nucleolus with granules.
Embedded in the honeycomb network are numerous yellow particles, the coloring
matter of the bile, and oil-globules. The cells adhere together by their surfaces so
as to form rows, which radiate from the centre to the circumference of the lobules.1
As stated above, they are the chief agents in the secretion of the bile.
(2) The Blood-vessels. — The blood in the capillary plexus around the liver-cells
is brought to the liver principally by the portal vein, but also to a certain extent
by the hepatic artery. For the sake of clearness the distribution of the blood
derived from the hepatic artery may be considered first.
The Hepatic Artery, entering the liver at the transverse fissure with the portal
vein and hepatic duct, ramifies with these vessels through the portal canals. It
gives off vaginal branches which ramify in the capsule of Glisson, and appear to
be destined chiefly for the nutrition of the coats of the large vessels, the ducts,
and the investing membranes of the liver. It also gives off capsular branches
which reach the surface of the organ, terminating in the fibrous coat in stellate
plexuses. Finally it gives off interlobular branches (rami arteriosi interlobular es)
which form a plexus on the outer side of each lobule, to supply its wall and the
accompanying bile-ducts. From this plexus lobular branches enter the lobule
Hepatic
artery.
Portal vein.
Orifices of intralobular veins.
FIG. 959. — Longitudinal section of an hepatic
vein. (After Kiernan.)
rtion of
canal from
which vein
has been
removed.
FIG. 960. — Longitudinal section of a small portal
vein and canal. (After Kiernan.)
and end in the capillary network between the cells. Some anatomists, however,
doubt whether it transmits any blood directly to the capillary network.
The Portal Vein also enters at the transverse fissure and runs through the
portal canals, enclosed in Glisson's capsule, dividing into branches in its course,
which finally break up into a plexus, the interlobular plexus, in the interlobular
spaces. In their course these branches receive the vaginal and capsular veins,
corresponding to the vaginal and capsular branches of the hepatic artery (Fig.
THE LIVER
1347
960) . Thus it will be seen that all the blood carried to the liver by the portal vein
and hepatic artery, except perhaps that derived from the interlobular branches of
the hepatic artery, directly or indirectly finds its way into the interlobular plexus.
From this plexus the blood is carried into the lobule by fine branches which pierce
its wall and then converge from the circumference to the centre of the lobule, form-
Intralobular vein.
Trunk of intralobular
vein.
FIG. 961. — Horizontal section of liver (dog.)
ing a number of converging vessels which are connected by transverse branches
(Figs. 961 and 962). In the interstices of the network of vessels thus formed are
situated, as before said, the liver-cells: and here it is that the blood is brought into
intimate connection with the liver-^cells and the bile is secreted. Arrived at the
centre of a lobule, all these minute vessels empty themselves into one vein, of
considerable size, which runs down the centre of the lobule from apex to base
and is called the intralobular or central vein (vein interlobularis) (Fig. 962). At the
TT»
FIG. 962. — Horizontal section of a liver lobule: 1, central vein; 2, converging vessels; 3, interlobular plexus.
(Poirier and Charpy.)
base of the lobule this vein opens directly into the sublobular vein, with which the
lobule is connected, and which, as before mentioned, is a radicle of the hepatic vein.
The sublobular veins, uniting into larger and larger trunks, end at last in the
hepatic veins, which do not receive any intralobular veins. Finally, the hepatic
veins, as mentioned on page 767, converge to form three large trunks which open
into the postcava, while that vessel is situated in the fissure appropriated to it
at the back of the liver.
1348
THE ORGANS OF DIGESTION
(3) The Ducts. — Having shown how the blood is brought into intimate relation
with the hepatic cells in order that the bile may be secreted, it remains now only
to consider the way in which the secretion, having been formed, is carried away.
FIG. 963. — .Y-ray picture of the bile-ducts and the pancreatic ducts. (Robinson.)
Several views have prevailed as to the mode of origin of the hepatic ducts; it
seems, however, to be clear that they commence by little passages which are
formed between the cells, and which have been termed intercellular biliary pass-
ages, bile-capillaries or bile-canaliculi (ductus biliferi) . These passages are merely
little channels or spaces left between the contiguous surfaces of two cells or in the
INTER-
LOBULAR
BRANCHES
Biliary duct.
FIG. 964. — Section of liver.
FIG. 965. — A transverse section of a small portal canal
and its vessels. (Kiernan.)
angle where three or more liver-cells meet (Fig. 964), and it seems doubtful
whether there is any delicate membrane forming the wall of the channel.
Heidenhain, however, thinks they have coats. The channels thus formed radi-
ate to the circumference of the lobule, and, piercing its wall, form a plexus
THE LIVER 1349
(interlobular} between the lobules. From this plexus interlobular ducts (ductus
interlobular es} are derived which pass into the portal canals, become enclosed in
Glisson's capsule, and, accompanying the portal vein and hepatic artery (Fig.
952), join with other ducts to form two main trunks, the right and left branches of
the hepatic duct, which leave the liver at the transverse fissure, and by their union
form the hepatic duct.
STRUCTURE. — The coats of the smallest biliary ducts, which lie in the inter-
lobular spaces, are a connective-tissue coat, in which are muscle-cells, arranged
both circularly and longitudinally, and an epithelial layer, consisting of short
columnar cells. In the larger ducts, which lie in the portal canals, there are a
number of orifices disposed in two longitudinal rows, which were formerly regarded
as the openings of mucous glands, but which are merely the orifices of tubular
recesses. They occasionally anastomose, and from the sides of them saccular
dilatations are given off.
Lymphatics of the Liver (Fig. 504). — The lymphatics in the substance of the liver
commence in lymphatic spaces around the capillaries of the lobules ; they accompany
the vessels of the interlobular plexus, often enclosing and surrounding them,
These unite and form larger vessels, which run in the portal canals, enclosed in
Glisson's capsule, and emerge at the portal fissure to be distributed in the manner
described. Other superficial lymphatics arise from the superficial lobules, pass
under the peritoneum, and form a close plexus, where this membrane covers
the liver. The first-named group of lymphatics give origin to the deep collecting
trunks, the second to the superficial collecting trunks. According to Poirier,
Cuneo and Delamare,1 one group of deep collecting trunks accompanies the portal
vein, there being fifteen to eighteen of them emerging from the transverse fissure.
They empty into the glands of the hilum. Another group accompanies the hepatic
veins. There are five or six trunks which pass through the Diaphragm and ter-
minate in the glands about the postcava (intrathoracic glands). According to the
above-cited authorities, the superficial trunks of the superior surface are divided
into posterior, anterior, and superior trunks. Some of the posterior trunks ter-
minate in the glands about the coeliac axis, others in the glands about the lower
portion of the postcava in the thorax; others in the glands about the abdominal
portion of the oesophagus. The anterior trunks which are limited to the right
lobe pass to the glands of the hilum. The superior trunks ascend in the suspen-
sory ligament. Some pass to the glands about the postcava, just above the
Diaphragm; others to the hepatic glands. The balance unite to form a very large
trunk, which passes through the Diaphragm and divides into branches which enter
the glands back of the base of the ensiform cartilage.
Nerves of the Liver. — The nerves of the liver are derived from the left vagus
and the solar plexus of the sympathetic. The branches of the vagus ascend from
in front of the stomach within the lesser omentum. The sympathetic nerves pass
along the hepatic artery from the coeliac plexus. The nerves enter the liver at
the transverse fissure and accompany the vessels and ducts to the interlobular
spaces. Here, according to Korolkow, the myelinic fibres are distributed almost
exclusively to the coats of the blood-vessels; while the amyelinic fibres enter the
lobules and ramify between the cells.
The Excretory Apparatus of the Liver.
The excretory apparatus of the liver consists of (1) the hepatic duct, which,
as we have seen, is formed by the junction of the two main ducts, which pass
out of the liver at the transverse fissure, and are formed by the union of the bile-
capillaries; (2) the gall-bladder, which serves as a reservoir for the bile; (3) the
1 The Lymphatics. Translated and edited by Cecil H. Leaf.
1350
THE ORGANS OF DIGESTION
cystic duct, which is the duct of the gall-bladder; and (4) the common bile-duct,
formed by the junction of the hepatic and cystic ducts.
The Hepatic Duct (ductus hepaticus) (Figs. 961, 967, and 969).— Two main
trunks of nearly equal size issue from the liver at the transverse fissure, one from
the right, the other from the left lobe; these unite to form the hepatic duct, which
then passes downward and to the right for about an inch and a half or two
inches, between the layers of the lesser omentum, where it is joined at an acute
angle by the cystic duct, and so forms the ductus communis choledochus. The
hepatic duct, as it descends from the transverse fissure of the liver, between the
two layers of the lesser omentum, lies in company with the hepatic artery and
portal vein (Fig. 957).
The Gall-bladder (vesica fellea) (Figs. 872, 874, 951, 957, and 966).— The
gall-bladder is the reservoir for the bile; it is a conical or pear-shaped musculo-
membranous sac, lodged in a fossa on the under surface of the right lobe of the
liver, and fixed in it by connective tissue, and extending from near the right
extremity of the transverse fissure to the anterior border of the organ. It is
about four inches in length, one inch in breadth at its widest part, and holds from
eight to ten drachms. It is divided into a fundus, body, and neck. The fundus
(fundus vesicae felleae), or broad extremity, is
directed downward, forward, and to the right,
and projects beyond the anterior border of the
liver; the body (corpus vesicae felleae) and neck
(collum vesicae felleae} are directed upward and
backward to the left. The neck of the gall-
bladder is on a slightly higher level than the
lowest point of the gall-bladder; thus the weight
of the bile is away from rather than toward
the outlet. The upper surface of the gall-
bladder is attached to the liver by connective
tissue and vessels. The under surface is
covered by peritoneum, which is reflected on to
it from the surface of the liver. Occasionally
the whole of the organ is invested by the ser-
ous membrane, and is then connected to the
liver by a kind of mesentery.
Relations. — The body of the gall-bladder is
in relation, by its upper surface, with the
liver, to which it is connected by areolar tissue
and vessels ; by its under surface, with the
commencement of the transverse colon ; and
farther back, with the upper end of the de-
scending portion of the duodenum or some-
times with the pyloric end of the stomach or
the first portion of the duodenum. The fundus
is completely invested by peritoneum ; it is in
relation, in front, with the abdominal parietes,
FIG. 966— The gaii-biadder and bile-ducts, immediately below the ninth costal cartilage;
cut through. (Spalteholz.) . J . .
behind, with the transverse arch ot the colon.
The neck is narrow, and curves upon itself like the letter S; at its point of
connection with the cystic duct it presents a well-marked constriction.
When the gall-bladder is distended with bile or filled with calculi, the fundus may be felt
through the abdominal parietes, especially in an emaciated subject; the relations of this sac will
also serve to explain the occasional occurrence of abdominal biliary fistulae, through which biliary
calculi may pass out, and of the passage of calculi from the gall-bladder into the stomach, duod-
enum, or colon, which occasionally happens.
THE EXCRETORY APPARATUS OF THE LIVER
1351
Structure. — The gall-bladder consists of three coats — serous, fibrous and mus-
cular, and mucous.
The External or Serous Coat (tunica serosa vesicae felleae) is derived from the peri-
toneum; it completely invests the fundus, but covers the body and neck only on
their under surfaces.
The Fibro -muscular Coat (tunica muscularis vesicae felleae) is a thin but strong
layer which forms the framework of the sac, consisting of dense fibrous tissue which
interlaces in all directions and is mixed with plain muscular fibres which are dis-
posed chiefly in a longitudinal direction, a few running transversely.
The Internal or Mucous Coat (tunica mucosa vesicae felleae) is loosely connected
with the fibrous layer. It is generally tinged with a yellowish-brown color, and
is everywhere elevated into minute rugae, by the union of which numerous meshes
are formed, the depressed intervening spaces having a polygonal outline. The
meshes are smaller at the fundus and neck, being most developed about the centre
of the sac. Opposite the neck of the gall-bladder the mucous membrane projects
inward in the form of oblique ridges or folds, forming a sort of screw-like or spiral
valve (Fig. 966).
The mucous membrane is covered with columnar epithelium, and secretes an
abundance of thick viscid mucus; it is continuous through the hepatic duct with
the mucous membrane lining the ducts of the liver, and through the ductus com-
munis choledochus with the mucous membrane of the duodenum.
The Cystic Duct (ductus cysticus). — The cystic duct, the smallest of the three
biliary ducts, is about an inch and a half in length. It passes obliquely downward
and to the left from the neck of the gall-bladder, and joins the hepatic duct to form
the common bile-duct. It lies in the gastro-hepatic ornentum in front of the portal
--% GALL-BLADDER
_\ _ HEPATIC
DUCT
COMMON
DUCT
SPHINCTER OF
COMMON DUCT
PANCREATIC
DUCT
AMPULLA
OF VATER
WALL OF
DUODENUM
Fir,. 967. — The biliary ducts. (Schematic.)
(Poirier and Charpy.)
FIG. 968. — The sphincter of the common bile-duct.
(Poirier and Charpy.)
vein, the hepatic artery lying to its left
side. The mucous membrane lining its in-
terior is thrown into a series of crescentic
folds, from five to twelve in number, similar
to those found in the neck of the gall-blad-
der. They project into the duct in regular
succession, and are directed obliquely round
the tube, presenting much the appearance
of a continuous spiral valve (valvula spiralis
[Heisteri]) (Fig. 966). When the duct is
distended, the spaces between the folds
are dilated, so as to give to its exterior
a sacculated appearance.
The Ductus Communis Choledochus or
Common Bile-duct (ductus choledochus)
Figs. 966 and 967) , the largest of the three,
1352
THE ORGANS OF DIGESTION
is the common excretory duct of the liver and gall-bladder. It is about three
inches in length, is of the diameter of a goose-quill, and is formed by the junction
of the cystic and hepatic ducts.
It descends within the two layers and along the right border of the lesser omen-
turn behind the first portion the duodenum, in front of the portal vein, and to the
right of the hepatic artery (Fig. 872); then passes either between the pancreas
and descending portion of the duodenum, or through the head of the pancreas.
In fifty-eight dissections Prof. Biingner found that it passed through the pan-
creas fifty-five times and over the head only three times. Even when it "passes
through the pancreas it almost always joins the pancreatic duct outside of the
gland. It descends by the right side of the pancreatic duct and passes with it
obliquely through the wall of the descending portion of the duodenum between
the mucous and muscular coats in the submucous tissue for one-half to three-
CIRCULAR
MUSCULAR
FIBRES
MUCOUS
COAT
LONGITUDINAL
MUSCULAR FIBRES
ACCESSORY
PANCREATIC
DUCTS
BILE-DUCT
PANCREATIC
DUCT
FIG. 970. — Diagram showing the bile
and pancreatic ducts piercing the wall of
the duodenum obliquely. (Cunningham.)
quarters of an inch. The two
ducts usually unite just before
opening into the duodenum
(Figs. 967, 968, and 970), but
may remain independent
throughout (in about 10 per
cent, of individuals). The
diverticulum ampulla of Vater
(Fig. 967) is the conical cavity
formed by the fusion of the
two ducts, and is much larger
than the opening on the bile-
papilla. It averages 3.9 mm.
in length. The average 'diameter of the orifice is 2.5 mm. (Opie). The two
ducts open by a common orifice if there is an ampulla, or by two separate orifices
if there is no ampulla, upon the summit of a papilla, situated at the inner side of
the descending portion of the duodenum, a little below its middle and about three
or four inches below the pylorus. Circular muscular fibres, continuous with the
longitudinal fibres of the ducts, surround the termination of the two ducts in the
ampulla. These fibres constitute the so-called sphincter of Oddi (Fig. 968).
Structure. — The coats of the large biliary ducts are an external or fibrous and an
internal or mucous. The fibrous coat is composed of strong fibro-areolar tissues,
with a certain amount of muscular tissue arranged, for the most part, in a circular
manner around the duct. The mucous coat is continuous with the lining mem-
FIG. 969. — Part of the bile-duct and the pancreatic ducts. C
and B, calculi; Sa, Santorini's duct; P, pancreatic duct; /// and
IV, ducts from the right and left lobes of the liver; //, cystic duct;
C, gall-bladder; A, common duct. (Robinson.)
THE EXCRETORY APPARATUS OF THE LIVER 1353
brane of the hepatic ducts and gall-bladder, and also with that of the duode-
num; and, like the mucous membrane of these structures, its epithelium is of the
columnar variety. It is provided with numerous mucous glands, which are lobu-
lated and open by minute orifices scattered irregularly in 'the larger ducts. It is
questionable if the smallest biliary ducts, which lie in the interlobular spaces, have
any coats. Heidenhain thinks they have a connective-tissue coat, in which are
muscle-cells arranged both circularly and longitudinally, and an epithelial layer,
consisting of short columnar cells.
Dimensions of the Bile-ducts. — The hepatic duct is about two inches in length,
and its lumen is one-sixth of an inch in diameter. The cystic duct is about one
and one-half inches in length, and its lumen is one-twelfth of an inch in diameter.
The common duct is about three inches in length, and its lumen is one-quarter of
an inch in diameter. The duodenal opening is smaller than the common duct.
The ducts are capable of considerable distention, but the duodenal opening can-
not be dilated (Hyrtl)..
Blood-vessels, Lymphatics, and Nerves of the Gall-bladder and Bile-ducts. — The
cystic artery (Fig. 421), a branch from the right division of the hepatic, supplies the
gall-bladder and cystic duct with blood. It passes along the cystic duct, and on
reaching the gall-bladder divides into an upper branch and a lower branch. The
upper branch lies between the gall-bladder and the liver and sends branches to each.
The lower branch is between the peritoneum and the wall of the gall-bladder.
The cystic veins empty into the portal vein. The common duct receives branches
from the superior pancreatico-duodenal artery. There is a submucous lymphatic net-
work and a muscular lymphatic network. The lymphatics are much less numer-
ous at the fundus of the gall-bladder than at the neck or in the extra-hepatic ducts.
The collecting trunks (Fig. 504) end in glands along the cystic and common ducts
and these glands are in communication with the duodenal lymphatics and the
lymphatics from the head of the pancreas. The nerves of the gall-bladder and
bile-ducts come from the coeliac plexus of the sympathetic. The adjacent peri-
toneum is plentifully supplied with nerves (Robinson).
The Bile (fel) . — The bile is a reddish-brown or greenish fluid. It contains pig-
ments (bilirubin and biliverdin), fats and soaps, cholesterin, sodium salts of glyco-
cholic and taurocholic acid, lecithin, and nucleo-albumin furnished by the mucous
membrane. There are also present CO2; chlorides, carbonates, phosphates, and
sulphates of the alkalies and of calcium, and iron. The amount normally
secreted is from one pint to one and one-half pints in the twenty-four hours.
Surface Relations. — The liver is situated in the right hypochondriac and the epigastric
regions, and is moulded to the arch of the Diaphragm. In the greater part of its extent it lies
under cover of the lower ribs and their cartilages, but in the epigastric region it comes in con-
tact with the abdominal wall, in the subcostal angle. The upper limit of the right lobe of the
liver may be defined in the middle line by the junction of the mesosternum with the ensiform
cartilage; on the right side the line must be carried upward as far as the fifth rib cartilage
in the line of the nipple and then downward to reach the seventh rib at the side of the chest.
The upper limit of the left lobe may be defined by continuing this line to the left with an inclina-
tion downward to a point about two inches to the left of the sternum on a level with the sixth
left costal cartilage. The lower limit of the liver may be indicated by a line drawn half an inch
below the lower border of the thorax on the right side as far as the ninth right costal cartilage,
and thence obliquely upward across the subcostal angle to the eighth left costal cartilage. A
slight curved line with its convexity to the left from this point— i. e., the eighth left costal
cartilage— to the termination of the line indicating the upper limit will denote the left margin of
the liver. The fundus of the gall-bladder approaches the surface behind the anterior extremity
of the ninth costal cartilage, close to the outer margin of the Right rectus muscle.
It must be remembered that the liver is subject to considerable alterations in position, and
the student should make himself acquainted with the different circumstances under which this
occurs, as they are of importance in determining the existence of enlargement or other diseases
of the organ.
1354 THE ORGANS OF DIGESTION
Its position varies according to the posture of the body. In the erect position in the adult
male the edge of the liver projects about half an inch below the lower edge of the right costal
cartilages, and its anterior border can be often felt in this situation if the abdominal wall is thin.
In the supine position the liver gravitates backward and recedes above the lower margin of the
ribs, and cannot then be detected by the finger. In the prone position it falls forward, and can
then generally be felt in a patient with loose and lax abdominal walls. Its position varies also
with the ascent or descent of the Diaphragm. In a deep inspiration the liver descends below
the ribs; in expiration it is raised behind them. Again, in emphysema, where the lungs are
distended and the Diaphragm descends very low, the liver is pushed down; in some other dis-
eases, as phthisis, where the Diaphragm is much arched, the liver rises very high up. Pressure
from without, as in tight lacing, by compressing the lower part of the chest, displaces the liver
considerably, its anterior edge often extending as low as the crest of the ilium; and its convex
surface is often at the same time deeply indented from the pressure of the ribs. Again, its posi-
tion varies greatly according to the greater or less distention of the stomach and intestines.
When the intestines are empty the liver descends in the abdomen, but when they are distended
it is pushed upward. Its relations to surrounding organs may also be changed by the growth of
tumors or by collections of fluid in the thoracic or abdominal cavities.
Surgical Anatomy. — Movable liver or hepatoptosis is a rare condition, in which the liver
moves or can be moved from its normal position. It is due to lessened tone of the abdominal
muscles and relaxation of the liver supports. In movable liver the organ may be rotated on its
vertical axis or on its transverse axis. Tongue-like lobes have been referred to. On account of
its large size, its fixed position, and its friability, the liver is more frequently ruptured than
any of the abdominal viscera. The rupture may vary considerably in extent, from a slight
scratch to an extensive laceration completely through its substance, dividing it into two parts.
Sometimes an internal rupture without laceration of the peritoneal covering takes place, and
such injuries are most susceptible of repair; but small tears of the surface may also heal; when,
however, the laceration is extensive, death usually takes place from hemorrhage, on account
of the fact that the hepatic veins are contained in rigid canals in the liver-substance and are
unable to contract, and are moreover unprovided with valves. The liver may also be torn
by the end of a broken rib perforating the Diaphragm. The liver may be injured by stabs
or other punctured wounds, and when these are inflicted through the chest-wall both pleural
and peritoneal cavities may be opened up and both lung and liver be wounded. In cases of
wound of the liver from the front, protrusion of a part of this viscus may take place, but can gen-
erally easily be replaced. In cases of laceration of the liver, when there is evidence that bleeding
is going on, the abdomen must be opened, the laceration sought for, and the bleeding arrested.
This may be done temporarily by introducing the forefinger into the foramen of Winslow and
placing the thumb on the gastro-hepatic omentum and compressing the hepatic artery and portal
vein between the two. Any bleeding points can then be seen. Bleeding is, if possible, arrested
by suture ligatures. The edges of a small laceration are simply brought together and sutured by
means of a blunt, curved, round needle passed from one side of the wound to the other. All sutures
must be passed before any are tied, and this must be done with the greatest gentleness, as the liver
substance is very friable. If suture fails the actual cautery may succeed. When the laceration is ex-
tensive, the liver is sutured to the abdominal wall to hold it firm when pressure is applied, and then
the laceration is packed with a piece of iodoform gauze, the end of which is allowed to hang out
of the external wound. Abscess of the liver is of not infrequent occurrence, and may open in many
different ways on account of the relations of this viscus to other organs. Thus it may burst into
the lung, the pus being coughed up, or into the stomach; the pus perhaps being vomited, it may
burst into the colon or into the duodenum, or, by perforating the Diaphragm, it may empty
itself into the pleural cavity. Frequently it makes its way forward, and points on the anterior
abdominal wall, and finally it may burst into the peritoneal or pericardiac cavity. Abscesses
of the liver require opening, and this must be done by an incision in the abdominal wall, in the
thoracic wall, or in the lumbar region, according to the direction in which the abscess is tracking.
The incision through the abdominal wall is to be preferred when possible. The abdominal wall
is incised over the swelling, and unless the peritorieum is adherent, gauze is packed all around
the exposed liver surface and the abscess opened, if deeply seated, preferably by the thermo-
' cautery. Hydatid cysts are more often found in the liver than in any other of the viscera. The
reason of this is not far to seek. The embryo of the egg of the tsenia echinococcus being liberated
in the stomach by the disintegration of its shell, bores its way through the gastric walls and
usually enters a blood-vessel, and is carried by the blood-stream to the hepatic capillaries, where
its onward course is arrested, and where it undergoes development into the fully formed hydatid.
Tumors of the liver have recently been subjected to surgical treatment by removal of a portion
of the organ. The abdomen is opened and the diseased portion of liver exposed; the circulation
is controlled by compressing the portal vein and the hepatic artery in the gastro-hepatic omen-
tum and a wedge-shaped portion of liver containing the tumor removed; the divided vessels
are ligated and the cut surfaces brought together and sutured in the manner directed above.
When the gall-bladder or one of its main ducts is ruptured, which may occur independently
of laceration of the liver, death usually occurs from peritonitis. If the symptoms have led to
THE PANCREAS 1355
the performance of a laparotomy and a small rent is found, it should be sutured; if an exten-
sive opening is found the gall-bladder should be removed. If the cystic duct is torn, its intes-
tinal end must be closed and the gall-bladder removed. In rupture of either of the other
ducts, simply provide for free drainage.
The gall-bladder may become distended with bile in cases of obstruction of its duct or of the
common bile-duct, or it may become distended from a collection of gall-stones within its interior,
thus forming a large tumor. The swelling due to distention with bile is pear-shaped, and pro-
jects downward and forward to the umbilicus. It moves with respiration, since it is attached to
the liver. To relieve a patient of gall-xfom's, the gall-bladder must be opened and the gall-stones
removed. The operation is performed by an incision two or three inches long in the right semi-
lunar line, commencing at the costal margin. The peritoneal cavity is opened, and, the tumor
having been found, gauze pads are packed around it to protect the peritoneal cavity, and it is
aspirated. When the contained fluid has been evacuated the flaccid bladder is drawn out of
the abdominal wound and its wall incised to the extent of an inch; any gall-stones in the
bladder are now removed and the interior of the sac sponged dry. If the case is one of
obstruction of the duct, an attempt must be made to dislodge the stone by manipulation through
the wall of the duct; or it may be crushed from without by the fingers or carefully padded for-
ceps. If this does not succeed, the safest plan is to incise the duct, extract the stone, close
the incision in the duct by fine sutures in two layers and employ drainage. After all obstruction
has been removed, four courses are open to the surgeon: 1. The wound in the gall-bladder
may be at once sewed up, the organ returned into the abdominal cavity, and the external incision
closed. 2. The edges of the incision in the gall-bladder may be sutured to the fascia of the ex-
ternal wound, and a fistulous communication established between the gall-bladder and the exte-
rior; this fistulous opening usually closes in the course of a few weeks. 3. The gall-bladder may
be connected with the intestinal canal, preferably the duodenum, by. means of a lateral anasto-
mosis; this is known as cholecystenterostomy. 4. The gall-bladder may be completely removed
(cholecystectomy). Plan 2 is usually followed. Plan 4 is employed when the coats of the
gall-bladder are seriously diseased. Plan 2 is employed in obstruction of the common duct by
malignant disease.
If a stone blocks the diverticulum of Vater and if the common bile-duct and the pancreatic
duct empty into the diverticulum, it is evident that both ducts will be blocked. It has been
demonstrated that in such a case the pressure urging the bile onward is sufficient to overcome
the pressure in the pancreatic duct and drive bile into the ducts of the pancreas, the result,,
perhaps, being disastrous inflammation of the pancreas.
. Septic trouble arises more rapidly when a stone is blocked in the duct than when stones merely
block the gall-bladder, because the first-named part is richer in lymphatics (Murphy).
THE PANCREAS (Figs. 971, 972, 973, 974).
Dissection. — The pancreas may be exposed for dissection in three different ways: 1. By
raising the liver, drawing down the stomach, and tearing through the gastro-hepatic omentum
and the ascending layer of the transverse mesocolon. 2. By raising the stomach, the arch of
the colon, and great omentum, and then dividing the inferior layer of the transverse mesocolon
and raising its ascending layer. 3. By dividing the two layers of peritoneum, which descend
from the great curvature of the stomach to form the great omentum; turning the stomach
upward, and then cutting through the ascending layer of the transverse mesocolon (see Fig. 866).
The Pancreas (xav-xpeaz, all flesh) is a compound racemose gland, analo-
gous in its structure to the salivary glands, though softer and less compactly
arranged than those organs. It is long and irregularly prismatic in shape, and
has been compared to a human or a dog's tongue ; it is of reddish-white color.
Its right extremity being broad, is called the head. The right half of the head
above is continuous with the neck, which connects the head to the main portion
of the organ, the body. The neck is a slight constriction or thin part of the gland,
placed in front of the portal vein, and connecting the head to the body. The left
half of the head is separated from the neck by a notch, the incisura pancreaticus.
The body of the gland gradually tapers into an extremity directed to the left, and
called the tail. The pancreas is placed transversely across the posterior wall of
the abdomen, at the back of the epigastric and left hypochondriac regions. Its
length varies from five to six inches, its breadth is an inch and a half, and its thick-
ness from half an inch to an inch, being greater at its right extremity and along
1356
THE ORGANS OF DIGESTION
its upper border. Its weight varies from two to three and a half ounces, but it
may reach six ounces.
HEPATIC DUCT
CYSTIC DUCT
CANAL OF
SANTORINI
SUPERIOR MESENTERIC VEIN
FIG. 971. — Position and relations of pancreas.
Gastric artery
Lower end of oesophagus.
Inferior mesenteric
artery.
tpcrior mesenteric
artery.
Spermatic vessels.
FIG. 972. — The duodenum and pancreas. The liver has been lifted up and the greater part of the stomach
removed: a} portal vein; 6, hepatic duct; c, cystic duct; d, hepatic artery; e, right suprarenal capsule;
/, pyloric orifice ; g, right gastro-epiploic artery ; h, superior mesenteric vein ; i, left crus of diaphragm ; j, left
suprarenal capsule ; k, splenic vein ; /, splenic artery; m, duodeno-jejunal junction ; A, B, c, D, the four portions
of the duodenum. (Testut.)
THE PANCREAS 1357
The Right Extremity or Head of the Pancreas (caput pancreatis) (Fig. 971)
is shaped like the head of a hammer, being elongated both above and below; it
is flattened from before backward, and conforms to the whole concavity of the
duodenum, which is slightly overlapped by it. The anterior surface near its left
border exhibits a notch, the incisura pancreatis, which contains the superior mesen-
teric vessels. The notch marks the separation of the inferior portion of the head,
which is known as the uncinate process of Winslow (processus uncinatus [Winslowi]) ,
which rests, below, upon the inferior portion of the duodenum, and, above, is
pushed up back of the upper portion. The lower end of the head is crossed by
the transverse colon and its mesocolon. Behind, the head of the pancreas is in
relation with the postcava, the left renal vein, the right crus of the Diaphragm,
and the aorta. The common bile-duct descends behind, between the duodenum
and pancreas, or in the substance of the gland; and the pancreatico-duodenal
artery descends in front between the same parts. The head of the pancreas is
closely adherent to the duodenum.
FIG. 973. — Duodenal orifice of the pancreatic duct and of the canal of Santorini.
The Neck of the Pancreas is about an inch long, and passes upward and for-
ward to the left, having the first part of the duodenum above it, and the ter-
mination of the fourth portion below. It lies in front of the commencement of
the portal vein, and is grooved on the right by the gastro-duodenal and superior
pancreatico-duodenal arteries. The pylorus lies just above it.
The Body (corpus pancreatis) and Tail (cauda pancreatis) of the Pancreas are
somewhat prismatic in shape, and have three surfaces: anterior, posterior, and
inferior.
The Anterior Surface (fades anterior). — The anterior surface is somewhat con-
cave, and is covered by the posterior surface of the stomach which rests upon it,
the two organs being separated by the lesser sac of the peritoneum. At its right
extremity there is a well-marked prominence, called by His the omental tuberosity
(tuber omentale).
The Posterior Surface (fades posterior). — The posterior surface is separated from
the vertebral column by the aorta, the splenic vein, the left kidney and its vessels,
the left suprarenal capsule, the pillars of the Diaphragm, and the origin of the
superior mesenteric artery.
The Inferior Surface (fades inferior) (Fig. 972). — The inferior surface is narrow,
and lies upon the duodeno-jejunal flexure and on some coils of the jejunum; its left
extremity rests on the splenic flexure of the colon.
The Superior Border (margo superior) (Fig. 972). — The superior border of the
body is blunt and flat to the right; narrow and sharp to the left, near the tail. It
commences to the right in the omental tuberosity, and is in relation with the
coeliac axis, from which the hepatic artery courses to the right just above the gland,
while the splenic branch runs in a groove along this border to the left.
1358
THE ORGANS OF DIGESTION
The Anterior Border (margo anterior). — The anterior border is the position where
the two layers of the transverse mesocolon separate; the one passing upward in
front of the anterior surface, the other backward below the inferior surface
(Fig. 866).
The lesser end or tail of the pancreas is narrow; it extends to the left as far as
the lower part of the inner aspect of the spleen, and its end is directed upward and
to the left (Fig. 972).
Birmingham describes the body of the pancreas as projecting forward as a
prominent ridge into the abdominal cavity and forming a sort of shelf on which the
stomach lies. He says: "The portion of the pancreas to the left of the middle line
has a very considerable antero-posterior thickness ; as a result the anterior surface
is of considerable extent, it looks strongly upward, and forms a large and important
part of the shelf. As the pancreas extends to the left toward the spleen it crosses
the upper part of the kidney, and is so moulded on to it that the top of the kidney
forms an extension inward and backward of the upper surface of the pancreas and
extends the bed in this direction. On the other hand, the extremity of the pan-
creas comes in contact with the spleen in such a way that the plane of its upper
surface runs with little interruption upward and backward into the concave gastric
surface of the spleen, which completes the bed behind and to the left, and, running
upward, forms a partial cap for the wide end of the stomach."1 An occasional
anomaly is a pancreas prolonged in front of the duodenum or actually embracing
it (annular pancreas).
RECTUS MUSCLE.
f8th Costal Cartilage.
7th Costal Cartilage.
7th Rib.
8th Rib.
—9th Rib.
DIAPHRAGM.
Abdominal Aorta.
mhRib. nth Rib.
FIG. 974. — Transverse section through the middle of the first lumbar vertebra, showing the relations of the
pancreas. (Braune.)
Peritoneal Relations (Fig. 866). — The transverse mesocolon is attached to the
anterior border of the pancreas, from the tail to the neck of the gland, and the two
layers of the mesocolon separate. The anterior layer which comes from the lesser
peritoneum covers part of the anterior surface and the superior surface; the poste-
rior layer, which comes from the greater omentum, covers the rest of the anterior
surface and the inferior surface. The posterior surface is devoid of peritoneum.
1 Journal of Anatomy and Physiology, vol. xxxi., part L, p. 102.
THE PANCREAS 1359
There is in front of the head and at the anterior margin a narrow strip of pancreas,
which remains uncovered by peritoneum and which corresponds to the cellular
tissue of the mesocolon.
The principal excretory duct of the pancreas, called the pancreatic duct or canal
of Wirsung (ductus pancreaticus [Wirsungi]) (Figs. 969, 971, and 973), from its
discoverer, extends transversely from left to right through the substance of the
pancreas. In order to expose it, the superficial portion of the gland must be
removed. It commences by the junction of the small ducts of the lobules situated
in the tail of the pancreas, and, running from left to right through the body, it con-
stantly receives the ducts of the various lobules composing the gland. Consider-
ably augmented in size, it reaches the neck, and turning obliquely downward, back-
ward, and to the right, it comes into relation with the common bile-duct, lying to
its left side; leaving the head of the gland, it passes very obliquely through the
mucous and muscular coats of the duodenum, and usually terminates by an orifice
common to it and the ductus communis choledochus upon the summit of an ele-
vated papilla, situated at the inner side of the descending portion of the duodenum,
three or four inches below the pylorus (Figs. 967, 968, and 970).
Sometimes the pancreatic duct and ductus communis choledochus open sep
rately into the duodenum (Fig. W)6):* In about one-fifth of the subjects there is an
accessory duct, which is given off from the canal of Wirsung in the neck of the pan- /O
creas and passes horizontally to the right to open into the duodenum about an
inch above the orifice of the main duct. This is known as the duct of Santorini
(ductus pancreaticus accessorius [Santorini]) (Figs. 969. 970, and 973).
The pancreatic duct, near the duodenum, is about the size of an ordinary quill;
its walls are thin, consisting of two coats, an external fibrous and an internal
mucous ; the latter is smooth, and furnished near its termination with a few scat-
tered follicles.
Structure. — In structure, the pancreas resembles the salivary glands. It differs
from them, however, in certain particulars, and is looser and softer in its texture.
It is not enclosed in a distinct capsule, but is surrounded by areolar tissue, which
dips into its interior, and connects together the various lobules of which it is com-
posed. Each lobule, like the lobules of the salivary glands, consists of one of the
ultimate ramifications of the main duct, terminating in a number of caecal pouches
or alveoli, which are tubular and somewhat convoluted. The minute ducts con-
nected with the alveoli are narrow and lined with flattened cells. They are the
secreting end tubules. The narrow ducts which come from the end tubules are
lined with flat epithelial cells. The alveoli are almost completely filled with secret-
ing cells, so that scarcely any lumen is visible. In the centre of the end tubules
flat cells are frequently found. They are continuations into the tubules of the
duct epithelium. These cells are known as the centro-acinar cells of Langerhans.
The true secreting cells which line the wall of the alveolus are very characteristic.
They are columnar or rounded in shape and present two zones: an outer one
clear and finely striated next the basement-membrane, and an inner granular
one next the lumen. The highly refracting granules are known as zymogen
granules. During digestion the granules gradually disappear and the cells become
clear. During fasting the granular zone occupies more than one-half of the cell
(Szymonowicz). In some secreting cells of the pancreas is a spherical mass,
staining more easily than the rest of the cells; this is termed the paranucleus, and
is believed to be an extension from the nucleus. The connective tissue among the
gland tubules and alveoli presents in certain parts collections of cells, which are
termed inter-alveolar cell-islets, intertubular cell-masses or islands of Langerhans.
Opie points out that they are most common in the splenic end of the pancreas.
The cells of the islands are smaller than the secreting cells of the alveoli, and
are arranged in layers with intervening spaces. The islands are surrounded by
1360 THE ORGANS OF DIGESTION
fine connective tissue. The spaces in the islands contain capillaries. There
are no ducts in the islands of Langerhans. Their function is to furnish the
internal secretion of the pancreas.
Blood-vessels, Lymphatics, and Nerves. — The arteries of the pancreas come from
the superior pancreatico -duodenal branch of the gastro -duodenal; the inferior pan-
creatico -duodenal branch of the superior mesenteric; the inferior pancreatic branch of
the superior mesenteric; pancreatic branches of the hepatic and pancreatic branches
of the splenic. In a few cases a large artery, the pancreatica magna, accompanies
the pancreatic duct. In most cases there is no such vessel. The veins are the
anterior pancreatico -duodenal branch of the superior mesenteric; the posterior pancre-
atico-duodenal branch and other pancreatic branches of the portal; and pancreatic
branches of the splenic. The lymphatics arise in a network about the lobules.
Numerous collecting trunks pass to the surface of the pancreas, anastomose with
each other, and enter into glands about the pancreas. The splenic glands receive
most of the trunks. Others are received by glands along the aorta (Sappey),
glands at the origin of the superior mesenteric artery, and glands along the pan-
creatico-duodenal vessels.1 The nerves come from the coeliac, superior mesenteric,
and splenic plexuses.
The Pancreatic Juice. — The pancreatic juice is a clear, somewhat viscid alkaline
liquid. Its specific gravity is about 1030. The solid .matter consists chiefly of
proteids, and amounts to about 10 per cent, of a sample of the juice.2 The juice
contains a ferment which breaks up fat, a ferment which converts starch into
sugar, a ferment which curdles milk, and a ferment which digests proteid material.
Surface Form. — The pancreas lies in front of the second lumbar vertebra, and can some-
times be felt, in emaciated subjects, when the stomach and colon are empty, by making deep
pressure in the middle line about three inches above the umbilicus.
Surgical Anatomy. — Of late years our knowledge of the structure, functions, and diseases
of the pancreas has been notably increased, and surgeons have begun to operate for certain
pancreatic diseases. It is occasionally the seat of cancer, which usually affects the head or
duodenal end, and therefore often speedily involves the common bile-duct, leading to persistent
jaundice. Cancer of the pancreas may be primary or secondary. Primary sarcoma is very
unusual; secondary sarcoma is more common, but cancer is far commoner than either form of
sarcoma. Adenoma may also occur. Cases are on record of the successful removal of tumors of
the pancreas, but the operations are very dangerous, are extremely difficult, and are seldom
attempted. The pancreas may be the seat of syphilitic or tuberculous disease. As a result of
pancreatic injury, there may be effusion into the lesser peritoneal cavity. The lesser cavity
becomes distended, and the fluid of this pseudo-cyst may contain pancreatic juice (Jordan Lloyd).
True cysts of the pancreas are occasionally found. Pancreatic cysts may result from blocking
of the duct, from epithelial proliferation, from traumatism and hemorrhage, or from hydatid dis-
ease. Congenital cysts may occur, and cystic carcinoma is sometimes encountered. Cysts of the
pancreas may present in the epigastric region above and to the right of the umbilicus. The
fluid in these cysts contains some of the pancreatic secretion. A pancreatic cyst is best treated
by opening the abdomen, suturing the cyst to the skin, opening the cyst and providing for drainage.
Complete extirpation of the cyst is invariably difficult and is usually impossible. It has been
said that the pancreas is the only abdominal viscus which has never been found in a hernia! pro-
trusion; but even this organ has been found, in company with other viscera, in rare cases of
diaphragmatic hernia. The pancreas has been known to become invaginated into the intestine,
and portions of the organ have sloughed pff. In cases of excision of the pylorus great care must
be exercised to avoid wounding the pancreas, as the escape of the pancreatic fluid may be attended
with serious and even with fatal results, peritonitis and fat necrosis, and gangrene being caused.
Rupture of the pancreas as a solitary result of traumatism is very unusual, but is more common
in violent injuries which rupture the liver and spleen as well. An injury which lacerates the
pancreas and permits blood and pancreatic juice to flow into the lesser peritoneal cavity is usually
rapidly fatal, but may not be. The foramen of Winslow may be occluded by inflammation, and
a pseudo-cyst may form. In severe laceration of the pancreas alone, it would be proper to open
the abdomen, ligature bleeding vessels, suture the pancreas, and drain the lesser peritoneal cavity
posteriorly. A gunshot wound of the pancreas requires posterior drainage. Every effort must
1 Poirier, Cun6o, and Delamare on the Lymphatics. Edited and translated by Cecil H. Leaf.
* Robson and Moyniham on Diseases of the Pancreas.
THE SPLEEN
1361
be made in a pancreatic wound to rapidly get rid of pancreatic fluid by drainage from jthe
wound area, as this fluid is extremely irritant and may cause gangrene.
Inflammation of the pancreas is due to infection. Occasionally it seems to follow the entrance
of bile into the pancreatic duct, because of plugging of the ampulla with a calculus (Halsted,
Opie). Hemorrhage into the pancreas is frequent in acute pancreatitis, and fat necrosis is common
in the fat of the mesentery, subperitoneal tissue, omentum, and other parts. Acute pancreatitis
may be recovered from if the abdomen is opened, the pancreas incised, and drainage employed.
In chronic interstitial pancreatitis of the head of the pancreas the gall-duct is apt to become
blocked, and the disease is frequently mistaken for cancer. Cure may follow opening and drain-
age of the gall-bladder.
• THE SPLEEN (LIEN) (Figs. 971, 972, 974).
The spleen belongs to that class of bodies which are known as ductless glands.
It is probably related to the blood-vascular system, but in consequence of its
anatomical relationship to the stomach and its physiological relationship to the
liver it is convenient to describe it in this section. It is situated principally in the
posterior portion 'of the left hypochondriac region, its upper and inner extremity
extending into the epigastric region; lying between the fundus of the stomach
and the Diaphragm. If the abdomen is opened a spleen of ordinary size is not
visible from the front, as it is placed between the left kidney, Diaphragm, and
stomach. It moves with the respiratory movements and with the movements of
the stomach. It is the largest of the so-called ductless glands, and varies greatly
in size. Usually it measures some five inches in length. It is of an oblong,
flattened form, soft, of very brittle consistence, highly vascular, and of a dark-
purplish color.
Surfaces. The External or Phrenic Surface (Jades diaphragmatica). — The exter-
nal or phrenic surface is convex, smooth, and is directed upward, backward, and
to the left, except at its upper end, where it is directed slightly inward. It is in
relation with the under surface of the Diaphragm, which separates it from the
eighth, ninth, tenth, and eleventh ribs of the left side, and in part from the lower
border of the left lung and pleura. It is
to be remembered that not only are the
peritoneum and the Diaphragm between
the spleen and the ribs, but also the cavity
of the left pleura and a portion of the left
lung.
The Internal Surface. — The internal sur-
face is concave, and divided by a ridge
into an anterior or larger, and a posterior or
smaller portion.
The Anterior Portion of the internal sur-
face or the gastric surface (fades gastrica),
which is directed forward and inward, is
broad and concave, and is in contact with
the posterior wall of the great end of the
stomach; and below this with the tail of
the pancreas. It presents near its inner
border a long fissure, termed the hilum
(hilus lienis). This is pierced by several
irregular apertures, for the entrance and
exit of vessels and nerves.
The Posterior Portion of the internal
surface or the renal surface (fades renalis]
is directed inward and downward. It is
somewhat flattened, does not reach as high
86
FIG. 975. — The spleen, showing its gastric and
renal surfaces. (Testut.)
1362
THE ORGANS OF DIGESTION
as^the gastric surface, is considerably narrower than the latter, and is in relation
with the upper part of the outer surface of the left kidney and occasionally with
the left suprarenal capsule.
The upper end of the spleen (extremitas superior] is directed inward, toward the
vertebral column, where it lies on a level with the eleventh thoracic vertebra. The
lower end (extremitas inferior) , sometimes termed the basal surface, is flat, triangular
in shape, and rests upon the splenic flexure of the colon and the phreno-colic liga-
ment, and is generally in contact with the tail of the pancreas. The anterior border
(margo anterior) is free, sharp, and thin, and is often notched, especially below. It
separates the phrenic surface from the gastric surface. The posterior border (margo
posterior) is more rounded and blunter than the anterior. It separates the renal
portion of the internal surface from the phrenic surface. It corresponds to the
lower border of the eleventh rib and lies between the Diaphragm and left kidney.
The internal border is the name sometimes given to the ridge which separates the
renal and gastric portions of the internal surface.
The spleen is surrounded by peritoneum, except at the hiluni and the serous
membrane, is firmly adherent to its capsule, and is held in position by two folds
of this membrane: one, the lieno-renal ligament (ligamentum pfyrenicolienale) (Figs.
870 and 873), is derived from the layers of peritoneum forming the greater and
lesser sacs, where they come into contact between the left kidney and the spleen.
Between its two layers the splenic vessels pass; the second, the gastro-splenic
omentum (ligamentum gastrolienale) , also formed of two layers, derived from the
greater and lesser sacs, respectively, where they meet between the spleen and
stomach (Fig. 873). Between these two layers run the vasa brevia of the
splenic artery and vein. ,The spleen is also supported by the phreno-colic ligament
(ligamentum phrenicocolicum) , upon which its lower end rests.
The size and weight of the spleen are liable to very extreme variations at dif-
ferent periods of life, in different individuals, and in the same individual under
different conditions. In the adult, in whom it attains its greatest size, it is usually
FIG. 976. — Transverse section of the spleen, showing the trabecular tissue and the splenic vein and
its tributaries.
about five inches in length, three inches in breadth, and an inch or an inch and a
half in thickness, and weighs about seven ounces. At birth, its weight, in propor-
tion to the entire body, is almost equal to what is observed in the adult, being as
THE SPLEEN 1363
1 to 350; while in the adult it varies from 1 to 320 to 1 to 400. In old age, the organ
not only decreases in weight, but decreases considerably in proportion to the
entire body, being as 1 to 700. The size of the spleen is increased during and
after digestion, and' varies considerably according to the state of nutrition of the
body, being large in highly fed, and small in starved animals. In intermittent
and other fevers it becomes much enlarged, weighing occasionally from eighteen
to twenty pounds.
Frequently in the neighborhood of the spleen, and especially in the gastro-
splenic and great omenta, small nodules of splenic tissue may be found, either
isolated, or connected to the spleen by thin bands of splenic tissue. Every such
nodule is known as a supernumerary or accessory spleen (lien accessorius}. Accessory
spleens vary in size from that of a pea to that of a plum.
Support and Movability of the Spleen. — The spleen is normally movable
within certain narrow limits. It moves with respiration and with stomach move-
ments. It is supported by ligaments (p. 1362). An unduly movable spleen is
called a movable spleen. In order that a spleen shall become unduly movable,
the ligaments must stretch, and this stretching is often effected when the organ
is greatly enlarged, but even an apparently normal spleen may become movable.
Movable spleen is usually associated with movable left kidney.
Structure. — The spleen is invested by two coats — an external serous and an
internal fibro-elastic coat.
The External or Serous Coat (tunica serosa). — The external or serous coat is
derived from the peritoneum; it is thin, smooth, and in the human subject is inti-
mately adherent to the fibro-elastic coat. It invests the entire organ, except at
the places of its reflection on to the stomach and Diaphragm and at the hilum.
The Fibro-elastic Coat (tunica albuginea). — The fibro-elastic coat forms the
framework of the spleen. It is composed of connective tissue containing muscle-
cells and elastic fibres, and it invests the organ as a capsule, and at the hilum is
reflected inward upon the vessels in the form of sheaths. From these sheaths, as
well as from the inner surface of the fibro-elastic coat, numerous small fibrous
bands, trabeculae (trabeculae lienis) (Figs. 976 and 977), are given off in all direc-
tions; these uniting, constitute the framework of the spleen. This framework
resembles a sponge-like material, consisting of a number of small spaces or
areolae formed by the trabeculae, which are given off from the inner surface of the
capsule, or from the sheaths prolonged inwardly on the blood-vessels. The spaces
or areolae contain the adenoid material known as splenic pulp (pulpa lienis).
The proper coat, the sheaths of the vessels and the trabeculae, consist of a
dense mesh of white and yellow elastic fibrous tissues, the latter decidedly pre-
dominating. It is owing to the presence of this tissue that the spleen possesses
a considerable amount of elasticity, which allows of the very great variations in
size that it presents under certain circumstances. In addition to these con-
stituents of this tunic, there is found in man a small amount of non-striped mus-
cular fibre, and in some mammalia (e. g., dog, pig, and cat) a very considerable
amount, so that the trabeculae appear to consist chiefly of muscular tissue. It is
probably because of this muscular structure that the spleen exhibits, when acted
upon by the galvanic current, faint traces of contractility.
The proper substance of the spleen or splenic-pulp is a soft mass of a dark
reddish-brown color, resembling grumous blood. When a thin section is exam-
ined under a microscope, it is found to consist of a number of branching
cells and an intercellular substance. The cells are connective-tissue corpuscles,
and have been named the sustentacular or supporting cells of the pulp. The
processes of these branching cells communicate with each other, thus forming a
delicate reticulated tissue in the interior of the areolae formed by the trabeculae of
the capsule; so that each primary space may be considered to be divided into a
1364 THE ORGANS OF DIGESTION
number of smaller spaces by the junction of these processes of the branching
corpuscles. These secondary spaces contain blood, in which, however, the white
corpuscles are found to be in larger proportions than in ordinary blood. The
sustentacular cells are either small uni-nucleated or larger multi-nucleated cells;
they do not stain deeply with carmine, like the cells of the Malpighian
bodies, presently to be described (W. Miiller), but like them they possess amce-
boid movements (Cohnheim). In many of them may be seen deep red or
reddish-yellow granules of various sizes which present the characters of the
hsematin of the blood. Sometimes, also, unchanged blood-disks are seen included
in these cells, but more frequently blood-disks are found which are altered both
in form and color. In fact, blood-corpuscles in all stages of disintegration may
be noticed to occur within them. Klein has recently pointed out that sometimes
these cells in the young spleen contain a proliferating nucleus; that is to say,
the nucleus is of large size, and presents a number of knob-like projections,
as if small nuclei were budding from it by a process of gemmation. This obser-
vation is of importance, as it may explain one possible source of the colorless
blood-corpuscles.
The interspaces or areolse formed by the framework of the spleen are thus filled
by a delicate reticulum of branched connective-tissue corpuscles, the interstices of
which are occupied by blood, and in which the blood-vessels terminate in the
manner now to be described.
Blood-vessels of the Spleen. — The splenic artery (Fig. 974) is remarkable for its
large size in proportion to the size of the organs, and also for its tortuous course.
It divides into six or more branches, which enter the hilum of the spleen and
ramify throughout its substance, receiving sheaths from the involution of the
external fibrous tissue. Similar sheaths also invest the nerves and veins.
Each branch runs in the transverse axis of the organ from within outward,
diminishing in size during its transit, and giving off in its passage smaller branches,
some of which pass to the anterior, others to the posterior part. These ultimately
FIG. 977. — Transverse section of the humarr spleen, showing the distribution of the splenic artery and its
branches.
leave the trabecular sheaths, and terminate in the proper substance of the spleen
in small tufts or pencils of minute arterioles, which open into the interstices
of the reticulum formed by the branched sustentacular cells (Figs 977, 978, and
979). Each of the larger branches of the artery supplies chiefly that region of the
organ in which the branch ramifies, having no anastomosis with the majority
of the other branches.
THE SPLEEN
1365
The arterioles (Fig. 979), supported by the minute trabeculae, traverse the pulp
in all directions in bundles or pencilli of straight vessels. Their external coat, on
leaving the trabecular sheaths, consists of ordinary connective tissue, but it grad-
ually undergoes a transformation, becomes much thickened, and is converted into
a lymphoid material.1 This change is effected by the conversion of the con-
nective tissue into a lymphoid tissue, the bundles of connective tissue becoming
looser and laxer, their fibrils more delicate, and containing in their interstices
an abundance of lymph-corpuscles (W. Miiller). This lymphoid material is sup-
plied with blood by minute vessels derived from the artery with which they are
in contact, and which terminates by breaking up into a network of capillary
vessels.
The altered coat of the arterioles, consisting of lymphoid tissue (Fig. 979), pre-
sents here and there thickenings of a spheroidal shape, the Malpighian bodies of the
spleen (noduli lymphatici lienales [Malpighii]} (Fig. 978) These bodies vary in size
from about the y^ of an inch to the -^ of an inch in diameter. They are merely
local expansions or hyperplasiae of the lymphoid tissue of which the external coat of
the smaller arteries of the spleen is formed. They are most frequently found sur-
rounding the arteriole, which thus seems to tunnel them, but occasionally they grow
from one side of the vessel only, and present the appearance of a sessile bud grow-
ing from the arterial wall. Klein, however, denies this, and says it is incorrect to
describe the Malpighian bodies as isolated masses of adenoid tissue, but that they
are always formed around an artery, though there is generally a greater amount on
one side than on the other, and that, therefore, in transverse sections the artery in
the majority of cases is found in an eccentric position. These bodies are visible to
the naked eye on the surface of a fresh section of the organ, appearing as minute
dots of semi-opaque whitish color in the dark
substance of the pulp. In minute structure they
resemble the adenoid tissue of lymphatic glands,
consisting of a delicate reticulum in the meshes
of which lie ordinary lymphoid cells.
The reticulum of the tissue is made up of ex-
tremely delicate fibrils, and is comparatively
open in the centre of the corpuscle, becoming
closer at the periphery of the body. The cells
which it encloses, like the supporting cells of the
pulp, are possessed of amoeboid movements, but
when treated with carmine become deeply
stained, and can thus easily be recognized from
those of the pulp.
The arterioles terminate in capillaries, which
traverse the pulp in all directions; their walls
become much attenuated, lose their tubular
character, and the cells of the lymphoid tissue
of which they are composed become altered ; presenting a branched appearance
and acquiring processes which are directly connected with the processes of the
sustentacular cells of the pulp (Fig. 979). In this manner the capillary vessels
terminate, and the blood flowing through them finds its way into the interstices
of the reticulated tissue formed by the branched connective-tissue corpuscles of
the splenic pulp. Thus the blood passing through the spleen is brought into
intimate relation with the elements of the pulp, and no doubt undergoes important
changes.
After these changes have taken place the blood is collected from the interstices
of the tissue by the rootlets of the veins (Fig. 976), which commence much in the
1 According to Klein, it is the sheath of the small vessel which undergoes this transformation, and forms a
" solid masa of adenoid tissue which surrounds the vessel like a cylindrical sheath." (Atlas of Histology, p. 424.)
FIG. 978. — Part of a Malpighian body
of the spleen of man. a, arterial branch
in longitudinal section ; 6, adenoid tissue,
still containing the lymph-corpuscles ; only
their nuclei are shown ; r, adenoid reticu-
lum, the lymph-corpuscles accidentally re-
moved. (Klein and Noble Smith.)
1366
THE ORGANS OF DIGESTION
same way as the arteries terminate. Where a vein is about to originate the con-
nective-tissue corpuscles of the pulp arrange themselves in rows in such a way as to
form an elongated space or sinus. They become changed in shape, being elongated
and spindle-shaped, and overlap each other at their extremities. They thus form
a sort of endothelial lining of the path or sinus, which is the radicle of a vein.
On the outer surface of these cells are seen delicate transverse lines or markings
which are due to minute elastic fibrillae arranged in a circular manner around the
sinus. Thus the channel obtains a continuous external investment, and grad-
ually becomes converted into a small vein, which after a time presents a coat of
ordinary connective tissue, lined by a layer of fusiform endothelial cells which are
continuous with the supporting cells of the pulp. The smaller veins unite to form
larger ones which do not accompany the arteries, but soon enter the trabecular
sheaths of the capsule, and by their junction form from six or more branches which
emerge from the hilum and, uniting, form the splenic vein, the largest radicle of
the portal vein (Figs. 971 and 975).
The veins are remarkable for their numerous anastomoses, while the arteries
hardly anastomose at all.
The lymphatics originate in two ways — i .e., from the sheaths of the arteries
and in the trabeculae. The former trunks are the deep collecting trunks, and
Supporting cell.
Vessel undergoing lymphoid change.
Small
artery."
Vessel continuous
with processes of
supporting cells.
Supporting cell.
Supporting-
cell
FIG. 979. — Section of spleen, showing the termination of the small blood-vessels.
accompany the blood-vessels; the latter pass to the superficial lymphatic plexust
which may be seen on the surface of the organ. The two sets communicate in
the interior of the organ. The deep trunks at the hilum number from five to
ten, and terminate in the splenic glands. The superficial trunks also pass to the
hilum and terminate in the splenic glands.
The nerves are derived from the splenic plexus, which is part of or connected
with the solar plexus. The nerves enter the spleen with the vessels.
Surface Form. — The spleen is situated under cover of the ribs of the left side, being sepa-
rated from them by the Diaphragm, and above by a small portion of the lower margin of the
left lung and pleura. Its position corresponds to the eighth, ninth, tenth, and eleventh ribs.
It is placed very obliquely. " It is oblique in two directions— viz., from above downward and
outward, and also from above downward and forward" (Cunningham). "Its highest and
lowest points are on a level respectively with the ninth dorsal and first lumbar spines; its inner
end is distant about an inch and a half from the median plane of the body, and its outer end
about reaches the mid-axillary line" (Quain).
Surgical Anatomy. — Injury of the spleen is less common than that of the liver, on account
of its protected situation and connections. It may be ruptured by direct or indirect violence,
torn by a broken rib, or injured by a punctured or gunshot wound. When the organ is enlarged
the chance of rupture is increased. The great risk is hemorrhage, owing to the extreme vascu-
larity of the organ, and the absence of a proper system of capillaries. The injury is not, how-
THE SPLEEN 1367
ever, necessarily fatal, and this would appear to be due in a great measure to the contractile
power of its capsule, which narrows the wound and thus antagonizes the escape of blood. In
cases in which the symptoms suggest such an injury and indicate danger to life, laparotomy must
be performed; and if the hemorrhage cannot be arrested by ordinary surgical methods the spleen
must be removed. The spleen may become displaced, producing great pain from stretching of
the vessels and nerves, and this dislocation may render necessary removal of the organ. The
spleen may become enormously enlarged in certain diseased conditions, such as ague, leukaemia,
syphilis, valvular disease of the heart, or without any obtainable history of previous disease.
It may also become enlarged in lymphadenoma as a part of a general blood disease. In these
cases the mass may fill the abdomen and extend into the pelvis, and may be mistaken for
ovarian or uterine disease.
The spleen is sometimes the seat of cystic tumors, especially hydatids, and of abscess. These
cases require treatment by incision and drainage; and in abscess great care must be taken if
there are no adhesions between the spleen and abdominal cavity, to prevent the escape of any
of the pus into the peritoneal cavity. If possible, the operation should be performed in two
stages. Sarcoma and carcinoma are occasionally found in the spleen, but very rarely as a primary
disease. In movable spleen, if the organ is normal, follow the advice of Rydygier and loosen
the parietal peritoneum to make a pocket, place the spleen in the pocket, and pass sutures through
the parietal peritoneum and the splenic ligaments. A movable diseased spleen should be removed.
Extirpation of the spleen has been performed for wounds or injuries, floating spleen, simple
hypertrophy, and leuksemic enlargement; but in the latter case the operation is now regarded
as unjustifiable, as it is practically certain to terminate fatally. The incision is best made in
the left semilunar line: the spleen is isolated from its surroundings, and the pedicle transfixed
and ligatured in two portions, before the tumor is turned out of the abdominal cavity, if this is
possible, so as to avoid any traction on the pedicle, which may cause tearing of the splenic vein and
which inevitably induces grave shock. In applying the ligatures the surgeon must not include
the tail of the pancreas, and in lifting out the organ care must be taken to avoid rupturing the
capsule.
THE ORGANS OF VOICE AND RESPIRATION.
THE LARYNX.
THE Larynx is the organ of voice, placed at the upper part of the air-passage.
It is situated between the trachea and base of the tongue, at the upper and
forepart of the neck, where it forms a considerable projection in the middle line.
On either side of it lie the great vessels of the neck; behind, it forms part of the
boundary of the pharynx, and is covered by the mucous membrane lining that
cavity. Its vertical extent corresponds to the fourth, fifth, and sixth cervical ver-
tebrae, but it is placed somewhat higher in the female and also during childhood.
In infants between six and twelve months of age Symington found that the tip of
OESOPHAGUS
THYROID
GLAND
8TERNO-THYROID
MUSCLE
STERNUM
THYROID
BRANCH OF
CEPHALIC
ARTERY
FIG. 980. — Sagittal section of a man twenty-one years of age. (After W. Braune.)
the epiglottis was a little above the level of the cartilage between the odontoid
process and body of the axis, and that between infancy and adult life the larynx
descends for a. distance equal to two vertebral bodies and two intervertebral disks.
The movements of the head affect the position of the larynx. When the head is
drawn back, the larynx is lifted, and when the chin approaches the chest the
larynx is depressed. During swallowing the larynx moves distinctly; during sing-
ing it moves slightly. The larynx is suspended by the stylo-hyoid ligament, the
( 1369 )
1370 THE ORGANS OF VOICE AND RESPIRATION
muscles of the upper border of the hyoid bone, the Stylo-pharyngeus and Palato-
pharyngeus muscles. According to Sappey, the average measurements of the adult
larynx are as follows:
In males. In females.
Vertical diameter . . . .44 mm. 36 mm.
Transverse diameter . . . 43 " 41 "
Antero-posterior diameter . . 36 " 26 "
Circumference . . . . 136 " 112 "
Until puberty there is no marked difference between the larynx of the male
and that of the female. In the latter its further increase in size is only slight,
whereas in the former it is great; all the cartilages are enlarged, and the thyroid
becomes prominent as the pomum Adami in the middle line' of the neck, while
the length of the glottis is nearly doubled.
The larynx is broad above, where it presents the form of a triangular box,
flattened behind and at the sides, and bounded in front by a prominent vertical
ridge. Below, it is narrow and cylindrical. It is composed of cartilages, which
are connected together by ligaments and moved by numerous muscles. It is lined
by mucous membrane, which is continuous above with that lining the pharynx and
below with that of the trachea.
In the median line of the neck the larynx has in front of it the skin and cer-
vical fascia. There is often a bursa between the skin and fascia over the most
prominent part of the larynx. It is called -the bursa subcutanea prominentiae
laryngeae. It is present particularly in men, and is seldom found in the
young or in women. The larynx is covered on each side by the thyroid gland,
and the Sterno-hyoid, Sterno-thyroid, Thyro-hyoid, and Omo-hyoid muscles, and
the Inferior constrictors of the pharynx. Posterior is the laryngeal portion of the
pharynx.
The Cartilages of the Larynx (cartilagines laryngis). — The cartilages of the
larynx are nine in number, three single, and three pairs :
Thyroid. Two Arytenoid.
Cricoid. Two Cornicula Laryngis.
Epiglottis. Two Cuneiform.
The Thyroid Cartilage (cartilago thyreoidea) (Figs. 981 and 982). — The thyroid
cartilage (from #v/>£oc, a shield) is hyaline cartilage and is the largest cartilage
of the larynx. It is at the anterior and upper portion of the larynx. It con-
sists of two lateral lamellae or alae, united at an acute angle in front, forming a
vertical projection in the middle line, which is prominent above and called the
pomum Adami (prominentia laryngea). This projection is subcutaneous, is more
distinct in the male than in the female, and is often separated from the integu-
ment by a bursa, the bursa subcutanea prominentiae laryngeae. '
Each lamella is quadrilateral in form. Its outer surface (Fig. 981) presents
an oblique ridge (linea obliqua), which passes downward and forward from a
tubercle situated near the root of the superior cornu, the superior tubercle (tuber-
culwn thyreoideum superius), to a small tubercle near the anterior part of the
lower border, the inferior tubercle (tuberculum thyreoideum inferius). This ridge
gives attachment to the Sterno-thyroid and Thyro-hyoid muscles, and the portion
of cartilage included between it and the posterior border gives attachment to
part of the Inferior constrictor muscle. Just below each superior tubercle there
is often an opening, the thyroid foramen (foramen thyreoideum).
The anterior borders of the alae of the thyroid cartilage which are continuous
below are separated above by a V-shaped notch, the thyroid notch (incisura thy-
reoidea [superior]).
THE LARYNX
1371
The Inner Surface (Fig. 982) of each ala is smooth, slightly concave, and
covered by mucous membrane above and behind; but in front, in the receding
angle formed by their junction, are attached the epiglottis, the true and false
vocal cords, the Thyro-arytenoid and Thyro-epiglottidean muscles, and the
thyro-epiglottidean ligament.
The Upper Border or Margin of the Thyroid Cartilage (Fig. 982) is sinuously curved,
being concave at its posterior part, just in front of the superior cornu, then rising
into a convex outline, which dips in front to form the sides of the thyroid notch,
in the middle line, immediately above the pomum
Adami. This border gives attachment through-
out its whole extent to the thyro-hyoid or hyo-
thyroid membrane.
The Lower Border or Margin (Fig. 982) is nearly
straight in front, but behind, close to the cornu,
it is concave. It is connected to the cricoid cartil-
age, in and near the median line, by the middle
portion of the crico-thyroid membrane (membrana
cricothyreoidea}; and, on either side, by the
Crico-thyroid muscle.
The Posterior Borders (Fig. 982) are thick and
rounded, and each terminates above, in a superior
cornu (cornu superius), and below, in an inferior
cornu (cornu inferius). The two superior cornua
are long and narrow, directed upward, backward,
and inward, and terminate in conical extremities,
which give attachment to the lateral thyro-hyoid
ligaments. The two inferior cornua are short
and thick; they pass downward, with a slight
inclination forward and inward, and each pre-
sents on its inner surface a small oval articular
facet for articulation with the side of the cricoid
cartilage (Fig. 981 ). The posterior border receives
the insertion of the Stylo-pharyngeus and Palato-pharyngeus muscles on each side.
During infancy the alae of the thyroid cartilage are joined to each other by a
narrow, lozenge-shaped strip, named the intrathyroid cartilage. This strip extends
from the upper to the lower border of the thyroid cartilage in the middle line,
and is distinguished from the alae by being more transparent and more flexible.
The Cricoid Cartilage (cartilago cricoidea) (Figs. 981, 982, and 984). — The cri-
coid cartilage is so called from its resemblance to a signet ring (xpixot;, a ring}.
It is smaller, but thicker and stronger than the thyroid cartilage, and forms the
lower and*back part of the cavity of the larynx. It is hyaline cartilage and con-
sists of two parts: a quadrate portion, situated behind, and a narrow ring or
arch, one-fourth or one-fifth the depth of the posterior part, situated in front.
The posterior square portion rapidly narrows at the sides of the cartilage, at the
expense of the upper border, into the anterior portion.
Its Posterior Portion or Lamina (lamina cartilaginis cricoideae) is very deep and
broad, and measures from above downward about an inch (2 to 3 cm.) ; it presents,
on its posterior surface, in the middle line, a vertical ridge for the attachment of
the longitudinal fibres of the oesophagus; and on either side a broad depression
for the Crico-arytenoideus posticus muscle.
Its Anterior Portion or Arcus (arcu* cartilaginis cricoideae) is narrow and convex,
and measures vertically about one-fourth or one-fifth of an inch (5 to 7 cm.) ;
it affords attachment externally in front and at the sides to the Crico-thyroid
muscles, and, behind, to part of the Inferior constrictor..
FIG. 981. — Side view of the thyroid
and cricoid cartilages.
1372
THE ORGANS OF VOICE AND RESPIRATION
Epiglottis.
At the point of junction of the posterior quadrate portion with the rest of the
cartilage is a small round elevation, for articulation with the inferior cornu of the
thyroid cartilage.
The Lower Border of the cricoid cartilage is horizontal, and connected to the
upper ring of the trachea by fibrous membrane (Figs. 981 and 983).
Its Upper Border is directed obliquely upward and backward, owing to the
great depth of the posterior surface. It gives attachment, in front, to the middle
portion of the crico-thyroid mem-
brane ; at the sides, to the lateral
portion of the same membrane
and to the lateral Crico-arytenoid
muscle; behind, it presents, in the
middle, a shallow notch, and on
each side of this is a smooth, oval
surface, directed upward and out-
ward, for articulation with the
arytenoid cartilage.
The Inner Surface of the cricoid
cartilage is smooth, and lined with
mucous membrane.
The Arytenoid Cartilages (cartil-
agines arytaenoideae) (Figs. 982,
985, and 989). — The arytenoid
cartilages are so called from the
resemblance they bear, when ap-
proximated, to the mouth of a
pitcher (apuratva, a pitcher). They
are two in number, and situated
at the upper border of the cricoid
cartilage, at the back of the larynx
in the interval between the poste-
rior borders of the alae of the thy-
roid cartilages. Each cartilage is
in form a three-sided pyramid, and
presents for examination three sur-
faces, a base, and an apex.
The Posterior Surface is trian-
gular, smooth, concave, and gives
attachment to the transverse por-
Thyroid.
Cornicula laryngis.
Cuneiform cartilage. ^^^ ^ \
O
Arytenoid.
Insertion of
CRICO-ARYTENOIOEUS
POSTICUS ET LATERALIS
Posterior
surface.
Arytenoid cartilages, base.
Cricoid.
Articular facet for
arytenoid cartilage.
Articular facet for
inferior cornu of
thyroid cartilage.
FIG. 982. — The cartilages of the larynx. Posterior view.
tion of the Arytenoid muscle.
The Anterior or External Surface
is somewhat convex and rough. It
presents, near its apex, a small
elevation, the colliculus; from this a
ridge (crista arcuatd) passes back-
ward and then forward and down-
ward into a sharp-pointed process, the vocal process. This ridge separates a
deep depression above, the fovea triangularis, from a broader and shallower depres-
sion below, the fovea oblonga. A short distance above the base a small tubercle
gives origin to the ligament of the false vocal cord, the superior thyro-arytenoid
ligament. To the outer part of the ridge, as well as the surface above and below,
is attached the Thyro-arytenoid muscle.
The Internal Surface is narrow, smooth, and flattened, covered by mucous
membrane, and forms the lateral boundary of the respiratory part of the glottis.
THE LARYNX 1373
The Base (basis) of each cartilage is broad, and presents a concave smooth sur-
face, for articulation with the cricoid cartilage. Two of its angles require special
mention: the external angle, which is short, rounded, and prominent, projects
backward and outward, and is termed the muscular process (processus muscularis),
from receiving the insertion of the Posterior and Lateral crico-arytenoid muscles.
The anterior angle, also prominent, but more pointed, projects horizontally forward,
and gives attachment to the inferior thyro-arytenoid ligament, the supporting liga-
ment of the true vocal cord. This angle is called the vocal process (processus vocalis).
The Apex of each cartilage is pointed, curved backward and inward, and sur-
mounted by a small conical, cartilaginous-nodule, the corniculum laryngis, articu-
lated with or united to the arytenoid cartilage.
The Cornicula Laryngis or Caitilages of Santorini (cartilagines cornicuLatae) (Figs.
982 and 988). — The cornicula laryngis are two small conical nodules, consisting
of white fibre-cartilage, which articulate with the summit of the arytenoid carti-
lages and serve to prolong them backward and inward. To them are attached
the aryteno-epiglottidean folds. They are sometimes united to the arytenoid
cartilages.
The Cuneiform Cartilages or Cartilages of Wrisberg (cartilagines cuneijorm.es]
(Figs. 982 and 984). — The cuneiform cartilages are two small, elongated, carti-
laginous bodies, placed one on each side, in the fold of mucous membrane which
extends from the apex of the arytenoid cartilage to the side of the epiglottis, and
is called the aryteno-epiglottidean fold (plica aryepiglottica) (Fig. 984); they give
rise to small whitish elevations on the inner surface of the mucous membrane,
just in front of the arytenoid cartilages.
The Epiglottis or the Cartilage of the Epiglottis (cartilago cpiglcltica] (Figs. 980, 982,
983, 984, 985, and 988). — The epiglottis is a thin, flexible lamella of fibro-cartilage,
of a yellowish color, shaped like a leaf, and placed behind the tongue in front of
the superior opening of the larynx. Its free extremity, which is directed upward,
is broad and rounded, and often notched; its attached part (petiolus epiglottidis)
is long, narrow, and connected to the receding angle between the alae of the
thyroid cartilage, just below the median notch, by a long, narrow ligamentous
band, the thyro-epiglottic ligament (Fig. 985). It is also connected to the posterior
surface of the body of the hyoid bone by an elastic ligamentous band, the hyo-
epiglottic ligament.
Its Anterior or Lingual Surface is curved forward, toward the tongue, and cov-
ered at its upper, free part by mucous membrane, which is reflected on to the
sides and base of the organ, forming a median and two lateral folds, the glcsso-
epiglottidean folds (Fig. 984). The median glosso-epiglottidean fold contains the
elastic glosso-epiglottic ligament (ligamentum glossocpiglotticum) . Each lateral
glosso-epiglottidean fold runs from the front and side of the base of the epiglottis
to the side of the tongue. The depression between the epiglottis and the base of the
tongue on each side of the median fold is named the vallecula epiglottica. The
lower part of the anterior surface of the epiglottis lies behind the hyoid bone,
the thyro-hyoid membrane, and upper part of the thyroid cartilage, but is separated
from these structures by a mass of fatty tissue.
Its Posterior or Laryngeal Surface is smooth, concave from side to side, concavo-
convex from above downward; its lower part projects backward as an elevation,
the tubercle or cushion (tuberculum epiglotticum)(Fig. 983) ; when the mucous mem-
brane is removed, the surface of the cartilage is seen to be studded with a number
of small mucous glands, which are lodged in little pits upon its surface. To its
sides the aryteno-epiglottidean folds are attached (Fig. 984).
Structure. — The cuneiform cartilages, the epiglottis, and the apices of the
arytenoids are composed of yellow elastic cartilage, which shows little tendency to
calcification; on the other hand, the thyroid, cricoid, and the greater part of the
1374 THE ORGANS OF VOICE AND RESPIRATION
arytenoids consist of hyaline cartilage, and become more or less ossified as age
advances. Ossification commences about the twenty-fifth year in the thyroid car-
tilage, somewhat later in the cricoid and arytenoids; by the sixty-fifth year these
cartilages may be completely converted into bone. The cornicula laryngis consist
of white fibre-cartilage, which becomes osseous about the seventieth year.
Ligaments, Joints, and Membranes of the Larynx. — The ligaments of the larynx
are extrinsic — i. e., those connecting the thyroid cartilage and epiglottis with the
hyoid bone, and the cricoid cartilage with the trachea; and intrinsic, those which
connect the several cartilages of the larynx to each other.
The ligaments connecting the thyroid cartilage with the hyoid bone are three
in number — the thyro-hyoid membrane, and the two lateral thyro-hyoid ligaments.
The Thyro-hyoid or Hyo-thyroid Membrane or Ligament (membrana hyothyreoidea)
(Fig. 985) is a broad, fibre-elastic, membranous layer, attached below to the
upper border of the thyroid cartilage, and above to the posterior border of the
body and greater cornua of the hyoid bone, passing behind the postero-inferior
surface of the hyoid, and being separated from this surface by a synovial bursa
(bursa m. sternohyoidei) , which facilitates the upward movement of the larynx
during deglutition. The membrane is thicker in the middle line than at either
side. This thickening is due to elastic fibres, and constitutes the middle thyro-
hyoid ligament (ligamentum hyothyreoideum medium). On each side the posterior
extremity of the membrane is thickened by elastic fibres, constituting the lateral
thyro-hyoid ligament (ligamentum hyothyreoideum later ale). The thyro-hyoid
membrane is pierced on each side by the superior laryngeal .vessels and the
internal laryngeal nerve. The anterior surface of the thyro-hyoid membrane is
in relation with the Thyro-hyoid, Sterno-hyoid, and Omo-hyoid muscles and with
the body of the hyoid bone. The two lateral ligaments are rounded, elastic cords,
which pass between the superior cornua of the thyroid cartilage and the extremi-
ties of the greater cornua of the hyoid bone. A small cartilaginous nodule (car-
tilago triticea), sometimes bony, is frequently found in each.
The Membrana Quadrangularis is an elastic membrane containing numerous
glands. The fibres of the membrane run in part downward and in part down-
ward and backward. The membrane on each side arises in front and above at
the lateral margin of the cartilage of the epiglottis, below at the posterior surface
of the angle of the thyroid cartilage and becomes attached behind to the cornicula
laryngis and to the inner margins of the arytenoid cartilages.1 The membranes
converge below and medianward. The ligamentum ventriculare is the superior
end of the membrane (Spalteholz) . The fibres constituting the ligamentum ven-
triculare are given off at the thyroid cartilage above the ligamentum vocale and
pass horizontally backward to the medial margin of the fovea triangularis of the
arytenoid cartilage.2 The epiglottis is connected to the tongue by the three
glosso-epiglottidean folds of mucous membrane, which may also be considered
as extrinsic ligaments of the epiglottis.
The Glosso-epiglottidean Folds or Ligaments (plicae epiglotticae) (Fig. 984) num-
ber three. The middle glosso-epiglottidean fold (plica glossoepiglottica mediana)
passes from the middle of the anterior free surface of the epiglottis to the base
of the tongue. It contains the glosso-epiglottic ligament. The lateral glosso-
epiglottidean or the pharyngo-epiglottidean fold (plica glossoepiglottica lateralis)
on each side passes from the side of the epiglottis to the side of the base of the
tongue and to the pharyngeal wall. On each side between the median and lateral
folds is a depression, the vallecula epiglottica.
The Hyo-epiglottic Ligament ((ligamentum hyoepiglotticum) is an elastic band,
which extends from the anterior surface of the epiglottis, near its apex, to the
1 Hand Atlas of Human Anatomy. By Werner Spalteholz. Translated and edited by Lewellys F. Barker.
2 Ibid.
THE LARYNX
1375
upper border of the body of the hyoid bone. The epiglottis is attached to the
thyroid cartilage, below and behind the superior thyroid notch, by the strong
and elastic thyro-epiglottic ligament (iigamentum thyreoepiglotticum) (Fig. 985).
Between the epiglottis, the hyo-epiglottic ligament, and the thyro-hyoid membrane
is a triangular space containing fat on each side of the median line.
The ligaments connecting the thyroid cartilage to the cricoid are also three in
number — the crico-thyroid membrane and the capsular ligaments.
The Crico-thyroid Membrane (conus elasticus) (Figs. 971 and 988 is an elastic mem-
brane which passes radially from the posterior surface of the angle of the thyroid
cartilage to the upper margin of the arch of the cricoid cartilage and to the vocal
processes of the arytenoid cartilages. It is composed mainly of yellow elastic
tissue. It consists of three parts, a central triangular portion and two lateral
portions. The central part (Iigamentum cricothyreoideum medium) is thick and
strong, narrow above and broadening out below. It connects together the con-
tiguous margins of the thyroid and cricoid cartilages. It is convex, concealed on
each side by the Crico-thyroid muscle, but subcutaneous in the middle line; it is
crossed horizontally by a small anastomotic arterial arch, formed by the junction
of the two crico-thyroid arteries. The lateral portions are thinner and lie close
under the mucous membrane of the larynx. They extend from the superior
border of the cricoid cartilage to the inferior margin of the true vocal cords with
which they are continuous. On each side are the uppermost fibres from the
inferior thyro-arytenoid ligament (Iigamentum vocale).
The lateral portions are lined internally by mucous membrane, and are sepa-
rated from the thyroid cartilage by the lateral Crico-arytenoid and Thyro-aryte-
noid muscles. This membrane
and the muscles just men-
tioned reduce greatly the inte-
rior of the larynx. The crico-
thyroid membrane with the
membrana quadrangularis con-
stitute the membrana elastica
laryngis.
The Crico-thyroid Articulation
(articulatio cricothyreoidea) (Fig.
981), on each side of the inferior
cornu of the thyroid, with the
cricoid cartilage on each side.
A loose synovial membrane (cap-
sula articularis cricothyreoidea)
encloses the articulation.
The synovial capsule is
strengthened by the ligamenta
ceratocricoidea,which pass from
the lesser cornu of the thyroid
to the lamina of the cricoid
cartilage.
The Crico-arytenoid Articula-
tion (articulatio cricoarytae-
noidea) (Fig. 982) on each side is between the articular surface of the arytenoid
cartilage and the arytenoid articular surface of the cricoid cartilage.
The ligaments connecting the arytenoid cartilages to the cricoid are on each
side a capsular ligament (capsula articularis cricoarytaenoidea) and a posterior
crico-arytenoid ligament (Iigamentum cricoarytaenoideum posterius). The capsular
ligaments are thin and loose capsules attached to the margin of the articular
ARYTENO-
CPIGLOTTIDEUS
CRICO-
THYREOIDCUS
LARYNGEAL
SACCULE
, ,_ INFERIOR
VOCAL CORD
FIG. 983. — Coronal section of larynx, rear view of front half.
(Testut.)
1376 THE ORGANS OF VOICE AND RESPIRATION
surfaces; they are lined internally by synovial membrane. The posterior crico-
arytenoid ligaments extend from the cricoid to the inner and back part of the base
of the arytenoid cartilage.
The Crico-tracheal Ligament (ligamentum cricotracheale) connects the cricoid
cartilage with the first ring of the trachea. It resembles the fibrous membrane
which connects the cartilaginous rings of the trachea to each side.
There is on each side an articulation between the arytenoid cartilage and the
cartilage of Santorini (synchondrosis arycorniculala). The cartilage of Santo rini is
somewhat movable and is fixed to the arytenoid by lax connective tissue. From
each cartilage of Santorini a band of connective tissue runs doAvn to the lamina
of the cricoid cartilage and to the pharyngeal mucous membrane. Beneath the
arytenoid muscles the ligaments from the two sides join and pass down together.
Thus is formed a Y-shaped ligament called the ligamentum corniculopharyngeum.
The portion between the cricoid cartilage and the mucous membrane of the
pharynx is sometimes called the ligamentum cricopharyngeum.
Interior of the Larynx (Figs. 983, 984, and 985).— The cavity of the larynx
(cavum laryngis) extends fro n the superior aperture of the larynx to the lower
border of the cricoid cartilage. It is divided into two parts by the projection
inward of the true vocal cords, between which is a narrow triangular fissure or
chink, the rima glottidis. It is further subdivided by the false vocal cords. So
we consider the larynx as divided into a portion above the false cords, a porT
tion between the false and true vocal cords, and a portion below the true cords.
The entrance of the first compartment is the superior aperture of the larynx.
The Superior Aperture of the Larynx (aditus laryngis}. — The superior aperture
of the larynx (Figs. 983 and 984) is a triangular or cordiform opening, wide in front,
narrow behind, and sloping obliquely downward and backward. It is bounded,
in front, by the epiglottis; behind, by the apices of the arytenoid cartilages and
the cornicula laryngis; and laterally, by a fold of mucous membrane, enclosing
ligamentous and muscular fibres, stretched between the sides of the epiglottis
and the apices of the arytenoid cartilages; these are the aryteno-epiglottidean
folds (Figs. 984 and 985), on the margins of which the cuneiform cartilages form
more or less distinct whitish prominences.
The small gap between the cartilages of Santorini is called the incisura inter-
arytaenoidea. On the pharynx, on either side of the posterior portion of the superior
aperture of the larynx, is a recess, called the sinus pyriformis.
Upper Compartment or Vestibule of the Laryngeal Cavity (vestibulum laryngis) (Figs.
983 and 985). — The vestibule is the portion between the superior opening and the
false vocal cords. It is much narrower below than above. It is bounded anteriorly
by the mucous membrane-covered epiglottis. The lower part of the epiglottis
exhibits a prominence called the cushion or tubercle (Fig. 983). The lateral wall of
the vestibule on each side is the aryteno-epiglottidean fold (Fig. 985), which extends
from the summit of the arytenoid cartilage forward, upward, and outward to the
margin of the epiglottis, and which contains fibres of the Thyro-epiglottideus and
Arytenoideus muscles (musculus arytaenoepiglottidean). Near the posterior end
of the fold are two trivial elevations: the anterior elevation is caused by the promi-
nence of the cuneiform cartilage, and is called the cuneiform tubercle of Wrisberg
(tuberculum cuneiforme [Wrisbergi]) ; the posterior elevation is caused by the
anterior margin of the arytenoid cartilage and the cartilage of Santorini, and is
called the comical tubercle of Santorini (tuberculum corniculatum [Santorini]).
Between these elevations is a groove, the filtrum ventriculi of Merkel, which passes
into the space between the false and true vocal cords. The anterior elevation
passes into the false vocal cord, the posterior elevation into the true vocal cord.
The posterior portion of the laryngeal vestibule is the narrow space between
the upper portions of the arytenoid cartilages.
THE LARYNX
1377
The Middle Compartment of the Larynx (Figs. 983 and 985). — This lies between the
false vocal cords above and the true vocal cords below. It is the smallestof the laryn-
geal compartments. It opens into the vestibule by way of the gap between the
false vocal cords, which is called the false glottis; it opens into the lower compart-
ment of the larynx by way of the space between the true vocal cords, the true glottis.
The True Glottis. — The true glottis is the apparatus for producing tone and is
formed by the true vocal cords.
The Chink of the Glottis (rima glottidis) (Figs. 983 and 984).— The chink of the
glottis is the elongated fissure or chink between the inferior or true vocal cords in
front, and between the bases and vocal processes of the arytenoid cartilages behind.
It is therefore frequently subdivided into an anterior, interligamentous or vocal por-
tion, the glottis vocalis (pars intermembranacea) , and a posterior, intercartilaginous
or respiratory portion, the glottis respiratoria (pars intercartilaginea). Posteriorly it is
limited by the mucous membrane passing between the arytenoid cartilages. The
vocal portion averages about three-fifths of the length of the entire aperture. It
is the narrowest part of the cavity of the larynx, and its level corresponds to the
APEX OF SUP. HORN OF
THYROID CARTILAGE
INFERIOR
VOCAL CORD,
CORNICULUM
LARYNGIS
CUNEIFORM
CARTILAGE
ARYTENO-EPIGLOT-
TIDIAN FOLD
APEX OF GREAT
HORN OF HYOID
LATERAL GLOSSO- MIDDLE GLOSSO-
EPIGLOTTIDIAN FOLD EPIG LOTTI Ol AN FOLD
FIG. 984. — Larynx, viewed from above.
(Testut.)
bases of the arytenoid cartilages. Its length, in the male, measures rather less
than an inch (20 to 25 mm.); in the female it is shorter by 5 or 6 mm., or three
lines. The width and shape of the rima glottidis vary with the movements of the
vocal cords and arytenoid cartilages during respiration and phonation. In the
condition of rest — i. e., when these structures are uninfluenced by muscular action,
as in quiet respiration, the glottis vocalis is triangular, with its apex in front and
its base behind, the latter being represented by a line about 8 mm. long, connect-
ing the anterior extremities of the vocal processes, while the inner surfaces of the
arytenoids are parallel to each other, and hence the glottis respiratoria is rectan-
gular. During extreme adduction of the cords, as in the emission of a high note,
the glottis vocalis is reduced to a linear slit by the apposition of the cords, while
the glottis respiratoria is triangular, its apex corresponding to the anterior extrem-
ities of the vocal processes of the arytenoids, which are approximated by the
inward rotation of the cartilages. Conversely in extreme abduction of the cords,
as in forced inspiration, the arytenoids and their vocal processes are rotated out-
ward, and the glottis respiratoria is triangular in shape, but with its apex directed
backward. In this condition the entire glottis is somewhat lozenge-shaped, the
sides of the glottis vocalis diverging from before backward, those of the glottis
87
1378
THE ORGANS OF VOICE AND RESPIRATION
respiratoria diverging from behind forward, the widest part of the aperture corre-
sponding with the attachment of the cords to the vocal processes.1
The Superior or False Vocal Cords (plicae ventricular es] (Figs. 983, 984, and 985), so
called because they are not directly concerned in the production of the voice. Each
is a thick fold of mucous membrane, enclosing a narrow band of fibrous tissue, the
superior thyro-arytenoid ligament, which is attached in front to the angle of the
thyroid cartilage immediately below the attachment of the epiglottis, and behind
to the anterior surface of the arytenoid cartilage. The lower border of this liga-
ment, enclosed in mucous membrane, forms a free crescentic margin, which con-
stitutes the upper boundary of the ventricle of the larynx. The false vocal cord
contains the lower part of the membrana quadrangularis with the ligamentum
ventriculare, the muscle ventricularis, and laryngeal glands.
The Inferior or True Vocal Cords (plicae vocales)(F'}gs. 983, 984, 985, and 989), so
called from their being concerned in the production of sound. Each is a strong
HYOID
VHYRO-HYOIDEUS
THYRO-EPIGLOT
TIC LIGAMENT
ARYTENO-EPI-
GLOTTIDIAN FOLD
CRICOID
CARTILAGE
FIG. 985. — Sagittal section of larynx, right half. (Testut.)
band, the inferior thyro-arytenoid ligament (ligamentum vocale) , covered on its sur-
face by a thin layer of mucous membrane. Each ligament consists of a band of
yellow elastic tissue, attached in front to the depression between the alae of the
thyroid cartilage, and behind to the anterior angle of the base of the arytenoid.
This angle is called the vocal process. Its lower border is continuous with the
thin lateral part of the crico-thyroid membrane. Its upper border forms the lower
boundary of the ventricle of the larynx. Externally, the Thyro-arytenoideus
muscle lies parallel with it. It is covered internally by mucous membrane, which is
extremely pale, thin, and closely adherent to its surface. The upper margin of
the true vocal cord is covered with mucous membrane, and is the lower boundary
of the ventricle of the larynx. Over the vocal process it is yellowish (macula
flava). The true vocal cord contains the upper part of the crico-thyroid mem-
brane with the ligamentum vocale and the muscle vocalis.
1 On the shape of the rima glottidis, in the various conditions of breathing and speaking, see Czermak. On the
Laryngoscope, translated for the New Sydenham Society. — ED. of 15th English edition.
THE LARYNX '
1379
The Ventricle of the Larynx or Laryngeal Sinus (ventriculus laryngis [Morgagnii])
(Figs. 970 and 972) is an oblong fossa, situated between the superior and inferior
vocal cords on each side, and extending nearly their entire length. This fossa is
bounded, above, by the free crescentic edge of the superior vocal cord; below, by
the straight margin of the inferior vocal cord; externally, by the mucous mem-
brane covering the corresponding Thyro-arytenoideus muscle. The anterior part
of the ventricle leads up by a narrow opening into a caecal pouch of mucous
membrane of variable size, called the laryngeal pouch.
The Laryngeal Saccule or Pouch (appendix ventriculi) (Fig. 983), or laryngeal
pouch, is a membranous sac, placed between the superior vocal cord and the inner
surface of the thyroid cartilage, occasionally extending as far as its upper border
or even higher; it is conical in form, and curved slightly backward. On the surface
of its mucous membrane are the openings of sixty or seventy mucous glands, which
are lodged in the submucous areolar tissue. This sac is enclosed in a fibrous cap-
sule, continuous below with the superior thyro-arytenoid ligament; its laryngeal
surface is covered by the Aryteno-epiglotticleus inferior muscle (compressor sacculi
laryngis of Hilton); while its exterior is covered by the Thyro-arytenoideus and
Thyro-epiglottideus muscles. These muscles compress the sacculus laryngis, and
discharge the secretion it contains upon the Vocal cords, the surfaces of which it is
intended to lubricate.
STERNO-
'THYREOIDEUS
FIG. 986. —Muscles of larynx, front view. The sterno-
thyroids and right thyro-hyoid have been removed.
(Testut.)
FIG. 987. — Muscles of larynx, from behind.
(Testut.)
The Lower Compartment of the Larynx (Figs. 983 and 985). — This space is just
beneath the true vocal cords and leads into the trachea. It is called the additus glot-
tidis inferior. Above, on cross-section, it is oval; below, it is round. It is bounded
by the inner surface of the crico-thyroid membrane and the cricoid cartilage.
Muscles of the Larynx (miLSculi laryngis}. — We do not consider all muscles
which are attached to laryngeal cartilages as laryngeal muscles. Some muscles
so attached in reality belong to other regions, for instance, the Inferior constric-
tor, the Stylo-pharyngeus, the Sterno-thyroid, the Thyro-hyoid, and the Palato-
pharyngeus. The muscles which really belong to the larynx are called intrinsic.
Four muscles of the vocal cords and rima glottidis are paired and one is single.
1380
THE ORGANS OF VOICE AND RESPIRATION
The paired musclas are the crico-thyroid, the posterior crico-arvtenoid, the
lateral crico-arytenoid, and the thyro-arytenoid. The single muscle is the aryte-
noideus.
A Crico-thyroid (m. cricothyreoideus] (Figs. 981, 983, and 986) is placed on each
side. It is triangular in form, and situated at the forepart and side of the cricoid
cartilage. It arises from the front and lateral part of the cricoid cartilage; its
fibres diverge, passing obliquely upward and outward to be inserted into the lower
border of the thyroid cartilage and into the anterior border of the lower cornu.
The inner borders of these two muscles are separated in the middle line by a
triangular interval occupied by the central part of the crico-thyroid membrane.
The Posterior Crico-arytenoid (m. cricoarytaenoideus posterior) (Figs. 987, 988, and
989), a paired muscle, arises from the
broad depression occupying each lat-
eral half of the posterior surface of the
cricoid cartilage; its fibres pass up-
ward and outward, converging to be
inserted into the outer angle (muscu-
Cornicula
laryngis
Articular facet for
inferior cornu of
thyroid cartilage.
FIG. 988. — Muscles of larynx. Side view. Eight ala
of thyroid cartilage removed.
FIG. 989. — Interior of the larynx, seen from above.
(Enlarged.)
lar process) of the base of the arytenoid cartilage. The upper fibres are nearly
horizontal, the middle oblique, and the lower almost vertical.1
The Arytenoideus (Figs. 985, 987, 988, and 989) is a single muscle filling up the
posterior concave surface of the arytenoid cartilages. It arises from the posterior
surface and outer border of one arytenoid cartilage, and is inserted into the corre-.
sponding parts of the opposite cartilage. It consists of three planes of fibres, two
oblique and one transverse. The oblique fibres (m. arytaenoideus obliquus), the
most superficial, form two fasciculi, which pass from the base of one cartilage to
the apex of the opposite one. The transverse fibres (m. arytaenoideus transversus),
the deepest and most numerous, pass transversely across between the two cartil-
ages; hence the Arytenoideus was formerly considered as three muscles, the trans-
1 Merkel, of Leipzig, has described a muscular slip which occasionally extends between the outer border of the
sterior surface of the cricoid cartilage and the posterior margin of the inferior cornu of the thyroid ; this he
po
calls the " Musculus kerato-cricoideus." It is not found in every larynx, and when present exists usually only
on one side, but is occasionally found on both sides. Sir William Turner (Edinburgh Medical Journal, February,
1860) states that it is found in about one case in five. Its action is to fix the lower horn of the thyroid cartilage
backward and downward, opposing in some measure the part of the Crico-thyroid muscle, which is connected to
the anterior margin of the horn. — ED. of 15th English edition.
THE LARYNX 1381
verse and the two oblique. A few of the oblique fibres are around the outer margin
of the cartilage, and blend with the Thyro-arytenoid in the aryteno-epiglottidean
fold, and are called the Aryteno-epiglottideus muscles.
In order to expose the rest of the muscles of the larynx the thyroid cartilage
of one side must be removed. Begin by taking away the crico-thyroid muscle,
then dividing the lateral thyro-hyoid ligament; disarticulate the inferior cornu of
the thyroid cartilage from the cricoid cartilage, then carefully cut through the
thyroid cartilage a short distance from its union with its twin. The following
muscles will then be exposed after a little cleaning: the Lateral crico-thyroid,
the Thyro-arytenoid, the Thyro-epiglottideus.
The Lateral Crico-arytenoid (m. cricoarytenoidetis lateralis] (Figs. 988 and 989),
a paired muscle, is smaller than the preceding, and of an oblong form. It arises
from the upper border of the side of the cricoid cartilage, and, passing obliquely
upward and backward, is inserted into the muscular process of the arytenoid
cartilage in front of the posterior Crico-arytenoid muscle.
The Thyro-arytenoid (m. thyroarytaenoideus) (Figs. 988 and 989), a paired muscle,
is broad and flat. It lies parallel with the outer side of the true vocal cord. It
arises in front from the lower half of the receding angle of the thyroid cartilage,
and from the crico-thyroid membrane. Its fibres pass backward and outward, to
be inserted into the base and anterior surface of the arytenoid cartilage. This
muscle consists of two fasciculi.1 The inner or inferior fasciculus (m. vocalis), the
thicker, is prismatic in shape and is inserted into the vocal process of the aryte-
noid cartilage, and into the adjacent portion of its anterior surface; it lies parallel
with the true vocal cord, to which it is adherent. This fasciculus on its deeper
surface gives off some fibres which are attached to the true vocal cord. These
are called the ary-vocalis (Ludwig). The outer or superior fasciculus, the thinner,
is inserted into the anterior surface and outer border of the arytenoid cartilage
above the preceding fibres; it lies on the outer side of the sacculus laryngis, imme-
diately beneath the mucous membrane.2
The muscles of the epiglottis are the —
Thyro-epiglottideus. Aryteno-epiglottideus superior.
Aryteno-epiglottideus inferior.
The Thyro-epiglottideus (m. thyroepiglotticus) is a delicate fasciculus, which
arises from the inner surface of the thyroid cartilage, just external to the origin of
the Thyro-arytenoid muscle, of which it is sometimes described as a part, and
spreads over the outer surface of the sacculus laryngis ; some of its fibres are lost
in the aryteno-epiglottidean fold, while the others are continued forward to the
margin of the epiglottis.
The Aryteno-epiglottideus (Figs. 983 and 988) is properly divided into two
muscles, a superior and an inferior.
The Aryteno-epiglottideus superior consists of a few delicate muscular fasciculi,
which arise from the apex of the arytenoid cartilages, and become lost in the
fold of mucous membrane, the aryteno-epiglottidean fold, extending between the
arytenoid cartilage and the side of the epiglottis.
The Aryteno-epiglottideus inferior, the Compressor sacculi laryngis of Hilton, arises
from the arytenoid cartilage, just above the attachment of the superior vocal cord;
passing forward and upward, it spreads out upon the anterior surface of the epiglot-
tis. This muscle is separated from the preceding by an indistinct areolar interval.3
1 Henle describes these two portions as separate muscles, under the names of the External and Internal thyro-
arytenoid. — ED. of 15th English edition.
2 Luschka has described a small but fairly constant muscle as the Arytenoideus rectus. It is attached below
to the posterior concave surface of the arytenoid cartilage, beneath the Arytenoideus muscle, and, passing
upward, emerges at the upper border of this muscle, and is inserted into the posterior surface of the cartilage of
Santorini (Anatomy, by Hyrtl, p. 718). — ED. of 15th English edition.
3 MusruLus TRiTicEO-GLOSSOS. Bochdalek, Jr. (Prager Vierteljahrsschrift, 1866, 2d part) describes a muscle
hitherto entirely overlooked, except by Henle, who makes a brief statement in his Anatomy, which arises from
the nodule of cartilage (corpus triticewn) in the posterior thyro-hyoid ligament, and passes forward and upward
to enter the tongue along with. the Hyo-glossus muscle. He met with this muscle eight times in twenty-two sub-
jects. It occurred in both sexes, sometimes on both sides, at others on one only. — ED. of 15th English edition.
1382 THE ORGANS OF VOICE AND RESPIRATION
Actions. — In considering the action of the muscles of the larynx, they may
be conveniently divided into two groups, viz.: 1. Those which open and close
the glottis. 2. Those which regulate the degree of tension of the vocal cords.
1. The muscles which open the glottis are the two Posterior crico-arytenoids;
and those which close it are the Arytenoideus and the two Lateral crico-arytenoids.
2. The muscles which regulate the tension of the vocal cords are the two Crico-
thyroids, which tense and elongate them, and the two Thyro-arytenoids, which
relax and shorten them. The Thyro-epiglottideus is a depressor of the epiglottis,
and the Aryteno-epiglottideus, superior and inferior, constrict the superior aper-
ture of the larynx.
The Posterior crico-arytenoids separate the chordae vocales, and consequently open the glottis,
by rotating the arytenoid cartilages outward around a vertical axis passing through the crico-
arytenoid joints, so that their vocal processes and the vocal cords attached to them become widely
separated.
The Lateral crico-arytenoids close the glottis by rotating the arytenoid cartilages inward so
as to approximate their vocal processes.
The Arytenoideus muscle approximates the arytenoid cartilages, and thus closes the opening
of the glottis, especially at its back part.
The Crico-thyroid muscles produce tension and elongation of the vocal cords. This is effected
as follows: the thyroid cartilage is fixed by its extrinsic muscles; then the Crico-thyroid muscles,
when they act, draw upward the front of the cricoid cartilage, and so depress the posterior por-
tion, which carries with it the arytenoid cartilages, and thus elongate the vocal cords.
The Thyro-arytenoid muscles, consisting of two parts having different attachments and
different directions, are rather complicated as regards their action. Their main use is to draw
the arytenoid cartilages forward toward the thyroid, and thus shorten and relax the vocal cords.
But, owing to the connection of the inner portion with the vocal cord, this part, if acting sepa-
rately, is supposed to modify its elasticity and tension, and the outer portion, being inserted
into the outer part of the anterior surface of the arytenoid cartilage, may rotate it inward, and
thus narrow the rima glottidis by bringing the two cords together.
The T ' hyro-epiglottidei may depress the epiglottis; they assist in compressing the sacculi
laryngis. The Aryteno-epiglottideus superior constricts the superior aperture of the larynx,
when it is drawn upward, during deglutition. The aryteno-epiglottideus inferior, together with
some fibres of the Thyro-arytenoidei, compress the sacculus laryngis.
The Mucous Membrane of the Larynx is continuous above with that lining the
mouth and pharynx, and it is prolonged through the trachea and bronchi into the
lungs. It lines the posterior surface and the anterior part of the upper surface of
the epiglottis, to which it is closely adherent. In the rest of the larynx, above the
true vocal cords, it is lax and rests upon a considerable submucous layer. The
mucous membrane, with the submucous coat, ligamentous and muscular fibresr
forms the aryteno-epiglottidean folds, which folds are the lateral boundaries of the
superior aperture of the larynx. It lines the whole of the cavity of the larynx;
forms by its reduplication the chief part of the superior or false vocal cord; and,
from the -ventricle, is continued into the sacculus laryngis. It is then reflected
over the true vocal cords, where it is thin and very intimately adherent; covers
the inner surface of the crico-thyroid membrane and cricoid cartilage; and is
ultimately continuous with the lining membrane of the trachea. The forepart of
the anterior surface and the upper half of the posterior surface of the epiglottis,
the upper part of the aryteno-epiglottidean folds, and the true vocal cords are
covered by stratified squamous epithelium; the rest of the laryngeal mucous
membrane is covered by columnar ciliated cells.
The mucous membrane above the rima glottidis is extremely sensitive, and
during life the lightest touch of a foreign body produces cough.
Glands. — The mucous membrane of the larynx is furnished with numerous
muciparous glands, the orifices of which are found in nearly every part; they
are very numerous upon the epiglottis, being lodged in little pits in its substance;
they are also found in large numbers along the posterior margin of the aryteno-
epiglottidean fold, in front of the arytenoid cartilages, where they are termed the
THE LARYXX
1383
arytenoid glands. They exist also in large numbers upon the inner surface of the
sacculus laryngis. None are found on the surface of the true vocal cords.
Vessels and Nerves. — The arteries of the larynx (Fig. 990) are the laryngeal
branches derived from the superior and inferior thyroid. The superior laryngeal artery
from the superior thyroid courses along by the internal laryngeal nerve; the inferior
laryngeal artery from the inferior thyroid courses along with the recurrent laryngeal
nerve. The veins accompany the arteries; those accompanying the superior laryn-
geal artery join the superior thyroid vein which opens into the internal jugular
vein; while those accompanying the inferior laryngeal artery join the inferior
thyroid vein which opens into the innominate vein. The laryngeal lymphatics arise
from a network in the mucous membrane. This network is divisible into two
portions, a superior and an inferior, which are to be regarded as almost inde-
pendent areas. The superior region includes all of the "laryngeal mucous
membrane above the glottis, epiglottis, aryteno-epiglottidean folds, interarytenoid
region^ and superior vocal cords."1 The inferior area is the laryngeal mucous
Superior
thyroid
artery.
Superior
laryngeal
artery.
FIG. 990. — The origin and distribution of the arteries of the larynx. (Luschka.)
membrane below the glottis. The lymphatics of one-half of the larynx do nut
communicate with those of the other half in the median line in front, but do
in the median line behind. The efferent vessels from the superior network
accompany the superior laryngeal artery, pierce the thyro-hyoid membrane,
and divide into three sets. One or two lymphatic vessels pass upward and
terminate in a gland slightly below the posterior belly of the Digastric muscle.
A group of vessels passes horizontally outward to terminate in the glands
situated on the internal jugular vein on a level with the bifurcation of the
common carotid artery. Another group descends and empties into the internal
jugular group of glands at a lower level than the horizontal vessels. Trunks from
the inferior network of the laryngeal mucous membrane form two groups. The
anterior or supracricoid group consists of three trunks which pass through thecrico-
thyroid membrane, to empty into the pre-laryngeal glands, the pre-tracheal gland,
and the middle and lower deep cervical glands.2 The posterior group consists
1 Philip R. W. De Santi in the Lancet, June 18, 1904.
Poirier, Cuntio, Most, De Santi.
1384 THE ORGANS OF VOICE AND RESPIRATION
of "from three to five trunks, which pass over the crico-tracheal fascia at the
junction of the lateral and posterior aspects of the trachea,"1 and terminate in
the recurrent glands about the recurrent laryngeal nerve. The nerves are derived
from the internal and external laryngeal branches of the superior laryngeal nerve,
from the inferior or recurrent laryngeal, and from the sympathetic. The internal
laryngeal nerve is almost entirely sensor, but some motor filaments are said to be
carried by it to the Arytenoideus muscle. It divides into a branch which is dis-
tributed to both surfaces of the epiglottis, a second to the aryteno-epiglottidean
folds, and a third, the largest, which supplies the mucous membrane over the
back of the larynx and communicates with the recurrent laryngeal. The external
laryngeal nerve supplies the Crico-thyroid muscle. The recurrent laryngeal
passes upward under the lower border of the Inferior constrictor, and enters the
larynx between the cricoid and thyroid cartilages. It supplies all the muscles of
the larynx except the Crico-thyroid and part of the Arytenoideus. The sensor
branches of the laryngeal nerves form subepithelial plexuses, from which fibres
ascend to end between the cells covering the mucous membrane.
Over the posterior surface of the epiglottis, in the aryteno-epiglottidean folds,
and less regularly in some other parts, taste-buds, similar to those in the tongue,
are found.
THE TRACHEA AND BRONCHI (Fig. 991).
The trachea or windpipe is a cartilaginous membranous, elastic, cylindrical
tube, flattened posteriorly, which extends from the lower part of the larynx, on a
level with the sixth cervical vertebra, to opposite the body of the fourth, or some-
times of the fifth, thoracic vertebra, where it divides (bifurcatio tracheae) into two
bronchi, one for each lung. This point is at the level of the spine of the fourth
thoracic vertebra. The trachea is found to be more deeply placed the lower down
it is examined. It is in the median line, deviating below a very little to the right
side. When a cross-section is made of the trachea it is seen that its anterior and
lateral walls are rounded, but its posterior wall is flat (Fig. 995). The largest
diameter of the tube is the middle; from this point the diameter diminishes toward
the bronchi and toward the laryngeal end. The trachea measures about four
inches and a half in length; its diameter from side to side is from three-quarters
of an inch to an inch, being always greater in the male than in the female.
Relations. — The anterior surface of the trachea is convex, and covered in the
neck, from above downward, by the isthmus of the thyroid gland, the inferior
thyroid veins, the arteria thyroidea ima (when that vessel exists), the Sterno-hyoid
and Sterno-thyroid muscles, the cervical fascia, and more superficially, by the
anastomosing branches between the anterior jugular veins: in the thorax it is
covered from before backward by the first piece of the sternum, the remains of the
thymus gland, the left innominate vein, the arch of the aorta, the innominate and
left common carotid arteries, and the deep cardiac plexus. Posteriorly, it is in
relation with the oesophagus ; laterally, in the neck, it is in relation with the com-
mon carotid arteries, the lateral lobes of the thyroid 'gland, the inferior thyroid
arteries, and recurrent laryngeal nerves; and, in the thorax, it lies in the upper
part of the interpleural space, that is, in the superior mediastinum, and is in relation
on the right to the pleura and right vagus, and near the root of the neck to the
innominate artery; on its left side are the recurrent laryngeal nerve, the aortic
arch, the left common carotid and subclavian arteries.
The Right Bronchus (bronchus dexter). — The unbranched portion of the right
.bronchus is wider, shorter, and more vertical in direction than the left, is about
an inch in length, and enters the hilum of the right lung opposite the fifth thoracic
i De Santi, in the Lancet, June 18, 1904.
THE TRACHEA AND BRONCHI
1385
vertebra. It forms an angle to the median plane of about 29 degrees. The vena
azygos major arches over it from behind ; and the right pulmonary artery lies below
and then in front of it. About three-quarters of an inch from its commencement
it gives off a branch to the upper lobe of the right lung. This is termed the
eparterial branch (ramus bronchialis eparterialis] , because it is given off above
the right pulmonary artery. The bronchus now passes below the artery, and is
Superior
Cornu.
Inferior
Cornu.
FIG. 991. — Front view of cartilages of larynx; the trachea and bronchi (the right bronchus is not shown as
steep as it really is.
known as the hyparterial branch (ramus branchialis hyparterialis). It divides
into two branches for the middle and lower lobs.
If a transverse section of the trachea is made a short distance above its point
of bifurcation, and a bird's-eye view taken of its interior (Fig. 995), the septum
placed at the bottom of the trachea and separating the two bronchi will be seen
to occupy the left of the median line, and the right bronchus appears to be a
more direct continuation than the left, so that any solid body dropping into the
trachea would naturally be directed toward the right bronchus. This tendency is
aided by the larger size of the right tube as compared with its fellow. This fact
1386
THE ORGANS OF VOICE AND RESPIRATION
serves to explain why a foreign body in the trachea more frequently falls into the
right bronchus than into the left.1
The Left Bronchus (bronchus sinister}. — The left bronchus is smaller and
longer than the right, being nearly two inches in length. It forms an angle to the
median plane of about 46 degrees. It is slightly
curved and enters the root of the left lung, oppo-
site the sixth thoracic vertebra, about an inch
lower than the right bronchus. It passes be-
neath the arch of the aorta, crosses in front of
the oesophagus, the thoracic duct, and the de-
scending aorta, and has the left pulmonary artery
lying at first above, and then in front of it. The
left bronchus has no branch corresponding to
the eparterial branch of the right bronchus, and
therefore it has been supposed by some that
there is no upper lobe to the left lung, but that
the so-called upper lobe corresponds to the
middle lobe of the right lung. The left bron-
chus does have an hyparterial branch.
When the main or stem bronchus enters the
lung on each side it appears to divide into nearly
equal branches at the root of the lung, but a
somewhat similar arrangement to what is found
in many animals may be made out where each
main bronchus passes downward and backward
toward the extremity of the lower lobe, and ends
near the posterior surface of the base of the lung,
a portion of pulmonary substance which is be-
tween the Diaphragm and the wall of the chest.
It gives off four branches, or lateral bronchi
(rami bronchioles), at intervals in two directions, dorsally and ventrally, and, in
addition, accessory branches, which arise from the front of the bronchus and
pass mesally and dorsally into the inferior lobe. In the right bronchus the
first ventral branch supplies the middle lobe, the other three and all the dorsal
going to the lower lobe; in the left bronchus, the first ventral branch sup-
plies the middle lobe, the other three and all the dorsal going to the lower
lobe; in the left bronchus, the first central supplies the superior lobe, and all the
others, both ventral and dorsal, go to the lower lobe. The dorsal and ventral
branches divide into smaller branches, and these again into smaller branches or
bronchioles (Fig. 994). Each bronchiolus divides into minute branches (bronchioli
respiratorii) (Fig. 994), the walls of which show numerous areas of bulging called
alveoli (Fig. 994). From the bronchioli respiratorii come the terminal branches
of the bronchi. These terminal branches are the alveolar ducts (ductuli alveolares),
and they are bulged by numerous alveoli (Fig. 994). They connect by openings
at their termination with several cavities of irregular form, which are called atria.
Each atrium is connected with several or many larger cavities, known as sacculi
alveolares, air-cells, or air-sacs (infundibula). The entire surface of the air-sacs is
filled with small cavities, the pulmonary alveoli (alveoli pulmonis). An alveolar
duct with its branches forms a pulmonary lobule (lobulus pulmonis) (Fig. 993).
Structure of the Trachea. — The trachea is composed of imperfect cartilagi-
nous rings, fibrous membrane, muscular fibres, mucous membrane, and glands.
The Cartilages. — The cartilages vary from sixteen to twenty in number; 'each
forms an imperfect ring, which surrounds about two-thirds of the cylinder of the
1 Reigel asserts that the entrance of a foreign body into the left bronchus is by no means so infrequent as is
generally supposed. See also Med.-Chir. Transactions, vol. Ixxi., p. 121. — ED. of 15th English edition.
FIG. 992. — Internal surface of the bronchi.
(Poirier and Charpy.)
THE TRACHEA AND BRONCHI
1387
trachea, being imperfect behind, where the tube is completed by fibrous mem-
brane. The cartilages are placed horizontally above each other, separated by
narrow membranous intervals. They measure about two lines in depth, and half
a line in thickness. Their outer surfaces are flattened, but internally they are
convex, from being thicker in the middle than at the margins. Two or more of
the cartilages often unite, partially or completely, and are sometimes bifurcated
at their extremities. They are highly elastic, but sometimes become calcified in
advanced life. In the right bronchus the cartilages vary in number from six to
eight; in the left, from nine to twelve. They
are shorter and narrower than those of the
trachea. The peculiar cartilages are the first
and the last.
The First Cartilage is broader than the rest,
and sometimes divided at one end; it is con-
nected by fibrous membrane with the lower
NTERLOBULAR
ALVEOLI
DUCT
BRONCHIOLE
RESPIRATORY
BRONCHIOLE
FIG. 993. — A pulmonary lobule. (Poirier and
Charpy.)
FIG. 994. — The terminal bronchial tubes. The respiratory
bronchiole and alveoli. (Poirier and Charpy.)
Left.
border of the cricoid cartilage, with which or with the succeeding cartilage it is
sometimes blended.
The Last Cartilage is thick and broad in the middle, in consequence of its lower
border being prolonged into a triangular hook-shaped process which curves down-
ward and backward between the two bronchi. It terminates on each side in an
imperfect ring which encloses the com-
mencement of the bronchi. The cartil-
age above the last is somewhat broader
than the rest at its centre.
The Fibrous Membrane. — The cartil-
ages are enclosed in an elastic fibrous
membrane which forms a double layer,
one layer, the thicker of the two, passing
over the outer surface of the ring, the
other over the inner surface; at the
upper and lower margins of the cartilages
these two layers blend together to form a
single membrane, which connects the rings one with another. They are thus, as
it were, embedded in the membrane. In the space behind, between the extremi-
ties of the rings, the membrane forms a single distinct layer.
The Muscular Fibres. — The muscular fibres are disposed in two layers, longi-
tudinal and transverse
FIG. 995. — Transverse section of the trachea, just
above its bifurcation, with a bird's-eye view of the
interior.
1388
THE ORGANS OF VOICE AND RESPIRATION
The Longitudinal Fibres are the most external, and consist merely of a few scat-
tered longitudinal bundles of fibres.
The Transverse Fibres constitute the Trachealis muscle of Todd and Bowman. The
most internal form a thin layer which extends transversely between the ends of
the cartilages and the intervals between them at the posterior part of the trachea.
The muscular fibres are of the unstriped variety.
The Mucous Membrane. — The mucous membrane is continuous above with that
of the larynx, and below with that of the bronchi. Microscopically, it consists of
areolar and lymphoid tissue, and presents a well-marked basement-membrane,
supporting a layer of columnar, ciliated epithelium, between the deeper ends of
which are smaller triangular cells, the bases of which, often branched, are attached
to the basement-membrane. These triangular cells are mucus-secreting, and may
be seen as goblet-cells or chalice-cells when their contents have been discharged.
In the deepest part of the mucous membrane, and especially between the mucous
and subrnucous layers, longitudinally arranged fibres are very abundant and form
a distinct layer.
The Tracheal Glands (glandulae tracheales). — The trachea! glands are found in
great abundance at the posterior part of the trachea. They are racemose glands,
and consist of a basement-membrane lined by columnar mucus-secreting cells.
They are situated at the back of the trachea, outside the layer of muscular tissue,
between it and the outer fibrous layer. Their excretory ducts pierce the muscular
and inner fibrous layers, and pass through the submucous and mucous layers to
open on the surface of the mucous membrane. Some glands of smaller size are
also found at the sides of the trachea, between the layers of fibrous tissue con-
necting the rings, and others immediately beneath the mucous coat. The secre-
tion from these glands serves to lubricate the inner surface of the trachea.
RIGHT TRACHEAL
LYMPH GLAND
RIGHT SUPERIOR
TRACHEO-
BRONCHIAL
LYMPH GLAND
LEFT TRACHEAL
LYMPH GLAND
LEFT SUPERIOR
TRACHEO-
BRONCHIAL
LYMPH GLAND
Vl
BRONCHO-
PULMONARY
LYMPH GLAND
INFERIOR
TRACHEO- BRONCHIAL
LYMPH GLAND
FIG. 996.— The tracheo-bronchial and broncho-pulmonary lymphatic glands, seen from in front. The pointed
(?) lymphatic glands and lymph-vessels are not visible from in front: d\, rf.j, first and second dorsal bronchial
branches; n, ?>;, first and second ventral bronchial branches. (Sukiennikow.)
Vessels and Nerves. — The trachea is supplied with blood by the inferior thy-
roid arteries. The veins terminate in the thyroid venous plexus. The nerves
are derived from the vagus and its recurrent branches and from the sympathetic.
THE TRACHEA AND BRONCHI 1389
Lymphatic Glands. — The trachea is surrounded by lax connective tissue which
contains numerous lymph glands, known as the peritracheo-bronchial glands. They
are divided into four groups (Bare"ty). A group to the right side, in the angle
between the trachea and right bronchus and ascending to the region of the sub-
clavian vessels. A group to the left side, in the angle formed by the trachea and
left bronchus, and ascending to about the arch of the aorta a^d the recurrent
laryngeal nerve. The two groups just described are usually calle^ trackeal glands
(lymphoglandidae tracheales). A third group is in the angle formea by the bifur-
cation of the trachea. These constitute the bronchial glands (lymphoglandidae
bronchioles}. They number ten or twelve (Cune"o). A fourth group, the inter-
bronchial glands, are found in angles of bifurcation of the larger bronchi in the
lung parenchyma. Very early in life the peritracheo-bronchial glands become
dark or even black from the deposition of carbonaceous substance brought by
the leukocytes from the bronchial tubes. This condition is called anthracosis.
Surface Form. — In the middle line of the neck some of the cartilages of the larynx can readily
be distinguished. In the receding angle below the chin the hyoid bone can easily be made
out, and a finger's breadth below it is the pomum Adami, the prominence between the upper
borders of the two alae of the thyroid cartilage. About an inch below this, in the middle line, is
a depression corresponding to the crico-thyroid space, in which the operation of laryngotomy is
performed. This depression is bounded below by a prominent arch, the anterior ring of the
cricoid cartilage, below which the trachea can be felt, though it is only in the emaciated adult
that the separate rings can be distinguished. The lower part of the trachea is not easily made
out, for as it descends in the neck it takes a deeper position, and is farther removed from the
surface. The level of the vocal cords corresponds to the middle of the anterior margin of the
thyroid cartilage.
With the laryngoscope, the following structures can be seen: The base of the tongue and
the upper surface of the epiglottis, with the glosso-epiglottic ligaments; the superior aperture of
the larynx, bounded on either side by the aryteno-epiglottidean folds, in which may be seen two
rounded eminences corresponding to the cornicula and cuneiform cartilages. Beneath these, the
true and false vocal cords, with the ventricle between them. Still deeper, the cricoid cartilage
and some of the anterior parts of the rings of the trachea, and sometimes, in deep inspiration, the
bifurcation of the trachea.
Surgical Anatomy. — Foreign bodies often find their way into the air-passages. These may
be either large soft substances, as a piece of meat, which may become lodged in the upper aper-
ture of the larynx or in the rima glottidis, and cause speedy suffocation unless rapidly got rid of,
or unless an opening is made into the air-passages below, so as to enable the patient to breathe.
Smaller bodies, frequently of a hard nature, such as cherry- or plum-stones, small pieces of bone,
buttons, etc., may find their way through the rima glottidis into the trachea or bronchus, or may
become lodged in the ventricle of the larynx. The dangers then depend not so much upon the
mechanical obstruction as upon the spasm of the glottis which they excite from reflex irritation.
When lodged in the ventricle of the larynx, they may produce very few symptoms beyond sudden
loss of voice or alteration in the voice sounds, immediately following the inhalation of the foreign
body. When, however, they are situated in the trachea, they are constantly striking against
the vocal cords during expiratory efforts, and produce attacks of dyspnoea from spasm of the
glottis. When lodged in the bronchus, they usually become fixed there, and, occluding the
lumen of the tube, cause a loss of the respiratory murmur on the affected side, which is, as stated
above, more often the right.
Beneath the mucous membrane of the upper part of the air-passages there is a considerable
amount of submucous tissue which is liable to become much swollen from effusion in inflamma-
tory affections, constituting the disease known as " oedema of the glottis." This effusion does
not extend below the level of the true vocal cords, on account of the fact that the mucous mem-
brane is closely adherent to these structures, without the intervention of any submucous tissue.
So that, in cases of this disease in which it is necessary to open the air-passages to prevent suffo-
cation, the operation of laryngotomy is sufficient.
Chronic laryngitis is an inflammation of the mucous glands of the larynx, which occurs in
those who speak much in public, and is known as " clergyman's sore throat." It is due to the
dryness induced by the large amount of cold air drawn into the air-passages during prolonged
speaking, which incites increased activity in the mucous glands to keep the parts moist, and
this eventually terminates in inflammation of these structures.
Ulceration of the larynx may occur from syphilis, either as a superficial ulceration, or from
the softening of a gumma; from tuberculous disease (laryngeal phthisis), or from malignant
disease (epithelioma).
1390 THE ORGANS OF VOICE AND RESPIRATION
The air-passages may be opened surgically in two different situations: through the crico-
thyroid membrane (laryngotpmy) , or in some part of the trachea (tracheotomy); and to these
some surgeons have added a third method, by opening the crico-thyroid membrane and
dividing the cartilage with the upper ring of the trachea (laryn go-tracheotomy).
Laryngotomy is anatomically the more simple operation: it can readily be performed, and
should be employed in those cases where the air-passages require opening in an emergency for
the relief of some sudden obstruction to respiration. The crico-thyroid membrane is very
superficial, being covered only in the middle line by the skin, superficial fascia, and the deep
fascia. On each side of the middle line it is also covered by the Sterno-hyoid and Sterno-thyroid
muscles, which diverge from each other at their upper parts, leaving a slight interval between
them. On these muscles rest the anterior jugular veins. The only vessel of any importance
in connection with this operation is the crico-thyroid artery, which crosses the crico-thyroid
membrane, and which may be wounded, but rarely gives rise to any trouble. The operation
is performed thus: the head being thrown back and steadied by an assistant, the finger is passed
over the front of the neck, and the crico-thyroid depression felt for. A vertical incision is then
made through the skin, in the middle line over this spot, and carried down through the fascia
until the crico-thyroid membrane is exposed. A cross-cut is then made through the membrane,
close to the upper border of the cricoid cartilage, so as to avoid, if possible, the crico-thyroid
artery, and a tracheotomy tube is introduced. It has been recommended, as a more rapid way
of performing the operation, to make a transverse instead of a longitudinal cut, through both the
superficial and deep structures, and thus to open at once the air-passages. It will be seen, however,
that in opening in this way the anterior jugular veins would be in danger of being wounded.
Tracheotomy may be performed either above or below the isthmus of the thyroid body, or
this structure may be divided and the trachea opened behind it.
The isthmus of the thyroid gland usually crosses the second and third rings of the trachea;
along its upper border is frequently to be found a large transverse communicating branch between
the superior thyroid veins; and the isthmus itself is covered by a venous plexus formed between
the thyroid veins of the opposite sides. Theoretically, therefore, it is advisable to avoid dividing
this structure in opening the trachea.
Above the isthmus the trachea is comparatively superficial, being covered by the skin, super-
ficial fascia, deep fascia, Sterno-hyoid and Sterno-thyroid muscles, and a second layer of the
deep fascia, which, attached above to the lower border of the hyoid bone, descends beneath the
muscles to the thyroid body, where it divides into two layers and enclose the isthmus.
Below the isthmus the trachea lies much more deeply, and is covered by the Sterno-hyoid
and the Sterno-thyroid muscles and a quantity of loose areolar tissue in which is a plexus of
veins, some of them of large size; they converge to two trunks, the inferior thyroid veins, which
descend on either side of the median line on the front of the trachea and open into the innomi-
nate veins. In the infant the thymus gland ascends a variable distance along the front of the
trachea, and opposite the episternal notch the windpipe is crossed by the left innominate vein.
Occasionally, also, in young subjects, the innominate artery crosses the tube obliquely above
the level of the sternum. The thyroidea ima artery, when that vessel exists, passes from below
upward along the front of the trachea.
From these observations it must be evident that the trachea can be more readily opened
above than below the isthmus of the thyroid body.
Tracheotomy above the isthmus is performed thus, the patient should, if possible, be laid
on his back on a table in a good light. A pillow is to be placed under the shoulders and the
head thrown back and steadied by an assistant. The surgeon standing on the right side of his
patient makes an incision from an inch and a half to two inches in length in the median line of
the neck from the top of the cricoid cartilage. The incision must be made exactly in the middle
line, so as to avoid the anterior jugular veins, and after the superficial structures have been
divided the interval between the Sterno-hyoid muscles must be found, the raphe divided, and
the muscles drawn apart. The lower border of the cricoid cartilage must now be felt for, and
the upper part of the trachea exposed from this point downward in the middle line. Bose has
recommended that the layer of fascia in front of the trachea should be divided transversely at
the level of the lower border of the cricoid cartilage, and, having been seized with a pair of
forceps, pressed downward with the handle of the scalpel. By this means the isthmus of the
thyroid gland is depressed, and is saved from all danger of being wounded, and the trachea is
cleanly exposed. The trachea is now transfixed with a sharp hook and drawn forward in order
to steady it, and is then opened by inserting the knife into it and dividing the two or three upper
rings from below upward. If the trachea is to be opened below the isthmus, the incicion to
expose it must be made from a little below the cricoid cartilage to the top of the sternum.
In the child the trachea is smaller, more deeply placed, and more movable than in tho adult.
In fat or short-necked people, or in those in whom the muscles of the neck are prominently
developed, the trachea is more deeply placed than in others.
A portion of the larynx or the whole of it has been removed or malignant disease, laryn-
(jectomy.
THE PLEURAE
1391
Some surgeons do preliminary tracheotomy, insert a Trendelenburg cannula to prevent the
flow of blood downward into the lungs, and then remove the larynx. Other surgeons do not
employ preliminary tracheotomy.
Perier's method of laryngectomy is as follows: Make a vertical incision in the median line
from the level of the hyoid bone to below the level of the cricoid cartilage. Make a transverse
incision at each end of the vertical incision. This makes an I-shaped wound.
Separate the soft parts from the larynx and upper part of the trachea, and separate these two
structures from the oesophagus. After arresting bleeding, divide the trachea below the cricoid
cartilage, introduce a special cinnula, complete the removal of the larynx, suture the opening of
the trachea to the lower nngleof the wound, and close the rest of the wound after securing drainage.
In malignant disease of the larynx the associated lymphatic glands must be removed.
Partial laryngectomy, according to Sir F. Semon, is the removal of not less than one wing of
the thyroid cartilage. Removal of a lesser piece of the thyroid or of a bit of the arytenoid or
cricoid he considers with the operation of thyrotomy.
THE PLEURAE (Figs. 997, 998, 999, 1000, 1001).
Each lung is invested, upon its external surface, by an exceedingly delicate
serous membrane, the pleura, which encloses the organ as far as its root, and is
then reflected upon the inner surface of the thorax. The portion of the serous
membrane investing the surface of the lung and dipping into the fissures between
its lobes is called the pulmonary pleura or the visceral layer of the pleura (pleura
pulmonalis)(Fig. 997), while that which lines the inner surface of the chest is called
the parietal layer of the pleura (pleura parietalis) (Fig. 997). The two layers join at
the hilum of the lung. The space between these two layers is called the cavity of the
pleura (cavum pleurae), and contains a very little clear fluid. It must be borne
in mind that in the healthy condition the two layers are in contact, and there
TRIANGULARIS STERN).
Internal Mammary Vessels.
Left Phrenic Nerve
Pleura Pulmonalis.
Pleura Costalis.
Mediastinum
\ Vena A*yffO» Major ) Pof(erior
Vagus Venn >
FIG. 997. — A transverse section of the thorax, showing the relative position of the viscera and the
reflections of the pleurae.
is no real cavity until the lung becomes collapsed and separates from the wall
of the chest. Each pleura is therefore a shut sac, one occupying the right, the
other the left half of the thorax, and they are perfectly separate from each other.
1392
THE ORGANS OF VOICE AND RESPIRATION
The two pleurae do not meet in the middle line of the chest, excepting anteriorly
opposite the second and third pieces of the sternum — a space being left between
them, which contains all the viscera of the thorax excepting the lungs; this is the
mediastinum.
SCALCNUS
MINIMUS
SYMPATHETIC
GANGLION
FIG. 998. — The dome of the pleura (Poirier and Charpy.)
Reflections of the Pleurae (Fig. 997). The Pleura Pulmonalis (Fig. 997).— The
pleura pulmonalis is closely attached to the surface of the lung and enters into the
depths of the interlobar fissures. It leaves the lung surface at the hilum, covers the
COSTA PLED RAL
LIGAMENT
SCALENUS
MINIMUS
MUSCLE
„ FIG. 999. — The supports of the pleural dome. The oesophagus, trachea, and arteries have been cut and pulled
aside to show the pleural reinforcements. (Poirier and Charpy.)
root of the lung for a little way (Fig. 1004 and 1005), and then passes into the medi-
astinal pleura. Between the hilum and the mediastinal pleura there is a thickened
pleural fold, triangular in outline, and called the ligamentum pulmonale or the
ligamentum latum pulmonis (Figs. 1004 and 1005). It is formed by the two layers of
THE PLEURAE
1393
the pulmonary pleura coming in contact below the root of the lung. This fold
passes from the lower part of the inner pulmonary surface to the -pericardium,
and the lower border is free or attached to the diaphragmatic pleura. In the
right lung the origin of this ligament is in front of the groove for the azygos vein;
in the left lung it is in front of the groove for the thoracic aorta.
The Pleura Parietalis. — The pleura parietalis is a continuous membrane, but
for convenience is divided into the cervical pleura, costal pleura, mediastinal pleura,
and diaphragmatic pleura.
The Cervical Pleura or Dome of the Pleura or Cupola (cupula pleurae} (Fig. 1000) is
the dome-shaped roof of the cavity of the pleura. It projects above the apex of the
lung to the neck of the first rib. As the first rib is placed obliquely, the dome of the
pleura reaches from one to one and one-half inches above the anterior extremity of
the first rib, and from one-half an inch to one inch above the clavicle. On the
outer side of the cervical pleura are the Scalenus anticus and medius muscles. Just
SYMPATHETIC
GANGLION
FIRST
THORACIC
NERVE
SIXTH
RIB
I.ONGUS COLL!
MUSCLE
.SIBSON'S
APONEUROSIS
HRENICO-
OSTAL SINUS
CELLULAR
TISSUE
DIAPHRAGM
^
FIG. 1001. — Section of the wall of the
FIG. 1000. — The supports of the pleural dome. (Poirier and thorax, showing the phrenico-costal sinus.
Charpy.) (Poirier and Charpy..)
(Poirier and Charpy.)
below the apex, on the anterior and inner surface, is a groove for the subclavian
artery, which vessel passes over it in an arch (Fig. 998). A little below the groove
for the subclavian artery is a broader and shallower groove for the innominate and
subclavian veins. Above the subclavian artery and in front and above the cervical
pleura are the cords of origin of the brachial plexus and the inferior cervical gan-
glion (Fig. 998). The dome is strengthened and kept in place by Sibson's aponeu-
rosis or the vertebro-pleural ligament (Figs. 999 and 1000). This comes from a little
piece of muscle, the Scalenus minimus muscle, which originates from the transverse
process of the seventh cervical vertebra, broadens and becomes aponeurotic as it
descends, and is inserted into the inner margin of the first rib (Figs. 998 and 999).
It is also strengthened by the costo-pleural ligament (Fig. 999), from the inner sur-
face of the neck of the first rib to the pleura, and by fibrous bands which pass to the
tissue about the subclavian sheath, trachea, and oesophagus (Fig. 999).
The Costal Pleura (pleura costalis] (Fig. 997) is the shortest portion of the
pleura and is connected to the parts it covers by the endothoracic fascia (fascia
1394 THE ORGANS OF VOICE AND RESPIRATION
endothoracica) , a layer of connective tissue which is much thicker back of the rib
cartilages than it is posteriorly. The costal pleura covers the inner surface of part
of the sternum, the costal cartilages, ribs, and Intercostal muscles, and the sides
of the bodies of the thoracic vertebrae. This layer is loosely attached except as it
passes from the heads of the ribs to the vertebrae, where it is firmly adherent.
The Mediastinal Pleura (pleura mediastinalis] (Fig. 999) covers the septum of the
mediastinum, which intervenes between the two pleural cavities. The mediastinal
pleura extends from the inner surface or the anterior wall of the thorax to the
vertebrae. It is continuous in front and back with the costal pleura of the same
side, the lines of junction being known, respectively, as the anterior line of pleural
reflection and the posterior line of pleural reflection. Below the mediastinal pleura
passes into the diaphragmatic pleura of the same side. The portion of the medi-
astinal pleura which fuses with the parietal layer of the pericardium is called the
pericardial pleura (pleura pericardiaca).
Above the root of the lung the mediastinal pleura passes back directly to the
vertebrae. " In this region the left mediastinal pleura is applied to the arch of the
aorta and the phrenic and vagus nerves; to the left innominate vein, the left
superior intercostal vein, and. the left common carotid and left subclavian arteries;
to the oesophagus and the thoracic duct. The right mediastinal pleura, on the other
hand, is applied, above the level of the root of the lung, to the upper part of the
precava and right innominate vein; to the right innominate artery; to the vena
azygos major, as it hooks forward above the bronchus; to the vagus and phrenic
nerves; and to the right side of the trachea."1 Upon the pericardium the phrenic
nerve is covered by the pleura. Back of the root of the lung and the pulmonary
ligament, the right mediastinal pleura passes back to the vertebrae to the left of the
oesophagus; the left mediastinal pleura passes back over the descending aorta,
and just above the Diaphragm and in front of the aorta over the lower end of the
oesophagus.
The Diaphragmatic Pleura (pleura diaphragmatica) (Figs. 1001 and 1002) covers
the upper surface of the Diaphragm outside of the base of the pericardium, but
does not completely cover it; for it does not pass into the interval between the
wall of the thorax and Diaphragm, and before this point is reached becomes
continuous with the costal pleura.
The reflection to the costal pleura begins by the sternum, at the lower margin of
the sixth rib ; takes place at the junction of the cartilage of the rib with the seventh
rib; posteriorly, it takes place at the lower margin of the twelfth thoracic vertebra.
In the front of the chest, where the parietal layer of the pleura is reflected back-
ward to the pericardium, the two pleural sacs are in contact for a considerable
extent. At the upper part of the chest, behind the manubrium, they are not in
contact; the point of reflection being represented by a line drawn from the sterno-
clavicular articulation to the mid-point of the junction of the manubrium to the
body of the sternum. From this point the two pleurae descend in close contact to
the level of the fourth costal cartilages Here the line of reflection on the right side
is continued downward in nearly a straight line to the lower end of the gladiolus and
then turns outward behind the costal cartilage of the sixth rib, continuing to
descend and to run outward, it passes behind the descending part of the seventh
costal cartilage, and meets the axillary line at the junction of the eighth rib with
the cartilage. The line of reflection continues to descend till it reaches its lowest
point at the tenth rib. This point is in the axillary line, while on the left side
the line of reflection diverges outward, so that opposite the seventh cartilage it is
about three-quarters of an inch from the left border of the sternum. It, how-
ever, always extends considerably farther over the pericardium than the corre-
sponding lung. From this joint the reflections of the two sides are practically
1 Cunningham's Text-book of Anatomy.
THE PLEURAE 1395
•
the same. The lower limit of the pleura is on a considerably lower level than
the lower limit of the lung, but does not extend to the attachment of the Dia-
phragm, so that below the line of reflection of the pleura from the chest wall
on to the Diaphragm the latter is in direct contact with the rib cartilages and
the Internal intercostal muscles. In ordinary inspiration the thin margin of the
base of the lung does not extend as low as the line of pleural reflection, with the
result that the costal and diaphragmatic pleura are here in contact, the narrow
slit between the two being termed the phrenico-costal sinus (sinus phrenicocos-
talis) (Fig. 1001). A similar condition exists behind the sternum and rib cartilages,
where the anterior thin margin of the lung falls short of the line of pleural reflec-
tion, and where the slit-like cavity between the two layers of pleura forms what is
sometimes called the costo-mediastinal sinus (sinus costomediastinalis) .
Along the line of reflection of the diaphragmatic pleura a dense fascia passes
from the costal cartilages and the uncovered portion of the Diaphragm to the
costal pleura. This serves to hold it in place. It is named by Cunningham the
phrenico -pleural fascia.
The inner surface of the pleura is smooth, polished, and moistened by a serous
fluid; its outer surface is intimately adherent to the surface of the lung, and to the
pulmonary vessels as they emerge from the pericardium; it is also adherent to the
upper surface of the Diaphragm; throughout the rest of its extent it is somewhat
thicker, and may be separated from the adjacent parts with extreme facility.
The right pleural sac is shorter, wider, and reaches higher in the neck than
the left.
Structure of the Pleura. — The pleura is composed of connective tissue con-
taining much elastic tissue, its free surface being covered with flat endothelial cells.
It is fastened to adjacent structures by subserous areolar tissue. The subserous
tissue of the visceral pleura is continuous with the areolar tissue of the lung.
Vessels and Nerves. — The arteries of the pleura are derived from the intercostal,
the internal mammary, the musculo-phrenic, thymic, pericardiac, and bronchial.
The veins correspond to the arteries. The lymphatics are very numerous in the
pleura and subserous tissue. Many of them are in direct communication with the
pleural cavity by stomata between the endothelial cells. Stomata are absent in
the mediastinal pleura and over the ribs (Dyskowsky). The lymphatics of the
visceral layer empty into the superficial pulmonary trunks ; the lymphatics of the
costal pleura empty into the intercostal trunks; of the diaphragmatic pleura, into
the diaphragmatic trunks; of the mediastinal pleura, into the posterior mediastinal
glands.1 The nerves are derived from the phrenic and sympathetic (Luschka).
Kolliker states that nerves accompany the ramification of the bronchial arteries
in the pleural pulmonalis.
Surgical Anatomy. — In operations upon the kidney it must be borne in mind that the pleura
may sometimes extend below the level of the last rib, and may therefore be opened in these
operations, especially when the last rib is removed, in order to give more room. It is best to
keep the incision at least one inch below the last rib, enlarging the wound afterward, when the
finger can be introduced as a guide.
In wounds of the Diaphragm the pleura may be injured. In operations about the root of
the neck, especially in the removal of glands and the ligation of the first part of the subclavian
artery, the pleura may be injured.
Punctured wounds of the root of the neck are apt to reach the pleura.
Empyema is a surgical disease. In acute empyema the treatment is drainage. A portion of
the fifth or sixth rib in the axillary line is removed by subperiosteal resection, the pleura is
opened, and a tube is introduced. In chronic empyema the lung is contracted and adherent and
cannot expand; hence drainage will not cure it. It is necessary to perform multiple rib resec-
tion in order to permit the chest-wall to sink in and obliterate the cavity, which, as the lung
is unable to expand, it cannot do. The necessary operation may be the operation of Estlander,
or the operation of Schede, or the operation of Fowler (page 168).
, ' Poirier, Cune'o, and Delamare on the Lymphatics. Translated and edited by Cecil H. Leaf.
1396 THE ORGANS OF VOICE AND RESPIRATION
If a large wound admits suddenly a quantity of air into the pleura, dangerous or fatal pneumo-
thorax arises, and the lung collapses. This is usually met during operations by using the Fell-
O1 Dwyer apparatus for artificial respiration as advised by Matas.1 This apparatus keeps the
lung expanded, in spite of the entrance of air into the pleural sac. A surgeon can open the pleura
widely without any fear of the lung collapsing if he operates in a Sauerbruch chamber. The
pressure within this chamber is negative. The patient's head is outside of the chamber, his body is
within it. The bronchioles are distended by the animal inhaling air at the ordinary pressure, but
the exposed lung is subjected to negative pressure, hence the lung does not collapse in spite of a
large wound in the pleura. In surgical pneumothorax the lung may be sutured to the chest-wall,
so as to block the opening. Sometimes, in order to arrest dangerous pulmonary bleeding, a surgeon
deliberately induces pneumothorax, in hope that the collapse of the lung will arrest bleeding.
When an abscess of the liver is posterior and on the dorsum, transpleural hepatotomy is per-
formed. A portion of the tenth and eleventh ribs below the angle of the scapula is removed.
As a rule, the pleura is found obliterated at this point. If it is opened, it is at once sutured or
closed with gauze packing. The exposed Diaphragm is incised, and, as it is usually adherent
to the liver, the abscess cavity is entered. If it is not adherent, the liver is exposed and the
abscess sought for with an aspirating-needle.
THE MEDIASTINAL SPACE, INTERPLEURAL SPACE OR
MEDIASTINUM.
The mediastinum is the space left in the median portion of the chest by the non-
approximation of the two pleurae. It extends from the sternum in front to the
spine behind. Within it are the contents of the thorax excepting the lungs. The
mediastinum may be divided for purposes of description into two parts — an
upper portion, above the upper level of the pericardium, which is named the
superior mediastinum (Struthers); and a lower portion, below the upper level of
the pericardium. This lower portion is again subdivided into three — that part
which contains the pericardium and its contents, the middle mediastinum; that
part which is in front of the pericardium, the anterior mediastinum; and that part
which is behind the pericardium, the posterior mediastinum.
The Superior Mediastinum (Fig. 1003).— The superior mediastinum is that por-
tion of the interpleural space which lies above the upper level of the pericardium
between the manubrium sterni in front and the upper thoracic vertebrae behind. It
is bounded below by a plane passing backward from the junction of the manubrium
and gladiolus sterni to the lower part of the body of the fourth thoracic vertebra,
and laterally by the lungs and pleurae. It contains the origins of the Sterno-hyoid
and Sterno-thyroid muscles and the lower ends of the Longus colli muscles; the
arch of the aorta; the innominate, the thoracic portion of the left carotid and sub-
clavian arteries; the upper half of the precava and the innominate veins, and the
left superior intercostal vein; the vagus, cardiac, phrenic, and left recurrent laryn-
geal nerves; the trachea, oesophagus, and thoracic duct; the remains of the
thymus gland and some lymphatic glands.
The Anterior Mediastinum (Fig. 997).— The anterior mediastinum is bounded
in front by the sternum, on each side by the pleura, and behind by the pericardium.
It is narrow above, but widens out a little below, and, owing to the oblique course
taken by the left pleura, it is directed from above obliquely downward and to the
left. Its anterior wall is formed by the left Triangularis sterni muscle and the
fifth, sixth, and seventh left costal cartilages. It contains a quantity of loose
areolar tissue, some lymphatic vessels which ascend from the convex surface of the
liver, two or three lymphatic glands (anterior mediastinal glands), and the small
mediastinal branches of the internal mammary artery.
The Middle Mediastinum (Fig. 997).— The middle mediastinum is the
broadest part of the interpleural space. It contains the heart enclosed in the
pericardium, the ascending aorta, the lower half of the precava, with the vena
azygos major opening into it, the bifurcation of the trachea and the two bronchi,
» Annals of Surgery, April, 1899.
THE MEDIASTINAL SPACE OR MEDIASTINUM
1397
the pulmonary artery dividing into its two branches and the right and left pul-
monary veins, the phrenic nerves, and some bronchial lymphatic glands.
The Posterior Mediastinum (Figs. 997 and 1001).— The posterior mediastinum
is an irregular triangular space running parallel with the vertebral column; it is
bounded in front by the pericardium and roots of the lungs, behind by the verte-
Fio. 1002. — The posterior mediastinum.
braL column from the lower border of the fourth thoracic vertebra, and on either
side by the pleura. It contains the descending thoracic aorta, the greater and
lesser azygos veins, the vagus and splanchnic nerves, the oesophagus, thoracic
duct, and some lymphatic glands.
Blood-vessels. — The areolar tissue of the anterior mediastinum receives numer-
ous mediastinal branches from the internal mammary artery. The areolar tissue
1398
THE ORGANS OF VOICE AND RESPIRATION
of the posterior mediastinum receives mediastinal branches from the descending
thoracic aorta. The lowest mediastinal vessels lie upon the Diaphragm and are
called superior phrenic arteries. The precava and internal mammary veins receive
mediastinal branches.
Left Inom-
inate Vein.
Left Carotid
Artery.
Thymus
Gland.
Vagus
Nerve.
Internal Mammary
Artery.
Right Innom-
inate Vein.
Vertebral
Artery
Left SuUcaviun,
Artery.
Oesophagus.-'"
V
3rd Rib.
FIG. 1003. — Transverse section through the second thoracic vertebra. (Braune.)
The anterior mediastinal lymphatic glands are in the upper portion of the anterior
mediastinum. They are five or six in number and are placed in front of the trans-
verse arch of the aorta. Chains of glands run up from them to the root of the
neck. On the right side glands are in front of the right innominate vein, between
the artery and vein and behind the artery. On the left side they are around the
left common carotid and left subclavian arteries.1
The posterior mediastinal glands are around the oesophagus, particularly in front
of it. The peritracheo-bronchial glands have been described.
THE LUNGS (PULMONES) (Figs. 997, 1004, 1005, 1006, 1007, 1008, 1009).
The lungs are the essential organs of respiration; they are two in number,
placed one on each side of the chest, separated from each other by the heart and
other contents of the mediastinum. A healthy lung hangs free within the pleural
cavity. It is suspended by the root and by the ligamentum pulmonis. In many
cases examined the lung does not hang free, but, as a result of former pleurisy,
an area of the pulmonary pleura is adherent to the parietal pleura. Each lung is
conical in shape, and presents for examination an apex, a base, two borders, and
two surfaces.
The Apex (apex pulmonis). — The apex forms a tapering cone which extends
into the root of the neck about an inch to two inches above the level of the anterior
extremity of the first rib. The brachial plexus is in close proximity to (his por-
tion of the lung.
The Base (basis pulmonis). — The base is broad, concave, and rests, by its
diaphragmatic surface (fades diaphragmatica) , upon the convex surface of the
1 Poirier, Cuneo, and Delamare on the Lymphatics. Translated and edited by Cecil H. Leaf.
THE LUNGS
1399
Diaphragm, which separates the right lung from the upper surface of the right
lobe of the liver and the left lung from the upper surface of the left lobe of the
liver, the fundus of the stomach, and the spleen; its circumference is thin, and
GROOVE FOR
INNOMINATE VEIN
HILUM
OF LUNG
ANTERIOR
BORDER
LINE OF REFLECTION
OF PULMONARY
PLEURA ON TO
ROOT OF LUNG
LIGAMENTUM
LATUM PULMONIS
FIG. 1004. — The right lung. The inner or mediastinal surface, with the hilum laid bare by the removal of the
structures forming the root of the lung. (Toldt.)
SUBCLAVIAN
GROOVE
PULMONARY
ARTERY
BRONCHUS
PULMONARY
VEINS
BRONCHIAL
ARTERIES
BRONCHIAL
LYMPHATIC
GLAND
LIGAMENTUM
LATUM
PULMONIS
CARDIAC
DEPRESSION
INFERIOR
BORDER
FIG. 1005. — The left lung. The inner or mediastinal surface, with the root of the lung cut across. (Toldt )
projects for some distance into the phrenico-costal sinus of the pleura, between
the lower ribs and the costal attachment of the Diaphragm, extending lower
down externallv and behind than in front
1400
THE ORGANS OF VOICE AND RESPIRATION
Surfaces. The External, Costal, or Thoracic Surface (fades costalis] (Figs. 1008
and 1009). — The external, costal, or thoracic surface is smooth, convex, of con-
siderable extent, and corresponds to the form of the cavity of the chest, being
deeper behind than in front. In a hardened specimen this surface has grooves
and bulgings on it corresponding to the ribs and intercostal spaces.
The Inner or Mediastinal Surface (Jades mediastinalis)(Figs.l6Q4 and 1005). — The
FIG. 1006. — Front view of the heart and lungs.
inner or mediastinal surface is concave. It presents in front a depression corre-
sponding to the convex surface of the pericardium, and behind a deep fissure, the
hilum (hilus pulmonalis). In the hilum lie the bronchi, vessels, nerves, and
lymph-nodes, which together constitute the root of the lung. On the inner and
anterior surface, a little below the apex, is a groove, the subclavian groove (sulcus
subdavius), for the subclavian artery. A little lower is a broader and shallower
groove for the innominate and subclavian veins. The pleura lies between the
lungs and these vessels. . In front of the hilum and below it is a depression for
the heart (impressio cardiaca). It is deeper on the left than on the right side.
On the right side it passes into the groove from the precava and the vena azygos
major. On the left side, behind the hilum, is a groove for the thoracic aorta; on
the right side a groove for the oesophagus.
Borders. The Inferior Border (margo inferior). — The inferior border is the line
of junction of the costal and diaphragmatic surfaces. Posteriorly, it is rounded
and broad, and is received into the deep concavity on either side of the spinal
column. It is much longer than the anterior border, and projects, below, into
the phrenico-costal sinus.
The Anterior Border (margo anterior). — The anterior border is thin and sharp,
overlaps the front of the pericardium, and is projected into the costo-medi-
THE LUNGS
1401
astinal sinus of the pleura. The anterior border of the right lung is almost
vertical ; that of the left presents, below, an angular notch, the incisura cardiaca,
ENTRANCE OF
VENA AZYGOS
BRANCH OF PUL-
MONARY ARTERY
FIG. 1007. — Pulmonary veins, seen in a dorsal view of the heart and lungs. The lungs have been pulled
away from the median line, and a part of the right lung has been cut away to display the air-ducts and blood-
vessels. (Testut.)
FIG. 1008. — The right lung. The outer or costal
surface. (Toldt.)
FIG. 1009. — The left lung. The outer or costal
surface. (Toldt.)
into which the heart and pericardium are received. A projection from the upper
lobe comes forward beneath the cardiac notch; it is called the lingula pulmonis.
The Lobes of the Lungs (Figs. 1008 and 1009).— Each lung is divided into two
lobes, an upper (lobus superior] and a lower (lobus inferior}, by a long and deep
1402 THE ORGANS OF VOICE AND RESPIRATION
fissure (incisura interlobaris), which extends from the upper part of the posterior
border of the organ about three inches from its apex, downward and forward to
the lowest part of the lung just external to its anterior border. This fissure pene-
trates nearly to the root. The upper lobe is the smaller; the lower lobe is the
larger. In the right lung the upper lobe is partially subdivided by a second and
shorter fissure, which extends almost horizontally forward from the middle of
the preceding to the anterior margin of the organ, marking off a small triangular
portion, the middle lobe (lobm medius).
The right lung is the larger and heavier; it is broader than the left, owing to
the inclination of the heart to the left side; it is also shorter by an inch, in conse-
quence of the Diaphragm rising higher on the right side to accommodate the liver.
The Root of the Lung (radix pulmonis) (Figs. 1004,1005, 1006, and 1007).— A
little above the middle of the inner surface of each lung, and nearer its posterior
than its anterior border, is its root, by which the lung is connected to the heart
and the trachea. The root is formed by the bronchial tube, the pulmonary
artery, the pulmonary veins, the bronchial arteries and veins, the pulmonary
plexus of nerves, lymphatics, bronchial glands, and areolar tissue, all of which
are enclosed by a reflection of the pleura. The root of the right lung lies behind
the precava and ascending portion of the aorta, and below the vena azygos major.
The root of the left lung passes beneath the arch of the aorta and in front of the
descending aorta; the phrenic nerve and the anterior pulmonary plexus lie in
front of each, and the vagus and posterior pulmonary plexus behind each.
The chief structures composing the root of each lung are arranged in a similar
manner from before backward on both sides — viz., the two pulmonary veins in front;
the pulmonary artery in the middle; and the bronchus, together with the bronchial
vessels, behind. From above downward, on the two sides, their arrangement differs,
thus: On the right side their position is — bronchus, pulmonary artery, pulmonary
veins; but on the left side their position is — pulmonary artery, bronchus, pulmo-
nary veins. It should be noted that the entire right bronchus, does not lie above
the right pulmonary artery, but only its eparterial branch (see p. 1385), which
passes to the upper lobe of the right lung; the divisions of the bronchus for the
middle and lower lobes lie below the artery.
The true weight of the human lungs as ascertained in the bodies of criminals
executed by electricity, in which the mode of death is attended by a nearly bloodless
condition of the lungs, is 215 grams (7^ ounces) for the left lung and 240 grams
(8£ ounces) for the right lung (E. A. Spitzka, Amer. Jour, of Anat., iii., 1, p. v.).
Ordinarily, with the vascular channels more or less filled with blood and serum,
the two lungs together weigh about 42 ounces, the right lung being 2 ounces
heavier than the left, but much variation is met with according to the amount of
blood or serous fluid they may contain. The lungs are heavier in the male than
in the female. The specific gravity of the lung-tissue varies from 0.345 to 0.746.
The color of the lungs at birth is a pinkish-white; in adult life a dark slate-
color, mottled in patches; and as age advances this mottling assumes a black
color. The coloring matter consists of granules of a carbonaceous substance
deposited in the areolar tissue near the surface of the organ. It increases in
quantity as age advances, and is more abundant in males than in females. The
posterior surface of the lung is usually darker than the anterior.
The surface of the lung is smooth, shining, and marked out into numerous
polyhedral spaces, indicating the lobules of the organ; the area of each of these
spaces is crossed by numerous lighter lines.
The substance of the lung is of a light, porous, spongy texture; it floats in
water and crepitates when handled, owing to the presence of air in the tissue; it
is also highly elastic; hence the collapsed state of these organs when they are
removed from the closed cavity of the thorax.
The Foetal Lung. — After respiration has been established, the lung fills the
pleural cavity. In the foetus, as the lung has never been distended with air
THE LUNGS 1403
and has never received a large amount of blood, it is gathered into a small mass
at the back of the thorax. It will sink in water and feels solid to the touch.
Structure. — The structure of the lung is such that the blood brought by the
pulmonary artery comes into close relation with the air which enters from the
bronchioles. The blood gives materials to the air, and the air gives elements to
the blood, and the process of respiration causes the dark blood brought from the
heart by the pulmonary artery to return to the heart as red blood in the pulmonary
vein. The lungs are composed of an external serous coat, a subserous areolar tissue,
and the pulmonary substance or parenchyma.
The Serous Coat. — The serous coat is thin, transparent, and invests the entire
organ as far as the root. It is known as the pulmonary pleura (p. 1392).
The Subserous Areolar Tissue. — The subserous areolar tissue contains a large
proportion of elastic fibres; it invests the entire surface of the lung, and extends
inward between the lobules, and at the hilum forms the pulmonary scaffold or
framework.
The Parenchyma. — The parenchyma is composed of lobules which, although
closely connected together by an interlobular areolar tissue, are quite distinct from
one another, and may be teased asunder without much difficulty in the fretus.
The lobules vary in size; those on the surface are large, of pyramidal form, with
the bases turned toward the surface; those in the interior are smaller and of various
forms. Each lobule is composed of one of the ramifications of a bronchial tube
and its terminal air-cells, and of the ramifications of the pulmonary and bronchial
vessels, lymphatics, and nerves, all of these structures being connected together by
areolar tissue.
The Bronchus (pp. 1384 and 1386) (Figs. 993, 994, and 995).— The bronchus,
upon entering the substance of the lung, divides and subdivides bipinnately,
throughout the entire organ. Sometimes three branches arise together, and occa-
sionally small lateral branches are given off from the sides of a main trunk. Each
of the smaller subdivisions of the bronchi enters a pulmonary lobule, and is termed
a lobular bronchial tube or bronchiole (bronchioli). Each bronchiole divides into
minute branches (bronchioli respiratorii) , the walls of which now begin to present
irregular dilatations, bronchial alveoli. These are present at first sparingly and on
one side of the tube only, but as it proceeds onward these dilatations become more
numerous and surround the tube on all sides, so that it loses its cylindrical char-
acter. The terminal branches come from the bronchioli respiratorii. These
terminal branches are called the alveolar ducts or alveolar passages (ductuli alveo-
lares). The alveolar ducts show numerous alveoli (Fig. 994) and join with cav-
ities called atria. Each atrium joins several larger cavities, the air-cells or air-sacs
(infundibula) . The numerous small cavities on the surface of the air-sacs are
the pulmonary alveoli (alveoli pidmonis) . The bronchiole now becomes widened
out and terminates in an irregular cul-de-sac, the air cell, air sac alveolus or infun-
dibulum. The walls of the infundibulum are closely beset in all directions by pul-
monary alveoli or pulmonary air cells. Professor Gerrish remarks that the first of
the alveoli seen on the bronchioles before the coreal ends are formed would seem
an effort on the part of nature to form an infundibulum before all the necessary
conditions are favorable.
Changes in the Structure of the Bronchi in the Lungs.— Within the lungs the
bronchial tubes are circular, not flattened (Fig. 995), and present certain pecu-
liarities of structure.
In the Lobes of the Lungs. — In the lobes of the lungs the following changes
take place: The cartilages are not imperfect rings, but consist of thin laminae,
of varied form and size, scattered irregularly along the sides of the tube, being
most distinct at the points of division of the bronchi. They may be traced into
tubes, the diameter of each of which is only one-fourth of a line. Beyond this
point the tubes are wholly membranous. The fibrous coat is continued into the
1404 THE ORGANS OF VOICE AND RESPIRATION
smallest ramifications of the bronchi. The muscular coat is disposed in the form
of a continuous layer of annular fibres, which may be traced upon the smallest
bronchial tubes, and consists of the unstriped variety of muscular tissue. The
mucous membrane lines the bronchi and their ramifications throughout, and is
covered with columnar ciliated epithelium.
In the Lobules of the Lung. — In the lobular bronchial tubes and in the infun-
dibula the following changes take place: The muscular tissue begins to disap-
pear, so that in the infundibula there is scarcely a trace of it. The fibrous coat
becomes thinner, and degenerates into areolar tissue. The epithelium becomes
non-ciliated and flattened. This occurs gradually; thus, in the lobular bronchioles
patches of non-ciliated flattened epithelium may be found scattered among the
columnar ciliated epithelium; then these patches of non-ciliated flattened epithe-
lium become more and more numerous, until in the infundibula and air-cells all
the epithelium is of the non-ciliated pavement variety. In addition to these flat-
tened cells, there are small polygonal granular cells in the air-sacs, in clusters of
two or three, between the others.
The air-cells are small, polyhedral recesses composed of a fibrillated connec-
tive tissue and surrounded by a few involuntary muscular and elastic fibres. Free
in their cavity are to be seen under the microscope granular, rounded, amoeboid
cells (eosinophile leukocytes), often containing carbonaceous particles. The air-
cells are well seen on the surface of the lung, and vary from -%$-$ to T\j- of an
inch in diameter, being largest on the surface at the thin borders and at the apex,
and smallest in the interior.
Mucous Glands. — In the larger bronchi the mucous membrane contains goblet
cells. When the tubes dimmish to 1 mm. in diameter the glands grow fewer.
In the smaller bronchi there are no mucous glands.
Vessels of the Lungs. — The pulmonary artery (Figs. 1006 and 1007) conveys the
venous blood to the lungs; it divides into branches which accompany the bronchial
tubes, and terminates in a dense capillary network upon the walls of the inter-
cellular passages and air-cells. In the lung the branches of the pulmonary artery
are usually above and in front of a bronchial tube, the vein below.
The pulmonary capillaries form plexuses which lie immediately beneath the
mucous membrane in the walls and septa of the air-cells and of the infundibula.
In the septa between the air-cells the capillary network forms a single layer. The
capillaries form a very minute network, the meshes of which are smaller than the
vessels themselves;1 their walls are also exceedingly thin. The arteries of neigh-
boring lobules are independent of each other, but the veins freely anastomose
together.
The pulmonary veins commence in the pulmonary capillaries, the radicles
coalescing into larger branches, which run along through the substance of the
lung, independently from the minute arteries and bronchi. After freely commu-
nicating with other branches they form large vessels, which ultimately come into
relation with the arteries and bronchial tubes, and accompany them to the hilum
of the organ. Finally they open into the left auricle of the heart, conveying
oxygenated blood to be eventually distributed to all parts of the body by the aorta.
The bronchial arteries supply blood for the nutrition of the lung. The thoracic
aorta usually gives off two left bronchial arteries. The single right bronchial
artery usually arises from the first right aortic intercostal, but sometimes from
the superior left bronchial artery, or from the aorta. In the root of the lung
they are posterior to the bronchus, they accompany the bronchial tubes, supply
the tubes and pulmonary tissue, and give branches to the walls of the larger
pulmonary vessels, the oesophagus, pericardium, and bronchial glands. Those
1 The meshes are only 0.002'" to 0.008'" in width, while the vessels are 0.003'" to 0.005'" (Kolliker, Human
Microscopic Anatomy). — ED. of 15th English edition.
THE LUNGS 1405
supplying the bronchial tubes form a capillary plexus in the muscular coat, from
which branches are given off to form a second plexus in the mucous coat. This
plexus communicates with branches of the pulmonary artery, and empties itself
into the pulmonary vein. Others are distributed in the interlobular areolar tissue,
and terminate partly in the deep, partly in the superficial, bronchial veins. Lastly,
some ramify upon the surface of the lung beneath the pleura, where they form a
capillary network. There may be but one bronchial artery; there may be three
or four.
The bronchial veins are not found in the walls of the very small bronchi. The
small bronchial veins run along by the front and back of the median sized and
larger tubes, and from two trunks at the root of each lung. These vessels termi-
nate on the right side in the vena azygos major, and on the left side in the superior
intercostal or left upper azygos vein. Tracheal and posterior mediastinal veins
open into the bronchial veins. The venous blood from the smaller tubes passes
to the pulmonary veins.
The lymphatics begin in networks about the lobules and form networks about
the bronchi and beneath the bronchial mucous membrane. The superficial col-
lecting trunks arise about the lobules and beneath the pleura. According to
Sappey, the superficial trunks from the upper lobe begin on the costal surface;
one set passes around the anterior border, another set around the posterior
border, and a third into the incisura interlobaris. The same observer says that the
superficial trunks from the middle lobe unites with the trunks from the upper and
lower lobes; and the superficial trunks from the lower lobe, like those of the upper
lobe, are in three sets. One set passes around the posterior margin, one around the
anterior margin, and one into the incisura interlobaris. All of the superficial trunks
convey lymph to the glands of the hilum. Some of the deep collecting trunks begin
by the sides of the small bronchi; others course along by the pulmonary veins
or pulmonary arteries. All of them pass to the glands of the hilum. The glands
of the hilum are in communication with the peritracheo-bronchial glands.1
Nerves. — The lungs are supplied from the anterior and posterior pulmonary
plexuses, formed chiefly by branches from the sympathetic and vagus. The fila-
ments from these plexuses accompany the bronchial tubes, and are lost upon them.
Small ganglia are found upon these nerves.
Surface Form. — The apex of the lung is situated in the neck, behind the interval between the
two heads of origin of the Sterno-mastoid muscle. The height to which it rises above the clavicle
varies very considerably, but is generally about one inch. It may, however, extend as much as
an inch and a half or an inch and three-quarters, or, on the other hand, it may scarcely project
above the level of this bone. In order to mark out the anterior margin of the lung, a line is
to be drawn from the apex-point, one inch above the level of the clavicle, and rather nearer the
posterior than the anterior border of the Sterno-mastoid muscle, downward and inward across
the sterno-clavicular articulation and first piece of the sternum until it meets, or almost meets,
its fellow of the other side opposite the articulation of the manubrium and gladiolus. From this
point the two lines are to be drawn downward, one on either side of the mesial line and close to
it, as far as the level of the articulation of the fourth costal cartilages to the sternum. From
here the two lines diverge; the left is to be drawn at first passing outward with a slight inclina-
tion downward, and then taking a bend downward with a slight inclination outward to the apex
of the heart, and thence to the sixth costo-chondral articulation. The direction of the anterior
border of this part of the left lung is denoted with sufficient accuracy by a curved line with its
convexity directed upward and outward from the articulation of the fourth right costal cartilage
of the sternum to the fifth intercostal space, an inch and a half below and three-quarters of an
inch internal to the left nipple. The continuation of the anterior border of the right lung is
marked by a prolongation of its line from the level of the fourth costal cartilages vertically
downward as far as the sixth, when it slopes off along the line of the sixth costal cartilage to its
articulation with the rib.
The lower border of the lung is marked out by a slightly curved line with its convexity down-
ward from the articulation of the sixth costal cartilage to its rib to the spinous process of the
tenth thoracic vertebra. If vertical lines are drawn downward from the nipple, the mid-axillary
line, and the apex of the scapula, while the arms are raised from the sides, they should intersect
1 The Lymphatics, by Poirier, Cunt5o, and Delamare. Translated and edited by Cecil H. Leaf.
1406 THE ORGANS OF VOICE AND RESPIRATION
this convex line, the first at the sixth, the second at the eighth, and the third at the tenth rib.
It will thus be seen that the pleura extends farther down than the lung, so that it may be
wounded, and a wound may pass through its cavity into the Diaphragm, and the abdominal
viscera may be injured without the lung being involved.
The posterior border of the lung is indicated by a line drawn from the level of the spinous
process of the seventh cervical vertebra, down either side of the spine, corresponding to the
costo-vertebral joints as low as the spinous process of the tenth thoracic vertebra. The trachea
bifurcates opposite the spinous process of the fourth thoracic vertebra, and from this point the two
bronchi are directed outward.
"The position of the great fissure of the lungs may be indicated by a line drawn from the third
dorsal spine obliquely downward in such a manner as to reach the sixth rib close to the mid-
clavicular line. The interlobar fissure between the upper and middle lobes of the right lung
corresponds to a line drawn from the apex of the axilla almost horizontally to the sternum,
reaching the latter at about the level of the fourth costal cartilage" (Erendrath).
Surgical Anatomy. — The lungs may be wounded or torn in three ways: (1) By compres-
sion of the chest, without any injury to the ribs. (2) By a fractured rib penetrating the lung.
(3) By stabs, gunshot wounds, etc.
The first form, where the lung is ruptured by external compression without any fracture of
the ribs, is very rare, and usually occurs in young children, and affects the root of the lung —
i. e., the most fixed part — and thus, implicating the great vessels, is frequently fatal. It would
seem to be a most unusual injury, and the exact mode of its causation is difficult to understand.
The probable explanation is that immediately before the compression is applied a deep inspira-
tion is taken and the lungs are fully inflated; owing then to spasm of the glottis at the moment
of compression, the air is unable to escape from the lung, the lung is not able to recede, and
consequently gives way.
In the second variety, when the wound in the lung is produced by the penetration of a broken
rib, both the pleura costalis and the pleura pulmonalis must necessarily be injured, and conse-
quently the air taken into the wounded air-cells may find its way through these wounds into the
cellular tissue of the parietes of the chest. This it may do without collecting in the pleural cavity;
the two layers of the pleura are so intimately in contact that the air may pass straight through
from the wounded lung into the subcutaneous tissue. Emphysema constitutes, therefore, an
important sign of injury to the lung in cases of fracture of the ribs. Pneumothorax , or air in the
pleural cavity, is much more likely to occur in injuries to the lung of the third variety; that is
to say, from external wounds, from stabs and gunshot injuries, in which cases air passes either
from the wound of the lung or from an external wound into the cavity of the pleura dur-
ing the respiratory movements. In these cases there is generally no emphysema of the sub-
cutaneous tissue unless the external wound is small and valvular, so that the air drawn into the
wound during inspiration is then forced into the cellular tissue around during expiration because
it cannot escape from the external wound. Occasionally in wounds of the parietes of the chest
no air finds its way into the cavity of the pleura, because the lung at the time of the accident
protrudes through the wound and blocks the opening. This occurs where the wound is large,
and constitutes a so-called hernia of the lung. True hernia of the lung occurs, though very
rarely, after wounds of the chest-wall, when the wound has healed and the cicatrix sub-
sequently yields from the pressure of the viscus behind. It forms a globular, elastic, crepi-
tating swelling, which enlarges during expiratory efforts, falls during inspiration, and disappears
on holding the breath. Wounds of the lung may produce dangerous or fatal hemorrhage into
the pleural sac. In many cases the bleeding is spontaneously arrested; in diners the surgeon
must interfere to save life. In some cases air has been admitted by intercostal incision and the
insertion of a tube, and pulmonary collapse has arrested bleeding. In other cases it is necessary
to resect portions of several ribs, and stop bleeding by ligatures or suture ligatures. In one
case of a furious secondary hemorrhage following a gunshot wound, the editor resected several
ribs, packed the pleural cavity about the lung with sterile gauze, to obtain a base of support, and
then arrested the bleeding by packing iodoform gauze against the firmly supported lung. This
patient recovered.
Incision of the lung (pneumotomy) is performed for pulmonary abscess (either tuberculous or
pyogenic), pulmonary gangrene, hydatid cysts, and bronchiectasis. In pulmonary abscess,
locate the area by physical signs and the axray, resect a portion of a rib over it, and note if the
pleura is adherent. If it is adherent, continue the operation. If it is not adherent, insert stitches
of catgut through the two layers of pleura and the superficial part of the lung, so as to encircle
a considerable area, and then wait several days for adhesions to form. Adhesions protect the
pleura from infection, and, by keeping air from the pleural sac, prevent pneumothorax. When
ready to continue the operation, locate the abscess with an aspira ting-needle and syringe, open
it with a cautery at a dull-red heat, and drain by means of a tube.
Pneumotomy is very unsatisfactory in tuberculous cavities and bronchiectasis. In tubercu-
losis, excision of the diseased area (pneumectomy) has been employed, but it is not to be advised.
Operations upon the lungs can be most safely performed with the patient in a Sauerbruch
chamber. The danger of collapse of the lung is thus eliminated.
THE DUCTLESS GLANDS.
fTIHESE glands do not possess excretory ducts. They furnish materials which
-L are added to the blood or lymph as it passes through them. The material
from each gland is known as an internal secretion. Some of these secretions are
powerful materials and influence profoundly the body nutrition. The ductless
glands are usually given as follows: the spleen, the lymphatic glands, the pineal
gland, the pituitary body, the suprarenal capsules, the thyroid gland, the para-thyroids,
the thymus, the carotid body, and the coccygeal body. The lymphatic glands were
described in a special section (p. 772). The lymphatic glands are not con-
sidered to be really glands, but, nevertheless, as lymph passes through the lymph
glands, it receives a product of the glands, namely, lymphocytes. There is no
evidence that the spleen furnishes an active internal secretion, and this organ
has been studied with the abdominal viscera. The pineal gland (p. 915) and
pituitary body or hypophysis (p. 917) were considered with, the brain. The supra-
renal capsules (p. 1437) are described with the kidneys. Some glands, for instance,
the liver, pancreas, and testicle, have an external secretion and also an internal
secretion.
THE THYROID BODY OR GLAND (GLANDULA THYREOIDEA)
(Fig. 1010).
The thyroid gland is an extremely vascular body, situated at the front and
sides of the neck, and extending upward upon each side of the larynx. It is a
single gland, varying greatly in size in different individuals. It is larger relatively
in females and in children than in men. It is frequently asymmetrical. In early
embryonal life the gland has a duct, the thyro-glossal duct (ductus thyreoglossus) ,
which passes from the isthmus of the thyroid to the foramen caecum of the dorsum
of the tongue. The lumen of this duct is obliterated early and becomes a cord of
epithelium. The lower portion of the duct often remains open for a little way.
The upper portion remains as the foramen caecum. The situation of this obliter-
ated foetal duct may be marked by the third or middle lobe of the thyroid gland.
The thyroid surrounds the upper portion of the trachea like a horseshoe. It con-
sists of two lateral lobes connected across the middle line by a narrow transverse
portion, the isthmus.
The weight of the gland is somewhat variable, but is usually about one ounce.
It is somewhat heavier in the female, in whom it becomes enlarged during men-
struation and pregnancy. As age advances the weight of the thyroid diminishes.
The color of the thyroid, as seen from the surface, is reddish-blue. The gland is
completely surrounded by a closely adherent thin fibrous-tissue capsule of the pre-
tracheal layer of deep cervical fascia. From the inner surface of the capsule come
delicate septa, which enter into the thyroid body and separate it into lobes and also
separate the lobes into lobules. The blood-vessels lie beneath the capsule. The
anterior and lateral portions of the gland are covered by the capsule. "Passing
around the side of the gland to its posterior surface, this capsule then splits into two
portions. One remains in contact with the gland and invests its posterior surface.
The other, the thicker of the two, passes to the posterior surface of the pharynx
( 1407 )
1408
THE DUCTLESS GLANDS
and oesophagus, thus enclosing them with the larynx, trachea, and thyroid gland,
in a common sheath."1 There is also a layer from the thyroid capsule which
passes between the trachea and oesophagus.2
The lateral lobes are conical in shape, the apex of each being directed upward
and outward as far as the junction of the middle with the lower third of the thy-
roid cartilage; the base looks downward, and is on a level with the fifth or sixth
tracheal ring. The summit of the lateral lobe not unusually is pointed and reaches
to the level of the oblique line upon the ala of the thyroid cartilage or even higher.
The right is, as a rule, somewhat larger than the left lobe. The lower portion of
the gland, when the head is extended, is about
one inch above the upper margin of the ster-
num; when the head is flexed, it is at the level
of the upper border of the sternum or even
below and behind it. The portion of the
lateral lobe above the level of the superior
border of the isthmus is called the upper horn,
the portion below the level of the inferior mar-
gin of the isthmus is called the lower horn. The
lower horn "is usually much smaller than the
upper horn ; frequently it is altogether absent."3
At the inner and posterior part of each lateral
lobe is the hilum. At the hilum the inferior
thyroid artery passes into the gland. "Here
the recurrent laryngeal nerve comes into close
contact with the gland, lying in the space be-
tween it and the trachea and oesophagus."4
The external or superficial surface is convex,
and covered by the skin, the superficial fascia,
the deep fascia, the Sterno-mastoid, the anterior
belly of the Omo-hyoid, the Sterno-hyoid and
Sterno-thyroid muscles, and beneath the last-
named muscles by the pre-tracheal layer of the
deep fascia, which forms a capsule for the
gland.
The deep or internal surface is moulded
over the underlying structures — viz., the thy-
roid and cricoid cartilages, the trachea, the
inferior constrictor and posterior part of the
Crico-thyroid muscles, the oesophagus (par-
ticularly on the left side of the neck), the supe-
rior and inferior thyroid arteries, and the recurrent laryngeal nerves.
The deep surface of each lobe is fixed by bands of fibrous tissue passing from
the capsule of the isthmus and lateral lobes to the sides of the cricoid cartilage and
the posterior fascia of the trachea. These bands are called the lateral or suspen-
sory ligaments. Because of this fixation to the larynx and trachea by the capsule
and by the lateral ligaments, the thyroid gland moves with the trachea and ascends
during the act of swallowing. The recurrent laryngeal nerve on each side is in
contact with the outer and posterior surface of the suspensory ligament.
The anterior border is thin, and inclines obliquely from above downward and
inward toward the middle line of the neck, while the posterior border is thick and
overlaps the common carotid artery. Each lobe is about two inches in length, its
greatest width is about one inch and a quarter, and its thickness about three-
FIG. 1010.— The thyroid gland. (Spalteholz.)
1 Diseases of the Thyroid Gland. By James Berry.
- C. H. Mayo, Surgery, Gynecology, and Obstetrics, July, 1907.
3 Loc. cit.
< Ibid.
THE THYROID BODY OR GLAND 1409
quarters of an inch. The posterior border is over the common carotid artery and
touches the oesophagus and pharynx. The carotid artery usually makes a groove
upon the gland.
The Isthmus (isthmus glandulae thyreoidea}. — The isthmus connects the lower
third of the two lateral lobes; it measures about half an inch in breadth and the
same in depth, and usually covers the second and third rings of the trachea, but
sometimes also the first and fourth rings. Its situation presents, however, many
variations, a point of importance in the operation of tracheotomy. In the middle
line of the neck it is covered by the skin and fascia, and close to the middle line,
on either side, by the Sterno-hyoid muscle. Across its upper border run branches
of the superior thyroid artery and vein; at its lower border is a branch of the
inferior thyroid veins. Sometimes the isthmus is altogether wanting, the two
lateral lobes being completely separate.
The third, pyramidal or middle lobe is called the pyramid of Lalouette. It is not
constant, but is frequently found. Occasionally it arises from the upper part of
the isthmus, or from the adjacent portion of either lobe, but most commonly from
the left lobe, and ascends in front of the thyroid cartilage in the direction of the
middle of the hyoid bone. It may reach the bone or may not reach it. If it
reaches the bone it is attached to it. If it does not reach the bone, fibrous tissue,
which often contains muscle, is prolonged from the tip of the pyramid to the
back of the bone or to the thyro-hyoid membrane. The pyramid is occasionally
quite detached, or divided into two or more parts, or altogether wanting,
A few muscular bands, derived from the Thyro-hyoid muscles, are occasionally
found attached, above, to the body of the hyoid bone, and below to the isthmus
of the gland or its pyramidal process. These form a muscle, which was named
by Soemmerring the Levator glandulae thyreoidae.
Accessory Thyroids (glandulae thyreoideae accessoriae) . — Frequently small
isolated masses of thyroid tissue exist. They are found particularly about the
lateral lobes of the thyroid gland in the sides of the neck or just above the hyoid
bone, and are called accessory thyroids. Accessory thyroids may also exist by the
side of the pyramidal lobe or upon the trachea, as low even as the level of the arch
of the aorta. John B. Murphy1 says, the field in which accessory thyroids "may
be found can be roughly represented by an inverted trapezoid, the larger base
being a line running from one apex of the mastoid process to the other; the smaller
base is a line tangential to the arch of the aorta, and the sides are the two sterno-
mastoid muscles." These isolated portions of gland tissue represent isolated por-
tions of the median thyroid rudiment. Sometimes accessory thyroid tissue is found
in the root of the tongue or in the interior of the larynx. Berry points out that a
distinction must be made between true congenital accessory thyroids and masses
of encapsuled thyroid tissue which "have been extruded from the gland," and still
retain a connection with the gland. Such masses are false accessory thyroids.
Structure of the Thyroid (Fig. 1011). — The thyroid body is invested by a thin
capsule of connective tissue which projects into its substance as a framework and
imperfectly divides it into masses of irregular form and size, known as lobules.
More slender septa separate the secretory alveoli from one another. When the
organ is cut into, it is of a brownish-red color, and is seen to be made up of a
number of closed vesicles or alveoli containing a yellow glairy fluid and separated
from each other by intermediate connective tissue.
According to Baber, who has published some important observations on the
minute structure of the thyroid,2 the vesicles of the thyroid of the adult animal
are generally closed cavities; but in some young animals (e.g., young dogs) the
vesicles are more or less tubular and branched. This appearance he supposes
1 Journal of the American Medical Association, December 16, 1905.
* Researches on the Minute Structure of the Thyroid Glands, Phil. Trans., part Hi., 1881.
89
1410
THE DUCTLESS GLANDS
to be due to the mode of growth of the gland, and merely indicating that an
increase in the number of vesicles is taking place. Each vesicle is lined by a single
layer of epithelium, the cells of which are cubical or cylindrical. Between the
epithelial cells exists a delicate reticulum. The vesicles are of various sizes and
shapes, and contain as a normal product a viscid, homogeneous, semi-fluid,
slightly yellowish material which frequently contains blood, the red corpuscles of
which are found in it in various stages of disintegration and decolorization, the
yellow tinge being probably due to the haemoglobin, which is thus set free from
the colored corpuscles. This normal product is known as colloid material, and it
is secreted by the epithelium. What part if any the colloid plays in the formation
of the internal secretion of the gland is not known. It is quite possible that the
colloid corresponds to the external secretion of glands with ducts and that the
true internal secretion passes directly into the capillaries which form a network
about the alveoli (Szymonowicz), or passes into the lymphatics. In the thyroid
gland of the dog, Baber has found large round cells, parenchymatous cells, each
provided with a single oval-shaped nucleus, which migrate into the interior
of the gland-vesicles. Between the thyroid vesicles in the human being are col-
lections of round cells. They are, in reality, miniature vesicles, and are much
more numerous in youth than in old age.
The capillary blood-vessels form a dense plexus in the connective tissue around
the vesicles, between the epithelium of the vesicles and the endothelium of the
lymph -spaces, which latter surround a greater or smaller part of the circumference
Vesicle.
Lymphatic vessel,
Wall of gland-vesicle
FIG. 1011. — Minute structure of the thyroid. From a transverse section of the thyroid of a dog. Semi-
diagrammatic. (Baber.)
of the vesicles. These lymph-spaces empty themselves into lymphatic vessels
which run in the interlobular connective tissue, not uncommonly surrounding the
arteries which they accompany, and communicate with a network in the capsule
of the gland. Small glands may be connected with this network. Baber has
found in the lymphatics of the thyroid a viscid material which is morphologically
identical with the normal constituent of the vesicle.
Vessels and Nerves. — The arteries (Figs. 394 and 395; see also p. 604) supply-
ing the thyroid are the superior thyroid from the external carotid, and the inferior
thyroid from the thyroid axis of the first part of the subclavian. Sometimes there
is an additional vessel, the thyroidea media or ima, usually arising from the
THE THYROID BODY OR GLAND 1411
innominate artery, but sometimes from the arch of the aorta or the common caro-
tid. It ascends upon the front of the trachea. The superior thyroid artery reaches
the summit of the upper horn of the gland, and usually at this point gives off a
vessel which courses down the posterior surface of the gland. The main trunk
passes downward and inward at the junction of the inner and anterior border of
the upper horn, giving branches to adjacent structures and sending branches over
the anterior surface of the thyroid gland. It reaches the isthmus and crosses
the isthmus at its upper border to anastomose with the artery from the other side.
The inferior thyroid artery, which is usually larger than the superior, after it
has passed posterior to the sheath of the carotid and the sympathetic nerve, reaches
the posterior surface of the gland. At this point branches are given off; some pass
into the hilum; the others go to the posterior surface of the gland. The relation
of the artery to the recurrent laryngeal nerve is very important to the surgeon.
"Usually the main trunk of the artery passes behind the nerve; sometimes the
artery breaks up before reaching the nerve ; in this case one or more of the branches
may pass in front of it. Much less commonly the main trunk or all its branches
will be found to lie in front of the nerve."1 If the thyroidea ima is present it goes
to the lower part of the gland. The larger branches of the thyroid arteries are
beneath the capsule and upon the surface of the gland ; smaller branches pass to
the interior of the gland (Berry). The arteries are remarkable for their large
size and frequent anastomoses.
The thyroid veins (Figs. 447 and 448; see also p. 731) form a plexus upon the
surface of the gland and beneath the capsule. Here and there veins pass through
the capsule and go to adjacent venous trunks. Berry, accepting Kocher's descrip-
tion, notes the following veins: The superior thyroid vein runs with the superior
thyroid artery and passes to the internal jugular vein. A transverse vein of the
upper border of the isthmus joins the two superior thyroid veins. A single vein,
the middle thyroid, sometimes emerges from the side of the gland and passes to
the internal jugular. Usually, however, instead of this single vein there are two
veins, the superior and inferior accessory thyroids. The superior accessory thyroid
emerges from the outer side of the upper horn, below the apex, and passes to the
internal jugular. The inferior accessory thyroid emerges from the posterior and
inferior portion of the gland and passes to the internal jugular. The veins from the
lower border of the gland vary greatly. A vein passes vertically down on each side
in front of the trachea from the isthmus and from the inner side of tho, inferior horn.
It is called by Kocher the thyroidea ima. The vein of the left side passes to the left
innominate; the vein of the right side passes to the right innominate or left innom-
inate. As Berry points out, the vein of one side may be small or may be absent,
or the two veins may unite and form one vein which enters the left innominate.
An inferior thyroid vein is often present. It is of small size, emerges at the inferior
and external part of the gland, and passes to the corresponding innominate vein,2
The lymphatics are numerous and of large size. Collecting trunks arise from a
network within the capsule. Some trunks ascend from the upper margin of the
isthmus and reach the gland in front of the larynx ; others ascend along the superior
thyroid artery and reach the glands at the bifurcation of the carotid. Descending
trunks from the lower margin of the isthmus reach the glands in front of the
trachea; trunks from the side of the gland descend to the glands about the recur-
rent laryngeal nerve.3
The nerves are derived from the middle and inferior cervical ganglia of the sym-
pathetic, and from the inferior laryngeal nerves. Probably there is also a branch
from each superior laryngeal nerve.
Surgical Anatomy. — The thyroid gland may be congenitally absent, and when it is the indi-
vidual suffers from the worst form of cretinism. One lobe may be congenitally absent, but
this will provoke no trouble unless the other lobe undergoes atrophy.
1 Diseases of the Thyroid Gland. By James Berry. 2 Ibid.
8 The Lymphatics. By Poirier, Cuneo, and Delamare, Translated and edited by Cecil H. Leaf.
1412
THE DUCTLESS GLANDS
Complete removal of the thyroid and parathyroids will produce operative myxoedema (cachexia
strumipriva), unless accessory thyroids enlarge and perform the functions of the thyroid.
The thyroid gland may be congenitally enlarged. The gland tends to atrophy in old age.
It is atrophied in myxoedema and cretinisin. Some forms of thyroid enlargement are called
goitre.
When all parts of the gland enlarge the condition is known as parenchymatous goitre.
Adenomatous goitre consists of an adenoma or of adenomata. In cystic goitre there is one
or more cysts due to cystic degeneration of adenomata or to fusion of adjacent follicles.
A pulsating goitre is one which receives impulses from the carotid pulsations. In a fibroid
goitre there is increase of interstitial connective tissue. A goitre which passes back of the sternum
is known as substernal or intrathoracic. A goitre may extend back of the trachea or back of
the oesophagus.
Exophthalmic goitre, Graves's disease or Basedow's disease, is a remarkable disease. Its three
chief symptoms are enlargement of the thyroid, or goitre ; prominence of the eyeballs, or exoph-
thalmos, and very rapid pulse, or tachycardia. Dyspnoea, tremor, and various other symptoms
are usually found. The thyroid gland may be the seat of a carcinoma or sarcoma (malignant
goitre}, syphilitic or tuberculous disease, ordinary inflammation, suppuration, or hydatid disease;
For the relief of ordinary goitre various methods have been employed. Tapping, injection of
astringents, simple incision, and the seton are obsolete. Ligature of the thyroid arteries is rarely
performed as a curative measure. The superior and inferior thyroids of one side have been tied
in some cases; all four thyroids in other cases. Jaboulay has performed exothyropexy. In this
operation the gland is dislocated from its bed, brought out of the wound, and left exposed, in
hope that it will atrophy
Division of the isthmus is occasionally practised to relieve dyspnoea. The operation some-
times succeeds, but often fails.
Extirpation of one-half or two-thirds of the gland is a very successful operation. Removal of
the entire gland will be followed by operative myxoedema.
Removal or injury of the parathyroids causes tetany.
In extirpating a lobe of the thyroid by the method until
recently in vogue, great care must be taken to avoid tearing
the capsules, as if this happens the gland-tissue bleeds
profusely. The thyroid arteries should be ligatured on the
diseased side before an attempt is made to remove the
mass, and in ligaturing the inferior thyroid the position of
the recurrent laryngeal nerve must be borne in mind, so as
not to include it in the ligature. In order to preserve the
parathyroids from injury, C. H. Mayo recommends that
after the vessels entering and leaving the thyroid have been
double clamped and divided, the entire lobe should be
elevated, the capsule split along the side of the gland and
pushed back with gauze, and the gland lifted and removed
without disturbing the posterior portion of the capsule l
A cystic or solid tumor of the thyroid may be removed
by intraglandular enucleation. If operation becomes ne-
cessary in exophthalmic goitre, partial extirpation is usu-
ally preferred. Bilateral extirpation of the cervical ganglia
of the sympathetic (sympathectomy or Jonnesco's operation)
has been practised by some surgeons for exophthalmic
goitre. The value of the procedure is uncertain.
THE PARATHYROID GLANDS2 (Fig. 1012).
FIG. 1012. — The position of the para-
thyroid glands. View from behind.
(Zuckerkandl.)
The parathyroid glands or the epithelial cor-
puscles of Kohn were first described as anatomical
entities by Sandstrom in 1880. Owen had seen
the parathyroids in the rhinoceros in 1862, but he did not recognize any peculiarities
of structure. Virchow observed them in man in 1863 but he regarded them as lymph-
glands or detached portions of thyroid tissue. Gley, in 1891, called attention to
glands within the body of the thyroid. In 1895 Kohn affirmed that the parathyroids
are separate organs and not a part of the thyroid gland. If the thyroid gland has
been carefully detached, two round bodies of stnall size may be found embedded
' C. H. Mayo, Surgery, Gyneeology, and Obstetrics, July, 1907.
2 I am indebted to Dr. F. D. Patterson for collecting the literature upon the parathyroids.
THE PARATHYROID GLANDS 1413
upon the trachea or upon the surface of the lateral lobe of the gland, between
the. terminal branches of the inferior thyroid artery. "These are the parathy-
roids, about the size of orange-seeds, and brownish-red in color."1 They are
smaller in infants than in adults. Welsh2 describes them in adults as from
6 to 7 mm. in length, 3 to 4 mm. in breadth, and 1^ to 2 mm. in thickness.
These masses are constant in man. There is no record of a case in which they
were congenitally absent. Although the parathyroids lie on or in the thyroid,
they are always completely separated from it by capsules of connective tissue.
Although there are usually four parathyroids, there may be but three, or there may
be six or even eight. Parathyroid tissue may exist within the thyroid gland even
when the superior parathyroids are present.3 Accessory parathyroids may be found
over a wide area. Rogers and Fergusson found one in the middle of the posterior
portion of the pharynx. Ogle found a gland in the thorax which was partly para-
thyroid. The parathyroids are divided from their situation into external and
internal. The former, usually two in number, are situated, one on each side, in
relation to the postero-internal surface of the lateral lobe of the thyroid; sometimes
they are duplicated. The latter, also usually two in number, are placed one in or
on each lateral lobe of the thyroid, generally near its mesal surface.
Structure. — The structureof thepara thyroids is different from that of the thyroid.
They are composed of solid masses of epithelial cells arranged in a more or less
columnar fashion with numerous intervening capillaries. The columns of the para-*
thyroids anastomose. There is a certain type of cell, but the form varies. These
variations result from changes due to episodes of rest and activity (Verebely).
MacCallum's studies seem to lead to the same conclusion. Thompson4 states that
he finds only one type of cell in the infant gland, and that in the adult there is
primarily but one type of cell, the other cells noted being modifications of the
principal cell due to degeneration or hyp erf unction. There is much lymphoid
tissue connected with the columns. The nerves of the parathyroids are derived
from the sympathetic system. Each parathyroid gland is supplied by a para-
thyroid artery. The inferior parathyroid artery is always a branch of the inferior
thyroid artery or of the anastomosing channel between the superior and inferior
thyroid arteries of one side (Geist). The superior parathyroid artery may be a
branch of the superior thyroid (Poole), but it is usually a branch of the inferior
thyroid or of the anastomosing channel. Ginsburg5 has shown that each of the
glands has an accessory blood supply by anastomotic channels from the opposite
side.
Embryology. — The parathyroids develop chronologically in advance of the
thyroid. They are derived from the third and fourth branchial clefts of each side.
An independent accessory parathyroid may develop from the fifth cleft (Getzowa,
Michand). Some have regarded the parathyroids as embryonic portions of the
thyroid, but, as MacCallum says, " there is no histological proof that parathyroid
tissue can ever become converted into thyroid tissue." Most observers regard the
parathyroids as distinct glands possessed of a special function. Certain it is, as
Gley and others have shown, removal of the parathyroids from herbivora leaving
the thyroid intact is followed by spasms, tetany, etc., just as complete thyroidec-
tomy is followed by such symptoms in carnivora.8
Surgical Anatomy. — Surgeons have become convinced that removal of the parathyroids in man
causes tetany, and that damage to them may produce serious symptoms. Because of this dan-
ger most surgeons now prefer to remove a goitre from within the capsule of the thyroid gland
after the plan of the Mayos, and thus avoiding the parathyroids.
i Practical Anatomy. By Prof. Alfred W. Hughes. * Journal of Anatomy and Physiology, 1897-1898.
3 Getzowa, Virchow's Arch., 1907, clxxxvii., p. 181.
'* American Journal of Medical Sciences, 1907, n. s., cxxxiv., p. 562.
6 University of Pennsylvania Medical Bulletin, January, 1908.
• Internal Secretions. By William Hanria Thomson. New York Medical Journal, November 19, 1904.
1414
THE DUCTLESS GLANDS
THE THYMUS GLAND (Fig. 1013).
The thymus gland is a temporary organ, attaining its full size at the end of the
second year, when it ceases to grow and remains practically stationary until
puberty, at which period it rapidly degenerates. It does not entirely disappear,
for the shrunken and -degenerated mass, even later in life, maintains a likeness to
the original form and retains within its substance small portions of thymus tissue
(Waldeyer). If examined when its growth is most active, it will be found to con-
VAGUS
NERVE
FIG. 1013. —The thymus gland in an infant two months old. (Poiricr and Charpy.)
sist of two lateral lobes placed in close contact along the middle line, situated
partly in the superior mediastinum, partly in the neck, and extending from the
level of the fourth costal cartilage upward as high as the lower border of the
thyroid gland. It is covered by the sternum and by the origins of the Sterno-
hyoid and Sterno-thyroid muscles. Below, it rests upon the pericardium, being
separated from the arch of the aorta and great vessels by a layer of fascia. In the
neck it lies on the front and sides of the trachea, behind the Sterno-hyoid and
Sterno-thyroid muscles. The two lobes generally differ in size; they are occa-
sionally united so as to form a single mass, and are sometimes separated by an
intermediate lobe. The thymus is of a pinkish-gray color, is soft and is lobu-
lated on its surfaces. It is about two inches in length, one and a half inches
in breadth below, and about three or four lines in thickness. At birth it weighs
about half an ounce.
Structure (Figs. 1014 and 1015). — Each lateral lobe is composed of numerous
lobules held together by delicate areolar tissue, the entire gland being enclosed in
an investing capsule of a similar but denser structure. The primary lobules vary
in size from a pin's head to a small pea, and are made up of a number of small
nodules or follicles which are irregular in shape and are more or less fused
together, especially toward the interior of the gland. Each follicle consists of a
THE THYMUS GLAND
1415
medullary and cortical portion, which differ in many essential particulars from
each other. The cortical portion is mainly composed of lymphoid cells sup-
ported by a delicate reticulum. In addition to this reticulum, of which traces
only are found in the medullary portion, there is also a network of finely
branched cells which is continuous with a similar network in the medullary por-
tion. This network forms an adventitia to the blood-vessels. In the medullary
portion there are but few lymphoid cells, but there are, especially toward the
centre, granular cells and concentric corpuscles. The granular cells are rounded
or flask-shaped masses attached (often by fibrillated extremities) to blood-vessels
and to newly formed connective tissue. The concentric corpuscles are com-
posed of a central mass consisting of one or more granular cells, and of a capsule
which is formed of epithelioid cells which are continuous with the branched cells
forming the network mentioned above.
Each follicle is surrounded by a capillary plexus from which vessels pass into
the interior and radiate from the periphery toward the centre, and form a second
zone just within the margin of the medullary portion. In the centre of the
medulla there are very few vessels, and they are of minute size.
FIG. 1014. — Minute structure of thymus gland. Upper portion of the thymus of a foetal pig Of 2" in length,
showing the bud-like lobuli and glandular elements: 2, cells of the thymus, mostly from a man; a, free nuclei;
b, small cells; c, larger; d, larger, with oil-globules, from the ox; e, f, cells completely filled with fat, at /
without a nucleus; g, h, concentric bodies; g, an encapsulated nucleated cell; h, a composite structure of a
similar nature.
Watney has made the important observation that haemoglobin is found in the
thymus either in cysts or in cells situated near to or forming part of the con-
centric corpuscles. This haemoglobin varies from granules to masses exactly
resembling colored blood-corpuscles, oval in the bird, reptile, and fish; circular
in all mammals except in the camel. Dr. Watney has also discovered in the
lymph issuing from the thymus similar cells to those found in the gland, and,
like them, containing haemoglobin either in the form of granules or masses.
From these facts he arrives at the physiological conclusion that the thymus is
one source of the colored blood -corpuscles.
Vessels and Nerves. — The arteries supplying the thymus are derived from
the internal mammary and from the superior and inferior thyroid. The veins
terminate in the two innominate veins, and in the internal mammary and the
thyroid veins. The lymphatics are of large size, arise in the substance of the
gland, and are said to terminate in the internal jugular vein. The nerves are
1410
THE DUCTLESS GLANDS
exceedingly minute; they are derived from the vagus and sympathetic. Branches
from the descendens hypoglossi and phrenic reach the investing capsule, but do not
penetrate into the substance of the gland.
Artery.
Vein.
Artery.
FIG. 1015. — Minute structure of the thymus gland. Follicle of injected thymus from a calf, four days old,
slightly diagrammatic, magnified about 50 diameters. The large vessels are disposed in two rings, one of which
surrounds the follicle, the other lies just within the margin of the medulla. A and B, from thymus of camel,
examined without addition of any reagent. Magnified about 400 diameters. A, large colorless cell containing
small oval masses of haemoglobin. Similar ceils are found in the lymph-glands, spleen, and medulla of bone;
B, colored blood-corpuscles. (Watney).
THE CAROTID GLAND OR CAROTID BODY (GLOMUS CAROTICUM)
This body, when present, lies in the carotid bifurcation, to the inner side of the
common carotid below the bifurcation, or on the posterior surface of the internal or
of the external carotid artery. Gomez1 finds it " most commonly between the internal
and external carotid arteries, resting posteriorly on the bifurcation of the common
carotid." It is often absent. Funke found it absent in 7 foetuses out of 8. In 50
human cases examined by Gomez it was absent in 5 cases. In 4 of Gomez's cases
it was found only on one side. It lies in fatty tissue and is surrounded by a fibrous
capsule which is attached to the carotid sheath, upon which it lies by a short stump
known as the ligament of Mayer. The carotid gland is about the size of a grain of
corn; it is oval or rounded in shape and reddish-brown in color. The capsule of
the gland sends septa inward. The septa divide the organ into follicles or cell-balls.
These cell-balls are composed of endothelial cells and are associated with blood
capillaries. A branch (or branches) from the carotid artery, upon which the gland
1 American Journal of Medical Sciences, July, 1908
THE PARASYMPATHETIC BODIES 1417
lies, enters the carotid gland through the ligament of Mayer. Many nerve fila-
ments surround the carotid gland, and they usually, but not always, form a plexus,
known as the inter-carotid plexus. According to Poirier and Charpy these filaments
come from the superior cervical ganglion of the sympathetic, the glosso-pharyngeal,
the hypoglossal, the superior laryngeal, and the nervi molles of Haller. (This
structure has been recently studied by John Funke,1 Reclus and Chevasson,2
Paltauf, Kartschenko, Marchand, and Gomez.3)
Surgical Anatomy. — Tumors may arise from this structure. Such a tumor is apt to be
above the level of the upper margin of the thyroid cartilage, and in most cases it moves with
each arterial beat.
THE COCCYGEAL GLAND OR COCCYGEAL BODY OR LUSCHKA'S
GLAND (GLOMUS COCCYGEUM).
Lying near the tip of the coccyx in a small tendinous interval formed by the
union of the Levator ani muscles and just above the coccygeal attachment of
the Sphincter ani, is a small conglobate body about as large as a lentil or a pea,
first described by Luschka,4 and named by him the coccygeal gland. Its most
obvious connections are with the arteries of the part. It is similar in structure
to the carotid body.
STRUCTURE. — It consists of a congeries of small arteries with little aneurismal
dilatations derived from the middle sacral and freely communicating with each
other. These vessels are enclosed in one or more layers of polyhedral granular
cells, and the whole structure is invested in a capsule of connective tissue which
sends in trabeculae, dividing the interior into a number of spaces in which the
vessels and cells are contained. Nerves pass into this little body from the sympa-
thetic, but their mode of termination is unknown. Macalister believes the glom-
erulus of vessels "consists of the condensed and convoluted metameric dorsal
arteries of the caudal segments embedded in tissue which is possibly a small per-
sisting fragment of the neurenteric canal." It resembles the carotid gland in
structure, and is probably one of the ductless glands.
THE PARASYMPATHETIC BODIES (ORGANA PARASYMPATHETICA
OF ZUCKERKANDL).
The parasympathetic bodies were discovered in 1901 by Zuckerkandl. They are
from one to four in number, situated retroperitoneally, ventrad of the abdominal
aorta at the level of the third and fourth lumbar vertebrae. Each parasympathetic
body is from 6 to 10 mm. in length and from 2 to 4 mm. in width. These bodies
are usually supplied by fine arterial twigs from the aorta. They are best developed
in the foetus and in infancy, and in their structure they resemble the carotid and
coccygeal bodies.
i American Medicine, vol. viii.. No. 3. 2 Bull, et me"m. de la Soc. de chir. de Paris, 1903, No. 18.
3 American Journal of Medical Sciences, July. 1908.
« Der Hirnanhang und die Steissdriise des Menschen, Berlin, I860; Anatomic des Menschen, Tubingen, 1864,
vol. ii., pt. ii., p. 187.
THE UEINARY OKGAN8.
THE KIDNEYS (RENES) (Figs. 1016, 1017, 1018).
THE Kidneys are large glands. They are two in number, and are situated
in the back part of the abdomen, near the spinal column. Their function is
to separate from the blood certain materials which, when dissolved in a quantity
of water, also separated from the blood by the kidneys, constitute the urine.
INFERIOR PHRCNIC
ARTERIES
SUPERIOR W V I
MESENTERIC
ARTERY
INFERIOR
MESENTERIC
ARTERY
COMMON
ILIAC ARTERY
AND VEIN
CCELIAC
ARTERY
INTERNAL
SPERMATIC
ARTERY
AND VEIN
INTERNAL
ILIAC ARTERY
AND URETER
FIG. 1016. — Posterior abdominal wall, after removal of the peritoneum, showing kidneys, suprarenal
capsules, and great vessels. (Corning.)
They are placed in the loins, one on each side of the vertebral column, behind
the peritoneum, and are surrounded by a mass of fat and loose areolar tissue, which
constitutes the fatty capsule (capsula adiposa] (Figs. 1021 and 1022). There are
two distinct layers in this fatty capsule. The superficial fatty layer is the pararenal
fat.1 Keen calls this layer the transversalis layer of fat, because it is derived from the
1 See Gerota, Arch. f. Anatomie, Leipzic, 1895; Zuckerkandl, Medizinische Jahrbucher, Vienna, 1883.
( 1419)
1420
THE URINARY ORGANS
transversalis fascia.1 The deeper and thicker perirenal layer is the true perinephric
fat (Fig. 1022). The deeper layer of fat completely surrounds the kidney, and is
somewhat adherent to the fibrous renal capsule. The fat about the kidney does
not look like fat in other regions, but is soft, delicate, and of a canary yellow
color. These two fatty layers are separated by a layer of connective tissue, which is
the posterior layer of the perirenal fascia, and is called by Zuckerkandl the retro-
renal fascia (fascia retrorenalis) (Fig. 1021). The true capsule of the kidney (tunica
fibrosa) is thin, smooth, and glistening. The inner part of this capsule (tunica
muscularis) contains unstriated muscle fibres. The true capsule can be easily
separated from the underlying glandular structure. The upper extremity of the
kidney is on a level with the upper border of the twelfth thoracic vertebra,the lower
extremity on a level with the third lumbar vertebra (Fig. 1019). The right kidney
is usually on a slightly lower level than the left, probably on account of the vicinity
of the liver. In the female the kidneys are a little lower than in the male.
Each kidney is about four and a half inches in length, two to two and a half in
breadth, and rather more than one inch in thickness. The left is somewhat longer,
though narrower, than the right. The weight of the kidney in the adult male varies
from 4^ ounces to 6 ounces; in the adult female, from 4 ounces to 5^ ounces. The
combined weight of the two kidneys in proportion to the body is about 1 in 240.
FIG. 1017. — Anterior surface of the kidney.
(Bourgery.)
FIG. 1018. — Posterior surface of the kidney.
(Bourgery.)
The kidney has the characteristic form of a "flattened bean" (Spalteholz). It
is flattened on its sides and presents at one part of its circumference a hollow.
It is larger at its upper than at its lower extremity. The kidney presents for exam-
ination two surfaces, two borders, and an upper and lower extremity.
Surfaces. The Anterior Surface (fades anterior) (Figs. 1016 and 1017).— Its ante-
rior surface is convex, looks forward and outward, and is partially covered by peri-
toneum. The right kidney in its upper three-fourths is in contact with the pos-
terior part of the under surface of the right lobe of the liver. This area of the right
kidney is flattened (impressio hepatica). Toward its inner border it is covered by
the second part of the duodenum, while its lower and outer part is in relation with
the hepatic flexure of the colon. The relation of the second part of the duodenum
to the front of the right kidney is a varying one. The left kidney is covered above
1 W. W. Keen, in American Medicine, January 31, 1903.
THE KIDNEYS
1421
by the posterior surface of the stomach, below the stomach by the pancreas, behind
which are the splenic vessels. The region in contact with the stomach is markedly
depressed (impressio gastrica) . Its lower half is in contact with some of the coils
FIG. 1019. — Posterior surface of the kidneys. (Poirier and Charpy.)
Fio. 1020. — Relation of the kidney to the vertebral column, ribs, muscles, and lumbo-costal ligaments.
(Poirier and Charpy.)
1422
THE URINARY ORGANS
of the small intestine and sometimes with the third part of the duodenum. Near
its outer border the anterior surface lies behind the spleen and the splenic flexure
of the colon.
The kidneys are partly covered in front by peritoneum and partly uncovered.
On the right kidney, the hepatic area, that is to say that portion of the kidney
which produces the renal impression on the liver, is covered by peritoneum, which
therefore separates the kidney from the liver; the duodenal and colic areas are not
peritoneal, and these structures are connected to the kidney by loose connective
tissue; at the lower and inner extremity is a small area, the mesocolic area, which
'is covered by a layer of peritoneum of the greater sac and by the colic vessels.
On the left kidney the gastric area is covered by the peritoneum of the lesser sac;
the pancreatic and colic areas are non-peritoneal; while, as on the right side, at the
lower and inner extremity, is an area, mesocolic area, which is covered by the
peritoneum of the greater sac and by the colic vessels.
The Posterior Surface (jades posterior) (Fig. 1018). — The posterior surface of the
kidney is flatter than the anterior and is directed backward and inward. It is
ELEVENTH
RIB
TWELFTHJ
RIB
POSTERIOR
LAMELLA OF
PER I RENAL |
FASCIA
FAT BEHIND
PERIRENAL
FASCIA
PERITONEUM
ESSELS OF
ILUM OF
DNEY
SECTION
OF COLON
FIG. 1021. — Longitudinal section, showing the
arrangement of the capsule of the kidney.
(After Gerota.)
ANTERIOR
LAMELLA O
PERIRENAI
FASCIA
PERITONEUM
TRUE
PERINEPHRITIC
FAT
SACRO-LUMBALIS
GROUP
PARARCNAL
FAT
QUADRATUS LUM-
BOPUM MUSCLE
FIG. 1022. — Transverse section, showing the relations
of the capsule of the kidney and the two layers of fat.
(After Gerota.)
entirely devoid of peritoneal covering, being embedded in areolar and fatty tissue.
It lies upon the Diaphragm, the anterior layer of the lumbar aponeurosis, the
external and internal arcuate ligaments, the Psoas and Transversalis muscles,
one or two of the upper lumbar arteries, the last thoracic, ilio-hypogastric, and
ilio-inguinal nerves. The lumbo-costal ligaments overlie the posterior surface of
the kidney (Fig. 1020). The right kidney rests upon the twelfth rib (Fig. 1020),
the left usually on the eleventh and twelfth ribs. The Diaphragm separates the
kidney from the pleura as the pleura dips down to form the phrenico-costal sinus
(Fig. 1001), but frequently the muscular fibres of the Diaphragm are defective or
absent over a triangular area immediately above the external arcuate ligament,
THE KIDNEYS 1423
*
and when this is the case the perirenal areolar tissue is in immediate apposition
with the diaphragmatic pleura. In the lower part of the posterior surface of the
kidney is an impression produced by the Quadratus lumborum muscle and called
„ the impressio muscularis. A little internal to this a flattening, caused by the Psoas
muscle, is often recognizable. At the upper part of the posterior surface is a sulcus
produced by contact with the Diaphragm.
Borders. The External Border (margo lateralis) (Figs. 1017 and 1018). — The
external border is convex, and is directed outward and backward, toward the
postero-lateral wall of the abdomen. On the left side it is in contact, at its upper
part, with the spleen (Fig. 1016).
The Internal Border (margo medialis) (Figs. 1017 and 1018). — The internal bor-
der is concave, and is directed forward, inward, and a little downward. It presents
a deep longitudinal fissure, bounded by a prominent overhanging anterior and
posterior lip. This fissure is named the hilum (hilus renalis) (Fig. 1023), and
allows of the passage of the vessels, nerves, and ureter into and out of the kidney.
Extremities. The Superior Extremity (extremitas superior) (Figs. 101 7 and 1018) .
—The superior extremity, directly slightly inward as well as upward, is thick and
rounded, and is surmounted by the suprarenal capsule (Fig. 1023), which covers
also a small portion of the anterior surface.
The Inferior Extremity (extremitas inferior) (Figs. 101 7. and 1018). — The inferior
extremity, directed a little outward as well as downward, is smaller and thinner
than the superior. It extends to within two inches of the crest of the ilium.
At the hilum of the kidney the relative position of the main structures passing
into and out of the kidney is as follows: the vein is in front, the artery in the
middle, and the duct or ureter behind and toward the lower part (Fig. 1018). By
a knowledge of these relations the student may distinguish between the right and
left kidney. The kidney is to be laid on the table before the student on its
posterior surface, with its lower extremity toward the observer — that is to say,
with the ureter behind and below the other vessels; the hilum will then be directed
to the side to which the kidney belongs.
General Structure of the Kidney.— The kidney is surrounded by a distinct
investment of fibrous tissue, which forms the firm, smooth true capsule covering
the entire organ. The capsule passes over the margins of the hilum, enters the
interior of the kidney, and covers the wall of the sinus. The true capsule is
closely and firmly adherent to the renal pelvis where it is attached to the sinus.
It closely invests it, but can be easily stripped off, in doing which, however, numer-
ous fine processes of connective tissue which pass to the intrarenal connective
tissue and numerous small blood-vessels are torn through. Beneath this fibrous
layer a thin wide-meshed network of unstriped muscular fibre forms an incom-
plete covering to the organ. When the true capsule is stripped off, the surface of
the kidney is found to be smooth, even, and of a deep-red color.
In infants fissures extending for some depth may be seen on the surface of the
organ, a remnant of the lobular construction of the gland (Fig. 1040). The kid-
ney is dense in texture, but is easily lacerable by mechanical force. In order to
obtain a knowledge of the structure of the gland, a vertical section must be made
from its convex to its concave border, and the loose tissue and fat removed
around the vessels and the excretory duct (Fig. 1023). It will be then seen that
the kidney consists of a central cavity surrounded at all parts but one by the
proper kidney-substance. This central cavity is called the sinus (sinus renalis),
and is lined by a prolongation of the fibrous coat of the kidney, which enters
through a longitudinal fissure, the hilum (Fig. 1023), which is situated at that
part of the cavity which is not surrounded by kidney structure. Through this
fissure the blood-vessels of the kidney and its excretory duct pass, and there-
fore these structures, upon entering the kidney, are contained within the sinus
1424
THE URINARY ORGANS
(Fig. 1017). The excretory duct or ureter, after entering, dilates into a wide,
funnel-shaped sac named the pelvis (pelvis renalis] (Figs. 1023 and 1024). This
divides into two or three tubular divisions, which subdivide into several short,
truncated branches named calices or infundibula (calyces renales), all of which
are contained in the central cavity of the kidney (Figs. 1023 and 1024). The
blood-vessels of the kidney, after passing through the hilum, are contained in
the sinus or central cavity, lying between its lining membrane and the excretory
apparatus, before entering the kidney-substance (Fig. 1024).
This central cavity, as before mentioned, is surrounded on all sides except at
the hilum by the substance of the kidney, which is at once seen to consist of two
parts — viz., of an external granular investing part, which is called the cortical
portion (substantia corticalis} ; and of an internal part, the medullary portion (suh-
stantia medullaris), made up of a number of dark-colored pyramids, with their
bases resting on the cortical part and their apices converging toward the centre,
where they form prominent papillae, the renal papillae (papillae renales), which
project into the interior of the calices (Fig. 1023.)
SUPERIOR
EXTREMITY
MAJOR
ALICES
CUT SURFACE
OF KIDNEY
INFERIOR
EXTREMITY
FIG. 1023. — Vertical section of kidney.
FIG. 1024. — The right kidney with its pelvis exposed, view
from behind. (Spalteholz.)
The cortical substance (Figs 1023 and 1030) is of a bright reddish-brown color,
soft, granular, and easily lacerable. It is found everywhere immediately beneath
the capsule, and is seen to extend in an arched form over the base of each medul-
lary pyramid. Prolongations of the cortical substance pass between the pyramids
toward the renal sinus. These prolongations are the cortical columns or the columns
of Bertin (columnae renales] (Fig. 1023, B B). The columns contain blood-vessels,
nerves, and lymphatics. The base of each pyramid (basis pyramidis) is known
as the intermediate zone. That portion of the cortical substance which stretches
from one cortical column to the next, and intervenes between the base of the
pyramid and the capsule (marked by the dotted line extending from A to A' in Fig.
1023), is called a cortical arch, the depth of which varies from a third to half an inch.
THE KIDNEYS
1425
The medullary substance (Figs. 1023 and 1030), as before stated, is seen to con-
sist of red-colored, striated, conical masses, the pyramids of Malpighi (pyramides
renales) (Fig. 1023), the number of which, varying from eight to eighteen, corre-
sponds to the number of lobes of which the organ in the foetal state is composed.
The pyramids are composed of straight tubes which pass between the apices of
the papillae and the cortical margin. They enter the cortex in masses called the
pyramids of Ferrein (see below). The sides of the pyramids of Malpighi are con-
tiguous with the cortical columns, while the apices, known as the papillae of the
kidney (Figs. 1023 and 1027), project into the calices of the ureter, each calyx
receiving two or three papillae. Radiating from the bases of the pyramids of
Malpighi are ridges of cortical substance with distinct depressions between them.
CORTEX<
MEDULLA
AT BASE OF
;E OF<
MID I
Cun \ 01 u 1 1 » 1 lumm , &«i < i ;u i >i i i' 'i i ui »c^*Jim uuuwiuvvu tuuuic MJ wo IAJUWUUIK vlML/uaVf Ad| J.1, cuncv:
tubule, joined below by others to form the excretory duct, which opens at the apex of the pyramid. (Klein.)
These ridges are the medullary rays (pars radiata) or pyramids of Ferrein (Figs.
1026 and 1030). The labyrinth of the cortex (Fig. 1026) is constituted by the kidney
substance between the rays. The pyramids of Ferrein look like direct continua-
tions of the medullary substance, but, in reality, they are in the cortex, and are
formed by the straight tubes extending in masses into the cortex. The pyramids of
Ferrein are much smaller than the pyramids of Malpighi. In the columns of
90
1426
THE URINARY ORGANS
Bertin blood-vessels, nerves, and lymphatics pass to and emerge from the sinus
by way of small foramina. The summit of a papilla contains a number of orifices
of papillary ducts. Such an area is called an area cribrosa (Fig. 1027).
These two parts, cortical and medullary, so dissimilar in appearance, are very
similar in structure, being made up of urinary tubes and blood-vessels upited and
bound together by a connecting matrix or stroma.
Minute Anatomy. — The uriniferous tubes, urinary canals or tubuli uriniferi (tubuli
renales) (Figs. 1025 and 1030), of which the kidney is for the most part made up,
commence in the cortical portion of the kidney. Each tubule begins between the
medullary rays (Fig. 1026) in a sac, Bowman's capsule or the Malpighian capsule
(see below). The tubules, as a rule, after pursuing a very circuitous course
through the cortical and medullary parts of the kidney, finally terminate at the
apices of the Malpighian pyramids by open mouths, so that the fluid which they
contain is emptied into the dilated extremity of the ureter contained in the sinus
of the kidney. If the surface of one of the papillae is examined with a lens, it will
TUNICA
AI.BUGINEA'
LABYRINTH
OF CORTEX
MEDULLARY
RAYS
INTERLOBULAR
VEIN
r-J-JS,, CONVOLUTED
•--•"• -'TUBULES
--.=. .- MALPIGHIAN
///^-"CORPUSCLES
lts&
INTERLOBULAH
^ STRAIGHT
TUBULES
FIG. 1026. — Part of a section through the cortex of the kidney in the direction of the straight tubules. (Toldt.)
be seen to be studded over with a number of small depressions (foramina papil-
laria), from sixteen to twenty in number, and in a fresh kidney, upon pressure
being made, fluid will be seen to exude from these depressions. They are the
orifices of the tubuli uriniferi, which terminate in this situation. The tubuli uri-
niferi being in the cortex as the Malpighian bodies or corpuscles (corpuscula rents)
(Figs. 1025, 1026, 1028, and 1031), which are small rounded masses, varying in
size, but average, about y^ of an inch in diameter. They are of a deep-red color,
and are found only in the cortical portion of the kidney. Each of these little bodies
is composed of two parts — a central glomerulus of vessels, called a Malpighian
tuft, and a membranous envelope, the Malpighian capsule or capsule of Bowman
(capsula glomeruli), which latter is a small pouch-like commencement of a urinif-
erous tubule.
The Malpighian Tuft or Vascular Glomerulus (Figs. 1028, 1030, 1035, and 1036)
is a network of convoluted capillary blood-vessels held together by scanty con-
nective tissue and grouped into from two to five lobules. This capillary net-
work is derived from a small arterial twig, the afferent vessel, which pierces the wall
of the capsule, generally at a point opposite that at which the latter is connected
THE KIDXEYS
1427
with the tube; and the resulting efferent vessel emerges from the capsule at the same
point. The afferent vessel is usually the larger of the two (Fig. 1028). The Mal-
pighian or Bowman's capsule (capsula glomeruli) (Figs. 1028, 1029, and 1030), which
surrounds the glomerulus, is formed of a hyaline membrane supported by a small
amount of connective tissue which is continuous with the connective tissue of the
tube. It is lined on its inner surface with a layer of squamous epithelial cells
which are reflected from the lining membrane on to the glomerulus at the point
of entrance or exit of the afferent and efferent vessels. The whole surface of
the glomerulus is covered with a continuous layer of the same cells on a delicate
supporting membrance, which with the cells dips in between the lobules of the
glomerulus, closely surrounding them. Thus, between the glomerulus and the
capsule a space is left, forming a cavity lined by a continuous layer of cells, which
varies in size according to the state of secretion and the amount of fluid present
in it. The cells, as above stated, are squamous in the adult, but in the foetus and
young subject they are polyhedral or even columnar.
AREA CRIBROSA
EXCRETORY
TUBULES
WALL OF RENAL CALYX
FIG. 1027. — Area cribrosa of renal papilla. (Toldt.)
FIG. 1028. — Minute structure of kidney.
The Tubuli Uriniferi, commencing in the Malpighian bodies, in their course
present many changes in shape and direction (tubuli renales contorti), and are
contained partly in the medullary and partly in the cortical portions of the
organ.
At the junction of a tubule with the Malpighian capsule there is a somewhat
constricted portion which is termed the neck (Fig. 1031). Beyond this the tubule
becomes convoluted, and pursues a considerable course in the cortical structure,
constituting the proximal or first convoluted tubule (Figs. 1030 and 1031). After a
time the convolutions disappear, and the tubule approaches the medullary portion
of the kidney in a more or less spiral manner. This section of the tubule has
been called the spiral tube of Schachowa (Fig. 1031). Throughout this portion
of their course the tubuli uriniferi have been contained entirely in the cortical
structure, and have presented a pretty uniform calibre. They now enter the
medullary portion, and suddenly become much smaller, quite straight in direction
(tubuli renales recti}, and each tubule dips down for a variable depth into the
pyramids, constituting the descending limb of Henle's loop (Figs. 1030 and 1031).
Bending on itself, it forms a kind of loop near the apex of the pyramid, the
loop of Henle, and, reascending, becomes suddenly enlarged and again spiral
THE URINARY ORGANS
in direction, forming the ascending limb of Henle's loop (Figs. 1030 and 1031),
and re-enters the cortical structure. This portion of the tubule does not present
a uniform calibre, but becomes narrower as it ascends and irregular or somewhat
spiral in outline (Fig. 1031). As a narrow tube it enters the cortex and ascends
for a short distance, when it again becomes dilated, irregular, and angular. This
section is termed the irregular tubule (Fig. 1031); it terminates in a convoluted
tubule which exactly resembles the proximal convoluted tubule; and is called the
distal or second convoluted tubule (Figs. 1030 and 1031). This again terminates
in a narrow curved or junctional tubule, which enters the straight or collecting
tube.
Each straight collecting or receiving tube (Figs. 1030 and 1031) commences
by a small orifice on the summit of a papilla, thus opening and discharging
its contents into the interior of one of the calices. Traced into the substance
Afferent
and
efferent
vessels f Convo-
< luted
I tubules
Bowman's
capsule,
outer part
Blood-
Beginning of
urinary
tubule
FIG. 1029. — A section through the cortex of an ape's kidney. A Malpighian corpuscle, together with the beginning
of the urinary canal, is shown. X350.
of the pyramid, these tubes are found to run from apex to base, dividing
dichotomously in their course and slightly diverging from each other. Thus
dividing and subdividing, they reach the base of the pyramid, and enter the
cortical structure greatly increased in number. Upon entering the cortical por-
tion they continue a straight course for a variable distance, and are arranged in
groups, several of these groups corresponding to a single pyramid. The tubes in
the centre of the group are the longest, and reach almost to the surface of the kid-
ney, while the external ones are shorter, and ad'.ance only a short distance into
the cortex. In consequence of this arrangement the cortical portion presents a
number of conical masses, the apices of which reach the periphery of the organ,
and the bases are applied to the medullary portion. These are termed the medul-
THE KIDNEYS
1429
lary rays or the pyramids of Perrein (Fig. 1026; also p. 1426). As they run through
the cortical portion the straight tubes receive on either side the curved extremity
of the convoluted tubes, which, as stated above, commence at the Malpighian
bodies. Each collecting tube receives a number of tubules, and several collecting
tubes unite together to form a papillary duct (Fig. 1030) and open by a foramen
(Fig. 1027) at the surface of the papilla.
III.
IV,
Arteria ) interlob-
Ve.na J ularis
Vena ) interlob-
Arteria j ularis
FIG. 1030. — Diagrammatic representation of the course of the urinary canals (left) and the kidney vessels
(right). The arteries are red, the veins blue: capsules of Bowman, convoluted tubules I. order and loops of
Henle are black; convoluted tubules II. order and collecting tubules gray. I.. II., III., IV., four kidney
lobules: a, vas afferens; e, vas efferens. 1, Bowman's capsule; 2, convoluted tubule I. order; 3, descending
limb of loop of Henle; 4, ascending limb of loop of Henle; 5, convoluted tubule II. order; 6, 7, collecting
tubules; 8, papillary duct. (Szymonowicz.)
It will be seen from the above description that there is a continuous series
of tubes from their commencement in the Malpighian bodies to their termina-
tion at the orifices on the apices of the pyramids of Malpighi, and that the urine,
1430
THE URINARY ORGANS
Distal Jnnctional]
convo- tubule,
luted
the secretion of which commences in the capsule, finds its way through these
tubes into the calices of the kidney, and so into the ureter. To recapitulate:
the tube first presents a con-
stricted portion, (1) the neck.
2. It forms a wide convoluted
tube, the proximal convoluted
tube. 3. It becomes spiral, the
spiral tubule of Schachowa. 4. It
enters the medullary structure
as a narrow, straight tube, the
descending limb of Henle's loop.
5. Forming a loop and becom-
ing dilated, it ascends somewhat
spirally, and, gradually dimin-
ishing in calibre, again enters
the cortical structure, the as-
cending limb of Henle's loop.
6. It now becomes irregular
and angular in outline, the
irregular tubule. 7. It then be-
comes convoluted, the distal
convoluted tubule. 8. Diminish-
ing in size, it forms a curve, the
curved or junctional tubule. 9.
Finally, it joins a straight tube,
the straight collecting tube,which
is continued downward through
the medullary substance and
joins other straight tubes to
form a papillary duct, which
FIG.. 1031.— Uriniferous tube. For the sake of clearness the °PenS in a foramen »t the
epithelial cells have been represented more highly magnified than nf a nvramifl
the tubes in which they are contained. d HJrd lu'
Descending limb 1 _
of Henle's loop, j
FIG. 1032.1 — Longitu- FIG. 1033.— Longjtu-
dinal section of Henle's dinal section of straight
descending limb: a, tube: a, cylindrical or
membrana propria ; b, cubical epithelium ; b,
epithelium. membrana propria.
FIG. 1034. — Transverse section of pyramidal substance of
kidney of pig, the blood-vessels of which are injected: n, large
collecting tube cut across, lined with cylindrical epithelium;
b, branch of collecting tube cut across, lined with epithelium
with shorter cylinders; c and d. Henle's loops cut across ; e,
blood-vessels cut across ; D, connective-tissue ground-sub-
stance.
THE TUBULI URINIFERI: THEIR STRUCTURE (Figs. 1032, 1033, and 1034).—
The tubuli uriniferi consist of basement-membrane lined with epithelium. The
1 From Handbook for the Physiological Laboratory.
THE KIDNEYS
1431
epithelium varies considerably in different sections of the uriniferous tubes.
In the neck the epithelium is continuous with that lining the Malpighian
capsule, and, like it, consists of flattened cells with an oval nucleus. The cells
are, however, very indistinct and difficult to trace, and the tube has here the
appearance of a simple basement-membrane unlined with epithelium. In the
proximal convoluted tubule and the spiral tubule of Schachowa the epithelium is
polyhedral in shape, the sides of the cells not being straight, but fitting into
each other, and in some animals so fused together that it is impossible to make
out the lines of junction. In the human kidney the cells often present an angular
projection of the surface next the basement-membrane. These cells are made
up of more or less rod-like fibres, which rest by one extremity on the basement-
membrane, whilst the other projects toward the lumen of the tube. This gives
to the cells the appearance of distinct striation. In the descending limb of Henle's
loop the epithelium resembles that found in the Malpighian capsule and the
commencement of the tube, consisting of flat transparent epithelial plates with
an oval nucleus (Fig. 1032). In the ascending limb, on the other hand, the
cells partake more of the character of those described ass existing in the prox-
imal convoluted tubule, being polyhedral in shape and presenting the same
appearance of striation. The
nucleus, however, is not situ-
ated in the centre of the cell,
but near the lumen (Fig.
1034). After the ascending
limb of Henle's loop becomes
narrower upon entering the
cortical structure, the stria-
tion appears to be confined
to the outer part of the cell;
at all events, it is much more
distinct in this situation, the
nucleus, which appears flat-
tened and angular, being still
situated near the lumen. In
the irregular tubule the cells
undergo a still further change,
becoming very angular, and
presenting thick bright rods
a A
FIG. 1035. — Diagrammatic
a A
FIG. 1036.— A portion of Fig. 1035
enlarged. (The references are the
same.)
or markings, which render the sk*t'cGh' Of tfc wSHSST. of
striation much more distinct thekldn?y-
. . , . . A, a, interlobar artery and vein, the former giving off the renal
than in any Other Section OI afferent*, the latter receiving the renal efferents ; B, 6, interlobular
artery and vein, the latter commencing from the stellate veins, and
receiving branches from the plexus around the tubuli contort!, the
former giving off renal afferents ; c, straight tube, surrounded by
tubuli contort!, with which it communicates, as more fully shown in
Fig. 1036; D, margin of medullary substance ; E, E, E, receiving tubes
cut off; F, /, arteriolae et venae rectae, the latter arising from (G) the
plexus at the medullary apex; x, vascular glomerulus; w, the arcuate
artery and vein.
the urinary tubules. In the
distal convoluted tubule the
epithelium appears to be
somewhat similar to that
which has been described as
existing in the proximal convoluted tubule, but presents a peculiar refractive
appearance. In the curved tubule, just before its entrance into the straight
collecting tube, the epithelium varies greatly as regards the shape of the cells,
some being angular with short processes, others spindle-shaped, others poly-
hedral.
In the straight tubes the epithelium is more or less columnar; in its papillary
portion the cells are distinctly columnar and transparent (Fig. 1033), but as the
tube approaches the cortex the cells are less uniform in shape; some are poly-
hedral, and others angular with short processes.
1432
The Renal Blood-vessels. — The kidney is plentifully supplied with blood by
the renal artery (Figs. 1018 and 1024), a large offset of the abdominal aorta. Pre-
viously to entering the kidney, each artery divides into four or five branches,
which are distributed to its substance. At the hilum these branches lie between
the renal vein and ureter, the vein being in front, the ureter behind. Each vessel
gives off a small branch to the suprarenal capsules, the ureter, and the sur-
rounding cellular tissue and muscles. It has been pointed out by Hyrtl (p 680)
that the renal artery gives off a branch which divides and supplies the dorsal
portion of the kidney and a branch which divides and supplies the ventral
portion of the kidney. Between these two vascular systems is a non-vascular
zone, called by Robinson the exsanguinated renal zone of Hyrtl. It " is one-half inch
dorsal to the lateral longitudinal renal border." Frequently there is a second
renal artery, which is given off from the abdominal aorta at a lower level, and sup-
plies the lower portion of the kidney. It is termed the inferior renal artery. The
branches of the renal arteries pass to the kidney substance between the pyramids
and are known as interlobar arteries (arteriae interlobares renis] (Figs. 1026, 1030,
1037, and 1038). At the^junction of the cortical and medullary portions these vessels
turn and for a short distance pursue a course parallel to the kidney surface.
There are thus formed a series of incomplete vascular arches across the bases
of the pyramids, the arcuate arteries (arteriae arciformes) (Figs. 1030, 1035, and
1036). From these arches two sets of vessels come. The vessels of one set go
to the periphery and enter the labyrinth, those of the other set pass toward the
centre and enter the intermediate zone of the medulla. These last vessels are
the arteriolae recti (Figs. 1030, 1035, and 1036).
Because of these vessels the kidney exhibits stria- 6 m
tions on section. Each of the arteriolae recti
in the medulla divides into numerous small
branches which are nearly parallel to each other
FIG. 1039. — Diagrammatic representation
of the blood-vessels in the substance of the
cortex of the kidney: m, region of the
medullary ray; b. region of the tortuous
portion of the tubules; ai, interlobular
artery; vi, interlobular vein; va, vas affer-
ens; gl, glomerulus; ve. vas efferens; vz.
FIG. 1037.— Lobar circulation. FIG. 1038. — Interlobar circulation, venous twig of the interlobularis. (From
(Poirier and Charpy.) Ludwig, in Strieker's Handbook.)
and supply the tubules of this region. The arteries which arise from the arches
and pass to the periphery are the interlobular arteries (arteriae interlobulares]
(Figs. 1030, 1035, 1036, and 1039). They traverse the labyrinth and pass toward
the surface of the kidney. A number of short branches, the vasa afferentia, are
given off by the interlobular arteries (Figs. 1030, 1035, 1036, and 1039). Each
afferent vessel passes to a capsule of Bowman. On reaching the capsule the
vessel forms a capillary mass, the glomerulus, which is within the invaginated
capsule (Figs. 1030, 1035, and 1039).
Emerging from each glomerulus is a small vessel, the vas efferens (Figs.
THE KIDNEYS 1433
1028, 1030, 1035, and 1039). This vessel divides into capillaries which are dis-
tributed to the tubules of the labyrinth and medullary rays. Blood is gathered
from the capillaries about the tubules by veins which correspond to the inter-
lobular arteries and arteriolae recti. These veins form a set of arches across
the bases of the pyramids. From the arches veins arise and pass between the
pyramids to the sinus of the kidney, where they unite and form branches of
the renal vein.
Nerves of the Kidney. — The nerves of the kidney, although small, are about
fifteen in number. They have small ganglia developed upon them, and are derived
from the renal plexus, which is formed by branches from the solar plexus, the
lower and outer part of the semilunar ganglion and aortic plexus, and from the
lesser and smallest splanchnic nerves. They communicate with the spermatic
plexus, a circumstance which may explain the occurrence of pain in the testicle in
affections of the kidney. So far as they have been traced, they seem to accompany
the renal artery and its branches, but their exact mode of termination is not
known.
The Lymphatics. — The lymphatics consist of a superficial and deep set.
The superficial lymphatics are just beneath the capsule. From them come two
sets of collecting trunks (Sappey). One set joins the deep collectors by entering
the kidney substance or passing to the hilum. Another
set pass into the lymphatics of the fatty capsule.
The deep collectors emerge from the hilum and lie
about the renal artery and vein. From the right kidney
some of the trunks pass to the glands about the post-
cava and possibly also in the glands in front of the
aorta. Others end in the glands back of the postcava
(Stahr).
From the left kidney the trunks pass to the glands
which lie along the left side of the abdominal aorta.1
The lymphatics of the fatty capsule of the kidney pass
to the same glands as do the deep collectors of the
kidney (Stahr).
Connective Tissue or Intertubular Stroma. — Although
the tubules and vessels are closely packed, a certain
small amount of connective tissue, continuous with the
capsule, binds them firmly together. This tissue was Fial040i^ta(Sutj showing
first described by Goodsir, and subsequently by Bow-
man. Ludwig and Zawarykin have observed distinct fibres passing around the
Malpighian bodies, and Henle has seen them between the straight tubes com-
posing the medullary structure.
Variations and Abnormalities. — Congenital absence of the kidney has been
observed. Not unusually one kidney is considerably larger than the other; occa-
sionally one is very large and the other is very small, from atrophy, the large
organ having become large in response to a functional need, which causes it to
compensate for the insufficiency of the small kidney. If a kidney is removed
surgically, the other kidney enlarges. As previously stated, the kidneys of the
foetus and of the young child show distinct fissures which makes each organ
lobulated (Fig. 1040). The adult kidneys frequently exhibit remains of these
fissures. A horseshoe kidney is a condition in which the lower poles of the two
kidneys are united by kidney structure, the bond of union crossing the middle line.
The strip of kidney tissue which effects the junction may be slight in amount,
1 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf.
1434 THE URINARY ORGANS
considerable, or extensive. Sometimes the two kidneys are completely fused
together into one large organ with two ureters.
Surface Form. — The kidneys, being situated at the back part of the abdominal cavity and
deeply placed, cannot be felt unless enlarged or misplaced. They are situated on the confines
below the lower edge of each kidney. 2. A vertical line carried upward to the costal arch from
the middle of Poupart's ligament has one-third of the kidney to its outer side and two-thirds to
its inner side — i. e., between this line and the median line of the body." In adopting these lines
it must be borne in mind that the axes of the kidneys are not vertical, but oblique, and if con-
tinued upward would meet about the ninth dorsal vertebra. Posteriorly: The upper end of the
left kidney would be defined by a line drawn horizontally outward from the spinous process of the
eleventh dorsal vertebra, and its lower end by a point two inches above the iliac crest. The right
kidney would be half to three-quarters of an inch below. Morris lays down the following rules
for indicating the position of the kidney on the posterior surface of the body: " 1. A line parallel
with, and one inch from, the spine, between the lower edge of the tip of the spinous process
of the eleventh dorsal vertebra and the lower edge of the spinous process of the third lumbar
vertebra. 2. A line from the top of this first line outward at right angles to it for two and three-
quarter inches. 3. A line from the lower end of the first transversely outward for two and three-
quarter inches. 4. A line parallel to the first and connecting the outer extremities of the second
and third lines just described."
The hilum of the kidney lies about two inches from the middle line of the back, at the level
of the spinous process of the first lumbar vertebra.
Surgical Anatomy.— Cases of congenital absence of a kidney, of atrophy of a kidney, and
of horseshoe kidney are of great importance, and must be duly taken into account, when neph-
rectomy is contemplated. A more common malformation is where the two kidneys are fused
together. They may be only joined together at their lower ends by means of a thick mass of
renal tissue, so as to form a horseshoe-shaped body, or they may be completely united, forming
a disk-like kidney, from which two ureters descend into the bladder. These fused kidneys are
generally situated in the middle line of the abdomen, but may be misplaced as well.
One or both kidneys may be misplaced as a congenital condition, and remain fixed in this
abnormal position. They are then very often misshapen. They may be situated higher or lower
than normal or removed farther from the spine than usual or they may be displaced into the
iliac fossa, over the sacro-iliac joint, on to the promontory of the sacrum, or into the pelvis
between the rectum and bladder or by the side of the uterus. In these latter cases they may
give rise to very serious trouble. The kidney may also be misplaced as a congenital condition,
but may not he fixed. It is then known as a floating kidney. It is believed to be due to the
fact that the kidney is completely enveloped by peritoneum, which then passes backward to the
spine as a double layer, forming a mesonephron, which permits of movement taking place. The
kidney may also be misplaced as an acquired condition; in these cases the kidney is mobile in
the tissues by which it is surrounded, either moving in or moving with its fatty capsule. This
condition is known as movable kidney (nephroptosis), and is more common in the female than
in the male, and on the right than the left side. If a displaced kidney becomes fixed in an
abnormal position, it is said to be dislocated. Movable kidney cannot be distinguished from
floating kidney until the kidney is exposed by incision. Other malformations are the persist-
ence of the foetal lobulation; the presence of two pelves or two ureters to the one kidney. In
some rare instances a third kidney may be present.
The kidney is embedded in a large quantity of loose fatty tissue, and is but partially covered
by peritoneum; hence, rupture of this organ is not nearly so serious an accident as rupture of
the liver or spleen, since the extravasation of blood and urine which follows is, in the majority
of cases, outside the peritoneal cavity. Occasionally the kidney may be bruised by blows in the
loin or by being compressed between the lower ribs and the ilium when the body is violently
bent forward. This is followed by a little transient hccmaturia, which, however, speedily passes
off. Occasionally, when rupture involves the pelvis of the kidney or the commencement of the
ureter, this duct may become blocked, and hy drone phrosis follows.
The loose cellular tissue around the kidney may be the seat of suppuration, constituting
perinephritic abscess. This may be due to injury, to disease of the kidney itself, or to extension
of inflammation from neighboring parts. The abscess may burst into the pleura, causing
empyema; into the colon or bladder; or may point externally in the groin or loin. Tumors of the
kidney, of which, perhaps, sarcoma in children is the most common, may be recognized by their
position and fixity; by the resonant colon lying in front of it; by their not moving with respira-
tion; and by their rounded outline, not presenting a notched anterior margin like the spleen, with
which they are most likely to be confounded. The examination of the kidney should be bimanual ;
that is to say, one hand' should be placed in the flank and firm pressure made forward; while
THE KIDNEYS 1435
the other hand is buried in the abdominal wall, over the situation of the organ. Manipulation
of the kidney frequently produces a peculiar sickening sensation and some faintness.
The kidney has, of late years, been frequently attacked surgically. It may be exposed and
opened for exploration or the evacuation of pus (ncphrotomy); it may be incised for the removal
of stone (ncphro-lithotomy); it may be sutured when wounded (nepkrorrhaphy); it may be fixed
in place by sutures (nephropexy) or gauze pads when movable or floating; or it may be removed
(ncphrectomy).
The kidney may be exposed either by a lumbar or abdominal incision. The operation is
best performed by a lumbar incision, except in a case of very large tumor or of wandering kid-
ney with a loose mesonephron, on account of the advantages which it possesses of not opening
the peritoneum and of affording admirable drainage. It may be performed either by an oblique
a vertical, or a transverse incision. A common incision for exposing the kidney begins an inch
below the twelfth rib at the margin of the Erector spinae muscle and passes obliquely down-
ward and forward, exposing the anterior border of the Latissimus dorsi and the posterior border
of the Internal oblique. The surgeon divides the posterior leaflet of the lumbar fascia, draws aside
or incises the Quadratus lumborum,and cuts the anterior leaflet of the lumbar fascia and also the
transversalis fascia. He opens the fatty capsule down to the kidney and strips it from the true
capsule, bringing the kidney outside of the body for inspection. The vertical incision at the
edge of the Erector spinae muscle is frequently used. A gridiron or muscle-splitting operation
is used by some in order to avoid the division of nerves, vessels, and muscular fibre.
The abdominal operation is best performed by an incision in the linea semilunaris on the
side of the kidney to be removed, as recommended by Langenbuch; the kidney is then reached
from the outer side of the colon, ascending or descending, as the case may be, and the vessels
_of the colon are not interfered with. If the incision were made in the linea alba, the kidney
would be reached from the inner side of the colon, and the vessels running to supply the colon
would necessarily be interfered with. The incision is made of varying length according to the
size of the kidney, and commences just below the costal arch. The abdominal cavity is opened.
The intestines are held aside, and the outer layer of the mesocolon incised, so that the fingers
can be introduced behind the peritoneum and the renal vessels are sought for. These vessels
are then to be ligatured: if tied separately, care must be taken to ligature the artery first. The
kidney must now be enucleated, and the vessels and the ureter divided, and the latter disinfected
and tied, and, if it is thought necessary, stitched to the edge of the wound.
THE URETER (Figs. 1017, 1018, 1019, 1024, 1041, 1042).
The ureters are the two tubes which conduct the urine from the kidneys into
the bladder. The ureter commences within the sinus of the kidney by a number
of short truncated branches, the calices or infundibula, which unite either directly
or indirectly to form a dilated pouch, the pelvis (Fig. 1023), from which the ureter,
after passing through the hilum of the kidney, descends to the bladder. The calices
are cup-like tubes encircling the apices of the Malpighian pyramids; but inasmuch
as one calyx may include two or even more papillae, their number is generally
less than the pyramids themselves. The calices vary in number from eight to
eighteen. These calices converge into two or three tubular divisions which by
their junction form the pelvis or dilated portion of the ureter. The portion last
mentioned, where the pelvis merges into the ureter proper, is found opposite
the spinous process of the first lumbar vertebra, in which situation it is accessible
behind the peritoneum (Fig. 1019).
The Ureter Proper. — The ureter proper is a cylindrical membranous tube,
about sixteen inches in length and of the diameter of a goosequill, extending from
the pelvis of the kidney to the bladder. Its course is obliquely downward and
inward through the lumbar region (pars abdominalis) (Fig. 1042), into the cavity of
the pelvis (pars pelvina) (Fig. 1042), where it passes downward, forward, and inward
across that cavity to the base of the bladder, into which it then opens by a con-
stricted orifice (orificium ureteris] (Fig. 1059), after having passed obliquely for
nearly an inch between its muscular and mucous coats (Fig. 1041). The lower
part of the abdominal portion of the ureter exhibits a spindle-shaped dilatation.
Relations (Fig. 1042). — In its course it rests upon the Psoas muscle, being
covered by the peritoneum, and crossed obliquely, from within outward, by the
1436
URINARY ORGANS
spermatic vessels; the right ureter is crossed by the branches of the mesen-
teric arteries, which are distributed to the ascending colon, and the left ureter by
those for the descending colon; the right ureter lying close to the outer side of
the postcava. Opposite the first piece of the sacrum it crosses either the common
or external iliac artery and vein, lying behind the
ileum on the right side and behind the sigmoid
flexure of the colon on the left side. In the pelvis
it enters the posterior false ligament of the bladder,
below the obliterated hypogastric artery, the vas
deferens in the male passing between it and the
bladder. In the female the ureter is to the inner
side of the uterine artery at the wall of the pelvis,
it passes forward and inward below the posterior
layer of the broad ligament running through the
parametrium, passing along the side of the neck
of the uterus and upper part of the vagina,
beinff in contact with the anterior and lateral
,~ , .. i * • i • i i
vaginal walls and being crossed anteriorly by
the uterine artery (Fig. 1115). At the base of the
bladder the ureter is situated about two inches from its fellow: lying, in the male,-
about an inch and a half from the vesical orifice of the urethra, at one of the
posterior angles of the trigone (Fig. 1059).
Structure. — The ureter is composed of three coats — fibrous, muscular, and
mucous.
FIG. 1041.— Diagram showing method
of entrance of the ureter into the blad-
der. (F. H. Gemsh.)
RIGHT URETER PSOAS MUSCLE
LEFT URETER
ASCENDING
COLON
APPENDIX (drawn
up under)
ARTERIES OF
SUPERIOR
HEMORRHOIDAL
ARTERY
ARTERY TO
SIGMOID
FLEXURE
FIG. 1042. — The relations of the pelvic mesocolon with the wall, the iliac sigmoid and superior hemorrhoidal
arteries and the ureter. (Poirier and Charpy.)
The Fibrous Coat (tunica adventitia). — The fibrous coat is the same throughout
the entire length of the duct, being continuous at one end with the fibrous capsule
of the kidney at the floor of the sinus, while at the other it is lost in the fibrous
structure of the bladder.
THE URETER 1437
The Muscular Coat (tunica muscularis). — In the pelvis of the kidney the mus-
cular coat consists of two layers, longitudinal and circular: the longitudinal fibres
become lost upon the sides of the papillae at the extremities of the calices; the
circular fibres may be traced surrounding the medullary structure in the same
situation. In the ureter proper the muscular fibres are very distinct, and are
arranged in three layers — an external longitudinal (stratum externum), a middle
circular (stratum medium), and an internal layer (stratum internum), less distinct
than the other two, .but having a general longitudinal direction. According to
Kolliker, this internal layer is only found in the neighborhood of the bladder.
The Mucous Coat (tunica mucosa). — The mucous coat is smooth, and presents a
few longitudinal folds which become effaced by distention. It is continuous with
the mucous membrane of the bladder below,whilst it is prolonged over the papillae
of the kidney above. Its epithelium is of a peculiar character, and resembles that
found in the bladder. It is known by the name of transitional epithelium. It con-
sists of several layers of cells, of which the innermost — that is to say, the cells in
contact with the urine — are quadrilateral in shape, with concave margins on their
outer surface, into which fit the rounded ends of the cells of the second layer.
These, the intermediate cells, more or less resemble columnar epithelium, and are
pear-shaped, with a rounded internal extremity which fits into the concavity of
the cells of the first layer, and a narrow external extremity which is wedged in
between the cells of the third layer. The external or third layer consists of conical
or oval cells varying in number in different parts, and presenting processes which
extend down into the basement-membrane.
Vessels and Nerves. — The arteries supplying the ureter are branches from the
renal, spermatic, internal iliac, and inferior vesical.
The nerves are derived from the inferior mesenteric, spermatic, and pelvic plexuses.
Surgical Anatomy. — Subcutaneous rupture of the ureter is not a common accident, but occa-
sionally occurs from a sharp, direct blow on the abdomen, as from the kick of a horse. The ureter
may be either torn completely across, or only partially divided, and, as a rule, the peritoneum
escapes injury. If torn completely across the urine collects in the retroperitoneal tissues; if it
is not completely divided, the lumen of the tube may become obstructed and hydro-nephrosis or
pyo-nephrosis results. The ureter may be accidentally wounded in some abdominal operations;
if this should happen, the divided ends must be sutured together, or, failing to accomplish this,
the upper end must be implanted into the bladder or the intestine.
THE SUPRARENAL CAPSULE OR GLAND (GLANDULA
SUPRARENALISj (Figs. 1023, 1043, 1044).
The suprarenal capsules belong to the class of ductless glands. They are two
small flattened bodies, of a yellowish color, situated at the back part of the abdo-
men, behind the peritoneum, and immediately above and in front of the upper
end of each kidney; hence their name. The right one (Fig. 1043) is somewhat
triangular in shape, bearing a resemblance to a cocked hat; the left (Fig. 1044) is
more semilunar, usually larger and placed at a higher level than the right. They
vary in size in different individuals, being sometimes so small as to be scarcely
detected ; their usual size is from an inch and a quarter to nearly two inches in
length, rather less in width, and from two to three lines in thickness. Their
average weight is from one to one and a half drachms each.
Relations. — The relations of the suprarenal capsules differ on the two sides oi
the body.
The Right Suprarenal (Fig. 1043).— The right suprarenal is roughly triangular in
shape, its angles pointing upward, downward, and outward. It presents two sur-
faces for examination, an anterior and a posterior. The anterior surface (fades
1438 THE URINARY ORGANS
anterior) presents two areas, separated by a furrow, the hilum (hilus glandulae
suprarenatis] : one area occupying about one-third of the whole surface, is situ-
ated above and internally; it is depressed, uncovered by peritoneum, and is in
contact in front with the posterior surface of the right lobe of the liver, and along
its inner border with the postcava; the remaining area is elevated, and is divided
into a non-peritoneal portion, in contact with the hepatic flexure of the duodenum,
and a portion covered by peritoneum forming the hepato-renal fold. The pos-
terior surface (fades posterior) is slightly convex, and rests upon the Diaphragm.
The base (basis glandulae suprarenalis] is concave, and is in contact with the upper
end and the adjacent part of the anterior surface of the kidney.
The Left Suprarenal (Fig. 1044). — The left suprarenal is crescentic in shape, its
concavity being adapted to the upper end of the left kidney. It presents an inner
SUPRARENAL
SUPRARENAL
ARTERY
SUPRARENAL
SUPRARENAL «pT ^ 9 ARTERY
VEIN "
FIG. 1043. — The right suprarenal gland. FIG. 1044. — The left suprarenal gland.
(Spalteholz.) (Spalteholz.)
border which is convex, and an outer which is concave ; its upper border is narrow,
and its lower rounded. Its anterior surface (jades anterior] presents two areas: an
upper one, covered by the peritoneum forming the lesser sac, which separates it
from the cardiac end of the stomach and to a small extent from the superior
extremity of the spleen; and a lower one, which is in contact with the pancreas
and splenic artery, and is therefore not covered by the peritoneum. A hilum is
present, as in the right suprarenal. Its posterior surface (fades posterior] presents
a vertical ridge, which divides it into two areas. The ridge lies in the sulcus
between the kidney and crus of the Diaphragm, while the area on either side of
it lies on these parts respectively; the outer area, which is thin, resting on the
kidney, and the inner and smaller area resting on the left crus of the Diaphragm.
The surface of the suprarenal gland is surrounded by areolar tissue containing
much fat, and closely invested by a thin fibrous coat, which is difficult to remove,
on account of numerous fibrous processes and vessels which enter the organ
through the furrows on its anterior surface and base.
Accessory Suprarenal Glands (glandulae suprarenales accessoriae]. — Small
accessory suprarenals are often to be found in the connective tissue around the
suprarenals. The smaller of these, on section, show a uniform surface, but in
some of the larger a distinct medulla can be made out.
Structure (Figs. 1045, 1046, and 1047). — On making a perpendicular section
(Fig. 1045), the suprarenal gland is seen to" consist of two substances — external or
cortical and internal or medullary. The former, which constitutes the chief part of
the organ, is of a deep- yellow color. The medullary substance is soft, pulpy,
THE SUPRARENAL CAPSULE Oil GLAND
1430
and of a dark-brown or black color, whence the name atrabiliary capsules formerly
given to these organs. In the centre is often seen a space, not natural, but
formed by breaking down after death of the medullary substance.
The Cortical Portion (substantia corticalis] (Fig. 1045). — The cortical substance
consists chiefly of narrow columnar masses placed perpendicularly to the surface.
This arrangement is due to the disposition of the capsule, which sends into the
interior of the gland processes passing in vertically and communicating with each
other by transverse bands so as to form spaces
which open into each other. These spaces are
of slight depth near the surface of the organ,
so that there the section somewhat resembles a
net; this is termed the zona glomerulosa ; but
they become much deeper or longer farther in,
so as to resemble pipes or tubes placed endwise,
'apsule.
Zona
glomerulosa.
Zona
fasciculata.
Connective
tissue.
Gland
cylinders.
FIG. 1046. — Minute structure of suprarenal
capsule.
Framework.
Zona reticularis.
Medulla.
Nuclei.
Capillary.
FIG. 1045. — Vertical section of the suprarenal capsule. (From
Elberth, in Strieker's Manual.)
Gland
cells.
FIG. 1047. — Minute structure of suprarenal
capsule.
the zona fasciculata. Still deeper down, near the medullary part, the spaces
become again of small extent; this is named the zona reticularis. These processes
or trabeculae, derived from the capsule and forming the framework of the spaces,
are composed of fibrous connective tissue with longitudinal bundles of unstriped
muscular fibres. Within the interior of the spaces are contained groups of poly-
hedral cells, which are finely granular in appearance, and contain a spherical
nucleus, and not infrequently fat-globules. These groups of cells do not entirely
fill the spaces in which they are contained, but between them and the trabeculae
of the framework is a channel which is believed to be a lymph-path or sinus,
and which communicates with certain passages between the cells composing the
1440 THE URINARY ORGANS
group. The lymph-path is supposed to open into a plexus of efferent lymphatic
vessels which are contained in the capsule.
The Medullary Portion (substantia medullaris) (Fig. 1045). — In the medullary
portion the fibrous stroma seems to be collected together into a much closer
arrangement, and forms bundles of connective tissue which are loosely applied
to the large plexus of veins of which this part of the organ mainly consists. In
the interstices lie a number of cells compared by Frey to those of columnar epithe-
lium. They are coarsely granular, do not contain any fat-molecules, and some
of them are branched. Luschka has affirmed that these branches are connected
with the nerve-fibres of a very intricate plexus which is found in the oblongata; this
statement has not been verified by other observers, for the tissue of the medullary
substance is less easy to make out than that of the cortical, owing to its rapid
decomposition.
Vessels and Nerves. — The numerous arteries which enter the suprarenal bodies
from the sources mentioned below penetrate the cortical part of the gland, where
they break up into capillaries in the fibrous septa, and these converge to the very
numerous veins of the .medullary portion, which are collected together into the
suprarenal vein, which usually emerge as a single vessel from the centre of the
gland.
The arteries supplying the suprarenal capsules are three in number and of large
size; they are derived from the aorta, the phrenic, and the renal; they subdivide
into numerous minute branches previous to entering the substance of the gland.
The suprarenal vein returns the blood from the medullary venous plexus,
and receives several branches from the cortical substance; it emerges from the
hilum and opens on the right side into the postcava, on the left side into the renal
vein.
The lymphatics form several collections which are about the beginning of the
suprarenal vein. They terminate in the glands to the corresponding side of the
aorta.
The nerves are exceedingly numerous, and are derived from the solar and
renal plexuses, and, according to Bergmann, from the phrenic and vagus nerves.
They enter the lower and inner part of the capsule, traverse the cortex, and ter-
minate about the cells of the oblongata. They have numerous small ganglia
developed upon them, from which circumstance the organ has been conjectured
to have some function in connection with the sympathetic nerve system.
THE CAVITY OF THE PELVIS.
The cavity of the pelvis is that part of the general abdominal cavity which is
below the level of the ilio-pectineal lines and the promontory of the sacrum.
Boundaries. — It is bounded behind by the sacrum, the coccyx, the Pyriformis
muscles, and the great sacro-sciatic ligaments; in front and at the sides by the
portions of the innominate bones below the ilio-pectineal lines. In front and
to the sides the bony sides of the pelvic cavity are partly covered by the internal
Obturator muscles,* and internal to these muscles by the parietal part of the
pelvic fascia. Above, it communicates with the cavity of the abdomen; and
below, the outlet is closed by the triangular ligament, the Levatores ani and
Coccygei muscles, and the visceral layer of the pelvic fascia, which is reflected
from the wall of the pelvis on to the viscera.
Contents. — The viscera contained in this cavity are — the urinary bladder, the
rectum, and some of the generative organs peculiar to each sex, and some convo-
lutions of the small intestines. The pelvic viscera are partially covered by the
Deritoneum, and supplied with blood-vessels, lymphatics, and nerves.
THE URINARY BLADDER
1441
THE URINARY BLADDER (VESICA URINARIA) (Figs. 1050, 1051, 1069, 1070).
The urinary bladder is the reservoir for the urine. It is a musculo-membranous
sac situated in the pelvis, behind the pubes, and in front of the rectum in the male,
the cervix uteri and vagina intervening between it and that intestine in the female.
The shape, position, and relations of the bladder are greatly influenced by age,
FIG. 1048.— The empty bladder. (Poirier and Charpy.)
FIG. 1049.— M9difications 9f form of the blad-
der during distention (Poirier and Charpy.)
sex, and the degree of distention of the organ. During infancy it is conical in
shape, and projects above the symphysis pubis into the hypogastric region. In the
adult, when quite empty and contracted (Figs. 1048 and 1049), it is cup-shaped,
and on vertical median section its cavity, with the adjacent portion of the urethra,
presents a Y-shaped cleft, the stem of the Y corresponding to the urethra. It is
PERITONEUM
RECTO-
VESICAL
POUCH
PROSTATE AND
SEMINAL VESICLES
FIG. 1050. — Mesal section through pelvis of new-born male. (Corning.)
placed deeply in the pelvis, flattened from before backward, and reaches as high as
the upper border of the symphysis pubis. When slightly distended, it has a rounded
form, and is still contained within the pelvic cavity (Fig. 1049), and when greatly
distended (Figs. 1049 and 1051), it is ovoid in shape, rising into the abdominal
cavity, and often extending nearly as high as the umbilicus. 'It is larger in its verti-
cal diameter than from side to side, and its long axis is directed from above
obliquely downward and backward, in a line directed from some point between
the symphysis pubis and umbilicus (according to its distention) to the end of the
coccyx. The bladder, when distended, is slightly curved forward toward the
anterior wall of the abdomen, so as to be more convex behind than in front. In
the female it is larger in the transverse than in the vertical diameter, and its
91
1442
THE URINARY ORGANS
capacity is said to be greater than in the male.1 When moderately distended, it
measures about five inches in length, and three inches across, and the ordinary
amount which it can contain without serious discomfort is about a pint.
The bladder is divided for purposes of description into a superior, an antero-
inferior, and two lateral surfaces, a base or fundus, and a summit or apex.
Surfaces. The Superior or Abdominal Surface (Figs. 865, 1051, 1052, and 1070).
—The superior or abdominal surface is entirely free, and is covered throughout by
Prostatic p^
of urethra.
Ejaculatory duct.
CTER AMI.
Prostatic/
sinuses.
Fossa
-navicularis.
Prepuce.-—-'
FIG. 1051. — Vertical section of bladder, penis, and urethra.
peritoneum. It looks almost directly upward into the abdominal cavity, and extends
in an antero-posterior direction from the apex to the base of the bladder. It is in
relation with the small intestine and sometimes with the sigmoid flexure, and, in
the female, with the uterus. On each side, in the male, a portion of the vas
deferens is in contact with the hinder part of this surface, lying beneath the
peritoneum.
The Antero-inferior or Pubic Surface (Figs. 1051, 1052, and 1070). — The antero-
inferior or pubic surface looks downward and forward. In the undistended
condition it is uncovered by peritoneum, and is in relation with the Obturator
internus muscle on each side, with the recto-vesical fascia, and anterior true
ligaments of the bladder. It is separated from the body of the pubis by a tri-
angular interval, the space of Retzius, occupied by fatty tissue. As the bladder
ascends into the abdominal cavity during distention the distance between its apex
and the umbilicus is necessarily diminished, and the urachus (Fig. 865 and 1070)
is thus relaxed; so that, instead of passing directly upward to the umbilicus, it
descends first on the upper part of the anterior surface of the bladder, and then,
i According to Henle, the bladder is considerably smaller in the female than in the male. — ED. of 15th
English edition.
THE URINARY BLADDER
1443
curving upward, ascends on the back of the abdominal wall. The peritoneum,
which follows the urachus, thus comes to form a pouch (plica vesicalis transversa)
of varying depth between the anterior surface of the viscus and the abdominal
wall (Fig. 1052). The fold passes to the neighborhood of the internal abdom-
inal rings. Thus, when the bladder is distended, the upper part of its anterior
surface is in relation with the urachus and is covered by peritoneum. The lower
part of its anterior surface, a distance of about two inches above the symphysis
pubis, is devoid of peritoneum, and is in contact with the abdominal wall.
AREOLO-
TISSUE CON
TAINING VEINS
INTERNAL
SPHINC-
TER ANI
COM-
PRESSOR
URETHR/E
EXTERNAL
SPHINC-
TER ANI
NOSUS MUSCLE
FIG. 1052. — Vertical median section of the male pelvis. (Henle.)
The Lateral Surfaces. — The lateral surfaces are covered behind and above by
peritoneum, which extends as low as the level of the obliterated hypogastric
artery; below and in front of this, these surfaces are uncovered by peritoneum,
and are separated from the Levatores ani muscles and walls of the pelvis by a
quantity of loose areolar tissue containing fat. In front this surface is connected
to the recto-vesical fascia by a broad expansion on either side, the lateral true
ligaments. The vas deferens crosses the hinder part of the lateral surface obliquely,
and passes between the ureter and the bladder. When the bladder is empty the
peritoneum descends on the pelvic wall as low as the lateral border of the bladder
and enters a groove known as the paravesical fossa. The lateral surfaces, the
pubic surface, and the abdominal surface together constitute the body of the
bladder (corpus vesicae).
The Fundus or Base (fundus vesicae) (Figs. 1052, 1067, and 1070). — The fundus
or base is directed downward and backward, and is partly covered by peritoneum
1444
THE URINARY ORGANS
and is in part not covered by it. In the male the upper portion, to within about
an inch and a half of the prostate, is covered by the recto-vesical pouch of peri-
toneum (Fig. 868). The lower part is in direct contact with the anterior wall of
the second part of the rectum and the vesiculse seminales and vasa deferentia
(Figs. 1067 and 1069). - The ureters enter the bladder at the upper part of its
base, about an inch and a half above the base of the prostate gland (Fig. 1059).
Vermiform appendix.
External iliac Anterior crural External oblique
, artery. . nerve. muscle.
V
Profunda vessels. "-EVATOR ANI. Corpora Urethra.
FIG. 1053. — Frontal section of the lower part of the abdomen. Viewed from in front. (Braune.)
The portion of the bladder in relation with the rectum corresponds to a trian-
gular space, bounded, below, by the prostate gland; above, by the recto-vesical
fold of the peritoneum; and on each side, by the vesicula seminalis and vas
deferens. It is separated from direct contact with the rectum by (he recto-
vesical fascia. When the bladder is very full, the peritoneal fold is raised with
it, and the distance between its reflection and the anus is about four inches; but
this distance is much diminished when the bladder is empty and contracted. In
the female, the base of the bladder is connected to the anterior aspect of the cervix
uteri by areolar tissue, and is adherent to the anterior wall of the vagina (Fig.
866). Its upper surface is separated from the anterior surface of the body of
the uterus by the utero-vesical pouch of the peritoneum (Fig. 866).
The so-called neck or cervix of the bladder (collum vesicae) is the point of com-
mencement of the urethra; there is, however, no tapering part, which would
constitute a true neck, but the bladder suddenly contracts to the opening of the
urethra (Fig. 1052). In the male it is surrounded by the prostate gland and its
direction is oblique when the individual is in the erect posture (Figs. 1051 and
1 052). In the female its direction is obliquely downward and forward.
1445
The Summit or Apex (vertex vesicae). — The summit or apex is the portion
of the bladder which when that organ is empty or nearly empty is nearest to
the upper border of the symphysis. It is directed upward and forward. In a
distended bladder the apex is well above the pubes in the abdominal cavity.
The Urachus or Middle Umbilical Ligament (ligamentum umbilicale medium)
(Fig. 1070). — The urachus is a connective-tissue cord and is the obliterated
remains of the tubular canal of the allantois, which existed in the embryo, and
a portion of which expanded to form the bladder. It passes upward, from the
apex of the bladder, between the transversalis fascia and peritoneum, to the
umbilicus, becoming thinner as it ascends. It is composed of fibrous tissue,
mixed with plain muscular fibres. The urachus causes the formation of a peri-
toneal fold, the plica umbilicalis media (Fig. 865). On each side of it is placed a
fibrous cord, the obliterated portion of the hypogastric artery, which, passing
upward from the side of the bladder, approaches the urachus above its summit.
Over each cord is the fold known as the plica umbilicalis lateralis (Fig. 865). In
the infant, at birth, the urachus is occasionally found pervious, so that the urine
escapes at the umbilicus, and calculi have been found in its canal.
Ligaments. — The bladder is retained in its place by ligaments, which are divided
into true and false. The true ligaments are five in number: two anterior, two
lateral, and the urachus. The false ligaments, also five in number, are formed by
folds of the peritoneum.
The two anterior true ligaments, the pubo-prostatic or pubo-vesical ligaments (liga-
menta puboprostatica) extend from the back of the ossa pubis, one on each side of
the symphysis, to the front of the neck of the bladder, over the anterior surface of
the prostate gland. These ligaments are formed by the recto-vesical fascia, and
contain a few muscular fibres prolonged from the bladder.
The two lateral true ligaments, formed by expansions from the fascia lining the
lateral wall of the pelvis, are broader and thinner than the preceding. They
are attached to the lateral parts of the prostate gland and to the sides of the base of
the bladder.
Fir.. 1054.— Fibres of the external
longitudinal layer. (Poirier and
Charpy.)
FIG. 1055. — Fibres of the middle
or circular layer. (Poirier and
Charpy.)
FIG. 1056. — Fibres of the inter-
nal longitudinal layer. (Poirier
and Charpy.)
The urachus or middle umbilical ligament is the fibro-muscular cord already men-
tioned, extending between the summit of the bladder and the umbilicus. It is broad
below, at its attachment to the bladder, and becomes narrower as it ascends.
1446 THE URINARY ORGANS
The two posterior false ligaments pass forward, in the male, from the sides of
the rectum (plicae rectovesicales) ; in the female, from the sides of the uterus (plicae
rectouterinae) to the posterior and lateral aspect of the bladder; they form in
the male the lateral boundaries of the recto-vesical pouch (excavatio rectovesicalis)
(Figs. 939 and 1052) ; they form in the female the lateral boundaries of the pouch or
cul-de-sac of Douglas (excavatio rectouterina [Douglasi]) (Figs. 866 and 940). The
posterior false ligaments contain the obliterated hypogastric arteries and the
ureters, together with vessels and nerves. In the base of each fold is smooth
muscle-fibre, the Recto-vesical muscle (m. rectovesicalis}.
The two lateral false ligaments are reflections of the peritoneum, from the
iliac fossae and lateral walls of the pelvis to the sides of the bladder. Each
lateral false ligament (ligamentum umbihcale later ale) passes in front into the plica
umbilicalis lateralis over the corresponding hypogastric artery. The two lateral
reflections of peritoneum are continuous in front of the apex vesicae, at which
point the peritoneum passes upon the urachus.
The superior or anterior false ligament or the suspensory ligament (plica umbilicalis
media) is the prominent fold of peritoneum extending from the summit of the blad-
der to the umbilicus. It is carried off from the bladder by the urachus and the
obliterated hypogastric arteries. The peritoneal fold over each obliterated hypo-
gastric artery is called the plica umbilicalis lateralis (Fig. 865), and is the pro-
longation forward of the ligamentum umbilicale laterale. Besides the true and
false ligaments, the bladder receives support from the fibrous tissue and unstriated
muscle about the seminal vesicles, and terminations of the ureters and vasa defer-
entia. In the female the connection with the anterior vaginal wall supports the
base of the bladder. In both sexes the most solidly fixed part of the bladder is
about the orifice of the urethra.
Structure. — The bladder is composed of four coats — serous, muscular, sub-
mucous, and mucous.
The Serous Coat (tunica serosa). — The serous coat is partial, and derived from the
peritoneum. It invests the superior surface and the upper part of the lateral surfaces
and base, and is reflected from these parts on to the abdominal and pelvic walls.
The Muscular Coat (tunica muscularis) (Figs. 1054, 1055, and 1056). ^The mus-
cular coat consists of three layers of unstriped muscular fibre : an external layer,
composed of fibres having for the most part a longitudinal arrangement; a middle
layer, in which the fibres are arranged, more or less, in a circular manner; and an
internal layer, in which the fibres have a general longitudinal arrangement.
The fibres of the external longitudinal layer (stratum externum) arise from the
posterior surface of the body of the os pubis in both sexes (m. pubovesicalis) , and
in the male arise also from the adjacent part of the prostate gland and its capsule.
They pass, in a more or less longitudinal manner, up the anterior surface of the
bladder, over its apex, and then descend along its posterior surface to its base,
where they become attached to the prostate in the male and to the front of the vagina
in the female. At the sides of the bladder the fibres are arranged obliquely and
intersect one another. The external lorgitudinal layer has been named the
Detrusor urinae muscle.
The middle circular layers (stratum medium) are very thinly and irregularly
scattered on the body of the organ, and, though to some extent placed transversely
to the long axis of the bladder, are for the most part arranged obliquely. Toward
the lower part of the bladder, around the neck and the commencement of the
urethra, they are disposed in a thick circular layer, forming the sphincter vesicae,
which is continuous with the muscular fibres of the prostate gland.
The internal longitudinal layer (stratum internum) is thin, and its fasciculi have
a reticular arrangement, but with a tendency to assume for the most part a longi-
tudinal direction. Two bands of oblique fibres, originating behind the orifices of
the ureters, converge to the back part of the prostate gland, and are inserted, by
THE URINARY BLADDER 1447
means of a fibrous process, into the middle lobe of that organ. They are the
muscles of the ureters, described by Sir C. Bell, who supposed that during the con-
traction of the bladder they served to retain the oblique direction of the ureters,
and so prevent the reflux of the urine into them.
The Submucous Coat (tela submucosd). — The submucous coat consists of a layer
of areolar tissue connecting together the muscular and mucous coats, and inti-
mately united to the latter.
The Mucous Coat (tunica mucosa). — The mucous coat is thin, smooth, and of a
pale rose color. It is continuous above through the ureters with the lining mem-
brane of the uriniferous tubes, and below with that of the urethra. Except at the
trigone, it is connected very loosely to the muscular coat by a layer of areolar tissue,
and is therefore thrown into folds or rugae when the bladder is empty (Fig.
1060). The mucous membrane over the trigone never presents rugae. The
epithelium covering it is of the transitional variety, consisting of a superficial
layer of polyhedral flattened cells, each with one, two, or three nuclei (Fig. 1057) ;
beneath these is a stratum of large club-shaped cells with the narrow extremity of
each cell directed downward and wedged in between smaller spindle-shaped cells,
each an oval nucleus (Fig. 1058). There are no true glands in the mucous mem-
brane of the bladder, though certain mucous follicles which exist, especially near
the neck of the bladder, have been regarded as such.
Objects Seen on the Inner Surface.— Upon the inner surface of the bladder are
seen the mucous membrane, orifices of the ureters, the trigone, and the commencement
of the urethra.
FIG. 1057. — Superficial layer of the epithelium of FIG. 1058. — Deep layers of epithelium of bladder,
the bladder. Composed of polyhedral cells of vari- showing large club-shaped cells above, and smaller,
ous sizes, each with one, two, or three nuclei. (Klein more spindle-shaped cells below, each with an oval
and Noble Smith.) nucleus. (Klein and Noble Smith.)
The Mucous Membrane. — The mucous membrane of the empty bladder is thrown
into folds or rugae, except over the trigone, where it is firmly adherent to the
muscular coat and is smooth (Figs. 1059 and 1060). The folds disappear when
the bladder is distended.
The Orifices of the Ureters (Figs. 1059 and 1060). — These are situated at the base
of the trigone, being distant from each other about two inches when the bladder is
moderately distended. Each orifice is about an inch and a half from the base of the
prostate and the commencement of the urethra in the moderately distended bladder.
The Vesical Trigone or the Trigonum Vesicae (Fig. 1060) is a triangular smooth
surface, with the apex directed forward, situated at the base of the bladder, imme-
diately behind the urethral orifice. It is paler in color than the rest of the
interior, and never presents any rugae, even in the collapsed condition of the
organ, owing to the intimate adhesion of its mucous membrane to the subjacent
tissue. It is bounded at each posterior angle by the orifice of a ureter, and in
front by the orifice of the urethra. Projecting from the lower and anterior part of
the bladder, and reaching to the orifice of the urethra, is a slight elevation of
mucous membrane, particularly prominent in old persons, called the uvula vesicae.
It is formed by a thickening of the submucous tissue.
1448
Stretching from one ureteral opening to the other is a smooth, slightly curved
ridge, the convexity of which is toward the urethra. It is produced by transverse
muscle-fibres beneath the mucous membrane. The outer prolongations of this
ridge beyond the ureteral orifices are called the ureteral folds (plicae uretericae).
They are created by the ureters as they traverse the bladder wall. About the
ureteral orifice are slight radial folds of mucous membrane, which are continuous
with the longitudinal folds of the prostatic urethra. "In the empty bladder the
ureteral orifice and the openings of the two ureters lie at the angles of an approxi-
mately equilateral triangle, whose sides are about one inch in length. When the
bladder is distended the distance between the openings may be increased to one
and a half inches or more."1
RIDGE FORMrD BY
J-INTERURETERAL
MUSCLE
FIG. 1059. —The interior of the bladder, showing the vesical trigone. (Poirier and Charpy.)
CIRCULAR
FIBRES
TRIGONE
TRANSVERSE
FIBRES OF
TRIGONE
LONGITUDINAL
FIBRES OF
TRIGONE
EJACULATORY
DUCT
Fio. 1060. — The internal surface of the bladder. (Poirier and Charpy.)
i Professor A. Francis Dixon, in Prof. D. J. Cunningham's Text-book of Anatomy.
THE URINARY BLADDER 1449
The muscles of the ureters were referred to on p. 1447.
The internal urethral orifice (orificium urethrae intcrnum) is sickle-shaped and
is surrounded by a circular prominence (annulus urethralis}, which is most distinct
in the male.
Vessels and Nerves. — The arteries (Fig. 427) supplying the bladder are the
superior, middle, and inferior vesical in the male, with additional branches from
the uterine and vaginal in the female. They are all derived from the anterior
trunk of the internal iliac. The obturator and sciatic arteries also supply small
visceral branches to the bladder. The veins form a complicated plexus around the
neck, sides, and base of the bladder (Fig. 474). The veins communicate below
with the plexus about the prostate and terminate in the internal iliac vein.
The lymphatics form two plexuses, one in the muscular and another in the sub-
mucous coat. They accompany the blood-vessels. The mucous membrane of
the bladder contains no lymphatics whatever (Sappey). The muscular tissue
contains a few lymphatics. The subperitoneal tissues contain the usual number.
The collecting trunks from the anterior surface terminate in the external iliac
glands. The trunks from the posterior surface terminate in the internal iliac
glands, the hypogastric glands and the glands in front of the sacral promontory.
The nerves are derived from the pelvic plexus of the sympathetic and from the
third and fourth sacral nerves ; the former supplying the upper part of the organ,
the latter its base and neck. According to F. Darwin, the sympathetic fibres have
ganglia connected with them, which send branches to the vessels and to the
muscular coat.
Surface Form.— The surface form of the bladder varies with its degree of distention and
under other circumstances. In the young child it is represented by a conical figure, the apex
of which, even when the viscus is empty, is situated in the hypogastric region, about an inch
above the level of the symphysis pubis. In the adult, when the bladder is empty, its apex does
not reach above the level of the upper border of the symphysis pubis, and the whole organ is
situated in the pelvis; the neck, in the male, corresponding to a line drawn horizontally backward
through the symphysis a little below its middle. As the bladder becomes distended, it gradually
rises out of the pelvis into the abdomen, and forms a swelling in the hypogastric region, which is
perceptible to the hand as well as to percussion. In extreme distention it reaches into the umbil-
ical region. Under these circumstances the lower part of its anterior surface, for a distance
of about two inches above the symphysis pubis, is closely applied to the abdominal wall, without
the intervention of peritoneum, so that it can be tapped by an opening in the middle line just
above the symphysis pubis, without any fear of wounding the serous membrane. When the
rectum is distended, the prostatic portion of the urethra is elongated and the bladder lifted out
of the pelvis and the peritoneum pushed upward. Advantage is taken of this by some surgeons
in performing the operation of suprapubic cystotomy. The rectum is distended by an India-
rubber bag, which is introduced into this cavity empty, and is then filled with ten or twelve ounces
of water. If now the bladder is injected with about half a pint of some antiseptic fluid, it will
appear above the pubes plainly perceptible to the sight and touch. The peritoneum will be
pushed out of the way, and an incision three inches long may be made in the linea alba, from
the symphysis pubis upward, without any great risk of wounding the peritoneum. Other sur-
geons object to the employment of this bag, as its use is not unattended with risk, and because
it causes pressure on the prostatic veins and hence produces congestion of the vessels over the
bladder and a good deal of venous hemorrhage.
When distended, the bladder can be felt in the male, from the rectum, behind the prostate,
and fluctuation can be perceived by a bimanual examination, one finger being introduced into the
rectum and the distended bladder being tapped on the front of the abdomen with the finger
of the other hand. This portion of the bladder — that is, the portion felt in the rectum by the
finger — is uncovered by peritoneum.
Surgical Anatomy. — A certain defect of development in which the bladder is implicated is
known under the name of extroversion of the bladder. In this condition the lower part of the
abdominal wall and the anterior wall of the bladder are wanting, so that the posterior surface
of the bladder presents on the abdominal surface, and is pushed forward by the pressure of the
viscera within the abdomen, forming a red, vascular protrusion, on which the openings of the
ureters are visible. The penis, except the glans, is rudimentary and is cleft on its dorsal sur-
face, exposing the floor of the urethra — a condition known as epispadias. The pelvic bones
are also arrested in development (see page 222).
The bladder may be ruptured by violence applied to the abdominal wall when the viscus is
1450 THE URINARY ORGANS
distended without any injury to the bony pelvis, or it may be torn in case of fracture of the
pelvis. The rupture may be either intraperitoneal or extraperitoneal — that is, may implicate the
superior surface of the bladder in the former case, or one of the other surfaces in the latter.
Rupture of the antero-inferior surface alone is, however, very rare. Until recently intraperi-
toneal rupture was uniformly fatal, but now abdominal section and suturing the rent with Lem-
bert sutures often saves the patient. The sutures are inserted only through the peritoneal and
muscular coats in such a way as to bring the serous surfaces at the margins of the wound into
apposition, and one is also inserted just beyond each end of the wound. The bladder should be
tested as to whether it is water-tight before closing the external incision.
The muscular coat of the bladder undergoes hypertrophy in cases in which there is any per-
sistent obstruction to the flow of urine. Under these circumstances the bundles of which the
muscular coat consists become much increased in size, and, interlacing in all directions, give rise
to what is known as the fasciculated bladder. Between these bundles of muscular fibres the mucous
membrane may bulge out, forming sacculi, constituting the sacculated bladder, and in these
little pouches phosphatic concretions may collect, forming encysted calculi. The mucous mem-
brane is very loose and lax, except over the trigone, to allow of the distention of the viscus.
Various forms of tumors have been found springing from the wall of the bladder. The inno-
cent tumors are the papilloma and the mucous polypus, arising from the mucous membrane;
the fibrous tumor, from the submucous tissue; and the myoma, originating in the muscular
tissue; and, very rarely, derrnoid tumors, the exact origin of which it is difficult to explain.
Of the malignant tumors, epitheliomata are the most common, but sarcomata are occasionally
found in the bladders of children.
Puncture of the bladder is performed above the pubes without wounding the peritoneum.
Puncture by the rectum is not now performed, as a permanent fistula may be left from abscess
forming between the rectum and the bladder; or pelvic cellulitis maybe set up; moreover, it is
exceedingly inconvenient to keep a cannula in the rectum. In some cases in performing this
operation the recto-vesical pouch of peritoneum has been wounded, inducing fatal peritonitis.
The operation, therefore, has been abandoned. Suprapubic cystotomy is considered above under
the heading of Surface Form. This operation may be employed to permit of the removal of a
calculus and is then called suprapubic lithotomy.
THE MALE URETHRA (URETHRA VIRILIS) (Figs. 1061, 1062, 1063, 1064, 1069).
The urethra in the male extends from the neck of the bladder at the internal
orifice of the urethra (orificium urethrae internum) to the meatus urinarius, the
external orifice of the urethra (orificium urethrae externum), at the end of the penis.
The internal orifice has been described (p. 1449). The urethra presents a double
curve in the flaccid state of the penis (Fig. 1069), but in the erect state of this
organ it forms only a single curve, the concavity of which is directed upward. Its
length varies from eight to nine inches; and it is divided into three portions, the
prostatic, membranous, and spongy, the structure and relations of which are essen-
tially different. Except during the passage of the urine or semen, the urethra is a
mere cleft or slit, transverse, T-shaped or crescentic (Fig. 1063), with its upper
and under surfaces in contact. At the meatus urinarius the slit is vertical, and
in the prostatic portion somewhat arched (Fig. 1063).
The First or Prostatic Portion (pars prostatica) (Figs. 1051, 1061, 1062, 1070,
and 1071). — The first or prostatic portion is the widest and most dilatable part of
the canal. It is between the internal orifice of the urethra and the superior layer
of the triangular ligament and is within the pelvic cavity. It passes between the
two lateral lobes of the prostate gland, from the base to the apex of the gland,
lying nearer its anterior than its posterior surface. The gland seems to completely
surround this portion of the urethra (Fig. 1068), but the glandular matter of the
gland does not (Fig. 1066). The gland is like a buckle open in front, and the open
part of the buckle is closed by the prostatic muscle. The prostatic urethra is
about an inch and a quarter in length; the form of the canal is spindle-shaped,
being wider in the middle than at either extremity, and narrowest below, where it
joins the membranous portion, Except during the passage of fluid, the canal is in
a collapsed state, the anterior wall resting upon the posterior wall (Fig. 1063), and
the mucous membrane exhibiting longitudinal folds. When distended, the largest
portion of the prostatic urethra has a diameter of about one-third of an inch.
THE MALE URETHRA
1451
A transverse section of the canal as it lies in the prostate is horseshoe-shaped,
the convexity being directed forward (Figs. 1063 and 1066). The direction of
the canal is nearly vertical, there being a slight curve, which is concave forward
(Figs. 1051 and 1052).
Upon the posterior wall or floor of the canal is a narrow longitudinal ridge, the
crest of the urethra (crista urethralis], formed by an elevation of the mucous mem-
brane and its subjacent tissue (Fig. 1061). This
crest begins at the uvula vesicae, and passes Crest of ^
through the prostatic portion and into the mem-
branous portion of the urethra (Fig. 1071), and
usually bifurcates at its distal end; it contains,
according to Kobelt, muscular and erectile tis-
sues. On this longitudinal ridge is an enlarge-
ment, the verumontanum or caput gallinaginis CowPer
(colliculus seminalis) (Figs. 1061 and 1071).
When distended, it may serve to prevent the
passage of the semen backward into the blad-
der. On each side of the verumontanum is a
slightly depressed fossa, the floor of which is
perforated by numerous apertures, the orifices
of the prostatic ducts (Figs. 1061 and 1071), from
the lateral lobes of the glands; the ducts of the
middle lobe open behind the verumontanum. ca
At the forepart of the verumontanum, in the
middle line, is a depression, the prostatic sinus,
prostatic utricle, prostatic vesicle, uterus mascu- Corpus
linus or sinus pocularis (utriculus prostaticus) spon
(Figs. 1052 and 1071); and upon or within its
margins are the slit-like openings of the ejacu-
latory ducts (ductus ejaculatorii) (Fig. 1071).
The sinus pocularis forms a cul-de-sac about a
quarter of an inch in length, which runs upward
and backward in the substance of the prostate
behind the transverse band of prostatic tissue
which joins the lateral lobes behind the poste-
rior wall of the urethra ; its prominent anterioi
wall partly forms the verumontanum. Its walls
are composed of fibrous tissue, muscular fibres,
and mucous membrane, and numerous small
glands open on its inner surface. It has been
called by Weber, who discovered it, the uterus
masculinus, from its being developed from the united lower ends of the atrophied
Miillerian ducts, and therefore being homologous with the uterus and vagina in the
female.
The Second, Muscular or Membranous Portion ( 'par 'smembranacea) (Figs. 1061,
1062, and 1071) extends downward and forward between the apex of the prostate
and the bulb of the corpus sppngiosum. It is the narrowest part of the canal(except-
ing the meatus), and measures three-quarters of an inch along its upper, and half
an inch along its lower, surface, in consequence of the bulb projecting backward
beneath it. Its anterior concave surface is placed about an inch below and behind
the pubic arch, from which it is separated by the dorsal vessels and nerves of the
penis, and some muscular fibres. Its posterior convex surface is separated from
the rectum by a triangular space, which constitutes the perineum. The membra-
nous portion of the urethra lies chiefly between the inferior and superior layers of
Glans. \™a"r .f^H// Fossa
Meatus.
FIG. 1061. — The male urethra, laid open on
its anterior (upper) surface. (Testut.)
1452
THE URINARY ORGANS
the triangular ligament (Fig. 308). The termination of this part of the urethra is
overlapped by the bulb, and is in front of the triangular ligament (Fig. 308). As it
pierces the inferior layer, the fibres around the opening are prolonged over the
tube and fix the two structures firmly to each other. The membranous urethra
is surrounded by cavernous tissue and by the Compressor urethrae muscle (m.
sphincter urethrae membranaceae) (Fig. 309). On the floor of the membranous
urethra is the anterior extremity of the crista urethralis. Behind this part of the
urethra, on each side of the middle line, are Cowper's glands (Figs. 307 and 1071).
The canal enters the bulb a little in front of the posterior extremity, and the an-
terior wall or roof of the membranous urethra is a little longer than the posterior
wall or floor. The backward projection of the bulb hangs over most of the floor
of the membranous urethra (Figs. 307, 308, 1061, 1071, and 1073). When the
urethra is empty the mucous membrane of the second part is thrown into longitu-
dinal folds, which are obliterated by distention.
MUSCULAR WALL
OF BLADDER'
PROSTATIC
SINUS
LONGITUDINAL MUS-
CLES OF URETHRA
FIG. 1062. — Proximal portions of urethra with surrounding parts. (After Testut.)
The Third, Penile, Pendulous, Cavernous or Spongy Portion (pars cavernosa)
(Figs. 1051, 1061, 1062, and 1064) is the longest part of the urethra, and is con-
tained in the corpus spongiosum. It is about six inches in length, and extends
from the termination of the membranous portion to the meatus urinarius. It is
surrounded throughout its entire course by the erectile tissue of the corpus spon-
giosum and glans penis. Its proximal end is fixed in position and unchangeable
in direction. Its distal end is movable and changeable in direction. Commencing
just below the triangular ligament it is first directed forward through the bulb;
it then passes downward and forward, the turn beginning at the seat of attachment
of the suspensory ligament of the penis (Fig. 1051). The direction of the third por-
tion of the urethra is changed by alterations in the position of the penis. When the
canal is closed the anterior and posterior walls are in contact (roof and floor), except
in the glans penis, where the lateral walls come together. " Thus the first part of
the canal when empty is represented in cross-section by a transverse slit, and the
terminal part by a vertical slit"1 (Fig. 1063). The calibre of the spongy urethra
varies in different portions of the tube. It is of larger diameter in the bulb (bul-
bous portion of urethra) and in the glans than between these two points. In the
1 Professor A. Francis Dixon, in Professor D. J. Cunningham's Text-book of Anatomy.
THE MALE URETHRA
1453
body of the penis the canal is of uniform size, and is about one-quarter of an inch
in diameter. The fossa navicularis (fossa navicularis urethrae [Morgagni]) is an
oblong dilatation of the terminal portion of the penile urethra (Figs. 1051, 1061,
and 1075). In the front of the fossa navicularis there is a transverse fold of
PROBE IN
/LACUNA MAQNA
QLANS
RlOHT LIP OF MEATUS
SKIN
SIDE OF URETHRA
LARGE LACUNA
SPONOY BODY — cut surface
MEDIAN LACUN/t
SPONQIOSUM
FIG. 1064. — The distal portion of the male urethra, laid open on its posterior
(under) surface, showing the lacunae. (Testut.)
mucous membrane, the valve of Guerin (valvulae fossae navicu-
laris). It is part of a distinct depression or pocket. The fossa
navicularis opens anteriorly by the meatus urinarius.
The meatus urinarius or external orifice of the urethra (orificium
urethrae externum) (Figs. 1061 and 1074) is the most con-
tracted part of the urethra; it is a vertical slit (Fig. 1063),
about three lines in length, bounded on each side by a small
lip or labium.
The inner surface of the lining membrane of the urethra,
especially on the floor of the spongy portion, presents the ori-
fices of numerous mucous glands (Fig. 1064) situated in the
submucous tissue, and named the glands of Littre (glandulae
urethrales}. A number of little recesses or follicles, called
lacunae (lacunae urethrales}, open into the penile urethra.
Some of the glands of Littre open into the lacunae; some do
not. They vary in size, and their orifices are directed forward,
FIG. 1063.— Cross-sec- ,, , ., J ., . . , ,, . , » ,, . . '
ms of the male urethra so that they may easily intercept the point ot a catheter in its
118 end?"Cshow?n^ passage along the canal. One of these lacunae, larger than
the rest, is situated in the upper surface of the fossa navicu-
laris, about half an inch from the orifice; it is called the
lacuna magna (Fig. 1075). Into the bulbous portion are found opening the ducts
of Cowper's glands.
Structure. — The urethra is composed of a continuous mucous membrane,
supported by a submucous tissue which connects it with the various structures
through which it passes.
The Mucous Coat. — The mucous coat forms part of the genito-urinary mucous
membrane. It is continuous with the mucous membrane of the bladder, ureters,
and kidneys; externally with the integument covering the glans penis; and is pro-
longed into the ducts of the glands which open into the urethra — viz., Cowper's
glands and prostate gland — into the vasa differentia and the seminal vesicles
through the ejaculatory ducts, The mucous membrane is arranged in longitudinal
marked alterations
form. (Testut.)
1454 THE URINARY ORGANS
folds when the tube is empty. Small papillae are found upon it near the orifice,
and its epithelial lining is of the columnar variety, excepting near the meatus,
where it is squamous.
The Glands and Crypts of the Urethral Mucous Membrane (Fig. 1063) . — There is q,
pocket, the lacuna magna (Fig. 1060) , opening to the front in the upper wall of the
fossa navicularis. The fossa is bounded by the valve of Guerin (valvidae fossa navic-
ularis) . The lacunae of Morgagni are in the spongy urethra back of the valve of
Guerin. The lacunae look forward. The largest of them is on the roof of the fossa
navicularis, one and one-half inches from the orifice (see above). Some of the
lacunae receive the secretion from the glands of Littre; others do not, because some
of the glands open on the free surface. The larger lacunae are one-third of an inch
deep and are placed in a longitudinal row upon the anterior wall. The smaller
lacunae are in longitudinal rows at the sides of the tube. The glands of Morgagni
are present throughout the urethra, except in its most anterior part. In the prostatic
urethra they are arranged in rows. In the membranous urethra they are scat-
tered irregularly. In the spongy portion they are most numerous on the anterior
wall and are more plentiful on the sides than on the floor. Besides the lacunae and
racemose glands, there are the opening of the prostatic glands, the ejaculatory
ducts, Cowper's glands, and the opening of the sinus pocularis.
The Submucous Tissue. — The submucous tissue consists of a vascular erectile
layer. It contains the glands of Littre, especially in the posterior part. These
glands are lined with cylindrical epithelium and enter the submucous coat.
The Muscular Layer. — The muscular layer is continuous with the muscle of the
prostate and bladder. It is composed of non-striated muscle arranged in an
outer layer of circular fibres (stratum circulars) and an inner layer of longitudinal
fibres (stratum longitud.inale). It is placed external to the submucous coat. In
the penile urethra there is only a thin layer of longitudinal fibres. In the mem-
branous urethra and the prostatic urethra there are two layers of muscle, an inner
thin layer of longitudinal fibres and a thicker layer of circular fibres. The longi-
tudinal fibres, when contracted, shorten the urethra and increase its diameter.
The circular fibres are in a state of tonic contraction and close the urethra. In
fact, they constitute the real sphincter (Zeissl, Zuckerkandl). -The so-called
sphincter of the urethra, the Accelerator urinae, is a voluntary muscle and is not
the real sphincter. Outside of the muscular layer of the urethra is the tissue
of the corpus spongiosum.
Surgical Anatomy. — The urethra may be ruptured by the patient falling astride of any hard
substance and striking his perinseum, so that the urethra is crushed against the pubic arch.
Bleeding will at once take place from the urethra, and this, together with the bruising in the
perinseum and the history of the accident, will at once point to the nature of the injury.
Rupture of the urethra leads to extravasation of urine. In rupture back of the superior layer
of the triangular ligament the urine usually follows the rectum and reaches the margin of the
anus. Rupture between the two layers of the triangular ligament liberates urine between the
two layers, where it remains until a path of exit is made by suppuration or the surgeon's knife.
In rupture in front of the anterior layer of the ligament the urine passes into the scrotum and
may mount up to the abdomen between the symphysis and the pubic spine, between which
points the deep layer of the superficial fascia is not attached. It cannot pass to the thigh nor
cross the mid-line, because the fascia is attached to the fascia lata and at the mid-line.
The surgical anatomy of the urethra is of considerable importance in connection with the
passage of instruments into the bladder. Otis was the first to point out that the urethra is
capable of great dilatation, so that, excepting through the external meatus, an instrument corre-
sponding to 18 English gauge (29 French) can usually be passed without damage. The orifice
of the urethra is not so dilatable, and therefore may require slitting, although the introduction
of the Oberlander dilator, which is expanded after introduction, renders slitting of the meatus
seldom necessary in cases of chronic gonorrhoea. A recognition of this dilatability caused Bige-
low to very considerably modify the operation of lithotrity and introduce that of litholapaxy.
In passing a fine catheter, the point of the instrument after it has passed the lacuna magna
should be kept as far as possible along the upper wall of the canal, as the point is otherwise
very liable to enter one of the lacunae. Stricture of the urethra is a disease of very common
THE MALE URETHRA 14.-).")
occurrence, and is generally situated in the spongy portion of the urethra, most commonly in
the bulbous portion, just in front of the membranous urethra, but in a very considerable num-
ber of cases in the penile or ante-scrotal part of the canal. Even in a normal urethra, and very
markedly in an inflamed urethra, a bougie encounters resistance behind the bulb. This is
usually supposed to be due to spasm of the Compressor urethrae muscle.
In irrigation of the urethra by gravity fluid tends to block at the same point, especially if it is
thrown in suddenly or forcibly. If a reservoir is raised seven and one-half feet from the floor,
and if a patient sits on a chair or lies upon a bed, fluid can be readily made to pass by hydraulic
pressure from the meatus to the bladder. Spasm may temporarily prevent the inflow, but the
weight of the column of fluid soon tires out the muscle and causes it to relax. Relaxation
is favored by having the patient take slow, deep breaths and make efforts at urination
(Valentine).
Chronic gonorrhoea is frequently kept up by persistent inflammation of the ducts and follicles in
the mucous membrane. This condition is known as chrome glandular urethritis or para-
itrrfhritix. In these crypts and glands gonococci may remain when gonorrhoea appears to have
passed away, and from time to time reinfection of the urethra may arise from such a source.
Median urethrotomy or perineal section is opening of the membranous urethra. Through such
an opening the bladder can be drained and explored, and the operation is sometimes called
median cystotomy.
In lateral lithotomy the knife enters the membranous urethra and strikes the groove of the
staff. Its edge is then turned toward the left ischial tuberosity and is carried along the groove
into the bladder, dividing the membranous urethra, the prostatic urethra, the posterior layer of
the triangular ligament, the Compressor urethrae muscle, anterior fibres of the Levator arii
muscle and the left lobe of the prostate gland.
THE FEMALE URINARY BLADDER.
The female bladder is situated at the anterior part of the pelvis. It is in relation, in
front, with the symphysis pubis ; behind, with the utero-vesical pouch of peritoneum,
which separates it from the body of the uterus; its base lies in contact with the
connective tissue in front of the cervix and upper part of the vagina. Laterally,
is the recto-vesical fascia. The bladder is said by some anatomists to be larger in
the female than in the male. At any rate, it does not rise above the symphysis
pubis till more distended than in the male, but this is perhaps owing to the more
capacious pelvis rather than to its being of actually larger size. It is described
in the section on the Bladder (p. 1441).
THE FEMALE URETHRA (URETHRA MULIEBRIS).
The female urethra is a narrow membranous canal, about an inch and a half in
length, extending from the internal urethral orifice (orificium urethrae internum)
at the neck of the bladder to the vestibule of the vagina, where it ends, being
called at its termination the external orifice of the urethra or the meatus urinarius
(orificium urethrae externum). The meatus is usually a vertical slit. The
urethra is placed behind the symphysis pubis, embedded in the anterior wall
of the vagina; and its direction is obliquely downward and forward, its course
being slightly curved, the concavity directed forward and upward. Its diameter
when undilated is about a quarter of an inch. The urethra perforates both
layers of the triangular ligament, and its external orifice is situated directly in
front of the vaginal opening and about an inch behind the glans clitoridis. Except
above, the posterior wall of the urethra is firmly connected to the anterior wall
of the vagina.
Structure. — The urethra consists of three coats: muscular, erectile, and mucous.
The Muscular Coat (tunica muscularis). — The muscular coat is continuous with
that of the bladder; it extends the whole length of the tube, and consists of an ,
internal layer of non-striated longitudinal fibres (stratum longitudinale) and an
external layer of non-striated circular fibres (stratum circulare). Superficial to the
circular fibres "lies a layer of cross-striped muscle-fibres, which form a closed ring
near the bladder only."1
1 Hand Atlas of Human Anatomy. By Prof. Werner Spalteholz. Translated and edited by Prof. Lewellys F
Barker.
1456
THE URINARY ORGANS
The Submucous Coat (tunica submucosa). — Internal to the muscular coat is the
submucous coat, which contains a venous plexus, networks from which pass
between the muscular layers and impart to these layers an erectile or spongy
nature (corpus spongiosum urethrae). In addition to this, between the two layers
of the triangular ligament, the female urethra is surrounded by the Compressor
urethrae muscle, as in the male.
INTERNAL
ORIFICE OF
URETHRA
RECTO-
UTERINE
POUCH
FOR NIX
OF VAGINA
RECTO-
VAGINAL
SEPTUM
EXTERNAL
ORIFICE OF
URETHRA
FIG. 1065.— Mesal section through the pelvis of a woman, aged cwenty-one years.
(Corning.)
Peritoneum in blue.
The Mucous Coat tunica mucosa) .—The mucous coat is pale, continuous exter-
nally with that of the vulva, and internally with that of the bladder. It is thrown
into longitudinal folds, one of which, placed along the floor of the canal, extends
from the vesical trigone almost to the external orifice of the urethra. It is called
the crest (crate urethralis). The outline of the urethra is stellate when collapsed,
because of the formation of numerous longitudinal folds. It is lined by laminated
epithelium, which becomes transitional near the bladder. Many mucous glands
open into the urethra, and there are numerous lacunae. External to the external
orifice, on each side, a group of mucous glands opens by a common duct, the
ductus para-urethralis.
The urethra, because it is not surrounded by dense resisting structures, as in the male, admits
of great dilatation, which enables the surgeon to remove with considerable facility calculi o:
other foreign bodies from the cavity of the bladder.
THE MALE ORGANS OF GENERATION.
THE PROSTATE GLAND (PROSTATA) (Figs. 1062, 1066, 1067, 1068, 1069,
1070, 1071, 1072).
PROSTATIC
MUSCLE
GLANDULAR
TISSUE
THE prostate gland (TipoiaTypc, to stand before) is a structure accessory to the
true generative organs and furnishes a viscid, opalescent secretion in which
spermatozoids will live (W. G. Richardson). It is a pale, firm, partly glandular
and partly muscular body, which is
placed immediately below the neck of the
bladder and about the commencement of
the urethra in the male. The prostate
appears to completely surround the first
portion of the urethra (Figs. 1068 and
1072), but the glandular matter does not
in reality completely surround the tube
(Figs. 1066 and 1072). As Spalteholz
says, it partly surrounds it as a broad
clasp, open in front. This opening ir. the
glandular tissue is closed, and a com-
plete ring is established about the urethra
by the prostatic muscle (m. prostaticus)
(Figs. 1066 and 1072). This muscle below is composed of striated fibres and
is continuous with the Compressor urethrae (m. sphincter urethrae membranacea) ;
MUSCULAR
LAYER OF
URETHRA
URETHRA
CJACULATORY
UTRICLE DUCT
FIG. 1066. — Section of the prostate. (Jarjavay.)
PROSTATIC
, MUSCLE
TRANSVERSE
PERINEAL LIGAMENT
FIG. 1067. — Side view of the position of the prostate. (Poirier and Charpy.)
above it is composed of non-striated muscle, and is continuous with the circular
muscular fibres of the bladder which surround the internal urethral orifice and
92 ( 1457 )
1458
THE MALE ORGANS OF GENERATION
constitute the Sphincter vesicae (Fig. 1067). The general course of the fibres is
transverse, with radiations into the gland substance. The apex of the gland for
about one-quarter of an inch is completely surrounded by the muscle (Fig. 1067).
VAS
DEFERENS
PROSTATE
FIG. 1068. — Prostate with seminal vesicles and seminal ducts, viewed from in front and above. (Spalteholz.)
Ascending from the apex the fibres cover for a short distance only the front of the
gland and are attached at the sides to the fascia (Fig. 1067). Higher up the muscle
AMPULLA
OF VAS
DEFERENS
VAS
DEFERENS
EJACULATORY
DUCT
PROSTATIC
UTRICLE
PROSTATE.
GLAND
COWPEFT
GLAND
PERITONEUM
CORPUS
SPONGIOSUM
CORPUS
CAVERNOSUM
HYDATID OF
MORGAGNI
FIG. 1069. — Diagrammatic representation of the male reproduction organs and their relations to the bladder
and the urethra. Lateral view. (Toldt.)
passes between the sheath and the capsule and ascends to the base of the prostate,
uniting the sheath to the capsule along the mid-line in front. The prostate is placed
in the pelvic cavity, behind the lower part of the symphysis pubis, and above the
THE PROSTATE GLAND
1459
deep layer of the triangular ligament, and rests upon the rectum, through which
it may be distinctly felt, especially when enlarged (Fig. 1070).
The ejaculatory ducts (Figs. 1068, 1069, and 1070) enter the prostate at the margin
which separates the base fro'm the posterior surface of the gland ; they pass down-
ward, inward, and forward through the prostate, and open into the prostatic
urethra. The prostate when surrounded by its sheath resembles a chestnut in
shape. When dissected out from its sheath and capsule and from the Prostatic
muscle, it resembles an "open clasp" or horseshoe. The sheath of the prostate
LEFT COMMON
ILIAC VEIN
FIG. 1070. — Sagittal section of the lower part of a male trunk, the right segment. (Testut.)
is derived from the recto- vesical fascia. It is called the prostatic fascia (fascia pro-
statae), is distinct and dense, and covers the entire prostate, except at the apex and
at the attachment of the base of the prostate to the neck of the bladder. The pros-
tatic fascia is a distinct structure, though it is thin. The veins of the prostatic
plexus lie in the layers of the sheath, "and are everywhere separated from the
prostatic capsule proper by a layer of this sheath."1 In an enlarged prostate
the sheath is thick and fibrous. It is very difficult to shell out a normal prostate
from its sheath, but it is easy to shell out an enlarged prostate. Within the pros-
tatic sheath (which, be it remembered, carries the veins) is the true or proper capsule
1 J. W. Thomson Walker, in the British Medical Journal, July 9, 1904.
H60
THE MALE ORGANS OF GENERATION
of the prostate. The true capsule is a continuous investment from the entrance
of the urethra above to the triangular ligament below. It is thin, but firm and
fibrous. It is not everywhere absolutely distinct from the sheath, but may be fused
MOUTH OF EJACU-_..gl=,]
LATORY DUCT
VERUMONTANUM- —
OPENINGS OF
PHOSTATIC DUCTS
MEMBRANOUS URETHRA
OUT SURFACE
DUCT OF COWPER'S
GLAND— LAID BARE
A RIDGE OF
MUCOSA
BULBOUS
URETHRA
CORPUS SPON-
GIOSUM — CUT SURFACE
FIG. 1071. — Proximal portion of the urethra, laid open by a median, anterior cut. (Testut.)
I
FIG. 1072. — Transverse section of normal prostate through the middle of the verumontanum, from a subject
aged nineteen years: a, longitudinal section of ducts leading from the lobules of the prostatic glands ; b, veru-
montanum ; c, sinus pocularis ; d, urethra ; e, ejaculatpry ducts ; /, arteries, veins, and venous sinuses in sheath
of prostate ; g, nerve trunks in sheath ; h, point of origin of fibro-muscular bands encircling urethra ; i, zone of
striated voluntary muscle on superior surface. (Drawn from Erdinger projection apparatus.) (Taylor.)
THE PROSTATE GLAND 1401
with it here and there, and many bands of fibres run from the sheath to the capsule.1
The capsule is continuous with the stroma of the giand and cannot be stripped off as
can the kidney capsule. Any attempt to strip off the capsule tears away fragments
of gland. The capsule is composed of fibrous tissue and unstriated muscle-fibres.
From its deep surface the capsule is continuous with the stroma of the prostate ( W. G.
Richardson). Sir Henry Thompson, half a century ago, pointed out the distinction
between true capsule and sheath, and suggested these names. The prostate is divided
for study into a base, apex, posterior surface, anterior surface, and lateral surfaces.
The Base (basis prostatae}. — The base is directed upward, and is situated
immediately below the base of the bladder. It is in contact with and supports the
base of the bladder. The external longitudinal muscular layer of the bladder is
attached to the posterior portion of the base of the prostate, and some of the fibres
reach and adhere to the true capsule. The anterior portion of the base is called
the isthmus (isthmus prostatae) (Fig. 1068).
The Apex (apex prostatae). — The apex is directed downward and rests upon
the deep layer of the triangular ligament. The apex is fixed, except for the slight
mobility of the triangular ligament ; the rest of the gland is somewhat movable.
Surfaces. — The Posterior Surface (fades posterior). — The posterior surface is
flattened, marked by a slight longitudinal furrow, and rests on the second part of
the rectum, and is distant about one inch and a half from the anus. At the upper
and posterior border of the gland are the seminal vesicles. Their direction is
downward and inward; in fact, almost transverse.
The Anterior Surface (fades anterior). — The anterior surface is convex, and placed
about three-fourths of an inch behind the pubic symphysis,from which it is separated
by a plexus of veins and a quantity of loose fat. It is connected to the pubic bone
on either side by the pubo-pro static ligament. It is shorter than the posterior surface.
The Lateral Surfaces. — The lateral surfaces are prominent, and are covered by
the anterior portions of the Levatores ani muscles, which are, however, separated
from the gland by a plexus of veins.
The prostate measures about an inch and a half transversely at the base, an
inch in its antero-posterior diameter, and an inch and a quarter in its vertical
diameter. Its weight is about four and a half drachms. It is held in position
by the anterior ligaments of the bladder (ligamenta puboprostatica) ; by the deep
layer of the triangular ligament, which invests the commencement of the mem-
branous portion of the urethra and prostate gland ; and by the anterior portions of
the Levatores ani muscles, which pass backward from the os pubis and embrace
the sides of the prostate. These portions of the Levatores ani, from the support
they afford to the prostate, are named the Levator prostatae.
The prostate consists of two lateral lobes and a middle lobe.
The Lateral Lobes (lobus dexter et sinister). — The two lateral lobes are of
equal size, separated by a deep notch above, and by a furrow upon the anterior
and posterior surfaces of the gland, which indicates the bilobed condition of the
organ in some animals. At the upper and posterior portion of the prostate the
two lobes are united by two bands of gland -tissue. One of these bands is in front
of the ejaculatory ducts, the other is below them. "The upper limit of the gland
is thus in the form of a horseshoe, open in front."2 Below the level of the prostatic
ducts the prostate and urethra are in relation, but are not closely connected.
Above this level the connection is intimate (J. W. Thomson Walker).
The So-called Middle Lobe (lobus medius). — The middle lobe is not in reality a
lobe, and the name is usually employed to describe an enlargement of the region of
the prostate on the posterior portion of the urethra in front of the ejaculatory ducts.
The so-called third or middle lobe is an abnormal condition. It is due to enlargement
of the transverse band of prostatic tissue which joins the lateral lobes beneath the
1 W. G. Richardson on the Development and Anatomy of the Prostate Gland.
2 J. W. Thomson Walker, in the British Medical Journal, July 9, 1904.
1462 THE MALE ORGANS OF GENERATION
base of the bladder, behind the posterior wall of the urethra and in front of the ejacu-
latory ducts. This mass of tissue is beneath the uvula vesicae. Walker points out
that frequently nodules of enlarged prostate protrude into the bladder,being covered
only by bladder mucous membrane. This is accomplished by the enlarging pros-
tate forcing its way through the lumen of the vesical sphincter and dilating it,
and separating and passing between the strands of the internal longitudinal
muscle of the bladder. "The so-called middle lobe is formed by the protrusion of
a nodule between the two bands of muscle which pass into the trigorie from the
ureters, and unite on the posterior wall of the prostatic urethra."1
The urethra passes forward between the lateral lobes of the prostate. The
prostate is perforated by the ejaculatory ducts. The urethra usually lies on the
level of the junction of the anterior and middle thirds of a lateral lobe. The
ejaculatory ducts pass obliquely downward and forward through the posterior
part of the prostate, and open into the prostatic portion of the urethra.
Structure (Fig. 1072). — As previously stated (p. 1459), the prostate is surrounded
by a sheath from the recto-vesical fascia, and possesses also a true capsule.
The glands of the prostate are of the branched tubular variety and number
forty or fifty. Many of the ducts join and form from fifteen to twenty-five smaller
ducts, which empty into the prostatic urethra, to the sides of the verumontanum
(Fig. 1071). The ducts and glands are lined with cubical epithelium. The
prostatic secretion or prostatic fluid (succus prostaticus) is a viscid, opalescent,
serous secretion, alkaline in reaction, containing a ferment, but no mucus. The
substance of the prostate is of a pale, reddish-gray color, of great density and
not easily torn. It consists of glandular substance and muscular tissue.
The muscular tissue, according to Kolliker, constitutes the proper stroma of
the prostate, the connective tissue being very scanty, and simply forming thin
trabeculae between the muscular fibres, in which the vessels and nerves of the
gland ramify. The true capsule is continuous with the stroma. The stroma lies
between the glandular substance and strands of stroma pass in convergent lines
toward the prostatic urethra, especially toward the dorsum of the urethra. These
strands or septa divide the prostate into small irregular subdivisions called lobules.
Next to the urethra, the stroma forms a thick layer. As age advances the inter-
stitial tissue of the prostate increases and the glandular substance shrinks.
Vessels and Nerves. — The arteries supplying the prostate are derived from the
internal pudic, inferior vesical, and middle haemorrhoidal. Branches of the vessels
enter the gland in the septa between the lobules and send off minute branches to the
lobules (Walker). The veins form a plexus around the sides and base of the gland
between layers of the fascial sheath; they receive in front the dorsal vein ot the
penis, and terminate in the internal iliac vein. The lymphatics of the prostate
begin as networks about the acini of the gland, pass to beneath the capsule, and
form another network, and from this peripheral network collecting trunks arise.
Several trunks pass from the posterior portion of the gland. One trunk passes to
the external iliac glands, one to the internal iliac glands, and several end in the
lateral sacral glands, and the glands of the sacral promontory. An anterior trunk
is joined by lymphatics from the membranous urethra and prostatic urethra and
passes to a gland on the internal pudic artery.2 The nerves are derived from the
hypogastric plexus.
Surgical Anatomy. — The relation of the prostate to the rectum should be noted: by means of
the finger introduced into the gut the surgeon detects enlargement or other disease of the prostate;
he can feel the apex of the gland, which is the guide to Cock's operation for stricture; he is enabled
also by the same means to direct the point of a catheter when its introduction is attended with
difficulty either from injury or disease of the membranous or prostatic portions of the urethra.
When the finger is introduced into the bowel the surgeon may, in some cases, especially in boys,
1 J. W. Thomson Walker, in the British Medical Journal, July 9, 1904.
2 Poirier and Charpy. Human Anatomy.
THE PENIS 1463
learn the position, as well as the size and weight, of a calculus in the bladder. In the operation
for the removal of a calculus, if, as is not (infrequently the case, the storie should be lodged
behind an enlarged prostate, it may be displaced from its position by pressing upward the base
of the bladder from the rectum. The prostate gland is occasionally the seat of suppuration, either
due to injury, gonorrhoea, or tuberculous disease. The gland is enveloped in a dense unyield-
ing capsule, which determines the course of an abscess, and also explains the great pain which is
present in acute inflammation. The abscess most frequently bursts into the urethra, the direc-
tion in which there is least resistance, but may occasionally burst into the rectum, or more rarely
in the perinseum. In advanced life the prostate often becomes considerably enlarged, and may
project into the bladder so as to impede the passage of the urine. According to Dr. Messer's
researches, conducted at Greenwich Hospital, it would seem that such obstruction exists in 20
per cent, of all men over sixty years of age. The prostate may be enlarged by the growth of
innocent tumors, adenomata, fibromata, myomata, and myofibromata. The entire gland may
be hypertrophied. A tumor may be encapsulated, but often is surrounded by an area of hyper-
plasia of prostatic tissues, and usually the area of hyperplasia is much more extensive than the
tumor. A tumor may be beneath the mucous membrane, deep in the gland, or beneath the
sheath. The growth called the third lobe is submucous. In some cases the enlargement affects
principally the lateral lobes, which may undergo considerable enlargement without causing much
inconvenience. In other cases it would seem that the nodule forms the so-called middle lobe,
and even a small enlargement of this character may act injuriously, by forming a sort of valve
over the urethral orifice, preventing the passage of the urine, and the more the patient strains,
the more completely will it block the opening into the urethra. In consequence of the enlarge-
ment of the prostate a pouch is formed at the base of the bladder behind the projection, in which
urine collects and cannot entirely be expelled. The urine becomes decomposed and ammoniacal,
and leads to cystitis. If the prostate enlarges the urethra is lengthened, often dilated, altered
in shape, or distorted.
The relation of the enlarged prostate to the neck of the bladder is greatly altered from the
relation of the normal prostate. Normally, it is extra vesical ; when enlarged it may encapsule
"the neck of the bladder in a cuff-like manner, extending several inches upward on its wall,"
and often it protrudes "into the vesical cavity, carrying on its surface the mucosa vesicae."1 In
many cases of prostatic enlargement the gland should be removed (prostatectomy). One method
is enucleation through a suprapubic incision; another method is enucleation through a perineal
incision; another method is carried out by both incisions (the combined method).
The Bottini operation is prostatotomy, effected by a special instrument for the purpose of
cauterizing the gland and thus causing shrinking.
In elderly individuals the gland tubules may form round, indurated, and sometimes calcified
masses, about 1 mm. in diameter, and called prostatic stones.
COWPER'S GLANDS (GLANDULAE BULBO-URETHRALES)
(Figs. 1071, 1078).
Cowper's glands are two small, rounded, and somewhat lobulated bodies of
a yellow color, about the size of peas, placed behind the forepart of the mem-
branous portion of the urethra, between the two layers of the triangular ligament.
They lie close above the bulb, and are enclosed by the transverse fibres of the
Compressor urethrae muscle. Their existence is said to be constant, they gradually
diminish in size as age advances.
Structure. — Each gland consists of several lobules held together by a fibrous
investment. Each lobule consists of a number of acini lined by columnar epithe-
lial cells, opening into one duct, which, joining with the ducts of other lobules
outside the gland, form a single excretory duct (ductus excretorius] . The excretory
duct of each gland, nearly an inch in length, passes obliquely forward beneath
the mucous membrane, and opens by a minute orifice on the floor of the bulbous
portion of the urethra.
THE PENIS (Figs. 1073, 1074, 1075, 1076, 1077, 1078).
The penis is a long body of prismatic shape placed below and in front of the
symphysis pubis. It surrounds the greatest length of the urethra. It consists
of a root, body, and extremity or glans penis. The root and the posterior portion
1 John B. Murphy, in the Journal of the American Medical Association, May 28, 1904.
1464
THE MALE ORGANS OF GENERATION
of the body lie beneath the scrotum and the integument of the perinseum (Fig.
1069), and are firmly fixed to the triangular ligament, the pubic bones, and the
symphysis; hence this portion of the organ
is called the fixed portion (pars fixa) (Fig.
309). The balance of the organ is free
FOSSA OF
FRAENUM
PREPUCE
RETRACTED
MEDIAN GROOVE
NECK
DISTAL PART OF SEP-
TUM PECTINIFORME'
FIG. 1073. — The penis, proximal portion, seen
from below. (Testut.) FIG. 1074. — Glans penis, under surface. (Testut.)
and movable (Fig. 1069), and is called the mobile portion (pars mobilis). When
the penis is relaxed there is an angle between the fixed and mobile portions;
when the penis is erect, the angle disappears.
The Root (radix penis). — The root is firmly connected to the rami of the os
pubis and ischium by two strong tapering, fibrous processes, the crura (Figs. 1073,
1077, and 1078), and to the front of the symphysis pubis by the suspensory liga-
ment (Fig. 1076), a strong band
of fibrous tissue which passes
downward from the front of
the symphysis pubis to the root
of the penis.
The extremity, acorn, or
glans penis (Figs. 1074 and
1075) presents the form of an
obtuse cone, flattened from
above downward. At its sum-
mit is a vertical fissure, the
external orifice of the urethra or
the meatus urinarius (onficium
urethrae externum). The base
of the glans forms a rounded
projecting border, the corona
glandis, and behind the corona
is a deep constriction, the cer-
vix or neck (collum glandis).
Upon both the corona and neck
small sebaceous
glands are found, the glandulae
Tysonii odoriferae.1 They secrete a sebaceous matter of very peculiar odor,
which probably contains casein and becomes easilv decomposed.
PREPUCE
RETRACTED
FOSSA NAVIC-
ULARIS
'• FRENUM
_VALVE OF LA-
CUNA MAGNA
LEFT SIDE OF URETHRA
•••FLOOR OF URETHRA
LACUNA MAGNA
CORPUS
CAVERNOSUM CORPUS
SPONGIOSUM
FIG. 1075. — The penis, distal end, in sagittal section one-twelfth inch numerous
at left of middle line. (Testut.)
1 Stieda (Comptes-rendus du XII. Congres International de Medecine, Moscow, 1897) asserts that Tyson's
glands are never found on the corona glandis, and that what have hitherto been mistaken for glands are really
large papillae. — ED of 15th English edition. '
THE PENIS
1465
The Body of the Penis (corpus penis). — The body of the penis is the part
between the root and extremity. In the flaccid condition of the organ it is cylin-
drical, but when erect it has a triangular prismatic form with rounded angles, the
broadest side being turned upward, and called the dorsum penL>. The lower sur-
face of the body of the penis is called the urethral surface (fades urethralis). The
body is covered by integument, and contains in its interior a large portion of the
urethra. The integument covering the penis is remarkable for its thinness, its
dark color, its looseness of connection with the deeper parts of the organ, and for
the absence of adipose tissue. At the root of the penis the integument is contin-
uous with that upon the pubes and scrotum, and at the neck of the glans it leaves
the surface and becomes folded upon itself to form the prepuce (praeputium) (Fig.
1074). The internal layer of the prepuce is attached behind to the cervix or neck
(Fig. 1074), and approaches in character to a mucous membrane; from the cervix
it is reflected over the glans penis, and at the meatus urinarius is continuous with
the mucous lining of the urethra.
The integument covering the glans penis contains no sebaceous glands, but
projecting from its free surface are a number of small, highly sensitive papillae.
SUPERFICIAL
FIBRES OF
SUSPENSORY
LIGAMENT
DEEP FIBRES
OF SUSPENSORY
LIGAMENT
DORSAL VEIN
DORSAL ARTERY
DORSAL NERVE
PERITONEUM
ANTERIOR
LIGAMENT
OF BLADDER
SUBPUBIC
LIGAMENT
ERECTA PENIS
MUSCLE
FIG. 1076. — The suspensory ligament. (Poirier and Charpy.)
At the back part of the meatus urinarius a fold of mucous membrane passes
backward to the bottom of a depressed raphe, where it is continuous with the
prepuce ; this fold is termed the fraenum (frenulum praeputii). The skin of the penis
covers the mobile parts of the organ. It is thin, extremely elastic, and contains very
few hairs. Beneath the skin of the penis is the dartos layer (Figs. 1076 and 1083),
continuous with the scrotal dartos, containing chiefly non-striated muscular fibres
arranged longitudinally. It passes forward to the orifice of the prepuce, and
then turns backward, growing thinner and thinner, and finally disappearing at
the cervix. Beneath the dartos and extending forward to the orifice of the pre-
puce is a sheath of areolar tissue. It is a lax sheath rich in elastic tissue and
containing almost no fat. The superficial vessels and nerves are in the areolar
sheath. Beneath the areolar sheath of the penis, from the corona to the root, is
the fascia of the penis (fascia penis) (Fig. 1083). It covers the organ from the root
to the corona, and also covers the dorsal artery, veins, and nerves. It is continuous
behind with the superficial perineal fascia and suspensory ligament. It is com-
posed chiefly of elastic tissue.
Structure of the Penis. — The penis is composed of a mass of erectile tissue
enclosed in three cylindrical fibrous compartments. Of these, two, the corpora
1466
THE MALE ORGANS OF GENERATION
cavernosa, are placed side by side along the upper part of the organ; the third, or
corpus spongiosum, encloses the urethra and is placed below.
The Two Corpora Cavernosa (corpora cavernosa penis) (Figs. 1077 and 1078). — The
two corpora cavernosa form the chief part of the body of the penis. They consist of
two fibrous cylindrical tubes, placed side by side, and intimately connected along
the median line for their anterior three-
fourths, whilst at their back part they
separate from each other to form the
crura penis, which are two strong taper-
ing fibrous processes or roots firmly
connected to the rami of the os pubis
and ischium (Figs. 1073, 1077, and
1078). Each cms commences by a
VAS
DEFERENS
CORONA.
GLANDIS
CORONA
GLANDIS
EXTERNAL ORIFICE
OF URETHRA
FIG. 1077. — The penis, with the puhic bones, seen
from before and below. (Toldt.)
FIG. 1078. — The penis, with the urethra, Cowper a
glands, the prostate gland, and the seminal vesicles,
seen from below and behind. (Toldt).
THE PENIS
1467
blunt-pointed process in front of the tuberosity of the ischium, and before its junc-
tion with its fellow to form the body of the penis it presents a slight enlargement,
named by Kobelt the bulb of the corpus cavernosum. Just beyond this point they
become constricted, and retain an equal diameter to their anterior extremity, where
they form a single rounded end which is received into a fossa in the base of the glans
penis (Figs. 1075 and 1077). A median groove on the upper surface lodges the
dorsal arteries, nerves, and veins of the penis (Figs. 1081, 1082, and 1083), and the
groove on the under surface receives the corpus spongiosum (Fig. 1077). The
root of the penis is connected to the symphysis pubis by the suspensory ligament.
Structure (Fig. 1083). — Each corpus cavernosum is composed of erectile tissue.
The erectile tissue is surrounded by a strong fibrous envelope, the tunica albuginea,
corporum cavernosum, consisting of two sets of fibres — the one, longitudinal in direc-
tion, being common to the two corpora cavernosa, and investing them in a com-
mon covering; the other, internal, circular in direction, and being proper to each
corpus cavernosum. The internal circular fibres of the two corpora cavernosa
form, by their junction in the mesial plane, an incomplete partition or septum,
the septum penis, between the two bodies.
SUSPENSORY
LIGAMENT
FIG. 1079. —The clartos. (Poirier and Charpy.)
FIG. 1080. — From the peripheral portion of the corpus
cavernosum penis under a low magnifying power. 1, a,
capillary network; b, cavernous spaces; 2, connection of
the arterial twigs (a) with the cavernous spaces. (Copied
from Langer.)
The septum between the two corpora cavernosa is thick and complete behind,
but in front it is incomplete, and consists of a number of vertical bands, which are
arranged like the teeth of a comb, whence the name which it has received, septum
pectiniforme. These bands extend between the dorsal and the urethral surface
of the corpora cavernosa. The fibrous -in vestment of the corpora cavernosa is
extremely dense, of considerable thickness, and consists of bundles of shining
white fibres, with an admixture of well-developed elastic fibres, so that it is pos-
sessed of great elasticity.
From the internal surface of the fibrous envelope, as well as from the sides of
the septum, are given off a number of bands or cords which cross the interior of
each crus in all directions, subdividing it into a number of separate compart-
1468 THE MALE ORGANS OF GENERATION
merits, and giving the entire structure a spongy appearance. These bands and
cords are called trabeculae corponim cavernosum, and consist of white fibrous
tissue, elastic fibres, and plain muscular fibres. In them are continued numer-
ous arteries and nerves.
The component fibres of which the trabeculae are composed are larger and
stronger around the circumference than at the centre of the corpora cavernosa;
they are also thicker behind than in front. The interspaces, on the contrary, are
larger at the centre than at the circumference, their long diameter being directed
transversely; they are largest anteriorly. They are called cavernous spaces and
are occupied by venous blood, and are lined by a layer of flattened cells similar
to the endothelial lining of veins (Fig. 1080).
The whole of the structure of the corpora cavernosa contained within the
fibrous sheath consists, therefore, of a sponge-like tissue the areolar spaces of
which freely communicate with each other and are filled with venous blood.
The spaces may therefore be regarded as large cavernous veins.
The arteries bringing the blood to these spaces are the arteries of the corpora
cavernosa and branches from the dorsal artery of the penis, which perforate the
fibrous capsule, along the upper surface, especially near the forepart of the organ.
These arteries on entering the cavernous structure divide into branches which
are supported and enclosed by the trabeculae. Some of these terminate in a
capillary network, the branches of which open directly into the cavernous spaces
(Fig. 1080); others assume a tendril-like appearance, and form convoluted and
somewhat dilated vessels, which were named by Mtiller helicine arteries (arteriae
helicinae). They project into the spaces, and from them are given off small
capillary branches to supply the trabecular structure. They are bound down in
the spaces by fine fibrous processes, and are more abundant in the back part of the
corpora cavernosa.
The blood from the cavernous spaces is returned by a series of vessels, some of
which emerge in considerable numbers from the base of the glans penis and con-
verge on the dorsum of the organ to form the deep dorsal vein ; others pass out on the
upper surface of the corpora cavernosa and join the dorsal vein; some emerge from
the under surface of the corpora cavernosa, and, receiving branches from the corpus
spongiosum, wind around the sides of the penis to terminate in the dorsal vein;
but the greater number pass out at the root of the penis and join the prostatic plexus.
The Corpus Spongiosum (corpus cavernosum urethrae) (Figs. 1075, 1077, and
1078). — The corpus spongiosum encloses the urethra, and is situated in the groove
on the under surface of the corpora cavernosa penis. It commences posteriorly
below the superficial layer of the triangular ligament of the urethra, between
the diverging crura of the corpora cavernosa, where it forms a rounded enlarge-
ment, the bulb of the urethra, and terminates anteriorly in another expansion, the
glans penis (Figs. 1074, 1075, 1077, and 1078), which overlaps the anterior rounded
extremity of the corpora cavernosa. The central portion, or body of the corpus
spongiosum, is cylindrical, and tapers slightly from behind forward.
The Bulb of the Urethra (bulbus urethrae') (Figs. 1073, 1077, and 1078) varies
in size in different subjects; it receives a fibrous investment from the superficial
layer of the triangular ligament, and is surrounded by the Accelerator urinae mus-
cle. The urethra enters the bulb nearer its upper than its lower surface, being sur-
rounded by a layer of erectile tissue, a thin prolongation of which is continued
backward around the membranous and prostatic portions of the canal to the neck
of the bladder, lying between the two layers of muscular tissue. The portion of the
bulb below the urethra presents a partial division into two lobes (hemisphaeria
bulbi urethrae), being marked externally by a linear raphe, whilst internally there
projects, for a short distance, a thin fibrous median septum (septum bulbi urethrae),
which is more distinct in early life.
THE PENIS
1469
Structure. — The corpus spongiosum consists of a strong fibrous envelope
enclosing a trabecular structure, which contains in its meshes erectile tissue. The
fibrous envelope is thinner, whiter in color, and more elastic than that of the corpora
CAVERNOUS
BRANCH
DORSAL ARTERY
CORPUS CAVERNOSUM
CLANS PENIS
SN
INTERNAL PUDIC
ARTERY
FIG. 1081. — Diagram of the arteries of the penis. (Testut.)
cavernosa of the penis. The trabeculae are more delicate, more nearly uniform
in size, and the meshes between them smaller than in the corpora cavernosa,
their long diameter, for the most part, corresponding with that of the penis.
The external envelope or outer coat of the corpus spongiosum is formed partly
of unstriped muscular fibre, and a
layer of the same tissue immediately
surrounds the canal of the urethra.
Ligaments of the Penis. — The sus-
pensory ligament (ligamentum sus-
pensorium penis} (Fig. 1076) is firm
and fibrous. It passes from the front
of the symphysis pubis to the tunica
albuguinea of the corpora cavernosa.
The ligamentum fundiforme penis
(Fig. 1073), formerly called the sus-
pensory ligament, arises from the
linea alba, sheath of the rectus,
superficial fascia, and symphysis
pubis, and surrounds the penis in
a loop, being attached more distal-
ward than is the suspensory liga-
ment, and usually passes into the
scrotum. It is composed of elastic
tissue.
Vessels and Nerves of the Penis. —
The arteries (Fig. 1081) of the penis
come from branches of the internal
pudic artery. The deep arteries of
the penis give the chief supply to
the erectile tissue of the corpora
cavernosa, and the dorsal artery also
sends branches to it ; the artery of
the bulb (p. 693) supplies the erectile
tissue of the corpus spongiosum. The chief blood-supply of the glans is from
the dorsal artery (p. 694). In the trabeculae the arteries are very small and often
twisted. The twisted vessels are called helicine arteries. The small arteries
open directly into the venous spaces. The veins of the penis empty directly into
SUPERFICIAL DORSAL VEIN
EXTERNAL PUDIC VEIN
OBTURATOR VEIN
FIG. 1082.— Veins of the penis. (Testut.)
1470 THE MALE ORGANS OF GENERATION
the prostatic plexus or into the deep dorsal vein, which empties into the prostatic
plexus. On each side of the deep dorsal vein is a dorsal artery and external
to each dorsal artery is a dorsal nerve (Fig. 1083). The superficial dorsal vein
(Figs. 1082 and 1083), receiving small veins from the prepuce, passes back
beneath the skin, reaches the symphysis and divides into two branches, each of
which passes to the corresponding superficial external pudic vein.
The lymphatics of this region have been studied carefully by Poirier, Cuneo,
and Delamare,1 which book I have freely used.
The lymphatics of the skin of the penis and prepuce are continuous (Fig. 499).
Those on the internal surface of the prepuce are continuous with those of the glans.
The trunks of the cutaneous lymphatics anastomose with each other, ascend by
the dorsal vein, and terminate in the inguinal glands. The trunks 'from the glans
converge toward the frsenum ; they
SUPERFICIAL DOR- ,, i , ,, i. >
SAL VEIN then ascend to the median part of
DEEP
FASCIA
sides unite. Several collectors as-
cend on the dorsum to the inguinal
and femoral glands.
The superior wall of the anterior
portion of the urethra is drained by
the lymphatic trunks from the glans.
From the rest of the penile urethra
3ULBO-CAVERNOUS ARTERY/~~-~LJ ^ il 1 1 j.' ' ± ' i.\ J.1 1
-ANTERIOR BRANCH j URETHRA the lymphatics unite with the trunks
spoNoioluM from the penis, and most of them ter-
FIG. 1083.— The penis in transverse section, showing ininate ill the Same Way, although
the blood-vessels. (Testut.) „ . . J
one of them passes between the
Recti muscles and terminates in the deeper external iliac glands or in the
"internal retro-crural gland."2
The trunks from the bulb and membranous urethra terminate in the external
iliac glands, the "internal retro-crural gland," and the glands along the internal
pudic artery (Poirier, Cuneo, and Delamare). The trunks from the prostatic
urethra join the trunks from the prostate gland.
The nerves are derived from the internal pudic nerve and the pelvic plexus. On
the glans and bulb some filaments of the cutaneous nerves have Pacinian bodies
connected with them, and, according to Krause, many of them terminate in a
peculiar form of end-bulb.
Surgical Anatomy. — It is occasionally necessary to remove a penis for malignant disease.
Usually, removal of the ante-scrotal portion is all that is necessary, but sometimes it is requisite
to remove the whole organ from its attachment to the rami of the ossa pubis and ischia. The
former operation is performed either by cutting off the whole of the anterior part of the penis
with one sweep of the knife, or, what is better, cutting through the corpora cavernosa from the
dorsum, and then separating the corpus spongiosum from them, dividing it at a level nearer the
glans penis. The mucous membrane of the urethra is then slit up, and the edges of the flap
attached to the external skin, in order to prevent contraction of the orifice, which would other-
wise take place. The vessels which require ligature are the two dorsal arteries of the penis, the
arteries of the corpora cavernosa, and the artery of the septum. When the entire organ requires
removal the patient is placed in the lithotomy position, and an incision is made through the
skin and subcutaneous tissue around the root of the penis, and carried down the median line of
the scrotum as far as the perinseum. The two halves of the scrotum are then separated from
each other, and a catheter having been introduced into the bladder as a guide, the spongy por-
tion of the urethra below the triangular ligament is separated from the corpora cavernosa and
divided, the catheter having been withdrawn just behind the bulb. The suspensory ligament
is now severed, and the crura separated from the bone with a periosteum scraper, and the whole
penis removed. The membranous portion of the urethra, which has not been removed, is now
to be attached to the skin at the posterior extremity of the incision in the perinseum. The
remainder of the wound is to be brought together, free drainage being provided for.
1 The Lymphatics. By Poirier, Cune'o, and Delamare. Translated and edited by Cecil H. Leaf.
2 Ibid.
DESCENT OF THE TESTIS
1471
THE TESTICLES (TESTES) AND THEIR COVERINGS (Figs. 1086, 1087).
The testicles are two glandular organs, which secrete the semen; they are situ-
ated in the scrotum, being suspended by the spermatic cords. At an early period
of foetal life the testes are contained in the abdominal cavity, behind the peri-
toneum, but they subsequently descend into the scrotum.
DESCENT OF THE TESTIS (DESCENDUS TESTIS).
Each testis at an early period of foetal life is placed at the back part of the
abdominal cavity, behind the peritoneum, in front and a little below the kidney.
The anterior surface and sides are invested by peritoneum. At about the third
month of intra-uterine life a peculiar structure, the gubernaculum testis, makes its
appearance. This structure is at first a slender band which extends from the
situation of the internal ring to the epididymis and body of the testicle, and is
then continued upward in front of the kidney toward the Diaphragm. As devel-
opment advances the peritoneum covering the testicle encloses it and forms a
mesentery, the mesorchium, which also encloses the gubernaculum and forms two
folds — one above the testicle, and the other below it. The one above the testicle is
CREMASTER
ANASTOMOSIS
OF VEINS
FIG. 1084. — Vaginal tunics of the testicle.
(Poirier and Charpy.)
FIG. 1085. — Ligament of the scrotum.
(Poirier and Charpy.)
the plica vascularis, and contains ultimately the spermatic vessels; the one below,
the plica gubernatrix, contains the lower part of the gubernaculum, which has now
grown into a thick cord ; it terminates below at the internal ring in a tube of peri-
toneum, the processus vaginalis, which now lies in the inguinal canal. The lower
part of the gubernaculum by the fifth month has become a thick cord, whilst the
upper part has disappeared. The lower part can now be seen to consist of a cen-
tral core of unstriped muscle-fibre, and outside this of a firm layer of striped
elements, connected, behind the peritoneum, with the abdominal wall. Later on,
about the sixth month, the lower end of the gubernaculum can be traced into the
inguinal canal, extending to the pubes, and, at a later period, to the bottom of
the scrotum. The fold of peritoneum constituting the processus vaginalis pro-
jects itself downward into the inguinal canal, forming a gradually elongating
depression or cul-de-sac, which eventually reaches the bottom of the scrotum. This
cul-de-sac is now invaginated by the testicle, as the body of the foetus grows, for the
gubernaculum does not grow commensurately with the growth of other parts, and
therefore the testicle, being attached by the gubernaculum to the bottom of the
1472 THE MALE ORGANS OF GENERATION
scrotum, is prevented from rising as the body grows, and is drawn first into the
inguinal canal, and eventually into the scrotum. By the eighth month the tes-
ticle has reached the scrotum, preceded by the lengthened pouch of peritoneum,
the processus vaginalis, which communicates by its upper extremity with the
peritoneal cavity. Just before birth the upper part of the pouch usually becomes
closed, and this obliteration extends gradually downward to within a short dis-
tance of the testis. The process of peritoneum surrounding the testis, which is now
entirely cut off from the general peritoneal cavity, constitutes the tunica vaginalis.1
Mr. Jacobson2 says that the attachments of the gubernaculum above are to
the vas, the epididymis, and afterward to the testicle. The lower attachments
of the gubernaculum, some of which are temporary, are the abdominal wall,
pubes and root of the scrotum, Scarpa's triangle, perinseum and scrotum. The
remains of the scrotal fibres constitute a so-called ligament of the scrotum or
the mesorchium, which causes adhesion between the testicle and skin (Fig. 1086).
In the female, a small cord, corresponding to the gubernaculum in the male,
descends to the inguinal region and ultimately forms the round ligament of the
uterus. A pouch of peritoneum accompanies it along the inguinal canal, analogous
to the processus vaginalis in the male ; it is called the canal of Nuck.
Surgical Anatomy. — Abnormalities in the formation and in the descent of the testicle may
occur. The testicle may fail to be developed, or it may be fully developed and the vas deferens
may be undeveloped in whole or in part; or, again, both testicle and vas deferens may be fully
developed, but the duct may not become connected to the gland. The testicle may fail in its
descent (cryptorchismus) or it may descend into some abnormal position (ectopia testis) . Thus it
may be retained in the position where it was primarily developed, below the kidney; or it may
descend to the internal abdominal ring, but fail to pass through this opening; it may be retained
in the inguinal canal, which is perhaps the most common position; or it may pass through the
external abdominal ring and remain just outside it, failing to pass to the bottom of the scrotum.
On the other hand, it may get into some abnormal position; it may pass the scrotum and reach
the perinseum, or it may fail to enter the inguinal canal, and may find its way through the fem-
oral ring into the crural canal, and present itself on the thigh at the saphenous opening. Ectopia
testis is due to the absence, overdevelopment or malposition of some portion of the gubernacu-
lum. There is still a third class of cases of abnormality in the position of the testicle, where the
organ has descended in due course into the scrotum, but is malplaced. The most common form
of this is where the testicle is inverted; that is to say, the organ is rotated, so that the epididymis
is connected to the front of the scrotum, and the body, surrounded by the tunica vaginalis, is
directed backward. In these cases the vas deferens is to be felt in the front of the cord. The
condition is of importance in connection with hydrocele and ha;matoeele, and the position of
the testicle should always be carefully ascertained before performing any operation for these
affections. Again, more rarely, the testicle may be reversed. This is a condition in which the
top of the testicle, indicated by the globus major of the epididymis, is at the bottom of the
scrotum, and the vas deferens comes off from the summit of the organ.
THE COVERINGS OF THE TESTICLE (Fig. 1088).
The coverings of the testicle are the following:
Skin ) 0
T>. > Scrotum.
Dartos j
Intercolumnar or External spermatic fascia.
Cremasteric fascia.
Infundibuliform or Fascia propria (Internal spermatic fascia).
Tunica vaginalis.
The Testicular Bag or Scrotum (Figs. 1086 and 1087). — The testicular bag or
scrotum is a cutaneous pouch which contains the testes and part of the spermatic
cords. It is divided on its surface into two lateral portions by a median line or
1 The obliteration of the process of peritoneum which accompanies the cord, and is hence called the funicular
process, is often incomplete. See section on Inguinal Hernia.
2 Diseases of the Male Organs of Generation.
THE COVERINGS OF THE TESTICLE
1473
raphe* (raphe scroll), which is continued forward to the under surface of the penis
and backward along the middle line of the perinaeum to the anus. Of these two
lateral portions, the left is usually longer than the right, and corresponds with the
usual greater length of the spermatic cord on the left side. Its external aspect varies
under different circumstances: thus under the influence of warmth and in old and
debilitated persons it becomes elongated and flaccid, but under the influence of cold
and in the young and robust it is short, corrugated, and closely applied to the
testes. The wrinkles in the scrotum are called rugae.
The scrotum consists of two layers, the integument and the dartos.
RIGHT INGUINAL CANAL
(OPENED)
CREMASTERIC MUSCLE-
AMD FASCIA
INTERCOLUMNAR
FASCIA
PERSISTENT SEROUS
CAVITY AROUND
CORD — EXCEPTIONAL
TUNICA VAQINALIS
PARIETAL LAYER
— -INFUNDIBULIFORM
FASCIA
NON-PEDUNCULATED
RIGHT HALF OF SCROTUM SKIN
LEFT HALF OF SCROTUM
FIG. 1086. — The scrotum. On the left side the cavity of the tunica vaginalis has been opened ; on the
right side only the layers superficial to the cremaster have been removed. (Testut.)
The Integument. — The integument is very thin, of a brownish color, and gen-
erally thrown into folds or rugae. It is provided with sebaceous follicles, the
secretion of which has a peculiar odor, and is beset with thinly-scattered, crisp
hairs, the roots of which are seen through the skin.
The Dartos (tunica dartos) (Figs. 1079 and 1086). — The dartos is a thin layer, of
loose tissue, endowed with contractility; it forms the proper tunic of the scrotum,
is continuous around the base of the scrotum, with the two layers of the super-
ficial fascia of the groin and perinaeum, and sends inward a distinct septum,
the septum of the scrotum (septum scroll] (Fig. 1086), which divides it into two
cavities for the two testes, the septum extending between the raphe' and the.
under surface of the penis as far as its root.
The dartos is closely united to the skin externally, but connected with the
93
1474
THE MALE ORGANS OF GENERATION
subjacent parts by delicate areolar tissue, upon which it glides with the greatest
facility. The dartos is very vascular, and consists of a loose areolar tissue con-
taining unstriped muscular fibre, but no fat. Its contractibility is slow, and
excited by cold and mechanical stimuli, but not by electricity.
The Intercolumnar or Spermatic Fascia (Fig. 1086). — The intercolumnar
fascia is a thin membrane derived from the margin of the pillars of the external
abdominal ring, during the descent of the testis in the foetus, which is prolonged
downward around the surface of the cord and testis. It is separated from the
EXTERNAL
ABDOMINAL
RING
ACCESSORY
SLIP OF
ORIGIN OF
CREMASTER
MUSCLE
SPERMATIC
CORD
CREMASTER
MUSCLE
SEPTUM
SCR01
VAS
DCFERENS
SPERMATIC
ARTERY
•NERVE-FILAMENTS
OF SPERMATIC
PLEXUS
DEFERENTIAL
ARTERY
INFUNDIBULIFORM
FASCIA
SPERMATIC
PLEXUS
EPIDIDYMIS
PARIETAL
LAYER OF
TUNICA
VAGINAL!
dartos by loose areolar tissue, which allows of considerable movement of the
latter upon it, but is intimately connected with the succeeding layers.
The Cremasteric Fascia (fascia cremasterica) (Figs. 1086 and 1087). — The
cremasteric fascia consists of scattered bundles of muscular fibres, the Cremaster
muscle (m. cremaster) (Figs. 1086 and 1087) connected together into a continuous
covering by intermediate areolar tissue. The muscular fibres are continuous
with the lower border of the Internal oblique muscle.
THE COVERINGS OF THE TESTICLE
1475
The Infundibuliform Fascia (tunica vaginalis communis) [testis etfuniculi sper-
matici]) (Figs. 1086 and 1087). — The infundibuliform fascia is a thin membranous
Skin.
Dartos.
External spermatic fascia.
Cremasteric fascia.
Infundibuliform fascia
Parietal tunica vayhtnli.i.
Visceral tunica vaginalis.-..
Tunica vasculosa.
Tunica albuginea. ...
A lobule of the testicle..^
A septum. J
Mediastinum..
Digital fossa.-.
Spermatic vein.
Epididymis.
Vas deferens. .
Artery to vas.
Spermatic artery.
Internal cremaster
muscle.
FIG. 1088. — Transverse section through the left side of the scrotum and the left testicle. The sac of the
tunica vaginalis is represented in a distended condition. (Del6pine.)
layer, which loosely invests the surface of the cord. It is a continuation downward
of the fascia transversal is. Beneath it is a quantity of loose connective tissue which
connects this layer of fascia with the spermatic cord and posterior parts of the tes-
SPERMATIC
ARTERY
.CHEMASTERIC
ARTERY
DEFERENTIAL
"ARTERY
SEMINAL
"DUCT
POSTERIOR
"•GROUP OF
VEINS
.ANASTOMOSIS
OF VEINS
FIG. 1089. — The arteries of the testicle and the cord. (Poirier'and Charpy.)
ticle. This connective tissue is continuous above with the subserous areolar tissue of
the abdomen. These two layers, the infundibuliform fascia and the tissue beneath
1476
THE MALE ORGANS OF GENERATION
it, are known collectively as the fascia propria. The infundibuliform fascia com-
pletely encloses the testicle and epididymis and is fused with the parietal lamina
of the tunica vaginalis propria testis.
The Tunica Vaginalis (tunica vaginalis propria testis}. — The tunica vagi-
nalis is described with the testis (p. 1480).
Vessels and Nerves. — The arteries supplying the coverings of the testis are:
the superficial and deep external pudic, from the femoral; the superficial perineal
branch of the internal pudic; and the cremasteric branch from the deep epigastric.
The veins follow the course of the corresponding arteries. The lymphatics term-
inate in the inguinal glands. The nerves are: the ilio-inguinal branch of the
lumbar plexus, the two superficial perineal branches of the internal pudic nerve,
the inferior pudendal branch of the small sciatic nerve, and the genital branch of
the genito-f emoral nerve.
TRANSVERSALIS
FASCIA
DEEP
EPIGASTRIC
ARTERY
LIGAMENT
OF CLOQUET
SPERMATIC
ARTERY
PAMPINIFORM
PLEXUS
SPERMATIC
CORD
FIG. 1090. — The spermatic cord and the ligament of Cloquet. (Poirier and Charpy.)
THE SPERMATIC CORD (FUNICULUS SPERMATICUS)
(Figs. 1086, 1087, 1090, 1091).
The spermatic cord extends from the internal abdominal ring, where the
structures of which it is composed converge, to the back part of the testicle. In
the abdominal wall the cord passes obliquely along the inguinal canal, lying at
first beneath the Internal oblique muscle and upon the fascia transversalis ; but
nearer the pubes it rests upon Poupart's ligament, having the aponeurosis of
the External oblique in front of it and the conjoined tendon behind it. It then
escapes at the external ring, and descends nearly vertically into the scrotum. The
left cord is usually rather longer than the right, consequently the left testis
generally hangs somewhat lower than its fellow.
Structure. — The spermatic cord contains the spermatic duct, the deferential
artery and veins, the spermatic artery, the pampiniform plexus of veins, the sper-
matic plexus, and the deferential plexus of the sympathetic nerve, lymphatics, and
the cord-like remnant of the funicular process of peritoneum called the ligament
THE SPERMATIC CORD
1477
of Gloquet (Fig. 1090). All the above structures are held together by connective
tissue. These structures are ensheathed by the infundibuliform process of the trans-
versalis fascia (Fig. 1096 and p. 1074). This fascia is thin above and thicker below,
and encloses the testicle and epididymis, as well as the cord, being firmly adherent
to the parietal layer of the vaginal tunic of the testicle and with the posterior portion
of the testicle and epididymis. Upon this fascia are the fibres of the Cremaster
muscle, which spring from the internal oblique, and in this fascia are the cremas-
teric artery, the genital branch of the genito-femoral nerve, and external sperma tic-
veins. This fascia is surrounded by the intercolumnar or spermatic fascia, which
is distinct above, but not below.
Vessels and Nerves of the Spermatic Cord. — The arteries (Figs. 1089 and 1096) of
the cord are: the spermatic, from the aorta; the artery of the vas deferens, from
the superior vesical; the cremasteric, from the deep epigastric.
VAS
DEFERENS
SPERMATIC
CORD
FIG. 1091. — The spermatic cord in the inguinal canal. (Poirier and Charpy.)
The spermatic artery (a. spermatica internd) arises from the abdominal aorta
below the renal artery, descends by the Psoas muscle, crosses the ureter and
external iliac vessels, meets the vas deferens at the internal abdominal ring,
escapes from the abdomen at the internal or deep abdominal ring, and lying in
front of the vas deferens accompanies the other constituents of the spermatic cord
along the inguinal canal and through the external abdominal ring into the scrotum.
It then descends to the testicle, and, becoming tortuous, divides into "several
branches, two or three of which, the epididymal branches, accompany the vas
deferens and supply the epididymis, anastomosing with the artery of the vas
deferens and the cremasteric artery; others, the glandular branches, pierce the back
of the tunica albuginea and supply the substance of the testis.
The artery of the vas deferens, a branch of the superior vesical, is a long slender
vessel which accompanies the vas deferens, ramifying upqn the coats of that duct,
and anastomosing with the spermatic artery and the cremasteric artery near the
testis.
1478
THE M4LE ORGANS OF GENERATION
The cremasteric artery (a. spermatica externa) is a branch of the deep epigas-
tric artery. It accompanies the spermatic cord and supplies the Cremaster
muscle and other coverings of the cord, anastomosing with the spermatic and
deferential arteries.
The spermatic veins (Figs. 1089, 1090, 1091, and 1093) emerge from the back of
the testis and receive tributaries from the epididymis; they unite and form a con-
voluted plexus, the pampiniform plexus (plexus .pampinif or mis] , which forms the
chief mass of the cord ; the vessels composing this plexus are very numerous, and
ascend along the cord in front of the vas deferens; below the external or super-
CORPUS
CAVERNOSUM
COWPER'S
GLAND
BUtBO-
CAVERNOSUS
MUSCLE
FIG. 1092. — Male pelvic organs seen from right side. Bladder and rectum distended; relations of peritoneum
to the bladder and rectum shown in blue. The arrow points to the vesico-rectal pouch. (Corning.)
ficial abdominal ring they unite to form three or four veins, which pass along the
inguinal canal, and, entering the abdomen through the internal or deep abdominal
ring, coalesce to form two veins. These again unite to form a single vein, which
opens on the right side into the postcava at an acute angle, and on the left side
into the renal vein at a right angle.
The lymphatic vessels of the scrotum terminate in the superficial inguinal
glands.' The lymphatics of the testicle join the lymphatics of the epididymis and of
the visceral layer of the vaginal tunic of the testicle, and ascend in the spermatic
cord. They reach the lumbar region along the spermatic blood-vessels and ter-
minate in the juxta-aorta glands, and sometimes in the glands in front of the
aorta. The lymphatics of the seminal duct pass to the external iliac glands.
The nerves are the spermatic plexus from the sympathetic, joined by filaments
from the pelvic plexus which accompany the artery of the vas deferens.
The Ligament of the Scrotum. — See Fig. 1085 and p. 1472.
Surgical Anatomy. — The scrotum forms an admirable covering for the protection of the
testicle. This body, lying suspended and loose in the cavity of the scrotum, and surrounded by
'/'///•; TESTICLES
1479
a serous membrane, is capable of great mobility, and can therefore easily slip about within the
scrotum, and thus avoid injuries from blows or squeezes. The skin of the scrotum is very
elastic and capable of great distention, and on account of the looseness and amount of subcu-
taneous tissue the scrotum becomes greatly enlarged in cases of (edema, to which this part is
especially liable on account of its dependent position. The scrotum is frequently the seat of
epithelioma; this is no doubt due to the rugae on its surface, which favor the lodgement of dirt,
and this, causing irritation, is the exciting cause of the disease. Cancer was especially common
in chimney-sweeps from the lodgement of soot. The scrotum is also the part most frequently
affected by elephantiasis.
On account of the looseness of the subcutaneous tissue considerable extravasations of blood
may take place from very slight injuries. It is therefore generally recommended never to apply
leeches to the scrotum, since they may lead to considerable ecchymosis, but rather to puncture
one or more of the superficial veins of the scrotum in cases where local bloodletting from this
part is judged to be desirable. The muscular fibre in the dartos causes contraction and consider-
able diminution in the size of a wound of the scrotum, as after the operation of castration, and
is of assistance in keeping the edges together and covering the exposed parts.
FIG. 1093. — Spermatic veins. (Testut.)
THE TESTICLES (TESTES) (Figs. 1084, 1086, 1087, 1094, 1095).
The testicles are suspended in the scrotum by the spermatic cords. As the left
spermatic cord is rather longer than the right one, the left testicle hangs somewhat
lower than its fellow. Each gland is of an oval form, compressed laterally, and
having an oblique position in the scrotum, the upper extremity (extremitus superior)
being directed forward and a little outward, the lower extremity (extremitus infe-
rior], backward and a little inward; the anterior convex border (margo anterior)
1480
THE MALE ORGANS OF GENERATION
looks forward and downward; the posterior or straight border (marcjo posterior],
to which the cord is attached, backward and upward.
The anterior border and lateral surfaces (fades latcralis el fades medialis), as well
as both extremities of the organ, are convex, free, smooth, and invested by the
visceral layer of the tunica vaginalis. The posterior border, to which the cord is
attached, receives only a partial investment from that membrane. Lying upon
the outer edge of this posterior border is a long, narrow, flattened body, named,
from its relation to the testis, the epididymis (dido not;, testis) (Figs. 1094 and 1095).
The curve of the epididymis is convex outward and backward. It consists of
a central portion or body (corpus epididymidis) ; an upper enlarged extremity, the
head or globus major (caput epididymidis) ; and a lower pointed extremity, the tail
or globus minor (cauda epididymidis}. The globus major is directed inward and
is intimately connected with the upper end of the testicle by means of its efferent
ducts, and the globus minor is connected with its lower end by cellular tissue and a
reflection of the tunica vaginalis. The globus minor bends suddenly and passes
into the seminal duct, the direction of which is upward and backward. The outer
surface and upper and lower ends of the epididymis are free and covered by
serous membrane; the body is also completely invested by it, excepting along its
posterior border, and between the body and the testicle is a pouch or cul-de-sac,
named the digital fossa (sinus epididymidis) . Above this fossa is a fold of the
tunica vaginalis, which is called the ligamentum epididymidis superior, and below
it is another fold, the ligamentum epididymidis inferior. The epididymis is con-
nected to the back of the testis by a fold of the serous membrane. Attached to
the up^er end of the testis, close to the globus major, is a small body. It is oblong
in shape and has a broad base. Attached to the globus major of the epididymis
is another small body, which is pear-shaped and has a stalk. These bodies are
believed to be the remains of the upper extremity of the Miillerian duct, and are
termed the hydatids of Morgagni; some observers, however, regard the stalked
hydatid as being a rudiment of the pronephros. The body with a broad base is
the non-pedunculated hydatid (appendix testis [Morgagnii]) (Figs. 1086 and 1094) ;
Spermatic cord.
Tunica vaginalis,
parietal layer.
Non-pedunculated
hydatid.
Digital
fossa.
Artery of
~ cord.
MEDIASTINUM
TESTIS
ALBUGINEA
FIG. 1094. — The testis in situ, the tunica vaginalis
having been laid open.
FIG. 1095. —Frontal section of the testicle and
epididymis. (Poirier and Charpy.)
the pear-shaped body is the pedunculated hydatid (appendix epididymidis) . When
the testicle is removed from the body, the position of the vas deferens, on the
THE TESTICLES
1481
Tunica Vaginalis
Tunica Albug
Its Septa
Tubuli
seminiferi
contorti.
Ductuli
efferentes.
Tubuli
seminiferi
recti.
posterior surface of the testicle and inner side of the epididymis, marks the side
to which the gland has belonged.
Size and Weight. — The average dimensions of this gland are from one and a
half to two inches in length, one inch in breadth, and an inch and a quarter in
the antero-posterior diameter, and the weight varies from six to eight drachms,
the left testicle being a little the larger.
The Tunics of the Testicle.— The testis is invested by three tunics— the tunica
vaginalis, tunica albuginea, and tunica vasculosa.
The Proper Sheath of the Testicle or the Tunica Vaginalis (tunica vaginalis propria
testis) (Figs. 1084, 1086, 1087, 1088, and 1096) is the serous covering of the testicle
and epididymis. It is a pouch
of serous membrane, derived
from the peritoneum (processus
vaginalis peritonaei) during the
descent of the testis in the foetus
from the abdomen into the scro-
tum. After its descent that por-
tion of the pouch which extends
from the internal ring to near the
upper part of the gland, the
funicular process, becomes oblit-
erated, the lower portion re-
maining as a shut sac, which
invests the outer surface of the
testis, and is reflected on to the
internal surface of the scrotum;
hence it may be described as
consisting of a visceral and
parietal portion.
The Visceral Portion (lamina
visceralis) of the tunica vaginalis
propria covers the outer surface
of the testis, as well as the epi-
didymis, connecting the latter to the testis by means of a distinct fold. From the
posterior border of the gland it is reflected on to the internal surface of the infun-
dibuliform process of the transversalis fascia, and between the tunic and the fascia
is a layer of unstriated muscle fibres, the Internal cremaster muscle (Fig. 1088).
The Parietal Portion (lamina parietalis) of the tunica vaginalis propria is the
reflected portion. It is far more extensive than the visceral portion, extending
upward for some distance in front and on the inner side of the cord, and reaching
below the testis. The inner surface of the tunica vaginalis is free, smooth, and
covered by a layer of endothelial cells. The interval between the visceral and
parietal layers of this membrane constitutes the cavity of the tunica vaginalis and
contains a small amount of serous fluid.
The obliterated portion of the pouch may generally be seen as a fibro-cellular
thread, the ligament of Cloquet (rudimentum processus vaginalis} (Fig. 1090), lying
in the loose areolar tissue around the spermatic cord; sometimes this may be traced
as a distinct band from the upper end of the inguinal canal, where it is connected
with the peritoneum, down to the tunica vaginalis; sometimes it gradually becomes
lost on the spermatic cord. Occasionally no trace of it can be detected. In some
cases it happens that the pouch of peritoneum does not become obliterated, but
the sac of the peritoneum communicates with the tunica vaginalis. This may
give rise to one of the varieties of oblique inguinal hernia; or in other cases the
FIG. 1096. --Vertical section of the testicle, to show the arrange-
ment of the ducts.
1482 THE MALE ORGANS OF GENERATION
pouch may contract, but not become entirely obliterated; it then forms a minute
canal leading from the peritoneum to the tunica vaginalis.1
The Tunica Albuginea (Figs. 1088, 1095, and 1096). — The tunica albuginea is the
fibrous covering of the testis. It is a dense fibrous membrane, of a bluish-white
color, composed of bundles of white fibrous tissue, which interlace in every direc-
tion. Its outer surface is covered by the tunica vaginalis, except at the points of
attachment of the epididymis to the testicle, and along its posterior border, where
the spermatic vessels enter the gland. This membrane surrounds the glandular
structure of the testicle, and at its posterior border forms a projection, triangular
in shape and cellular in structure, which is reflected into the interior of the gland,
forming an incomplete vertical septum, called the mediastinum testis.
The Mediastinum Testis (corpus Highmori) (Figs. 1088, 1095, and 1096) extends
from the upper, nearly to the lower, extremity of the gland, and is wider above
than below. From the front and sides of this septum numerous slender fibrous
cords and imperfect septa, called the trabeculae (septula testis] (Fig. 1096), are
given off, which radiate toward the surface of the organ, and are attached to the
inner surface of the tunica albuginea. This scaffolding of connective tissue divides
the parenchyma (parenchyma testis) of the organ into a number of incomplete
spaces, which are somewhat cone-shaped, being broad at their bases at the sur-
face of the gland, and becoming narrower as they converge to the mediastinum.
The mediastinum supports the blood-vessels, lymphatics, and ducts of the testis
in their passage to and from the substance of the gland, and contains numerous
fine canals, into which open the very small tubules of the proper substance of
the testicle.
The Tunica Vasculosa (Fig. 1088). — The tunica vasculosa is the vascular layer of
the testis, and consists of a plexus of blood-vessels held together by a delicate
areolar tissue. It covers the inner surface of the tunica albuginea and the dif-
ferent septa in the interior of the gland, and therefore forms an internal invest-
ment to all the spaces of which the gland is composed.
Structure of the Testicle and Epididymis (Fig. 1096). — The glandular struc-
ture of the testis -consists of numerous lobules (lobuli testis}. Their number, in a
single testis, is estimated by Berres at 250, and by Krause at 400. They differ in size
according to their position, those in the middle of the gland being larger and longer.
The lobules are conical in shape, the base of each being directed toward the circum-
ference of the organ, the apex toward the mediastinum. Each lobule is contained in
one of the intervals between the fibrous cords and vascular processes which extend
between the mediastinum testis and the tunica albuginea, and consists of from one
to three or more minute convoluted tubes, which anastomose with each other, the
tubuli seminiferi contorti. The contorted tubes unite at the apex of the lobules and
form the straight tubes (tubuli seminiferi recii). The straight tubes pass into the
mediastinum testis and form the network known as the rete testis of Haller (Fig.
1096). The rete testis is lined with flattened epithelium. The tubes are lined with
columnar ciliated epithelium. The efferent ducts (ductuli efferentes testis)(Fig. 1096),
about twelve to fifteen in number, arise from the rete. The contorted tubes may
be separately unravelled by careful dissection under water, and may be seen to
commence either by free caecal ends or by anastomotic loops. The total number of
tubes is considered by Munro to be about 300 and the length of each about sixteen
feet; by Lauth their number is estimated at 840, and their average length two feet
and a quarter. The diameter varies from ^ru- to rsir °f an mcn- The tubuli are
pale in color in early life, but in old age they acquire a deep-yellow tinge from
containing much fatty matter. Each tube consists of a basement layer, formed
1 It is recorded that in the post-mortem examination of Sir Astley Cooper a minute funicular canal was found
01 each side of the body. Sir Astley Cooper states that when a student he suffered from inguinal hernia; prob-
ably this was of the congenital variety, and the canal found after death was the remains of the one down which
the hernia travelled (Lancet, 1824, vol. ii. p. 116). — ED. of 15th English edition.
THE TESTICLES 1483
of epithelioid cells united edge to edge, outside of which are other layers of
flattened cells arranged in interrupted laminae, which give to the tube an appear-
ance of striation in cross-section. The cells of the outer layers gradually pass
into the interstitial tissue. Within the basement-membrane are epithelial cells
arranged in several irregular layers, which are not always clearly separated, but
which may be arranged in three different groups. Among these cells may be seen
the spermatozoids in different stages of development. 1. Lining the basement-
membrane and forming the outer zone is a layer of cubical cells, with small
nuclei; these are known as the lining cells or spermatogonia. The nucleus of some
of them may be seen to be in the process of indirect division (karyokinesis), and
in consequence of this daughter cells are formed, which constitute the second zone.
2. Within this first layer is to be seen a number of larger cells with clear nuclei,
arranged in two or three layers; these are the intermediate cells or spermatocytes.
Most of these cells are in a condition of karyokinetic division, and the cells which
result from this division form those of the next layer, the spermatoblasts or sperma-
tids. 3. The third layer of cells therefore consists of the spermatoblasts or sperma-
tids, and each of these, without further subdivision, becomes a spermatozoid. They •
are ill-defined granular masses of protoplasm, of an elongated form, with a nucleus
which becomes the head of the future spermatozoid. In addition to these three
layers of cells others are seen, which are termed the supporting cells, or cells of
Sertoli. They are elongated and columnar, and project inward from the basement-
membrane toward the lumen of the tube. They give off numerous lateral branches,
which form a reticulum for the support of the three groups of cells just described.
As development of the spermatozoids proceeds the latter group themselves around
the inner extremities of the supporting cells. The nuclear part of the sperma-
tozoid, which is partly embedded in the supporting cell, is differentiated to form the
head of the spermatozoid, while the cell protoplasm becomes lengthened out to
form the middle piece and tail, the latter projecting into the lumen of the tube.
Ultimately the heads are separated and the spermatozoids are set free.
Spermatogenesis. — The stages in the development of the spermatozoids are as
follows: The spermatogonia become enlarged to form the spermatocytes, and
each spermatocyte subdivides into two cells, and each of these again divides into
two spermatids or young spermatozoids, so that the spermatocyte gives origin to
four spermatozoids.
The process of spermatogenesis bears a close relation to that of maturation of
the ovum. The spermatocyte is equivalent to the immature ovum. It undergoes
subdivision, and ultimately gives origin to four spermatozoids, each of which con-
tains, therefore, only one-fourth of the chromatin elements of the nucleus of the
spermatocyte. In the process of maturation of the ovum its nucleus divides, one-
half being extended as the first polar body. The remaining half of the nucleus
again subdivides, one-half being extended as the second polar body. The portion
of the nucleus which is retained to form the female pronucleus of the now matured
ovum contains, therefore, only one-fourth of the chromatin elements of the
original nucleus, and thus the spermatozoid and the matured ovurn, so far as
their nuclear elements are concerned, may be regarded as of the same morpho-
logical value.
The tubules are enclosed in a delicate plexus of capillary vessels, and are held
together by an intertubular connective tissue, which presents large interstitial
spaces lined by endothelium, which are believed to be the rootlets of lymphatic
vessels of the testis.
The Aberrant Ducts of the Epididymis (ductuli aberrantes) are tortuous and end
in blind extremities. The superior aberrant duct (ductus abcrrans superior) is in the
globus major and joins the rete testis. The inferior aberrant duct (ductus aberrans
inferior) (Fig. 1096) is in the tail of the epididymis, and takes origin from the
1484 THE MALE ORGANS OF GENERATION
duct of the epididymis or the seminal duct. It is a persistent canal of the Wolffian
body. It extends up the cord for two or three inches and terminates by a blind
extremity, which is occasionally bifurcated. It may be as much as fourteen inches
in length. Its structure is similar to that of the seminal duct.
The Seminal Duct or Vas Deferens (ductus deferens) (Figs. 1089, 1090, 1091, 1096,
1097, and 1 135). — The seminal duct or vas deferens, the excretory duct of the testis,
is the continuation of the epididymis. Commencing at the lower part of the globus
minor, it ascends along the posterior border of the testis and inner side of the epi-
didymis, and along the back part of the spermatic cord, through the inguinal canal
to the internal or deep abdominal ring. From the ring it curves around the outer
side of the internal epigastric artery and vein, crosses the external iliac vessels, and
descends into the pelvis at the side of the bladder; it arches backward and down-
ward to its base, crossing over the obliterated hypogastric artery and to the inner
side of the ureter. At the base of the bladder it lies between that viscus and the
rectum, running along the inner border of the seminal vesicle. Behind the bladder
it becomes enlarged and sacculated, forming the ampulla (ampulla ductus deferentis)
(Fig. 1097), and then, becoming narrowed at the base of the prostate, unites with
the duct of the seminal vesicle to form the ejaculatory duct (Fig. 1098). From the
internal abdominal ring to the middle of the ampulla the seminal duct is beneath
the peritoneum. The vas deferens offers a hard and cord-like sensation to the
fingers; it is about two feet in length, of cylindrical form, and about a line and
a quarter in diameter. Its walls are dense, measuring one-third of a line, and its
canal is extremely small, measuring about half a line.
Structure. — The vas deferens consists of three coats: 1. An external or areolar
coat (tunica adventitia). 2. A muscular coat (tunica muscularis) , which in the
greater part of the tube consists of two layers of unstriped muscular fibre : an inner
layer of thin longitudinal fibres (stratum internum) existing only at the beginning,
a thick layer of circular fibres (stratum medium), and a thick external layer of
longitudinal fibres (stratum externum). 3. An internal or mucous coat (tunica
mucosd), which is pale, and arranged in longitudinal folds; its epithelial cells are
of the columnar variety.
Organ of Giraldes (paradidi/mis). — This term is applied to a small body of
rounded shape in the lower end of the spermatic cord, in front of the blood-
vessels. It consists of a small collection of minute vesicles and a small collection
of convoluted tubules. These tubes are lined with columnar ciliated epithelium,
and probably represents the remains of a part of the Wolffian body.
Surgical Anatomy. — Abnormalities in the descent and position of the testicle have been
discussed (p. 1472). The testicle may require removal for malignant disease, tuberculous disease,
cystic disease, in cases of large hernia testis, and in some instances of incompletely descended or
misplaced testicles. The operation of double castration has also been, during the last few years,
performed for enlargement of the prostate gland ; for it has been found that removal of the tes-
ticles is followed by very rapid and often considerable diminution in the size of the prostate.
The operation is, however, one of severity, and is frequently followed by death in these cases,
performed, as it necessarily is, in old men. Reginald Harrison has proposed to substitute for it
excision of a portion of each vas deferens (vasectomy). The operation of castration is a com-
paratively simple one. An incision is made into the cavity of the tunica vaginalis from the
external ring to the bottom of the scrotum. The coverings are shelled off the organ, and the
mesorchium, stretching between the back of the testicle and the scrotum, divided. The cord is
then isolated, and an aneurism needle, armed with a double ligature, passed under it, as high
as is thought necessary, and the cord tied in two places, and divided between the ligatures.
Sometimes, in cases of malignant disease, it is desirable to open the inguinal canal and tie the
cord as near the internal abdominal ring as possible.
A collection of serous fluid in the sac of the vaginal tunic of the testicle is known as an ordinary
or testicular hydrocele. In congenital hydrocele a communication remains between the tunica
vaginalis testis and the peritoneal cavity. This communication should have closed during
development. In infantile hydrocele the tunica vaginalis and part of the funicular process are
distended with fluid, but the funicular process is closed above and the cavity of the hydrocele
THE TESTICLES
1485
does not communicate with the peritoneal cavity. In encysted hydroceleof the cord the funicular
process is closed above and below, but between these points is not obliterated. In funicular
hydrocele the funicular process is closed below and open above. Congenital hydrocele can
usually be cured by the application of a truss. This obliterates the upper end of the funicular
process, and the obliteration once begun may proceed to completion. If it does not, the condi-
tion has become an infantile hydrocele. An infantile hydrocele can usually be cured by multiple
punctures or tapping. The same is true of encysted hydrocele of the cord. In hydrocele of the
funicular process wear a truss for a time and then tap. In ordinary testicular hydrocele incise
and pack, or incise and suture, the cut edge of the parietal layer of the tunic to the skin, or extir-
pate the parietal layer of the tunic. A successful method is that of Longuet. He makes an
incision, pulls out the testicle, and allows all the coats except the skin to fall behind and make
a sheath for the cord. These coats are held behind by one catgut suture. A bed is made for
the testicle beneath the skin toward the septum of the scrotum. The testicle is rotated on its
long axis and placed in the bed, and the skin is sutured above it. This operation is known
as extraserous transposition. If a portion of bowel enters an open vaginal process the condition
is congenital hernia.
In infantile hernia the funicular process is closed above but not below, and the hernia descends
in a specfal sac back of the vaginal tunic. If the hernia pushes down on the vaginal process and
causes it to double on itself the condition is encysted infantile hernia.
.Head
Middle
' piece
'Main piece
•
Head — gfl
Middle _l
piece
The Semen and the Spermatozoids. — Semen consists of spermatozoids with liquids
and solids. Part of the semen comes from the testicles, most of it from accessory
glands — that is, from the glands of the seminal ducts, the seminal vesicles, the pros-
tate gland, and Cowper's glands. Semen is a viscid,
whitish fluid, of alkaline reaction and characteristic
odor. It contains water and about 18 per cent, of
solid matter. In this solid matter are fat, choles-
terin, lecithin, proteids, nuclein, xanthin, chlorides,
sulphates, and phosphates of sodium and potassium.
Bottcher's crystals, which can be obtained from
semen, are composed of phosphate of spermine.
Spermine is a nitrogenous substance. The fluid
portion of semen carries and probably nourishes the
living cells known as spermatozoids.
The spermatozoids (Fig. 1097) are minute, thread-
like bodies, which constitute the essential elements
of the semen. Each consists of a head, a middle
piece or body, and an elongated filament or tail.
The head, on surface view, appears oval in shape,
but if seen in profile it is narrow and pointed at its
free end. It represents the modified nucleus of the
spermatid, and consists chiefly of chromatin, and so
stains readily with nuclear reagents; it is covered by
a thin cap of protoplasm. The body is a short
cylindrical or conical piece, intervening between the
head and tail, and is therefore sometimes spoken of
as the intermediate segment. The tail is about four
times the combined lengths of the head and body; its terminal part is extremely
fine, and is named the end-piece. Contained within the body and tail is an axial
filament, surrounded, except in the end -piece, by a thin layer of protoplasm; this
axial filament terminates just below the head in a rounded knob or button. In
virtue of their tails, which act as propellers, the spermatozoids, in the fresh con-
dition, are capable of free movement, and if placed in favorable surroundings
(e. g., in the female passages) may retain their vitality for some. days or even
weeks. •
of
the
tail
—End piece
FIG. 1097. — Spermatozoid of man.
At the left a surface view is shown;
at the right a lateral view. X 1200.
(Szymonowicz, after Retzius.)
1486 THE MALE ORGANS OF GENERATION
THE SEMINAL VESICLES (VESICULAE SEMINALES) (Figs. 1098, 1099).
The seminal vesicles are two tabulated membranous pouches placed between
the base of the bladder and the rectum, serving as reservoirs for the semen, and
secreting a fluid to be added to the secretion of the testicles. Each sac is some-
what pyramidal in form, the broad end being directed backward and the narrow
end forward toward the prostate. It measures about two and a half inches in
length, about five lines in breadth, and two or three lines in thickness. They
vary, however, in size, riot only in different individuals, but also in the same
individual on the two sides. The upper surface is in contact with the base of
the bladder, extending from near the termination of the ureters to the base of
the prostate gland. The under surface rests upon the rectum, from which it is
separated by the recto-vesical fascia. - Their posterior extremities diverge from
VAS
DEFERENS
COWPER'S EXCRETORY
GLANDS DUCT
FIG. 1098. — The urinary bladder, distended, with surrounding structures, viewed from behind. (Spalteholz.)
each other. Their anterior extremities are pointed, and converge toward the base
of the prostate gland, where each joins with the corresponding seminal duct to
form the ejaculatory duct. Along the inner margin of each vesicle runs the
enlarged and convolutsd vas deferens. The inner border of the vesicle and the
corresponding seminal duct form the lateral boundaries of a triangular space,
limited behind by the recto-vesical peritoneal fold; the portion of the bladder
included in this space rests on the rectum.
Each vesicle consists of a single tube, coiled upon itself and giving off several
irregular caecal diverticula (Fig. 1098), the separate coils, as well as the diverticula,
being connected together by fibrous tissue. When uncoiled this tube is about the
diameter of a quill, and varies in length from four to six inches; it terminates pos-
teriorly in a cul-de-sac; its anterior extremity becomes constricted into a narrow
straight duct, the excretory duct (ductus excretorius] (Fig. 1099), which joins with
the corresponding seminal duct, and forms the ejaculatory duct.
THE TESTICLES
1487
The Ejaculatory Ducts (ductus ejaculatorii) (Fig. 1099). — The ejaculatory ducts
are two in number, oneon each side. Each duct is formed by the junction of the duct
of the seminal vesicle with the seminal duct. Each duct is about three-quarters of
an inch in length ; it commences at the base of the prostate, and runs forward and
downward between the middle and lateral lobes of that gland, and along the side
of the sinus pocularis, to terminate by a separate slit-like orifice close to or just
within the margins of the sinus. The ducts diminish in size and also converge
toward their termination.
Structure. — The seminal vesicles are composed of three coats: an external or
areolar (tunica adventitia) ; a middle or muscular coat (tunica muscularis) , which
is thinner than in the seminal duct, and is arranged in two layers, an outer,
longitudinal, and inner, circular; an internal or mucous coat (tunica mucosa),
which is pale, of a whitish-brown color, and presents a delicate reticular struc-
ture, like that seen in the gall-bladder, but the meshes are finer. The epithelium
is columnar.
VERUMONTANUM
EXCRETORY
DUCT
EJACULATORY
DUCT
SINUS
POCULARIS
URETHRA
FIG. 1099. — The ejaculatory ducts viewed from in front and above. (Spalteholz.>
The coats of the ejaculatory ducts are extremely thin. They are: an outer
fibrous layer, which is almost entirely lost after the entrance of the duct into the
prostate; a layer of muscular fibres, consisting of an outer thin circular and an
inner longitudinal layer; and the mucous membrane.
Vessels and Nerves. — The arteries supplying the seminal vesicles are derived
from the middle and inferior vesical and middle haemorrhoidal. The veins and
lymphatics accompany the arteries. The lymphatics anastomose on the surface
of the vesicle. The trunks from this network anastomose with the lymphatics
of the bladder and prostate, and pass to the external and internal iliac glands.
The nerves are derived from the pelvic plexus.
Surgical Anatomy. — The seminal vesicles are often the seat of an extension of the dis-
ease in cases of tuberculosis of the testicle, and should always be examined through the rectum
before coming to a decision with regard to castration in this affection. The vesicles have been
deliberately extirpated for local tuberculosis. In gonorrhoea the seminal vesicles may become
acutely inflamed (acute seminal vesiculitis) . Chronic seminal vesiculitis may follow the acute
form or may arise insidiously during gonorrhoea.
THE FEMALE ORGANS OF GENERATION.
EXTERNAL ORGANS (PARTES GENITALES EXTERNAL MULIEBRES).
THE external organs of generation in the female are: the mons Veneris, the
labia majora and minora, the vestibule, the clitoris, the vaginal bulb, and the
glands of Bartholin. The term vulva (pudendum muliebre), as generally applied,
includes all of these parts. In examining the structures entering into the formation
of the vulva we find the homologues of most of the structures which make up the
male genitals.
FALLOPIAN TUBE
PAROOPHORON
UTERINE ORIFICE
OF FALLOPIAN TUBE
INFUNDIBULUM OF
FALLOPIAN TUBE
PAVILION OF
FALLOPIAN TUBE
ORGAN OF
ROSENMULLCR
PERITONEUM
LABIUM
MINUS
LABIUM
MAJUS
VESTIBULE OF VAGINA
FIG. 1100. — Diagrammatic representation of the female reproductive organs and their relations to the bladder
and urethra, lateral view. (Toldt.)
Labia majora
Clitoris
Bulbus vestibuli
Vestibular Glands
(of Bartholin).
Scrotum.
Corpora cavernosa.
Corpus spongiosum.
Bulbo-urethral Glands
(of Cowper).
THE LARGE LIPS OR LABIA MAJORA (LABIA MAJORA PUDENDI)
'(Figs. 1101, 1102, 1103).
The labia majora are two prominent longitudinal cutaneous folds, narrow
behind but fuller and larger toward the mons Verieris, and enclosing the pudendal
slit (rami pudendi) or common urino-genital opening. Each labium majus (labium
94 ( 1489 )
1490
THE FEMALE ORGANS OJ GENERATION
majus pudendi) has two surfaces, an outer, which is covered by pigmented skin
with numerous sebaceous glands and strong, crisp hairs, and an inner, which is
smooth and moist, and is continuous with the gen i to-urinary mucous tract. In
the subcutaneous areolo-fatty tissue of each labium majus the round ligament of
the uterus ends. The labia are joined with each other anteriorly by the mons
Veneris or anterior commissure (commissura labiorum anterior). Posteriorly they
MONS VENERIS
ANTERIOR
OMMISSURE
OF VULVA
PREPUCE OF
CLITORIS
POSTERIOR
COMMISSURE
OF VULVA
VULVA I.
CLEFT
-PERINEUM
POST-ANAL.
FURROW
FIG. 1101. — The female pudendum or vulva with the labia majora. (Toldt.)
appear to become lost in the neighboring integument, although sometimes con-
nected by a slight transverse fold in front of the anus, the posterior commissure
(commissura labiorum posterior) or posterior boundary of the vulvar orifice. The
interval between the posterior commissure and the anus, about an inch in length,
constitutes the obstetric perinaeum.
Blood-vessels, Nerves, and Lymphatics. — The arteries of the labia majora are
derived from the superficial external pudic arteries and from perineal branches of the
internal pudic arteries. Homologous with the scrotum, the nerve-supply is derived
from branches of the ilio-inguinal, internal pudic, and perineal branches of the small
sciatic. The lymphatics drain into the superficial inguinal and internal iliac lymph-
nodes.
THE SMALL LIPS, NYMPHAE OR LABIA MINQRA (LABIA MINORA
PUDENDI) (Figs. 1101, 1102, 1103).
The labia minora, or nymphae, are two smaller, narrower longitudinal folds,
with a delicate covering of modified skin, and usually hidden from view unless the
labia majora are separated. They end posteriorly by gradually joining the labia
THE CLITORIS
1493
THE CLITORIS (Figs. 1102, 1103, 1105).
The clitoris is an erectile structure which is the morphologic homologue of the
penis; unlike the penis, however, it is not traversed by the urethra. It is situated
beneath the anterior commissure (or mons Veneris) partially hidden between the
anterior extremities of the labia minora. It is composed of a body and two crura;
the extremity of the body is surmounted by a small glans.
SUSPENSORY
LIGAMENT OF OVARY
BROAD LIGAMENT
or UTERUS
FIG. 1 104. — Female pelvic organs in situ, seen from above. (Bardeleben.)
CRESCENTIC FRINGED BILABIAL BIPERFORATE CRIBRIFORM
FIG. 1105.— Varieties of hymen. (Testut, after Rose.)
The body of the clitoris, composed of erectile tissue, is about an inch and a quarter
in length, bent upon itself so that the angle opens downward. It tapers toward
the glans, is enclosed by a dense fibrous coat, and is divided by an incomplete
1494
THE FEMALE ORGANS OF GENERATION
septum corporum cavernosum into two semi-cylindrical corpora cavernosa clitoridis,
homologous with the corpora cavernosa of the male. A suspensory ligament passes
from the pubic symphysis to the fibrous coat of the body of the clitoris. Each
corpus cavernosum diverges from its fellow to form the crus clitoridis. Each crus
is attached to the pubic arch (pubis and ischium) and covered by the Ischio-
cavernosus muscle (m. erector clitoridis}.
To each crus of the clitoris goes a branch from the internal pudic artery, which
branch is known as the deep artery of the clitoris. The dorsal arteries of the clitoris
(arteriae dorsalis clitoridis) from the internal pudic send branches to the glans.
The nerves of the clitoris consist of the dorsal nerves of the clitoris from the internal
pudic nerve and sympathetic fibres from the hypogastric plexus.
SUSPENSORY LIGAMENT
OF CLITORIS
GLANS OF
CLITORIS
SPHINCTER
VAGINAE
MUSCLE
ERECTOR
CLITORIDIS
MUSCLE
ORIFICE OF
URETHRA
LABI A.
MINORA
CARUNCULAE
MYRTIFORMES
SPHINCTER
VAGINAE
MUSCLE
TRANSVERSE
PERINEI
MUSCLE
EXCRETORY
DUCT
GLAND OF
BARTHOLIN
OMPRESSOR
URETHRAE MUSCLE
TRANSVERSE
PERINEI MUSCLE
FIG. 1106. — The female external organs of generation dissected. (Spalteholz.)
The glans clitoridis is a minute mass of erectile tissue, surmounting the tapering
apex of the body of the clitoris. It is covered by a very sensitive epithelium, and
its erectile tissue, like that of the glans penis, is continuous with the erectile tissue
of the bulbus vestibuli, the homologue of the corpus spongiosum of the male. The
praeputium clitoridis and the frenulum clitoridis have already been described (p. 1491)
as divisions of the labia minora.
Arteries and Nerves of the Clitoris. — The body and the crura of the clitoris derive
their blood-supply from the deep artery of the clitoris (arteria pro/undo, clitoridis)
from the internal pudic artery. Another branch of this artery, the dorsal artery of
THE HYMEN 1495
the clitoris (arteria dorsalis clitoridis) supplies the glans. The nerve-supply is
derived from the dorsal nerve of the clitoris, from the internal pudic, and from the
hypogastric sympathetic plexus.
THE VAGINAL BULB (BULBUS VESTIBULI) (Fig. 1106).
The bulbus vestibuli may be regarded as the homologue of the bulb portions of
the corpus spongiosum of the male. The principal morphological difference lies
in the fact that the two halves are fused in the male, but remain separated in the
female. The bulbus vestibuli consists of a mass of minute convoluted blood-
vessels, of such plexiform arrangement as to be often called erectile tissue, arranged
in two halves on either side of the vaginal and urethral orifices. Each half is thicker
or more massive posteriorly, while anteriorly it is attenuated and joins its fellow
of the opposite side to form the pars intermedia, continuous with the erectile tissue
of the glans clitoridis. Each half of the bulbus vestibuli rests against the lateral
wall of the vagina and lies superficial to the triangular ligament. Externally and
inferiority it is covered by the Bulbo-cavernosus muscle.
Arteries and Nerves of the Bulbus Vestibuli. — The blood is supplied by the artery
to the bulb (arteria bulbi vestibuli) , a branch of the internal pudic artery. The nerve-
supply is by branches of the hypogastric sympathetic plexus.
GLANDS OF BARTHOLIN (GLANDULA VESTIBULARIS MAJOR
[BARTHOLINI]) (Fig. 1106).
On each side of the posterior part of the commencement of the vagina is a
round or oblong body, of a reddish-yellow color, and of the size of a horse-bean,
analogous to Cowper's gland in the male. It is called the gland of Bartholin, the
gland of Duverney, the vulvo-vaginal gland or the suburethral gland. Bartholin's
gland lies partly in the inferior or anterior leaf of the triangular ligament. The
posterior portion of the bulbus vestibuli and the Bulbo-cavernous muscle partly
cover it. Each gland opens by means of a long single duct immediately external
to the hymen, in the angle or groove between it and the nympha (Fig. 1105).
INTERNAL ORGANS (PARTES GENITALES INTERNAE MULIEBRES).
The internal organs of generation are — the vagina, the uterus and its appendages,
the Fallopian tubes, the ovaries and their ligaments.
THE VAGINA (Figs. 1100, 1103, 1109).
The vagina extends from the vulva to the uterus. It is situated in the cavity
of the pelvis, behind the bladder and in front of the rectum. Its direction is
curved upward and backward, at first in the line of the pelvic outlet, and afterward
in that of the axis of the cavity of the pelvis. Its walls are ordinarily in contact,
and its usual shape on transverse section is that of an H, the transverse limb
being slightly curved forward or backward, whilst the lateral limbs are somewhat,
convex toward the median line. Its length is about two and a half inches along
its anterior wall (paries anterior), and three and a half inches along its posterior
wall (paries posterior). It is constricted at its commencement, and becomes
dilated medially, and narrowed near its uterine extremity; it surrounds the vaginal
portion of the cervix uteri, a short distance from the os, its attachment extending
higher up on the posterior than on the anterior wall of the uterus (Fig. 1112).
1496 THE FEMALE ORGANS OF GENERATION
The vaginal axis forms with the uterine axis an obtuse angle opening forward,
and, as a rule, a little greater than a right angle (Fig. 1110). The fact that the
attachment of the vagina to the cervix is above the external os causes the forma-
tion of a recess between the cervix and vaginal wall, known as the vaginal fornix
(fornix vaginae). This recess is deeper posteriorly than it is laterally or in front.
The anterior portion of the fornix is called the anterior fornix (Fig. 1103).
The posterior portion is called the posterior fornix (Fig. 1103). The right and
left portions are called the right and left lateral fcrnices. The vagina opens into
the uro-genital cleft, between the labia minora and back of the urethra and
clitoris. It opens by the vaginal orifice (orificium vaginae) (Fig. 1102). In the
virgin the opening is partly closed by the hymen (p. 1492). After rupture
of the hymen atrophied fragments of the torn membrane remain around
the vaginal orifice, and are known as the carunculae myrtifcrmes (carunculae
hymenales).
Relations (Figs. 1100 and 1103). — The upper part of the anterior wall of the
vagina is in relation with the base of the bladder, being separated from that viscus
by lax connective tissue. Lower down the middle line of the anterior wall and
closely joined to it is the urethra. The upper part of the posterior wall, near
the middle line, is covered for a quarter of an inch or more with peritoneum,
which forms the anterior wall of the depths of the recto-vaginal pouch of perito-
neum or pouch of Douglas (excavatio rectouterina [Douglasi]) (Fig. 1112), between
the uterus and vagina and the rectum. The portion of the posterior wall below
the level of the pouch of Douglas is placed close to the rectum, a layer of pelvic
fascia intervening. As the vaginal orifice is neared, the rectum and vagina
separate, and interposed between them is a mass of fibro-fatty tissue called the
perinaeum or perineal body. Its sides are enclosed between the Levatores ani
muscles. The ureter toward its termination (Fig. 1113) lies near the lateral wall
of the vagina, passing at this point in a direction downward, inward, and slightly
forward to reach the bladder. The vagina near its termination passes through
the triangular ligament, and upon its sides are the bulbs of the vestibule, the
glands of Bartholin, and the Bulbo-cavernous muscle.
Structure. — The vagina consists of an internal mucous lining, of a muscular coat,
and between the two of a layer of erectile tissue.
The Mucous Membrane (tunica mucosa) (Fig. 1109). — The mucous membrane is
continuous above with that lining the uterus. Its inner surface presents, along
the anterior and posterior walls, a longitudinal ridge or raphe, called the rugous
columns of the vagina (columna rugarum anterior el posterior). The anterior col-
umn extends downward as far as the external orifice of the urethra, forming the
carina urethralis vaginae. Numerous transverse ridges or rugae (rugae vaginales)
extend outward from the raphe on either side. These rugae are divided by fur-
rows of variable depth, giving to the mucous membrane the appearance of being
studded over with conical projections or papillae; they are most numerous near
the orifice of the vagina, especially in females before parturition. The epithelium
covering the mucous membrane is of the squamous variety. The submucous tissue
is very loose and contains numerous large veins, which by their anastomoses
form a plexus, together with smooth muscular fibres from the muscular coat; it
is regarded by Gussenbauer as an erectile tissue (see p. 1497). It contains a
number of mucous crypts, but no true glands.
The Muscular Coat (tunica muscularis). — The muscular coat consists of two
layers : an external longitudinal, which is far the stronger, and an internal circular
layer. The longitudinal fibres are continuous with the superficial muscular fibres
of the uterus. The strongest fasciculi are those attached to the recto-vesical fascia
on each side. The two layers are not distinctly separable from each other, but
THE VAGINA
1497
are connected by oblique decussating fasciculi which pass from the one layer to
the other. Above the triangular ligament the fibres are non-striated ; in the region
of the ligament they show striations. In addition to this the vagina at its lower
end is surrounded by a band of striped muscular fibres, the sphincter vaginae
(p. 463). External to the muscular coat is a layer of connective tissue containing
a large plexus of blood-vessels.
The Erectile Tissue. — The erectile tissue consists of a layer of loose connective
tissue situated between the mucous membrane and the muscular coat; embedded
in it is a plexus of large veins, and numerous bundles of unstriped muscular fibres
derived from the circular muscular layer. The arrangement of the veins is
similar to that found in other erectile tissues.
EXTERNAL
ILIAC GLANDS
INTERNAL
ILIAC GLANDS
LATERAL
SACRAL GLANDS
AFFERENTS
TO EXTERNAL
ILIAC GLANDS
AFFERENTS
TO INTERNAL
LIAC GLANDS
RETROVAGINAL
NODULES
FIG. 1107. — The lymphatics of the vagina. Schematic. (Poirier and Charpy.)
Blood-vessels, Nerves, and Lymphatics. — The arteries of the vagina are branches
of the vesico- vaginal artery; the vaginal branch of the uterine artery (p. 688), and
branches of the internal pudic and middle haemorrhoidal. The veins form an abun-
dant plexus around the wall of the vagina and pass to the internal iliac veins. The
lymphatics (Fig. 1107) arise from two communicating networks, one of which is
below the mucous membrane, the other in the muscular wall. There is a third net-
work around the vaginal wall, from which the collectors arise. The trunks from the
upper third of the vagina pass to the external iliac glands; those from the middle
third pass to the internal iliac glands ; those from the lower third terminate in the
glands at the promontory of the sacrum or in the lateral sacral glands.1 The nerves
come from the third and fourth sacral nerves and from the utero-vaginal and
vesical plexuses of the sympathetic.
1 The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf.
1498
THE FEMALE ORGANS OF GENERATION
THE WOMB OR UTERUS (Figs. 1100, 1103, 1104, 1108, 1113).
The uterus is the organ of gestation, receiving the fecundated ovum in its cavity,
retaining and supporting it during the development of the foetus, and becoming
the principal agent in its expulsion at the time of parturition. It is a hollow
muscular organ. The non-pregnant uterus is contained in the cavity of the pelvis
between the bladder and rectum (Figs. 1103 and 1104). It is rarely placed exactly
in the mid-line, but inclines to one side or the other, more often to the left than
to the right. The walls of the organ are extremely thick. The uterus is movable
as a whole, and the body of the uterus is movable upon the neck. Its position
varies with the condition of adjacent parts, especially the bladder and rectum.
The cervix is more firmly fixed than the body and fundus, and hence the latter
vary more in position than the former. Normally, in an erect individual, with the
bladder and rectum empty, the external os is at the level of the upper surface of
the pubic symphysis (Fig. 1100) and in frontal plane passing through the ischiatic
spines. The long axis of the uterus is directed forward and upward (Fig. 1100),
and is angled where the body and cervix join. Hence, normally, with the bladder
ANTERIOR ISTHMUS OF
BORDER OF FALLOPIAN
MESOVARIUM OVARY TUBE
FALLOPIAN
TUBE
MCSOSALPINX
OVARIAN
FIMBRIA
ABDOMINAL
ORIFICE
FIMBRIAE OF
FALLOPIAN TUBE
OVARIAN ARTERY
AND VEIN
TUBAL
EXTREMITY
OF OVARY UTERINE
EXTREMITY
OF OVARY
FORNIX OF
VAGINA
VAGINAL
PORTION OF
CERVIX
ANTERIOR LIP
OF CERVIX
FIG. 1108. — The uterus, the left Fallopian tube and the left ovary in their connection -with the broad ligament of
the uterus, which has been fully unfolded. Seen from behind. From a virgin, aged nineteen years. (Toldt.)
empty, the uterus is anteverted and anteflexed. When the bladder fills the ante-
version and anteflexion are almost abolished. If the bladder is overdistended and
the rectum is empty, the uterus is pushed strongly backward, so that its long axis
corresponds to the long axis of the vagina; in other words, it is retroverted.
In the virgin state it is pear-shaped, flattened from before backward, and
is retained in its position by the round and broad ligaments on each side, and
projects into the upper end of the vagina below (Figs. 1108 and 1109). Its upper
end, or base, is directed upward and forward; its lower end, or apex, downward
and backward, in the line of the axis of the inlet of the pelvis. It therefore
forms an angle with the vagina, since the direction of the vagina corresponds to
the axis of the cavity and outlet of the pelvis. The non-pregnant adult uterus
measures about three inches in length, two inches in breadth at its upper part, and
nearly ait inch in thickness, and it weighs from an ounce to an ounce and a half.
It consists of two parts (Fig. 1108): (1) An upper and larger portion, consisting
of the body and fundus. This portion is flattened from before backward. (2) A
lower, smaller, and cylindrical portion, the cervix.
THE WOMB OR UTERUS
1499
The Fundus (fundus uteri) (Fig. 1108). — The funclus is the upper broad
extremity of the uterus. If a line is drawn from the uterine opening of one
Fallopian tube to the other, the portion above the line is the fundus. The
fundus is directly continuous with the body.
The Body of the Uterus (corpus uteri) (Fig. 1108). — The body of the uterus is
below and continuous with the fundus. In outline, when seen from in front or
behind, it resembles a triangle, the base being above and the point being absent.
PREPUCE OF
CLITORIS
CLANS
CLITORIOIS
EXTERNAL
ORIFICE OF
URETHRA
PARA-URETHRAL
DUCT
ORIFICE OF
DUCT OF
BARTHOLIN'S
GLAND
BARTHOLIN'S
'GLAND
ANTERIOR
VAGINAL
COLUMN
TRANSVERS
RUGAE
VAGINAL
FORNIX
VAGINAL
PORTION OF
CERVIX
MUSCULAR
COAT
ANTERIOR
WALL
ANTERIOR
LIP OF
CERVIX
OS UTERI
EXTERNUM
POSTERIOR
LIP OF
CERVIX
SUPRAVAGINAL
PORTION
CERVIX
Fio. 1109. — The female external genital organs of a virgin attached to the vagina, which has been isolated
and opened, and a portion of the cervix uteri. (Toldt.)
The anterior surface (fades vesicalis) passes on each side into the posterior surface
(fades intestinalis) by the lateral border (margo lateralis).
The body gradually narrows from the fundus to'the neck. Its anterior surface is
so slightly rounded as to appear flattened. It is covered by peritoneum (Fig. 1108),
which becomes separated from it at its union with the cervix, in order to form the
utero-vesical pouch, which lies between the uterus and bladder (Fig. 1112). Its pos-
terior surface is more rounded than the anterior, being convex transversely. It is
1500
THE FEMALE ORGANS OF GENERATION
covered by peritoneum throughout (Fig. 1113), and separated from the rectum by
some convolutions of the small intestine (Fig. 1 102). The peritoneum which covers
the posterior surface forms most of the anterior wall of Douglas' cul-de-sac (Figs.
866, 1112, and 1113, and p. 1258). Its lateral margins (Figs. 1108 and 1113) are
concave, and each gives attachment to the Fallopian tube above, the round ligament
below, and in front of this the ligament of the ovary; behind both of these struc-
tures, and from the side of the womb the broad ligament passes. The division
GARTNER'S
"DUCT
FIG. 1110. — The parovarium. The mesosalpinx is partly removed. (Poirier and Charpy.)
between the body and the cervix is indicated externally by a slight constriction, and
by the reflection ^of the peritoneum from the anterior surface of the uterus on to the
bladder, and internally by a narrowing of the canal called the internal os (Fig. 1111).
The Neck or Cervix Uteri (Figs. 1108 and 1111). — The neck or cervix uteri is
the lower constricted segment of the uterus; around its circumference is attached
the upper end of the vagina (Figs. 1103, 1108, 1109, and 1112), which extends
upward a greater distance behind than in front. The neck is spindle-shaped in
those who have had no children, cylindrical in those who have had children.
UTERINE
ORIFICE OF
FALLOPIAN TUBE
O K
C <
MESOSALPINX U O
ISTHMUS OF
UTERINE FALLOPIAN
PORTION OF TUBE
FALLOPIAN TUBE
LONGITUDINAL
O O < FOLDS
EPOOPHORON
ABDOMINAL
/ORIFICE
HYDATID OF
MOROAGNI
UTEROVAQINAL
VENOUS
PLEXUS
SVAGINAL
FORNIX
OS UTERI
EXTERNUM
FIG. 1111.— The uterus and the right Fallopian tube opened from behind. (Toldt.)
The Supravaginal Portion (portio supravaginalis [cervicis]) (Figs. 1108 and 1112).
— The supravaginal portion is not covered by peritoneum in front; a pad of cellular
tissue is interposed between it and the bladder. Behind, the peritoneum is extended
over it.
The Vaginal Portion (portio vaginalis [cervicis]) (Figs. 1103, 1108, 11 09, and 1
— The vaginal portion is the lower end projecting into the vagina. It is round or
THE WOMB OR UTERUS
1501
elliptical, the long axis of the elliptical figure being transversely placed. On its
surface is a small aperture, the external mouth of the womb, or os uteri, or external os
(orificium externum uteri) (Figs. 1108, 1109, 1111, and 1112), generally circular in
shape, but sometimes oval or almost linear. If a woman has borne children the
opening is transverse and the margins are irregular. The margin of the opening is,
in the absence of past parturition or
disease, quite smooth. This aperture
divides the vaginal portion of the cervix
into two lips, an upper or posterior lip
(labium posterius) and a lower or an-
terior lip (labium anterius). On each
side of the cervix and upper portion of
the vagina there is a space containing
bloodvessels and filled with loose cellu-
lar tissue. This loose tissue passes
upward between the layers of the broad
ligament and is called parametrium.
On each side of the cervix and three-
quarters of an inch away is the termi-
nal portion of the corresponding ureter.
Folds and Ligaments. — The liga-
ments of the uterus are eight in number. Some are simple folds of peritoneum;
others contain connective tissue and muscle. The ligaments are as follows : one
RECTAL PERITONEUM
OVAGINAL POUCH
INTERIOR AND POS-
TERIOR LAYERS OF
BROAD LIGAMENT
VESICAL
PERITONEUM
UTERO-VCSICAL
POUCH
SUPRA-VAGINAL
PORTION OF
CERVIX
FIG. 1112. — The cervix uteri and upper end of the
vagina, showing their relations to the peritoneum.
Diagrammatic. (Testut.)
ROUND
.ICAMENT.
nal iliac
artery.
Apex of Douglas's
pouch.
External
artery.
FIG. 1113. — Douglas's pouch. (From a preparation in the Museum of the Royal College of Surgeons of England.)
anterior, one posterior, two lateral or broad, two sacro-uterine — all these being formed
of peritoneum — and, lastly, two round ligaments.
1502
THE FEMALE ORGANS OF GENERATION
The Anterior Ligament or the Utero-vesical Fold or Vesico-uterine Ligament is
reflected on to the bladder from the front of the uterus, at the junction of the
cervix and body. It forms the utero-vesical pouch (excavatio vesicouterina) (Figs.
1112andlll3).
The Posterior Ligament or the Recto-vaginal Fold passes from the posterior wall
of the uterus over the upper fourth of the vagina, and thence on to the rectum and
sacrum. It thus forms a pouch, called the recto-vaginal pouch or Douglas' pouch
(Figs. 8G6, 1112, and 1113), the boundaries of which are, in front, the posterior
wall of the uterus, the supravaginal portion of the cervix, and the upper fourth of
the vagina; behind, the rectum and sacrum; above, the small intestine; and,
laterally, the folds of Douglas or recto-uterine folds, which contain the sacro-
uterine ligaments.
The Lateral or Broad Ligament (ligamentum latum uteri) '(Figs. 1104, 1114,
and 1121) is a peritoneal fold which passes from each side of the uterus to the
lateral wall of the pelvis as high as the external iliac vein. From this region
comes the peritoneal fold called the suspensory ligament of the ovary (Fig. 1114).
The two broad ligaments form a septum across the pelvis, which divides that
cavity into two portions. In the anterior part are contained the bladder, urethra,
and vagina; in the posterior part, the rectum. In the uterus normally placed the
anterior surface of the broad ligament faces forward and downward, and the pos-
terior surface faces upward and backward. The ligament is more nearly vertical
FALLOPIAN
TUBE
CORPUS
ALBICANS
ESOSALPINX
SEROUS
MEMBRANE
GRAAFIAN
FOLLICLE
GRAAFIAN
FOLLICLE
STROMA Of
OVARY
LIGAMENT
31 OF OVARY
MESOMETRIUM'
FIG. 1114. — The broad ligament of the uterus, with
the mesoyarium, the mesosalpinx, the ovary, and
the Fallopian tube in transverse section. (Toldt.)
FIG. 1115. — Longitudinal section through the ovary.
(Toldt.)
at its pelvic insertion. The two layers of the broad ligament are mostly near
to each other, to the side and below they separate and pass into the peritoneum
of the lateral pelvic wall, the bladder and the rectum. Between the two layers
of each broad ligament are contained — (1) the Fallopian tube superiorly; (2) the
round ligament; (3) the ovary and its ligament; (4) the parovarium or organ of
Rosenmiiller, and the paro-ophoron ; (5) loose connective tissue, which is called
parametrium; (6) unstriped muscular fibre; and (7) blood-vessels and nerves. The
Fallopian tube is in the free edge of the broad ligament, and is contained in a
special fold, which is attached to the part of the ligament near the ovary, and is
known by the name of the mesosalpinx (Tigs. 1110, 1114, and 1121). If the
mesosalpinx is spread out, it is seen to be roughly triangular; the base of the
triangle is outward, the apex at the upper and outer angle of the uterus; the
upper boundary is the Fallopian tube, and the lower boundary is the ovary and
its ligament. Between the two layers of the mesosalpinx are the parovarium and
the paro-ophoron. Between the fimbriated extremity of the tube and the lower
attachment of the broad ligament is a concave rounded margin, called the infun-
dibulo-pelvic ligament (Fig. 1120).
THE WOMB OR UTERUS 1503
The ovary lies in a depression of the broad ligament called the ovarian bursa
(bursa ovarii) (Figs. 1114 and 1121), and is joined to the ligament by a short fold,
the mesovarium (Fig. 1121).
The mesovarium passes upward from the posterior surface of the broad liga-
ment (Fig. 1114). Beneath the mesovarium is a larger and thicker portion of
the broad ligament, called the mesometrium (Fig. 1114).
The Sacro-uterine or Utero-sacral Ligaments (plicae rectouterinae) are contained
in the peritoneal folds of Douglas. They pass from the second and third bones
of the sacrum, downward and forward on the lateral aspects of the rectum to be
attached one on each side of the uterus at the junction of the supravaginal cervix
and the body, this point corresponding internally to the position of the os
internum. They contain fibrous tissue and unstriated muscle-fibre. Muscular
fibres from the uterine wall to the rectal wall constitute the Recto-uterinus muscle
(musciilus rectouterinus). This muscle is part of the sacro-uterine ligaments.
A Round Ligament (ligamentum teres uteri) (Figs. 1104, 1113, 1116, and 1121) is
attached on each side of the uterus. The two ligaments are rounded cords
between four and five inches in length, each situated between the layers of the
broad ligament in front of and below the Fallopian tube. Commencing at the
superior angle of the uterus, this ligament passes forward, upward, and outward
through the internal abdominal ring, along the inguinal canal, to the labium
majus, in which it becomes lost. The round ligament consists principally of
muscular tissue prolonged from the uterus; also of some fibrous and areolar tissue,
besides blood-vessels and nerves, enclosed in a duplicature of peritoneum, which
in the foetus is prolonged in the form of a tubular process for a short distance into
the inguinal canal. This process is called the canal of Nuck. It is generally oblit-
erated in the adult, but sometimes remains pervious even in advanced life. It
is analogous to the peritoneal pouch which precedes the descent of the testis.
The Cavity of the Uterus (cavum uteri] (Fig. 1111). — The cavity of the uterus
is small in comparison with the size of the organ, because of the great thickness of
the wall. That portion of the cavity which corresponds to the body is triangular,
flattened from before backward, so that its anterior and posterior walls are closely
approximated, and having its base directed upward toward the fundus. At each
superior angle is a funnel-shaped cavity, which constitutes the remains of one
division of the body of the uterus into two cornua, and at the bottom of each cavity
is the minute orifice of the Fallopian tube. At the inferior angle of the uterine
cavity is a small constricted opening, smaller and more nearly circular than the
external os uteri, the internal orifice of the uterus or internal os uteri (orificium
internum uteri) (Fig. 1111), which leads into the cavity of the cervix.
The Cavity of the Cervix or Cervical Canal (canalis cervicis uteri) (Fig. 1111).
—The cavity of the cervix or cervical canal extends from the internal os uteri to
the external os uteri. It" is somewhat fusiform, flattened from before backward,
broader at the middle than at either extremity, and communicates below with the
vagina. The wall of the canal presents, anteriorly and posteriorly, a longitudinal
column, from which proceed a number of small oblique columns, giving the appear-
ance of branches from the stem of a tree; and hence the name uterine arbor vitae
(plicae palmatae) applied to it. These folds usually become very indistinct after
the first labor.
Structure. — The uterus is composed of three coats: an external or serous coat, a
middle or muscular coat, and an internal or mucous coat.
The Serous Coat or Perimetrium (tunica serosa) (Figs. 1103, 1108, 1112, and 1113).
—The serous coat is derived from the peritoneum; it invests the fundus and the
whole of the posterior surface of the uterus; but covers the anterior surface only as
far as the junction of the body and cervix. In the lower fourth of the posterior
surface the peritoneum, though covering the uterus, is not closely connected with
1504 THE FEMALE ORGANS OF GENERATION
it, being separated from it by a layer of loose cellular tissue and some large veins.
At the lateral margins of the uterus the serous coat passes on to the broad liga-
ments. The serous coat adheres closely to the uterus, and it is very difficult to
separate it from the muscle.
The Muscular Coat (tunica muscularis} (Fig. 1111) .—The muscular coat forms the
chief bulk of the substance of the uterus. In the unimpregnated state it is dense,
firm, of a grayish color, and cutsalmost like cartilage. It is thick opposite the middle
of the body and fundus, and thin at the orifices of the Fallopian tubes. It consists
of bundles of unstriped muscular fibres, disposed in layers, intermixed with areolar
tissue, blood-vessels, lymphatic vessels, and nerves. The muscular tissue is dis-
posed in three layers — external, middle, and internal.
The external layer is placed beneath the peritoneum, disposed as a thin plane
on the anterior and posterior surfaces. It consists of fibres which pass trans-
versely across the fundus, and, converging at each superior angle of the uterus,
are continued on the Fallopian tube, the round ligament, the ligament of the
ovary; some passing at each side into the broad ligament, and others running
backward from the cervix into the sacro-uterine ligaments. The fibres of the
external portion of the outer layer (stratum subserosum) are longitudinal. The
fibres of the inner portion of the outer layer (stratum supravasculare) are partly
circular and partly longitudinal.
The middle layer of fibres (stratum vasculare), which is thickest, presents bundles
of circular fibres closely connected with blood-vessels. In this layer are most of
the blood-vessels. The circular fibres about the internal os form a distinct
sphincter. Those which surround the orifices of the Fallopian tubes are arranged
in the form of two hollow cones, the apices of which surround the orifices of the
Fallopian tubes, their bases intermingling with one another on the middle of the
body of the uterus.
The internal or deep layer (stratum mucosum) consists of longitudinal fibres.
Some consider the deeper portion of the muscular tissue of the uterus to be the
muscularis mucosae. But the deep portion of the muscular substance is con-
tinuous with the more superficial portion, and there is no submucous coat between
the muscle and the mucous membrane. The deeper layer of muscular fibres of
the uterus contains connective tissue and elastic fibres. The muscular tissue of
the cervix contains more connective and elastic tissue than does the body of the
uterus; hence, the cervix is harder and stiffer than the body.
The Mucous Membrane (tunica mucosa) (Fig. 1111). — The mucous membrane
is thin, smooth, and closely adherent to the subjacent muscular tissue. .It is
continuous, through the fimbriated extremity of the Fallopian tubes, with the
peritoneum, and through the os uteri with the lining of the vagina.
In the body of the uterus it is smooth, soft, of a pale-red color lined with columnar
ciliated epithelium, and presents, when viewed with a lens, the orifices of numer-
ous tubular follicles arranged perpendicularly to the surface. It is unprovided
with any submucosa, but is intimately connected with the innermost layer of
the muscular coat. In structure its corium differs from ordinary mucous membrane,
consisting of an embryonic nucleated and highly cellular form of connective tissue,
in which run numerous large lymphatics. In it are the tube-like uterine glands
(glandulae uterinae), which are of small size in the unimpregnated uterus, but
shortly after impregnation become enlarged and elongated , presenting a contorted
or waved appearance toward their closed extremities, which reach into the mus-
cularis, and may be single or bifid. The uterine glands consist of a delicate
membrane, lined with epithelium, which becomes ciliated toward the orifices.
In the cervix the mucous membrane is sharply differentiated from that of the
uterine cavity. It is thrown into numerous oblique ridges, which diverge from an
anterior and posterior longitudinal raphe, presenting an appearance which has
1505
received the name of arbor vitae. In the upper two-thirds of the canal the mucous
membrane is provided with numerous deep glandular follicles (glandulae cervicales
uteri), which secrete a clear viscid alkaline mucus; arid in addition, extending
through the whole length of the canal, are a variable number of little cysts, pre-
sumably follicles, which have become occluded and distended with retained secre-
tion. They are called the ovules of Naboth. The mucous membrane covering the
lower half of the cervical canal presents numerous papillae. The epithelium of
the upper two-thirds is cylindrical and ciliated, but below this it loses its cilia, and
gradually changes to squamous epithelium close to the external os.
The Uterus at Different Ages. — The uterus of the foetus is in the abdominal cavity
projecting above the brim of the pelvis. The cervix is considerably larger than
the body. At birth the cervix is larger relatively than in the adult; there is no dis-
tinct internal os distinguish ing the cavity of the body of the uterus from the cavity of
the cervix, and " the arbor vitae extends throughout the whole length of the uterus."1
The growth of the uterus is slow until puberty is almost reached, when for a time
the growth is rapid. The growth of the uterine body causes the mucous mem-
brane of this part to lose its folds, hence the arbor vitae disappears from the body.
In a wroman who has had children .the uterine cavity is larger than in a woman
who has never borne a child. In advanced years the uterine wall becomes paler
and hard and rigid from atrophic fibrous changes. A more distinct constriction
separates the body and cervix. The internal os frequently and the external os
occasionally are obliterated in old age.
Abnormalities. — Very rarely the uterine cavity is divided into two by a septum.
Occasionally the condition known as bicornate uterus exists. In this condition
each lateral angle is prolonged into a horn or cornu. The uterus is formed by the
union of the two ducts of Miiller, and failure of fusion of these ducts makes a
double uterus or a bicornate uterus.
Changes at a Menstrual Period. — For several days before the menstrual flow
begins the mucous membrane increases in thickness and vascularity and its sur-
face is cast into folds. After these preparatory changes the superficial portions
of the mucous membrane break down and are cast off, and bleeding begins. At
the termination of menstruation the mucous membrane rapidly regenerates. At
each menstrual period from 100 to 200 grammes of blood are discharged. The
meaning of menstruation is uncertain. Pfliiger believes the wall of the uterus is
made raw, so that if an impregnated ovum arrives it will adhere. Reichert believes
that menstruation means that no impregnated ovum has arrived in the womb, and
hence no bed is needed for one.
Changes Induced by Pregnancy. — The muscular fibres hypertrophy enormously
and become vastly longer and broader. There is a great increase in connective
tissue, and new connective-tissue fibres pass between bundles of muscle. The
peritoneal coat undergoes hyperplasia. It remains closely adherent to the uterus,
except over the lower segment, from which region it can be easily stripped. The
blood-vessels become large and tortuous. The nerves are increased in length and
new filaments form. The lymphatics undergo hypertrophy and hyperplasia
(Prof. Barton Cooke Hirst). The uterus becomes spherical, and after the fourth
month ovoidal. Early in pregnancy the increase in weight causes the uterus
to descend in the pelvis. After the third month it rises progressively, and during
the ninth month the fund us reaches the epigastrium. " Before term (four weeks
in primiparae, ten days or one week in multiparae) the fund us sinks again, as
the presenting part and lower uterine segment become engaged in the pelvic
cavity. This phenomenon is explained by contraction of the overstretched
abdominal walls."2 The womb is acutely anteflexed during the first three months
1 Prof. Francis A. Dixon in Prof. Cunningham's Text-book of Anatomy.
8 A Text-book of Obstetrics. By Prof. Barton Cooke Hirst.
95
1506
THE FEMALE ORGANS OF GENERATION
of pregnancy. After this period, as the womb rises, the anteflexion is diminished,
but some degree remains, because the abdominal walls are too lax to hold the
organ straight. The uterus passes somewhat to the right side and undergoes a
rotation on its longitudinal axis, so that the anterior surface looks front and to the
^~~Z^*sss**^>^ Branches to tube.
Branches to f undue.
Ovarian artery
Branch to round ligament.
ROUND LIGAMENT.
Uterine artery.
Arteries of cervix.
Vaginal arteries.
FIG. 1116. — The arteries of the internal organs of generation of the female, seen from behind. (After Hyrtl.)
right. These changes in position are caused by fecal distention of the sigmoid.
The intestines are above and back of the uterus. During the first four months the
cervix softens and enlarges somewhat. The length of the cervical canal is not
VESSELS FROM
BODY OF FUNDUS
VESSELS
FROM TUBE
ANASTOMOSIS
OF VESSELS
VESSELS OF
ROUND LIGAMENT
VAGINAL
LYMPHATICS
FIG. 11 17. ^The lymphatic vessels of the uterus. (Poirier and Charpy.)
altered during pregnancy, and the canal does not dilate until labor begins. During
pregnancy the cervical glands secrete thick mucus, which coagulates and occludes
the cervical canal ; the round ligaments become stronger, and the layers of the
broad ligament are separated toward their inner portions by the enlarging womb.
THE WOMB OR UTERUS
1507
After parturition the uterus nearly regains its former size, usually weighing
something over one and a half ounces; but its cavity is larger than in the virgin
state, the external orifice is more marked, its edges present a fissured surface, its
vessels are very tortuous, and its muscular layers are more defined.
Vessels and Nerves (Fig. 1116). — The arteries of the uterus are the uterine, from
the internal iliac, and the ovarian, from the aorta. They are remarkable for their
tortuous course in the substance of the organ and for their frequent anastomoses.
The uterine artery reaches the lower part of the uterus at the side and is. pro-
JUXTA-AORTIC
GLANDS
VESSELS FROM
BODY OF UTERUS
VESSELS FROM
NECK OF UTERUS
TO LATERAL
SACRAL GLAND
VESSELS FROM
NECK OF UTERUS
VESSELS OF
ROUND LIGAMENT
JUXTA-AORTIC
GLANDS
VESSEL OF
FALLOPIAN TUBE
UTERUS
FIG. 1118. — The lymphatics of the internal organs of generation in the female. (Poirier and Charpy.)
longed as a large artery to the body and fundus, which ascends between the
layers of the broad ligament. The uterine artery gives off a smaller branch, the
cervical, which descends to supply the cervix and sends cervico-vaginal branches
to the vagina. The azygos arteries of the vagina come from the cervico-vaginal
reinforced by branches of the vaginal arteries (Fig. 1121). A median longitu-
dinal vessel is formed in front and behind, which descends in the vaginal wall.
The termination of the ovarian artery meets the termination of the uterine
artery, and forms an anastomotic trunk from which branches are given off to
supply the uterus. Dr. Robinson, instead of describing the uterine and ovarian
1508
THE FEMALE ORGANS OF GENERATION
arteries as two vessels, describes them as parts of one vessel, the arteria uterina
ovarica (p. 689). The veins are of large size, and correspond with the arteries.
In the impregnated uterus these vessels form the uterine sinuses, consisting of
the lining membrane of the veins adhering to the walls of the canals channelled
through the substance of the uterus. They terminate in the uterine plexuses,
which empty into the internal iliac veins. The lymphatics (Figs. 1117 and 1118)
originate from three networks, a muscular network, a peritoneal network, and a
network in the stroma. The trunks from these networks anastomose, and thus
form another network beneath the peritoneum, and from the fourth network the
collectors arise. The network of the cervix is continuous with that of the body.
The collecting trunks from the cervical region number from five to eight. Some
terminate in the external iliac glands, some in the internal iliac glands, some in the
lateral sacral glands, or the glands of the promontory. The collecting trunks from
the body terminate chiefly in the juxta-aortic or pre-aortic glands, but some termi-
nate in the external iliac glands, and some in the inguinal glands.1 The nerves come
chiefly from the utero-vaginal plexus, which continues into the hypogastric plexus
and receives filaments from the third and fourth sacral nerves. The uterus also
receives direct fibres from the hypogastric plexus and from the vesical plexus.
FIG. 1119. — Relations between uterus, ureter, and uterine artery. (Schematic.)
Surgical Anatomy.— Pelvic cellulitis (parametritis) is inflammation of the pelvic cellular
tissue. It is due to sepsis, and its usual antecedent is uterine sepsis. A laceration of the cervix
may admit bacteria. An abscess may form. If it points in the vagina it should be incised through
the vaginal wall. The uterus may require removal (hysterectomy} in cases of malignant disease
or for fibroid tumors. Carcinoma is the most common form of malignant disease of the uterus,
though cases of sarcoma do occur. Carcinoma may show itself either as a columnar carcinoma
or as a squamous carcinoma ; the former commencing either in the cervix or body of the uterus, the
latter always commencing in the epithelial cells of the mucous membrane covering of the vaginal
surface of the cervix. The columnar form may be treated in the early stage, before fixation has
taken place, by removal of the uterus, either through the vagina or by means of abdominal
section. The former operation is attended by the smaller death-rate. Vaginal hysterectomy
may be performed in any case in which the uterus or the uterus and tumor are not too large to be
withdrawn through the vagina. It is difficult in this operation to deal with adhesions and other
complications in the upper part of the pelvis, and for this reason many surgeons prefer the abdom-
inal operation. Vaginal hysterectomy is performed by placing the patient in the lithotomy position
and introducing a large duckbill speculum into the vagina. The cervix is then seized with a vol-
sellum and pulled down as far as possible and the mucous membrane of the vagina incised around
the cervix as near to it as the disease will allow, especially in front, where the ureters are in
danger of being wounded. A pair of dressing forceps are then pushed through into Douglas's
1 The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf.
THE ADNEXA OR APPENDAGES OF THE UTERUS 1509
pouch and opened sufficiently to allow of the introduction of the two forefingers, by means of
which the opening is dilated laterally as far as the sacro-uterine ligaments. A somewhat similar
proceeding is adopted in front, but here the bladder has to be separated from the anterior wall
of the uterus for about an inch before the vesico-uterine fold of peritoneum can be reached.
This is done by carefully burrowing upward with a director and stripping the tissues off the
anterior uterine wall. When the vesico-uterine pouch has been opened and the opening dilated
laterally, the uterus remains attached only by the broad ligaments, in which are contained the
vessels that supply the uterus. Before division of the ligaments, these vessels have to be dealt
with. The forefinger of the left hand is introduced into Douglas's pouch and an aneurism
needle, armed with a long silk ligature, is inserted into the vesico-uterine pouch, and is pushed
through the broad ligament of one side about an inch above its lower level and at some distance
from the uterus. One end of the ligature is now pulled through the anterior opening, and in this
way we have the lowest inch of the broad ligament, in which is contained the uterine artery,
enclosed in a ligature. This is tied tightly, and the operation is repeated on the other side. The
broad ligament is then divided on either side, between the ligature and the uterus, to the extent
to which it has been constricted. By traction on the volsellum which grasps the cervix, the uterus
can be pulled considerably farther down in the vagina, and a second inch of the broad ligament
is treated in a similar way. This second ligature will embrace the pampiniform plexus of veins
and, when the broad ligament has been divided on either side, it will be found that a third liga-
ture can be made to pass over the Fallopian tube and top of the broad ligament, after the uterus
has been dragged down as far as possible. After the third ligature has been tied and the struc-
tures between it and the uterus divided, this organ will be freed from all its connections and can
be removed from the vagina. This canal is then sponged out and lightly dressed with gauze,
no sutures being used. The gauze may be removed at the end of the second day. In squamous
epithelioma, amputation of the cervix is done by some in those cases where the disease is recog-
nized before it has invaded the walls of the vagina or the neighboring broad ligaments. The
operation consists in removing a wedge-shaped piece of the uterus, including the cervix, through
the vagina and attaching the cut surfaces of the stump to the anterior and posterior vaginal walls,
so as to prevent retraction. In view, however, of the continuity of the lymphatic network of the
cervix with the lymphatics of the body, the operation is insufficient and should be condemned.
Complete abdominal hysterectomy is rarely necessary, except for malignant disease. In this opera-
tion the entire uterus is removed. The preliminary introduction of bougies into the ureters as
practised by Kelly and Clark enables the surgeon to readily recognize the situations of these tubes.
After the abdomen has been opened the uterine vessels are secured and the broad ligaments
divided in a similar manner to that employed in vaginal hysterectomy, except that the proceeding
is commenced from above. When the first two ligatures have been tied and the broad ligament
divided, it will be found that the uterus can be raised out of the pelvis. A transverse incision
is now made through the peritoneum, where it is reflected from the anterior surface of the uterus
on to the back of the bladder and the serous membrane peeled from the surface of the uterus
until the vagina is reached. The anterior wall of this canal is cut across. The uterus is now
turned forward and the peritoneum at the bottom of Douglas's pouch incised transversely, and
the posterior wall of the vagina cut across until it meets the incision on the anterior wall. The
uterus is now almost free, and is held only by the lower part of the broad ligament on either
side, containing the uterine artery. A third ligature is made to encircle this, and, after having
been tied, the structures are divided between the ligature and the uterus. The organ can now
be removed. The vagina is plugged with gauze, and the external wound closed in the usual
way. The vagina acts as a drain, and therefore the opening into it is usually left unsutured. In
some cases of uterine fibroid the abdomen is opened and the tumor is removed, but the uterus is
not taken away. This operation is called myomectomy. This operation is suited only to solitary
subperitoneal or interstitial tumors (Penrose).
The common operation for uterine fibroids is supravaginal amputation. The uterus is
cut away and the cervical flaps are sutured. Before the technique of hysterectomy was per-
fected and before myomectomy was devised the favorite operation for uterine fibroids was
salpinfjo-odphorectomy, and by it a large majority of cases operated upon were cured. W7hen it
succeeds a premature menopause is induced and the tumor shrinks. The operation is useless if
a woman is past the menopause, and is apt to fail if the tumor is very soft or very large.
THE ADNEXA OR APPENDAGES OF THE UTERUS.
The appendages of the uterus are the Fallopian tubes, the ovaries and ovarian
ligaments, and the round ligaments. They are placed in the following order: in
front is the round ligament; the Fallopian tube occupies the upper margin of the
broad ligament; the ovary and its ligament are behind and below both.
1510 THE FEMALE ORGANS OF GENERATION
THE FALLOPIAN TUBE (TUBA UTERINA [FALLOPII])
(Figs. 1108, 1113, 1114, 1120, 1121).
The Fallopian tubes or oviducts convey the ova from the ovaries to the cavity
of the uterus. They are two in number, one on each side, situated in the upper
margin of the broad ligament, extending from each superior angle of the uterus to
the sides of the pelvis. Each tube is about four inches and a quarter in length,
and is placed in a fold of peritoneum, which is part of the broad ligament and is
called the mesosalpinx (Fig. 1114). Each tube is described as consisting of four
portions: (1) the isthmus (isthmus tub ae uterinae) (Fig. 1120), or inner constricted
third ; (2) the ampulla (ampulla tubae uterinae) (Fig. 1 120) , or outer dilated portion,
which curves over the ovary; and (3) the infundibulum (infundibulum tubae uter-
inae), the funnel-like expansion of the tube, at the bottom of which is the abdominal
orifice or pavilion (ostium abdominale tubae uterinae) (Fig. 1120). The abdominal
orifice has a small diameter (2 mm. when relaxed to its full extent). The margin of
the infundibulum is rendered irregular by the presence of numerous small pro-
cesses, the fimbriae (fimbriae tubae). This end of the tube is called the fimbriated
extremity (Fig. 1120), because of these processes. The surfaces of the fimbriae
looking into the cavity of the infundibulum are covered with mucous membrane
continuous with the tubal mucous membrane. The outer surfaces are covered with
peritoneum. One of the fimbriae is attached to the ovary and is called the ovarian
fimbria (fimbria ovarica) (Fig. 1120). (4) The uterine portion of the tube (pars
uterina) (Fig. 1111) is in the uterine wall. The opening into the uterus (ostium
uterinum tubae) is even smaller than the abdominal opening, and will admit only a
small bristle. The general direction of the Fallopian tube is outward, backward,
and downward. In connection with the fimbriae of the Fallopian tube or with the
broad ligament close to them there is frequently one or more small vesicles floating
on a long stalk of peritoneum. These are termed the hydatids of Morgagni (appen-
dices vesiculosi). They are representative of small portions of the upper extremity
of the Wolffian duct.
Course Pursued by the Fallopian Tube (Figs. 1104 and 1120). — The tube on each
side begins at the upper and outer angle of the uterus and passes outward in a
horizontal direction toward the uterine extremity of the ovary. It then bends
almost to a right angle and ascends close to the pelvic wall and in front of the
anterior margin to the tubal extremity of the ovary. At this point it turns sharply
downward and a little backward, and the inner surface of the infundibulum comes
to lie upon the free margin and the posterior portion of the inner surface of the
ovary. "The fimbria ovarica thus ascends in a recurrent direction to the extrem-
itas tubaria."1
Structure. — The Fallopian tube consists of three coats — serous, muscular, and
mucous.
The external or serous coat (tunica serosa) (Fig. 1115) is peritoneal. Beneath
this lies the tunica adventitia, composed of lax connective tissue.
The middle or muscular coat (tunica muscularis) consists of an external longi-
tudinal layer (stratum longitudinale) , and an internal circular layer (stratum cir-
cular e) of muscular fibres continuous writh those of the uterus.
The internal or mucous coat (tunica mucosa) is continuous with the mucous lining
of the uterus and, at the free extremity of the tube, with the peritoneum. It is
thrown into longitudinal folds (plicae tubariae), which in the outer, larger part of
the tube or ampulla (plicae ampullares) are much more extensive than in the
narrow canal of the isthmus (plicae isthmicae). The lining epithelium is columnar
and ciliated. This form of ephithelium is also found on the inner surface of the
1 Spalteholz's Atlas. English edition by Barker.
THE FALLOPIAN TUBE
1511
fimbriae, while on the outer or serous surfaces. of these processes the epithelium
gradually merges into the endothelium of the peritoneum.
Vessels and Nerves. — The chief artery of the tube is the tubal branch of the
uterine artery (ramus tubarius] (Fig. 1116). It also receives branches from the
ovarian (Fig. 1116). Some of the tubal veins empty into the uterine veins, some
Fimbrta uvarica.
FIG. 1120. — Uterine appendages, seen from behind. (Henle.)
into the ovarian veins. The lymphatics (Figs. 1117 and 1118) coming from the
tube unite with the trunks coming from the uterus and ovary and terminate in
the juxta-aortic glands. The nerves come from the same plexuses that send
branches to the uterus and ovary.
The Epo-ophoron, Parovarium or Organ of Rosenmiiller (Figs. 1110, 11 11, 'and
1120) is placed in the mesosalpinx, between the ovary and tube. It consists of a
number of epithelial-lined closed tubes. This structure can be readily seen if the
Fimbriated extremity
of tube.
Fallopian tube.
Broad ligament,
upper part.
Artery
vein.
Vagina, anterior wall.
FIG. 1121. — The uterus and its appendages. Posterior view. The parts have been somewhat displaced from
their proper position in the preparation of the specimen, thus the right ovary has been raised above the Fallo-
pian tube, and the fimbriated extremities of the tubes have been turned upward and outward. (From a prepa-
ration in the Museum of the Royal College of Surgeons of England.)
mesosalpinx is stretched and held in front of the light. One of these tubes runs
parallel to the Fallopian tube and is called Gartner's duct (ductus epoophori langitu-
dinalis). A number of tubes (ductuli transversi) ascend from near the ovary and
1512 THE FEMALE ORGANS OF GENERATION
each empties into Gartner's duct at a right angle. Gartner's duct is a portion of
the Wolffian duct, which has persisted and is lepresented in the male by the canal
of the epididymis. The tubules which join the duct "are derived from the meso-
nephros and represent the vasa eft'erentia and coni vasculosi of the testis, and
probably also the ductuli aberrantes of the canal of the epididymis." (Cunningham.)
The Paro-ophoron is within the mesosalpinx, but is nearer to the uterus than
is the epo-ophoron. It consists of several small tubules, which can be seen in an
adult only by the aid of a pocket lens. They are visible to the naked eye in a child
at birth. It represents the organ of Gisaldes in the male and is derived from the
mesonephros.
THE OVARY (OVARIA) (Figs. 1104, 1108, 1110, 1111, 1113, 1114, 1115,
1120, 1121).
The ovaries, the testes muliebres of Galen, are two in number and are analo-
gous to the testes in the male. They are oval-shaped bodies of an elongated
form, flattened from above downward, situated one on each side of the uterus,
in the posterior layer of the broad ligament behind and below the Fallopian tube.
Each ovary is connected by its anterior straight margin to the broad ligament;
by its lower extremity to the uterus by a proper ligament, the ligament of the
ovary (ligamentum ovarii proprium) (Fig. 1120); and by its upper end to the
fimbriated extremity of the Fallopian tube by the ovarian fimbria (fimbria ovarica)
(Fig. 1120), its mesal and lateral surfaces and posterior convex border are free
(Fig. 1121). The ovaries are of a grayish-pink color, and present either a smooth
or a puckered, uneven surface. They are each about an inch and a half in
length, three-quarters of an inch in width, and about a third of an inch thick,
and weigh from one to two drachms.
The exact position of the ovary has been the subject of considerable difference
of opinion, and writers are in conflict as to what is to be regarded as the normal
position. The fact appears to be that the ovary is differently placed in different
individuals. The two ovaries are seldom placed in absolutely identical positions.
Hasse has described the ovary as being situated with its long axis transverse, or
almost transverse, to the pelvic cavity. Schultze, on the other hand, believes that
its long axis is antero-posterior. Kolliker asserts that the truth lies between
these views, and that the ovary is placed obliquely in the pelvis, its long axis
lying parallel to the external iliac vessels, with its surface directed inward and out-
ward, and its convex free border upward. His has made some important observa-
tions on this subject, and his views are largely accepted. He teaches that the
uterus rarely lies symmetrically in the middle of the pelvic cavity, but is generally
inclined to one or other side, most frequently to the left, in the proportion of three
to two. The position of the two ovaries varies according to the inclination of the
uterus. When the uterus is inclined to the left, the ovary of this side lies with
its long axis vertical and with one side closely applied to the outer wall of the
pelvis, while the ovary of the opposite side, being dragged upon by the inclina-
tion of the uterus, lies obliquely, its outer extremity being retained in close appo-
sition to the side of the pelvis by the infundibulo-pelvic ligament. When, on
the other hand, the uterus is inclined to the right, the position of the two
ovaries is exactly reversed, the right 'being vertical and the left oblique. In
whichever position the ovary is placed, the Fallopian tube forms a loop around it,
the uterine half ascending obliquely over it, and the outer half, including the
dilated extremity, descending and bulging freely behind it. From this extremity
the fimbriae pass upward on to the ovary and closely embrace it.
Waldeyer1 states, as the result of the examination of fifty female .subjects,
1 Journal of Anatomy and Physiology, vol. xxxii.
THE DESCENT OF THE OVARY 1513
ranging from early childhood to advanced age, that the ovary "lies on the lateral
pelvic wall and vertically when the woman takes the erect posture." Its tubal
extremity is near the external iliac vein; its uterine end is directed downward,
while the Fallopian tube overlies it so as to cover it on its medial face entirely or
nearly so. Its convex margin looks downward and backward toward the pelvic
cavity and rectum, while its straight margin or hilum lies laterally on the pelvic
wall attached to the mesosalpinx. He also finds that it lies in a distinct but
shallow groove (fossa ovarii) limited above by the hypogastric artery and below
by the ureter, in such a manner that the ureter lies along the convex margin
of the ovary, and the hypogastric artery passes near the hilum or straight margin.
The ovary possesses two poles or extremities : (1 ) An outer, superior or tubal
extremity (extremitas tubaria ovarii}. (2) An inner, inferior or uterine extremity
(extremitas uterina ovarii). The ovary has two surfaces, an inner surface (fades
medialis), which is also upper; an outer surface (fades lateralis), which is also
lower. The posterior or free border (margo liber) is markedly convex. The anterior
border (margo mesovaricus) is almost straight and is narrow. The anterior border
is not free, but is joined to the posterior layer of the broad ligament by a peritoneal
fold known as the mesovarium. There is a groove in the anterior border called the
hilum (hilus ovarii), through which vessels and nerves to pass, and emerge from
the ovary.
Supports and Connections of the Ovary.
From its upper extremity a peritoneal fold is continuous with the peritoneum
over the iliac vessels and Psoas muscle. It is called the ovario-pelvic fold or the
suspensory ligament (ligamentum suspensorium ovarii) (Fig. 1104). It is in reality
a portion of the broad ligament, and within it are the ovarian vessels and nerves.
The vessels (Fig. 1121) and nerves go to the anterior border of the ovary and are
surrounded by a peritoneal sheath derived from the posterior layer of the broad
ligament; it is thus evident that the anterior border of the ovary is connected to
the posterior portion of the broad ligament by a very short mesentery, the meso-
varium1 (Fig. 1114). The ligament of the ovary or ovarian ligament (Figs. 1104
and 1120) is a round, cord-like structure, composed chiefly of non-striated muscle-
fibres, which passes between the two folds of the broad ligament from the lower
extremity of the ovary to the lateral angle of the uterus. The ovarian fimbria
(Fig. 1120), as previously stated, passes to the upper extremity of the ovary
from the extremity of the Fallopian tube.
The Descent of the Ovary.
In the female there is a gubernaculum which effects a considerable change in
the position of the ovary, though not so extensive a change as is effected upon the
male testicle. The gubernaculum in the female, as it lies on either side in con-
tact with the fundus of the uterus formed by the union of the Miillerian ducts,
contracts adhesions to this organ and thus the ovary is prevented from descending
below this level. The remains of the gubernaculum — that is to say, the part
between the attachment of the cord to the uterus to its termination in the labium
majus — ultimately forms the round ligament of the uterus. A pouch of peri-
toneum accompanies it along the inguinal canal, analogous to the funicular process
in the male; it is called the canal of Nuck. In rare cases the gubernaculum fails
to contract adhesions to the uterus, and then the ovary descends through the
inguinal canal into the labium majus, extending down the canal of Nuck.
Under these conditions, the position of the ovary resembles the position of the
testicle in the male.
The Ovary at Different Ages. — The ovary of childhood is smooth and
even. The rupture of Graafian follicles, repeated many times, causes the surface
1 Prof. Cunningham's Text-book of Anatomy.
1514
THE FEMALE ORGANS OF GENERATION
of the ovary to become pitted, puckered, fibrous, and uneven in old age. The sur-
face of the ovary is grayish-red in color. The corpus luteum of a non-pregnant
woman slowly degenerates and disappears. The corpus luteum of an impreg-
nated woman enlarges during pregnancy.
Structure (Figs. 1114, 1115, 1122, and 1123).— The ovary consists of a number
of Graafian follicles or vesicles embedded in the meshes of a stroma or framework,
and invested by a serous covering derived from the peritoneum.
Serous Covering. — Though the investing membrane of the ovary is continuous
with the peritoneum near the hilum of the ovary (the point of junction being
indicated by a narrow white" line), it differs essentially from the peritoneum,
inasmuch as it is an epithelial structure and consists of a single layer of columnar
epithelial cells, instead of the flattened endothelial cells of other parts of the
membrane; this has been termed the germinal epithelium of Waldeyer, and gives
to the surface of the ovary a dull-gray aspect instead of the shining smoothness
of serous membranes generally.
Stroma. — The stroma is a peculiar soft tissue, abundantly supplied with blood-
vessels, consisting for the most part of spindle-shaped cells, with a small amount
of ordinary connective tissue. These cells have been regarded by some anatomists
as unstriped muscle-cells, which, indeed, they most resemble (His); by others as
connective-tissue cells (Waldeyer, Henle, and Kolliker). On the surface of the
organ this tissue is much condensed, and forms a layer composed of short connec-
tive-tissue fibres, with fusiform cells between them. This was formerly regarded
as a distinct fibrous covering, and was termed the tunica albuginea, but is nothing
more than a condensed layer of the stroma of the ovary.
Graafian Follicles or Vesicles (folliculi oophori vesicidori [Graafi]) (Figs. 1122 and
1123). — Upon making a section of an ovary numerous round transparent vesicles
of various sizes are to be seen; they are the Graafian vesicles or ovisacs containing
the ova. Immediately beneath the superficial covering is a layer of stroma, in
which are a large number of minute vesicles of uniform size, about yo-j- of an
inch in diameter. These are the Graafian vesicles in their earliest condition, and
the layer where they are found has been termed the cortical layer. They are
especially numerous in the ovary of the young child. After puberty and during the
whole of the child-bearing period large and mature, or almost mature, Graafian
vesicles are also found in the cortical
layer in small numbers, and also
corpora lutea, the remains of vesicles
which have burst and are undergoing
atrophy and absorption. Beneath
this superficial stratum other large
and mature Graafian vesicles are
Ovum.
Granular zone.
Peritoneum.
FIG. 1122. — Section of the ovary. 1, outer covering:
1', attached border; 2, central stroma; 3, peripheral
stroma; 4. blood-vessels; 5, Graafian follicles in their
earliest stage; 6, 7, 8, more advanced follicles; 9, an almost
mature follicle; 9', follicle from which the ovum has
escaped; 10, corpus luteum. (After Schron.)
VJ I '[•- Coats of the
Stroma of the ovary ' » Graaflan vesicle,
u'ith, blood vessels. Membrana
granulosa.
FIG. 1 123. — Section of the Graafian vesicle.
(After von Baer.)
found embedded in the ovarian stroma. These increase in size as they recede
from the surface toward a highly vascular stroma in the centre, of the organ,
termed the medullary substance (zona vasculosa [Waldeyeri]). This stroma forms
THE DESCENT OF THE OVARY 1515
the tissue of the hilum by which the ovary is attached, and through which the
blood-vessels enter; it does not contain any Graafian vesicles.
The larger Graafian follicles consist of an external fibro- vascular coat connected
with the surrounding stroma of the ovary by a network of blood-vessels; and an
internal coat, named the ovicapsule, which is lined by a layer of nucleated cells,
called the membrana granulosa. The fluid contained in the interior of the vesicles
is transparent and albuminous, and in it is suspended the ovum. In that part of
the mature Graafian vesicle which is nearest the surface of the ovary the cells
of the membrana granulosa are collected into a mass which projects into the
cavity of the vesicle. This is termed the discus proligerus, and in this the ovum
is embedded.
The ova are formed from the germinal epithelium on the surface of the ovary.
This becomes thickened, and in it are seen some cells which are larger and more
rounded than the rest; these are termed the primordial ova. The germinal epi-
thelium grows downward in the form of tubes or columns, termed the egg tubes
of Pfliiger, into the ovarian stroma, which grows outward between the tubes, and
ultimately cuts them off from the germinal epithelium. These tubes are further
subdivided into rounded nests or groups each containing a primordial ovum which
undergoes further development and growth, while the surrounding cells of the nest
form the epithelium of the Graafian follicle.
The development and maturation of the Graafian vesicles and ova continue
uninterruptedly from puberty to the end of the fruitful period of woman's life,
while their formation commences before birth. Before puberty the ovaries are
small, the Graafian vesicles contained in them are disposed in a comparatively
thick layer in the cortical substance; here they present the appearance of a large
number of minute closed vesicles, constituting the early condition of the Graafian
vesicle; many, however, never attain full development, but shrink and disappear.
At puberty the ovaries enlarge and become more vascular, the Graafian vesicles
are developed in greater abundance, and their ova are capable of fecundation.
Discharge of the Ovum.^-The Graafian vesicles, after gradually approaching
the surface of the ovary, burst; the ovum and fluid contents of the vesicles are
liberated, and escape on the exterior of the ovary, passing thence into the Fallopian
tube. This is effected either by application of the tube to the ovary, or by a
curling upward of the fimbriated extremity, so that the ovum is caught as it falls.
In the foetus the ovaries are situated, like the testes, in the lumbar region, near
the kidneys. They may be distinguished from those bodies at an early period by
their elongated and flattened form, and by their position, which is at first oblique
and then nearly transverse. They gradually descend into the pelvis.
The Round Ligament (p. 1503).
Vessels and Nerves. — The arteries of the ovaries (Figs. 1116 and 1121) are the
ovarian from the aorta, corresponding to the spermatic arteries in the male. The
ovarian artery on each side enters the pelvis in the fold of broad ligament known
as the suspensory ligament of the ovary and enters the attached border, or hilum,
of the ovary. The ovarian vessels anastomose about the hilum with branches of
the uterine artery. The veins follow the course of the arteries; they form a plexus
near the ovarj, the pampiniform plexus, corresponding to a like structure near the
male testicle. The lymphatics (Figs. 1117 and 1118) terminate in the glands to
the corresponding side of the aorta, and they anastomose in their course with
trunks from the uterine fundus and Fallopian tube. The nerves come from the
ovarian plexus, which is a continuation of the renal plexus along the ovarian artery,
and from the aortic plexus.
Surgical Anatomy of the Appendages. — Extra-uterine pregnancy most commonly occurs
in the ampulla of the tube. The product of the conception may escape through the ostium
abdominale or the walls of the tube may rupture, a violent hemorrhage resulting.
1516 THE FEMALE ORGANS OF GENERATION
Pelvic peritonitis is a not uncommon sequence of tubal disease. Salpingitis is inflammation
of the mucous coat of the tube — interstitial salpingitis of the middle coat, perisalpingitis of the
peritoneal coat.
If inflammation closes the uterine and the abdominal ends of the tube, mucus gathers and dis-
tends the tube (hydrosalpiruc). If purulent matter gathers, the condition is known as pyosalpinx.
An ovary may fail to descend and remain well above the pelvic brim; it may prolapse into
Douglas's pouch; it may enter the sac of a hernia; it may inflame; a tumor or cyst may arise from
it. A solid tumor of the ovary may be a fibroma, a sarcoma, or a carcinoma. " Cysts may orig-
inate in any part of the tubo-ovarian structure; as the cortical, medullary, or parenchymatous
portions of the ovary; in the structure between the tube and ovary known as the Rosenmiiller
organ or parovarian structures; and in the hydatid of Morgagni."1 Cysts may be simple, pro-
liferating, or dermoid; unilocular or multilocular. Glandular proliferous cysts, papillary pro-
liferous cysts, dermoid cysts, and parovarian cysts may attain a large or even an enormous size.
The operation for the removal of an ovarian cyst is one of the most successful of the major
procedures of surgery.
THE MAMMARY GLAND (MAMMA) (Figs. 1124, 1125, 1126, 1127).
The breasts, mammary glands or mammae secrete the milk, and are accessory
glands of the generative system. They develop fully in the female, but remain
permanently rudimentary in the male. There are two of these glands, and
they are situated in the superficial fascia of the anterior portion of the thorax.
Between the two glands and in front of the sternum is a groove, the bosom.
Description of a Well-developed Breast. — Each gland appears as a hemispher-
ical body projecting from the front of the thorax beneath the skin and lying over
a portion of the Pectoralis major muscle and a smaller portion of the Serratus
magnus muscle. The hemispherical projection extends usually from the margin
of the sternum to the axilla and from the level of the second rib to the level of
the sixth rib, or from the third rib to the seventh rib, but this does not represent
the real size of the gland. The gland is much larger than this, being rendered
so by tails or prolongations of breast tissue, which will be described later (p. 1517).
The Nipple (papilla mammae) (Figs. 1124, 1125, 1126, and 1127). — The nipple
projects from a little below and to the median side of the summit of the hemi-
sphere at or above the level of the fifth rib, and is covered with thin skin. The
right nipple may not exactly correspond in situation and direction to the left
nipple. The nipple varies considerably in height and shape. In the virgin it is
usually cylindrical and is directed forward and slightly upward and outward.
The apex of the nipple is rendered rough by fissures (Fig. 1124), it exhibits a
depression in which are the openings of the milk ducts (Fig. 1126), and its cir-
cumference is thrown into concentric ridges (Fig. 1126). The nipple is surrounded
by a darker circular wrinkled area, the areola (areola mammae) (Figs. 1124 and
1125), in which are sweat-glands and on which are twelve or fifteen small
rounded elevations. These elevations are caused by cutaneous sebaceous glands
which in structure represent a transition between sebaceous and mammary glands.
They are probably rudimentary portions of the mammary gland and are known
as the glands of Montgomery (glandulae areolares) (Fig. 1126). The color of the
nipple and areola varies with the complexion of the individual. In brunettes it is
darker than in blondes. The usual color of the nipple in a young woman is rosy-
pink, the areola being of a darker shade. During the early months of pregnancy
the nipple and areola become dark brown in color, the areola becomes larger in
circumference, and the glands of Montgomery increase in size (Fig. 1127). The
nipple contains non-striated muscle and mechanical irritation or sexual excitement
makes it stiff and erect. The skin covering the breast is clear, soft, and delicate,
and subcutaneous veins are often visible. The skin of the nipple and areola is
particularly delicate.
1 Text-book of Gynecology. By E. E. Montgomery.
THE MAMMARY GLAND
1517
Variations in the Mammae. — Before puberty the glands are small, of the infantile
type, grow slowly, and differ but slightly from the male organs. The nipple is
small and flat and pale. At puberty the increase in the size of the breast is rapid
and considerable, due to growth of gland tissue and of subcutaneous fat. During
pregnancy the breasts enlarge greatly and remain very large throughout lactation.
This enlargement is due to new gland tissue and increased vascularity. Numerous
blue veins are visible in the skin, the areola darkens, and the glands of Mont-
gomery enlarge (Fig. 1127). During lactation the associated lymphatic glands may
enlarge (A. Marmaduke Sheild). After the termination of lactation the breasts
diminish in size. They do not become as small as the virgin breast, are apt to lose
their hemispherical outlines, and cease to be soft. They droop as flaccid pendulous
masses, the subcutaneous fat is largely gone, and the outlines of the lobular breast
tissue can be seen and felt. The nipple is long and hangs down like a teat. At
the menopause the breast usually shrinks. In some cases, however, it actually
increases in size. In such a case, although the gland atrophies, there is an exten-
sive deposit of fat. In old age the glands undergo atrophy and largely disappear,
the skin is flabby and thrown into wrinkles, and the breasts contain very little
glandular structure, and are hard from the presence of fibrous tissue. The nipples
become pigmented and corrugated. Women vary greatly in the development of
the breasts. In some women they are large, firm, and well proportioned; in others
they are small, flat, or atrophy occurs in the course of certain bodily diseases, as
phthisis, and certain mental diseases, as melancholia. If the ovaries are ill-
developed the breasts remain flat and small. In newly married women, even
though pregnancy does not exist, the breasts often develop decidedly and rapidly.
The outline and direction of the breast and also of the nipple may be altered by
corsets. The left mamma is usually somewhat larger than the right.
Nipple.
Areola.
Fat
Lobule unravelled
Lactiferous
duct.
Ampulla.
Lobule. "*^^^¥f ]^ *' ^^jj^^^^ Loculi in connective tissue.
FIG. 1124.— Dissection of the lower half of the female breast during the period of lactation. (From Luschka.)
One gland or both glands may be entirely absent, the nipple being also absent.
One or both glands may be absent, one or both nipples being present. When there
is only one nipple, it is apt to be the left. The term polymazia (mammae acces-
soriae muliebris) means the presence of supernumerary breasts, with or without
1518 THE FEMALE ORGANS OF GENERA TION
nipples. Polythelia means the presence of supernumerary nipples, the associated
glandular structure being rudimentary. There may be one, two, or several super-
numerary breasts, and when more than one exists, are usually asymmetrical. If
one is functionally active, it enlarges during pregnancy and furnishes milk.
Supernumerary mammae may secrete milk or may be without function. The
most common situation is on the part of the chest below and to the inner side of
the normally placed gland. They may also exist in the axilla, the abdomen, the
groin, the back, and the thigh. Many cases of supposed supernumerary glands
have been really instances in which moles, warts, or sebaceous cysts have been
mistaken for breast tissue, but some cases are undoubted.
Prolongations of Mammary Tissue. — As previously stated, the outlines of
the breast are not regular, but here and there tails, prolongations, or cusps come off
from and are true portions of the gland. Two or even more prolongations pass to
the edge of the sternum ; others pass toward the axilla, the clavicle, and the origin
of the external oblique muscle from the ribs. Underneath the mammary gland
prolongations of mammary tissue penetrate the pectoral fascia (Heidenhain) .
If one of the glandular cusps is of considerable size it is called an outlying
lobule.
Structure of Mammary Gland and Nipple (Figs. 1124 and 1 125).— The glands of
the breast (corpus mammae) rest by a smooth posterior surface upon the loose pectoral
fascia, which fastens the breast to the muscle beneath, but so loosely that the breast
is movable. The mamma consists of gland-tissue; of fibrous tissue, connecting its
lobes, of fatty tissue in the intervals between the lobes, of retinacula, and of skin.
The gland-tissue, when freed from fibrous tissue and fat, is of a pale reddish color,
firm in texture, in general circular in form, with prolongations here and there, flat-
tened from before backward, thicker in the centre than at the circumference, and
presenting several inequalities on its surface, especially in front. On the anterior
surface there are many irregular elevated processes with deep spaces between
them. From the summits of the elevations connective-tissue strands (retinacula
cutis) pass to the true skin. The glandular structure consists of numerous lobes
(lobi mammae), and these are composed of lobules (lobuli mammae), connected
together by areolar tissue, blood-vessels, and ducts. The smallest lobules con-
sist of a cluster of rounded alveoli (Fig. 1124), which open into the smallest
branches of the excretory ducts; these ducts, uniting, form larger ducts, which
terminate in single canals. Each canal is called a lactiferous, galactophorous or
mammillary duct (ductus lactiferw) (Fig. 1124). Each lobe possesses one lac-
tiferous duct. This passes to the apex of the lobe and then into the nipple.
The lactiferous ducts are white and cord-like, and contrast with the yellowish-
red tissue of the gland itself. The number of excretory ducts varies from fifteen
to twenty. They converge toward the areola, beneath which each duct forms
a spindle-shaped dilatation, the ampulla (sinus lactiferans) (Fig. 1124). The
ampullae serve as reservoirs for the milk. At the base of the nipple the ducts
become contracted and pursue a straight course to its summit, perforating it by
separate orifices considerably narrower than the ducts themselves. Each orifice
(porus lactiferus) is the orifice of a tube which drains an individual lobe. The
ducts are composed of areolar tissue, with longitudinal and transverse elastic
fibres; muscular fibres are entirely absent; their mucous lining is continuous, at
the point of the nipple, with the integument. The epithelium of the mammary
gland differs according to the state of activity of the organ. In the gland of a woman
who is not pregnant or nursing the alveoli are very small and solid, being filled
with a mass of granular polyhedral cells. During pregnancy the alveoli enlarge
and the cells undergo rapid multiplication. At the commencement of lactation
the cells in the centre of an alveolus undergo fatty degeneration, and are elim-
inated in the first milk as colostrum-corpuscles. The peripheral cells of the alveolus
remain, and form a single layer of granular, short columnar cells lining the limit-
THE MAMMARY GLAND
1519
ing membrana propria. The single nucleus of each cell divides and forms two.
In the protoplasm, especially, in the end of the cells toward the alveolus,
FIBROUS SEPTUM
GLAND SUBSTANCE
ADIPOSE TISSUE
AREOLA
NIPPLE
FIRST
RIB
SECOND
RIB
PtCTORALIS
MINOR
INTERCOSTALES
SHEATH OF PEC-
TORALIS MAJOR
THIRD RIB
AREOLAR TISSUE
SUPERFICIAL
FASCIA
FOURTH RIB
LUNG
ADIPOSE TISSUE
.HORIZONTAL PLANE
OF NIPPLE
FIFTH RIB
FIG. 1125. — Right breast in sagittal section, inner surface of outer segment. (Testut.)
drops of fat appear, and the nucleus toward this end of the cell also becomes
fattv.
SECONDARY ARtOLA
;:, CONCENTRIC
RIDGES
FIG. 1126. — Nipple and areola of a virgin. (Testut.)
FIG. 1127. — Nipple and areolae of a preg-
nant woman. (Testut.)
The end of the cell toward the alveolus breaks down, and the liberated mate-
rial constitutes " the albuminous ingredients of the milk, while the drops of fat
become the milk-globules. The portion of the cell which remains forms new
1520
THE FEMALE ORGANS OF GENERATION
cytoplasm, and the same process is repeated over and over again. The cells
also secrete water and the salts which are found in the milk."1
The fibrous tissue (Fig. 1125) invests the entire surface of the breast, and sends
down septa between its lobes, connecting them together.
The fatty tissue (Figs. 1124 and 1125) surrounds the surface of the gland and
occupies the interval between its lobes. It usually exists in considerable abun-
dance, and determines the form and size of the gland. There is no fat immediately
beneath the areola and nipple.
FIG. 1128. — The lymphatic vessels of the anterior surface of the bieast; the subareolar plexus and the
trunks which run from it. (Sappey.)
Vessels and Nerves. — The arteries supplying the mammary gland are derived
from the perforating branches of the internal mammary, long thoracic branches of the
axillary, and branches from the intercostals. The veins describe an anastomotic
circle around the base of the nipple, called by Haller the circulus venosus. From
this large branches transmit the blood to the circumference of the gland and end
in the axillary and internal mammary veins. The lymphatics of the mammary
gland (Figs. 1128 and 1129) and mammary region have been previously described
(pp. 810 and 811). The nerves are derived from the fourth, fifth, and sixth
intercostal nerves, and sympathetic filaments from the dorsal cord pass to the breast
along the branches of the intercostal nerves.
Surgical Anatomy. — Occasionally the mammary gland undergoes enormous hypertrophy.
This may occur at any age, even in the virgin. The physiological enlargement of puberty may
become excessive or the physiological enlargement of pregnancy and lactation may continue
and increase after the termination of lactation. The chief elements in the enlargement are fat
and connective tissue, and it is doubtful if there is extensive reproduction of glandular tissue.
Abscess of the breast may occur at any age, but is most common by far in nursing women.
The portals are opened to infection by a crack in the nipple and bacteria are carried inward
by the lymph- vessels. In some cases the pus gathers beneath the skin (supra-mammary abscess),
in others in the breast tissue (intra-mammary abscess). In rare cases pus gathers beneath the
breast (retro-mammary abscess). In intra-mammary abscess the pus burrows through the
1 Human Physiology. By Joseph Howard Raymond.
THE MAMMARY GLAND
1521
fibrous septa or fascia and forms numerous channels, and such a channel is constricted at the
point where it passes through fascia or a fibrous septum, as an hour-glas? is constricted.
In every patient suffering from abscess the nipple should be examined for a sore or crack, and
the area when found should be treated antiseptically. A supra-mammary abscess should be
opened by an incision radiating from the nipple.
In intra-mammary abscess follow the advice of Sheild: open the abscess by an incision radiating
from the nipple, insert the index finger, and when possible pass it to the bottom of the abscess
and carry the tip from the depths of the abscess to as near the surface as possible. At this point
make a counter opening. The finger breaks down septa which cause constriction and thus con-
verts the tracking sinuses into one large cavity.1 Drain by tubes.
A retro-mammary abscess is opened by an incision, following the outline of the breast at the
thoraco-mammary junction, the finger being pushed through the incision and up under the gland.
Tuberculosis of the breast may occur, and if it does, cold abscess is apt to form. The best
treatment is removal of the gland and the associated lymph glands.
Chronic mastitis is a condition of mammary fibrosis, most common in neurotic single women,
and apt to be associated with ovarian or uterine disease.
Meuignant dermatitis or Paget's disease of the nipple is a chronic condition consisting of
epithelial proliferation, induration, desquamation, and ulceration, and it is apt to be followed
by epithelioma.
Chancre of the nipple is occasionally met with.
Secondary and tertiary syphilitic lesions are seen upon the skin of the breast, the nipple, and
the areola.
Cysts and tumors are common in the breast.
DELTA-PECTORAL HUMCAAL CHAIN
CENTRAL-
GROUP
SCAPULAR
CHAIN
THORACIC
CHAIN
CUTANEOUS COLLECTING
TRUNK FROM THE
THORACIC WALL
MAMMARY LYMPHATIC
ENDING IN SUB-
CLAVIAN GLANDS
THORACIC
CHAIN
MAMMARY COL-
LECTING TRUNKS
8UBAREOLAR
PLEXUS
CUTANEOUS COL-
LECTING TRUNKS
I
COLLECTING TRUNKS
PASSING TO INTERNAL
MAMMARY GLANDS
MAMMAF
FIG. 1129.— Lymphatics of the breast and axillary glands. (Poirier and Charpy.)
There may be cystic degeneration of the gland in women near the menopause (involution
cysts); a lacteal cyst; a hydatid cyst; an adenoma may become cystic.
The nipple may suffer from epithelioma, myoma, myxoma, angioma, papilloma, or fibroma.
The innocent tumors of the breast are fibro-adenoma, cystic adenoma, myxoma, and angioma.
The skin of the breast majj suffer from any form of growth or cyst which could arise from
the skin of another part. Malignant tumors of the glandular structure are ten times as frequent
as innocent tumors. Sarcoma is rare; carcinoma is very common.
Carcinoma of the breast has occupied much of the attention of surgeons during recent years.
The old operation was uniformly followed by recurrence. The modern radical operation has
been evolved from the studies of Moore, the younger Gross, Heidenhain, Stiles, Banks, Halsted,
and others. The modern operation always removes at least the skin and subcutaneous tissue
over the hemispherical portion of the breast, the outlying lobules of the breast, the pectoral fascia,
1 Diseases of the Breast. By A. Marmaduke Sheild.
96
1522 THE FEMALE ORGANS OF GENERATION
and the sternal portion of the great Pectoral muscle, the lymphatic tracts from the breast, the
lymphatic glands and cellular tissue from the axilla, and from beneath the ktissimus dorsi muscle.
The pectoral fascia and the sternal portion of the great Pectoral muscle must corne away in every
case, because breast tissue may pass through the fascia. The entire breast must be removed,
because even in a recent case the entire breast is regarded as infected. The clavicular portion
of the great Pectoral muscle is anatomically distinct from the sternal portion and its removal is
not imperative. Some operators remove the lesser Pectoral muscle. To leave it is of no value to
the arm, and it frequently causes an annoying rigid band anterior to the axilla. To take it away
gives ready access to the axillary vessels at a desirable point above. The sheath of the axillary
vein should be removed with the glands and cellular tissue of the axilla. The glands receiving
lymph from the cancerous area must be removed, of course. In view of the fact that in an
undetermined percentage of cases a lymph tract passes direct to the subclavian glands, it is
evident that these glands may become infected by this route instead of, as is more usual, secondarily
to axillary infection ; hence it seems wiser in every case to remove the cellular tissue and glands
from the subclavian triangle. All of these structures should be removed as one piece, in order
to avoid cutting across lymph tracts and flooding the wound with carcinoma cells which might
adhere, grow, and reproduce cancer.
Halsted's operation is the method adopted by most surgeons. The wound cannot be com-
pletely closed, and the raw spot is covered at once or later with Thiersch skin grafts. (For sur-
gical considerations regarding the lymphatics in mammary carcinoma see page 811.)
The Male Breast (mamma virilis). — The male breast is a small flat struc-
ture, consisting chiefly of connective tissue, but containing some branched tubules.
Under normal circumstances it remains permanently of the infantile type. It
possesses a nipple which is much smaller than that of the female breast, and
which usually lies over the fourth intercostal space, but may lie over the fourth or
fifth rib. The nipples of the two sides are rarely placed quite symmetrically.
Accessory glands and accessory nipples are as common among males as females.
The male breast may exhibit some evidence of temporary functional activity at birth
and at puberty. Cases have been recorded of actual lactation by the male breast.
Surgical Anatomy. — The male breasts may undergo enormous hypertrophy (gynaecomazia).
In these cases the penis is often small and the testicles may be atrophied. The breasts may
be absent in the male. Disease of the male breast is not nearly so frequent as disease of the
female breast. The organ may be the seat of syphilis, tuberculosis, acute or chronic mastitis,
abscess or tumor. A number of cases of cancer of the male breast have been recorded.
THE SURGICAL ANATOMY OF INGUINAL
HERNIA AND' FEMORAL HEENIA.
Dissection (Fig. 287). — For dissection of the parts concerned in inguinal hernia a male
subject, free from fat, should always be selected. The body should be placed in the supine
position, the abdomen and pelvis raised by means of blocks placed beneath them, and the lower
extremities rotated outward, so as to make the parts as tense as possible. If the abdominal walls
are flaccid, the cavity of the abdomen should be inflated through an aperture made at the umbil-
icus. An incision should be made along the middle line from a little below the umbilicus to
the symphysis pubis, and continued along the front of the scrotum, and a second incision from
the anterior superior spine of the ilium to just below the umbilicus. These incisions should
divide the integument, and the triangular-shaped flap included between them should be reflected
downward and outward, when the superficial fascia will be exposed.
The Superficial Fascia of the Abdomen (p. 434). — This, over the greater part of
the abdominal wall, consists of a single layer of fascia, which contains a variable
amount of fat; but as it approaches the groin it is easily divisible into two layers,
between which are found the superficial vessels and nerves and the superficial
inguinal lymphatic glands.
The Superficial Layer of the Superficial Fascia or the Fascia of Camper is thick,
areolar in texture, containing adipose tissue in its meshes, the quantity of which
varies in different subjects. Below, it passes over Poupart's ligament, and is con-
tinuous with the outer layer of the superficial fascia of the thigh. In the male this
fascia is continued over the penis and over the outer surface of the cord to the
scrotum, where it helps to form the dartos. As it passes to the penis, and over the
cord to the scrotum it changes its character, becoming thin, destitute of adipose
tissue, and of a pale reddish color; and in the scrotum it acquires some involuntary
muscular fibres. From the scrotum it may be traced backward, to be continuous
with the superficial fascia of the perinseum. In the female this fascia is continued
into the labia majora.
The hypogastric branch of the ilio -hypo gastric nerve perforates the aponeurosis
of the External oblique muscle about an inch above and a little to the outer side of
the external abdominal ring, and is distributed to the integument of the hypogas-
tric region.
The ilio-inguinal nerve escapes at the external abdominal ring, and is distributed
to the integument of the upper and inner part of the thigh, to the scrotum in the
male and to the labium in the female.
The superficial epigastric artery arises from the femoral about half an inch
below Poupart's ligament, and, passing through the saphenous opening in the fascia
lata, ascends on to the abdomen, in the superficial fascia covering the External
oblique muscle, nearly as high as the umbilicus. It distributes branches to the
superficial inguinal lymphatic glands, the superficial fascia, and the integument,
anastomosing with branches of the deep epigastric and internal mammary
arteries.
The superficial circumflex iliac artery, the smallest of the cutaneous branches,
arises close to the preceding, and, piercing the fascia lata, runs outward, parallel
with Poupart's ligament, as far as the crest of the ilium, dividing into branches
which supply the superficial inguinal lymphatic glands, the superficial fascia, and
( 1523 )
1524
THE SURGICAL ANATOMY OF HERNIA
the integument, anastomosing with the deep circumflex iliac and with the gluteal
and external circumflex arteries.
POUPARTS INTERCOLUMNAR
LIGAMENT FIBRES
GIMBERNAT'S
LIGAMENT
SAPHENOUS
OPENING
LONG
SAPHENOUS
VEIN
EXTERNAL
ABDOMINAL
RING
FIG. 1130. — Right external abdominal ring and saphenous opening in the male. (Spalteholz.)
EXTERNAL OBLIQUE
(reflected downward)
EXTERNAL OBLIQU
(reflected inward)
POSTERIOR WALL OF
INGUINAL CANAL
INTERNAL ORIGIN
OF CRENASTER
FIG. 1131. — Right inguinal canal in the male. Second layer viewed from in front. (Spalteholz.)
APONEUROSIS OF THE EXTERNAL OBLIQUE MUSCLE 1525
The superficial external pudic (superior) artery arises from the inner side of
the femoral artery close to the preceding vessels, and, after passing through the
saphenous opening, courses inward across the spermatic cord, to be distributed to
the integument on the lower part of the abdomen, the penis and scrotum in the male,
and the labium in the female, anastomosing with branches of the internal pudic.
The Superficial Veins. — The veins accompanying these superficial vessels are
usually much larger than the arteries; they terminate in the internal saphenous vein.
The superficial inguinal lymphatic glands are placed immediately beneath the
.integument, are of large size, and vary from ten to twenty in number (p. 791).
INTERNAL OBLIQUE
(reflected inward)
INTERNAL
OBLIQUE
EXTERNAL OBLIQUE
reflected inward)
POSTERIOR
WALL
TRIANGULAR
FASCIA
FIG. 1132. — The right inguinal canal in the male. Third layer viewed from in front. (Spalteholz.)
The Deep Layer of the Superficial Fascia, the Fascia of Scarpa or the Fascia of Cooper
p. 435) is thinner and more membranous in character than the superficial layer.
In the middle line it is intimately adherent to the linea alba; above, it is continuous
with the superficial fascia over the rest of the trunk; below, it blends with the fascia
lata of the thigh a little below Poupart's ligament ; below and internally, in the male,
it is continued over the penis and over the outer surface of the cord to the scrotum,
where it helps to form the dartos. From the scrotum it may be traced backward
to be continuous with the base of the triangular ligament of the urethra. In the
female it is continuous with the labia majora.
The scrotum is a cutaneous pouch which contains the testes and part of the
spermatic cords, and into which an inguinal hernia frequently descends.
The Aponeurosis of the External Oblique Muscle (Fig. 1130). — This is a thin
but strong membranous aponeurosis, the fibres of which- are directed obliquely
downward and inward. That portion of the aponeurosis which extends between
1526 THE SURGICAL ANATOMY OF HERNIA
the anterior superior spine of the ilium and the spine of the os pubis is a broad
band, folded inward and continuous below with the fascia lata; it is called Poupart's
ligament (Figs. 288, 1130, 1133, 1134, 1135, 1141, and 1142). The portion which is
reflected from Poupart's ligament at the spine of the os pubis, along the pectineal
line, is called Gimbernat's ligament (Fig. 296, 338, 1130, 1141, and 1142). A thin
fibrous band extends from the inner end of Poupart's ligament and Gimbernat's
ligament upward and inward behind the inner pillar of the external ring to the
anterior layer of the rectus sheath. The fibres diverge as they ascend. This
band is known as the triangular fascia or Colles's fascia or the triangular ligament
of Colles (Figs. 1132 and 1136).
The External or Superficial Abdominal Ring (annulus inguinalis subcutaneus)
(Figs. 288 and 1130). — Just above and to the outer side of the crest of the os pubis
an interval is seen in the aponeurosis of the External oblique, called the external
abdominal ring. This aperture is oblique in direction, somewhat triangular in
form, and corresponds with the course of the fibres of the aponeurosis. It usually
measures from base to apex about an inch, and transversely about half an inch.
It is bounded below by the crest of the os pubis; above, by a series of curved
fibres, the intercolumnar fibres, which pass across the upper angle of the ring, so as
to increase its strength; and on either side by the margins of the opening in the
aponeurosis, which are called the columns or pillars of the ring.
The External Pillar, which at the same time is inferior (crus inferius), from the
obliquity of its direction, is the stronger; it is formed by that portion of Poupart's
ligament wrhich is inserted into the spine of the os pubis ; it is curved, so as to form
a kind of groove, upon which the spermatic cord rests.
The Internal or Superior Pillar (crus superius) is a broad, thin, flat band, which
is attached to the front of the body of the os pubis, interlacing with its fellow of
the opposite side in front of the symphysis pubis, that of the right side being
superficial.
The external abdominal ring gives passage to the spermatic cord in the male
and round ligament in the female; it is much larger in men than in women, on
account of the large size of the spermatic cord, hence the great frequency of inguinal
hernia in men.
The Intercolumnar Fibres (fibrae intercrurales) (Fig. 1130) are a series of curved
tendinous fibres which arch across the lower part of the aponeurosis of the Exter-
nal oblique. They have received their name from stretching across between the
two pillars of the external ring; they increase the strength of the lower part of the
aponeurosis and prevent the divergence of the pillars from one another. They
are thickest below, where they arise from Poupart's ligament, and they are
inserted into the linea alba, describing a curve, with the convexity downward.
They are much thicker and stronger at -the outer angle of the external ring than
internally, and are more strongly developed in the male than in the female.
These intercolumnar fibres, as they, pass across the external abdominal ring, are
themselves connected together by delicate fibrous tissue, thus forming a fascia
which, as it is attached to the pillars of the ring, covers it in, and is called the
intercolumnar fascia. This intercolumnar fascia is continued downward as a
tubular prolongation around the outer surface of the cord and testis, and encloses
them in a distinct sheath; hence, it is also called the external spermatic fascia.
The sac of an inguinal hernia in passing through the external abdominal ring
receives an investment from the intercolumnar fascia.
If the finger is introduced a short distance into the external ring and the limb
is then extended and rotated outward, the aponeurosis of the External oblique,
together with the iliac portion of the fascia lata, will be felt to become tense and
the external ring much contracted; if the limb is, on the contrary, flexed upon the
pelvis and rotated inward, this aponeurosis will become lax, and the external ring
THE TRIANGULAR FASCIA OF THE ABDOMEN
1527
sufficiently enlarged to admit the finger with comparative ease; hence the patient
should always be put in the latter position when the taxis is applied for the reduc-
tion of an inguinal hernia, in order that the abdominal walls may be relaxed as
much as possible.
The aponeurosis of the External oblique should be removed by dividing it across in the same
direction as the external incisions, and reflecting it downward and outward; great care is requisite
in separating it from the aponeurosis of the muscle beneath. The lower part of the Internal
oblique and the Cremaster are then exposed, together with the inguinal canal, which contains
the spermatic cord (Fig. 1133). The mode of insertion of Poupart's and Gimbernat's ligaments
into the os pubis should also be examined.
Poupart's Ligament (ligamentum inguinale [Pouparti]) (Figs. 288, 1130, 1133,
1 134, 1 135, 1141 , and 1 142) or the crural arch is the lower border of the aponeurosis
of the External oblique muscle, which extends from the anterior superior spine of
the ilium to the spine of the os pubis. From this latter point it is reflected out-
ward to be attached to the pectineal line for about half an inch, forming Gimber-
nat's ligament. Its general direction is
curved downward toward the thigh,
where it is continuous with the fascia
lata. Its outer half is rounded and
oblique in direction ; its inner half grad-
ually widens at its attachment to the os
pubis, is more horizontal in direction,
and lies beneath the spermatic cord.
Gimbernat's Ligament (ligamentum
lacunare [Gimbernati]) (Figs. 288, 296,
338, 1130, 1141, and 1142) is that por-
tion of the aponeurosis of the External
oblique muscle which is reflected up-
ward and outward from the spine of
the os pubis to be inserted into the
pectineal line. It is about half an
inch in length, larger in the male than
in the female, almost horizontal in
direction in the erect posture, and of a
triangular form, with the base directed
outward. Its base or outer margin is
concave, thin, and sharp, and lies in
contact with the femoral sheath, form-
ing the inner boundary of the femoral
ring (Fig. 1141). Its apex corresponds
to the spine of the os pubis. Its pos-
tprinr maro-in i<? nttarVipd to rhp npr- FIG. 1133.— Inguinal hernia. Dissection showing the
margin Internal oblique and Cremaster.
tineal line, and is continuous with the
pubic portion of the fascia lata. Its anterior margin is continuous with Poupart's
ligament.
The Triangular Fascia of the Abdomen, Colles's Fascia or the Triangular Ligament
of Colles (ligamentum inguinale reflexum [Collesi]) (Figs. 1132, 1133, and 1136) is a
band of tendinous fibres, of a triangular shape, which is attached by its apex to
the inner end of Poupart's ligament and to Gimbernat's ligament. It passes
inward beneath the spermatic cord, and expands into a somewhat fan-shaped
fascia, lying behind the inner pillar of the external abdominal ring and in front
of the conjoined tendon, and interlaces with the ligament of the other side at the
linea alba in the anterior layer of the sheath of the Rectus muscle.
1528 THE SURGICAL ANATOMY OF HERNIA
The Ligament of Cooper. — See Fig. 296 and p. 439.
The Internal Oblique Muscle (Figs. 1131, 1132, and 1133) has been previously
described (p. 439). The part which is now exposed is partly muscular and partly
tendinous in structure. Those fibres which arise from Poupart's ligament, few in
number and paler in color than the rest, arch downward and inward across the
spermatic cord, and, becoming tendinous, are inserted, conjointly with those of
the Transversalis, into the crest of the os pubis and pectineal line, forming what
is known as the conjoined tendon of the Internal oblique and Transversalis (Figs.
1133 and 1134). This tendon is inserted immediately behind the inguinal .canal
and external abdominal ring, serving to protect what would otherwise be a weak
point in the abdominal wall. The conjoined tendon is sometimes divided into
an outer and an inner portion, the former being called the ligament of Hessel-
bach (ligamentum interfoveolare) (Fig. 291), and the latter the ligament of Henle
(Fig. 291). Sometimes the conjoined tendon is insufficient to resist the pressure
from within, and is carried forward in front of the protrusion through the exter-
nal ring, forming one of the coverings of direct inguinal hernia, or the hernia
forces its way through the fibres of the conjoined tendon.
The Cremaster (Figs. 1131 and 1133) is derived from the lower margin of the
Internal oblique, of which muscle it is in reality a portion. It is a thin muscular
layer composed of a number of fasciculi. It arises by a thick external bundle of
fibres from the upper portion of Poupart's ligament, being connected with the
Internal oblique muscle and also occasionally with the Transversalis. It arises
also by a thin inner bundle of fibres from the anterior layer of the rectus
sheath.
The thick bundle of origin is on the lateral surface ; the thin bundle is on the
medial surface of the spermatic cord. The Cremaster passes along with the
spermatic cord, and descends with it through the external ring. Upon the front and
sides of the cord both bundles spread out upon the vaginal tunic of the testicle
and epididymis, and form a series of loops which differ in thickness and length
in different subjects. These loops are united together by areolar tissue, and
form a thin covering over the cord and testis, the cremasteric fascia (fascia
cremaster ica} .
It will be observed that the Cremaster is a separated portion of the Internal
oblique. This fact affords an easy explanation of the manner in which the testicle
and cord are invested by this muscle. At an early period of foetal life the testis is
placed at the lower and back part of the abdominal cavity, but during its descent
toward the scrotum, which takes place before birth, it passes beneath the arched
border of the Internal oblique. In its passage beneath this muscle some fibres
are derived from its lower part, which accompany the testicle and cord into the
scrotum.
It occasionally happens that the loops of the Cremaster surround the cord, some
lying behind as well as in front. It is probable that under these circumstances
the testis in its descent passes through, instead of beneath, the fibres of the Internal
oblique.
In the descent of an oblique inguinal hernia, which takes the same course as
the spermatic cord, the Cremaster muscle forms one of its coverings. This muscle
becomes largely developed in cases of hydrocele and large old scrotal herniae. No
such muscle exists in the female, but an analogous structure is developed in those
cases where an oblique inguinal hernia descends beneath the margin of the Internal
oblique.
The Internal oblique should be detached from Poupart's ligament, separated from the Trans-
versalis to the same extent as in the previous incisions, and reflected inward on to the sheath
of the Rectus (Fig. 11 34). The deep circumflex iliac vessels, which lie between these two muscles,
form a valuable guide to their separation.
THE INGUINAL OR SPERMATIC CANAL
1529
The Transversalis Muscle (Figs. 1132 and 1134) has been previously described
(p. 444). The part which is now exposed is partly muscular and partly tendinous
in structure; it arises from the outer third of Poupart's ligament, its fibres curve
downward and inward, and are inserted, together with those of the Internal
oblique, into the lower part of the linea alba, into the crest of the os pubis and
the pectineal line, forming what is known as the conjoined tendon of the Internal
oblique and Transversalis (Figs. 1133 and 1134). The falx aponeurotica [inguinalis]
is a collection of fibres of tendinous consistence in the inner side of the Trans-
versalis insertion. Between the lower border of this muscle and Poupart's
ligament a space is left in which is seen the transversalis fascia.
The Inguinal or Spermatic Canal (canalis inguinalis) (Figs. 1131, 1132, and 1134)
contains the spermatic cord in the male and the round ligament in the female. It
is an oblique canal, about an inch and a half in length, directed downward and
inward and placed parallel with, and a little above, Poupart's ligament. It com-
mences above at the internal or deep abdominal ring, which is the point where
Internal .
abdominal ring.
Epigastric artery.
FIG. 1134. — Inguinal hernia.
Dissection showing the Transversalis muscle, the transversalis fascia,
and the internal abdominal ring.
the cord enters the inguinal canal, and terminates below at the external or super-
ficial ring. It is bounded, in front, by the integument and superficial fascia, by
the aponeurosis of the External oblique throughout its whole length, and by the
Internal oblique for its outer third; behind, by the triangular fascia, the conjoined
tendon of the Internal oblique and Transversalis, transversalis fascia, and the
subperitoneal fat and peritoneum; above, by the arched fibres of the Internal
oblique and Transversalis; below, by the union of the transversalis fascia with
Poupart's ligament. That form of hernia in which the intestine follows the course
of the spermatic cord along the inguinal canal is called oblique inguinal hernia.
On the posterior wall of the inguinal canal is seen the band of fibres known as
the ligament of Hesselbach (ligamentum interfoveolare [Hesselbachi]) (Fig. 291).
It is placed in front of the deep epigastric artery. The fibres come from the
external portion of the lower fibres of the conjoined tendon (Fig. 1133) and pass
1530 THE SURGICAL ANATOMY OF HERNIA
downward for a distance, some of them then passing outward and upward, some
of them downward and inward to the inner surface of Poupart's ligament.
The Transversalis Fascia (Figs. 296, 1134, and 1142) is a thin aponeurotic mem-
brane which lies between the inner surface of the Transversalis muscle and the
peritoneum. It forms part of the general layer of fascia which lines the interior
of the abdominal and pelvic cavities, and is directly continuous with the iliac
and pelvic fasciae.
In the inguinal region the transversalis fascia is thick and dense in structure,
and joined by fibres from the aponeurosis of the Transversalis muscle; but it
becomes thin and cellular as it ascends to the Diaphragm. Below, it has the
following attachments; external to the femoral vessels it is connected to the
posterior margin of Poupart's ligament, and is there continuous with the iliac
fascia. Internal to the vessels it is thin, and attached to the os pubis and pectineal
line behind the conjoined tendon, with which it is united; and, corresponding to
the points where the femoral vessels pass into the thigh, this fascia descends in
front of them, forming the anterior wall of the femoral sheath. The spermatic cord
in the male and the round ligament in the female pass through this fascia; the
point where they pass through is called the internal or deep abdominal ring. This
opening is not visible externally, owing to a prolongation of the transversalis fascia
on the structures forming the infundibuliform fascia.
The Internal or Deep Abdominal Ring (annulus inguinalis abdominalis) (Figs. 296
and 1134) is situated in the transversalis fascia, midwyay between the anterior superior
spine of the ilium and symphysis pubis, and about half an inch above Poupart's
ligament. It is of an oval form, its long diameter being directed upward and
downward; it varies in size in different subjects, and is much larger in the male
than in the female. It is bounded above and externally by the arched fibres of
the Transversalis muscle, below and internally by the deep epigastric vessels. It
transmits the spermatic cord in the male and the round ligament in the female.
From its circumference, a thin, funnel-shaped membrane, the infundibuliform fascia,
is continued around the cord and testis, enclosing them in a distinct pouch (Fig.
1134). When the sac of an oblique inguinal hernia passes through the internal or
deep abdominal ring, the infundibuliform fascia constitutes one of its coverings.
The Subperitoneal Areolar Tissue or the Fascia Propria of Cooper. — Between the
transversalis fascia and the peritoneum is a quantity of loose areolar tissue. In
some subjects it is of considerable thickness and loaded with adipose tissue.
Opposite the internal ring it is continued around the surface of the cord, forming
a loose sheath for it.
The Deep Epigastic Artery (Figs. 291 and 1135) arises from the external iliac
artery a few lines above Poupart's ligament. It at first descends to reach this liga-
ment, and then ascends obliquely along the inner margin of the internal or deep
abdominal ring, lying between the transversalis fascia and the peritoneum, and
passing upward pierces the transversalis fascia and enters the sheath of the Rectus
muscle by passing over the semilunar fold of Douglas. Consequently the deep
epigastric artery bears a very important relation to the internal abdominal ring
as it passes obliquely upward and inward from its origin from the external iliac.
In this part of its course it lies along the lower and inner margin of the internal
ring and beneath the commencement of the spermatic cord. At its commence-
ment it is crossed by the vas deferens in the male and by the round ligament in
the female.
The Peritoneum (Fig. 1135), corresponding to the inner surface of the internal
ring, presents a well-marked depression, the depth of which varies in different
subjects. A thin fibrous band is continued from it along the front of the cord
for a variable distance, and becomes ultimately lost, the ligament of Cloquet.
This is the remains of the pouch of peritoneum which, in the foetus, precedes
THE PERITONEUM
1531
the cord and testis into the scrotum, the obliteration of which commences soon
after birth. In some cases the fibrous band can only be traced a short distance,
but occasionally it may be followed, as a fine cord, as far as the upper end of the
tunica vaginalis. Sometimes the tube of peritoneum is closed only at intervals
and presents a sacculated appearance, or a single pouch may extend along the
whole length of the cord, which may be closed above, or the pouch may be directly
continuous with the peritoneum by an opening at its upper part.
In the female fo?tus the peritoneum is also prolonged in the form of a tubular
process for a short distance into the inguinal canal. This process is called the
canal of Nuck. It is generally obliterated in the adult, but sometimes it remains
pervious even in advanced life.
If. iliacus.
External
inguinal
fossa.
External
iliac
artery.
External
iliac
vein.
Femoral
Internal inguinal
fossa.
Superior vesical
artery,
'iddle inguinal
fossa.
FIG. 1135. — Posterior view of the anterior abdominal wall in its lower hah. The peritoneum is in place,
and the various cords are shining through. (After Joessel.)
In order to understand the relation of the peritoneum to inguinal hernia, it is
necessary to view the anterior abdominal wall from its internal aspect, when it will
be seen as shown in Fig. 1135. Between the upper margin of the front of the
pelvis and the umbilicus, the peritoneum, when viewed from behind, will be seen
to be raised into five vertical folds, with intervening depressions, by more or less
prominent bands which converge to the umbilicus. One of these is situated in the
median line, and is caused by the urachus, the remnant of the allantois; it extends
from the summit of the bladder to the umbilicus. The fold of peritoneum covering
it is known as the fold of the urachus or the plica urachi (plica umbilwalis media).
On either side of this is a prominent band, caused by the obliterated hypogastric
artery, which extends from the side of the bladder obliquely upward and inward
to the umbilicus. This is covered by a fold of peritoneum which is known a« the
1532 THE SURGICAL ANATOMY OF HERNIA
hypogastric fold or the plica hypogastrica (plica umbilicalis lateralis). To either
side of these three cords is the deep epigastric artery, which ascends obliquely
upward and inward from a point midway between the symphysis pubis and the
anterior superior spine of the ilium to the semilunar fold of Douglas, in front of
which it disappears. It is covered by a fold of peritoneum which is known as the
plica epigastrica. Between these raised folds are depressions of the peritoneum,
constituting so-called fossae. The most internal, between the plica urachi and the
plica hypogastrica, is known as the internal inguinal fossa (fovea supravesicalis).
The middle one is situated between the plica hypogastrica and the plica epigas-
trica, and is termed the middle inguinal fossa (fovea inguinalis mesialis). The
external one is external to the plica epigastrica, and is known as the external
inguinal fossa (fovea inguinalis lateralis). Occasionally the deep epigastric artery
corresponds in position to the obliterated hypogastric artery, and then there is but
one fold on each side of the middle line, and the two external fossae are merged
into one. In the usual condition of the parts the floor of the external inguinal
fossa corresponds to the internal abdominal ring, and into this fossa an oblique
inguinal hernia descends. To the inner side of the plica epigastrica are the
two internal fossae, and through either of these a direct hernia may descend, as
will be explained in the sequel (p. 1535). The whole of this space, that is to
say, the space between the deep epigastric artery, the margin of the Rectus and
Poupart's ligament, is commonly known as Hesselbach's triangle. These three
depressions or fossae are situated above the level of Poupart's ligament, and in
addition to them is another below the ligament, corresponding to the position of
the femoral ring, and into which a femoral hernia descends.
INGUINAL HERNIA.
Inguinal hernia is that form of protrusion which makes its way through the
abdomen in the inguinal region.
There are two principal varieties of inguinal hernia — external or oblique, and
internal or direct.
External or oblique inguinal hernia, the more frequent of the two, takes the
same course as the spermatic cord. It is called external from the neck of the sac
being on the outer or iliac side of the deep epigastric artery.
Internal or direct inguinal hernia does not follow the same course as the cord,
but protrudes through the abdominal wall on the inner or pubic side of the deep
epigastric artery.
Oblique Inguinal Hernia.
In oblique inguinal hernia (Fig. 1135) the intestine or omentum escapes from the
abdominal cavity at the internal ring. Before it is a pouch of peritoneum, which
forms the hernial sac (Fig. 1137, /I). This pouch of peritoneum is invested by the
subserous areolar tissue, and is enclosed in the infundibuliform process of the trans-
versalis fascia, which it receives as it enters the inguinal canal. In passing along the
inguinal canal the hernia displaces upward the arched fibres of the Transversalis and
Internal oblique muscles, and is imperfectly surrounded by the fibres of the Cre-
master muscles, the coat being completed by the cremasteric fascia. It then passes
along the front of the cord, and escapes from the inguinal canal at the external
ring, receiving an investment from the intercolumnar fascia. Lastly, it descends
into the scrotum, receiving coverings from the superficial fascia and the integument.
The coverings of this form of hernia, after it has passed through the external
ring? are, from without inward, the integument, superficial fascia, intercolumnar
OBLIQUE INGUINAL HERNIA
1533
fascia, Cremaster muscle and fascia, infundibuliform fascia, subserous areolar
tissue, and peritoneum.
This form of hernia lies in front of the vessels of the spermatic cord and seldom
extends below the testis, on account of the intimate adhesion of the coverings
of the cord to the tunica vaginalis (Fig. 1137, A}.
The seat of stricture in a strangulated oblique inguinal hernia is either at the
external ring, in the inguinal canal, caused by the fibres of the Internal oblique
or Transversalis; or at the internal ring, most frequently in the latter situation.
If it is situated at the external ring, the division of a few fibres at one point of
its circumference is all that is necessary for the replacement of the hernia. If
in the inguinal canal or at the internal ring, it may be necessary to divide the
Flo. 1136. — Oblique inguinal hernia, showing its various coverings. (From a preparation in the
Museum of the Royal College of Surgeons.)
In
aponeurosis of the External oblique so as to lay open the inguinal canal,
dividing the stricture the direction of the incision should be upward.
When the hernia passes along the inguinal canal and escapes from the external
ring into the scrotum, the condition is called complete oblique inguinal or scrotal
hernia (Fig. 1137, A). If the hernia does not escape from the external ring, but is
retained in the inguinal canal, the condition is called incomplete inguinal hernia or
bubonocele. In each of these cases the coverings which invest the intestine or
omentum will depend upon the extent to which it descends in the inguinal canal.
There are some other varieties of oblique inguinal hernia depending upon con-
genital defects in the processus vaginalis. The testicle in its descent from the
abdomen into the scrotum is preceded by a pouch of peritoneum, which about
1534
THE SURGICAL ANATOMY OF HERNIA
the period of birth becomes shut off from the general peritoneal cavity by a closure
of that portion of the pouch which extends from the internal abdominal ring to
Sac of hernia.
Tunica
vaginalis.'''
A. Common scrotal hernia.
Tunica
-- -vaginalis.
B. Congenital hernia.
Sac of ^^
hernia.
Sac of hernia.
Tunica
'vaginalis.
Tunica vaginalis.-]- «*?
— 1 — Sac of hernia.
E Hernia into the funicular process.
FIG. 1137. — Varieties of oblique inguinal hernia
near the upper part of the testicle, the lower portion of the pouch remaining per-
sistent as the tunica vaginalis. It would appear that this closure commences at
DIRECT INGUINAL HERNIA 1535
two points — viz., at the internal abdominal ring and at the top of the epididymis
— and gradually extends until, in the normal condition, the whole of the inter-
vening portion is converted into a fibrous cord. From failure in the completion
of this process variations in the relation of the hernial protrusion to the testicle
and tunica vaginalis are produced, which constitute distinct varieties of inguinal
hernia, and which have received separate names and are of surgical importance.
These are congenital, infantile, encysted, and hernia of the funicular process.
Congenital Hernia (Fig. 1137, B). — Where the congenital pouch of peritoneum
which precedes the cord and testis in its descent remains patent throughout and
is unclosed at any point, the cavity of the tunica vaginalis communicates directly
with the cavity of the peritoneum. The intestine descends along this pouch into
the cavity of the tunica vaginalis, which constitutes the sac of the hernia, and the
gut lies in contact with the testicle.
Infantile and Encysted Hernia. — Where the congenital pouch of peritoneum
is occluded at the internal ring only, but remains patent throughout the rest of
its extent, two varieties of oblique inguinal hernia may be produced, which have
received the names of infantile and encysted hernia. In the infantile form (Fig.
1137, C) the septum which closed the congenital sac above and the peritoneum
in its immediate neighborhood yields and forms a sac, which descends behind the
tunica vaginalis, so that in front of the bowel there are three layers of perito-
neum, the two layers of the tunica vaginalis and the layer of the proper hernial
sac. In the encysted form (Fig. 1137, D) yielding occurs in the same position as
in the infantile form — namely, at the occluded spot in the pouch — and a sac forms
which projects into and not behind the tunica vaginalis, as in the infantile form,
and thus it constitutes a sac within a sac, so that in front of the bowel there are two
layers of peritoneum — one layer of the tunica vaginalis and one of true hernial sac.
Hernia into the Funicular Process (Fig. 1137, E). — Where the congenital
pouch of peritoneum is occluded at the lower point only — that is, just above the
testicle — the intestine descends into the pouch of peritoneum as far as the testicle,
but is prevented from entering the sac of the tunica vaginalis by the septum which
has formed between it and the pouch, so that it resembles the congenital form in
all respects, except that, instead of enveloping the testicle, that body can be felt
below the rupture.
Direct Inguinal Hernia.
In direct inguinal hernia the protrusion makes its way through some part of
the abdominal wall internal to the epigastric artery.
At the lower part of the abdominal wall is a triangular space, Hesselbach's
triangle, bounded externally by the deep epigastric artery, internally by the
margin of the Rectus muscle, below by Poupart's ligament (Fig. 1135). The con-
joined tendon is stretched across the inner two-thirds of this space, the remaining
portion of the space having only the subperitoneal areolar tissue and the trans-
versalis fascia between the peritoneum and the aponeurosis of the External oblique
muscle.
In some cases the hernial protrusion escapes from the abdomen on the outer
side of the conjoined tendon, pushing before it the peritoneum, the subserous
areolar tissue, and the transversalis fascia. It then enters the inguinal canal,
passing along nearly its whole length, and finally emerges from the external ring,
receiving an investment from the intercolumnar fascia. The coverings of this
form of hernia are precisely similar to those investing the oblique form, with the
insignificant difference that the infundibuliform fascia is replaced by a portion
derived from the general layer of the transversalis fascia.
In other cases — and this is the more frequent variety — the hernia is either forced
through the fibres of the conjoined tendon or the tendon is gradually distended in
1536 THE SURGICAL ANATOMY OF HERNIA
front of it so as to form a complete investment for it. The intestine then enters
the lower end of the inguinal canal, escapes at the external ring lying on the
inner side of the cord, and receives additional coverings from the superficial fascia
and the integument. This form of hernia has the same coverings as the oblique
variety, excepting that the conjoined tendon is substituted for the Cremaster, and
the infundibuliform fascia is replaced by a portion derived from the general layer
of the transversalis fascia.
The difference between the position of the neck of the sac in these two forms
of direct inguinal hernia has been referred, with some probability, to a difference
in the relative positions of the obliterated hypogastric artery and the deep epi-
gastric artery. When the course of the obliterated hypogastric artery corre-
sponds pretty nearly with that of the deep epigastric the projection of these
arteries toward the cavity of the abdomen produces two fossae in the peritoneum.
The bottom of the external fossa of the peritoneum corresponds to the position of
the internal abdominal ring, and a hernia which distends and pushes out the peri-
toneum lining this fossa is an oblique hernia. When, on the other hand, the
obliterated hypogastric artery lies considerably to the inner side of the deep epi-
gastric artery, corresponding to the outer margin of the conjoined tendon, it divides
the triangle of Hesselbach into two parts, so that three depressions will be seen on
the inner surface of the lower part of the abdominal wall — viz., an external one on
the outer side of the deep epigastric artery; a middle one, between the deep epi-
gastric and the obliterated hypogastric arteries; and an internal one, on the inner
side of the obliterated hypogastric artery (pp. 1531 and 1532). In such a case
a hernia may distend and push out the peritoneum forming the bottom of either
fossa. These fossae are the inguinal fossae. When the hernia distends and
pushes out the peritoneum forming the bottom of the external fossa, it is an
oblique or external inguinal hernia.
When the hernia distends and pushes out the peritoneum forming the bottom
of either the middle or the internal fossa, it is a direct or internal hernia.
The anatomical difference between these two forms of direct or internal inguinal
hernia is that, when the hernia protrudes through the middle fossa — that is,
the fossa between the deep epigastric and the obliterated hypogastric arteries —
it will enter the upper part of the inguinal canal ; consequently its coverings will be
the same as those of an oblique hernia, with the insignificant difference that the
infundibuliform fascia is replaced by a portion derived from the general layer of
the transversalis fascia, whereas when the hernia protrudes through the internal
fossa it is either forced through the fibres of the conjoined tendon or the tendon is
gradually distended in front of it so as to form a complete investment for it. The
intestine then enters the lower part of the inguinal canal, and escapes from the
external abdominal ring lying on the inner side of the cord.
This form of hernia has the same coverings as the oblique variety, excepting
that the conjoined tendon is substituted for the Cremaster, and the infundibuli-
form fascia is replaced by a portion derived from the general layer of the fascia
transversalis.
The seat of stricture in strangulation in both varieties of direct hernia is most
frequently at the neck of the sac or at the external ring. In that form of hernia
which perforates the conjoined tendon it not unfrequently occurs at the edges of
the fissure through which the gut passes. In dividing the stricture the incision
should in all cases be directed upward.1
If the hernial protrusion passes into the inguinal canal, but does not escape
1 In all cases of inguinal hernia, whether oblique or direct, it is proper to divide the stricture directly upward:
the reason of this is obvious, for by cutting in this direction the incision is made parallel to the deep epigastric
artery — either external to it in the oblique variety, or internal to it in the direct form of hernia — and thus all
chance of wounding the vessel is avoided. If the incision was made outward, the artery might be divided if the
hernia was direct; and if made inward, the vessel would stand an equal chance of injury ifthe case was one of
oblique inguinal hernia. — ED. of 15th English edition.
FEMORAL HERNIA 1537
from the external abdominal ring, it forms what is called incomplete direct hernia.
This form of hernia is usually of small size, and in corpulent persons is very
difficult of detection.
Direct inguinal hernia is of much less frequent occurrence than the oblique,
their comparative frequency being, according to Cloquet, as one to five. It occurs
far more frequently in men than in women, on account of the larger size of the
external ring in the former sex. It differs from the oblique in its smaller size and
globular form, dependent most probably on the resistance offered to its progress
by the transversalis fascia and conjoined tendon. It differs also in its position,
being placed over the os pubis and not in the course of the inguinal canal. The
deep epigastric artery runs on the outer or iliac side of the neck of the sac, and the
spermatic cord along its external and posterior side, not directly behind it, as in
oblique inguinal hernia.
FEMORAL HERNIA.
The dissection of the parts comprised in the anatomy of femoral hernia should be performed,
if possible, upon a female subject free from fat. The subject should lie upon the back; a block
is first placed under the pelvis, the thigh everted, and the knees slightly bent and retained in
this position. An incision should then be made from the anterior superior spinous process of
the ilium along Poupart's ligament to the symphysis pubis; a second incision should be carried
transversely across the thigh about six inches beneath the preceding; and these are to be con-
nected together by a vertical one carried along the inner side of the thigh (Fig. 338). These
several incisions should divide merely the integument; this is to be reflected outward, when the
superficial fascia will be exposed.
The Superficial Fascia forms a continuous layer over the whole of the thigh,
consisting of areolar tissue, containing in its meshes much fat, and capable of being
separated into two or more layers, between which are found the superficial vessels
and nerves. It varies in thickness in different parts of the limb. In the groin
it is thick, and the two layers are separated from one another by the superficial
inguinal lymphatic glands, the internal saphenous vein, and several smaller
vessels. One of these layers, the superficial, is continuous with the superficial
fascia of the abdomen.
The superficial layer should be detached by dividing it across in the same direction as. the
external incisions; its removal will be facilitated by commencing at the lower and inner angle of
the space, detaching it at first from the front of the internal saphenous vein, and dissecting it
off from the anterior surface of that vessel and its tributaries; it should then be reflected out-
ward in the same manner as the integument. The cutaneous vessels and nerves and superficial
inguinal glands are then exposed, lying upon the deep layer of the superficial fascia. These are
the internal saphenous vein and the superficial epigastric, superficial circumflex iliac, and super-
ficial external pudic vessels, as well as numerous lymphatics, ascending with the saphenous vein
to the inguinal glands.
The internal or long saphenous vein (Figs. 1138, 1139, and 1140) ascends along
the inner side of the thigh, and, passing through the saphenous opening in the
fascia lata, terminates in the femoral vein about an inch and a half below Poupart's
ligament (Fig. 1130). This vein receives at the saphenous opening the superficial
epigastric, the superficial circumflex iliac, and the superficial external pudic veins.
The superficial external pudic artery (superior) arises from the inner side of
the femoral artery, and, after passing through the saphenous opening, courses
inward across the spermatic cord, to be distributed to the integument on the
lower part of the abdomen, the penis and scrotum in the male and the labium in
the female, anastomosing with branches of the internal pudic.
The superficial epigastric artery arises from the femoral about half an inch
below Poupart's ligament, and, passing through the saphenous opening in the
fascia lata, ascends on to the abdomen, in the superficial fascia covering the
External oblique muscle, nearly as high as the umbilicus. It distributes branches
97
1538
THE SURGICAL ANATOMY OF HERNIA
to the superficial inguinal lymphatic glands, the superficial fascia, and the integu-
ment, anastomosing with branches of the deep epigastric and internal mammary
arteries.
The superficial circumflex iliac artery, the smallest of the cutaneous branches,
arises close to the preceding, and, piercing the fascia lata, runs outward, parallel
with Poupart's ligament, as far as the crest of the ilium, dividing into branches
which supply the superficial inguinal lymphatic glands, the superficial fascia, and
the integument of the groin, anastomosing with the deep circumflex iliac, and with
the gluteal and external circumflex arteries.
The Superficial Veins (Fig. 1138). — The veins accompanying these superficial
arteries are usually much larger than the arteries; they terminate in the internal
or long saphenous vein at the saphenous opening.
The superficial inguinal lymphatic glands. — See p. 791.
FIG. 1138. — Femoral hernia. Superficial dissection.
The ilio-inguinal nerve arises from the first lumbar nerve. It escapes at the
external abdominal ring, and is distributed to the integument of the upper and
inner part of the thigh — to the scrotum in the male and to the labium in the
female. The size of this nerve is in inverse proportion to that of the ilio-hypo-
gastric nerve. Occasionally it is very small, and ends by joining the ilio-hypogastric ;
in such cases a branch of the ilio-hypogastric takes the place of the ilio-inguinal,
or the latter nerve may be altogether absent. The crural branch of the genito-
femoral nerve passes along the inner margin of the Psoas muscle, beneath Pou-
part's ligament, into the thigh, entering the sheath of the femoral vessels, and lying
FEMORAL HERNIA
1539
superficial and a little external to the femoral artery. It pierces the anterior layer
of the sheath of the vessels, and, becoming superficial by passing through the fascia
lata, it supplies the skin of the anterior aspect of the thigh as far as midway
between the pelvis and knee. On the front of the thigh it communicates with
the outer branch of the middle cutaneous nerve, derived from the femoral.
The Deep Layer of the Superficial Fascia is a very thin fibrous layer, best marked
on the inner side of the long saphenous vein and below Poupart's ligament. It is
placed beneath the subcutaneous vessels and nerves, and upon the surface of the
fascia lata, to which it is intimately adherent at the lower margin of Poupart's
ligament. It covers the saphenous opening in the fascia lata, is closely united to
its circumference, and is connected to the sheath of the femoral vessels corre-
Fio. 1139. — Femoral hernia, showing fascia lata and saphenous opening.
spending to its under surface. The portion of fascia covering this aperture is
perforated by the internal saphenous vein and by numerous blood- and lymphatic
vessels; hence it has been termed the cribriform fascia, the openings for these
vessels having been likened to the holes in a sieve. The cribriform fascia adheres
closely both to the superficial fascia and to the fascia lata, so that it is described
by some anatomists as a part of the fascia lata, but it is usually considered (as in
this work) as belonging to the superficial fascia. It is not till the cribriform fascia
has been cleared away that the saphenous opening is seen, so that this opening
does not in ordinary cases exist naturally, but is the result of dissection (p. 515). A
femoral hernia in passing through the saphenous opening receives the cribriform
fascia as one of its coverings.
1540
THE SURGICAL ANATOMY OF HERNIA
The deep layer of superficial fascia, together with the cribriform fascia, having
been removed, the fascia lata is exposed.
The Fascia Lata has been already described with the muscles of the front of
the thigh (p. 515). At the upper and inner part of the thigh, a little below
Poupart's ligament, a large oval-shaped aperture is observed after the superficial
fascia has been cleared away; it transmits the internal saphenous vein and other
smaller vessels, and is called the saphenous opening (Fig. 1130). In order the
more correctly to consider the mode of formation of this aperture, the fascia lata in
this part of the thigh is described as consisting of two portions, an iliac portion and
a pubic portion.
FIG. 1140. — Femoral hernia. Iliac portion of fascia lata removed, and sheath of femoral vessels and
femoral canal exposed.
The iliac portion (Fig. 1139) is all that part of the fascia lata on the outer side of
the saphenous opening. It is attached externally to the crest of the ilium and its
anterior superior spine; to the whole length of Poupart's ligament; and to the
pectineal line in conjunction with Gimbernat's ligament. From the spine of the
os pubis it is reflected downward and outward, forming an arched margin, the
outer boundary or falciform process or superior cornu (cornu superius] (Fig. 1139)
of the saphenous opening. This margin overlies and is adherent to the anterior
layer of the sheath of the femoral vessels; to its edge is attached the cribriform
fascia, and below it is continuous with the pubic portion of the fascia lata.
The pubic portion of the fascia lata or the pectineal fascia (Fig. 1139) is situated
at the inner side of the saphenous opening; at the lower margin of this aperture
it is continuous with the iliac portion; traced upward, it covers the surface of
the Pectineus, Adductor longus, and Gracilis muscles; and, passing behind the
FEMORAL HERNIA 1541
sheath of the femoral vessels, to which it is loosely united, is continuous with
the sheath of the Psoas and Iliacus muscles, and is attached above to the ilio-
pectineal line, where it becomes continuous with the fascia covering the Iliacus
muscle. From the description it may be observed that the iliac portion of the
fascia lata passes in front of the femoral vessels and the pubic portion behind
them, so that an apparent aperture consequently exists between the two, through
which the internal saphenous vein joins the femoral vein.
The Saphenous Opening (fossa ovalis) (Figs. 1130, 1138, 1139, and 1140) is an
oval-shaped aperture measuring about an inch and a half in length and half an
inch in width. It is situated at the upper and inner parts of the front of the
thigh, below Poupart's ligament, and is directed obliquely downward and out-
ward. It is covered by the cribriform fascia (fascia cribrosa), a portion of the
deep layer of the superficial fascia of the thigh, and which extends from the
falciform margin to the pubic portion of the fascia lata or the pectineal fascia.
The outer margin of the saphenous opening is of a semilunar form, thin, strong,
sharply defined, and lies on a plane considerably anterior to the inner margin.
If this edge is traced upward, it will be seen to form a curved elongated process,
the falciform process or superior cornu (Fig. 1139), which ascends in front of the
femoral vessels, and, curving inward, is attached to Poupart's ligament and to the
spine of the os pubis and pectineal line, where it is continuous with the pubic por-
tion. If traced downward, it is found continuous with another curved margin,
the concavity of which is directed upward and inward; this is the inferior cornu
of the saphenous opening, and is blended with the pubic portion of the fascia
lata covering the Pectineus muscle.
The inner boundary of the opening (Figs. 1130 and 1139) is on a plane posterior
to the outer margin and behind the level of the femoral vessels; it is much less
prominent and defined than the outer, from being stretched over the subjacent
Pectineus muscle. It is through the saphenous opening that a femoral hernia
passes after descending along the crura! canal.
If the finger is introduced into the saphenous opening while the limb is moved
in different directions, the aperture will be found to be greatly constricted on
extending the limb or rotating it outward, and to be relaxed on flexing the limb
and inverting it; hence the necessity for placing the limb in the latter position in
employing the taxis for the reduction of a femoral hernia.
The iliac portion of the fascia lata, but not its falciform process, should now be removed by
detaching it from the lower margin of Poupart's ligament, carefully dissecting it from the sub-
jacent structures, and turning it inward, when the sheath of the femoral vessels is exposed,
descending beneath Poupart's ligament (Fig. 1140).
Poupart's Ligament (ligamentum inguinale [Pouparti]) (Figs. 288, 1130, 1133,
1134, 1136, 1139, 1140, 1141, and 1142) is the lower border of the aponeurosis
of the External oblique muscle, which extends from the anterior superior spine
of the ilium to the spine of the os pubis. From this latter point it is reflected
outward, to be attached to the pectineal line for about half an inch, forming
Gimbernat's ligament. Its general direction is curved downward toward the thigh,
where it is continuous with the fascia lata. Its outer half is rounded and
oblique in direction. Its inner half gradually widens at its attachment to the
os pubis, is more horizontal in direction, and lies beneath the spermatic cord.
Nearly the whole of the space included between Poupart's ligament and the
innominate bone is filled in by the parts which descend from the abdomen into
the thigh (Figs. 296, 338, and 1141). The outer half of the space (lacuna muscu-
lorum) is occupied by the Iliacus and Psoas muscles, together with the external
cutaneous and femoral nerves. The pubic half of the space (lacuna vasorum)
is occupied by the femoral vessels included in their sheath, a small oval-shaped
interval existing between the femoral vein and the inner wall of the sheath,
1542
THE SURGICAL ANATOMY OF HERNIA
which is occupied merely by a little loose areolar tissue, a few lymphatic vessels,
and occasionally by a small lymphatic gland; this is the femoral ring, through
which the gut descends in femoral hernia. The part of Poupart's ligament in
front of the femoral or crural ring is called the superficial crural arch.
Gimbernat's Ligament (ligamentum lacunare [Gimbernati]) (Figs. 296, 338, 1130,
1141, and 1142) is that part of the aponeurosis of the External oblique muscle
which is reflected backward and outward from the spine of the os pubis, to be
inserted into the pectineal line. It is about half an inch in length, larger in the
male than in the female, almost horizontal in direction in the erect posture, and
of a triangular form, with the base directed outward. Its base or outer margin
is concave, thin, and sharp, and lies in contact with the femoral sheath. Its
apex corresponds to the spine of the os pubis. Its posterior margin is attached to
the pectineal line, and is continuous with the pubic portion of the fascia lata. Its
anterior margin is continuous with Poupart's ligament.
Crural
Poupart's ligament. iranch Femoral
of genito-
femoral.
External
cutaneous nerve.
Iliac portion of
fascia lata.
Femoral vein.
Femoral ring.
Gimbernat's
Femoral arterji.
FIG. 1141. — Structures which pass beneath the crural arch.
Femoral Sheath (Fig. 1141). — The femoral or crural sheath is a continuation down-
ward of the fasciae that line the abdomen, the transversalis fascia passing down in
front of the femoral vessels, and the iliac fascia descending behind them; these
fasciae are directly continuous on the iliac side of the femoral artery, but a small
space exists between the femoral vein and the point where they are continuous on
the pubic side of that vessel, which constitutes the femoral or crural canal (Fig. 1130).
The femoral sheath is closely adherent to the contained vessels about an inch
below the saphenous opening, being blended with the areolar sheath of the vessels,
but opposite Poupart's ligament it is much larger than is required to contain them;
hence the funnel-shaped form which it presents. The outer border of the sheath
FEMORAL HERNIA 1543
is perforated by the femoral nerve. Its inner border is pierced by the internal
saphenous vein and numerous lymphatic vessels. In front it is covered by the
iliac portion of the fascia lata; and behind it is the pubic portion of the same
fascia.
If the anterior wall of the sheath is removed (Fig. 1130), the femoral artery and
vein are seen lying side by side, a thin septum separating the two vessels, while
another septum may be seen lying just internal to the vein, and cutting off a small
space between the vein and the inner wall of the sheath. The septa are stretched
between the anterior and posterior walls of the sheath, so that each vessel is
enclosed in a separate compartment. The interval left between the vein and the
inner wall of the sheath is not filled up by any structure, excepting a little loose
areolar tissue, a few lymphatic vessels, and occasionally by a small lymphatic
gland; this is the femoral or crural canal (Fig. 1130), through which the intestine
descends in femoral hernia.
Deep Crural Arch. — Passing across the front of the femoral sheath on the abdom-
inal side of Poupart's ligament, and closely connected with it, is a thickened band
of fibres of the transversalis fascia, called the deep crural arch. It is apparently a
thickening of the transversalis fascia, joining externally to the centre of Poupart's
ligament, and arching across the front of the crural sheath, to be inserted by a
broad attachment into the pectineal line behind the conjoined tendon. In some
subjects this structure is not very prominently marked, and not infrequently it is
altogether wanting. The superficial crural arch is the portion of Poupart's liga-
ment in front of the femoral ring.
The Femoral or Crural Canal (canalis jemoralis) (Figs. 296, 338, and 1130) is the
narrow interval between the femoral vein and the inner wall of the femoral sheath.
It exists as a distinct canal only when the sheath has been separated from the vein
by dissection or by the pressure of a hernia or tumor. Itsjength is from a quarter
to half an inch, and it extends from the femoral ring to the upper part of the
sa|5nTnbTis openingT
Its anterior wall is very narrow, and formed by a continuation downward of
the transversalis fascia, under Poupart's ligament, covered by the falciform
process of the fascia lata.
Its posterior wall is formed by a continuation downward of the iliac fascia cover-
ing the pubic portion of the fascia lata.
Its outer wall is formed by the fibrous septum separating it from the inner side
of the femoral vein.
Its inner wall is formed by the junction of the processes of the transversalis
and iliac fasciae, which form the inner side of the femoral sheath, and lies in
contact at its commencement with the outer edge of Gimbernat's ligament.
This canal has two orifices — an upper one, the femoral or crural ring, closed by
the septum crurale ; and a lower one, the saphenous opening, closed by the cribri-
form fascia.
The femoral or crural ring (annulus femoralis) (Figs. 1130, 1141, and 1142) is
the upper opening of the femoral canal, and leads into the cavity of the abdomen.
It is bounded in front by Poupart's ligament and the deep crural arch; behind,
by the os pubis, covered by the Pectineus muscle and the pubic portion of the fascia
lata; internally, by the base of Gimbernat's ligament, the conjoined tendon, the
transversalis fascia, and the deep crural arch; externally, by the fibrous septum
lying on the inner side of the femoral vein. The femoral ring is of an oval form;
its long diameter, directed transversely, measures about half an inch, and it is
larger in the female than in the male, which is one of the reasons of the greater
frequency of femoral hernia in the former sex.
POSITION OF PARTS AROUND THE RING. — The spermatic cord in the male and
round ligament in the female lie immediately above the anterior margin of the
1544
THE SURGICAL ANATOMY OF HERNIA
femoral ring, and may be divided in an operation for femoral hernia if the incision
for the relief of the stricture is not of limited extent. In the female this is of little
importance, but in the male the spermatic artery and vas deferens may be divided.
The femoral vein lies on the outer side of the ring.
The deep epigastric artery in its passage upward and inward from the external
iliac artery passes across the upper and outer angle of the crural ring, and is
consequently in danger of being wounded if the stricture is divided in a direction
upward and outward.
The communicating branch between the deep epigastric and obturator lies in
front of the ring.
The circumference of the ring is thus seen to be bounded by vessels in every
part, excepting internally and behind (Fig. 1142). It is in the former position that
the stricture is divided in cases of strangulated femoral hernia.
The obturator artery (p. 689), when it arises by a common trunk with the deep
epigastric (p. 690), which occurs once in every three subjects and a half, bears
a very important relation to the crural ring. In most cases it descends on the
FIG. 1142. — Hernia. The relations of the femoral and internal abdominal rings, seen from within the
abdomen. Right side.
inner side of the external iliac vein to the obturator foramen, and will consequently
lie on the outer side of the crural ring, where .there is no danger of its being
wounded in the operation for dividing the stricture in femoral hernia (Fig. 429 A,
p. 690). Occasionally, however, the obturator artery curves along the free margin
of Gimbernat's ligament in its passage to the obturator foramen; it would conse-
quently skirt along the greater part of the circumference of the crural ring, and
could hardly avoid being wounded in the operation (Fig. 4295, p. 690).
The Crural Septum or Septum Crurale (septum femorale musculus) (Fig. 296).—
The femoral ring is closed by a thin process of transversalis fascia containing fat
and called, by J. Cloquet, the septum crurale. This serves as a barrier to the
protrusion of a hernia through this part. Its upper surface is slightly concave,
and supports a small lymphatic gland (Fig. 1142), by which it is separated from
the subserous areolar tissue and peritoneum. Its under surface is turned toward
the femoral canal. The septum crurale is perforated by numerous apertures for
the passage of lymphatic vessels connecting the deep inguinal lymphatic glands
with those surrounding the external iliac artery.
FEMORAL HERNIA 1545
The size of the femoral canal, the degree of tension of its orifices, and conse-
quently the degree of constriction of a hernia, vary according to the position of
the limb. If the leg and thigh are extended, abducted, or everted, the femoral
canal and its orifices are rendered tense from the traction on these parts by Pou-
part's ligament and the fascia lata, as may be ascertained by passing the finger
along the canal. If, on the contrary, the thigh is flexed upon the pelvis, and at
the same time adducted and rotated inward, the femoral canal and its orifices
become considerably relaxed; for this reason the limb should always be placed in
the latter position when the application of the taxis is made in attempting the
reduction of a femoral hernia.
The subperitoneal areolar tissue is continuous with the subserous areolar tissue
of surrounding parts. It is usually thickest and most fibrous where the iliac ves-
sels leave the abdominal cavity. It covers over the femoral ring, the small interval
on the inner side of the femoral vein. In some subjects it contains a considerable
amount of adipose tissue. In such cases, where it is protruded forward in front
ofJke_§ac^of a Jemoral hernia, it may be migfa.kpn fr>r a portion of omentum. The
peritoneum lining the portion of the abdominal wall between Poupart's ligament
and the brim of the pelvis is similar to that lining any other portion of the abdom-
inal wall, being very thin. Here there is no natural aperture for the escape of
intestine.
Descent of the Hernia. — From the preceding description it follows that the
femoral ring must be a weak point in the abdominal wall; hence it is that when
violent or long-continued pressure is made upon the abdominal viscera a portion
of intestine may be forced into it, constituting a femoral hernia; and the changes
in the tissues of the abdomen which are produced by pregnancy, together with the
larger size of this aperture in the female, serve to explain the frequency of this
form of hernia in women.
When a portion of the intestine passes through the femoral ring, a pouch of
peritoneum lies before it, which forms what is called the hernial sac; it is cov-
ered by the subserous areolar tissue, receives an investment from the septum
crurale, and descends vertically along the crural canal in the inner compartment of
the sheath of the femoral vessels as far as the saphenous opening; at this point it
changes its course, being prevented from extending farther down the sheath on
account of the narrowing of the sheath and its close contact with the vessels, and
also from the close attachment of the superficial fascia and crural sheath to the
lower part of the circumference of the saphenous opening; the hernia is conse-
quently directed forward, pushing before it the cribriform fascia, and then curves
upward on to the falciform process of the fascia lata and lower part of the tendon
of the External oblique, being covered by the superficial fascia and integument.
While the hernia is contained in the femoral canal it is usually of small size,
owing to the resisting nature of the surrounding parts; but when it has escaped
from the saphenous opening into the loose areolar tissue of the groin, it becomes
considerably enlarged. The direction taken by a femoral hernia in its descent is
at first downward, then forward and upward; this should be borne in mind, as
in the application of the taxis for the reduction of a femoral hernia pressure should
be directed in the reverse order.
Coverings of the Complete Hernia. — The coverings of a femoral hernia, from
within outward, are — peritoneum, subserous areolar tissue, the septum crurale,
crural sheath, cribriform fascia, superficial fascia, and integument.1
1 Sir Astley Cooper has described an investment for femoral hernia, under the name of " fascia jpropria." lying
immediately external to the peritoneal sac, but frequently separated from it by more oFTess adipose tissue.
Surgically, it is important to remember the existence (at any rate, the occasional existence) of this layer, on
account of the ease with which an inexperienced operator may mistake the fascia for the peritoneal sac and the
contained fat for omentum. Anatomically, this fascia appears identical with what is called in the text "sub-
nerous argofar flssue," the areolar tissue being thickened and caused to assume a membranous appearanclTBy
the •pressure- ofTtWbernia. — ED. of 15th English edition.
1
1546 THE SURGICAL ANATOMY OF HERNIA
Varieties of Femoral Hernia. — If the hernia descends along the femoral canal only
as far as the saphenous opening, and does not escape from this aperture, the con-
dition is called incomplete femoral hernia. The small size of the protrusion in this
form of hernia, which is due to the firm and resisting nature of the canal in
which it is contained, renders it an exceedingly dangerous variety, from the
extreme difficulty of detecting the existence of the swelling, especially in corpulent
subjects. The coverings of an incomplete femoral hernia, named from without
in ward, are as follows : the integument, superficial fascia, iliac portion of fascia lata,
crural sheath, septum crurale, subserous areolar tissue, and peritoneum. When,
however, the hernia protrudes through the saphenous opening and directs itself
forward and upward, it forms a complete femoral hernia, the coverings of which
have been given (p. 1533). Occasionally the hernial sac descends on the iliac
side of the femoral vessels or in front of these vessels, or even sometimes behind
them.
The seat of stricture in a strangulated femoral hernia varies; it may be in the
peritoneum at the neck of the hernial sac; in the greater number of cases it would
appear to be at the point of junction of the falciform process of the fascia lata
with the lunated edge of Gimbernat's ligament, or at the margin of the saphenous
opening in the thigh. The stricture should in every case be divided in an inward
direction, or upward and inward, and the extent of the necessary cut in the
majority of cases is about two or three lines. By these means all vessels or
other structures of importance in relation with the neck of the hernial sac will
be avoided.
SUEGICAL ANATOMY OF THE PEBDLEUM.
Dissection. —The student should select a well-developed muscular subject, free from fat,
and the dissection should be commenced early, in order that the parts may be examined in as
recent a state as possible. A staff having been introduced into the bladder and the subject
placed in the position shown in Fig. 1143, the scrotum should be raised upward, and retained in
that position, and the rectum moderately distended with tow.
The Perinasum corresponds to the inferior aperture or outlet of the pelvis. Its
deep boundaries are, in front, the pubic arch and subpubic ligament; behind,
the tip of the coccyx; and on each side, the rami of the os pubis and ischium, the
tuberosities of the ischium, and great sacro-sciatic ligaments. The space included
by these boundaries is somewhat lozenge-shaped, and is limited on the surface of
FIG. 1143. — Dissection of perinseum and ischio-rectal region.
the body by the scrotum in front, by the buttocks behind, and on each side by the
inner side of the thigh. A line drawn transversely between the anterior parts of
the tuberosities of the ischium, on each side, in front of the anus, divides this space
into two portions. The anterior portion contains the penis and urethra, and is
called the perinaeum proper or genito -urinary region. The posterior portion con-
tains the termination of the rectum, and is called the ischio-rectal or anal region.
ISCHIO-RECTAL REGION.
The ischio-rectal region contains the termination of the rectum and a deep fossa,
filled with fat, on each side of the intestine, between it and the tuberosity of the
ischium; this is called the ischio-rectal fossa.
The ischio-rectal region presents in the middle line the aperture of the anus;
around this orifice the integument is thrown into numerous folds, which are
obliterated on distention of the anus. The integument is of a dark color, con-
tinuous with the mucous membrane of the rectum, and is provided with numerous
( 1547 )
1548 SURGICAL ANATOMY OF THE PERINEUM
follicles, which occasionally inflame and suppurate, and may be mistaken for
h'stulae. The veins around the margin of the anus are occasionally much dilated,
forming a number of hard pendent masses, of a dark bluish color, covered partly
by mucous membrane and partly by the integument. These tumors constitute the
disease called external piles.
Dissection (Fig. 1143). — Make an incision through the integument, along the median line,
from the base of the scrotum to the anterior extremity of the anus: carry it around the margins
of this aperture to its posterior extremity, and continue it backward to about an inch behind
the tip of the coccyx. A transverse incision should now be carried across the base of the Scrotum,
joining the anterior extremity of the preceding; a second, carried in the same direction, should
be made in front of the anus; and a third at the posterior extremity of the first incision. These
incisions should be sufficiently extensive to enable the dissector to raise the integument from
the inner side of the thighs. The flaps of skin corresponding to the ischio-rectal region should
now be removed. In dissecting the integument from this region great care is required, otherwise
the Corrugator cutis ani and External sphincter will be removed, as they are intimately adherent
to the skin.
The Superficial Fascia is exposed on the removal of the skin; it is very thick,
areolar in texture, and contains much fat in its meshes. In it are found ramifying
two or three branches of the perforating cutaneous nerve; these turn around the
inferior border of the Gluteus maximus and are distributed to the integument
around the anus.
In this region, and connected with the lower end of the rectum, are four muscles :
the Corrugator cutis ani; the two Sphincters, External and Internal; and the
Levator ani.
These muscles have been already described (p. 451).
The Ischio-rectal Fossa (fossa ischiorectalis) (Figs. 299 and 303) is situated
between the end of the rectum and the ischial tuherosity. It is triangular in shape;
its base, directed to the surface of the body, is formed by the integument of the
ischio-rectal region ; its apex, directed upward, corresponds to the point of division
of the obturator fascia and the thin membrane given off from it, which covers the
outer surface of the Levator ani (ischio-rectal or anal fascia). Its dimensions are
about an inch in breadth at the base and about two inches in depth, being deeper
behind than in front. It is bounded, internally, by the Sphincter ani, Levator
ani, and Coccygeus muscles; externally, by the tuberosity of the ischium and the
obturator fascia, which covers the inner surface of the Obturator internus muscle;
in front, it is limited by the line of junction of the superficial fascia with the base
of the triangular ligament; and behind, by the margin of the Gluteus maximus
muscle and the great sacro-sciatic ligament. This space is filled with a large mass
of adipose tissue, which explains the frequency with which abscesses in the neigh-
borhood of the rectum burrow to a considerable depth.
If the subject has been injected, on placing the finger on the outer wall of this
fossa the internal pudic artery, with its accompanying veins and the two divisions
of the nerve, will be felt about an inch and a half above the margin of the ischiatic
tuberosity, but approaching nearer the surface as they pass forward along the
inner margin of the pubic arch. These structures are enclosed in a sheath, the
fascial canal or canal of Alcock (Figs. 303 and 1148), formed by the obturator fascia,
the pudic nerve lying below the artery and the dorsal nerve of the penis above it.
Crossing the space transversely, about its centre are the inferior hemorrhoidal
vessels and nerves, wrhich are distributed to the integument of the anus and to the
muscles of the lower end of the rectum. These vessels are occasionally of large
size, and may give rise to troublesome hemorrhage when divided in the operation
of lithotomy or in that for fistula in ano. At the back part of this space, near
the coccyx, may be seen a branch of the fourth sacral nerve, and at the forepart of
the space the superficial perineal vessels and nerves can be seen for a short distance.
THE PERINEUM PROPER IN THE MALE 1549
THE PERINEUM PROPER IN THE MALE.
The perineal space is of a triangular form; its deep boundaries are limited,
laterally, by the rami of the pubic bones and ischia, meeting in front at the pubic
arch; behind, by an imaginary transverse line extending between the anterior
parts of the tuberosities of the ischia. The lateral boundaries are, in the adult,
from three inches to three inches and a half in length, and the base from two to
three inches and a half in breadth, the average extent of the space being two
inches and three-quarters.
The variations in the diameter of this space are' of extreme interest in connection with the
operation of lithotomy and the extraction of a stone from the cavity of the bladder. In those
cases where the tuberosities of the ischia are near together it would be necessary to make the
incisions in the lateral operation of lithotomy less oblique than if the tuberosities were widely
separated, and the perineal space consequently wider. The perinseum is subdivided by the
median raphe" into two equal parts. Of these, the left is the one in which the operation of lith-
otomy is performed.
In the middle line the perinseum is convex, and corresponds to the bulb of the
urethra. The skin covering it is of a dark color, thin, freely movable upon the
subjacent parts, and covered with sharp crisp hairs, which should be removed
before the dissection of the part is commenced. In front of the anus a prominent
line commences, the raphe", continuous in front with the raphe of the scrotum.
The skin of the raphe' is adherent to the deep layer of the superficial fascia.
Upon removing the skin and the superficial layer of the superficial fascia, in the
manner shown in Fig. 1143, a plane of fascia will be exposed, covering in the
triangular space and stretching across from one ischio-pubic ramus to the other.
This is the deep layer of the superficial fascia or fascia of Colles (fascia superficialis
perinaei}. It has already been described (p. 458). It is a layer of considerable
strength, and encloses and covers a space in which are contained muscles, vessels,
and nerves. It is continuous in front with the fascia of the penis and the dartos
of the scrotum; on each side it is firmly attached to the margin of the ischio-pubic
ramus and to the tuberosity of the ischium; and posteriorly it curves down behind
the Transversalis perinaei muscles to join the base of the triangular ligament.
It is between this layer of fascia and the triangular ligament of the urethra that extravasa-
tion of urine most frequently takes place in cases of rupture of the urethra. The triangular
ligament of the urethra (p. 461) is attached to the ischio-pubic rami, and in front to the subpubic
ligament. It is clear, therefore, that when extravasation of fluid takes place between these
two layers, it cannot pass backward, because the two layers are continuous with each other
around the Transversi perinaei muscles : it cannot extend laterally, on account of the connection
of both these layers to the rami of the os pubis and ischium ; it cannot find its way into the pelvis
because the opening into this cavity is closed by the triangular ligament, and, therefore, so
long as these two layers remain intact, the only direction in which the fluid can make its way
is forward into the areolar tissue of the scrotum and penis, and then on to the anterior wall of
the abdomen.
When the deep layer of the superficial fascia is removed (Fig. 1144), a space is
exposed, between this fascia and the triangular ligament, in which are contained the
superficial perineal vessels and nerves and some of the muscles connected with the
penis and urethra — viz., in the middle line, the Accelerator urinae; on each side,
the Erector penis; and behind, the transversus perinaei; together with the crura
of the corpora cavernosa and the bulb of the corpus spongiosum. Here also is seen
the central tendinous point of the perinaeum. This is a fibrous point in the middle
line of the perinfeum between the urethra and the rectum, being about half an inch
in front of the anus. At this point four muscles converge and are attached — viz.,
the External sphincter ani, the Accelerator urinae, and the two Transversi perinaei
1550
SUMGICAL ANATOMY OF THE PERINEUM
muscles; so that by the contraction of these muscles, which extend in opposite
directions, it serves as a fixed point of support.
The Accelerator urinae, the Erector penis, and the Superficial transversus
perinaei muscles have been already described (p. 459). They form a triangular
space (Fig. 1144). bounded, internally, by the Accelerator urinae; externally, by
the Erector penis; and behind, by the Transversus perinaei. The floor of this
space is formed by the triangular ligament of the urethra; and running from
behind forward in it are the superficial perineal vessels and nerves, and the
transverse perineal artery coursing along the posterior boundary of the space,
on the Transversus perinaei muscle.
The Accelerator urinae and Erector penis should now be removed, when the triangular liga-
ment of the urethra will be exposed, stretching across the front of the outlet of the pelvis. The
urethra is seen perforating its centre, just behind the bulb; and on each side is the crus penis,
connecting the corpus cavernosum with the rami of the ischium and os pubis.
Transversus perinei
superficialis.
GREAT SACRO-
SCIATIC LIGAMENT
Superficial perineal artery.
Superficial perineal nerve.
Internal pudic nerve.
Internal pudic artery.
FIG. 1144. — The superficial muscles and vessels of the perineum.
The Triangular Ligament or the Deep Perineal Fascia (trigonum urogenitale or
diaphragma urogenitale) (Figs. 308, 309, and 1145), which has been already
described (p. 461), consists of two layers, the inferior anterior or superficial layer
(fascia trigoni urogenitalis inferior) of which is now exposed. It is united to the
superior or deep layer behind, but is separated in front by a subfascial space in
which are contained certain structures.
The inferior layer of the triangular ligament (Figs. 304 and 309) consists of a
strong fibrous membrane, the fibres of which are disposed transversely, which
stretches across from one ischio-pubic ramus to the other and completely fills in
the pubic arch; it is attached in front to the subpubic ligament, except just in the
centre, where a small interspace is left for the dorsal vein of the penis. In the erect
position of the body it is almost horizontal. It is perforated by the urethra in the
middle line, and on each side of the urethral opening by the ducts of Cowper's
glands and by the arteries of the bulb; in front, and external to this, by the artery
THE PERINEUM PROPER IN THE MALE
1551
of the corpus cavernosum, immediately before this vessel enters the crus penis.
Near its apex the ligament is perforated by the termination of the pudic artery and
by the dorsal nerve of the penis. The apex of the triangular ligament is known as
the transverse perineal ligament. The crura penis are exposed, lying superficial to
this ligament. They will be seen to be attached by blunt-pointed processes to the
rami of the os pubis and ischium, in front of the tuberosities, and passing forward
and inward, joining to form the body of the penis. In the middle line the bulb and
corpus spongiosum are exposed by the removal of the Accelerator urinae muscle.
If the inferior layer of the triangular ligament is detached on either side,
the deep perineal interspace will be exposed and the following parts will be seen
between it and the deep layer of the ligament: the subpubic ligament in front,
close to the symphysis pubis ; the dorsal vein of the penis ; the membranous por-
tion of the urethra and the Compressor urethrae muscle; Cowper's glands and
their ducts; the pudic vessels and the dorsal nerve of the penis; the artery and
nerve of the bulb and a plexus of veins.
Anterior layer of
deep perineal fascia removed,
shoiving
, COMPRESSOR URETHR/C.
Internal pudic artery.
•Artery of the buU).
-Cowper's gland.
FIG. 1145. — Deep perineal fascia. On the left side the anterior layer has been removed.
The superior, deep, or posterior layer of the triangular ligament or deep perineal
fascia (fascia trigoni urogenitalis superior) (Fig. 304) is derived from the obturator
fascia, and is continuous with it along the pubic arch. Behind, it joins with the
inferior layer of the triangular ligament, and is continuous with the anal fascia.
Above it is the, prostate gland (Fig. 1146), supported by the anterior fibres of
the Levator ani, which act as a sling for the gland and form the Levator prostatae
muscle. The superior layer of the triangular ligament is continuous around the
anterior free edge of this muscle with the layer of recto-vesical fascia covering
the prostate gland. The superior layer of the triangular ligament is perforated
by the urethra. Between the two layers of the triangular ligament are situated
the membranous part of the urethra, enveloped by the Compressor urethrae
muscle (Fig. 309); the ducts of Cowper's glands; the arteries to the bulb; the
pudic vessels and the dorsal nerve of the penis. The membranous part of the
urethra is about three-quarters of an inch in length, and passes downward and
1552
SURGICAL ANATOMY OF THE PERINEUM
forward behind the symphysis pubis, from which it is distant about an inch. It
is the narrowest part of the tube, and is enveloped, as has already been stated,
by the Compressor urethrae muscle.
The Compressor urethrae has already been described (p. 460). In addition to
this muscle, and immediately beneath it, circular muscular fibres surround the
membranous portion of the urethra from the bulb in front to the prostate behind,
and are continuous with the muscular fibres of the bladder. These fibres are
involuntary.
Cowper's glands (Figs. 302, 1145, and 1146) are situated immediately below
the membranous portion of the urethra, close behind the bulb, and below the
artery of the bulb.
The Pudic Vessels (Figs. 1145 and 1146) and Dorsal Nerve of the Penis (Fig. 309)
are placed along the inner margin of the pubic arch (p. 1548).
The Artery of the Bulb (Figs. 1145 and 1146, and p. 692) passes transversely
inward, from the internal pudic artery (p. 690) along the base of the triangular
Avtery of corpus cavernosum
Dorsal artery of penis
Artery of bulb.
Internal pudic artery.
Cowper's gland.
FIG. 1146. — A view of the position of the viscera at the outlet of the pelvis.
ligament, between its two layers, accompanied by a branch of the pudic nerve.
If the superior layer of the triangular ligament is removed and the crus penis of
one side detached from the bone, the under or perineal surface of the Levator
ani muscle, covered by the anal fascia, is brought fully into view (Figs. 301,
302, and 303). This muscle, with the triangular ligament in front and the Coc-
cygeus and Pyriformis behind, closes the outlet of the pelvis.
The Levator ani and Coccygeus muscles have already been described (p. 453).
Position of the Viscera at the Outlet of the Pelvis.— Divide the central tendinous point
of the perinseum, separate the rectum from its connections by dividing the fibres of the Levator
ani, which descend upon the sides of the prostate gland, and draw the gut backward toward the
coccyx, when the under surface of the prostate gland, the neck and base of the bladder, the
vesiculse seminales, and the vasa deferentia will be exposed.
The Prostate Gland (p. 1141) is a pale, firm, glandular body which is placed
immediately below the neck of the bladder, around the commencement of the
THE PERINsEUM PROPER IN THE MALE 1553
urethra. It is placed in the pelvic cavity, behind the lower part of the sym-
physis pubis, above the superior layer of the triangular ligament, and rests upon
the rectum, through which it may be distinctly felt, especially when enlarged. In
shape and size it resembles a chestnut. Its base is directed upward toward the
neck of the bladder. Its apex is directed downward to the deeper layer of the
triangular ligament, which it touches.
Its posterior surface is smooth, marked by a slight longitudinal furrow, and rests
on the second part of the rectum, to which it is connected by areolar tissue. Its
anterior surface is flattened, marked by a slight longitudinal furrow, and placed
about three-quarters of an inch below the pubic symphysis. It measures about
an inch and a half in its transverse diameter at the base, an inch in its antero-
posterior diameter, and three-quarters of an inch in depth. Hence the greatest
extent of incision that can be made in it without dividing its substance completely
across is obliquely backward and outward. This is the direction in which the
incision is made in it in the lateral operation x>f lithotomy. The prostate has a
sheath derived from the recto- vesical fascia (p. 1459).
Above the prostate a small triangular portion of the bladder is seen (Fig. 1147),
bounded, in front and below, by the prostate gland; above, by the recto-vesical fold
of the peritoneum; on each side, by the seminal vesicle and the vas deferens. It is
separated from direct contact with the rectum by the recto-vesical fascia. The
relation of this portion of the bladder to the rectum is of extreme interest to the
surgeon. In cases of retention of urine this portion of the organ is found pro-
jecting into the rectum, between three and four inches from the margin of the
anus, and may be easily perforated without injury to any important parts. This
portion of the bladder was consequently selected in the old days for the perform-
ance of the now obsolete operation of tapping the bladder.
Surgical Anatomy. MEDIAN LITHOTOMY. — As the incision is in the raphe", the hemor-
rhage is trivial, and there is but slight risk of injuring the pelvic fascia. But the operation gives
little room for manipulation and is inadmissible in children, because in them dilatation of the
wound may tear the bladder loose from the urethra. A risk of median lithotomy is division of
the artery of the bulb.
In median lithotomy a grooved staff is introduced, the groove being median. The knife is
introduced in the mid-line, just in front of the anal margin, and hits the staff near the apex
of the prostate; the entire length of the membranous urethra is cut as the instrument is with-
drawn.
PARTS DIVIDED. — Skin, superficial fascia, sphincter ani muscle, central tendon of the
perinseum, inferior leaf of the triangular ligament, membranous urethra, and the Compressor
urethrse muscle.
LATERAL LITHOTOMY.— -The operation is performed on the left side of the perinseum, as this
is most convenient for the right hand of the operator. A grooved staff having been introduced
into the bladder, the first incision is commenced midway between the" anus and the back of
the scrotum (i. e., in an ordinary adult perinaeum about an inch and a half in front of the anus)
a little on the left side of the raphe*, and is carried obliquely backward and outward to midway
between the anus and tuberosity of the left ischium. The incision divides the integument and
superficial fascia, the inferior hemorrhoidal vessels and nerves, and the superficial and trans-
verse perineal vessels. If the forefinger of the left hand is thrust upward and forward into
the wound, pressing at the same time the rectum inward and backward, the staff may be felt in
the membranous portion of the urethra. The finger is fixed upon the staff, and the structures
covering the staff are divided with the point of the knife, which must be directed along the groove
toward the bladder, the edge of the knife being turned outward and backward, dividing in its
course the membranous portion of the urethra and part of the left lobe of the prostate gland
to the extent of about an inch. The knife is then withdrawn, and the forefinger of the left hand
passed along the staff into the bladder. The position of the stone having been ascertained, the
staff is to be withdrawn, and the forceps is introduced over the finger into the bladder. If the
stone is very large, the opposite side of the prostate may need to be -notched before the forceps
is introduced; the finger is now withdrawn, and the blades of the forceps opened and made to
grasp the stone, which must be extracted by slow and cautious undulating movements.
Paris Divided in the Operation. — The various structures divided in this operation are as
follows: the integument, superficial fascia, inferior hemorrhoidal vessels and nerves, and prob-
1554 SURGICAL ANATOMY OF THE PERINEUM
ably the superficial perineal vessels and nerves, the posterior fibres of the Accelerator urinae
muscle, the Transversus perinaei muscle and artery, the triangular ligament, the anterior fibres of
the Levator ani muscle, part of the Compressor urethrae muscle, the membranous and pros-
tatic portions of the urethra, and part of the prostate gland.
Parts to be Avoided in the Operation. — In making the necessary incisions in the perinseum for
the extraction of a calculus the following parts should be avoided : The primary incision should
not be made too near the middle line, for fear of wounding the bulb of the corpus spongiosum
or the rectum; nor too far externally, otherwise the internal pudic artery may be implicated as it
ascends along the inner border of the pubic arch. If the incisions are carried too far forward,
the artery of the bulb may be divided; if carried too far backward, the entire breadth of the pros-
tate and neck of the bladder may be cut through, which allows the urine to become infiltrated
behind the pelvic fascia into the loose areolar tissue between the bladder and rectum, instead
of escaping externally; diffuse inflammation is consequently set up, and peritonitis, from the
close proximity of the recto-vesical peritoneal fold, is the result. If, on the contrary, only the
anterior part of the prostate is divided, the urine makes its way externally, and there is less
danger of infiltration taking place.
During the operation it is of great importance that the finger should be passed into the bladder
before the staff is removed ; if this is neglected, and if the incision made in the prostate and neck
of the bladder is too small, great difficulty may be experienced in introducing the finger afterward;
and in the child, where the connections of the bladder to the surrounding parts are very loose,
the force made in the attempt is sufficient to displace the bladder upward into the abdomen,
out of the reach of the operator. Such a proceeding has not unfrequently occurred, producing
the most embarrassing results and total failure of the operation.
It is necessary to bear in mind that the arteries in the perinseum occasionally take an abnormal
course. Thus the artery of the bulb, when it arises, as sometimes happens, from the pudic
opposite the tuber ischii, is liable in its passage forward to the bulb to be wounded in the
operation of lithotomy. The accessory pudic may be divided near the posterior border of the
prostate gland, if this gland is completely cut across; and if the prostatic veins are of large size,
and give rise, when divided, to troublesome hemorrhage. In men advanced in years the pros-
tatic veins are very apt to be enlarged.
EXTRAVASATION OF URINE. — Extravasation most commonly occurs from urethral rupture,
between Colles's fascia and the triangular ligament of the urethra (extravasation in front of
the triangular ligament). The adherence of these two fascial layers posteriorly prevents the
urine from passing backward. The urine cannot find a way laterally, because both layers on
each side are attached to the rami of the pubes and ischium. It cannot reach the pelvis, because
the triangular ligament bars the way. It can only go forward if the two fascial layers remain
intact, and consequently the urine passes into the areolar tissue of the scrotum beneath the
superficial fascia of the penis and of the anterior abdominal wall.
Pus and blood would pursue the same course in this space. Effusions in this space causes
much pain, because the space contains the three long scrotal nerves.
In rupture of the urethra between the two layers of the triangular ligament, the urine remains
in this situation as long as fascia remains intact. If suppuration occurs, destruction of fascia
liberates the urine.
In rupture behind the superior layer of the triangular ligament (extravasation back of the
triangular ligament), the urine passes into the ischio-rectal fossa and upward and backward
into the pelvis.
THE FEMALE PERINEUM.
The female perinaeum presents certain differences from that of the male, in
consequence of the whole of the structures which constitute it being perforated
in the middle line by the vulvo-vaginal passage.
The Superficial Fascia, as in the male, consists of two layers, of which the
superficial one is continuous with the superficial fascia over the rest of the body,
and the deep layer, corresponding to the fascia of Colles in the male, is, like it,
attached to the ischio-pubic rami, and in front is continued forward through
the labia majora to the inguinal region. It is of less extent than in the male,
in consequence of being perforated by the aperture of the vulva.
On removing this fascia the muscles of the female perinreum, which have
already been described (p. 463), are exposecl (Figs. 310 and 1147). The Sphincter
vaginae, corresponding to the Accelerator urinae in the male, consists of an atten-
THE FEMALE PERINEUM
1555
uated plane of fibres, forming an orbicular muscle around the orifice of the
vagina, instead of being united in a median raphe, as in the male. The Erector
clitoridis is proportionately reduced in size, but differs in no other respect from
the erector penis, and the Transversus perinaei is similar to the muscle of the
same name in the male.
The triangular ligament (Fig. 1147) is not strongly marked as in the male.
It transmits the urethra and the tube of the vagina.
The Compressor Urethrae corresponds with the Compressor urethrae in the male.
It arises from the ischio-pubic ramus, and, passing inward, its anterior fibres blend
with the muscle of the opposite side, in front of the urethra; its middle fibres, the
most numerous, are inserted into the side of the vagina, and the posterior fibres
join the central point of the perinseum.
Suspensory ligament
of clitoris
Glans clitoris
Greater gland
of vestibule,
or gland of
Bartholini
Erector
clitoridie
muscle
Sphincter
vaginae
muscle
Deep perineal
muscle, with
its under
layer of fascia
(the triangular
ligament)
External
obturator
muscle
Sacro-
sciatic
ligament
Glutens maximus
muscle
FIG. 1147. — The female perinaeum after removal of the skin and superficial fascia.
External sphincter
ani muscle
(Bardeleben.)
The distribution of the internal pudic artery is the same as in the male (p. 1552),
and the pudic nerve has also a similar arrangement, the dorsal nerve being,
however, very small and supplying the clitoris.
The corpus spongiosum is divided into two lateral halves, which are represented
by the bulbi vestibuli and partes intermediates.
The Perineal Body fills up the interval between the lower part of the vagina
and the rectum. Its base is covered by the skin lying between the anus and
1556
SURGICAL ANATOMY OF THE PERINEUM
vagina on what is called the perinaeum. Its anterior surface lies behind the pos-
terior vaginal wall, and its posterior surface lies in front of the anterior rectal
wall and the anus. It measures about an inch and a quarter from before back-
ward, and laterally extends from one tuberosity of the ischium to the other. In it
are situated the muscles belonging to the external organs of generation. Through
its centre runs the transverse perineal septum, which is of great strength in women,
and forms on either side, behind the posterior commissure, a hard, ill-defined
body, consisting of connective tissue, with much yellow elastic tissue and inter-
lacing bundles of involuntary muscular fibres, in which the voluntary muscles of
the perinseum are inserted.
THE PELVIC FASCIA (FASCIA PELVIS) (Figs. 303 and 1149).
The pelvic fascia strengthens the floor of the pelvis, fastens pelvic structures
together, and supports the nerves, blood-vessels, and lymphatics. It is connected
above with the transversalis fascia and the iliac fascia. It is at first a thin membrane
Internal pudic vessels_\Ji
and nerve.
Tuberosity of
ischium.
Fia. 1148. — A transverse section of the pelvis, showing the pelvic fascia from behind.
and covers the inner surface of the pelvis, being attached to the brim for a short
distance at the side of the cavity and to the inner surface of the bone around the
attachment of the Obturator internus. At the posterior portion of this muscle it is
continued backward as a very thin membrane in front of the Pyriformis muscle to
the front of the sacrum. In front, as it descends, it gives off the parietal layer of the
pelvic fascia, which continues as the obturator fascia. It then becomes thicker and
covers the inner and upper surface of the Diaphragm of the pelvis as far as the white
line (arcus tendineits fasciae pelvis). The portion covering the superior and upper
surface of the pelvic Diaphragm is the inner sheath of the Levator ani muscle and
is called the visceral layer of the pelvic fascia or the recto-vesical fascia (fascia
diaphragmatis pelvis superior). The white line is a rough band of fascial thick-
ening, seen in the pelvic fascia of each side. It indicates the line of separation
between the pelvic cavity ami the ischio-rectal fossa. It passes from the lower
1557
portion of the symphysis pubis outward and backward to the spine of the ischium.
It makes the attachment of the Levator ani muscle to the pelvic fascia. At the white
line the chief mass of the pelvic fascia passes upon the pelvic viscera and is known
as the fascia endo-pelvica. It covers portions of the vagina, rectum, and urinary
bladder, becomes thinner and thinner, and is gradually lost. Other bands of fascia
begin at the white line, descend on the inner surface of the recto-vesical fascia, and
in the male pass to the tip of the prostate and become the prostatic fascia. Between
the anterior ends of the two white lines the level of the fascia is lower, and it forms
a fossa, bounded on the sides in the male by the pubo-pro static ligaments (liga-
mt-nta puboprostatica lateralia), and in the female by the pubo-vesical ligaments
(ligamenta pubovesicalia lateralia). These ligaments are called the lateral true
ligaments of the bladder. In the base of this fossa in the male runs the anterior true
ligament of the bladder or the pubo-prostatic ligament (ligamentum puboprostaticum
FIG. 1149. — Side view of the pelvic viscera of the male subject, showing the pelvic and perineal fasciae.
medium), and in the female the anterior true vesical ligament (ligamentum pubo-
vesicale medium). These ligaments arise from the lowest portion of the symphysis
and pass to the urinary bladder and prostate in the male, and urinary bladder and
urethra in the female (Spalteholz). The outer surface of the pelvic Diaphragm is
covered by the anal fascia or the ischio-rectal fascia (fascia diaphragmatis pelvis
inferior}. It is the lower or outer sheath of the Levator ani muscle, and is derived
from the obturator fascia. The space between the obturator fascia and the anal
fascia is pyramidal and is called the ischio-rectal fossa (fossa ischiorectalis) .
The pelvic fascia does not completely invest the bladder, although the neck and
lateral walls lie upon the Levator ani muscles, and the lateral true ligaments and
the anterior ligament ascend upon the sides and front of the bladder and are lost
upon the fibrous coat of that viscus. The sides and anterior wall have a fascial
investment. The sheath of the prostate has already been discussed (p. 1459). It is
1558 SURGICAL ANATOMY OF THE PERINEUM
continuous with the recto-vesical fascia and the anterior true ligament of the
bladder.
The pelvic fascia is composed, according to Hughes, of: 1. The fibrous cap-
sules of the pelvic viscera. 2. The sheaths of the Levator ani and Coccygei
muscles (recto-vesical and anal fasciae). 3. The sheath of the Obturator internus
(obturator fascia). 4. Sheath of the Compressor urethrae muscle (the triangular
ligament). 5. The sheath of the pelvic aspect of the Pyriformis muscle. The
sacral plexus is outside this sheath, the internal iliac vessels inside of it.1 As pre-
viously stated, the pelvic fascia gives off the obturator fascia and the recto-vesical
fascia.
The Obturator Fascia (fascia obturatoria) descends and covers the Obturator
internus muscle. It is a direct continuation of the parietal pelvic fascia below
the white line above mentioned, and is attached to the pelvic arch, the ischial
tuberosities, and to the margin of the great sacro-sciatic ligaments. This fascia
forms a canal for the pudic vessels and nerve in their passage forward to the
perinaeum, and gives off a thin membrane which covers the perineal aspect of the
Levator ani muscle, and is called the anal or ischio-rectal fascia. It forms the inner
boundary of the ischio-rectal fossa. From its attachment to the rami of the os
pubis and ischium a process is given off which is continuous with a similar process
from the opposite side, so as to close the front part of the outlet of the pelvis, form-
ing the deep layer of the triangular ligament.
The Recto-vesical Fascia or the Visceral Layer of the Pelvic Fascia
(fascia endopelvica) descends into the pelvis upon the upper surface of the Levator
ani muscle, and invests the prostate, bladder, and rectum. From the inner sur-
face of the symphysis pubis a short rounded band is continued, on each side of
the middle line, to the upper surface of the prostate and neck of the bladder, form-
ing the pubo-prostatic or anterior true ligaments of the bladder. At the side this
fascia is connected to the side of the prostate, enclosing this gland and the vesico-
prostatic plexus of veins, and is continued on to the side of the bladder, forming
the lateral true ligaments of the organ. Another prolongation invests the seminal
vesicle, and passes across between the bladder and rectum, being continuous
with the same fascia of the opposite side. Another thin prolongation is reflected
around the surface of the lower end of the rectum. The Levator ani muscle arises
from the point of division of the pelvic fascia, the visceral layer of the fascia
descending upon and being intimately adherent to the upper surface of the muscle,
while the under surface of the muscle is covered by a thin layer derived from the
obturator fascia, called the ischio-rectal or anal fascia.' In the female the vagina
perforates the recto-vesical fascia and receives a prolongation from it.
1 A Manual of Practical Anatomy. By Prof. Alfred W. Hughes; edited and completed by Dr. Arthur Keith.
CHRONOLOGICAL TABLE
OF
THE DEVELOPMENT OF THE FCETUS.
(FROM BEATJNIS AND BOUCHARD.)
First Week. — During this period the ovum is in the Fallopian tube. Having been fertilized in
the upper part of the tube, it slowly passes down, undergoing segmentation, and reaches
the uterus probably about the end of the first week. During this time it does not undergo
much increase in size.
Second Week. — The ovum rapidly increases in size and becomes imbedded in the decidua, so
that it is completely enclosed in the decidua reflexa by the end of this period. An ovum
believed to be of the thirteenth day after conception is described by Reichert. There was
no appearance of any embryonic structure. The equatorial margins of the ovum were beset
with villi, but the surface in contact with the uterine wall and the one opposite to it were
bare. In another ovum, described by His, believed to be of about the fourteenth day,
there was a distinct indication of an embryo. There was a medullary groove bounded by
folds. In front of this a slightly prominent ridge, the rudimentary heart. The amnion
was formed and the embryo was attached by a stalk, the allantois, to the inner surface of
the chorion. It may be said, therefore, that these parts, the amnion and the allantois. and
the first rudiments of the embryo, the medullary groove, and the heart, are formed at the
end of the second week.
Third Week. — By the end of the third week the flexures of the embryo have taken place, so
that it is strongly curved. The protovertebral disks, which begin to be formed early in the
third week, present their full complement. In the nervous system the primary divisions
of the brain are visible, and the primitive ocular and auditory vesicles are already formed.
The primary circulation is established. The alimentary canal presents a straight tube com-
municating with the yolk-sac. The branchial arches are formed. The limbs have appeared
as short buds. The Wolffian bodies are visible. .
Fourth Week. — The umbilical vesicle has attained its full development. The caudal extremity
projects. The upper and the lower limbs and the cloaca! aperture appear. The heart sep-
arates into a right and left heart. The special ganglia and anterior roots of the spinal
nerves, the olfactory fossae, the lungs and the pancreas can be made out.
Fifth Week. — The allantois is vascular in its whole extent. The first traces of the hands and
feet can be seen. The primitive aorta divides into aorta and pulmonary artery. The duct
of Miiller and genital gland are visible. The ossification of ttie clavicle and the lower jaw
commences. The cartilage of Meckel occupies the first post-oral arch.
Sixth Week. — The activity of the umbilical vesicle ceases. The pharyngeal clefts disappear.
The vertebral column, primitive cranium, and ribs assume the cartilaginous condition. The
posterior roots of the nerves, the membranes of the nervous centres, the bladder, kidney,
tongue, larynx, thyroid body, the germs of teeth, and the genital tubercle and folds
are apparent.
Seventh Week. — The muscles begin to be perceptible. The points of ossification of the ribs,
scapula, shaft of humerus, femur, tibia, palate, and upper jaw appear.
Eighth Week.— The distinction of arm and forearm, and of tnigh and leg, is apparent, as well as
the interdigital clefts. The capsule of the lens and pupillary membrane, the interventricu-
lar and commencement of the interauricular septum, the salivary glands, the spleen, and
suprarenal capsules are distinguishable. The larynx begins to become cartilaginous. All
the vertebral bodies are cartilaginous. The points of ossification for the ulna, radius, fibula,
and ilium make their appearance. The two halves of the hard palate unite. The
sympathetic nerves are now for the first time to be discerned.
1 [Eternod (Anal. Anzeiger, Band xv., 1898) described an ovum which he reconstructed. It
had a precise history, from which he concluded that it must have belonged to the end of the second
or the beginning of the third week. Including the. villi it measured 10 X 8.2 X 6 mm. It was
flattened on its embryonal side, and the embryo measured 1.3 ram. The amnion was completely
formed and the allantois existed as a long canal. The vitelline circulation was established and the
villi of the chorion were beginning to be vascularized. The blastopore still opened into the amniotic
cavity, with the primitive groove behind it and the rudimentary groove in front. The notochord
was closing in and all three layers of the blastoderm were distinct, except around the blastopore, where
they formed an undivided mass. — ED. of loth English edition.]
( 1559 )
1560 THE FCETUS.
Ninth Week. — The corpus striatum and the pericardium are first apparent. The ovary and
testicle can be distinguished from each other. The genital furrow appears. The osseous
nuclei of the bodies and arches of the vertebrae, of the frontal, vomer, and malar bones of the
shafts of the metacarpal and metatarsal bones, and of the phalanges appear. The union of
the hard palate is completed. The gall-bladder is seen.
Third Month. — The formation of the foetal placenta advances rapidly. The projection of the
caudal extremity disappears. It is possible to distinguish the male and female organs from
each other. The cloacal aperture is divided into two parts. The cartilaginous arches on the
dorsal region of the spine close. The points of ossification for the occipital, sphenoid,
lachrymal, nasal, squamous portion of temporal and ischium appear, as well as the orbital
centre of the superior maxillary. The pons Varolii and fissure of Sylvius can be made out.
The eyelids, the hair, and the nails begin to form. The mammary gland, the epiglottis,
and prostate are beginning to develop. The union of the testicle with the canals of the
Wolffian body takes place.
Fourth Month. — The closure of the cartilaginous arches of the spine is complete. Osseous
points for the first sacral vertebra and os pubis appear. The ossification of the malleus and
incus takes place. The corpus callosum, the membrana lamina spiralis, the cartilage of
the Eustachian tube, and the tympanic ring are seen. Fat is first developed in the sub-
cutaneous cellular tissue. The tonsils are seen, and the closure of the genital furrow and
the formation of the scrotum and prepuce take place.
Fifth Month. — The two layers of the decidua begin to coalesce. Osseous nuclei of the axis and
odontoid process, of the lateral points of the first sacral vertebra, of the median points of
the second, and of the lateral masses of the ethmoid make their appearance. Ossification
of the stapes and the petrous bone and ossification of the germs of the teeth take place.
The germs of the permanent teeth and the organ of Corti appear. The eruption of hair on
the head commences. The sudoriferous glands, Brunner's glands, the follicles of the tonsil
and base of the tongue, and the lymphatic glands appear at this period. The differentiation
between the uterus and vagina becomes apparent.
Sixth Month. — The points of ossification for the anterior root of the transverse process of the
seventh cervical vertebra, the lateral points of the second sacral vertebra, the median points
of the third, the manubrium sterni and the os calcis appear. The sacro-vertebral angle
forms. The cerebral hemispheres cover the cerebellum. The papillae of the skin, the
sebaceous glands, and Peyer's patches make their appearance. The free border of the
nail projects from the cqrium of the dermis. The walls of the uterus thicken.
Seventh Month. — The additional points of the first sacral vertebra, the lateral points of the
third, the median point of the fourth, the first osseous point of the body of the sternum,
and the osseous point for the astragalus appear. Meckel's cartilage disappears. The
cerebral convolutions, the island of Reil, and the tubercula quadrigemina are apparent. The
• pupillary membrane atrophies. The testicle passes into the vaginal process of the
peritoneum.
Eighth Month. — Additional points for the second sacral vertebra, lateral points for the fourth
and median points for the fifth sacral vertebrae, can be seen.
Ninth Month. — Additional points for the third sacral vertebra, lateral points for the fifth,
osseous points for the middle turbinated bone, for the body and great cornu of the hyoid,
for the second and third pieces of the body of the sternum, and for the lower end of the
femur appear. Ossification of the bony lamina spiralis and axis of the cochlea takes place.
The eyelids open, and the testicles are in the scrotum.
INDEX.
ABDOMEN, 1241
boundaries of, 1241
fascia of, deep, 435
superficial, 435, 1523
triangular, 1527
lymphatics of, 795, 799
muscles of, 434
deep, 451
dissection of, 434
superficial, 434
surface form of, 450
nerves of, cutaneous, 1014
anterior, 1013
lateral, 1013
ventral, 1013
. intercostal, 1013
regions of, 1243
veins of, 755
viscera, 1245
walls of, apertures in, 1243
lymphatic vessels of, 799
Abdominal aorta, 670
branches of, 673
relations of, 671
surface marking of, 672
surgical anatomy of, 672
aortic plexus, 1089, 1094
intercostal nerves, 1013
muscles, 434
portion of oesophagus, 1236
ring, external, 437, 1526
internal, 448, 1530
pillars of, 1526
sacs, 1246
surface of bladder, 1442
viscera, position of, 1244
Abdomino-aortic glands, 797
Abdomino-thoracic arch, 166
Abducent nerve, 1057
branches of, 1057
nuclei of, 894
relations of, 1058
surgical anatomy of, 1058
Abductor hallucis muscle, 547
indicis muscle, 501
minimi digiti muscle, foot, 548
hand, 500
pollicis muscle, 497
relations of, 498
Aberrant ganglia of spinal nerves,
983
Absorbent glands, 774
Absorbents, 772
Accelerator urinae muscle, 459
Accessorius ad ilio-costalem mus-
cle, 421
Accessory chains to deep cervical
glands, 785
cuneate nucleus, 884
descending palatine canals, 1 16
femoral 'nerve of Winslow,
1020
ganglia of spinal nerves, 983
gland of Rosenmiiller, 1151
ligament of atlas, 278
Accessory nerve, 1073
accessory portion of, 1073
bulbar portion of, 1073
nuclei of, 890
spinal portion of, 1074
surgical anatomy of, 1074
vagal accessory part of, 1073
obturator nerve, 1020
olivary nuclei, 885
parotid gland, 1225
posterior palatine canals, 116,
135
processes, 57
quadrate cartilage, 1107
suprarenal glands, 1438
thyroid glands, 1409
veins, 731
Acetabulum, 220
fossa of, 220
ligaments of, transverse, 332
Acoustic canal, external, 1158
nerve, 1064
nuclei of, 892
surgical anatomy of, 1065
Acrocephalic skull, 146
Acromial angle, 178
region, fascia of, 472
muscles of, 472
surgical anatomy of, 473
thoracic artery, 653
Acromio-clavicular articulation,
301
surface form of, 303
surgical anatomy of, 303
ligament, inferior, 301
superior, 301
Acromion process, 175
Additus glottidis inferior, 1379
Adductor brevis muscle, 523
canal, 699
longus muscle, 522
magnus muscle, 523
minimus muscle, 523
obliquus hallucis muscle, 549
pollicis muscle, 499
transversus hallucis muscle,
551
pollicis muscle, 499
tubercle, 227
Adipose tissue, pads of, 265
Aditus ad antrum, 87, 1160
Adminiculum linea; albte, 439
Afferent nerve, 827
neurone, peripheral axone of,
819
root of spinal cord, 836
vessels of kidneys, 1432
Agminated glands, 1304
Air cells, 1403
sinus, 82
Ala cinerea, 880
nuclei of, 891
lobuli central!*, 897
nasi, 1106
artery of, 609
Ala? cinerea?, nuclei of, 891
of ethmoid, 99
Ala? of sacrum, 64
of vomer, 121, 143
Alar cartilage, greater, 1107
lesser, 1107
ligaments, 280
thoracic artery, 653
Albicantia, 867, 916
Alcock's canal, 1028, 1548
Alimentary canal, 1203
development of, 1247
Alveolar artery, 617
inferior, 616
superior, 617
ducts, 1386
hare-lip, 111
point of skull, 150
processes, 140
of superior maxillary, 109
Alveoli, mucous, 1228
pulmonary, 1386
serous, 1228
of teeth, development of, 1217
Alveus, 937
Amacrine cells, 820
of retina, 1135
Amceblasts, 1216
Ammon's horn, 937
Amphiarthrosis, 266
Ampulla? of Fallopian tube, 1510
membranacea?, 1180
ossea, 1175
tubuli lactiferi, 1518
of Vater, 1352
Amygdala, 871, 954
Amygdaline fissure, 932, 933
Amygdaloid tubercle, 945
Anal canal, 1323
areolar coat of, 1325
mucous membrane of, 1326
muscular coat of, 1324
relations of, 1326
serous coat of, 1324
structure of, 1326
submucous coat of, 1325
fascia, 456, 1558
pockets, 1326
valves, 1326
Anastomosis of arteries, 585
circumpatellar, 710
Anastomotic vein of Trolard, 735
Anastomotica magna of brachial,
658
of femoral, 706
Anatomical neck of humerus, 179
of scapula, 176
Anconeus muscle, 489
Andersch, ganglion of, 1066
Angle, acromial, 178
cephalo-auricular, 1 1 54
of jaw, 124
lateral, inferior, 63
of Luclwig, 166
nasal, 105
of os pubis, 219
of ribs, 163
Rolandic, 926
sacro- vertebral, 61
( 1561 )
1562
INDEX
Angle of skull, 147
of sternum, 157
subscapular, 173
Angular artery, 609
convolution, 931
gyre, 931
process, external, 80, 140
internal, 80, 140
vein, 726
Ankle bone, 246
bursae of, 546
Ankle-joint, articulations of, I
ligaments of, 349
surface form of, 353
surgical anatomy of, 353
Annular ligament of ankle, an-
terior, 544
external, 545
internal, 545
of radius and ulnar, 316
of stapes, 1171
of wrist, anterior, 493
posterior, 495
plexus, 1121
Annul us ciliaris, 1125
ovalis, 569
Ano-coccygeal body of Syming-
ton, 1324
Ansa hypoglossi, 1077
lenticularis, 914, 957
peduncularis, 914, 957
of Vieussens, 1086
Ante-cubital glands, 787
Anterior angle of ribs, 163
annular ligament of ankle, 544
of wrist, 493
atlanto-axial ligament, 276
atlo-axoid ligament, 276
auricular artery, 613
nerves, 1052
bicipital ridge, 181
branches of superior cervical
ganglion, 1085
cardiac plexus, 1090
carpal arch, 661
of ulnar, 665
cerebral artery, 628
chamber of eye, 1139
chondro-sternal ligament, 290
chondro-xiphoid ligament, 290
choroid artery, 630
ciliary arteries, 627
clinoid process, 131
common ligament, 271
communicating artery of ul-
nar, 664
condyloid foramen, 73, 133, 136
fossa, 136
coronary plexus, 1090
costo-vertebral ligament, 286
costo-xiphoid ligament, 290
crescentic lobe of cerebellum,
897
crucial ligament, 339
crural nerve. Sec Femoral
nerve.
deep cervical vein, 733
dental canal, 107
divisions of cervical nerves,
988
of coccygeal nerves, 1025
of lumbar nerves, 1015
of thoracic nerves, 1010
ethmoidal canal, 82, 100
cells, 101
foramen, 82, 130, 141
sinuses, 101
extremity of ribs, 162
facial vein, 726
femoral region, muscles of, 514
fontanelle, 78, 103
Anterior fossa of skull, 130
gluteal line, 216
humeral region, muscles of
476
inferior cerebellar artery, 642
spinous process of ilium, 217
intercostal arteries, 646
veins, 752
internal frontal artery, 628
interosseous artery of ulnar
664
nerve, 1004
intersternal ligament, 292
intertrochanteric line, 225
jugular vein, 728
ligament of Helmholtz, 1170
of malleus, 1170
of wrist, 320
longitudinal ligament, 271
spinal veins, 754
marginal fasciculus, 854
median vein, 736
mediastinal glands, 808
mediastinum, 1396
medullary velum, 901
meningeal artery, 623
nares, 142, 1108
nasal spine, 111, 139, 143
occipito-atlantal ligament, 278
palatine canal, 143
fossa, 110, 133
nerve, 1049
parolfactory sulcus, 935
perforated space, 935
perforating arteries, 646
peroneal artery, 717
phreno-pericardial ligament,
561
pillars of fornix, 950, 951
of soft palate, 1222
pubic ligament, 298
pulmonary nerves, 1072
plexus, 1069, 1072, 1091
radial carpal artery, 661
radio-ulnar ligament, 317
region, muscles of, 481
recurrent tibial artery, 713
region of skull, 139
root of spinal nerves, 982
sacral foramina, 62
sacro-coccygeal ligament, 296
sacro-iliac ligament, 294
sacro-sciatic ligament, 295
scapular region, muscles of,
473
spinal artery, 640
sterno-clavicular ligament, 300
sterno-costal ligament, 290
subarachnoid space, 978
superior dental nerve, 1048
ligament, 287
spinous process of ilium, 216
surface of liver, 1336
of stomach, 1277
temporal artery, 613, 642
diploic vein, 734
thoracic nerve, 1001
tibial artery, 710
gland, 794
nerve, 1033
veins, 758
tibio-fibular region, muscles of,
534
tibio-tarsal ligament, 349
triangle of neck, 618
tubercle of cervical vertebra,
50
tympano-malleolar ligament,
1166
ulnar recurrent artery, 664
vein, 745
Anterior vertebral region, mus-
cles of, 408
vein, 733
wall of tympanum, 1163
Antero-lateral fontanelle, 103
ganglionic arteries, 629
Antero-median ganglionic arte-
ries, 628
Antero-posterior diameter of
pelvis, 210
Antihelix, 1154
fossa of, 1154
Antitragicus muscle, 1157
Antitragus, 1155
Antrum of Highmore, 108
mastoid, 87
opening of, 1163
of pylorus, 1279
tympanic, 87
Anus, 1323
arteries of, 1327
lymphatics of, 807, 1329
nerves of, 1329
veins of, 1328
Aorta, 589
abdominal, 670
arch of, 593
branches of, 595
peculiarities of, 594, 595
relations of, 594
surgical anatomy of, 594
ascending, 590 .
descending, 676
sinus of, great, 591
thoracic, 667
transverse, 592
Aortic isthmus, 593
opening of diaphragm, 431
of heart, 568
semilunar valves, 574
sinus of Valsalva, 575
spindle, 593
vestibule of Sibson, 574
Apertura scalar vestibuli cochleae,
1175
tympanica canaliculi chordae,
1163
Aperture of nose, cartilage of,
1107
Apical coil of cochlea, 1177
glands, 1101
Aponeurosis of external oblique,
435, 1525
of internal oblique, 441
palatine, 406
pharyngeal, 404, 1233
Sibson 's, 1393
of soft palate, 1222
supra-hyoid, 396
vertebral, 413, 418
Apophysis, 34
Appendages of eye, 1 147
of skin, 1195
of uterus, 1509
Appendices epiploicse, 1270
Appendicular artery, 678
vein, 768
Appendiculo-ovarian ligament of
dado, 1312
Appendix of auricle, left, 570
right, 567
ensiform, 159
vermiform, 1311
xiphoid, 159
Aqueduct of mid-brain, 907
central gray, 907
Aquaeductus cochleae, 89, 136
1177
Fallopii, 89
eminence of, 1162
vestibuli, 89, 133, 1175
INDEX
1563
Aqueous chamber, 1138
humor, 1138
Arachnoid of brain, 976
structure of, 978
of cord, 858
structure of, 859
villi, 979
Arangi, body of, 573
Arbor vita; cerebelli, 895, 899
of uterus, 1505
Arboriform cells, 821
Arch of aorta, 593
of atlas, 51
axillary, 415, 466, 648
carpal, anterior, 661
posterior, 661
crural, deep, 450, 1543
superficial, 438, 1541
palmar, deep, 660
superficial, 666
plantar, 719
pubic, 211
supraorbital, 80
tarsal, inferior, 625
superior, 625
of vertebra, 48
zygomatic, 138
Arched commissure of Gudden,
905
Arcuate ligaments, 429, 451
internal, 429
middle, 429
Arcus senilis, 1120
Area cribrosa media, 89
superior, 89
of oblongata, 875
dorsal, 876
lateral, 876
vestibularis, inferior, 1186
superior, 1186
Areolffi of bone, primary, 44
secondary, 45
of mamma, 1516
Areolar coat of anal canal, 1325
of intestine, large, 1325
small, 1298
of liver, 1345
of oesophagus, 1239
of rectum, 1325
of stomach, 1283
tissue, subcutaneous, 1190
subserous, 1256
Arm, arteries of, 639
bones of, 179
fascia? of, 476
deep, 472
superficial, 472
lymphatics of, 787
muscles of, 472, 476
dissection of, 471, 476
surgical anatomy of, 480
nerves of, 994
veins of, 744
Arnold's ganglion, 1053
branches of, 1053
nerve, 1070
canal for, 90
Arteria centralis retinae, 627
magna, 589
Arterise hallucis, 715
princeps cervicis, 611
receptaculi, 623
uterina ovarica, 689
Artery or arteries, 585
alveolar, 617
inferior, 616
superior, 617
anastomosis of, 585
anastomotica magna of brach-
ial, 658
of femoral, 706
Artery or arteries, angular, 609
antero-lateral ganglionic, 629
antero-median ganglionic, 628
aorta, 589
abdominal, 670
arch of, 593
ascending, 590
descending, 667
thoracic, 667
appendicular, 678
arterise receptaculi, 623
articular, of knee, 710
auditory, 641, 1186
auricular, anterior, 613
posterior, 611
axillary, 649
azygos, of knee, 710
of vagina, 688
basilar, 641
brachial, 654
of brain, 630
bronchial, 668
buccal, 616
of bulb, 692
bulbar, 641
calcanean, external, 718
internal, 718
carotid, common, 598
external, 602
internal, 620
carpal arch, anterior, 661
posterior, 661
radial, anterior, 661
posterior, 661
ulnar, anterior, 665
posterior, 665
central ganglionic system, 632
centralis retinae, 627
cerebellar, anterior inferior, 642
posterior inferior, 641
superior, 642
cerebral, anterior, 628
of cerebral hemorrhage, 630
middle, 629
posterior, 642
cervical, ascending, 643
deep, 647
superficial, 644
transverse, 644
choroid, anterior, 630
posterior, 642
ciliary, 627
circle of Willis, 642
circumflex, of arm, 653
iliac, deep, 698
superficial, 704
of thigh, 705
coccygeal, 694
cochlear, 1186
coeliac, 673
colic, left, 680
middle, 678
right, 677
comes nervi ischiadici, 694
mediana, 665
phrenici, 646
communicating, anterior cere-
bral, 628
to deep palmar arch, 666
posterior cerebral, 630
of ulnar, anterior, 664
coronary, 673
of heart, 592
of lip, inferior, 609
superior, 609
of corpus cavernosum, 692
cortical system of, 632
cremasteric, 697
cri co-thyroid, 605
cystic, 676
dental, anterior, 617
Artery or arteries, inferior, 616
posterior, 617
digital, plantar, 661
of ulnar, 666
dorsalis hallucis, 715
indicis, 661
lingua;, 606
nasi, 626
pedis, 713
pollicis, 661
scapulae, 653
dural, 611, 612, 974
epigastric, deep, 697
internal, 697
superficial, 704
superior, 647
ethmoidal, 625
facial, 607
transverse, 613
femoral, 698
common, 700
deep, 704
fibular, superior, 712
of foot, 713
frontal, 613
from anterior cerebral,
628
from middle cerebral, 630
from ophthalmic, 625
ganglionic, postero-lateral, 642
postero-median, 642
gastric, 673, 676
gastro-duodenalis, 675
gastro-epiploica dextra, 675
sinistra, 676
gluteal, 695
inferior, 694
hsemorrhoidal, inferior, 691
middle, 688
superior, 680
of head, 598
of heart, 580
hepatic, 674
histology of, 586
hyoid branch of lingual, 606
of superior thyroid, 605
hypogastric, 685
in fret us, 685
ileo-colic, 677
iliac, circumflex, deep, 698
superficial, 704
common, 683
external, 695
internal, 685
ilio-lumbar, 694
infra-hyoid branch of superior
thyroid, 605
infraorbital, 617
innominate, 596
inosculation of, 585
intercostal, 669
anterior, 646
superior, 647
interlobar, 1432
interosseous, of foot, 715
of hand, 662
ulnar, 664
anterior, 664
posterior, 665
labial, inferior, 609
lachrymal, 624
laryngeal, inferior, 643
superior, 605
lateralis nasi, 609
lenticulo-striate, 630
lingual, 605
deep, 606
of lower extremity, 698
lumbar, 682
lymphatics of, 588
malar from lachrymal, 625
1564
INDEX
Artery or arteries, malledlar
713, 718
mammary, internal, 645
maridibular, 616
marginal, 592
masseteric, 616
mastoid, 611, 612
maxillary, external, 607
internal, 613
mecliastinal, 646
posterior, 668
medicerebellar, 642
medicerebral, 629
medidural, 615
meningeal, 611, 612
anterior, 623
middle, 615
from occipital, 611
from pharyngeal, 612
from vertebral, 640
posterior, 640
small, 616
mesenteric, inferior, 679
superior, 677
metatarsal, 715
of muscle, 364
musculo-phrenic, 646
mylo-hyoid, 616
nasal, from ophthalmic, 626
of septum, 609
naso-palatine, 617
of neck, 598
nerves of, 588
nutrient, of femur, 706
of fibula, 717
of humerus, 658
of tibia, 718
obturator, 689
occipital, 610
resophageal, 643, 668
ophthalmic, 624
orbital, 613
internal, 629
ovarian, 682
palatine, ascending, 608
descending, 617
inferior, 608
posterior, 617
palmar arch, deep, 660
superficial, 666
palpebral, 625
pancreatic, 676
pancreatico-duodenalis, infe-
rior, 677
superior, 676
parietal, 613
ascending, 630
parieto-sphenoidal, 630
parieto-temporal, 630
parvidural, 616
of penis, dorsal, 691, 1468
perforating, anterior, 646
of foot, 719
of hand, 662
of thigh, 706
pericardiac, 646, 668
of pericardium, 563
perineal, superficial, 691
transverse, 692
peroneal, 717, 718
pharyngeal, ascending, 612
phrenic, inferior, 682
superior, 646
of pi a of brain, 982
plantar, 718, 719
popliteal, 707
postcerebellar, 641
postce'rebral, 642
postchoroid, 642
postcomniunicant, 630
postdural, 612
Artery or arteries, postero-
lateral ganglionic, 642
postero-median ganglionic, 630
precerebellar, 642
precerebral, 628
prechoroid, 630
precommuiiicant, 628, 629
predural, 623
prevertebral, 612
princeps hallucis, 715
pollicis, 662
profunda, of arm, inferior, 658
superior, 657
femoris, 704
pterygo-palatine, 617
pterygoid, 616
pudic, accessory, 691
external, 704
internal, in female, 693
in male, 690
pulmonary, 589
pyloric, inferior, 675
superior, 675
radial, 659
radialis indicis, 662
ranine, 606
recurrent, palmar, 662
radial, 661
tibial, anterior, 713
posterior, 712
ulnar, anterior, 664
posterior, 664
renal, 680
inferior, 1432
of round ligament, 689
sacral, lateral, 694
middle, 683
scapular, posterior, 644
sciatic, 693
sigmoid, 680
spermatic, 681
spheno-palatine, 617
spinal, anterior, 640
dorsal, 641
lateral, 640
posterior, 641
rami, 640
ventral, 640
splenic, 676
sternal, 646
sterno-mastoid, 605, 611
stylo-mastoid, 611
subclavian, 633
subcostal, 669
sublingual, 606
submaxillary, 608
submental, 608
subscapular, 653
superficialis volse, 661
supra-acromial, 644
supra-hyoid, 606
supraorbital, 625
suprarenal, 680
suprascapular, 643
suprasternal, 644
sural, 709
tarsal, 714
temporal, 612, 613
anterior, 613, 642
deep, 616
middle, 613
posterior, 613, 642
terminal, 632
thoracic, acromial, 653
alar, 653
long, 653
superior, 651
thyroid axis, 642
inferior, 643
superior, 604
of thyroid gland, 605
Artery or arteries, thyroidea
ima, 596
tibial, anterior, 710
posterior, 715
recurrent, anterior, 713
posterior, 712
tonsillar, 608
tracheal, 643
transversalis colli, 644
humeri, 643
of trunk, 667
tympanic, from ascending
pharyngeal, 612
from internal carotid, 623
from internal maxillary, 615
ulnar, 662
recurrent, anterior, 664
posterior, 664
umbilical, in foetus, 583, 686
of upper extremity, 633
uterine, 688
vaginal, 688
of vas deferens, 687
vasa brevia, 676
intestini tenuis, 677
vasorum of, 588
vertebral, 639
vesical, inferior, 688
middle, 688
superior, 687
Vidian, 617
Arthrodia, 268
Arthrology, 261
Articular arteries of knee, 710
inferior, 710
superior, 710
cartilage, 262
circumference of ulna, 191
corpuscles, 830
eminence of temporal bone, 84
lamella of bone, 261
processes of a vertebra, 49
synovial membrane, 264
Articulations, 261
acromio-clavicular, 301
of ankle-joint, 349
astragalo-scaphoid, 356
atlanto-axial, 276
of atlas with axis, 276
with occipital bone, 278
biaxial, 267
.calcaneo-astragaloid, 354
calcaneo-cuboid, 355
calcaneo-scaphoid, 355
carpo-metacarpal, 323
of carpus, 321
chondro-sternal, 290
coccygeal, 296
condyloid, 267
costo-central, 285
costo-chondral, 292
costo-sternal, 289
costo-transverse, 287
costo- vertebral, 285
crico-arytenoid, 1375
crico-thyroid, 1375
of cuboid with cuneiform, 358
with scaphoid, 357
of elbow-joint, 310
femoro-tibial, 337
of hip, 327
immovable, 266
interchondral, 291
interneural, 274
of knee, 336
of lower extremity, 327
jaw, 282
metacarpo-phalangeal, 326
metatarso-phalangeal, 361
mixed, 266
movable, 267
INDEX
1565
Articulations, occipito-atlantal
278
occipito-axial, 280
of ossa pubis, 298
of ossicles of tympanum, 1170
of pelvis, 294
of phalanges of foot, 361
of hand, 327
radio-carpal, 319
radio-ulnar, 315
inferior, 317
middle, 316
superior, 316
by reciprocal reception, 267
of ribs with vertebrae, 285
sacro-coccygeal, 266
sacro-iliac, 294
sacro-sciatic, 294
sacro- vertebral, 292
of sacrum with coccyx, 296
and ilium, 294
and ischium, 294
scapulo-clavicular, 301
of shoulder-joint, 305
of spine with cranium, 278
sterno-clavicular, 299
of sternum, 292
tarso-metatarsal, 359
of tarsus, 354
temporo-mandibular, 282
temporo-maxillary, 138
tibio-fibular, 347
tibio-tarsal, 349
of trunk, 271
of upper extremity, 299
of vertebral column, 271
with pelvis, 292
of wrist, 319
Articuli, 954
Aryteno-epiglottidean folds, 1373
Aryteno-epiglottideus muscle,
1381
Arytenoid cartilages, 1372
apex of, 1373
base of, 1373
surfaces of, 1372
glands, 1383
muscles, 1380
Arytenoideus muscle, 1380
Ascending aorta, 590
• branches of, 592
relations of, 591
cervical artery, 643
colon, 1317
hepatic flexure of, 1317
frontal artery, 630
lumbar vein, 753, 765
right, 752
mesocolon, 1268
oblique muscle of abdomen,
439
palatine artery, 608
parietal artery, 630
pharyngeal artery, 612
projection nerve fibres, 963
ramus of ischium, 218
of pubis, 219
root of fifth nerve, 1042
vena cava, 764
Association fibres of cerebellum,
902, 961
Asterion, 75, 138, 150
Astragalo-scaphoid articulation,
356
ligament, superior, 356
Astragalus, 246
articulations of, 248
body of, 246
head of, 246
neck of, 246
surfaces of, 246, 247
Astrocytes, 832
Atlanto-axial ligament, anterior,
276
posterior, 277
Atlanto-odontoid joint of Cru-
veilhier, 276
Atlas, 50
arches of, 51
attachment of muscles to, 60
development of, 59
lateral masses of, 51
processes of, 51
transverse ligament of, 277
Atlo-axoid ligament, anterior,
276
posterior, 277
Atrabiliary capsules, 1439
Atria of left bronchus, 1386
Atrium, 1160
of nasal fossae, 1110
meat us, 145
Attic, 1160
tympanic, 87
Attollens auriculam muscle, 371
Attrahens auriculam muscle,372
Auditory arteries, 641, 1186
canal, external, 1158
meat us, external, 138, 1158
arteries of, 1159
cartilaginous portion of,
1158
lymphatics of, 1160
nerves of, 1160
osseous portion of, 1159
relations of, 1159
skin of, 1159
surface form of, 1160
veins of, 1160
internal, 133
fundus of, 1178'
nerve, 1064, 1186
surgical anatomy of, 1065
nuclei, dorsal, 892
ventral, 892
process, 88
radiation, 956
teeth, 1183
veins, 1186
Auerbach's plexus, 1307
Aula, 917
Aulix, 916
Auricle of ear, 1154
of heart, fibres of, 577
left, 570
sinus of, 570
right, 567
sinus of, 567
Auricular appendices, 567
appendix, left, 570
right, 567
artery, anterior, 613
posterior, 611
branch of vagus nerve, 1070
fissure, 90, 136
nerves, anterior, 1052
great, 989
posterior, 1062
point of skull, 150
region, muscles of, 371
dissection of, 371
surface of sacrum, 63
vein, 727
Auriculo-temporal nerve, 1052
Auriculo- ventricular fasciculus of
heart, 579
groove of heart, 567
opening, left, 571
right, 568
Axes of pelvis, 211
Axilla, dissection of, 465
surgical anatomy of, 647
Axilla, suspensory ligament of,
466
Axillary arch, 415, 466, 648
artery, 649
branches of, 652
peculiarities of, 651
relations of, 650
surface marking of, 651
surgical anatomy of, 651
border of scapula, 176
fascia, 465, 648
glands, 787
space, 647
veins, 747
surgical anatomy of, 748
Axis, 52
apex of, 52
attachment of muscles to, 60
body of, 52
cerebro-spinal, 833
coeliac, 673
cylinder process, 820
medullated, 824
development of, 59
ligament of malleus, 1171
odontoid process of, 52
optic, 1115
pedicles of, 52
processes of, 53
thoracic, 653
thyroid, 642
visual, 1116
Axone of cord, myelinization%of,
855
myelinic, 824, 826
of nerve-cells, 816, 820, 823
peripheral, of afferent neu-
rone, 819
termination of, 828
varieties of, 824
Azygos arteries, articular, 710
of vagina, 688
uvulae muscle, 407
veins, 752
larger, 752
left lower, 753
upper, 753
right, 752
smaller, 753
surgical anatomy of, 753
B
BACK, fascia of, deep, 413
superficial, 413
muscles of, dissection of, 422
fifth layer, 422
first layer, 412
fourth layer, 419
second layer, 416
surface forms of, 426
third layer, 417
Baillarger, fibre band of, 959
Band, fibre, of Baillarger, 959
of Bechterew, 959
of Gennari, 959
of Meckel, 1170
of Vicq d'Azyr, 939
Bartholin, duct of, 1227
glands of, 1495
Basal ganglia, 867, 952
Base of sacrum, 64
of skull, 130
surfaces of, 130
Basi-hyal of hyoid bone, 155
Basil coil of cochlea, 1177
Basilar artery, 641
branches of, 641
groove, 75
of pons, 877
1566
INDEX
Basilar lymph-sinus, 1314
membrane of cochlea, 1182
process, 71
sinus, 743
suture, 128
vein, 735
Basilic vein, 746
median, 746
Basion, 73, 150
Basis vertebrarum, venae, 753
Basisylvian fissure, 924
Basket-cells of cerebellum, 902
Bauhin, valve of, 1315
Beaunis et Bouchard, table of
development of fostus, 1559
Bechterew, fibre band of, 959
Bell, respiratory nerve of, exter-
nal, 1000
internal, 992
Bertin, bones of, 97
columns of, 1424
ligaments of, 330
Biaxial articulation, 267
Biceps flexor cubiti muscle, 477
muscles, 477, 532
bursa of, 477
Bicipital fascia, 478, 746
groove, 179
ridges, 181
tuberosity, 191
Bicornate uterus, 1505
Bicuspid teeth, 1208
yalve, 574
cusps of, 574
Bigelpw, ligament of, 330
Bile, 1353
Bile-canaliculi, 1348
Bile-capillaries, 1348
Bile-duct, common, 1351
arteries of, 1353
dimensions of, 1353
lymphatics of, 803, 1353
nerves of, 1353
structure of, 1352
surgical anatomy of, 1355
veins of, 1353
papilla, 1296
Bipeiiniform muscles, 365
Bipolar cells, 820
"Bird's nest" of cerebellum,
898
Biventer cervicis muscle, 422
Bi ventral lobe of cerebellum, 898
Bladder, 1441
apex of, 1445
arteries of, 1449
base of, 1443
body of, 1443
cervix of, 1444
female, 1455
fundus of, 1443
ligaments of, 1445
lymphatics of, 800, 1449
mucous coat of, 1447
membrane of, 1447
muscular coat of, 1446
neck of, 1444
nerves of, 1449
serous coat of, 1446
structure of, 1446
submucous coat of, 1447
summit of, 1445
surface form of, 1449
surfaces of, 1442
inner, 1447
surgical anatomy of, 1449
trigone of, 1447
veins of, 1449
Blade bone, 172
Blind spot, 1131
Blood-vascular system, 557
Bochdalek, ganglion of, 1048
Bodies, parasympathetic, 1417
Body, carotid, 1416
cavernous, artery of, 692
coccygeal, 1417
of lungs, 915
pineal, 915
pituitary, 917
thyroid,' 1407
of a vertebra, 49
Bones, acetabulum, 220
apophysis of, 34
areolse of, primary, 44
secondary, 45
astragalus, 246
atlas, 50
axis, 52
of Bertin, 97
blood-vessels of, 39
breast, 157
calcaneum, 242
canaliculi of, 46
cancellous, 35
carpus, 195
chemical composition of, 41
clavicle, 169
coccyx, 65
compact, 35
cranial, 71
cuboid, 248
cuneiform of foot, 249
of hand, 199
diploe of, 34
ear, 1168
eminences and depressions of,
34
epactal, 103
epicteric, 103
epiphysis of, 34
ethmoid, 98
of face, 104
femur, 223
fibula, 239
flat, 34
of foot, 244
frontal, 79
growth of, 42
of hand, 195
Haversian canals of, 38
systems of, 38
humerus, 179
hyoid, 155
ilium, 214
incus, 1169
inter-maxillary, 110
irregular, 34
ischium, 217
of jaw, changes produced in,
by age, 112
lachrymal, 112
lacunae of, 38
lamella of, 38
articular, 261
of leg, 233
lingual, 155
long, 33
lymphatics of, 41
malar, 113
malleus, 1168
marrow of, 36
maxillary, inferior, 122
superior, 105
medullary spaces of, 45
metacarpal, 200
metatarsal, 252
mixed, 34
nasal, 104
navicular, 197, 249
nerves of, 41
occipital, 71
orbicular, 1169
Bones, os calcis, 244
innominatum, 213
magnum of carpus, 201
ossification of, 42
intracartilaginous, 43
intramembranous, 43
palate, 115
parietal, 76
patella, 233
pelvic, 209
periosteum of, 37
phalanges of foot, 255
of hand, 206
pisiform, 199
ploughshare, 120
pre-maxillary, 110
pubis, 219
radius, 192
ribs, 161
sacrum, 61
scaphoid of foot, 249
of hand, 197
scapula, 172
semilunar, 198
sesamoid, 259
short, 33
sphenoid, 92
spongy, 97
sternum, 157
structure, 34
supernumerary, 103
surface of, 34
sutural, 103
tarsus, 244
temporal, 83
thigh, 223
tibia, 234
trapezium, 200
trapezoid, 200
turbinated, inferior, 119
middle, 101
sphenoidal, 143
superior, 101
tympanic, 91
ulna, 186
unciform, 201
veins of, 41
vertebra prominens, 53
vertebra, cervical, 49
lumbar, 56
thoracic, 53 .
vomer, 120
wedge, 249
Wormian, 103
Bony canal of cochlea, 1177
Bosom, 1516
Bowman's capsule, 1427
glands, 1111
membrane, 1119
muscle, 1125
Brachia of quadrigemina, 905
Brachial artery, 654
branches of, 657
peculiarities of, 655
relations of, 654
surface marking of, 656
surgical anatomy of, 656
lymphatic glands, 787
plexus, 994
branches of, 998
relations of, 998
surgical anatomy of, 1009
region, anterior, muscles of, 481
posterior, muscles of, 488
veins, 747
Brachialis anticus muscle, 478
Brachio-cephalic vein, 750
Brachycephalic skull, 146
Brain," 860
adult human, descriptive an-
atomy of, 873
INDEX
1567
Brain, arachnoid of, 976
villi of, 975)
areas of localization of, 966
blood-vessels of, 630
convolutions of, 922
cortex of, 871
development of, 863
dimensions of, 862
dura of, 972
fissures of, 922, 923
fore-, 911
ganglionic vessels of, 632
gyres of, 922
hemispheres of, 989
hind-, 874
laminae of, 870
little, 895
lobes of, 923
localization of function of, 966
meninges of, 972
mill-, 904
Pacchionian bodies of, 979
pia of, 980
sand, 915
smell-, 920
topography of, 860
tube, flexures of, 869
ventricles of, 869, 878
vesicles of, 864
weight of, 965
zones of, longitudinal, 870
Breast bone, 157
Bregma, 129, 150
Bregmatic fontanelle, 103
Breschet, canals of, 733
Brim of pelvis, 209
Broad ligaments of liver, 1340
of uterus, 1502
Broca, "cap" of, 925
diagonal band of, 936
Bronchi, 1384
Bronchial arteries, 668
branch of innominate, 596
glands, 1389
septum, 1389
veins, 753
Bronchus, left, 1386
right, 1384
Brown striae of Retzius, 1214
Bruce and Campbell's tract of
cord, 853
Bruch, membrane of, 1124
Brunner's glands, 1303
Bubonocele, 1533
Buccal artery, 616
cavity, 1203
glands, 1205
lymphatic glands, 781
nerve, 1051, 1063
Buccinator crest, 124
glands, 781
muscle, 382
nerve, 1051
veins, 726
Bucco-pharyngeal fascia, 383,
390, 403, 1232
Bulb, artery of, 692
surgical anatomy of, 692
of cornu, 946
of corpus cavernosum, 1467
spongiosum, 1468
of internal jugular vein, 729
nerve to, 1030
occipital, 946
olfactory, 867, 934
spinal, 874
of urethra, male, 1468
vaginal, 1495
Bulbar arteries, 641
portion of accessory nerve,
1073
Bulbar portion of conjunctiva
1150
Bulbo-cavernous muscle, 459
Bulboid corpuscles, 830
Bulbous vestibuli, 1495
Bulla ethmoiclalis, 145, 1109
Bundle of Helwig, 886
of His, 579
of Vicq d'Azyr, 914, 916
Burdach, column of, 840, 850
Burns, falciform margin of, 517
space of, 389
Bursae of ankle, 546
anserina, 533
of biceps muscle, 477
of coraco-brachialis muscle
477
of elbow, 313
of extensor carpi radialis bre-
vior muscle, 488
of foot, 546
of gastrocnemius muscle, 537
of great trochanter, 333
gluteo-femoral, 333
of hand, 494
of hip, 332
iliac, 333
ilio-pectineal, 332
infrapatellar, 342
infraspinatus, 307, 475
ischio-gluteal, 333
of knee, 342
of latissimus dorsi muscle
476
obturator, 333
internus muscle, 528
olecranon, 313
patellar, 521
pharyngeal, 1234
prepatellar, 342
of pyriformis muscle, 528
of semimembranous muscle,
534
of shoulder, 307
sterno-hyoid, 394
subacromial, 307, 473
subcutanea prominentiae laryn-
geae, 1370
subcutaneous acromial, 307
olecranon, 479
synovial, 265
tibial, 342
trochanteric, 333
subdeltoid, 307, 473
subscapular, 307, 473
subtendinous iliac, 333
synovial, 265
suprapatellar, 342
of tendo Achillis, 538
theca synovial, 265
of tibialis anticus muscle, 535
wrist, 494
Bursal synovial membrane, 265
CACUMINAL lobe of cerebellum
898
Csecal fold, inferior, 1273
superior, 1273
Caecum, 1308
arteries of, 1315
interior of, 1310
lymphatics of, 1314
supports of, 1310
veins of, 1313
vestibulare, 1180
Ca-lurn, 1246
Cajal, horizontal cells of, 1135
Calamus scriptorius, 879
Calcaneal nerves, lateral, 1031
medial, 1031
Calcanean artery, external, 718
internal, 718
Calcaneo-astragaloid ligament,
external, 354
internal, 354
posterior, 354
Calcaneo-cuboid ligament, inter-
nal, 355
long, 355
short, 355
superior, 355
Calcaneo-navicular ligament, 355
Calcaneo-plantar nerve, 1031
Calcaneo-scaphoid ligament, ex-
ternal, 355
inferior, 356
internal, 356
superior, 355
Calcaneus, 244
articulations of, 246
attachment of muscles to, 246
body of, 244
extremities of, 244
processes of, 245
surfaces of, 244, 245
tuberosity of, 246
Calcar, 946
femorale, 229
Calcarine fissure, 926
Calf bone, 239
Calices of kidney, 1424
Callosal gyre, 928, 930
Callosum, 920, 939
body of, 940
development of, 941
genu of, 940
peduncles of, 936
splenium of, 920
tapetum of, 945
Calvaria, 71
Camper, fascia of, 435
Canaliculi of bone, 46
Canaliculus tympanicus, 1161
Canalis centralis cochleae, 89
reuniens of Hensen, 1180
spiralis modioli, 1177
Canals, acoustic, external, 1158
adductor, 699
Alcock's, 1028, 1548
alimentary, 1203
anal, 1323
of appendix, 1312
for Arnold's nerve, 90
auditory, external, 1158
of Breschet, 733
carotid, 136
cervical, 1503
of Cloquet, 1139
of cochlea, 1177
membranous, 1182
of cord, central, 845
cranio-pharyngeal, 917
crural, 1543
dental, 1212
anterior, 107
inferior, 124
posterior, 106
diploic, 733
ethmoidal, 82, 100
for Eustachian tube, 1164
fascial, 1548
femoral, 511, 1543
Haversian, 38
of Huguier, 84, 1062
Hunter's, 524, 699
hyaloid, 1139
incisor, 110
infraorbital, 107, 140
inguinal, 450, 1529
1568
INDEX
Canals for Jacobson's nerve, 90
lachrymal, 1152
malar, 114
naso-palatine, 121
neurenteric, 1252
of Xuck, 1472, 1513
obturator, 528
palatine, anterior, 143
posterior, 107, 116
accessory, 116, 135
palato-maxillary, 107
of Petit, 1140
pterygo-palatine, 135
pterygoid, 135
sacral, 6.4
of Schlemm, 1118, 1121
semicircular, 1 175
spermatic, 450, 1529
spinal, 69
of Stilling, 1139
for tensor tympani, 91, 1163
vertebral, 49
Vidian, 96, 135
Volkmann's, 38
of Wirsung, 1359
Cancellous bone, 35
lamellae of, 39
Canine eminence, 106
fossa, 106, 140
teeth, 1207
Canthi of eyelids, 1148
"Cap" of Broca, 925
Capillaries, histology of, 586
Capitellum of humerus, 183
Capsular liaments. See Indi-
vidual joints.
Capsules, atrabiliary, 1439
Bowman's, 1427
cartilage, 262
external, 957
of Glisson, 770, 1266, 1344
internal, 955
of kidneys, fatty, 1419
true, 1423
of lens, 1140
parotid, 1226
of prostate gland, 1459
suprarenal, 1437
of Tenon, 1113
Caput gallinaginis, 1451
Cardia, 1278
Cardiac depression of liver, 1336
ganglion of Wrisberg, 1090
glands, 1286
lymphatics, 812
muscular fibres, 363
nerve, cervical, 1072
great, 1086
inferior, 1086
middle, 1086
minor, 1086
plexus of, 1090
anterior, 1090
deep, 1090
great, 1090
superficial, 1090
superior, 1085
thoracic, 1072
orifice of stomach, 1278
portion of stomach, 1277
veins, 770
anterior, 771
great, 770
left, 771
middle, 771
posterior, 771
right, 771
Cardio-motor nerves, 1081
Carina urethralis vaginae, 1496
Carotico-tympanic nerve, 1083
Carotid arteries, common, 598
Carotid arteries, common
branches of, 601
peculiarities of, 601
relations of, 600
surface form of, 601
surgical anatomy of, 601
external, 602
branches of, 604
relations of, 603
surface form of, 603
surgical anatomy of, 603
internal, 620
branches of, 623
cavernous portion, 622
cerebral portion, 623
cervical portion, 621
peculiarities of, 623
petrous portion, 622
relations of, 622
surgical anatomy of, 623
body, 1416
canal, 136
foramen, external, 89
internal, 88
ganglion, 1083
gland, 785, 1416
surgical anatomy of, 1407
groove, 93
nerves, 1067
plexus of, 1083
sheath, 390
triangle, inferior, 618
superior, 396, 619
tubercle, 51
Carpal arch, anterior, 661
posterior, 661
artery, radial, anterior, 661
posterior, 661
ulnar, anterior, 665
posterior, 665
bones, development of, 207
Carpo-metacarpal articulations,
323
Carpus, 195
articulations of, 321
common characters of, 195
ligaments of, 321
surface form of, 206
surgical anatomy of, 207
Cartilage, 261
accessory quadrate, 1107
alar, 1107
of aperture of nose, 1107
articular, 262
arytenoid, 1372
capsule, 262
costal, 164
cricoid, 1371
cuneiform, 1373
of ear, 1156
elastic, 262
ensiform, 157
of epiglottis, 1373
epiphyseal, 36, 44
fibro-, 262
hyaline, 262
intrathyroid, 1371
of Jacobson, 1107
of larynx, 1370
of nose, 1106
permanent, 261
of pinna, 1156
of Santorini, 1373
sesamoid, 1107
spaces, 262
temporary, 261
thyroid, 1370
of "trachea, 1386
triangular, of septum of nose,
1107
yomerine, 1107
Cartilage of Wrisberg, 1373
xiphoid, 157
Cartilaginous isthmus of pinna,
1156
portion of Eustachian tube,
1164
of external auditorv meatus,
1158
Cartilago triticea, 1373
Caruncle, lachrymal, 1150, 1152
Caruncula lacrimalis, 1150, 1152
of Santorini, 1296
Caruncula? mystiforma?, 1492
Casserius, perforating nerve of,
1002
Cauda equina, 836, 1023
helicis, 1156
Caudal gut, 1252
Caudate lobe of liver, 1340
nucleus, 953
Cauda turn, 953
Cava, ascending, 764
inferior, 764. See Postcava.
superior, 752. See Precava.
Cave of Meckel, 973, 1042
Cavernous body, artery of, 692
groove, 93
nerves of penis, 1095
plexus, 1083
portion of internal carotid ar-
tery, 622
of urethra, 1452
sinus, 739
surgical anatomy of, 740
Cavity, buccal, 1203
of cervix uteri, 1503
cotyloid, 220
glenoid, 176
of larynx, 1376
of Meckel, 973
of mouth, 143
nasal, 142
oral, 1203
of pelvis, 1440
pericardiothoracic, 1246
of pleura, 1391
pleuroperitoneal, 1246
sigmoid, of radius, 193
of ulna, 188
of thorax, 558
of tunica vaginalis, 1481
tympanic, 1160
of uterus, 1503
Cavum conchse, 1155
Meckelii, 1042
oris proprium, 1204
Cells, amacrine, 820
arboriform, 821
basket, 902
bipolar, 820
body, nerve, 820
centro-aeinar, of Langerhans,
1359
ciliated endymal, 818
of Claudius, 1185
of cord, commissural, 856
horn, dorsal, 856
lateral, 856
ventral, 856
tract, contra-lateral, 855
homo-lateral, 855
of Deiters, 1185
ectal polymorphous, 958
enamel, 1216
endymal, 832
ental polymorphous, 959
ethmoidal, 82, 100
posterior, 145
ganglion, 820
germinal, 818
giant, 959
IXDKX
Cells, glia-, 832
of Golgi, 821, 902
gustatory, 1101
of Hensen, 1185
hepatic, 1338
horizontal, of Cajal, 1135
of Marti not ti, 960
mastoid, 86
mitral, 960
molecular, 958
multipolar, 820
nerve, 820
axone of, 823
dcndrites of, 822
olfactory, 1111
oxyntic, 1285
parietal, 1285
peptic, of glands, 1285
prickle, 1119
Purkinjean, 902
pyramidal, 958
of Sertoli, 1483
sphenoidal, 94
stellate, 821
unipolar, 820
Cementum of teeth, 1214
development of, 1216
Central canal of cord, 845
coil of cochlea, 1177
fissure, 926
ganglionic system of arteries,
632
lobe of cerebrum, 933
pathway, 964 .
sulcus of Rolando, 926
tendon of diaphragm, 431
Centrifugal nerves, 827
Centripetal nerves, 827
fibre, 823
neurones, peripheral nerve be-
ginnings of, 828
Centro-acinar cells of Langer-
hans, 1359
Centrum medianum, 914
vertebra, 48
Cephalic flexure of brain, 869
index of skull, 147
vein, 747
median, 746
Cephalo-auricular angle, 1154
Cerato-hyals of hyoid bone, 155
Cerebellar arteries, anterior in-
ferior, 642
posterior inferior, 641
superior, 642
cortex, microscopic appear-
ance of, 902
peduncle, 900
prepeduncles, 888
tract of cord, direct, 852
veins, deep, 736
superficial, 736
Cerebello-olivary fibres, 886
Cerebello-spinal tract of cord, 853
Cerebellum, 895
amygdala of, 871, 954
dentatum of, 900
hilum of, 900
embolus of, 900
falcula of, 895
fastigium of, 879, 900
fibres of, 902
association, 902
clinging, 903
commissural, 902
moss, 902
proper, 902
tendril, 903
fissures of, 896
folia of, 895
fra-nulum of, 902
99
Cerebellum, glohulus of, 900
gray masses of, 899
hemispheres of, 896
internal structure of, 899
lobes of, 896
nuclei of, 899
peduncles of, 900
postraimis of, 899
prepeduncles of, 909
preramus of, 899
vallecula of, 895
valvula of, 895
velum of, 895
vermis of, 895
weight of, 903
worm of, 895
Cerebral artery, anterior, 628
branches of, 628
middle, 629
branches of, 629
posterior, 642
convolutions, 922. See Gyre.
cortex, 939
nerve cells of, 958
fibres of, 959
structure of internal, 958
cranium, 71
fibre system, 961
fissures, 922, 923
gyres, 922
hemispheres, 919
configuration of, 922
external morphology of, 919
gray masses of, 952
internal configuration of,
938
hemorrhage, arteries of, 630
lobes, 923
localization, 926
lymphatic vessels, 778
nerves, 1036
portion of internal carotid
artery, 623
veins, 734
cortical, 735
deep, 735
inferior, 735
median, 735
superficial, 735
superior, 735
Cerebro-spinal axis, 833
fasciculus, lateral, 853
fluid, 859
Cerebrum. See Cerebral.
Ceruminous glands, 1159
Cervical artery, ascending, 643
deep, 647
superficial, 644
transverse, 644
canal, 1503
cardiac nerves, 1072
enlargement of spinal cord, 836
fascia, deep, 389
superficial, 388
surgical anatomy of, 391
flexure of brain, 869
ganglion, inferior, 1086
branches, central commu-
nicating, 1086
peripheral, 1086
middle, 1085
branches of, central com-
municating, 1086
peripheral, 1086
superior, 1081
branches of, 1083
central communicating,
1083
peripheral, 1083
surgical anatomy of, 1087
glands, deep, 785
Cervical glands, deep, accessory
chains to, 785
lower, 785
upper, 785
superficial, 783
anterior, 784
nerves, 986
divisions of, anterior, 988
dorsal, 986
from facial nerve, 1063
eighth, division of, dorsal,
987
ventral, 989
fifth, division of. dorsal, 987
ventral, 989
first, division of, dorsal, 986
ventral, 988
root of, dorsal, 986
fourth, division of, dorsal,
987
ventral, 988
posterior, 986
ventral, 988
roots of, 986
second, division of, dorsal,
986
ventral, 988
trunk of, 986
seventh, division of, dorsal,
987
ventral, 989
sixth, division of, dorsal, 987
ventral, 989
superficial, 990
third, division of, dorsal, 987
ventral, 988
pleura, 1393
plexus, 989
branches of, deep, 992
superficial, 989
posterior, 987
surgical anatomy of, 994
portion of internal carotid
artery, 621
of oesophagus, 1236
region, superficial muscles of,
388
rib, 53, 167
veins, anterior deep, 733
posterior deep, 733
vertebra^, 49
lamina* of, 49
body of, 49
pedicles of, 49
processes of, 50
seventh, 53
Cervicalis ascendens muscle, 421
Cervico-facial nerve, 1063
Cervix of bladder, 1444
uteri, 1500
cavity of, 1503
Chassaignac's tubercle, 69
Check ligaments, 280
of eve, 1115
Cheeks, 1205
mucous membrane of, 1205
surgical anatomy of, 1234
Chemical composition of bone, 41
Chest, 156
articulations of, 161
attachment of muscles to, 161
boundaries of, 156
development of, 159
structure of, 159
surface form of, 166
surgical anatomy of, 167"
Chiasm, 919, 1038
Chiasma or optic commissure,
1038
Chink of glottis, 1377
Choamc, 146
1570
INDEX
Chondro-glossus muscle, 399
Chondro-sternal ligament, ante-
rior, 290
interarticular, 290
posterior, 290
Chondro-xiphoid ligament, ante-
rior, 290
posterior, 290
Chondroblasts, 262
Chorda tympani nerve, 1061
Chordae .tendinese of left ven-
tricle, 575
of right ventricle, 572
Willisi, 737
Choroid arteries, anterior, 630
posterior, 642
coat of eye, 1121
structure of, 1122
fissure, 946
nerves of, 1130
plexus. See also Paraplexus.
of fourth ventricle, 881
of lateral ventricle, 943
of third ventricle, 947
vein, 735
Chromatophile granules, 822
Chyli receptaculum, 775
Cilia, or ej'elashes, 1148
Ciliary arteries, anterior, 627
long, 627
short, 627
body, 1125
ganglion, 1040
long root of, 1045
glands, 1200
ligament, 1126
margin, 1127
muscles, 1125
nerves, long, 1045
short, 1045
processes of eye, 1125
structure of, 1125
Ciliated endymal cells, 818
Cimbia, 906
Cingulum, 962
Circle of Willis, 631, 642
Circular sinus, 742
Circulus, 642
of iris, 627
tonsillaris, 1050
Circumanal glands, 1200
Circumduction, 276
Circumflex arteries of arm, 653
of thigh, 705
iliac artery, deep, 698
superficial, 704
vein, deep, 759
superficial, 756
nerve, 1002
lower branch, 1002
upper branch, 1002
vein, deep, 758
Circumflexus muscle, 406
Circuminsular fissure, 925
Circumpatellar anastomosis, 710
Circumvallate papillae of tongue,
1099
Cistern of Pecquet, 775
Cisterna basalis, 977, 978
crural, 978
pontis, 978
Clado, appendiculo-ovarian liga-
ment of, 1312
Clarke, vesicular column of, 844,
847
Claudius, cells of, 1185
Claustrum, 954
gray substance of, 961
Clavi-pectoral fascia, 469
Clavicle, 169
articulations of, 172
Clavicle, attachment of muscles
to, 172
development of, 172
peculiarities of, in sexes anc
individuals, 171
structure of, 171
surface form of, 172
surgical anatomy of, 172
Clavicular facet, 157
Cleft, intercerebral, 921
sylvian, development of, 925
Clinoid process, anterior, 131
middle, 93, 132
posterior, 93, 132
Clitoris, 1493
arteries of, 1494
body of, 1493
. fraenum of, 1494
muscles of, 463
nerves of, 1494
dorsal, 1030, 1495
prepuce of, 1494
Clival lobe of cerebellum, 898
Clivus, 93
Cloquet, canal of, 1139
gland of, 794, 795
ligament of, 1476, 1477
septum crurale of, 511
Coccygeal artery, 694
body, 1417
gland, 1417
ligament, 857
nerve, divisions of, dorsal, 1025
ventral, 1025
plexus, 1034
Coccygeus muscle, 457
Coccyx, 65
apex of, 66
articulation of, 67
attachment of muscles to, 67
base of, 66
borders of, 66
cornua of, 66
development of, 66
surfaces of, 66
Cochlea, 1175
canal of, bony, 1177
membranous, 1182
spiral, 1177
lamina spiralis of, 1177
ligament of, spiral, 1182
Cochlear artery, 1186
nerve, 1064,* 11 86
nuclei of, 892
window, 1162
Coaliac artery, 673
axis, 673
glands, 798
plexus, 1072, 1094
Colic area of kidnevs, 1422
artery, left, 680
middle, 678
right, 677
glands, 806
impression of liver, 1337
plexus, 1094
Collar bone, 169
Collateral, 823
eminence, 944
fissure, 932
intercostal artery, 670
Colles' fascia, 458, 1527
ligament, 439
Colloid material, 1412
Colon, 1317
ascending, 1317
descending, 1317
pelvic, 1317
sigmoid, 1317
surgical anatomy of, 1334
transverse, 1317
Colostrum corpuscles, 1519
Columella cochleae, 1176
Columna nasi, 1106
Columnas carnese of left ventricle,
575
of right ventricle, 572
Columns of Berlin, 1424
of Burdach, 840
of Goll, 839, 840
of Morgagni, 1326
of spinal cord, 839
Clarke's, 844, 847
dorsal, 839
dorso-lateral, 839, 840
dorso-median, 839
lateral, 840
ventral, 840
of vagina, 1496
Comes^nervi ischiadici artery, 694
mediana artery, 665
phrenici artery, 646
Comma tract of Schultze, 851
Commissura hippocampi, 896
ventralis alba, 844
Commissural cells of cord, 856
nerve fibres, 963
of cerebellum, 902
Commissure of cord, gray, 844
white, ventral, 854
Gudden's, 905, 1038
habenal, 915
hippocampal, 951
of Kolliker, 919
of Meynert, 919
optic,"l31, 1038
Common carotid artery, 598
facial vein, 726
femoral artery, 700
iliac arteries, 683
glands, 796
vein, 764
temporal vein, 727
ulnar vein, 745
Communicantes hvpoglossi nerve,
988
Communicating arteries, anterior
cerebral, 629
posterior cerebral, 630
of ulnar, anterior, 664
Compact bone, 35
longitudinal section of, 39
transverse section of, 38
Complexus muscle, 422
Compressor narium minor mus-
cle, 378
sacculi laryngis, 1381
urethras muscle in female, 464
in male, 462
Concentric lines of Schreger, 1213
Concha auriculas, 1155
Condyles of bones. See Bones.
Condylic portion of occipital
bone, 71
Condyloid articulation, 267
foramen, anterior, 73, 133, 136
posterior, 73, 133, 136
fossa, anterior, 136
posterior, 136
glands of Leaf, 794
process, 125
Cone-bipolars, 1135
Cone-granules of retina, 1136
Cones of retina, 1136
Congenital hernia, 1535
Conglobate glands, 774
Conical papillae, 1100
Conjugate diameter of pelvis, 210
Conjunctiva, 1150
bulbar portion of, 1150
fornix of, 1150
glands of, 1150
INDEX
1571
Conjunctiva, nerves of, 1150
palpebral portion of, 1150
surgical anatomy of, 1154
Connective tissue, subserous
1256
Conoid ligament, 302
tubercle, 169
Constriction lobe of liver, 1343
Constrictor isthrni fkucium mus-
cle, 400, 407
muscles, inferior, 402
middle, 403
superior, 403
urethrae muscle in female, 464
in male, 462
Contra-lateral tract-cells of cord
855
Conus arteriosus, 571
of spinal cord, 837
Convolutions. See Gyre.
Cooper, ligament of, 439, 450
Copula, 920
Coraco-acromial ligament, 303
Coraco-brachialis muscle, 477
bursa of, 477
Coraco-clavicular ligament, 302
Coraco-humeral ligament, 306
Coracoid ligament, 304
process, 176
Cord, gangliated, 1081
cervical portion of, 1081
lumbar portion of, 1081
pelvic portion of, 1089
sacral portion of, 1089
thoracic portion of, 1087
spermatic, 1476
spinal, 834. See Spinal cord,
vocal, 1378
Cordiform tendon of diaphragm,
431
Corium, 1190
corpus papillare of, 1191
of tongue, 1099
Cornea, 1118
arteries of, 1121
nerves of, 1121
structure of, 1119
Corneal endothelium, 1121
spaces, 1120
Comical tubercle of Santorini,
1376
Cornicula laryngis, 1373
Cornu ammonis, 937
bulb of, 946
Cornua of coccyx, 66
of hyoid bone, 155
sacral, 62
Corona ciliaris, 1125
glandis, 1464
radiata, 914, 955
Coronal suture, 78, 127
Coronary artery, 673
of heart, 592
descending, 592
infundibular, 593
marginal, 592
peculiarities of, 593
transverse, 592
of lip, inferior, 609
superior, 609
of stomach, 673
ligament of knee, 342
of liver, 1341
plexus, 1094
anterior, 1090
left, 1090
posterior, 1090
right, 1090
sinus, 569, 771
valve, 569
vein, 768
Coronary vein, left, 770
small, 771
Con moid fossa, 183
process of jaw, 125
of ulna, 188
Corpora Arantii, 575
cavernosa, 1465, 1466
arteries of, 1468
bulb of, 1466
structure of, 1467
trabeculae of, 1467
veins of, 1468
quadrigemina, 905. See Quad
rigemina.
Corpus Arantii, 573
callosum, 939. SecCallosum.
cavernosum, artery of, 692
hypothalamicus, 915
papillare of corium, 1191
spongiosum, 1468
structure of, 1469
striatum, 952
Corpuscles, articular, 830
bulboid, 830
epithelial, of Kohn, 1412
genital, 830
of Herbst, 830
lamellated, 830
Malpighian, of kidney, 1426
of spleen, 1365
Pacinian, 830
tactile, 826, 830
touch, 830
of Vater, 830
Corrugator cutis ani muscle, 451
supercilii muscle, 373
Cortex, 939
of brain, 871
cerebellar, microscopic appear-
ance of, 902
cerebral, cells of, 958
nerve fibres of, 959
structure of, internal, 958
Corti, membrane of, 1185
organ of, 1183
rods of, 1184
tunnel of, 1184
Cortical arterial system, 632
cerebral veins, 735
localization of function of
brain, 966
portion of kidney, 1424
of suprarenal capsule, 1439
of thymus gland, 1415
substance of teeth, 1214
Cortico-thalamic fibres, 914
Coruna, horns of, dorsal, 844
lateral, 844
ventral, 844
Costal cartilages, 165
attachment of muscles to,
166
borders of, 166
extremities of, 166
surfaces of, 165
facet, 170
pleura, 1393
process, 50
surface of lungs, 1400
Costo-axillary vein, 748
Costo-central articulations, 285
Costo-chondral articulations, 292
Costo-clavicular ligament, 300
Costo-coracoid ligament, 469
membrane, 469
Costo-mediastinal sinus, 1395
Costo-sternal articulations, 289
Costo-transverse articulations,
287
foramen, 50
ligament, long, 287
Costo-transverse ligament, mid-
dle, 288
posterior, 288
Costo-vertebral articulations, 285
ligament, anterior, 286
Costo-xiphoid ligament, anterior,
290
posterior, 290
Cotunnis, nerve of, 1050
Cotyloid cavity, 220
ligament, 331
notch, 220
Cowper's glands, 1463
structure of, 1463
Cranial bones, 71
fossa, 143
nerves, 1036
arising in mid-brain, deep
origin of, 910
region, dissection of, 368
fascia of, superficial, 368
lymphatics of, 778
vessels of, 781
sutures, 127
Cranio-cerebral topography, 970
Cranio-pharyngeal canal, 917
Cranium, 71
capacity of, 147
cerebral, 71
development of, 102
differences in size and form of,
146
fasciae of, 367
lymphatics of, 778
membranous, 102
muscles of, 367
shape of, 146
Cremaster muscle, 441, 1528
Cremasteric artery, 697
fascia, 1474, 1528
Crescentic lobe of cerebellum,
anterior, 897
posterior, 898
Crescents of Gianuzzi, 1228
Crest, buccinator, 124
ethmoidal, 94
falciform, 89
frontal, 80, 130
incisor, 111
infratemporal, 95
lachrymal, 113
bone, 141
nasal, 111, 116
obturator, 220
occipital, external, 72, 136
internal, 74, 133
sphenoidal, 94
supramastoid, 84, 137
temporal, 76, 80, 84
of tibia, 237
turbinated, inferior, 107, 117
superior, 117
Cribriform fascia, 514, 1539
lamina, 1118
plate, 130
of ethmoid, 99
Crico-arytenoid articulation, 1375
ligaments, 1375
muscle, lateral, 1381
posterior, 1380
Crico-thyroid artery, 605
articulation, 1375
membrane, 1375
muscle, 1380
Crico-tracheal ligament, 1376
Cricoid cartilage, 1371
borders of, 1372
surfaces of, 1372
Crista falciformis, 89
galli, 99, 130
terminalis, 567
1572
INDEX
Crista vestibuli, 1174
Crucial ligaments of knee, 339
Cruciform ligament, 277
Crura, 869
cerebri, 904, 905
pes of, 905, 910
of diaphragm, 429
fornicis, 951
of penis, 1454
Crural arch, deep, 450, 1543
superficial, 438, 1541
canal, 511, 1543
cisterna, 978
nerve. See Femoral nerve,
ring, 439, 511, 1544
septum, 1544
sheath, 511
Crureus muscle, 520
nerve to, 1022
Crus of helix, 1155
Crusta, 910
petrosa of teeth, 1214
Cruveilhier, atlanto-odontoid
joint of, 276
glenoid ligament of, 361
Crypts of Lieberkiihn, 1303
of Morgagni, 1326
Crystalline lens, 1140
capsule of, 1140
substance of, 1140
structure of, 1141
Cuboid bone, 248
articulations of, 248
attachment of muscles to,
248
surfaces of, 248
tuberosity of, 248
Culminal lobe of cerebellum, 897
Cuneal fissure, 931
Cuneate nucleus, accessory, 884
tubercle, 876
Cuneiform bone, foot, 249
external, 251
articulations of, 251
attachment of muscles
to, 251
surfaces of, 251
internal, 249
articulations of, 250
attachment of muscles
to, 250
surfaces of, 250
middle, 250
articulations of, 251
attachment of muscles
to, 251
surfaces of, 250
of hand, 199
articulations of, 199
surfaces of, 199
cartilages, 1373
tubercle of Wrisberg, 1376
Cupola of cochlea, J177, 1182
Cushion of epiglottis, 1373
Cusps of bicuspid valve, 574
of tricuspid valve, 572
Cutaneous nerve, external, 1002,
1018
first ventral, 1011
internal, 1003, 1021
. lateral, 1018
middle, 1021
palmar, 1004
perforating, 1028
Cuticle of skin, 1191
Cutis vera, 1190
Cuvier, duct of, 563
Cylindro-dendrites, 823
Cymba conchsfe, 1155
Cystic artery, 676
duct, 1351
Cystic plexus of nerves, 1094
vein, 769
Czermak, interglobular spaces of
1212
DACRYON, 141, 150
Dartos of scrotum, 1473
Darwin, tubercle of, 1155
Deciduous teeth, 1206
Decussatio nervorum trochlea-
rium, 1041
Decussation of lemnisci, 882
of pyramids, 875, 881
Deep anterior thoracic nerve
1001
branches of cervical plexus
992, 993
cardiac plexus, 1090
cerebral veins, 735
cervical artery, 647
fascia, 389 '
glands, 785
circumflex iliac artery, 698
vein, 759
crural arch, 450, 1543
dorsal vein of penis, 762
epigastric artery, 697
vein, 759
external pudic artery, 704
fascia, 367
of arm, 472, 476
of back, 413
of femoral region, anterior,
515
of forearm, 480
of leg, 535
transverse, 540
of shoulder, 472
of thoracic region, anterior,
465
femoral artery, 704
lymphatic glands, 794
inguinal lymphatic glands, 794
lymphatic glands of upper ex-
tremity, 787
vessels of abdominal wall,
799
of lower extremity, 795
of upper extremity, 790
muscles of abdomen, 451
palmar arch, 660
fascia, 495
veins, 747
parotid lymphatic glands, 780
patellar bursa, 521
pectoral fascia, 466
perineal fascia, 1550
petrosal nerve, 1083
radial veins, 747
superficial external pudic ar-
tery, 704
temporal artery, 616
nerves, 1051
veins, 727
ulnar veins, 747
veins of foot, 758
of lower extremity, 758
of upper extremity, 747
Deiters, cells of, 1185
nucleus of, 853
process, 820
Deltoid eminence, 181
impression, 181
muscle, 472
tubercle, 169
Demilunes of Heidenhain, 1228
De'mours, membrane of, 1120
Dendraxones, 823
Den'drites, 816, 820, 822
Dendrites, monopolar, 821
Dental artery, inferior, 616
posterior, 617
band, 1215
canal, 1212
anterior, 107
inferior, 124
posterior, 106
fibres, 1212
follicle, 1216
lamina, 1215
nerves, anterior superior, 1048
inferior, 1053
middle superior, 1047
posterior superior, 1047
periosteum, 1214
plexus, superior, 1048
pulp, 1210
sac, 1216
Dentate gyre, 938
gray substance of, 960
ligament, 860
nucleus of cerebellum, 900
Dentato-fascicolar groove, 937
Dentatum of cerebellum, 900
hilum of, 900
Dentinal sheath of Neumann^
1213
tubuli, 1212
Dentine, 1212
formation of, 1217
papilla, 1215
Depression, pterygoid, 125
trigeminal, 88
Depressions of bone, 34
Depressor alae nasi muscle, 378
anguli oris muscle, 380
labii inferioris muscle, 380
Dermic coat of hair-follicle, 1198
Dermis, 1190
Descemet, membrane of, 1120
Descendens hvpoglossi nerve,
988
Descending aorta, 667
branch of superior cervical
ganglion, 1084
colon, 1317
mesocolon, 1268
oblique muscle of abdomen,
435
palatine artery, 617
projection nerve fibres, 963
ramus of ischium, 218
of pubis, 220
root of fifth nerve, 1042
Descen^ of ovary, 1513
of testicles, 1471
surgical anatomy of, 1472
Detrusor urina? muscle, 1446
Development of alimentary ca-
nal, 1247
of alveoli of teeth, 1217
of atlas, 59
of axis, 59
of brain, 863
of callosum, 941
of carpal bones, 207
of cementum, 1217
of clavicle, 172
of coccyx, 66
of cranium, 102
of dentine, 1217
of enamel, 1216
of ethmoid bone, 101
of femur, 231
of fibula, 241
of foot, 255
of frontal bone, 82
of humerus, 184
of hyoid bone, 156
of inferior turbinated bone, 120
INDEX
1573
Development of lachrymal bone,
113
of liver, 1253
of maxillary bone, inferior,
125
superior, 112
of mesentery, 1 248
of metacarpal bones, 207
of metatarsal bones, 255
of nasal bones, 105
of nerve tissue, 818
of occipital bone, 75
of omentum, 1250
of organs, chronological table
of, 1559
of os innominatum, 221
of palate bone, 119
of pancreas, 1254
of parietal bone, 78
of patella, 234
of peritoneal cavity, 1253
of peritoneum, 1254
of permanent teeth, 1218
of phalanges of foot, 256
of hand, 208
of radius, 194
of ribs, 165
of sacrum, 64
of scapula, 177
of sphenoid bone, 97
of spinal cord, 840
of spleen, 1255
of sternum, 159
of tarsal bones, 255
of teeth, 1214
of temporal bone, 91
of tibia, 238
of tongue, 1253
of tonsils, 1253
of ulna, 191
of vertebra?, 58
of viscera, 1245
of vomer, 122
Wormian bone, 104
Diagonal fissure, 928
Diameter of pelvis, 210
Diaphragm, 429
actions of, 432
crura of, 429
lymphatics of, 808
nerves of, 432
openings of, 431
aortic, 431
cesophageal, 432
for vena cava, 432
of pelvis, 1241
pillars of, 429
serous membranes of, 432
tendons of, central, 431
Diaphragma sellse, 976
Diaphragmatic ganglion, 1092
hernia, 429
lymphatics, 808
pleura, 1394
portion of ccsophagus, 1236
Diaphysis, 34
Diaplexus, 946
Diarthrosis, 267
Diatela, 912
Diaxonic cells, 823
neurones, 823
Diencephalon, 911
Digastric branch of facial nerve,
1062
f6ssa, 86, 123, 136
muscle, 396
Digestion, organs of , 1203
Digital arteries, dorsal, 661
of ulna, 666
fossa, 225
nerves of foot, 1032
Digital nerves of hand, 1005
Digitations, hippocampal, 947
Dilator naris anterior muscle, 378
posterior muscle, 378
tuba? muscle of Rudinger, 1 1 65
Dimensions of skull, 147
Diploe, 34
veins of, 733
Diploic canals, 733
veins, frontal, 734
occipital, 734
parietal, external, 734
temporal, anterior, 734
posterior, 734
Direct inguinal hernia, 1535
Disk, interpubic, 298
intervertebral, 272
optic, 1131
Dissection of axilla, 465
of cord, 856
of internal oblique muscle, 439
of meninges of brain, 972
of muscles of abdomen, 434
of arm, 471, 476
of auricular region, 371
of back, 412, 416, 417, 419
of cranial region, 368
of femoral region, anterior,
514
internal, 522
posterior, 532
of fibular region, 542
of forearm, 480, 484
of gluteal region, 525
of hand, 493
of iliac region, 510
of infra-hyoid region, 393
of intermaxillary region, 381
' of lingual region, 399
of mandibular region, 380
of orbital region, 374
of palatal region, 405
of palpebral region, 372
of pectoral region, 465
of pharyngeal region, 402
of plantar region, 547, 548,
549
of pterygo-mandibular re-
gion, 386
of radial region, 486
of scapular region, anterior,
473
posterior, 474
of shoulder, 471
of superficial cervical region,
388
of supra-hyoid region, 396
of tibio-fibular region, ante-
rior, 535
posterior, 537, 540
of pancreas, 1355
of perinamm, 1547
of popliteal space, 707
of rectus abdominis muscle, 444
of sole of foot, 545
of temporal muscle, 384
of transversalis muscle, 443
Diverticulum, Meckel's, 1290
Dolichocephalic skull, 146
Dorsal accessory olivary nuclei,
885
area of oblongata, 876
artery of penis, 693
cervical plexus of nerves, 984
columns of spinal cord, 839
coronary plexus, 1090
digital arteries, 661
veins, 745
divisions of cervical nerves,
986
of coccygeal nerve, 1025
Dorsal divisions of lumbar
nerves, 1015
branches, lateral, 1015
medial, 1015
of sacral nerves, 1023
lower, 1023
upper, 1023
branches, lateral,
1023
medial, 1023
of thoracic nerves, 1010
branches, cutaneous,
1010
lateral, 1010
medial, 1010
fissure of oblongata, 875
horn of cornua, 844
horn-cells of cord, 856
interosseous arteries, 661, 715
nerve, 1008
lamina of brain, 870
nerves, 1010
of clitoris, 1030
of penis, 1030
roots of, 1010
pulmonary nerves, 1072
plexus, 1070, 1072, 1091
region, muscles of, 546
root of spinal cord, 836
nerves, 983
sacral plexus of nerves, 984
spinal artery, 641
ulnar vein, 745
veins of penis, deep, 762
superficial, 762
vertebra?, 53. See Thoracic.
Dorsalis hallucis artery, 715
indicis artery, 661
linguae artery, 606
nasi artery, 626
pedis artery, 713
branches of, 714
peculiarities of, 713
relations of, 713
surface marking of, 714
surgical anatomy of, 714
pollicis arteries, 661
scapula? artery, 653
Dorsi-lumbar nerve, 1016
Dorsi-spinal veins, 753
Dorso-lateral columns of spinal
cord, 839, 840
fissure of oblongata, 875
of spinal cord, 839
Dorso-median columns of spinal
cord, 839
fissure of oblongata, 875
veins, 736
Dorso-paramedian fissure of
spinal cord, 839
Dorso-spino-cerebellar tract of
cord, 852
Dorsum ephippii, 93, 132
of penis, 1465
of scapula, 173
sellse, 93
Douglas, fold of, semilunar, 441,
446
pouch of, 1502
Drumhead, 1165
Duct or ducts, alveolar, 1386
of Bartholin, 1227
biliary, 1348
of Cuvier, 563
cystic, 1351
efferent of epididymis, 1482
ejaculatory, 1487
galactophorus, 1518
Gartner's, 1511
hepatic, 1350
interlobular. 1349
1574
INDEX
Duct or ducts of kidney, 1429
lactiferous, 1518
of liver, 1348
lymphatic, right, 777
mammillary, 1518
nasal, 1152
pancreatic, 1359
parotid, 1225
of Rivinus, 1227
seminal, 1484
Stenson's, 1225
of submaxillary gland, 1226
thoracic, 775
thyroglossal, 1100, 1407
Wharton's, 1226
Ductless glands, 1407
Ductus arteriosus, 582
communis choledochus, 1351
endolymphaticus, 89, 1175
venosus, fissure of, 1338
fossa of, 1339
Duodenal area of kidney, 1422
folds, 1270
fossae, 1270
glands, 1303
impression of liver, 1337
Duodeiio-jejunal fossa, 1271
Duodeno-mesocolic ligaments
1271
Duodeno-renal ligament, 1264
Duodenum, 1290
arteries of, 1296
ascending portion of, 1294
descending portion of, 1293
first portion of, 1292
flexure of, superior, 1293
fourth portion of, 1294
horizontal portion of, 1293
interior of, 1296
lymphatics of, 1296
muscular coat of, 1296
nerves of, 1296
peritoneal coat of, 1296
pre-aortic portion of, 1293
second portion of, 1293
structure of, 1296
submucous coat of, 1296
superior portion of, 1292
surgical anatomy of, 1332
suspensory muscle of, 1294
third portion of, 1293
transverse portion of, 1293
veins of, 1296
Dura of brain, 972
arteries of, 974
lymphatics of, 974
nerves of, 974
processes of, 975
structure of, 972
veins of, 974
mater of brain, 972
of cord, 856
sinuses of, 736
spinal, 856
structure of, 858
Dural artery, 611, 612
nerves, 1046
veins, 730, 734
Duverney, gland of, 1495
EAR, 1154
auditory meatus, external,
1158
auricle of, 1154
bones of, 1168
cartilages of, 1156
cochlea, 1175
external, 1154
Ear, external, auricle of, 1154
lobule of, 1155
internal, 1173
labyrinth, 1173
membranous, 1179
osseous, 1174
middle, 1160
muscles of auricle, 1157
of tympanum, 1171
ossicula of, 1168
pinna of, 1154
semicircular canals of, 1175
surgical anatomy of, 1186
trumpet, 1163
tympanum, 1160
Ear-drum membrane, secondary
1162
Ebner, von, glands of, 1101
Ectal arcuate fibres of postob
longata, 886
polymorphous nerve cells, 958
Efferent nerve, 827
root of spinal cord, 836
Egg tubes, 1515
Eighth nerve, 1064
surgical anatomy of, 1065
Ejaculator seminis muscle, 459
urinaj muscle, 459
Ejaculatory ducts, 1487
Elastic cartilage, 262
tissue, yellow, 264
Elbow, bend of, surgical anatomy
of, 655
bone, 186
bursa of, 313
ligament of, anterior, 311
posterior, 311
Elbow-joint, articulations of, 310
surface form of, 314
surgical anatomy of, 314
Eleventh nerve, 1073
surgical anatomy of, 1074
thoracic vertebra, 56
Ellipsoid of Krause, 1137
Elliptical recess, 1174
Embolus of cerebellum, 900
Eminence, articular, of temporal
bone, 84
of bone, 34
canine, 106
deltoid, 181
frontal, 79
ilio-pectineal, 217, 220
of Jacobson, 1110
nasal, 79
olivary, 93
parietal, 76
Eminentia abduceritis, 880
articularis, 84, 135
concha?, 1156
fossa? triangularis, 1156
Emissary veins, 743
surgical anatomy of, 743
Emulgent vein, 766
Enamel cells, 1216
cuticle, 1214
fibres, 1213
jelly, 1216
prisms, 1213
of teeth, 1213
development of, 1216
Enamel-organ of tooth, 1215
Enarthrosis, 268
Encephalon, 860
Encysted hernia, 1535
End-bulb of Krause, 826, 830
Endocardium, 576
Endo-exo-gnathion suture, 111
Endo-gnathion suture, 111
Endolymph, 1179
Endo-meso-gnathion suture, 111
Endomysium, 364
Endoneurium, 826
Endosteum, 36
Endothelium, corneal, 1121
Endothoracic fascia, 1393
End-plates, motor, 828
Endyma, 881
Endymal cells, 832
ciliated, 818
Ensiform appendix, 159
surfaces of, 159
cartilage, 156
Ental arcuate fibres of postob-
longata, 886
polymorphous nerve-cells, 959
Eosinophiles, 36
Epactal bones, 103
Eparterial branch of bronchus,.
1385
Epencephalon, 860
Epicardium, 576
Epicondyles, 182
Epicondylic ridge, 181
Epicteric bone, 103
Epidermic coat of hair-follicle,
1198
Epididymis, 1480
structure of, 1482
Epidural space, 857, 973
Epigastric artery, deep, 697
peculiarities of, 697
surgical anatomy of, 698
internal, 697
superficial, 704
superior, 647
glands, superior, 800
plexus, 1091
vein, deep, 759
Epiglottis, 1373
cartilage of, 1373
cushion of, 1373
surfaces of, 1373
Epimysium, 364
Epineurium, 826
Epiotic portion of temporal boner
91
Epiphyseal cartilage, 36, 867, 915
recess, 915
Epiphysis, 867, 915
albicantia of, 916
of bone, 34
postcommissure of, 915
postperi'oration of, 916
structure of, 915
Episylviari ramus, 925
Epithalamus, 916
Epithelial corpuscles of Kohn,.
1412
Epithelium. See Various organs,
germinal, of Waldeyer, 1513
lens, 1140
transitional, 1437
Epitrochlea, 183
Epitympanic recess, 87, 1160
space, 87
Epo-ophoron, 1511
Erectile tissue of penis, 1467
of vagina, 1497
Erector clitoridis muscle, 463
penis muscle, 460
spina? muscle, 419
Crythroblasts, 36
Cthmo-frontal suture, 130
Cthmo-sphenoidal suture, 130-
Cthmoid bone, 98
articulations of, 102
cribriform plate of, 99
development of, 101
horizontal lamina of, 99
infundibulum of, 101
lateral mass of, 100
JATZ>/:A
1575
Ethmoid bone, os plammi of. 1(K)
perpendicular plate <>t'. ino
unciform process of, 100
Ethmoidal arteries, 625
canals, 82, 100
cells, 82, 100
posterior, 145
crest, 94
foramina, 82
anterior, 130, 141
posterior, 130, 141
notch, 82
process of inferior turbinated
bone, 120
sinuses, 101
spine, 93, 130
Eustachian cushion, 1231
tube, 1163
canal for, 1164
cartilaginous portion of,
1164
osseous portion of, 1164
valve, 569
in foetus, 581
Excito-glandular neurones, 816
Excito-motor neurones, 816
Excretory apparatus of liver,
1342
Exo-gnathion suture, 111
Expiration, muscles of, 434
Expression, muscles of, 387
Exsanguinated renal zone of
Hyrtl, 680, 1423
Extensor brevis digitorum mus-
cle, 546
pollicis muscle, 491
carpi radialis brevior muscle,
487
bursa of, 488
longior muscle, 487
ulnaris muscle, 489
coccygeus muscle, 424
communis digitorum muscle,
488
indicis muscle, 492
longus digitorum muscle, 536
pollicis muscle, 491
minimi digiti muscle, 489
ossis metacarpi pollicis muscle,
491
primi internodii pollicis mus-
cle, 491
proprius hallucis muscle, 535
secundi internodii pollicis mus-
cle, 491
External abdominal ring, 437,
1526
acoustic canal, 1158
angular process, 80, 140
annular ligament, 545
anterior thoracic nerve, 1001
arcuate ligament, 429, 451
auditory canal, 1158
meatus, 138, 1158
bicipital ridge, 181
calcanean artery, 718
calcaneo-astragaloid ligament ,
354
calcaneo-scaphoid ligament,
355
capsule of brain, 957
carotid artery, 602
foramen, 89
circumflex artery of thigh,
705
condyle of femur, 228
crucial ligament, 339
cutaneous nerve, 1002, 1018
ear, 1154
epicondyle, 182
hiemorrhoidal veins, 760
Kxti-rnal iliac artery, 695
glands, 795
vein, 759
inguinal fossa, 1532
hernia, 1532
interchondral ligament, 292
intercostal muscle, 427
jugular vein, 728
lateral ligament, 2S2, 312
malleolus, 241
ligament of, 1170
mammary artery, 653
maxillary artery, 607
oblique line, 123
muscle, 435
aponeurosis of, 1525
occipital crest, 72, 136
protuberance, 71, 136
orbital foramina, 95
os, 1501
palatine nerve, 1050
palpebral arteries, 625
parietal diploic vein, 734
plantar artery, 719
nerve, 1032
popliteal nerve, 1033
pterygoid muscle, 386
nerve, 1051
plate, 96
pudic artery, deep, 704
superficial, 704
deep, 704
saphenous gland, 794
vein, 756
semicircular canal, 1175
semilunar fibrocartilage, 341
spermatic fascia, 438, 1526
nerve, 1018
sphincter ani muscle, 452
supracondylar ridge, 181
tarsal ligament, 373
tuberosity of tibia, 236
Extracranial lymphatics, 778
Extrinsic muscles of tongue,
400
Eye, 1113
appendages of, 1147
aqueous humor of, 1138
choroid, 1121
ciliary muscle, 1125
conjunctiva, 1150
cornea, 1118
crystalline lens, 1140
globe of, arteries of, 1142
lymphatics of, 1143
nerves of, 1144
veins of, 1143
iris, 1127
lachrymal apparatus, 1151
glands, 1151
sac, 1152
nasal duct, 1152
pupil of, 1127
refracting media of, 1138
retina, 1130
sclera, 1117
surgical anatomy of, 1144
tunics of, 1117
uveaof, 1128
vitreous body of, 1139
Eyeball, coverings of, 377
Eyebrow, 1147
Eyelashes, 1148
Eyelid, 1147
Meibomian glands of, 1149
orbital portion of, 1147
structure of, 1148
surface form of, 1152
surgical anatomy of, 1153
tarsal portion of, 1147
Eye-teeth, 1207
F
FACE, arteries of, 607
bones of, 104
fasciie of, 367
lymphatics of, 778
muscles of, 367
surface form of, 387
nerves of, 1059
veins of, 725
Facet, clavicular, 157
costal, 170
Facial artery, 607
branches of, 608
relations of, 608
surgical anatomy of, 610
transverse, 613
bones, 104
index of skull, 147
nerve, 1059
branches of, 1060
nuclei of, 893
afferent, 894
efferent, 894
surgical anatomy of, 1064
>inus, 738
suture, transverse, 128
vein, anterior, 726
common, 726
surgical anatomy of, 726
transverse, 727
Falciform crest, 89
ligament, 295
of liver, 1340
process of fascia lata,
517
Falcula, 895, 976
Fallopian tube, 1510
ampulla of, 1510
artery of, 1511
course pursued by, 1510
fimbriffl of, 1510
infundibulum of, 1510
isthmus of, 1510
lymphatics of, 801, 1511
nerve of, 1511
structure of, 1510
uterine portion of, 1510
vein of, 151 1
False pelvis, 209
ribs, 161
vocal cords, 1378
Falx, 922, 975
cerebelli, 976
cerebri, 975
inguinalis, 450
Fascia or fasciae, 363
of abdomen, deep, 435
superficial, 435, 1523
triangular, 1527
of acromial region, 472
anal, 456, 1558
of arm, 476
deep, 472, 476
superficial, 472
axillary, 465, 648
of back, deep, 413
superficial, 413
bicipital, 478, 746
bucco-pharyngeal, 383, 390,
403, 1232
of Camper, 435
cervical, deep, 389
superficial, 388
clavi-pectoral, 469
of Colics, 458, 1527
costo-coracoid, 469
of cranial region, 368
of cranium, 367
cremasteric, 1474, 1528
cribriform, 514, 1539
1576
INDEX
Fascia or fasciae, deep, 367
dentate, 938
endo-pelvica, 1556
endothoracic, 1393
of face, 367
of femoral region, anterior
deep, 515
superficial, 514
of foot, 544
of forearm, 480
of hand, 493
of hip, 525
iliac, 510
infraspinatus, 474
infundibuliform, 448, 1475
intercolumnar, 438, 1474, 1526
intercostal, 426
ischio-rectal, 456, 1558
lata, 515, 1539
falciform process of, 1540
iliac portion, 517, 1540
pubic portion, 517, 1540
of leg, 535
transverse, 540
of lower extremity, 509
masseteric, 383
of neck, 387
obturator, 1558
of orbit, 377
palmar, deep, 495
palpebral, 1149
parotid, 389, 1225
parotideo-masseterica, 389
pectoral, deep, 466
pelvic, 1556
of perinteum in male, deep,
460, 1550
superficial, 457
phrenico-pleural, 1395
plantar, 545
pre-tracheal, 391
prevertebral, 390
of quadratus lumborum, 451
recto-vesical, 1558
retro-renal, 1420
salpingopharyngea of Troltsch,
1165
of Scarpa, 435
semilunar, 478
of shoulder, deep, 472
superficial, 472
spermatic, 1474
external, 438, 1526
internal, 448
middle, 442
subseapular, 473
superficial, 366
supraspinatus, 474
temporal, 384
of thigh, 514
of thoracic region, anterior,
deep, 465
superficial, 465
of thorax, 426
transversalis, 447, 1529
triangular, 439
of trunk, 412
of upper extremity, 464
Fascial canal, 1548
Fasciculi, 264
proprii, 849
Fasciculus albicantiothalami, 914
archiformis pedis, 906
longitudinal, inferior, 962
superior, 962
marginalis, 849 .
pedunculomammillaris, 916
perpendicular, 962
rectus, 962
retroflexus, 908
thalamomammillaris, 914, 916
Fasciculus of Tiirck, 854
uncinate, 962
Fasciola, 938
Fastigatum of cerebellum, 900
Fastigium of cerebellum, 879
Fauces, isthmus of, 1222
pillars of, 1221
Female bladder, 1455
organs of generation, 1489
perinaeum, 1554
urethra, 1455
Femoral artery, 698
anastomotica magna of, 706
branches of, 704
common, 700
deep, 704
peculiarities of, 702
superficial, 701
surface marking of, 702
surgical anatomy of, 702
canal, 511, 1543
cutaneous nerves, 1028
hernia, 1537
complete, 1546
coverings of, 1545
descent of, 1545
incomplete, 1545
varieties of, 1545
ligament, 517
lymphatic glands, deep, 794
nerve, 1021
region, anterior, fascia of, deep
515
superficial, 514
surgical anatomy of, 517
muscles of, 514
dissection of, 514
surgical anatomy of,
521
internal, muscles of, 522
dissection of, 522
surgical anatomy of,
525
posterior muscles of, 532
dissection of, 532
surgical anatomy of,
534
ring, 439, 511, 1544
sheath, 511, 1542
spur, 229
vein, 758
Femur, 223
articulations of, 231
attachment of muscles to, 231
condyles of, 227
development of, 231
lower extremity of, 227
shaft of, 226
borders of, 227
linea aspera, 226
surfaces of, 227
spiral line of, 225
structure of, 228
surface form of, 231
surgical anatomy of, 232
trochlea of, 227
tubercle of, 225
tuberosities of, 228
upper extremity of, 223
head of, 223
neck of, 223
trochanters of, 225
Fenestra ovalis, 1162
rotunda, 1162, 1177
Fenestrated membrane of Henle,
587
space, posterior, 859
Ferrein, pyramids of, 1425
Fibre-baskets, 1137
Fibres, arcuate, of postoblongata,
886
Fibres of auricles of heart, 577
cardiac muscular, 363
cerebello-olivary, 886
of cerebellum, association, 902
clinging, 903
commissural, 902
moss, 902
proper, 907
tendril, 903
of cerebral cortex, 959 '
of cord, longitudinal, 848
cortico-thalamic, 914
dental, 1212
enamel, 1213
intercolumnar, 438
lens, 1140
muscle, 363
nerve, association, 961
commissural, 963
projection, 963
thalamo-frontal, 956
thalamo-striate, 956
olivo-cerebellar, 886
of pons, longitudinal, 887
transverse, 887
preanal, of levator ani, 455
pr£-rectales, 456
of Purkinje, 577
of Sharpey, 37
sustentacular, 1131
of tegmentum of mid-brain,
908
thalamo-cortical, 914
of ventricles of heart, 577
Fibre-tracts in pre-oblongata,
888
cere.bellar prepeduncle, 888
lateral lemniscus, 888
medial lemniscus, 888
longitudinal bundle, 888
Fibrils, side, 823
FibrillaD, terminal, 830
Fibro-cartilage, 262
circumferential, 263
connecting, 263
interarticular, 283, 300, 302
triangular, 317
intervertebral, 272
semilunar, 339
stratiform, 263
Fibro-elastic coat of spleen, 1363
Fibro-muscular coat of gall-
bladder, 1351
Fibrous coat of liver, 1345
of pharynx, 1233
of ureter, 1436
layer of pericardium, 560
membrane of trachea, 1387
rings of heart, 576
septum of tongue, 400
sheaths of flexor tendons, 548
tissue, white, 263
Fibula, 239
articulations of, 241
attachment of muscles to, 241
development of, 241
lower extremity of, 241
nutrient artery of, 717
oblique line of, 240
shaft of, 240
styloid process of, 239
surface form of, 241
surgical anatomy of, 244
upper extremity of, 239
Fibular artery, superior, 712
region, muscles of, 542
actions of, 543
dissection of, 542
surgical anatomy of 544
Fifth lumbar vertebra, 57
nerve, 1041
1577
Fifth nerve, scmilunar ganglion
of, 1042
surface marking of, 1055
surgical anatomy of, 1055
ventricle, 920, 921 ', 941
Filiform papilla1 of tongue, 1100
Filtrum ventriculi of Merkel,
1376
Fihini <lur:i> spinalis, 857
externum, 837
intornuin, 837
Fimbria, 937, 938, 945, 950
Firnbriae of Fallopian tube, 1510
of ovary, 1512
Finger, index, metacarpal bone
of, 204
ligaments of, 324
superficial transverse, 496
little, metacarpal bone of, 205
middle, metacarpal bone of,
204
ring, metacarpal bone of, 205
veins of, superficial, 745
First nerve, 1037
thoracic vertebra, 55
Fissura antitragohelicina, 1156
vi-stibuli, 117S
Fissure or fissures, amvgdaline,
932, 933
antitrasiohelioina, 1156
auricular, 90, 136
bivsisylvian, 924
of brain, 922, 923
calcarine, 926
central, 926
of cerebellum, 896
cerebral, 922, 923
choroid, 946
circuminsular, 925
collateral, 932
of cord, 838
cuneal, 931
diagonal, 928
of ductus venosus, 1338
of frontal lobe, 920
of gall-Madder, 1338
dlaserian, 84, 1162
inflected, 928
insular, 933
central, 933
intereerebral, 921
interlobar, 924
intermedial, 931
of liver, 1338
longitudinal, 1338
transverse, 1338
of lung, 1402
mammary, prolongations of,
1518
medifrontal, 927
meditemporal, 932
of oblongata, 874
dorsal, 875
dorso-lateral, 875
dorso-median, 875
ventral, 874
ventro-lateral, 875
ventro-median, 874
occipital, 926
inferior, 931
lateral, 931
lobe, 931
olfactory, 928
orbital, 96
or bi to-frontal, 927
paracentral, 928
paramesal, 927
parietal lobe, 930
paroccipital, 930
petro-tympanic, 84, 1162
portal, "1338
Fissure or fissures, post-calca-
rinc, 926
post-central, 930
precrntral, 927
superior, 927
prccuneal. 931
pterygo-maxillary, 139
pterygoid, 96
radiate, 928
rhinal, 933
rhinica, 933
of Rolando. 926
rostral, 928
spheno-maxillary, 115, 138
sphenoidal, 96, 132
. of Santorini, 1156, 1158
of spinal cord, 838
dorso-lateral, 839
dorso-paramedian, 839
ventro-paramedian, 839
subfrontal, 927
suboccipital, 931
subrostral, 928
subtemporal, 932
supercentral, 927
superfrontal, 927
supertemporal, 932
sylvian, 924
temporal lobe, 931
of tragus, 1156
transinsular, 933
transorbital, 929
transparietal, 931
transprecentral, 928
transtemporal, 932
umbilical, 1338
Flat bones, 34 \
Flechsig, nucleus semilunaris of,
914
oval bundle of, 851
Flexor accessorius muscle, 549
brevis digitorum muscle, 547
hallucis muscle, 549
minimi digiti muscle, foot,
550
hand, 500
pollicis muscle, 499
carp radialis muscle, 481
ulnaris muscle, 482
longus digitorum muscle, 541
hallucis muscle, 541
pollicis muscle, 484
ossis metacarpi pollicis mus-
cle, 498
profundus digitorum muscle,
484
sublimis digitorum muscle, i83
tendons, fibrous sheaths of, 548
Flexure of brain tube, 869
cephalic, 869
cervical, 869
pontile, 869
of colon, hepatic, 1317
sigmoid, 1317
splenic, 1317
of duodenum, superior, 1293
of large intestine, hepatic, 1308
sigmoid, 1308
splenic, 1308
Floating lobe of liver, 1343
Floccular fossa, 89, 133
Hood's ligament, 306
Flower's gnathic index of skull,
148
Fluid, cerebro-spinal, 859
Postal circulation, 583
lung, 1402
Fold of Douglas, semilunar, 441,
446
duodenal, 1270
hypogastric, 1531
Fold, ovario-pelvic, 1512
recto-vaginal, 1502
of urachus, 1531
utero-vesical, 1502
of uterus, 1501
Folia, 895
linguae, 1097
Follicle, dental, 1216
simple, 1303, 1327
Folliculv lymph-sinus, 1314
I'ontana, spaces of, 1120
Fontanelles, 102
anterior, 78, 103
antero-lateral, 103
bregmatic, 103
posterior, 103
postero-lateral, 103
Foot, arteries of, 713
bones of, 244
bursae of, 546
development of, 255
fasciae of, 544
ligaments of, 544
muscles of, 544
nerves of, 1031
phalanges of, 255
articulations of, 361
sole of, dissection of, 545
surface form of, 257, 362
surgical anatomy of, 257, 362
veins of, 758
Foramen, 96
cascum, 80, 130, 874
carotid, external, 89
internal, 88
condyloid, anterior, 73, 133, 136
posterior, 73, 133, 136
costo-transverse, 50
dental, inferior, 124
ethmoidal, anterior, 130, 141
posterior, 130, 141
of Huschke, 92
infraorbital, 106, 140
jugular, 73, 133
of Key and Retzius, 978
lacerum anterius, 96, 132
medium, 132
posterius, 133
of Langer, 466, 648, 790
of Luschka, 978
magnum, 72, 133
of Majendie, 859, 881, 978
malar, 113
mastoid, 85, 138
mental, 123, 140
of Monro, 866, 913
obturator, 220
optic, 93, 131, 142
ovale, 95, 132, 569
in fostus, 581
palatine, great, 116
posterior, 135
parietal, 76
pterygo-palatine, 95
quadratum of diaphragm, 432
rotundum, 95, 132
sacro-sciatic, great, 218, 296
singulare, 89, 1179
of Somm erring, 1131
spheno-palatine, 119, 143
spinal, 49, 132
sternal, 159
stylo-mastoid, 90, 135
supraorbital, 80, 140
supratrochlear, 183
temporo-malar, 115
thyroid, 220
vertebral, 49
vertebrarterial, 50
Vesalii, 95, 132
Foramina of diaphragm, 432
1578
INDEX
Foramina, ethmoidal, 82
incisor, 110
intervertebral, 49
of Key and Retzius, 859
Luschkae, 881
malar, 113
olfactory, 143
orbital, external, 95
sacral, anterior, 62
posterior, 63
of Scarpa, 110, 135, 1050
of Stenson, 1 10
Thebesii, 569, 570, 771
Forearm, arteries of, 659
bones' of, 186
fascia? of, 480
interosseous veins of, 747
lymphatics of, 787
muscles of, 480
dissection of, 480, 484
nerves of, 1000
veins, 744
Fore-brain, 865, 911
epiphysis of, 915
structure of, external, 911
thalami of, 912
third ventricle of, 916
vesicles of, secondary, 866
Fore-chambers of heart, 5C7, 57C
Fore-gut, 1246
Form of bones, 33
Formatio reticularis, 882, 884
910
alba, 884
grisea, 884
Fornicolumns, 951
Fornicommissure, 951
Fornix, 921, 943, 949
body of, 949, 951
of conjunctiva, 1150
periphericus, 962
pillars of, 950
vaginal, 1496
Fossa or fossae of acetabulum,
220
of antihelix, 1154
canine, 106, 140
condyloid, anterior, 136
posterior, 136
coronoid, 183
cranial, 143
digastric, 86, 123, 136
digital, 225
duodenal, 1270
duodeno-jejunal, 1271
floccular, 89, 133
glenoid, 84, 135
of helix, 1154
hypophyseos, 917
ileo-appendicular, 1272
ileo-cracal, 1272
ileo-colic, 1272
iliac, 216
incisive, 106, 123, 139
incudis, 1163
mfraspinous, 174
inguinal, 1258, 1532
intersigmoid, 1319
ischio-rectal, 1548
jugular, 91
lachrymal, 81
of Landzert, 1271
longitudinal, of liver, 1338
mandibular, 84
mastoid, 86
mesocolic, 1271
myrtiform, 106
nasal, 142, 1108
navicularis of urethra, 1453
occipital, 133
olecranori, 183
Fossa or fossa?, orbital, 143
ovalis, 569
palatine, 110, 133
paraduodenal, 1271
patellaris, 1139
pericsecal, 1271
pituitary, 93
pterygoid, 96, 115
radial, 183
retro-csecal, 1272
retro-colic, 1272
retro-duodenal, 1271
retro-peritoneal, 1270
of Rosenmuller, 1231
of Scapha, 1155
scaphoid, 97, 135, 1154
sigmoid, 86
of skull, anterior, 130
infratemporal, 138
middle, 130
orbital, 140
posterior, 132
pterygo-palatine, 139
spheno-maxillary, 139
temporal, 137
zygomatic, 138
spheno-maxillary, 115
sublingual, 123
submaxillary, 123
subscapular, 172
supra-tonsillar, 1223
supraspinous, 174
temporal, 76
of Treitz, 1270
trochanteric, 225
trochlear, 82
umbilical, 1338
Fossula inferior, 1178
superior, 1178
Fountain decussation, 910
Fourchette, 1490
Fourth nerve, 1041
ventricle, 878
choroid plexuses of, 881
floor of, 879
roof of, 881
Fovea centralis retinae, 1131,
1138
hemielliptica, 1174
hemispherica, 1174
inferior, 880
inguinalis lateralis, 1532
mesialis, 1532
mediana, 880
oblonga, 1372
superior, 880
supra-vesicularis, 1532
triangular is, 1372
Foveolse, Howship's, 38
Framulum of cerebellum, 902
Giacomini, 938
of ileo-cfflcal valve, 1316
Fraenum of clitoris, 1494
labii superioris et inferioris,
1204
linguae, 1097
of penis, 1465
Frontal air sinus, 82
artery, 613
from anterior cerebral, ante-
rior internal, 628
inferior internal, 628
middle internal, 629
posterior internal, 629
from middle cerebral, as-
cending, 630
inferior external, 630
from ophthalmic, 625
bone, 79
horizontal portion of, 81
articulations of, 83
Frontal bone, horizontal portion
of, attachment of
muscles to, 83
border of, 82
development of, 82
structure of, 82
orbital portion of, 81
articulations of, 83
attachment of muscles.
to, 83
border of, 82
development of, 82
structure of, 82
vertical portion of, 79
border of, 81
structure of, 81
crest, 80, 130
diploic vein, 734
eminence, 79
lobe, 926
fissures of, 926
gyres of, 929
nerve, 1043
process of malar, 114
spine, 80
suture, 79, 127
vein, 725
Frontalis muscle, 369
Fronto-malar suture, 1 28
Fronto-parietal operculum, 925-
suture, 127
Fronto-pontile tract, 910
Fronto-sphenoidal suture, 128
Fundament of cerebellum1, 869
Fundamental plexus, 1121
Fundiform ligament of Retzius,
544
Furidus glands, 1285
of internal auditory meat us,
1178
tympani, 1161
of uterus, 1499
Fungiform papillae of tongue,
1100
Funicular process, hernia of,,
1535
Fuiiiculus cuneatus, 876
gracilis, 876
lateralis, 876, 884
separans, 879
Furcula, 1253
Furrow, interauricular, 567
sternal, 166
Fusiform muscles, 365
A.LACTOPHORTJS duct, 1518
Galen, testes muliebres of, 1511
veins of, 735, 771
Gall-bladder, 1350
arteries of, 1353
body of, 1350
fibro-muscular coat of, 1351
fissure for, 1338
fundus of, 1350
lymphatics of, 1353
mucous coat of, 1351
neck of, 1350
nerves of, 1353
notch of, 1338
relations of, 1350
serous coat of, 1351
structure of, 1351
surgical anatomy of, 1354
veins of, 1353
anglia, basal, 867, 952
of nerves, 827
spinal, 983
aberrant, 983
INDEX
1579
Ganglia of nerves, spinal, acces-
sory, 983
semilunar, of abdomen, 1091
Gangliated cord, 1081
cervical portion of, 1081
lumbar portion of, 1089
pelvic portion of, 1089
sacral portion of, 1089
thoracic portion of, 1087
Ganglion of Andersch, 1066
Arnold's, 1053
of Bochdalek, 1048
cardiac, of Wrisberg, 1090
carotid, 1083
cell, 820
cervical, inferior, 1086
middle, 1085
superior, 1081
ciliary, 1045
long root of, 1045
diaphragmatic, 1092
of facial nerve, 1059
of fifth nerve, 1045
Gasserian, 1042
geniculate, 1013, 1059
of glossu-pharyngeal, 1066
impar, 1078
inferior, 1086
interpeduncular, 908
jugular, 1086
lenticular, 1040
lumbar, 1089
.Mockers, 1048
mesenteric, 1094
ophthalmic, 1045
otic, 1053
peripheral, 1083
petrous, 1066
pharyngeal, 1070
phrenic-, 1092
of Ribes, 1077
of Scarpa, 1065
semilunar, of abdomen, 1091
of fifth nerve, 1042
spheno-palatine, 1048
of spinal nerves, 983
submaxillary, 1054
superior, 1066
of sympathetic nerves, 1080
thoracic, 1087
thyroid, 1085
of vagus, 1069
of Valentin, 1047
vestibular, 1065
Ganglionic arteries, postero-
lateral, 642
postero-median, 642
branch of nasal nerve, 1045
system of arteries, central, 632
vessels of brain, central, 631
Gartner's duct, 1511-
Gasserian ganglion, 1042
Gastric area of kidney, 1422
artery, 673, 676
glands, 798, 1285
impression, 1340
nerves, 1072
plexus, 1094
surface of liver, 1336
of spleen, 1361
veins, 768
Castro-colic omentum, 1266
Gastro-duodeiial plexus, 1094
Gastro-duodenalis artery, 675
Gastro-epiploic plexus, 1094
left, 1094
vein, 768
Gastro-epiploica dextra artery,
675
sinistra artery, 676
Gastro-hepatic omentum, 1264
( iastro-spleiiif ligament, 1266
omentum, 1266
Gastrocnemiua muscle, 537
bursa of, 537
Gemellus muscle, inferior, 530
superior, 529
Gemmules, S23
Generation, organs of, develop-
ment of, 1559
female, 1489
male, 1457
Genial gland, 781
tubercles, 123
ganglion, 1048, 1059
tract, 956
Genio-glossus muscle, 399
Genio-hyo-glossus muscle, 399
Genio-hyoid muscle, 397
Genital corpuscles, 830
Genito-crural nerve. See Genito-
femoral.
Genito-femoral nerve, 1018
femoral branch, 1018
genital branch, 1018
Gennari, fibre band of, 959
Genu splenium of callosum, 920
Gerlach, valve of, 1310
Germinal cells, 818
epithelium of Waldeyer, 1514
Giant cells, 959
Gianuzzi, crescents of, 1228
Gimbernat's ligament, 439, 1527
Gingival branches of dental
nerves, 1047
Ginglymus, 267
Giraldes, organ of, 1484
Girdle shoulder, 168
Glabella, 150
of frontal bone, 80, 139
Gladiolus, 157
borders of, 159
surfaces of, 159
Glands, absorbent, 774
agmiriated, 1304
apical, 1101
arytenoid, 1385
of Bartholiii, 1495
of biliary ducts, 1349
of Bowman, 1111
bronchial, 1389
Brunner's, 1303
buccal, 1205
cardiac, 1286
carotid, 1416
ceruminous, 1159
ciliary, 1200
circumanal, 1200
coccygeal, 1417
conglobate, 774
Cowper's, 1453
ductless, 1407
duodenal, 1303
of Duverney, 1475
epiglottis, 1382
fundus, 1285
gastric, 1285
infralaryngeal, 785
interbronchial, 1389
intestinal, 1303, 1327
labial, 1204
lachrymal, 1151
of larynx, 1382
lenticular, of stomach, 1285
of Lieberkuhn, 1303, 1327
lingual, 1101
of Littre\ 1453
Luschka's, 1417
lymphatic, 774
mammary, 1516
Meibomian, 1149
molar, 1205
Glands of Moll, 1148
of Montgomery, 1516 «
mucilaginous, 265
mucous, 1228
of Nuhn and Blandin, 110L
odoriferae, 1464
oesoph:igcal, 1239
oxyiitic, 1285
of Pacchioni, 737
palatal, 1221
parathyroid, 1412
parotid, 1224
peptic, 1285
peritracheo-bronchial, 138&
Peyer's, 1304
pharyngeal, 1233
prelaryngeal, 785
prostate, 1457
pyloric, 1285
of Rosenmuller, accessory,
1151
salivary, 1224
sebaceous, 1148, 1201
solitary, 1303, 1327
sublingual, 1227
submaxillary, 1226
subparotid, 1225
suburethral, 1495
sudoriferous, 1200
suprarenal, 1437
sweat, 1200
tarsal, 1149
thymus, 1414
thyroid, 1407
arteries of, 605
lymphatic vessels of, 782
veins of, 731
of tongue, 1101
tracheal, 1389
of Tyson, 1464
of v. Ebner, 1101
vulvo-vaginal, 1495
Glandulae Pacchioni, 737
Tysonii odoriferae, 1464
Glans clitoridis, 1494
penis, 1464
Glaserian fissure, 84, 1162
Gleno-humeral ligament, 307
Glenoid cavity, 176
fossa, 84, 135
ligament, 176
of Cruveilhier, 361
point of skull, 150
Glia-cells, 832
Gliosa, 882
centralis, 843, 847
cornualis, 843, 848, 852
Glisson, capsule of, 770, 1266
1337
Globulus of cerebellum, 900
Globus of epididymis, 1480
Glomeruli olfactorii, 964
Glosso-epiglottic ligament, 1373
Glosso-epiglottidean folds, 1374
Glosso-pharyngeal nerve, 1066
nuclei of, 890
surgical anatomy of, 1067
Glottis, chink of, 1377
false, 1377
respiratoria, 1377
true, 1377
vocalis, 1377
Gluteal artery, 695
inferior, 694
cutaneous nerve, 1028
glands, 794
line, anterior, 216
inferior, 216
posterior, 216
nerve, inferior, 1027
superior, 1027
1580
INDEX
Gluteal region, lymphatic vessel
of, 799
muscles of, 525
dissection of. 525
surgical anatomy of, 531
ridge, 226
veins, 761
Gluteo-femoral bursa, 333
Gluteus maximus muscle, 525
medius muscle, 526
minimus muscle, 526
Gnathic index of skull, 148
Golgi, cells of, 821,902
organ of, 831
Goll, column of, 839, 840, 850
Gomphosis, 266
Gonion, 124, 150
Gowers' tract, 901
Graafian follicles, 1514
vesicles, 1514
membrana granulosa of,
1515
ovicapsule of, 1515
Gracile lobe of cerebellum, 898
Gracilis muscle, 522
Granular sheath of Tomes, 1212
Gray commissure of cord, 844,
'845
substance of cord, 843, 855
Great auricular nerve, 989
cardiac nerve, 1086
plexus, 1090
vein, 770
deep petrosal nerve, 1049
occipital nerve, 986
omentum, 1266
sacro-sciatic foramen, 296
ligament, 294
sciatic nerve, 1030
sinus of aorta, 591
superficial petrosal nerve, 1048
Greater alar cartilage, 1107
wings of sphenoid, 95
Grooves, auriculo-ventricular, of
• heart, 5G7
basilar, 75
of pons, 877
bicipital, 179
carotid, 93
cavernous, 93
dentato-fascic-olar, 937
infraorbital, 107, 141
interventricular, 570
of heart, 507
intervertebral, 49
lachrymal, 107, 109, 141, 143
musculo-spiral, 181
mylo-hyoidean, 124
naso-palatine, 121
obturator, 217, 220
occipital, 86
optic, 93, 130, 131
peroneal, 248
popliteal 228
pterygopalatiiie, 116
sacral, 63
of spinal cord, 837
subclavian, 170
subcostal, 163
ulnar, 183
vertebral, 156
Ground bundle of cord, 849
dorsal column, 852
lateral column, 853
ventral column, 854
Gubernaculum testis, 1471
Gudden's commissure, 905, 1038
infracommissure of, 919
tractus peduncularis transver-
sus, 906
• Guerin, valve of, 1454
Gulf of internal jugular vein, 729
Gullet, 1235
Gums, 1205
surgical anatomy of, 1234
Gustatory cells, 1101
hair, 1101
nerve, 1052
path, 1067
pore, 1100
Gyre, angular, 931
callosal, 928, 930
cerebral, 922
dentate, 928
of frontal lobe, 929
hippocampal, 932
marginal, 931
medifrontal, 929
meditemporal, 932
mesorbital, 928, 930
olfactory, 935
paracentral, 929
parietal, 931
lobe, 931
paroccipital, 931
postcentral, 931
postparietal, 931
precentral, 929
preinsula, 933
subcalcarine, 932
subcallosal, 867
subcollateral, 932
subfrontal, 929
subtemporal, 932
superfrontal, 928, 929, 930
supertemporal, 932
supramarginal, 931
temporal lobe, 932
transtemporal, 932
uncinate, 932
Gyri Andrese Retzii, 938
Gyrus ambiens, 935
dentatus, 937
epicallosus, 938
fasciolaris, 938
intralimbicus, 937
semilunaris, 935
subcallosus, 936
H.VBENAL commissure, 915
Haemorrhoidal artery, inferior
691
middle, 688
superior, 680
gland, middle, 796
nerve, inferior, 1028
plexus, inferior, 1095
superior, 1095
veins, external, 760
inferior, 760
middle, 760
superior, 768
surgical anatomy of, 761
Hair, 1197
blood-vessels of, 1199
coats of, dermic, 1198
epidermic, 1198
cortical substance of, 1199
gustatory, 1101
nerves of, 1199
olfactory, 1110
Hair-bulb, 1197
Hair-follicle, 1197
Hair-papilla, 1197
root of, 1197
shaft of, 1199
stem of, 1199
Hair-streams, 1197
Hair-whirlpools, 1197
Haller, rete testis of, 1482
Hamstring muscles, 532
Hamular process of lachrymal,
113
of sphenoid, 90
Hamulus, 1178
Hand, arteries of, 6G2
bones of, 195
development of, 207
bursa of, 494
fasciae of, 493
ligaments of, 321
muscles of, 493
dissection of, 493
nerves of, from median, 1004
from radial, 1008
from ulnar, 1006
phalanges of, 206
veins of, 745
Hard palate, 1220
Harmonia, 266
Hastier, valve of, 1152
Ilaustra coli, 1325
Ilaversian canal, 38
Head, arteries of, 598
lymphatic glands of, 778
muscles of, surface form of,
387
veins of, 725
Heart, 564
arteries of, 580
auricles of, fibres of, 577
left, 570
sinus of, 570
right, 567
auriculo-ventricular fasciculus
of, 579
cavities of, capacity of, 566
component parts of, 567
endocardium, 576
fat upon, 566
fibrous rings of, 576
fore-chambers of, 567, 570
grooves of, auriculo-ventricu-
lar, 567
interventricular, 567
infundibulum of, 571
lymphatics of, 580
muscular fibres of, 577
myocardium, 576
nerves of, 580
position of, 564
size of, 566
structure of, 576
muscular, 577
surface form of, 580
surgical anatomy of, 580
veins of, 580
ventricle of, fibres of, 577
right, 571
ventricular portion of, 570
vortex of, 578
weight of, 566
Heel bone, 244
Heidenhain, demilunes of,
1228
Helicine arteries, 1468
Helicis major muscle, 1157
minor muscle, 1157
Helicotrema of cochlea, 1177
Helix, 1154
crus of, 1155
fossa of, 1155
muscles of, 1157
spine of, 1156
Helmholtz, ligaments of, 1170
Helwig, bundle of, 886
Hemiseptum, 921, 941
Hemispheres of cerebellum, 896
cerebral, 919
Hemolymph nodes, 774
INDEX
15X1
Henle, fenestrated membrane of
587
ligament of, 440, 444
loop of, 1427
spine of, 88
llcnsi'ii, canalis reunions of, 118(
' cells of, 1185
stripe, 1185
Hepatic area of kidneys, 1422
artery, 674, 1346
cells,*1346
ducts, 1350
flexure of colon, 1317
of large intestine, 1308
glands, 798
plexus, 1094
veins, 767
Hepato-colic ligament, 1 264
Hepa to-duodenal ligament, 1264
1 1 rpato-gastric ligament, 1264
Herbst, corpuscles of, 830
Hernia, congenital, 1535
diaphragmatic, 429
encysted, 1535
femoral, 1537
of funicular process, 1535
infantile, 1535
inguinal, 1532
direct, 1535
external, 1532
oblique, 1529, 1532
scrotal, 1533
surgical anatomy of, 1523
Hesselbach, ligament of, 440, 444
1529
triangle, 1532
Hey, ligament of, 517
Hiatus Fallopii, 88
sacralis, 62
semilunar, 747, 1110
tendineus, 524
Highmore, antrum of, 108
Hilton, compressor sacculi laryn-
gis muscle of, 1381
white line of, 1327
Hilum of dentatum of cerebellum,
900
of kidney, 1423
of ovary, 1513
of spleen, 1361
Hind-brain, 869
central connection of cranial
nerves, 888
external morphology of, 874
Hind-gut, 1246
Hinge-joint, 267
Hip, articulations of, 327
bursa of, 332
fasciae of, 525
ligaments of, 328
muscles of, 525
surface form of, 335
surgical anatomy of, 335
Hippocampal commissure, 951
digitations, 947
gyre, 932
Hippocampus, 936, 937, 947
gray substance of, 960
His, bundle of, 579
peripheral veil of, 818
sulcus terminalis of, 568
Histology of arteries, 586
of capillaries, 586
Homo-lateral tract-cells of cord,
855
Hook bone, 201
Horizontal cells of Cajal, 1135
lamina of ethmoid, 99
plate of palate bone, 116
semicircular canal, 1175
Horn cells of cord. 856
Horn cells of cord, lateral, 845
of cornua, dorsal, 844
ventral, 844
Horner's muscle, 373
Horny layer of skin, 1191
Horseshoe kidney, 1433
Houston's valves, 1326
llmvship's lacunae, 38
Huguier, canal of, 84, 1062
Humeral region, anterior, mus-
cles of, 476
posterior, muscles of, 479
Humerus, 179
articulations of, 185
attachment of muscles to
185
capitellum of, 183
development of, 184
lower extremity of, 182
nutrient canal of, 181
pressure curves of, 183
shaft of, 181
structure of, 183
surface form of, 185
surgical anatomy of, 185
trochlea of, 183
tuberosities of, 179
upper extremity of, 179
Humors of eye, 1138
Hunter's canal, 524, 699
Huschke, foramen of, 92
Hyaline cartilage, 262
Hyaloid canal of eye, 1 139
membrane of eye, 1139
Hydatids of Morgagni, 1480
non-pedunculated, 1480
pedunculated, 1480
Hymen, 1492
Hyo-epiglottic ligament, 1373
Hyo-glossus muscle, 399
Hyo-thyroid membrane, 1374
Hyoid artery of lingual, 606
of superior thyroid, 604
bone, 155
attachment of muscles to,
156
basi-hyal of, 155
body of, 155
borders of, 155
surfaces of, 1 55
cornua of, greater, 155
lesser, 155
development of, 156
region, infra-, muscles of, 393
supra-, muscles of, 396
surface form of, 156
surgical anatomy of, 156
tubercle of, 155
Hyparterial branch of bronchus,
1385
Hypochondriac region, 1243
Hypbgastric artery, 685
in foetus, 685
fold, 1531
nerve, 1017
plexus, 1089, 1095
region, 1243
vein, 760
Hypoglossal nerve, 1074
branches of, 1075, 1076
nuclei, 889
surgical anatomy of, 1077
Hypophysis, 917
posthypophysis, 917
prehypophysis, 917
Hyposylvian ramus, 925
rlypotnalamus, 867
optic portion of, external
morphology of, 917
hypophysis, 917
optic tract, 917
Hypothalamus, optic portion of,
terma, 917
tuber, 917
Hypothalamic tegmental sub-
stance, 915
Hyrtl, exsanguinated renal zone
of, 680, 1432
ILEO-APPENDICULAR fold, 1272
fossa, 1272
Ileo-caecal fossa, 1272
valve, 1315
fraenulum of, 1316
Ileo-colic artery, 677
fold, 1272
fossa, 1272
Ileum, 1297
Iliac arteries, circumflex, deep,
698
superficial, 704
common, 683
branches of, 683
compression of, 685
peculiarities of, 684
surface marking of, 684
surgical anatomy of, 684
external, 695
branches of, 697
surface marking of, 684,
696
surgical anatomy of, 696
internal, 685
branches of, 687
peculiarities of, 686
surface form of, 695
surgical anatomy of, 687
695
bursa, subtendinous, 333
fascia, 510
fossa, 216
furrow, 222
glands, 795
common, 796
external, 795
internal, 796
nerve, 1017
portion of fascia lata, 1540
region, muscles of, 510
surgical anatomy of, 513
vein, circumflex, deep, 759
common, 764
external, 759
internal, 760
Iliacus muscle, 512
tlio-capsularis muscle, 513
Ilio-coccygeus muscle, 456
Qio-costalis muscle, 421
tlio-femoral ligament, 330
[lio-hypogastric nerve, 1017
[lio-inguinal nerve, 1018
Qio-lumbar artery, 694
ligament, 293
veins, 764
[lio-pectineal bursa, 332
eminence, 217, 220
ligament, 510
line, 216
[lio-pelvic glands, 795
flio-sciatic notch, 217
;iio-tibial band, 237, 516
;iio-trochanteric ligament, 331
Ilium, 215
borders of, 217
crest of, 216
dorsum of, 215
processes of, 217
spine of, 217
surfaces of, 217, 216
1582
INDEX
Ilium, venter of, 216
Impar ganglion, 1078
Impression, deltoid, 181
gastric, 1340
Incisive fossa, 106, 123, 139
Incisor canal, 110
crest, 111
foramina, 110
nerve, 1053
teeth, 1206
Incisura cardiaca, 1401
inter-arytsenoidea, 1376
pancreatis, 1355
Incisures of Schmidt-Lauter
mann, 824
Incremental lines of dentine, 121
Incus, 1169
body of, 1169
ligaments of, 1171
processes of, 1169
Indices of skull, 147
Indusium, 938, 940
Infantile hernia, 1535
Inferior acromio-clavicular liga
ment, 301
alveolar artery, 616
branch of superior cervica
ganglion, 1084
calcaneo-scaphoid ligament
356
cardiac nerve, 1086
carotid triangle, 618
cerebral veins, 735
cervical-ganglion, 1086
constrictor muscle, 402
coronary artery of lip, 609
dental artery, 616
canal, 124
foramen, 124
nerve, 1053
ethmoidal turbinate bone, 101
external frontal artery, 630
gemellus muscle, 530
gluteal artery, 694
line, 216
nerve, 1027
hajmorrhoidal artery, 691
nerve, 1028
plexus, 1095
veins, 760
internal frontal arteries, 628
labial artery, 609
lachrymal gland, 1151
laryngeal artery, 643
veins, 751
lateral angle, 63
lingualis muscle, 401
longitudinal fasciculus, 962
sinus, 738
maxilla bone, 122
horizontal portion of, 122
maxillary bone, articulations
of, 125
attachment of muscles to,
125
development of, 125
horizontal portion of, bor-
ders of, 124
perpendicular portion of,
124
borders of, 124
processes of, 125
surfaces of, 124
nerve, 1050
meatus of nose, 145
medullary velum, 901
mesenteric artery, 679
plexus, 1094
vein, 768
nuchal line, 72
obliquus oculi muscle, 376
Inferior occipital fissure, 931
fossae, 133
olivary nucleus, 885
ophthalmic vein, 741
orbito-palpebral sulcus, 1147
palatine artery, 608
pancreatico-duodenal arter
677
petrosal sinus, 742
phrenic arteries, 682
veins, 767
profunda artery, 658
pubic ligament, 298
pudendal nerve, 1028
pyloric artery, 675
radio-ulnar articulation, 317
ramus of ischium, 218
of pubis, 220
rectus oculi muscle, 375
renal artery, 1432
sacro-seiatic foramen, 296
stephanion, 76, 150
sterno-pericardiac ligament,
560
superficial cerebellar veins, 73
tarsal arch, 625
thyroid artery, 643
veins, 751
transverse ligament, 304
turbinated bone, 119
articulations of, 120
borders of, 120
development of, 1 20
processes of, 120
surfaces of, 120
crest, 107, 117
vena cava, 764. See Postcava
vesical artery, 688
plexus, 762
vocal cords, 1378
.nflected fissure, 928
infraclavicular plexus, 790
nfracommissure of Gudden, 91f
nf racostales muscle, 427
nfraglenoid margin of tibia, 237
tubercle, 176
^nfrahyoid artery, 604
region, muscles of, 393
^nfralaryngeal glands, 785
nframandibular nerve, 1064
nframaxillary glands, 781
nerve, 1064
nfraorbital artery, 617
canal, 107, 140
foramen, 106, 140
groove, 107, 141
nerves, plexus of, 1063
nfrapatellar bursa, 342
nfraspinatus bursa, 307
fascia, 474
muscle, 474
bursa of, 475
nfraspinous fossa, 174
nfrasternal depression, 166
nfratemporal crest, 95
fossa, 138
iifratrochlear nerve, 1045
nfundibula of kidney, 1424
nfundibular artery, 593
recess of third ventricle, 917
nfundibuliforni fascia, 448, 1475
nfundibulo-pelvic ligament, 1502
nfundibulum of brain, 917
of ethmoid, 101
of Fallopian tube, 1510
of heart, 571
ngrassias, processes of, 96
nguinal canal, 450, 1529
fossa, 1258
external, 1532
internal, 1532
Inguinal fossa, middle, 1332
hernia, 1532
direct, 1535
- incomplete, 1536
oblique, 1529, 1532
lymphatic gland, deep, 794 .
superficial, 791
surgical anatomv of
794
region, 1243
Inion, 71, 150
Inlet of pelvis, 209
Inner condyle of femur, 228
Innominate artery, 596
branches of, 596
peculiarities of, 597
surgical anatomy of 597
bone, 213
vein, 750
left, 750
right, 750
Inosculation of arteries, 585
Insertion of muscles, 366
Inspiration, muscles of 434
Insula, 933
apex of, 933
development of, 925
fissure of, 933
pole of, 933
Integument of scrotum, 1473
Inter-alveolar cell islets, 1359
Interarticular chondro-sternal
ligament, 290
fibro-cartilage, 283, 300, 302
triangular, 317
ligament, 286, 331
sterno-costal ligament, 290
Interauricular furrow, 567
septum, 567
Inter-brain, 911
Intercalatum, 907
Intercarotid body, 602
Intercavernous sinus, 742
Intercellular biliary passages,
1348
Intercerebral cleft, 921
fissure, 921
Interchondral articulations, 291
ligament, external, 292
internal, 292
[nterclavicular ligament, 300
Intercolumnar fascia, 438, ] 474
1526
fibres, 438
!ntercondyloid notch, 227
intercostal arteries, 669
anterior, 646
collateral, 670
superior, 647
surgical anatomy of, 670
fascia, 426
glands, 807
muscles, 427
external, 427
internal, 427
nerves, 1011
abdominal, 1013
first, 1011
pectoral, 1011
surgical anatomy of, 1014
space, 156, 161
veins, 752
anterior, 752
posterior, 752
superior, left, 752
right, 752
ntercosto-humeral nerve, 1013
ntercrural space, 904
iterglobular spaces of Czermak,
1212
INDI:X
Interlobar arteries, 1432
lU.Mires, 924
Interlobular biliary plexus, 1345
ducts, 1349
Inter-maxillary bone, 110
region, muscles of, 381
suture, 139
Intenuecliul Insure, 931
Intermediate dorsal cutaneous
nerve, 1034
glands, 790
zone of kidney, 1424
Intormedio-lateral tract of cord,
853
Internal abdominal ring, 448,
1530
angular process, 80, 140
annular ligament, 545
anterior thoracic nerve, 1001
arcuate ligament, 429
auditory artery, 641
meat us, 133
bicipital ridge, 181
branches of superior cervical
ganglion, 1084
calcaneal nerve, 1031
calcanean artery, 718
calcaneo-astragaloid ligament,
354
calcaneo-cuboid ligament, 355
calcaneo-scaphoid ligament,
356
capsule, 955
carotid artery, 620
foramen, 88
plexus, 1083
circumflex artery of thigh, 70
condyle of femur, 228
crucial ligament, 339
cutaneous nerve, 1003, 1021
ear, 1173
«picoiidyle, 182
epigastric artery, 697
femoral region, muscles of, 522
iliac artery, 685
glands, 796
vein, 760
inguinal hernia, 1532
interchondral ligament, 292
Intercostal muscle, 427
jugular glands, 785
vein, 729
bulb of, 729
lateral ligament, 282, 312
malleolar artery, 718
malleolus, 238
mammary artery, 645
vein, 750
maxillary artery, 613
lymphatic glands, 781
vein, 727
•oblique line, 123
muscles, 439, 1528
•occipital crest, 74, 133
protuberance, 73
•orbital arteries, 628
«s, 1500
palpebral arteries, 625
plantar artery, 718
nerve, 1031
popliteal nerve, 1030
pterygoid muscle, 386
nerve, 1051
plate, 96
pudic artery in female, 693
in male, 690
vein, 760
rectus oculi muscle, 375
respiratory nerve of Bell, 992
saphenous nerve, 1022
vein, 756
Internal semiluiiarfibro-cartilage
340
spermatic fascia, 448
sphincter am muscle, \~>:\
structure of cerebellum, 899
supracondylar ridge, 1S1
tarsal ligament, 372
tuberosity of tibia, 236
wall of tympanum, 1162
Internasal suture, 139
Interneural articulations, 274
Internoclia or phalanges, 206
Interossei muscles of foot, 551
dorsal, 551
plantar, 551
of hand, 501
Interosseous artery of ulnar, 664
anterior, 664
posterior, 665
arteries, dorsal, 661, 715
palmar, 662
ligament, 288
nerve, anterior, 1004
dorsal, 1008
posterior, 1008
volar, 1004
sacro-iliac ligament, 294
veins of forearm, 747
Tnterpalpebral slit, 1148
Interparietal sulcus of Turner,
930
suture, 127
Interpeduncular ganglion, 908
Interpleural space, 1396
Interpubic disk, 298
Intersigmoid fossa, 1319
Interspinales muscle, 423
Interspinous ligaments, 275
Intersternal ligament, anterior,
292
posterior, 292
Intertransversales muscle, 424 [
laterales muscle, 424
mediates muscle, 424
Intertrarisverse ligaments, 275, ,
297
Intertrochanteric line, anterior,
225
posterior, 225
Intertubular cell-masses, 1359
tissue, 1213
Interventricular grooves, 570
of heart, 567
septum, 571
Inter vertebral disks, 272
fibro-cartilages, 272
foramina, 49
grooves, 49
notches, 49
substances, 272
veins, 755
Intestinal glands, 1303, 1327
Intestine, large, 1307
areolar coat of, 1325
arteries of, 1327
flexure of, hepatic, 1308
sigmoid,-1308
splenic, 1308
lymphatic glands of, 806,
1328
vessels of, 806
mucous membrane, 1326
muscular coat of, 1324
serous coat of, 1324
structure of, 1324
submucous coat of, 1325
veins of, 1328
innervation of, 1330
movements of, 1330
small, 1290
areolar coat of, 1298
Intestine, small, arteries of, 1304
lymphatic ghuids of, 805,
1305
vessels of, 806
mucous membrane of, 1298
muscular coat of, 1298
nerves of, 1307
serous coat of, 1298
| structure of, 1298
submucous coat of, 1298
veins of, 1305
villi of, 1300
surface form of, 1331
surgical anatomy of, 1331
Intestinurn tenue mesenteriale,
1297
liitracapsular fracture, 232
Intracartilaginous ossification, 43
L ntraepithelial plexus, 1121
Intralobular veins, 767
Intramembranous ossification, 43
Intraspinal venous plexuses, 732
Intrathyroid cartilage, 1371
Intrinsic muscles of tongue, 400
Intumescentia ganglioformis,
1059
Involuntary muscles, 363
Iris, 1127
arteries of, 1130
muscular fibres of, 1128
nerves of, 1130
pigment of, 1129
stroma of, 1128
structure of, 1128
Iregular bones, 34
Ischiatic lymphatic glands, 795
Ischio-capsular ligament, 330
Ischio-gluteal bursa, 333
Ischio-rectal fascia, 456, 1558
fossa, 1548
region, muscles of, 451
surgical anatomy of, 1547
Ischium, 217
body of, 217
ramus of, ascending, 218
descending, 218
spine of, 218
tuberosity of, 218
Island of Langerhans, 1359
of Reil, 933
Isthmus, aortic, 593
of auditory canal, 1158
of Fallopian tube, 1510
of fauces, 1222
faucium, 1204
gyri hippocampi, 932
of pharynx, 1231
of prostate gland, 1461
rhombencephali, 869
of thyroid gland, 1409
Iter chorda; anterius, 1162
posterius, 1161
Ivory of teeth, 1212
JACOB'S membrane, 1136
Jacobsori, cartilage of, 1107
eminence of, 1110
nerve, 1067
canal for, 90
organ of, rudimentary, 1110
Jaw, angle of, 124
lower, articulations of, 282
changes produced in, by age,
125
upper. See Maxillary bone.
Jejunum, 1297
Joints. See Articulations.
Jugular foramen, 73, 133
1584
INDEX
Jugular fossa, 91
ganglion, 1066
glands, internal, 785
lymphatic, trunk, 785
nerve, 1083
process, 73
tubercle, 74
vein, anterior, 728
external, 728
sinus of, 728
internal, 729
bulb of, 729
sinus of, 729
surgical anatomy of, 732
posterior external, 728
Juxta-aortic glands, left, 798
right, 797
Juxta-cervical lymphatic knot,
801
KERKRING, valves of, 1299
Key and Retzius, foramen of,
859, 978
Kidneys, 1418
abnormalities of, 1433
areas of, 1422
arteries of, 1432
borders of, 1423
calices of, 1424
capsule of, fatty, 1419
true, 1423
connective tissue of, 1433
cortical substance of, 1424
ducts of, 1429
hilum of, 1423,
horseshoe, 1433
infundibula of, 1424 ^
intermediate zone of, 1424
lymphatic vessels of, 802, 1433
Malpighian bodies of, 1426
capsule, 1426
tuft of, 1426
medullary substance of, 1425
minute anatomy of, 1426
nerves of, 1433
papillae of, 1425
pelvis of, 1424
pyramids of Ferrein, 1425
of Malpighi, 1425
sinus of, 1423
structure of, 1423
surface form of, 1434
surfaces of, 1420
surgical anatomy of, 1434
tubuli uriniferi, 1429
variations of, 1433
veins of, 1433
Knee, bursse of, 342
ligaments of, 337
Knee-cap, 233
Knee-joint, surface form of, 345
surgical anatomy of, 345
Kohn, epithelial corpuscles of,
1412
Kolliker, commissure of, 919
membrane of, 1185
Krause, ellipsoid of, 1137
end-bulbs of, 826, 830
Kiihne, muscle-spindle of, 830
LABIA pudendi majora, 1489
minora, 1490
Labial artery, inferior, 609
glands, 1204
nerves, 1048
Labium tympanicum, 1182
Labium vestibulare, 1182
Labyrinth, 1173
arteries of, 1186
membranous, 1 1 79
nerves of, 1186
osseous, 1174
veins of, 1186
Lachrymal apparatus, 1151
artery, 624
peculiarities of, 625
bone, 112
articulations of, 113
attachment of muscles to,
113
borders of, 113
crests of, 141
development of, 113
lesser, 113
surfaces of, 113
canaliculi, 1152
canals, 1152
caruncle, 1152
crest, 113
fossa, 81
glands, 1151
structure of, 1151
surface form of , 1152
surgical anatomy of, 1154
groove, 107, 109, 141, 143
nerve, 1043
notch, 107
papilla, 1148, 1152
process of inferior turbinated,
120
sac, 1152
surface form of, 1152
surgical anatomy of, 1153
sulcus, 113
tubercle, 109
Lactiferous duct, 1518
Lacuna magna, 1453
Lacuna;, 1120
of bone, 38
Howship's, 38
Lacus lacrimalis, 1148
Lagena, 1182
Lalouette, pyramid of, 1409
Lambda, 129, 150
Lambdoid suture, 75, 78, 123
Lamella of bone, articular, 251
Lamellated corpuscles, 830
Lamina basalis, 1124
of brain, dorsal, 870
ventral, 870
of cornea, 1119
cribrosa, 89
cribriform, 1118
of sclerotic, 1118
dental, 1215
of ethmoid, horizontal, 99
perpendicular, 100
vertical, 100
fusca, 1118
periclaustral, 954
reticularis, 1185
spiralis ossea of cochlea, 1177
suprachorioidea, 1122
vasculosa, 1122
of vertebra, 34
Lancisi, nerve of, 940
Landzert, fossa of, 1271
Langer, foramen of, 466, 648, 790
lines of cleavage of, 1190
Langerhans, centro-acinar cells
of, 1359
islands of, 1359
Large, deep petrosal nerve, 1049
1083
intestine, 1307
palatine nerve, 1049
superficial petrosal nerve, 1048
Laryngeal artery, inferior, 643
superior, 605
nerve, superior, 1071
external, 1071
internal, 1071
pouch, 1379
saccule, 1379
sinus, 1379
surface of epiglottis, 1373
veins, 751
Larynx, 1369
aperture of, superior, 1376
arteries of, 1383
cartilages of, 1380
cavity of, 1376
compartments of, 1376
lower, 1379
. middle, 1377
glands of, 1382
joints of, 1374
ligaments of, 1374
lymphatics of, 782, 1383
membranes of, 1374
mucous membrane of, 1382
muscles of, 1379
nerves of, 1384
rima glottidis, 1377
structure of, 1373
veins of, 1383
ventricle of, 1379
vocal cords of, false, 1378
true, 1377
Lateral angle, inferior, 63
area of oblongata, 876
calcaneal nerves, 1031
cell column, 846
cerebro-spinal fasciculus, 853
column of spinal cord, 840
fissures of cord, 845
horn-cells of cord, 856
ligament, external, 282
internal, 282
of liver, 1341
of wrist, 320
masses of atlas, 51
of ethmoid, 100
occipital fissure, 931
odontoid ligaments, 280
patellar ligaments, 337
phreno-pericardial ligaments,
561
plantar nerve, 1032
region of skull, 136
sacral artery, 694
veins, 760
sacro-coccygeal ligament, 297
sinus, 738
surgical anatomy of, 739
spinal arteries, 640
surface of liver, 1336
thoracic region, muscles of,
471
ventricle of brain, 941
body of, 941, 943
cells of, 941
choroid plexus of, 943
cornua of, 941
vertebral region, muscles of,
410
vestibulo-spinal tract of cord,
853
Lateralis nasi artery, 609
Latissimus dorsi muscle, 415
bursa of, 476
Leaf, intercondyloid glands of.
794
supracondyloid glands of, 794
Left bronchus, 1386
cardiac vein, 771
colic artery, 680
plexus, 1095
INDEX
1585
Left coronary artery, 593
plexus, 1090
vein, 770
fore-chamber of heart, 570
gastro-epiploic plexus, 1094
innominate vein, 750
juxta-aortie glands, 798
lobe of liver, 1340
lower azygos vein, 753
marginal vein, 771
superior intercostal vein, 7.YJ
upper azygos vein, 753
Leg, arteries of, 710
bones of, 233
fasciae of, 534
ligaments of, 327
muscles of, 534
nerves of, 1019
veins of, 755
Lemnisci, decussation of, 882
Lens, crystalline, 1140
epithelium, 1140
fibres, 1140
suspensory ligament of, 1139
Lenticula, 867,871,954
Lenticular ganglion, 1040
Lenticulo-striate arteries, 630
Lesser internal cutaneous nerve
1003
omentum, 1264
sacro-sciatic foramen, 296
ligament, 295
sciatic nerve, 1027
wing of sphenoid, 96
Levator anguli oris muscle, 379
scapula? muscle, 416
ani muscle, 453
preanal fibres of, 455
glandulse thyroidea? muscle
1409
labii inferioris muscle, 380
superior alaeque nasi muscle,
378
superioris muscle, 379
menti muscle, 380
palati muscle, 405
palpebrse muscle, 373
superioris muscle, 375
prostatae, 456
urethra?, 456
Levatores costarum muscle, 428
Lieberkiihn, crypts of, 1303
glands of, 1303, 1327
Lieno-renal ligament, 1261, 1362
Ligamenta alaria, 342
sacro-coccygea, anterior, 454
subflava, 274
suspensoria of mamma, 465
Ligamentous action of muscles,
270
Ligaments, 263
accessory, of atlas, 278
of acetabulum, transverse, 332
acromio-clavicular, inferior,
301
superior, 301
of ankle, 349
anmilar, anterior, 544
external, 545
internal, 545
of radius, 316
of stapes, 1171
anterior common, 271
longitudinal, 271
superior, 287
appendiculo-ovarian of Clado,
1312
arcuate, external, 429, 451
internal, 429
middle, 429
astragalo-scaphoid, 356
100
Ligaments, atlanto-axial, ante-
rior, 276
posterior, 277
atlo-axoid, anterior, 276
posterior, 277
of axilla, suspensory, 466
of Bertin, 330
of Rigelow, 330
of bladder, false, 1446
true, 1445
broad, of liver, 1340
of uterus, 1502
calcaneo-astragaloid, external,
354
internal, 354
posterior, 354
calcaneo-cuboid, internal, 355
long, 355
short, 355
superior, 355
calcaneo-navicular, 355
calcaneo-scaphoid, external,
355
inferior, 356
internal, 356
superior, 355
capsular. See Individual
joints.
carpo-metacarpal, 323
of carpus, 321
check, 280, 1115
chondro-sternal, anterior, 290
interarticular, 290
posterior, 290
chondro-xiphoid, anterior, 290
posterior, 290
ciliary, 1126
of Cloquet, 1476, 1477
coccygeal, 857
Colles', 439
conoid, 302
of Cooper, 439, 450
coraco-acromial, 303
coraco-clavicular, 302
coraco-humeral, 306
coracoid, 304
costo-clavicular, 300
costo-coracoid, 469
costo-transverse, long, 287 •
middle, 288
posterior, 288
costo- vertebral, anterior, 286
costo-xiphoid, anterior, 290
posterior, 290
cotyloid, 331
crico-arytenoid, 1375
crico-tracheal, 1376
cruciform, 277
deltoid, 350
dentate, 860
dorsal. See Individual joints,
duodeno-mesocolic, 1271
duodeno-renal, 1264
of elbow, anterior, 311
posterior, 311
femoral, 517
of fingers, 324
superficial, transverse, 496
Flood's, 306
of foot, 544
fundiform of Retzius, 544
gastro-splenic, 1266
Gimbernat's, 439, 1527
gleno-humeral, 307
glenoid, 176, 307
of Cruveilhier, 361
glosso-epiglottic, 1374
of hand, 321
of Helmholtz, 1170
of Henle, 440, 444
hepato-colic, 1264
Ligaments, hepato-duodenal, 1204
nepato-gMtric, 1264
of Hesselbach, 440, 444, 1529
of Hey, 517
of hip', 328
hyo-epiglottic, 1373
ilio-femoral, 330
ilio-lumbar, 293
ilio-pectirieal, 510
ilio-troL-hanteric, 331
of incus, 1171
infundibulo-pclvic, 1502
interarticular, 28(3, 331
interchondral, external, 292
internal, 292
interclavicular, 300
interosseous. See Individual
joints.
interspinous, 275
intersternal, anterior, 292
posterior, 292
inter trans verse, 275, 297
intervertebral, 272
ischio-capsular, 330
of jaw, 282
of knee, 337
alar, 342
anterior, 347
coronary, 342
crucial, 339
mucosum, 342
posterior, 337
transverse, 342
of larynx, 1374
lateral. See Individual joints,
of leg, 327
lieno-renal, 1261, 1362
of liver, 1340
coronary, 1341
falciform, 1340
lateral, 1341
round, 1342
suspensory, 1340
lumbo-sacra'1,293
of Luschka, 560
of malleus, 1170
of Mayer, 1416
metacarpal, 326
metacarpo-phalangeal, 326
metatarsal, 361
metatarso-pharyngeal, 361
nuchffi, 275, 415
oblique, 316
obturator, 298
occipito-atlantal, anterior, 278
posterior, 278
occipito-axial, 280
odontoid, lateral, 280
middle, 281
orbicular, 316
orbito-tarsal, 1149
of ossicula, 1170
palpebral, 1149
of patella, 337
pelvis, falciform, 295
transverse, 461
of penis, 1469
suspensory, 439
perineal, transverse, 461
of peritoneum, 1264
of phalanges of foot, 361
of hand, 327
phreno-colic, 1268
phreno-pericardial, 561
plantar, long, 355
short, 355
posterior common, 272
longitudinal, 272
Poupart's, 438, 1527
pterygo-mandibular, 383
pterygo-maxillary, 383
1586
INDEX
Ligaments, pubic, anterior, 298
inferior, 298
posterior, 298
superior, 298
pubo-capsular, 330
pubo-femoral, 330
pubo-prostatic, 1445, 1461
pubo-vesical, 1445
radio-carpal, 320
radio-ulnar, annular, 316
anterior, 317
oblique, 316
orbicular, 316
round, 316
posterior, 317
rhomboid, 300
sacro-coccygeal, anterior, 29(
lateral, 297
posterior, 296
sacro-iliac, anterior, 296
interosseous, 294
long, 294
oblique, 294
posterior, 294
short, 294
sacro-sciatic, anterior, 295
great, 294
lesser, 295
posterior, 294
sacro-uterine, 1502
sacro-vertebral, 293
of scapula, 303
Srhlemm's, 307
of shoulder, 305
spirio-glenoid, 304
spiral, of cochlea, 1182
spleno-phrenic, 1266
sterno-clavicular, anterior, 300
posterior, 300
sterno-costal, anterior, 290
interarticular, 290
posterior, 290
sterno-costo pericardial, 560,
561
sterno-pericardiac, 560
of stapes, 1171
of sternum, 292
stylo-hyoid, 397
stylo-mandibular, 283, 389
stylo-maxillary, 283
subpubic, 298
superior, of incus, 1171
suprascapular, 304
supraspinous, 275
suspensory, of clitoris, 439
of eye, 1115
of lens, 1139
of liver, 1340
of mamma, 465
of ovary, 1513
of penis, 439
of Treitz, 1294
sutural, 261
synovial, 264
tarsal, external, 373
internal, 373
of thumb, 323
thyro-epiglottic, 1375
thyro-hyoid, 1374
tibio-tarsal, anterior, 349
posterior, 349
transverse, of atlas, 277
humeral, 307
inferior, 304
of knee, 342
superior, of scapula, 304
trapezoid, 302
tympano-malleolar, 1166
utero-sacral, 1502
of uterus, 1501
round, 1503
Ligaments of vertebra?, 271
vertebro-pericardial, 560
vertebro-pleural, 1393
vesico-uterine, 1502
of Winslow, 337
of Wrisberg, 341
of wrist, 320
anterior, 320
dorsal, 320
lateral, 320
posterior, 320
volar, 320
xipho-pericardial, 561
Y-, 330
of Zinn, 375
Ligamentum arcuatum exter-
num, 429, 451
internum, 429
arteriosum, 589
conjugate, 286
corniculopharyngeum, 1376
crico-pharyngeum, 1376
epididymidis, 1480
hepatoduodenale, 1260
latum pulmonalis, 1392
mucosum, 342
nuchse, 275, 415
patella;, 337
posticum Winslowii, 337
pulmonale, 1392
spirale, 1182
suspensorium, 281
teres, 331
ventriculare, 1374
Light stimuli, path of, 1137
Limbic lobe, 936
Limbus alveolaris, 124
laminse spiralis, 1182
Limen insula% 933
Linea alba, 446
aspera, 226
quadrati, 226
Lina? semilunares, 447
transverse, of abdomen, 447
Line, gluteal, anterior, 216
inferior, 216
posterior, 216
ilio-pectineal, 216
nuchal, inferior, 72
superior, 72
temporal, 76, 80
Lingual artery, 605
branches of, 606
deep, 606
surgical anatomy of, 606
bone, 155
glands, 1101
nerve, 1052, 1067
branches of, 1052
region, muscles of, 398
dissection of, 399
tonsil, 1096
veins, 729
Lingualis muscle, inferior, 401
superior, 401
transverse, 401
vertical, 401
Lingula, 93, 282, 897
pulrronis, 1392
Lips, 1204
surgical anatomy of, 1234
Liquor Cotunnii, 1174
Lissauer, tract of, 851
Little brain, 895
Littre, glands of, 1453
Liver, 1334
abnormalities of, 1342
accessory, 1342
areolar coat of, 1345
arteries of, 1343
development of, 1253
Liver, ducts of, 1348
excretory apparatus of, 1349
fibrous coat of, 1345
fissures of, 1338
hepatic arteries, 1343
ducts, 1343
vein, 1344
ligaments of, 1340
lobes of, 1339
lobules of, 1345
lymphatics of, 802, 1349
margins of, 1337
movability of,. 1342
nerves of, 1349
portal vein, 1343
serous coat of, 1345
structure of, 1345
support of, 1342
surface relations of, 1353
surfaces of, 1336
surgical anatomy of, 1354
veins of, 1343
Lobe or lobes of brain, 923
central, 933
of cerebellum, 896, 897, 898
cerebral, 923
frontal, 926
fissures of, 926
gyres of, 929
of kidney, 1423
limbic, 936
of liver, 1339
of lungs, 1403
occipital, 931
fissures of, 931
gray substance of, 959
olfactory, 934
orbital, 926
parietal, 930
fissures of, 930
gyre of, 931
of prostate gland, 1461
temporal, 931
fissures of, 931
gyres of, 932
of testicle, 1482
of thymus gland, 1414
of thyroid gland, 1409
Lobule of ear, 1155
of kidney, 1423
of liver, ~1345
of lungs, 1404
of mamma, 1518
Lobuli testis, 1482
Locus cseruleus, 880
Long bones, 33
calcaneo-cuboid ligament, 355
ciliary arteries, 627
nerves, 1045
plantar ligament, 355
sacro-iliac ligament, 294
saphenous nerve, 1022
vein, 756
scrotal nerve, 1028
subscapular nerve, 1002
thoracic artery, 653
nerve, lOOO'
vein, 748
Longissimus dorsi muscle, 421
Longitudinal fibres of cord, 848
of pons, 887
sinus, inferior, 738
superior, 78, 130, 736
zones of brain, 870
Longus capitis muscle, 408
colli muscle, 409
Looped tubes of Henle, 1428
Louis, angle of, 157
Lowenthal's tract of cord, 854
Lower deep cervical glands, 785
extremity, arteries of, 698
INDEX
1587
Lower extremity, articulations
of, 327
bones of, 208
fasciae of, 509
ligaments of,' 327
lymphatic vessels of, 794
deep, 795
superficial, 795
muscles of, 509
surface form of, 552
surgical anatomy of, 554
nerves of, 1019
veins of, 7-V>
deep, 758
superficial, 756
jaw, articulation of, 282
subscapular nerve, 1001
Ludovic, angle of, .157
Lumbar arteries, 682
enlargement of spinal cord, 836
fascia, 418
ganglia, 1089
glands, 797
nerves, 1015
divisions of, dorsal, 1015
ventral, 1015
roots of, 1015
plexus, 1016
branches, 1017
surgical anatomy of, 1034
portion of gangliated cord,
1089
region, 1243
veins, 765
ascending, 753, 765
right, 752
vertebra:, 56
body of, 56
fifth, 57
laminae of, 56
pedicles of, 56
processes of, 57
Lumbo-iliac ligament, 293
Lumbo-inguinal nerve, 1018
Lumbo-sacral ligament, 293
plexus, 1015
Lumbricales muscle, foot, 549
hand, 501
Lungs, 1398
air-cells of, 1403
apex of, 1398
arteries of, 1404
base of, 1398
borders of, 1400
bronchus of, 1403
capillaries, 1404
color of, 1402
fissures of, 1402
foetal, 1402
lobes of, 1403
lobules of, 1404
lymphatics of, 1405
nerves of, 1405
parenchyma of, 1403
root of, 1402
serous coat of, 1403
structure of, 1403
subserous areolar coat of, 1403
svibstance of, 1402
surface form of, 1405
surfaces of, 1400, 1402
surgical anatomy of, 1406
veins of, 1405
weight of, 1402
Lunula of nails, 1195
Luschka, foramen of, 881 , 978
gland of, 1417
ligament of, 560
Luys, body of, 915
centrum medianum of, 914
Lymph canalicular system, 772
Lymph-capillaries, 772
Lymph-glands, parotid, 1225
Lymph-nodes, 774
Lymph-spaces, 772
perivascular, 772
Lymphatic or lymphatics, 772
of arm, 787
of arteries, 588
of bone, 41
of cranial region, 778
duct, right, 777
tributaries of, 778
of dura of brain, 974
extracranial, 778
of face, 778
glands, 774
of abdomen, 195
abdomino-aortic, 797
along mesenteric arteries,
798
of anus, 807
axillary, 787
brachial, 787
bronchial, 1389
buccal, 781
buccinator, 781
carotid, 785
cervical, deep, 785
superficial, 783
of Cloquet, 794, 795
coeliac, 798
colic, 806
condyloid of Leaf, 794
connected with coeliac axis
and branches, 798
diaphragmatic, 808
epigastric, superior, 800
of face, 778
femoral, deep, 794
gastric, 798
genial, 781
gluteal, 794
hsemorrhoidal, middle, 796
of head, 778
hepatic, 798
hypogastric, 796
iliac, 795
common, 796
external, 795
internal, 796
ilio-pelvic, 795
infralaryngeal, 785
inframaxillary, 781
inguinal, deep, 794
superficial, 791
intercostal, 808
intermediate, 790
of intestine, large, 806
small, 805
ischiatic, 794
jugular, external, 783
internal, 785
juxta-aortic, left, 798
right, 797
of lower extremity, 791
lumbar, 797
malar, 781
mammary, internal, 807
mastoid, 779
maxillary, internal, 781
mediastinal, anterior, 808
posterior, 808
middle, of Stahr, 784
of neck, 783
obturator, 795
occipital, 779
paramammary, 811
parietal, 807
parotid, 779
deep, 780
superficial, 779
Lymphatic or lymphatics glands,
pectoral, 788
of pelvis, 795
peritracheo-bronchial, 809
popliteal, 794
post-pharyngeal, 784
posterior auricular retro-
auricular, 779
pre-aortic, 797
pre-auricular, 779
prelaryngeal, 785
pretracheal, 786
rectal, 806
retro-aortic, 798
retro-crural, 795
retro-pharyngeal, 784
of Rosenmiiller, 794
sacral, 797
saphenous, external, 794
scapular, 788
splenic, 798
sterno-mastoid, 785
subclavian, 790
submaxillary, 784
submental, 784
suboccipital, 779
suborbital, 781
subparotid, 781
substerno-mastoid, 785
supraclavicular, 785
supraconclyloid of Leaf,
794
supra-epitrochlear, 787
suprahyoid, lateral, 784
median, 784
supramaxillary, 781
supratrochlear, 787
surgical anatomy of, 775
of thoracic wall, 807
tibial, anterior, 794
tracheal, 786
of upper extremity, 787
deep, 787
superficial, 787
visceral, 808
zygomatic, 781
pharyngeal ring, 1234
vessels of abdomen, 799
walls of, deep, 799
superficial, 799
of bile-ducts, 803
of bladder, 800
cardiac, 812
cerebral, 778
of cranial region, 781
of face, 782
of Fallopian tube, 801
of gluteal region, 799
of head, 781
of heart, 580
of intestines, large, 806
small, 806 '
of kidney, 802
of larynx, 782
of leg, 794
of liver, 802
of lower extremity, 794
deep, 795
superficial, 795
of lung, 812
meningeal, 778
of mouth, 782
of neck, 778, 786
of nose, interior of, 782
of oesophagus, 813
of ovary, 801
of pancreas, 804
of pelvis, 799
of penis, 799
of perineum, 799
of peritoneum, 800
1588
INDEX
Lymphatic or lymphatics vessels
of pharynx, 782
pleural, 812
of prostate gland, 800
pulmonary, 812
of scrotum, 799
of seminal vesicles, 802
of spleen, 804
of stomach, 804
of suprarenal capsule, 802
of testicle, 802
of thoracic trachea, 813
wall, 810
thymic, 813
of thyroid gland, 782
of tongue, 782
of umbilicus, 799
of upper extremity, 790
deep, 790
superficial, 790
of ureter, 802
of urethra, female, 801
male, 801
of uterus, 801
of vagina, 802
of vas deferens, 802
Lyra, 951
M
McBuRNEY's point, 1311
Macula acustica sacculi, 1180
cribrosa, 1174
lutea, 1138
Magnum of carpus, 201
Majendie, foramen of, 859, 881,
978
Malar bone, 113
articulations of, 115
attachment of muscles to,
115
borders of, 115
development of, 115
processes of, 114
surfaces of, 113
canal, 114
foramen, 113
glands, 781
nerve, 1046, 1062
point of skull, 150
process of superior maxillary,
109
Male breast, 1522
surgical anatomy of, 1522
organs of generation, 1457
perinseum, 1549
urethra, 1450
Malleolar artery, 713, 718
Malleolus, external, 241
internal, 238
Malleus, 1168
handle of, 1168
head of, 1168
ligaments of, 1170
manubrium of, 1168
neck of, 1168
processes of, 1168
spur of, 1168
Malpighi, pyramids of, 1425
Malpighian bodies of kidney,
1426
of spleen, 1365
capsule, 1426
layer of skin, 1192
tuft, 1426
Mamma, 1516
areola of, 1516
arteries of, 1520
ligament of, suspensory, 465
lobule of, 1518
lymphatics of, 1520
Mamma, nerves of, 1520
variations in, 1517
veins of, 1520
Mammary artery, external, 653
internal, 645
branches of, 646
surgical anatomy of, 647
glands, 1516
description of, 1516
internal, 807
lymphatics of, 810
surgical anatomy of, 811
structure of, 1518
surgical anatomy of, 1520
tissue, prolongations of, 1518
vein, internal, 750
Mammillary duct, 1518
process of lumbar vertebra, 57
Mandible, 122
Mandibular artery, 616
fossa, 84
nerve, 1050
region, muscles of, 380
dissection of, 380
Manubrium of malleus, 1168
of sternum, 157
Marchi and Lowenthal, tract of
cord, 853
Marginal artery, 592
fasciculus, anterior, 854
gyre, 931
tract of cord, 851
vein, left, 771
Marrow of bone, 36
Marshall, vein of, oblique, 771
vestigial fold of, 563
Martinotti, nerve-cells of, 960
Masseter muscle, 383
Masseteric artery, 616
fascia, 383
nerve, 1051
vein, 727
Mast-cells, 36
Masto-occipital suture, 75, 128
Masto-parietal suture, 128
Mastoid air-cells, 1163
antrum, 87
artery, 611, 612
cells, 86
foramen, 85, 138
fossa, 86
lymphatic glands, 779
nerves, 990
process, 86, 138
vein, 728
Matrix of nails, 1195
Maxillary antrum, orifice of, 145
artery, external, 607
internal, 613
bone, inferior, 122
articulation of, 125
attachment of muscles to,
125
development of, 125
horizontal portion of, 122
borders of, 124
surfaces of, 122
perpendicular portion of,
124
borders of, 124
processes of, 125
surfaces of, 124
superior, 105
articulations of, 112
attachment of muscles to,
112
body of, 105
siu faces of, 106
development of, 112
processes of, 109
hiatus, 107
Maxillary lymphatic glands, in-
ternal,781
nerve, inferior, 1050
superior, 1046
branches of, 1046
process of inferior turbinated
bone, 120
of malar bone, 115
of palate bone, 118
region, superior, muscles of, 379
sinus, 108
tuberosity, 106
vein, internal, 727
Mayer, ligaments of, 1416
Meatus, auditory, external, 88,
138, 1158
internal, 89, 133
of nose, inferior, 145
middle, 145
superior, 101, 144
urinarius, male, 1453
female, 1492
Meckel, band of, 1170
cave of, 973
diverticulum, 1298
ganglion, 1048
branches of, 1048
Medial accessory olivary nuclei,
885
calcaneal nerve, 1031
dorsal cutaneous nerve, 1034
plantar nerve, 1031
Median nerve, 1004
branches of, 1004
vein, 745
basilic, 746
cephalic, 746
cerebral, 735
Mediastinal arteries, 646
posterior, 668
glands, anterior, 808
posterior, 808
pleura, 1394
subpleural, 646
space, 1396
surface of lungs, 1399
Mediastinum, 1396
anterior, 1396
arteries of, 1397
lymphatics of, 1398
middle, 1396
posterior, 1396
superior, 1396
testis, 1482
veins of, 1398
Medicerebellar artery, 642
Medicerebral artery, 629
branches of, 629.
veins, 735
Medicornu, 945
Medidural artery, 615
veins, 734
Medifrontal fissure, 927
gyre, 929
Medio-tarsal joint, 352, 357
Medipeduncles of cerebellum, 901
Meditemporal fissure, 932
gyre, 932
Medulla oblongata, 874. See
Oblongata.
Medullary portion of suprarenal
capsule, 1440
of thymus gland, 1416
sheath of Schwann, 824
spaces of bone, 45
substance of kidneys, 1425
vela, 901
velum, 901
Medullated axis-cylinder pro-
cesses, 824
Medulli-spinal veins, 755
INDEX
1589
Megacephalic skull, capacity of
147
Meibomian glands, 1149
structure of, 1150
surgical anatomy of, 1153
Meissner and Wagner, touch
corpuscles of, 830
Membrana basilaris, 1182
cochlea cluctus cochlearis, 1 182
elastica laryngis, 1375
flaccida of Shrapnell, 1166
limitans externa of retina, 1136
interim, 1132
nietitans, 1151
pupillaris, 1'130
quadrangularis, 1374
sacciformis, 319
tectoria, 1185
tymparii, 1165
arteries of, 1167
lymphatics of, 1168
nerves of, 1168
secundaria, 1177
structure of, 1167
veins of, 1167
Membrane, basilar, 1182
Bowman's, 1119
of brain, arachnoid, 976
meningeal, 972
of Bruch, 1124
of choroid, 1122
of Corti, 1185
costo-coracoid, 469
crico-thyroid, 1375
of Demours, 1120
of Descemet, 1120
fenestrated, of Henle, 587
hyaloid, 1139
hyo-thyroid, 1374
of Jacobs, 1136
of Kolliker, 1185
Nasmyth's, 1214
obturator, 528
occipito-atlantal, anterior, 278
posterior, 278
otolith, 1182
of Reissner, 1182
of Scarpa, 1162
of Shrapnell, 1166
of spinal cord, 856
arachnoid, 858
surgical anatomy of, 860
sutural, 236, 973
synovial, 264
tliyro-hyoid, 1374
Membranous canal of cochlea,
1182
cranium, 102
labyrinth, 1179
portion of urethra, 1451
semicircular canals, 1180
Meningeal artery, 611, 612
anterior, 623
middle, 615
surgical anatomy of, 615
posterior, 640
small, 616
lymphatic vessels, 778
membranes of brain, 972
veins, 730, 734
Meuinges of brain, 972
Meningo-rachidian veins. 754
Meiiisco-femoral joint, 344
Menisco-tibial joint, 344
Meniscus, 283
Mental foramen, 123, 140
nerve, 1053
point of skull, 150
process, 122, 140
protuberance, 122
spines, 123
Mental tubercles, 122
.Merkel, filtrum ventriculi of,
1376
Mesenrrphalon, 904
Mesenteric arteries, glands along,
798
artery, inferior, 679
superior, 677
ganglion, 1094
plexus, inferior, 1094
superior, 1094
vein, inferior, 768
superior, 768
Mesenterico-mesocolic fold, 1271
Mesenterico-parietal fold, 1273
Mesentery, 1266
development of, 1248
glands, 805
of vermiform appendix, 1269
Meso-exo-gnathion suture, 111
Meso-gnathous skull, index of,
148
Mesoappendix, 1269
Mesoblastic somites, 1245
MesocEecum, 1309
Mesncele, 907
Mesochorium, 1471
Mesocolic area of kidney, 1422
band, 1325
fossa, 1271
Mesocolon, ascending, 1268
descending, 1268
sigmoid, 1269
transverse, 1268, 1317
Mesogastrium, 1248
Mesognathion suture, 111
Mesophalic skull, capacity of, 147
Mesorbital gyre, 928, 930
Mesorectum, 1269
Mesosalpinx, 1502
Mesosternum, 157
Mesovarium, 1502, 1512
Metacarpal bones, 202
ligament, transverse, 326
spaces, 203
Metacarpo-phalangeal articula-
tions, 326
surface form of, 327
Metacarpus, 202
articulations of, 206
common character of, 202
development of, 207
peculiar characters of, 203
Metaplexuses, 881
Metapore, 859, 881, 978
Metasternum, 159
Metatarsal artery, 715
bones, 252
fifth, 254
first, 252
fourth, 254
peculiar characters of, 252
second, 252
third, 253
ligament, transverse, 361
Mctatarso-phalangeal articula-
tions, 361
Metatarsus, 252
articulations of, 254
common characters of, 252
development of, 255
Metatela, 879, 902, 981
Metathalamus, 914
Metopic suture, 83, 127
Meynert, commissure of, 919
fasciculus retroflexus, 908
Microcephalic skull, capacity of,
147
Mid-brain, 869, 904
aqueduct of, 907
crusta of, 910
Mid-brain, deep origin of cranial
nerves in, 910
gray masses of, 910
intercalatum of, 907
pes of, 910
pyramidal tract of, 910
structure of, external, 905
internal, 906
substantia nigra of, 907
tegmentum of, 908
fibre tracts of, 908
Middle arcuate ligament, 429
cardiac nerve, 1086
cerebral artery, 629
cervical ganglion, 1085
clinoid processes, 93, 132
colic artery, 678
constrictor muscle, 403
costo-trans verse ligament, 288
cutaneous nerve, 1021
ear, 1160
fossa of skull, 130
hsemorrhoidal artery, 688
gland, 796
veins, 760
inguinal fossa, 1532
internal frontal artery, 629
meatus of nose, 145
mediastinum, 1396
meningeal artery," 615
veins, 734
odontoid ligament, 52, 281
palatine nerve, 1050
sacral artery, 683
veins, 764
spermatic fascia, 442
subscapular nerve, 1002
superior dental nerve, 1047
temporal artery, 613
vein, 727
thyroid vein, 730
turbinated bone, 101
vesical artery, 688
Mid-gut, 1246
Milk teeth, 1206
Minor cardiac nerve, 1086
Mitral nerve-cells, 960
orifice, 570
Mixed bones, 34
Mobile septum, 1107
Moderator band, 572
Modiolus, 1177
Molar glands, 1205
teeth, 1208
Molecular nerve-cells, 958
Moll, glands of, 1148
Monakow's tract of cord, 853
tractus rubrospinalis, 908, 909
Monaxonic neurones, 823
Monopolar dendrites, 821
Monro, foramen of, 866, 913
sulcus of, 916
Mons Veneris, 1490
Montgomery, glands of, 1516
Monticulus cerebelli, 896
Morgagni, columns of, 1326
crypts of, 1326
hydatids of, 1480
sinus of, 404
valves of, 1326
Motor end-plates, 828
neurones, 816
root of spinal cord, 836
Mouth, 1203
angle of, 1203
aperture of, 1203
cavity of, 143
proper, 1204
floor of, lymphatic vessels of,
782
mucous membranes of, 1204
1590
INDEX
Mouth, muscles of, 379
surface form of, 1229
surgical anatomy of, 1234
vestibule of, 1204
Movable spleen, 1363
Movements admitted in joints,
268
Mucilaginous glands, 265
Mucous alveoli, 1228
coat of bladder, 1447
of gall-bladder, 1351
of oesophagus, 1239
of pharynx, 1233
of urethra, 1453, 1456
glands of tongue, 1228
Miiller's muscle, 376
"ring" muscle, 1126
Multifidus spina; muscle, 423
Multipolar cells, 820
Muscle or muscles, 363
of abdomen, 434
deep, 451
superficial, 434
abductor hallucis, 547
indicis, 501
minimi digiti, foot, 548
hand, 500
pollicis, 497
accelerator urinse, 459
accessorius ad ilio-costalem,
421
of acromial region, 472
adductor brevis, 523
longus, 522
magnus, 523
minimus, 523
obliquus hallucis, 549
pollicis, 499
transversus hallucis, 551
pollicis, 499
anconeus, 489
antitragicus, 1157
of arm, 472, 476
arteries of, 364
aryteno-epiglottideus, 1381
arytenoid, 1383
arytenoideus, 1380
attollens auriculam, 371
attrahens auriculam, 371
of auricular region, 371
azygos uvulae, 407
of back, 412
biceps, arm, 477
flexor cubiti, 477
thigh, 532
bipenniform, 365
biventer cervicis, 422
Bowman's, 1125
brachialis anticus, 478
buccinator, 382
bulbo-cavernous, 459
bundles, 363
cervicalis ascendens, 421
chondro-glossus, 399
ciliary of eye, 1125
circumflexus, 406
coccygeus, 457
complexus, 422
compressor narium minor, 378
nasi, 378
sacculi laryngis, 1381
urethras in female, 464
in male, 462
constrictor, isthmi faucium,
400, 407
pharyngeus, inferior, 402
middle, 403
superior, 403
urethrte, in female, 464
in male, 462
coraco-braehialis, 477
Muscle or muscles, corrugator
cutis ani, 451
supercilii, 373
of cranium, 367
cremaster, 441, 1528
crico-arytenoid, posterior, 1380
crico-thyroid, 1380
crureus, 520
deltoid, 472
depressor alae nasi, 378
anguli, oris, 380
labii inferioris, 380
detrusor urinas, 1446
diaphragm, 429
digastric, 396
dilator naris anterior, 378
posterior, 378
of dorsal region, 546
ejaculator seminis, 459
urinse, 459
erector clitoridis, 463
penis, 460
spinae, 419
of expiration, 434
of expression, 387
extensor brevis digitorum, 546
pollicis, 491
carpi radialis brevior, 487
longior, 487
ulnaris, 489
coccygeus, 424
communis digitorum, 488
indicis, 492
longus digitorum, 536
pollicis, 491
minimi digiti, 489
ossis metacarpi pollicis, 491
primi internodii pollicis, 491
proprius hallucis, 535
secundi internodii pollicis,
491
of face, 367
of femoral region, anterior, 514
internal, 522
posterior, 532
fibres, 363
structure of, 364
of fibular region, 542
flexor accessorius, 549
brevis digitorum, 547
hallucis, 549
minimi digiti, foot, 550
hand, 500
pollicis, 499
carpi radialis, 481
ulnaris, 482
longus digitorum, 541
hallucis, 541
pollicis, 484
ossis metacarpi, 500
pollicis, 498
profundus digitorum, 484
sublimis digitorum, 483
of foot, 544
of forearm, 480
frontalis, 369
fusiform, 365
gastrocnemius, 537
gemellus, inferior, 530
superior, 529
genio-glossus, 399
genio-hyo-glossus, 399
genio-hyoid, 397
of gluteal region, 525
gluteus maximus, 525
medius, 526
minimus, 526
gracilis, 522
hamstring, 532
of hand, 493
of head, 367
Muscle or muscles, helicis major,
1157
minor, 1157
Hilton's, 1381
of hip, 525
Horner's, 373
of humeral region, anterior,
476
posterior, 479
hyo-glossus, 399
of iliac region, 510
iliacus, 512
ilio-capsularis, 513
ilio-coccygeus, 456
ilio-costalis, 421
of infra-hyoid region, 393
infracostales, 427
infraspinatus, 474
insertion of, 366
of inspiration, 434
intercostal, 427
external, 427
internal, 427
of intermaxillary region, 381
interossei of foot, 551
of hand, 501
interspinales, 423
intertransversales, 424
lateralis, 424
mediates, 424
involuntary, 363
of ischio-rectal region, 451
of larynx, 1381
latissimus dorsi, 415
of leg, 534
levator anguli oris, 380
scapulae, 416
ani, 453
glandulce thyroideas, 1409
labii inferioris, 380
superioris, 379
alaeque nasi, 378
menti, 380
palati, 405
palpebrae, 373
superioris, 374
prostatae, 456
urethra;, 456
levatores costarum, 428
ligamentous action of, 270
of lingual region, 398
lingualis, inferior, 401
superior, 401
transverse, 401
vertical, 401
longissimus dorsi, 421
longus capitis, 408
colli, 409
of lower extremity, 509
lumbricales, foot, 549
hands, 499
of mandibular region, 380
masseter, 383
of maxillary region, 379
Miiller's, 376
multifidus spin®, 423
mylo-hyoid, 397
naso-labialis, 381
of natal region, 378
of neck, 387
nerves of, 364
oblique, ascending, 439
descending, 435
external, 435
internal, 439, 1528
obliquus auriculae, 1157
capitis inferior, 424
superior, 424
oculi, inferior, 376
superior, 376
obturator externus, 531
1591
Muscle or muscles, obturator
hit emus, 528
occipitalis, 369 .
occipito-frontalis, 369
omo-hyoid, 395
opponens minimi digiti, 500
pollicisj 498
orbicular, 365
orbicularis oris, 381
palpebrarum, 372
orbital, 376
region, 374
of palatal region, 405
palato-glossus, 400, 407
palato-pharyngeus, 407
of palmar region, middle, 501
palmaris brevis, 500
longus, 482
of palpebral region, 372
pectineus, 522
pectoralis major, 466
minor, 470
of pelvic outlet, 451
penniform, 365
of perinaeum in female, 462
in male, 457
peroneus brevis, 543
longus, 542
tertius, 537
of pharyngeal region, 402
pharyngo-glossus, 400
of plantar region, 547
plantaris, 539
platysma myoides, 388
popliteus, 540
pronator quadratus, 485
radii teres, 481
psoas magnus, 512
parvus, 512
of pterygo-mandibular region,
385
pterygoid, external, 386
internal, 386
pubococcygeus, 454
pyramidalis abdominis, 446
nasi, 378
pyriformis, 527
quadratus femoris, 530
lumborum, 451
menti, 380
quadriceps extensor, 518
quadrilateral, 365
of radial region, 486, 497
of radio-ulnar region, poste-
rior, 488
recto-urethralis, 456
recto-uterinus, 1503
rectus abdominis, 444
capitis anticus major, 408
minor, 409
lateralis, 409
posticus major, 424
minor, 424
femoris, 518
oculi, external, 375
inferior, 375
internal, 375
superior, 375
retrahens auriculum, 371
rhomboidal, 365
rhomboideus major, 416
minor, 416
"ring" of Miiller, 1126
risorius, 383
rotatores spinae, 423
sacro-lumbalis, 421
salpingo-pharyngeus, 407
Santorini's, 383
sartorius, 518
scalenus anticus, 410
medius, 410
Muscle or muscles, scalenus pos-
ticus, 411
of scapular region, anterior
473
posterior, 474
semicircular, of rectum, 1325
semimembranosus, 533
semispinalis colli, 423
dorsi, 423
semitendinosus, 533
serratus magnus, 471
posticus inferior, 417
superior, 417
of shoulder, 472
skeletal, 363
of sole of foot, 547
soleus, 538
sphincter, 365
ani, external, 452
internal, 453
vagina?, 463
spinalis colli, 422
dorsi, 421
spindle of Kiihne, 830
splenius, 418
capitis, 418
colli, 418
sterno-cleido-mastoid, 391
sterno-hyoid, 394
sterno-mastoid, 391
sterno-thyroid, 394
striated, 363
striped, 363
stylo-glossus, 399
stylo-hyoid, 397
stylo-pharyngeus, 405
subanconeus, 480
subclavius, 470
subcrureus, 521
subscapularis, 473
of superficial cervical region,
388
supinator longus, 486
radii brevis, 489
of supra-hyoid region, 396
supraspinales, 423
supraspinatus, 474
suspensory, of duodenum, 1294
temporal, 384
of temporo-mandibular region
383
tensor fasciae femoris, 517
palati, 406
tarsi, 373
tympani, 1171
teres major, 475
minor, 475
of thigh, 514
of thoracic region, anterior,
465
lateral, 471
of thorax, 426
thyro-arytenoid, 1381
thyro-epiglottideus, 1381
thyro-hyoid, 395
tibialis anticus, 535
posticus, 541
of tibio-fibular region, 534
of tongue, 400
extrinsic, 400
intrinsic, 400
trachelo-mastoid, 421
tragicus, 1157
transversalis abdominis, 444,
1528
cervicis, 421
colli, 421
transversus auriculae, 1157
menti, 380
perinei superficialis, in fe-
male, 462
Muscle or muscles, transversus
perinei superficialis, in male,
459
trapezius, 413
triangular, 365
triangularis menti, 380
sterni, 427
triceps, 479
extensor cubiti, 479
of trunk, 412
of ulnar region, 500
unstriated, 363
unstriped, 363
of upper extremity, 464
of ureters, 1446
vastus externus, 520
internus, 520
vegetative, 363
veins of, 364
of vertebral region, anterior,
408
lateral, 410
voluntary, 363
zygomaticus major, 379
' minor, 379
Muscular coat of anal canal,
1324
of bladder, 1446
of duodenum, 1296
of intestine, large, 1324
small, 1298
of o?sophagus, 1238
of rectum, 1324
of stomach, 1282
of vermiform appendix, 1312
fibres, cardiac, 363
portion of urethra, 1451
structure of heart, 577
substance of tongue, 400
Musculi papillares of ventricle,
left, 575
right, 572
pectinati of auricle, left, 570
right, 568
pubo-vesicalis, 1446
Musculo-cutaneous nerve, 1002,
1034
Musculo-phrenic artery, 646
Musculo-spiral groove, 181
nerve, 1007
branches of, 1007
Myelencephalon, 874
Myelin sheath, 824
Myelinic axones, 824, 826
Myelinization of axones of cord,
855
Myelocele, 845
Myelon, 834
Mylo-hyoid artery, 616
muscle, 397
ridge, 123
Mylo-hyoidean groove, 124
Myocardium, 576
Myrtiform fossa, 106
N
NABOTH, ovules of, 1505
Nails, 1195
body of, 1195
edge of, 1195
lunula of, 1195
matrix of, 1195
ridges of, 1195
ungual fold of, 1195
wall of, 1195
Nares, anterior, 142, 1108
posterior, 142, 1108
septum of, 142
Nasal angle, 105
1592
INDEX
Nasal artery from internal max-
illary, 617
from ophthalmic, 626
of septum, 609
transverse, 626
bones, 104
articulations of, 105
attachment of muscles to
105
borders of, 105
development of, 105
surfaces of, 105
cartilages, 1106
cavity, 142
crest,' 111, 116
duct, 1152
fossae, 142, 1108
arteries of, 1111
atrum of, 1110
inner wall of, 1110
lymphatics of, 1112
mucous membrane of, 1110
nerves of, 1112
outer wall of, 1109
surgical anatomy of, 1112
veins of, 1111
groove, 105
nerve, 1044
branches of, 1045
notch, 80
portion of pharynx, 1231
process, 80
of superior maxillary, 109
region, muscles of, 378
slit, 143
spine, 80
anterior, 111, 139, 143
posterior, 116, 135, 143
venous arch, 725
Nasion, 80, 139, 150
Nasmyth's membrane, 1214
Naso-frontal vein, 740
Naso-labial ridge, 380
Naso-labialis muscle, 381
Naso-maxillary suture, 139
Naso-palatine artery, 617
canal, 121
groove, 121
nerve, 1050
Naso-pharynx, 1231
Nates of quadrigemina, 905
Navicular bone, 249
articulations of, 249
attachment of muscles to,
249
surfaces of, 249
tuberosity of, 249
Neck, arteries of, 598
fascise of, 387
lymphatic glands of, 778, 783
vessels of, 786
muscles of, 387
triangles of, posterior, 620
surgical anatomy of, 618
veins of, 724, 728
Nelaton's line, 232
Nerve or nerves, 825
abducent, 1057
accessory, 1073
acoustic, 1064 .
afferent, 827
ansa hypoglossi, 1077
of arm, 994
Arnold's, 1070
of arteries, 588
articular, of anterior tibial
1033
of auriculo-temporal, 1052
of great sciatic, 1030
of internal plantar, 1032 •
popliteal, 1031
Nerve or nerves, articular, oi
peroneal, 1033
of posttibial, 1031
of ulnar, 1006, 1186
auditory, 1064
auricular, anterior, 1052
posterior, 1062
of vagus, 1070
auriculo-temporal, 1052 -
beginnings, peripheral, 828
of centripetal neurones
828
blood-vessels of, 826
of bones, 41
buccal, 1051
from facial, 1063
buccinator, 1051
calcaneal, lateral, 1031
medial, 1031
calcaneo-plantar, 1031
cardiac, cervical, 1072
great, 1086
inferior, 1086
middle, 1086
minor, 1086
superior, 1085
thoracic, 1072
cardio-motor, 1081
carotico-tympanic, 1083
carotid, 1067
cavernous, large, 1095
small, 1095
centrifugal, 827
centripetal, 827
cerebral, 1036
cervical, 986
superficial, 990
cervico-facial, 1063
chorda tympani, 1052, 1061
ciliary, long, 1045
short, 1045
circumflex, 1002
coccygeal, 1023
cochlear, 1064, 1186
communicantes hypoglossi, 988
communicating, fibular, 1031
tibial, 1031
of Cotunnius, 1050
cranial, 1036
crural, anterior, 1021
accessory of Winslow,
1020 '
cutaneous, of abdomen, 1013
external, 1002, 1018
intermediate dorsal, 1034
internal, 1003, 1021
plantar, 1032
lateral, 1018
medial dorsal, 1034
middle, 1021
of musculo-cutaneous, 1034
musculo-spiral, 1008
of obturator, 1020
palmar, 1004
of perineal, 1028
of peroneal, 1033
of small sciatic, femoral,
1028
gluteal, 1028
perineal, 1028
of supraorbital, 1044
of thorax, 1012
of ulnar, 1006
dorsal, 1006
palmar, 1006
dental, anterior superior, 1048
inferior, 1053
middle superior, 1047
posterior superior, 1047
descendens hypoglossi, 988
norii, 1076
Nerve or nerves, digastric, from
facial, 1062
digital, foot, 1032
hand, 1005
dorsal, 1010
of clitoris, 1030,
of penis, 1030
dorsi-lumbar, 1016
of dura of brain, 974
dural, 1046
from hypoglossal, 1076
of inferior maxillary, 1051
of vagus, 1070
efferent, 827
eighth, 1064
eleventh, 1073
of eyeball, 1038
facial, 1059
femoral, 1021
fifth, 1041
first, 1037
ventral cutaneous, 1011
of foot, 1032
fourth, 1041
frontal, 1043
ganglia of, 827
spinal, 983
ganglion of ciliary, 1040
lenticular, 1040
of Scarpa, 1065
vestibular, 1065
gastric, 1072
genito-crural, 1018
femoral, 1016
glosso-pharyngeal, 1066
gluteal, inferior, 1027
superior, 1027
gustatory, 1052
huemorrrioidal, inferior, 1028
of heart, 580
hypogastric, 1018
hypoglossal, 1074
iliac, 1017
ilio-hypogastric, 1017
ilio-inguinal, 1018
ncisor, 1053
nframandibular, 1064
nframaxillary, 1064
nfraorbital, 1062
nfratrochlear, 1045
ntercostal, 1011
intercosto-humeral, 1013
interosseous, anterior, 1004
dorsal, 1008
posterior, 1008
of tibial, 1034
volar, 1004
Jacobson's, 1067
jugular, 1083
labial, 1048
of labyrinth, 1186
lacrimal, 1043
of Lancisi, 940
laryngeal, of vagus, inferior,
1071
superior, 1071
external, 1071
internal, 1071
lingual of fifth, 1052
of glosso-pharvngeal, 1067
lumbar, 1015
lumbo-inguinal, 1018
malar, 1062
of superior maxillary, 1046
mandibular, 1050
masseteric, 1051
mastoid, 990
maxillary, inferior, 1050
superior, 1046
median, 1004
mental. 1053
INDEX
1593
Nerve or nerves, muscular, of ex-
ternal plantar, 1033
of great sciatic. KYM
of hypoglossal, 1077
of internal plantar, 1032
popliteal, 1031
of musculo-cutaneous, 103-4
of musculo-spiral, 1007
of perineal, 1030
of posttibial, 1031
of sciatic plexus, 1027
of tibial, 1033
of ulnar, 1006
museulo-cutaneous, 1002, 1034
musculo-spiral, 1007
mylo-hyoid, 1053
nasal, 1044
from Meokel's ganglion, 1048
ganglionie hraneli of, 1045
na>o-palatine, 1050
ninth, 1066
obturator, 1020
accessory, 1020
occipital, from facial, 1062
great, 986
small. 989
oculomotor, 1039
nucleus of, 911
<esophageal, 1072
olfactory, 1037
ophthalmic, 1043
optic, 1038
orbital, of superior maxillary,
1046
origin of, 827, 828
palatine, anterior, 1049
external, 1050
large, 1049
middle, 1050
posterior, 1050
small, 1050
palmar, of ulnar, 1006
palpebral, 1048
parotid, 1052
perforating, of Casserius, 1002
of pericardium, 563
pericrania!, 1044
perineal, 1028
peroneal, 1030
common, 1033
deep, 1033
petrosal, deep, 1083
great deep, 1049
superficial, 1048
large deep, 1049, 1083
superficial, 1048
pharyngeal, 1050, 1067, 1070
phrenic, 992
of pia of brain, 982
plantar, lateral, 1032
medial, 1031
plexus of, 826
abdominal aortic, 1094
adrenal, 1092
annular, 1121
brachial, 994
cardiac, 1090
carotid, internal, 1083
cavernous, 1083
cervical, 989
dorsal, 984
coccygeal, 1034
cceliac, 1072, 1094
colic, left, 1095
coronary, 1090, 1094
cystic, 1094
of dental, superior, 1048
epigastric, 1091
fundamental, 1121
gastric, 1094
gastro-duodenal, 1094
Nerve or nerves, plexus of, gastro-
epiploic, ID!) I
left, 1094
luemorrhoiclal, inferior, 109;
superior, 1095
hepatic, 1094
hvpogastric, 1095
infraorbital, 1062
int fa-epithelial, 1121
lumbar, 1016
mesenteric, inferior, 1094
superior, 1094
oesophageal, 1069, 1072,
1091
ovarian, 1094
pancreatic, 1095
patellar, 1021
pelvic, 1095
pharyngeal, 1067
phrenic, 1092
prostatic, 1095
pudendal, 1026
pudic, 1026
pulmonary, 1091
dorsal, 1069, 1072
ventral, 1069, 1072
pyloric, 1094
renal, 1072, 1093
sacral, 1026, 1095
dorsal, 984
sciatic, 1026
sigmoid, 1095
solar, 1091
spermatic, 1094
splenic, 1072, 1094
subclavian, 1086
subepithelial, 1121
suprarenal, 1092
thoracic aortic, 1087
tympanic, 1067
uterine, 1095
utero-vaginal, 1095
vaginal, 1095
vertebral, 1086
vesical, 1095
pneumogastric, 1068
popliteal, external, 1033
internal, 1030
portio dura, 1059
mollis, 1060
posttibial, 1031
pterygoid, external, 1051
internal, 1051
pterygo-palatine, 1050
pudendal, inferior, 1028
pudic, 1028
pulmonary, dorsal, 1072
ventral," 1072
radial, 1008
recurrent, of internal maxil-
lary, 1051
laryngeal, of vagus, 1071
respiratory, of Bell, external,
1000
internal, 992
sacral, 1023
saphenous, 1222
external, 1031
internal, 1022
long, 1022
short, 1031
scapular, posterior, 999
of Scarpa, 1050
sciatic, great, 1030
small, 1027
scrotal, long, 1028
second, 1038
seventh, 1059
sixth, 1057
spermatic, external, 1018
spheno-palatine, 1047
Xervc or nerves, sphenoidal, 1054
spinal, 982
accessory, 1073
splanchnic, 1087
renal, 1088
stylo-hyoid, 1062
subcutaneous mala?, 1047
suboccipital, 986
subscapular, 1001
superficial colli, 990
supra-acromial, 992
supraclavicular, 991
supramandibular, 1063
supramaxillary, 1063
supraorbital, 1044
suprascapular, 1000
suprasternal, 991
supratrochlear, 1044
sural, 1033
sympathetic, 827
system, 815
cell-element of, 816
development of, 816
structure of, 819
supporting tissue elements
of, 832
temporal, of auriculo-tempo-
ral, 1052
deep, 1051
from facial, 1062
of superior maxillary, 1046
temporo-malar, 1046
tenth, 1068
termination of, 828
third, 1039
thoracic, 1010
anterior, 1001
long, 1009
posterior, 1001
thoracico-lumbar, 1014
thyro-hyoid, 1077
thyroid! 1086
tibial, 1030
tissue, chemical composition
of, 833
development of, 818
tonsillar, 1067
trifacial, 1041
trigeminal, 1041
trochlear, 1041
nucleus of, 910
twelfth, 1074
tympanic, 1067
from facial, 1061
ulnar, 1005
vagus, 1068
vasomotor, 1081
vestibular, 1065
Vidian, 1048
Nerve-cells, 820
axone of, 823
body external morphology,
' of, 820
internal morphology of,
822
of cerebral cortex, 958
dendrites of, 822
of Martinotti, 960
mitral, 960
Nerve-endings in muscle, 364
Nerve-fibre, axis-cylinder of, 823
Nerve-fibres, 825
centrifugal, 827
centripetal, 823
cerebral, 961
cortex, 959
commissural, 963
projection, 963
thalamo-frontal, 956
thalamo-striate, 956
vasomotor, 826
1594 '
INDEX
Nerve-paths, 825
Nervi nervorum, 826
Nervous papilla?, 1191
Nervus cutaneus patellae, 1022
intermedius, 894
superficialis cordis, 1085
Neumann, dentinal sheath of,
1213
Neural arch, 34
tube, 817
Neuraxone, 820
Neurenteric canal, 1252
Neuri lemma of cord, 824
amyelinic axones with, 825
without, 825
nucleus of, 825
Neurite, 820
Neuroblasts, 818
Neuro-central suture, 59
Neuro-muscular spindles, 830
Neuro-tendinous spindles, 830
Neuroglia of cord, 818, 832
Neurones, 816, 820
afferent, peripheral axone of,
819
centripetal, peripheral nerve,
beginnings of, 828
diaxonic, 823
excito-glandular, 816
excito-motor, 816
forms of, 820
monaxonic, 823
motor, 816
polyaxonic, 823
sensor, 816
peripheral axone of, 819
theory of, 831
Neuropore, 863
Nexal root of eighth nerve, 1065
Nidus avis of cerebellum, 898
larvngei, 890
pharyngei, 890, 892
Ninth nerve, 1066
surgical anatomy of, 1067
Nipple, 1516
structure of, 1518
Nissl's bodies, 822
Nodal point, 1116
Nodes, hemolymph, 774
Nodular lobe of cerebellum, 898
Nose, 1105
aperture of cartilage of, 1107
arteries of, 1108
cartilage of, 1106
dorsum of, 1106
fossa; of, 142, 1108
integument of, 1107
interior of, lymphatic vessels
of, 782
lymphatics of, 1108
meatus of, inferior, 145
middle, 145
superior, 101, 144
mucous membrane of, 1108
muscles of, 1107
nerves of, 1108
outer, 1106
septum of, 142
cartilage of, triangular, 1107
structure of, 1106
veins of, 1108
Notch, cotyloid, 220
ethmoidal, 82
ilio-sciatic, 217
intercondyloid, 227
intervertebral, 49
lachrymal, 107
nasal, 80
popliteal. 236
pre-occipital, 922
pre-sternal, 157
Notch, ptervgoid, 96
of Rivinus, 1161
sacro-sciatic, 211
great, 217
lesser, 218
scapular, great, 175
sigmoid, 125
spheiio-palatine, 118
supraorbital, 80, 140
suprascapular, 175
suprasternal, 411
thyroid, 1370
Nuchal line, inferior, 72
superior, 72
plane, 72
Nuck, canal of, 1472, 1513
Nuclei of abducent nerve, 894
of accessory nerve, 890
of acoustic nerve, 892
of cerebellum, 899
of cochlear nerve, 892
of facial nerve, 893
of glosso-pharyngeal nerve, 890
of hypoglossal nerve, 889
of origin, 889
pontius, 887
of termination, 889
of trigeminal nerve, 894
of vagus nerve, 890
vestibular nerve, 893
Nucleus, accessory cuneate, 884
alae cinerea?, 891
ambiguus, 890, 892
arcuatus, 886
dentate of cerebellum, 900
emboliformis, 900
fastigii, 900
funiculi cuneati, 876
teretis, 886
globosus, 900
incertus, 888
intercalatus, 886
lateralis, 886
lentis, 1142
of oculomotor nerve, 911
of olive, 885
superior, 887
postremus, 886
ruber, 908
semilunaris, 914
of Stilling, 847
tegmenti, 908
trochlear nerve, 910
Nuel, space of, 1185
Nuhn and Blandin, glands of,
1101
Nutrient artery of femur, 706
of fibula, 717
of humerus, 658
of tibia, 718
Nymphse, 1490
OBELION, 129, 150
Obex, 881
Oblique diameter of pelvis, 210
inguinal hernia, 1529, 1532
complete, 1533
incomplete, 1533
ligament, 316
line of clavicle, 169
of fibula, 240
of radius, 192
of tibia, 237
muscles, ascending, 439
aponeuiosis of, 441
descending, 435
external, 435
aponeurosis of, 435
Oblique muscles, internal, 439.
1528
aponeurosis of, 441
dissection of, 443
ridges of scapula, 172
of trapezium, 200
of ulna, 190
sacro-iliac ligament, 294
sinus of pericardium, 562
vein of Marshall, 771
Obliquus auriculas muscle, 1157
capitis inferior muscle, 424
superior muscle, 424
oculi muscle, inferior, 376
superior, 376
Oblongata, 874
areas of, 875
fissures of, 874
funiculus cuneatus of, 876
gracilis, 876
lateralis of, 876
olive of, 876
pyramids of, 875
restis of, 876
tuberculum cinereum of, 876
veins of, 736
Obstetric perinseum, 1490
Obturator artery, 689
peculiarities of, 690
bursa, 333
canal. 528
crest, 220
externus muscle, 531
fascia, 1558
foramen, 220
groove, 217, 220
internus muscle, 528
bursa of, 528
ligament, 298
membrane, 528
nerve, 1020
accessory, 1020
vein, 761
Occipital artery, 610, 642
branches of, 611
bone, 71
angles of, 75
articulations of, 76
attachment of muscles to, 76
borders of, 75
development of, 75
structure of, 75
surfaces of, 71
bulb, 946
crest, external, 72, 136
internal, 74, 133
diploic vein, 734
fissures, 926, 931
inferior, 931
lateral, 931
fossa;, inferior, 133
groove, 86
lobe, 931
fissures of, 931
gray substance of, 959
lymphatic glands, 779
nerve of facial, 1062
great, 986
small, 989
point of skull, 150
protuberance, external, 71, 136
internal, 73
sinus, 739
triangle, 620
vein, 727
Occipitalis muscle, 369
Occipito-atlantal ligament, ante-
rior, 278
posterior, 278
Occipito-axial ligament, poste-
rior, 280
INDEX
1595
Occipito-frontalis muscle, 369
surgical anatomy of, 369
Oecipito-parietal suture, 128
Occipito-pontile tract, 956, 957
Occiput, arteries of, 610
Oculomotor nerve, 1039
nucleus of, 911
sulcus, 904
surgical anatomy of, 1040
Odontoblasts, 1216
ofWaldeyer, 1211
Odontocla-sts, 1219
Odontoid ligaments, lateral, 280
middle, 52, 281
process of axis, 52
CEsophageal arteries, 643, 668
nerves, 1072
opening of diaphragm, 432
of stomach, 1278
plexus, 1069, 1072, 1091
veins, 751
(Esophagus, 1235
abdominal portion of, 1236
anomalies of, 1238
areolar coat of, 1239
arteries of, 1239
cervical portion of, 1236
diaphragmatic port ion of, 1236
innervation of, 1240
lymphatics of, 813, 1240
movements of, 1240
mucous coat of, 1239
muscular coats of, 1238
nerves of, 1240
relations of, 1237
structure of, 1238
submucous coat of, 1239
surgical anatomy of, 1240
thoracic portion of, 1236
veins of, 1239
Olecranon bursa, 313
subcutaneous, 479
fossa, 183
process, 186
Olfactory bulb, 867, 934
gray substance of, 960
cells, 1111
fissure, 928
foramina, 143
gyre, 935
hair, 1111
lobe, 934
postolfactory division of, 935
preolfactory division of, 934
nerve, 1037
surgical anatomy of, 1038
pathways, 964
striae, 935
tract, 867, 934, 935
tubercle, 935, 1037
Olivary body, 876. See Olive,
eminence, 93
nucleus superior, 887
process, 93, 131
Olive, 885
nucleus of, 885
accessory, 885
of oblongata, 876
Olivo-cerebellar fibres, 886
Olivo-spinal tract of cord, 853
Omenta, 1264
Omental band, 1325
tuberosity, 1336
Omentum, development of, 1250
gastro-colic, 1266
gastro-hepatic, 1264
gastro-splenic, 1266
great, 1266
lesser, 1264
Omo-hyoid muscle, 395
Opercula of insula, 925
Operculum, 925
Ophryon, 80, 150
Ophthalmic artery, 624
ganglion, i o \.~>
nerve, 1043
veins, 740
inferior, 741
superior, 740
Opisthion, 150
Opisthotic portion of tempora
bone, 91
Opponens minimi digiti muscle
foot, 550
hand, 500
pollicis muscle, 498
Optic axis, 1115
chiasm, 1038
commissure, 131, 1038
cup, 1131
disk, 1131
foramen, 93, 96, 131, 142
groove, 93, 130, 131
nerve, 1038
surgical anatomy of, 1038
papilla, 1131
path, 1038
radiations, 914, 956
tract, 1038
central connections of, 917
vesicles, 865
Ora serrata, 1130
Oral cavity, 1203
portion of pharynx, 1231
of tongue, 1097
Orbicular bone, 1169
ligament, 316
muscles, 365
Orbicularis oris muscle, 381
palpebrarum muscle, 372
external portion of, 372
internal portion of, 372
orbital portion of, 372
palpebral portion of, 372
Orbiculus ciliaris, 1125
Orbit, 140
arteries of, 624
fasciae of, 377
margin of, 106
muscles of, 376
Orbital artery, 613
internal, 628
branch of facial nerve, 1046
cavities, 140
fascia, 377
fissure, 96
foramina, 95
fossse, 140, 143
index of skull, 147
muscle, 376
nerve, 1046
operculum, 925
plates, 81
process of malar bone, 114
of palate bone, 1 18
region, muscles of, 374
dissection of, 374
surgical anatomy of, 377
septum, 1149
sinus, 118
vein, 727
Orbito-frontal fissure, 927
Orbito-palpebral sulcus, inferior,
1147
superior, 1147
Orbito-tarsal ligament, 1149
Orbits, 140
Organ of Corti, 1183
of Jacobson, 1110
Organs of digestion, 1203
of generation, female, 1489
male, 1457
Organs of Giraldes, 1484
of Golgi, 831
of respiration, 1369
of Rosenmiiller, 1511
of special sense, 1097
of voice, 1369
Orifice, mitral, 570
of prostatic ducts, 1451
tricuspid, 569
of ureters, 1447
Ortho-gnathous skull, index of,
148
Os acetabulum, 220
external, 1501
incae, 76
innominatum, 213
articulations of, 222
attachment of muscles to,
222
development of, 221
ilium, 214
ischium, 217
pubis, 219
structure of, 221
internal, 1500
magnum of carpus, 201
articulations of, 201
attachment of muscles to,
201
surfaces of, 201
planum of ethmoid, 100
trigonum, 247
uteri, 1501
Osborn, supracommissure of, 915
Ossa pubis, articulations of, 298
angle of, 219
unguis, 113
Osseous labyrinth, 1174
portion of Eustachian tube.
1164
of external auditory meatus,
1159
Ossicle, pterion, 103
Ossicles of tympanum, 1168
articulations of, 1170
ligaments of , 1170
movements of, 1171
Oss'fication of bone, 42
centre of, 44
intracartilaginous, 43
intramembranous, 43
of spine, 60
Osteo-dentine of Owen, 1214
Osteoclasts, 36
Osteology, 33
Ostium abdominale of Fallopian
tube, 1510
Otic ganglion, 1053
branches of, 1053
Otokonien, 1181
Otolith, 1179
membrane, 1182
Outer condyle of femur, 228
Outlet of pelvis, 21 1
3va, primordial, 1515
Ovarian arteries, 681
plexus, 1094
veins, 766
>vary, 1512
arteries of, 1515
connections of, 1513
descent of, 1513
at different ages, 1513
fimbria of, 1512
hilum of, 1513
lymphatic vessels of, 801
lymphatics of, 1515
nerves of, 1515
serous covering of, 1514
stroma of, 1514
structure of, 1514
1596
INDEX
Ovary, supports of, 1513
surgical anatomy of, 1515
veins of, 1515
Ovicapsule of Graafiaii follicles
1514
Ovules of Naboth, 1505
Ovum, discharge of, 1515
Oxyntie cells, 1285
glands, 1285
PACCHIONIAN bodies, 979
depressions, 78
glands, 737
Pacinian corpuscles, 830
Pads of adipose tissue, 265
Palatal index of skull, 147
region, muscles of, 405
dissection of, 405
surgical anatomy of, 408
Palate, 1220
bone, 115
articulations of, 119
attachment of muscles to,
119
development of, 119
horizontal plate of, 116
perpendicular plate of, 117
processes of, 118
tuberosity of, 117, 135
vertical plate of, 117
hard, 1220
muscles of, 405
soft, 1221
surgical anatomy of, 1234
vail of, 1221
Palatine aponeurosis, 406
artery, ascending, 608
descending, 617
inferior, 608
posterior, 617
surgical anatomy of, 617
•canal, anterior, 143
posterior, 107, 116
accessory, 116, 135
foramen, great, 116
posterior, 135
fossa, anterior, 110, 133
glands, 1221
nerve, anterior, 1049
external, 1050
large, 1049
middle, 1050
posterior, 1050
small, 1050
process of superior maxillary
bone, 110
spine, 116
veins, 727
Palato-glossus muscle, 400, 407
Palato-maxillary canal, 107
Palato-pharyngeus muscle, 407
Palmar arch, deep, 660
superficial, 666
surface marking of, 667
surgical anatomy of, 667
cutaneous nerve, 1004
fascia, deep, 495
surgical anatomy of, 496
interosseous arteries, 662
plexus of nerves, 745
recurrent arteries, 662
region, middle, muscles of, 501
veins, 747
Palmaris brevis muscle, 500
longus muscle, 482
Palpebral arteries, external, 625
internal, 625
fasciae, 1149
Palpebral ligaments, 1149
nerves, 1048
portion of conjunctiva, 1150
region, muscles of, 372
dissection of, 372
Pampiniform plexus of veins, 765
Pancreas, 1355
arteries of, 1360
body of, 1357
borders of, 1357
development of, 1254
dissection of , 1355
head of, 1357
lymphatic vessels of, 804
lymphatics of, 1360
neck of, 1357
nerves of, 1360
peritoneal relations of, 1358
structure of, 1359
surface form of, 1360
surfaces of, 1357
surgical anatomy of, 1360
tail of, 1358
veins of, 1360
Pancreatic area of kidney, 1414
artery, 676
duct, 1359
juice, 1360
plexus of nerves, 1094
Pancreatica magna artery, 676
Pancreatico-duodenal artery,
inferior, 677
superior, 676
plexus of nerves, 1094
vein, 768
Papilla, bile, 1296
dentine, 1215
lachrymal, 1152
spiralis, 1183
Papilla? circumvallate, 1099
conical, 1100
filiform, 1100
fungiform, 1100
maximae, 1099
mediae, 1100
minimse, 1100
simple, 1100
structure of, 1100
of tongue, 1099
Papillary layer of skin, 1191
Paracentral fissure, 928
gyre, 930
Paraduodenal fossa, 1271
Paramammary gland, 811
Paramastoid process, 73
Paramesal fissure, 927
Parametrium, 1501
Paranucleus, 1359
Paraplexus,.943, 945, 946
Parasympathetic bodies, 1417
Parathyroid glands, 1412
embryology of, 1413
structure of, 1413
surgical anatomy of, 1413
Paraxones, 823
Parenchyma of lungs, 1403
of testicle, 1482
Paries carotica, 1163
jugularis, 1161
labyrinthica, 1162
mastoidea, 1162
tegmentalis, 1161
Parietal artery, 613
arteries, ascending, 630
bone, 76
articulations of, 79
attachment of muscles to,
79
development of, 78
surfaces of, 76
borders of, 78
Parietal cells of gastric glands,
1285
diploic vein, external, 734
eminence, 76
fissure, 930
foramen, 76
gyre, 931
layer of pleura, 1393
lobe, 930
fissures of, 930
gyre of, 931
lymphatics, 807
peritoneum, 1257
surface of liver, 1337
of stomach, 1278
Parieto-colic fold, external, 1273
internal, 1273
Parieto-sphenoidal artery, 630
Parieto-temporal artery, 630
Paro-ophoron, 1512
Paroccipital fissure, 930
gyre, 931
Parolfactory sulcus anterior. 935
posterior, 935
Parotid capsule, 1226
duct, 1225
structure of, 1226
surface form of, 1225
fascia, 389, 1225
gland, 1224
accessory, 1225
arteries of, 1226
duct of, 1225
lymph, 1225
lymphatics of, 1226
nerves of, 1226
veins of, 1226
lymphatic glands, 779 •
deep, 780
superficial, 779
nerves, 1052
recess, 1225
Parotideo-masseterica fascia, 389
Parovarium, 1511
Pars ciliaris retinas, 1125, 1130
intermedia of Wrisberg, 1059
iridica retinae, 1130
Parvidural artery, 616
Patella, 233
apex of, 234
articulations of, 234
attachment of muscles to, 234
borders of, 234
development of, 234
ligaments of, 337
structure of, 234
surface form of, 234
surfaces of, 233
surgical anatomy of, 234
Patellar bursa, deep, 521
plexus, 1021
Path of light stimuli, 1137
Paths, gustatory, 1067
optic, 1038
Pecquet, reservoir of, 775
Pecten ossis pubis, 219
Pectineus muscle, 522
nerve to, 1022
Pectoral fascia, deep, 466
gland, 788
intercostal nerve, 1011
region, dissection of, 465
ridge, 181
Pectoralis muscle, major, 46&
minor, 470
Peduncles of callosum, 936
cerebellar, 900
medi peduncle, 901
postpeduncle, 900
prepeduncle, 901
Pelvic colon, 1317
IX DUX
1597
Pelvic fascia. 1. '>."><>
ligament, transverse, 461
plexus, 1 ()<>.->
portion of gangliated cord
1089
Pelvis, 209
axes of, 211
brim of, 209
cavity of. 210, 1440
boundaries of. 1 I Id
contents of, 1440
diameters of, 210
diaphragm of, 1241
differences between male anc
female, 212
false. 2119
of kidney, 1424
lower circumference of, 211
lymphatic vessels of, 799
lymphatics of, 795
muscles of, 451
outlet of, 211
position of, 211
surface form of, 222
surgical anatomy of, 222
true, 209
inlet of, 209
superior circumference of,
209
veins of, 755
Pendulous portion of urethra,
1452
Penile portion of urethra, 1452
Penis, 1463
arteries of, 1469
dorsal, 693
body of, 1465
corpora cavernosa of, 1465
corpus spongiosum, 1468
crura of, 1464
dorsum of , 1465
frcenum of, 1465
ligaments of , 1469
lymphatic vessels of, 799
lymphatics of, 1469
nerves of, 1030, 1470
dorsal, 1030
prepuce of, 1465
root of, 1464
septum of, 1467
structure of, 1465
surgical anatomy of, 1470
veins of, 1469
dorsal, deep, 762
superficial, 762
Penniform muscles, 365
Peptic cells of glands, 1285
glands, 1285
Perforated space, anterior, 935
Perforating arteries, anterior, 646
of hand, 662
of thigh, 706
cutaneous nerve, 1028
nerve of Casserius, 1002
Pericsecal folds, 1271
fossse, 1271
Pericardiac arteries, 646, 668
Pericardial pleura, 1394
sac, 1246
Pericardiothoracic cavity, 1246
Pericardium, 559
arteries of, 563
fibrous layer of, 560
nerves of, 563
serous, 562
sinus of, oblique, 562
transverse, 562
structure of, 560
surgical anatomy of, 563
vestigial fold of, 563
Pericementum, 1206
Perichondnum, 2<il, 262
Periclioroidal space, 111-8
Penelaustral lamina. 054
Pericrania! nerves, 1044
Perilymph space, 1174
Perimysimn, '.M> 1
Perineal artery, superficial, 691
transverse, 692
body, 1322, 1496, 1555
cutaneous nerve, 1028
fascia, deep, 1550
ligament, transverse, 461
nerve, 1028
Perineum, 1322, 1496
dissection of, 1547
in female, 1554
muscles of, 462
lymphatic vessels of, 799
in male, 1549
central tendinous point of,
1549
fascia3 of, 457
muscles of, 457
obstetric, 1490
surgical anatomy of, 1547
Perineurium, 826
Periosteum, 37
dental, 1214
Peripheral axone of afferent
neurone, 819
branches of lumbar portion of
gangliated cord, 1089
of middle cervical ganglion,
1086
of pelvic portion of gangli-
ated cord, 1089
of sacral portion of gangli-
ated cord, 1089
of superior cervical gan-
glion, 1083
of thoracic portion of gan-
gliated cord, 1087
nerve beginnings, 828
of centripetal neurones,
828
pathway, 964
veil of His, 818
Peritoneal coat of duodenum,
1296
of stomach, 1281 .
relations of pancreas, 1358
Perisclerotic lymph-space, 1113
Peritoneum, 1255
development of, 1245, 1252
ligaments of, 1264
lymphatic vessels of, 800
surgical anatomy of, 800
mesenteries of, 1266
omenta of, 1264
parietal, 1257
structure of, 1256
surgical anatomy of, 1274
visceral, 1257
Peritracheo-bronchial glands,
809
Perivascular lymph-spaces, 772
Permanent, teeth, 1206
development of, 1218
eruption of, 1219
superadded, 1218
Peroneal artery, 717
anterior, 717
branches of, 717
peculiarities of, 717
posterior, 718
groove, 248
nerve, 1033
common, 1033
deep, 1033
spine, 246
tubercle, 246
Peroneus brevis muscle, 543
longus muscle, 542
tertius muscle, 537
Perpendicular fasciculus, 962
line of ulna, I '.Ml
plate of ethmo:d bone, 100
of palate bone, 117
Pes anserinus, 1060
of crura cerebri, 905, 910
hippocampi, 947
leonis, 947
Petit, canal of, 1140
triangle of, 437
Petro-mastoid portion of tem-
poral bone, 91
Petro-occipital fissure, 128
suture, 75, 133
Petro-sphenoidal fissure, 128
suture, 136
Petro-squamous sinus, 739
suture, 88
Petro-tympanic fissure, 84, 1162
Petrosal nerve, deep, 1083
great deep, 1049
superficial, 1048
large deep, 1049, 1083
superficial, 1048
process, 93
sinus, inferior, 742
superior, 742
Petrous ganglion, 1066
branches of, 1067
portion of internal carotid
artery, 622
of temporal bone, 136
Peyer's glands, 1304
patches, 1304
Phalanges of foot, 255
articulations of, 255, 361
attachment of muscles of,
255
development of, 255
of hand, 206
articulations of, 206, 327
attachment of muscles, 206
development of, 208
ligaments of, 327
Pharyngeal aponeurosis, 404.
1233
arter}', ascending, 612
branches pf, 612
surgical anatomy of, 612
branch of vagus nerve, 1070
bursa, 1234
glands, 1233
nerve, 1050, 1067
plexus of, 1067
portion of tongue, 1097
region, muscles of, 402
dissection of, 402
ring, lymphatic, 1234
spine, 73, 135
tonsil, 1231, 1234
tubercle, 73
veins, 730
plexus of, 730
Pharyngo-epiglottic fold, 1232
Pharyngo-glossus muscle, 400
Pharynx, 1230
aponeurosis of, 1233
arteries of, 612
fibrous coat of, 1233
isthmus of, 1231
laryngeal part of, 1 232
lymphatic vessels of, 782
mucous coat of, 1233
muscles of, 402
nasal part of, 1231
oral part of, 1231
structure of, 1232
surgical anatomy of, 1234
1598
INDEX
Pharynx, vault of, 1231
Philtriim, 381
Phleboliths, 762
Phrenic arteries, inferior, 682
superior, 646
ganglion, 1092
hernia, 429
nerve, 992
plexus of, 1092
surface of spleen, 1361
veins, 767
Phrenico-costal sinus, 1395, 1422
Phrenico-pleural fascia, 1395
Phreno-colic ligament, 1268
Phreno-pericardial ligament, 561
Physiological retina, 1130
Pia of brain, 980
arteries of, 982
nerves of, 982
veins of, 982
spinal, 859
structure of, 860
Pigmentary layer of retina, 1137
Pileums, 896
Pillars of fauces, 1221
of fornix, 950
Pineal body, 915
gland, 915
Pinna of ear, 1154
arteries of, 1157
cartilage of, 1156
integument of, 1156
ligaments of, 1156
lymphatics of, 1157
muscles of, 1157
nerves of, 1158
structure of , 1156
veins of, 1157
Pisiform bone, 199
articulations of, 199
attachment of muscles to,
199
surfaces of, 199
Pit of stomach, 166
Pituitary body, 917
fossa, 93
membrane, 1110
Pivot-joint, 267
Plane, nuchal, 72
Plantar arch, 719
arteries, external, 719
branches of, 719
surface marking of, 719
surgical anatomy of, 719
internal, 718
branches of, 719
surface marking of, 719
surgical anatomy of, 719
fascia, 545
surgical anatomy of, 546
ligaments, long, 355
superficial, 355
^hort, 355
nerves, external, 1032
internal, 1031
lateral, 1032
medial, 1031
region, muscles of, 547
dissection of, 547
veins, 758
Plantaris muscle, 539
Planum temporale, 76
Plate, cribriform, of ethmoid, 99
horizontal, of palate bone, 116
perpendicular, of ethmoid, 100
of palate bone, 117
pterygoid, external, 96
internal, 96
vertical, of ethmoid, 100
of palate bone, 117
Platysma myoides muscle, 388
Pleurae, 1391
arteries of, 1395
cavity of, 1391
cervical, 1393
costal, 1393
diaphragmatic, 1394
dome of, 1393
lymphatics of, 1395
mediastinal, 1394
nerves of, 1395
parietal layer of, 1393
pericardia!, 1394
pulmonary, 1392
reflections of, 1392
structure of, 1395
surgical anatomy of, 1395
veins of, 1395
visceral layer of, 1391
Pleural lymphatics, 812
sacs, 1246
Pleuroperitoneal cavity, 1246
Plexus, Auerbach's, 1307
choroid of fourth ventricle, 881
interlobular, 1346
of nerves, 826
abdominal aortic, 1089, 1094
adrenal, 1092
annular, 1121
brachial, 994
cardiac, 1090
deep, 1090
great, 1090
superficial, 1090
ventral, 1090
carotid, internal, 1083
cavernous, 1083
cervical, 989
coccygeal, 1034
creliac, 1072, 1094
colic, left, 1095
coronary, 1094
cystic, 1094
dental superior, 1048
dorsal cervical, 984
sacral, 984
epigastric, 1091
fundamental, 1121
gastric, 1094
gastro-duodenal, 1094
gastro-epiploic, 1094
left, 1094
hsemorrhoidal, inferior, 1095
superior, 1095
hepatic, 1094
hypogastric, 1089, 1095
irifraorbital, 1062
intra-epithelial, 1121
lumbar, 1016
lumbo-sacral, 1016
magnus profunda, 1090
mesenteric, inferior, 1094
superior, 1094
cesophageal, 1069, 1072,
1091
ovarian, 1094
pancreatic, 1095
pancreatico-duodenal, 1094
patellar, 1021 .
pelvic, 1095
pharyngeal, 1067
phrenic, 1092
prostatic, 1095
pudendal, 1026
pudic, 1026
pulmonary, 1091
dorsal, 1069, 1072
ventral, 1069, 1072
pyloric, 1094
renal, 1072, 1093
sacral, 1026, 1095
sciatic, 1026
Plexus of nerves, sigmoid, 1095
solar, 1091
spermatic, 1094
splenic, 1072, 1094
subclavian, 10S6
subepithelial, 1121
suprarenal, 1092
thoracic aortic, 1087
tympanic, 1067
uterine, 1095
utero-vaginal, 1095
vaginal, 1095
vertebral, 1086
vesical, 1095
of veins, infraclavicular, 790
palmar, 745
pharyngeal, 730
prostatic, 761
prostatico-vesical, 761
pterygoid, 727
spermatic, 765
spinal, 753
subpleural mediastinal, 646
uterine, 763
vaginal, 763
venous, intraspinal, 732
on thyroid body, 751
vesical, inferior, 762
superior, 761
Plica, epigastrica, 1532
fimbriata, 1097
gubernatrix, 1471
hypogastrica, 1531
salpingopalatine, 1231
salpingopharyngea, 1231
semilunaris, 1150
sublingualis, 1227
triangularis, 1223
urachi, 1531
vascularis, 1471
Pneumatic spaces, 1113
Pneumogastric nerve, 1068
Poles of eye, 1115
Polyaxonic neurones, 823
Polymazia, 1517
Polymorphous nerve cells, ectal,
958
ental, 959
Polythelia, 1518
Pomum Adami, 1370
Pons, 877
basilar groove of, 877
fibres of, longitudinal, 887
transverse, 887
internal structure of, 887
nuclei pontis, 887
Varolii, 877. Sec Pons.
veins of, 736
ventral surface of, 877
Pontal arteries, 641
Ponticulus, 1156
Pontile flexure of brain, 869
Popliteal artery, 707, 708
branches of, 709
peculiarities of, 708
surface marking of, 709
surgical anatomy of, 709
groove, 228
line, 237
lymphatic glands, 794
nerve, external, 1033
internal, 1030
branches, 1031
notch, 236
space, 707
boundaries of, 707
contents of, 708
dissection of, 707
position of contained parts,
708
vein, 758
INDEX
1599
Popliteus muscle, 540
Pore, gustatory, 1100
IWta, 866, 913
Portal sinus, 769
vein, 769
system of, 768
Portio dura of seventh nerve,
1059
ganglia of, 1059
mollis of auditory nerve, 1059
Post -anal gut, 1252
Post-central fissural complex, 930
H-sure, 930
gyro, 931
Poet-glenoid process, 84
Posi-pharyngeal gland, 784
Poetbrachium, 905
P< ist ralrariiie fissure, 926
Postcava, 764
peculiarities of, 764
relations of, 764
surgical anatomy of, 766
Postcerebellar artery, 641
Post cerebral artery, 642
branches of, 642
Postchoroid artery, 642
Postcisterna, 978
Po-t commissure of epiphysis, 915
I 'ost communicant artery, 630
Postcornu, 945
Postdural artery, 612
Posterior auricular artery, 611
nerve, 1062
vein, 727
bicipital ridge, 181
calcaneo-astragaloid ligament,
354
carpal arch, 661
artery of ulnar, 665
cerebral artery, 642
cervical plexus, 987
chondro-stemal ligament, 290
chondro-xiphoid ligament, 290
choroid artery, 642
clinoid process, 93, 132
common ligament, 272
condyloid foramen, 73, 133
136
t'n-sa, 136
costo-transverse ligament, 288
costo-xiphoid ligament, 290
crucial ligament, 339
deep cervical vein, 733
dental canals, 106
divisions of cervical nerves,
986
ethmoidal canal, 82, 100
cells, 101, 145
foramen, 82, 130, 141
sinuses, 101
external jugular vein, 728
extremity of ribs 1(il
head of, 161
neck of, 161
tuberosity of, 162
femoral region, muscles of, 532
fenestrated space, 859
fontanelle, 75, 103
fossa of skull, 132
gluteal line, 216
humeral region, muscles of, 479
inferior cerebellar artery, 641
spinous process of ilium, 217
intercostal veins, 752
internal frontal artery, 629
interosseous artery of ulna, 665
nerve, 1008
intersternal ligament, 292
intertrochanteric line, 225
ligament of incus, 1171
of Winslow, 337
Posterior ligament of wrist, 320
longitudinal ligament, 272
spinal veins, 755
median ganglionic arteries, 642
vein, 736
mediastinal arteries, 668
glands, 808
mediastinum, 1397
medullary velum, '.'ill
meningeal artery, 640
nares, 142, 1108
nasal spine, 116, 135, 143
occipito-atlantal ligament, 278
occipi to-axial ligament, 280
palatine artery, 617
canal, 107, 116
canals, accessory, 116, 135
foramen, 135
nerve, 10 10
parolfactory sulcus, 935
peroneal artery, 718
pillar of soft palate, 1222
pillars of fornix, 950, 951
pubic ligament, 298
radial carpal artery, 661
radio-ulnar ligament, 317
region, muscles of, 488
recurrent tibial artery, 712
root of spinal nerves, 983
sacral foramina, 63
sacral-coccygeal ligament, 296
sacro-iliac ligament, 294
sacro-sciatic ligament, 294
scapular artery, 644
nerve, 999
region, muscles of, 474
semicircular canal, 1167
spinal artery, 641
sterno-clavicular ligament, 3001
sterno-costal ligament, 290
surface of liver, 1337
of stomach, 1278
superior dental nerves, 1047
spinous process of ilium, 216
temporal artery, 613, 642
diploic vein, 734
thoracic nerve, 1000
tibial artery, 715
veins, 758
tibio-fibular region, muscles of, |
537
tibio-tarsal ligament, 349
triangle of neck, 620
tubercle of cervical vertebra, j
50
tympano-malleolar ligament,
" 1166
ulnar recurrent artery, 664
vein, 745
vertebral vein, 733
wall of tympanum, 1162
Postero-lateral fontanelles, 103 j
ganglionic arteries. 642
Postero-median ganglionic arte-;
ries, 630, 642
Post forceps, 940
Postgemina, 905
Postgeniculum, 905
Post hypophysis, 867, 917
Postirisula, 933
Postoblongata, arcuate fibre i
systems of, 886
decussation of lemnisci, 882
gray masses of, 886
internal structure of, 881
pyramidal decussation of, 881
raphe of, 885
rest is of, 885
of Wilder, 874
Postoperculum. 925
Postorbital limbus, 930
Postparietal gyre, 931
Post peduncle of cerebellum, 900
Postperforatum, 908, 916
Postpontile recess, 874
Postramus of cerebellum, 899
Postrhinal fissure, 933
Posttibial nerve, 1031
Postvermis, 896
Pouch, Douglas's, 1502
of Prussak, 1172
recto-vaginal, 1502
utero-vesical, 1499, 1502
Poupart's ligament, 438, 1527
Pre-anal fibres of levator ani, 455
Pre-aortic glands, 798
Pre-auricular lymphatic glands,
779
Pre-oblongata, 878
fibre-tracks in, 888
gray masses in, 888
internal structure of, 887
nucleus incertus, 888
superior olivary nucleus, 887
Pre-occipital notch, 922
Pre-operculum, 925
Pre-sternal notch, 157
Pre-sternum, 157
Prebrachium, 905
Precava, 752
relations of, 752
surgical anatomy of, 753
Precentral fissure, 927
superior, 927
gyre, 929
Precerebellar artery, 642
Precerebral artery, 628
branches of, 628
Prechoroid artery, 630
Precommissure, 952
Precommunicant artery, 628, 629
Precornu, 943
Precuneal fissure, 931
Predural artery, 623
Preforceps, 940
Pregemina, 905
Pregeniculum, 913, 914
Prehypophysis, 917
Preinsula, 933
gyres, 933
Prelaryngeal glands, 785
Premaxillary bones, 110
Prepatellar bursa, 342, 521
Prepeduncles, 879
cerebellar, 888, 901, 909
Preperforation, 867, 935
Prepuce of clitoris, 1494
of penis, 1465
Prepyramidal tract of cord, 853
Preramus of cerebellum, 899
Pressure curves of humerus, 183
Presylviari ramus, 924
Pretracheal fascia, 391
glands, 786
Prevermis, 896
Prevertebral fascia, 390
Prickle cells, 1119
Primordial ova, 1514
Princeps hallucis artery, 715
pollicis artery, 662
Pro-gnathous skull, index of, 148
Pro-otic portion of temporal
bone, 91
Process or processes, acromion,
175
alveolar, 140
angular, 80
external, 14O
internal, 140
of atlas, 55
auditory, 88
basilar, 73
1600.
IXDEX
Process or processes, of calca-
neus, greater, 245
lesser, 245
clinoid, anterior, 131
middle, 93, 132
posterior, 93, 132
cochleariform, 91, 1163
condyloid of lower jaw, 125
coracoid, 176
coronoid, of jaw, 125
of ulna, 188
costal, 50
ethmoidal, of inferior turbin-
ated, 120
falciform, 517
hamular, of lachrymal, 1 13
of sphenoid, 90
of inferior turbinated bone, 120
of Ingrassias, 96
jugular, 73
lachrymal, of inferior turbin-
ated, 120
of malar bone, 114
mammillary, of lumbar verte-
brae, 57
mastoid, 86, 138
mental, 122, 140
nasal, 80
odontoid, of axis, 52
olecranon, 186
olivary, 93, 131
orbital, 118
of malar, 114
of palate bone, 118
petrosal, 93
postglenoid, 84
pterygoid, of palate bone, 117
of sphenoid bone, 96
sphenoidal, 1107
of palate bone, 118
spinous, of ilium, 217
of sphenoid, 95
of tibia, 236
stylohyal, 92
styloid, of fibula, 239
of temporal bone, 90
of ulna, 191
of superior maxillary, 109, 110
tympanohyal, 92
unciform, 202
of ethmoid, 100
vaginal, of sphenoid, 95
of temporal bone, 90
of vertebra, articular, 49
zygomatic, 84
Processus brevis of malleus, 1 1 69
cochleariformis, 91, 1163
gracilis of malleus, 1 168
tubarius, 1165
vaginalis, 1471
Proctodseum, 1252
Profunda artery, inferior, 658
superior, 657
femoris artery, 704
vein, 759
Projection fibres of cerebrum,
963
Prominentia styloide*, 1163
Promontory of sacrum, 61
of tympanum, 1162
Pronator quadratus muscle, 485
radii teres muscle, 481
surgical anatomy of,
481
ridge, 190
Prosencephalon, 91 1
Prostate gland, 1457
apex of, 1461
arteries of, 1462
base of, 1461
capsule of, 1459
Prostate gland, isthmus of, 1461
lobes of, 1461
lymphatic vessels of, 800
lymphatics of, 1462
nerves of, 1462
sheath of, 1459
structure of, 1462
surfaces of, 1461
surgical anatomy of, 1462
veins of, 1462
Prostatic ducts, orifices of, 1451
plexus of nerves, 1095
of veins, 761
portion of rectum, 1321
of urethra, 1450
secretion, 1462
sinus, 1451
vesicle, 1451
Prostatico-vesical plexus,' 761
surgical anatomy of, 762
Proton, 869
Proto vertebra, 1245
Protuberance, mental, 122
occipital, external, 71, 136
internal, 73
Prbtuberantia annularis, 877
Prussak, pouch of, 1172
Psalterium, 951
Pseudocele, 920, 921, 941
Pseudostomata, 1256
Psoas magnus muscle, 512
parvus muscle, 512
Pterion, 137, 150
ossicle, 83, 103
Pterygoid artery, 616
canal, 135
depression, 125
fissure, 96
fossa of jaw, 115
of sphenoid, 96
muscles, external, 386
internal, 386
nerve, external, 1051
internal, 1051
notch, 96
plate, external, 96
internal, 96
plexus of veins, 727
process of palate bone, 117
of sphenoid bone, 96
ridge, 95, 137
tubercle, 97
Pterygo-mandibular ligament,
383
region, dissection of, 385
muscles of, 385
nerves of, 387
Pterygo-maxillary fissure, 139
ligament, 383
Pterygo-palatine artery, 617
canals, 135
fossa, 139
groove, 116
nerve, 1050
Pubic arch, 211
ligament, anterior, 298
inferior, 298
posterior, 298
superior, 298
portion of fascia lata, 1540
surface of bladder, 1442
Pubis, 219
angle of, 219
body of, 219
ramus of, ascending, 219
descending, 220
inferior, 220
superior, 219
spine of, 219
Pubo-capsular ligament, 330
Pubo-coccygeus muscle, 454
Pubo-femoral ligament, 330
Pubo-prostatic ligament, 1445,
1461
Pubo-vesical ligament, 1445
muscle, 1446
Pudendal nerve, inferior, 1028
plexus of, 1026
slit, 1489
Pudendum, 1489
Pudic artery, accessory, 691
external deep, 704
superficial, 704
internal, in female, 693
in male, 690
branches of, 691
peculiarities of, 691
surgical anatomy of, 691
nerve, 1028
plexus of, 1026
vein, internal, 760
Pulmonary alveoli, 1386
artery, 589
left, 589
opening of, 571
right of, 589
branches of thoracic portion
of gangliated cord, 1087
lymphatics, 812
nerves, dorsal, 1072
ventral, 1072
pleura, 1392
plexus, 1091
dorsal, 1069, 1072, 1091
ventral, 1069, 1072, 1091
sinuses of Valsalva, 573
veins, 723
Pulmonic semilunar valves, 573
Pulp, dental, 1210
Pulvinar of optic thalamus, 913
Puncta lacrimalia, 1152
Punctum lacrimale, 1148
Pupil of eye, 1127
Pupillary margin, 1127
Purkinje, cells of, 902
fibres of, 577
Putamen, 954
Pyloric artery, inferior, 675
superior, 675
glands, 1285
orifice of stomach, 1279
plexus, 1094
portion of stomach, 1277
sphincter, 1280
valve, 1280
Pylorus, 1279
antrum of, 1279
Pyramid of Ferrein, 1425
of Lalouette, 1411
of Malpighi, 1425
of oblongata, 875
decussation of, 875
of tympanum, 1163
of vestibule of ear, 1174
Pyramidal lobe of cerebellum,
898
nerve cells, 958
tract, 956
crossed, 853
of crusta, 910
direct, 854
Pyramidalis muscle, 446
nasi muscle, 378
Pyramido-oliviary groove, 876
Pyriformis muscle, 527
bursa of, 528
QUADRATE lobe of liver, 1340
Quadratus femoris muscle, 530
IXDKX
1601
Quadratus hunhorum, fascia of,
451
muscle, 451
mrnti muscle, 380
Quadriceps extensor muscle, 518
Quudrigemina, 869, 005, 907
brachia of, 905
nates of, 905
postgemina of, 905, 907
pregemina of, 905, 907
structure of, 905
testes of, 905
Quadrilateral muscles, 365
RADIAL artery, 659
branches of, 661
peculiarities of, 660
relations of, 659
surface marking of, 660
surgical anatomy of, 660
fossa, 183
head of humerus, 183
nerve, 1008
recurrent artery, 661
region, muscles of, 486, 497
dissection of, 486
vein. 745
Radialis indicis artery, 662
Radiate fissure, 928
Radio-carpal articulations, 319
surface form of, 320
surgical anatomy of, 320
Radio-ulnar articulation, 315
inferior, 317
surface form of, 319
middle, 316
superior, 316
surface form of, 316
surgical anatomy of, 316
ligaments, annular, 316
anterior, 317
oblique, 316
orbicular, 316
posterior, 317
round, 316
region, anterior, muscles of, 481
surgical anatomy of, 486
posterior muscles of, 488
surgical anatomy of, 493
Radius, 192
articulations of, 194
attachment of muscles to, 19-1
development of, 194
lower extremity of, 193
shaft of, 192
borders of, 192, 193
surfaces of, 193
sigmoid cavity of, 193
structure of, 194
surface form of, 194
surgical anatomy of, 194
upper extremity of, 192
Rami of lower jaw, 124
Ramus episylvian, 925
hyposylvian, 925
of isehimn, ascending, 218
descending, 218
presylvian, 924
of pubis, ascending, 219
descending, 220
inferior, 220
superior, 219
subsylvian, 924
Ranine artery, 606
vein, 729
Raph6 of perineum, 1549
of poetoblongata, 885
of scrotum, 1473
101
Raph6 of tongue, 1097
Receptaculum chyli, 775
Recess, epitympanic, 87
infundibular of third ventricle,
917
postpontile, 874
Recessus cochlearis of Reichert.
1174
tecti, 902
Reciprocal reception, articula-
tion by, 267
Rectal columns, 1326
glands, snr,
valves, 1326
Recto-urethralis muscle, 456
Recto-uterinus muscle, 1503
Recto-vaginal fold, 1502
pouch, 1322, 1502
Recto-vesical fascia, 1558
pouch, 1322
Rectum. 1320
areolar coat of, 1325
arteries of, 1327
curves of, 1321
lymphatics of, 807, 1329
mucous membrane of, 1326
muscular coat of, 1324
nerves of, 1329
prostatic portion of, 1321
sacrococcygeal portion of, 1320
serous coat of, 1324
structure of, 1324
submucous coat of, 1325
supports of, 1322
surface form of, 1331
surgical anatomy of, 1331
veins of, 1328
Rectus abdominis muscle, 444
capitis anticus major muscle.
408
minor muscle, 409
lateralis muscle, 409
posticus major muscle. 424
minor muscle, 424
femoris muscle, 518
oculi muscle, external, 375
inferior, 375
internal, 375
superior, 375
Recurrent artery, palmar, 662
radial, 661
tibial, anterior, 713
posterior, 712
ulnar, anterior, 664
posterior, 664
laryngeal nerve, 1071
Reflections of pleurae, 1392
Refracting media of eye, 1138
Reichert, recessus cochlearis of,
1174
Reil, island of, 933
Reissner, membrane of, 1182
Renal artery, 680
inferior, 1432
bloodvessels, 1432
impression of liver, 1337
plexus, 1072, 1093
surface of spleen, 1361
veins, 767
zone of Hyrtl, exsanguinated,
1432
Reservoir of Pecquet, 775
Respiration, muscles of, 433
organs of, 1369
Respiratory nerve of Bell, exter-
nal, 1000
internal, 992
Rest is of oblongata, 876
of postoblongata, 885
HHe test is of Haller, 1482
Reticular formation of cord, 845
Retina, 1130
nerve-fibres of, 1 1 32
physiological, 1130
pigmentary layer of , 1137
rods of, 1135
structure of, 1131
supporting framework of, 1137
Retinacula of capsular ligament
of hip, 329
patellae mediale, 520
Retrahens auriculam muscle, 371
Retro-aortic glands, 797
Retro-csecal fossa, 1272
Retro-colic fossa>, 1272
Retro-crural glands, 795
Retro-duodenal fossa, 1271
Retro-peritoneal lossa?, 1270
space, 1257
Retro-pharyngeal glands, 784
space, 391, 1230
Retro-rectal space, 1322
Retro-renal fascia, 1420
Retro-sternal glands, 807
Retzius, brown striae of, 1214
fundiform ligament of, 544
gyrus fasciolaris of, 938
intralimbicus of, 937
space of, 1 442
Rhinencephalon, 920, 934
central part of, 936
cortical part, of, 936
Rhodopsin, or visual purple, 1130
Rhombencephalon, 874
Rhombocaele, 845
Rhomboid impression, 170
ligament, 300
Rhomboidal muscles, 365
Rhomboideus major muscle, 416
minor muscle, 416
Rlbes, ganglion of, 1077
Ribs, 163
anterior extremity of, 162
articulations of, 285
attachment of muscles to, 165
cervical, 53, 167
common characters of, 161
development of, 165
false, 161
floating, 161
peculiar, 163
posterior extremity of, 161
shaft of, 162
structure of, 165
true, 161
Ridges, bicipital, 181
epicondylic, 181
gluteal, 226
mylo-hyoid, 123
naso-labial, 380
. oblique, of trapezium, 200
of ulna, 190
pectoral, 181
pronator, 190
pterygoid, 95, 137
superciliary, 80
supracpndylar, external, 181
internal, 181
supraorbital, 140
temporal, 76, 80
trapezoid, 169
Riedel's lobe of liver, 1343
Right ascending lumbar vein,
752
azygos vein, 752
bronchus, 1384
cardiac vein, 771
colic artery, 677
coronary artery, 592
plexus, 1090
forechamber of heart, 567
innominate vein. 750
1602
INDEX
Right juxta-aortic glands, 797
lobe of liver, 1340
lymphatic duct, 777
superior intercostal vein, 752
Rima glottidis, 1377
Ring, abdominal, internal, 448
crural, 439, 1544
femoral, 439, 511, 1544
fibrous, of heart, 576
muscle of Miiller, 1126
Ripa, 912
Risorius muscle, 383
Risus sardonicus, 383
Rivinus, ducts of, 1227
notch of, 1161
Rod-bipolars, 1135
Rod-cells, 1136
Rod-fibre, 1136
Rod-granules, 1135
Rods of Corti, 1184
of retina, 1135
Rolandic angle, 926
Rolando, fissure of, 926
Roots of cervical nerves, 986
of fifth nerve, ascending, 1042
descending, 1042
•of lumbar nerve, 1015
of lung, 1402
of penis, 1464
of sacral nerves, 1023
of spinal nerves, 983
dorsal, 983
ventral, 983
of thoracic nerves, 1010
of tongue, 1097
of vagus nerve, ganglion of,
1069
Rosenmuller, fossa of, 1231
gland of, 794
accessory, 1151
organ of, 1511
Rostral fissure, 928
Rostrum, 920
of sphenoid bone, 94, 135
Rotary joint, 287
Rotatores spinsc muscle, 423
Round ligament, artery of, 689
of liver, 1342
of uterus, 1503
Roux's amputation of foot, 259
Rubro-spinal tract of cord, 853
Rudimentary organ of Jacobson,
1110
Rudinger, dilator tubse muscle
of, 1165
Rugse of scrotum, 1473
of stomach, 1283
of vagina, 1496
Ruysch, tunic of, 1123
S
SACS, abdominal, 1246
dental, 1216
lachrymal, 1152
pericardia!, 1246
pleural, 1246
Saccule of "vestibule, 1180
Sacculi alveolares, 1386
Sacculus laryngis, 1379
Sacral artery, lateral, 694
middle," 683
canal, 64
cornua, 62
foramina, anterior, 62
posterior, 63
groove, 63
lymphatic glands, 797
nerve. 1023
Sacral nerve, division of, dorsa
1023
ventral, 1025
roots of, 1023
plexus, 1026, 1095
portion of gangliated rord
1089
veins lateral, 760
middle, 764
Sacro-coccygeal ligament, ant
rior, 296
lateral, 297
posterior, 296
portion of rectum, 1320
symphisis, 66
Sacro-iliac ligament, anterior, 294
interosseous, 294
long, 294
oblique, 294
posterior, 294
short, 294
Sacro-lumbalis muscle, 421
Sacro-sciatic foramen, great, 218,
296
inferior, 296
lesser, 218, 296
superior, 296
ligament, anterior, 295
great, 294
lesser, 295
posterior, 294
notches, 211
great, 217
lesser, 218
Sacro-uterine ligaments, 1502
Sacro- vertebral angle, 61
Sacrum, 61
ala of, 64
apex of, 64
articulations of, 65
attachment of muscles to, 65
base of, 64
development of, 64
differences in the male and
female, 64
peculiarities of, 64
promontory of, 61
structure of, 64
surfaces of, 61
tuberosity of, 63
Saddle-joint, 267
Sagittal axis, 1115
sulcus, 73, 80
suture, 78, 127
Salivary glands, 1224
structure of, 1227
surgical anatomy of, 1234
Salpingo-palatine fold, 1231
Salpingo-pharyngeal fold, 1231
Salpingo-pharyngeus muscle, 40"
Salter, incremental lines o!
1213
Santorini, cartilages of, 1373
comical tubercle of, 1376
fissures of, 1156, 1158
muscle of, 383
Saphenous gland, external, 794
opening, 516, 1541
nerve, 1022
external, 1031
internal, 1022
long, 1022
short, 1031
vein, external, 756
internal, 756
long, 756
short, 756
surgical anatomy of, 757
Sarcolemma, 364
Sardonic laugh, 383
Sartorius muscle, 518
Sartorius muscle, nerve to, 1022
St-ala media, 1182
tympani of cochlea, 1178
vestibuli of cochlea, 1178
Scalenus muscles, anticus, 410
medius, 410
posticus, 411
Scalp, skin of, 368
Scapha, fossa of, 1155
Scaphoid bone of foot, 249
articulations of, 249
attachment of muscles to,
249
surfaces of, 249
tuberosity of, 249
of hand, 197
articulations of, 198
attachment of muscles to,
198
surfaces of, 198
fossa, 97, 135, 1154
skull, 146
Scapula, 172
angles of, 175
articulations of, 178
attachment of muscles to, 178
base of, 176
borders of, 175. 176
development of, 177
dorsum of, 173
head of, 176
ligaments of, 303
spine of, 175
structure of, 177
surface form of, 178
surgical anatomy of, 178
venter of, 172
Scapular arteries, posterior, 644
glands, 788
nerve, posterior, 999
notch, great, 175
region, anterior, muscles of,
473
dissection of, 473
posterior, muscles of, 474
dissection of, 474
Scapulo-clavicular articulation,
301
Scarf skin, 1191
Scarpa, fascia of, 435
foramina of, 110, 135, 1050
ganglion of, 1065
membrane of, 1162
nerve of, 1050
triangle of, 518, 698
Schachowa, spiral tube of, 1427
Schindylesis, 266
Schlemm, canal of, 1118, 1121
ligament, 307
Schmidt-Lautermann, incisures
of, 824
Schneiderian membrane, 1110
Schreger, concentric lines of, 1213
Schultze, comma tract of, 851
Schwann, medullary sheath of,
824
Sciatic artery, 693
nerve, great, 1030
branches of, 1030
small, 1027
branches of, 1028
notch, great, 217
plexus, 1026
veins, 761
Sclera, 1117
structure of, 1118
Scleral sulcus, 1115
Sclerotic coat, 1117
Scrotal hernia, 1533
nerve, long, 1028
Scrotum, 1472
Scrotum, arteries of, 1476
dartos of, 1473
integument of, 1473
lymphatic vessels of, 799
lymphatics of, 1470
nerves of, 1476
raphe of, 1473
rugae of, 1473
septum of, 1473
surgical anatomy of, 1478
veins of, 1476
Sebaceous glands, 1148, 1201
Second nerve, 1038
Secondary ear-drum membrane
1162
Sella turcica, 93, 131
Semen, 1485
Semicircular canals, 1175
external, 1175
horizontal, 1175
membranous, 1180
posterior, 1175
superior, 1175
muscles of rectum, 1325
Semilunar bone, 198
articulations of, 199
surfaces of, 198
fascia, 478
nbro-cartilages, 339
external, 341
internal, 340
folds of colon, 1325
of Douglas, 441, 446
ganglion of abdomen, 1091
of fifth nerve, 1042
hiatus, 145, 747
valves, aortic, 574
pulmonic, 573
."Semimembranosus muscle, 533
bursa of, 534
Seminal duct, 1484
vesicles, 1486
arteries of, 1487
lymphatic vessels of, 802
lymphatics of, 1487
nerves of, 1487
structure of, 1487
surgical anatomy of, 1487
veins of, 1487
'Semispirialis colli muscle, 423
dorsi muscle, 423
Semitendinosus muscle, 533
Sensor neurones, 816
peripheral axone of, 819
root of spinal cord, 836
Septum atriorum, 569
crurale, 1544
of Cloquet, 511
interauricular, 567
intervenrioular, 751
lucidum, 941,952
of nose, 142
cartilage of, triangular, 1107
orbital, 1149
pectiniforme, 1467
pellucidum, 921
of scrotum, 1473
of tongue, fibrous, 400
transversum, 1180
Serous coat of anal canal, 1324
of bladder, 1446
of, gall-bladder, 1351
of large intestine, 1324
of lungs, 1362
of rectum, 1324
of small intestine, 1298
of spleen, 1363
of stomach, 1281
of vermiform appendix,
1312
•covering of ovary, 1513
INDEX
Serous pericardium, 562
Sorratus inagnus muscle, 471
posticus inferior muscle, 417
superior muscle, 417
Sertoli, cell of, 1483
Sesamoid bones, 259
cartilage, 1107
Seventh nerve, 1059
surgical anatomy of, 1004
Shaft of bone, its structure, 33
of hair, 1199
of ribs, 162
Sharpey, fibres of, 37
Sheath, carotid, 390
dentinal, of Neumann, 1213
femoral, 511, 1542
of flexor tendons, fibrous, 548
granular, of Tomes, 1212
myelin, 824
of prostate, 1459
of rectus muscles, 445
synovial, 265
Shin bone, 234
Short bones, 33
calcaneo-cuboid ligament, 355
ciliary arteries, 627
plantar ligament, 355
sacro-iliac ligament, 294
saphenous vein, 756
Shoulder, fascia of, deep, 472
superficial, 472
girdle, 168
muscles of, 472
Shoulder-joint, articulations of,
305
bursse of, 307
surface form of, 309
surgical anatomy of, 309
Shrapnell, membrana flaccida of,
1166
Sibson, aortic vestibule of, 574
aponeurosis, 1393
Sigmoid arteries, 680
cavity of radius, 193
of ulna, 186
colon, 1317
flexure of colon, 1317
of large intestine, 1308
fossa, 86
rnesocolon, 1269
notch of lower jaw, 125
plexus, 1095
sinus, 739
sulcus, 86
Sinus or sinuses, air, 82
alse parvsc, 740
of aorta, great, 591
basilar, 743
cavernous, 739
circular, 742
confluence of, 737
coronary vein, 569, 771
costo-mediastinal, 1395
of dura, 736
ethmoidal, 101
falcial, 738
frontal, 80
of heart, auricle of, left, 570
right, 567
intercavernous, 742
of jugular vein, external, 728
internal, 729
ot kidney, 1423
laryngeal, 1379
lateral, 738
longitudinal, inferior, 738
superior, 78, 130, 736
maxillary, 108
of Morgagni, 404
of nose, 80
occipital, 739
1603
Sinus or sinuses, orbital, 118
of pericardium, oblique, 562
transverse, 562
petrosal, inferior, 742
superior, 742
petro-squamous, 739
phrenico-costal, 1395, 1422
pocularis, 1451
portal, 769
prostatic, 1451
pyriformis, 1232, 1376
sigmoid, 739
spheno-parietal, 740
sphenoidal, 94, 143
straight, 738
subpetrosal, 742
superpetrosal, 742
tentorial, 738
terminalis, 845
tonsillaris, 1232
transverse, 743
peric»rdial, 562
utricularis sacculi, 1180
of Valsalva, aortic, 575
pulmonary, 573
venosus, 567
Sixth nerve, 1057
surgical anatomy of, 1058
Skeletal muscles, 363
Skin, 1188
appendages of, 1195
arteries of, 1194
cuticle of, 1191
epidermis, 1191
folds of, 1188
furrows, 1189
horny layer of, 1191
lymphatics of, 1194
Malpighian layer of, 1192
nerves of, 1194
papillary layer of, 1191
pigmentation of, 1192
ridges, 1189
of scalp, 368
scarf, 1191
stratum cylindricum, 1192
germinativum, 1192
granulosum, 1192
lucidum, 1192
mucosum, 1192
spinosum, 1192
true, 1190
veins of, 1 1 94
Skull, acrocephalic, 146
angles of, 147
anterior region of, 139
base of, 130
brachycephalic, 146
at different ages, 102
dimensions of, 147
dolichocephalic, 146
fixed point for measurement of,
150
fossa of, anterior, 130
infratemporal, 138
middle, 130
orbital, 140
posterior, 132
pterygo-palatine, 139
spheno-maxillary, 139
temporal, 137
zygomatic, 138
index of, 147
cephalic, 147
facial, 147
gnathic, 148
of height, 147
mesognathous, 148
nasal, 147
orbital, 147
ortho-gnathous, 148
1604
INDEX
Skull, index of, palatal, 147
prognathous, 148
lateral regions of, 136
megacephalic capacity of, 147
mesocephalic capacity of, 147
microcephalic capacity of, 147
scaphoid, 146
sexual differences in, 102
shape of, 146
surface form of, 148
surgical anatomy of, 150
tables of, 33
vitreous, 34
vertex of, 129
Small coronary vein, 771
intestine, 1290
occipital nerve, 989
palatine nerve, 1050
sciatic nerve, 1027
Smell-brain, 920
Socia parotidis, 1225
Soft palate, 1221
aponeurosis of, 1222
arches of, 1221
arteries of, 1222
mucous membrane of, 1222
muscles of, 1222
nerves of, 1223
pillars of, 1221
veins of, 1223
Solar plexus, 1091
Soleus muscle, 538
Solitary glands, 1303, 1327
Somatopleure, 1245
Sommerring, foramen of, 1131
yellow spot of, 1131
Space or spaces, axillary, 647
of Burns, 389
cartilage, 262
corneal, 1120
epidural, 857, 973
epitympanic, 87
fenestralia, 859
of Fontana, 1120
intercostal, 161
intercrural, 904
interglobular, of Czermak,
1212
interpleural, 1396
mediastinal, 1396
of Nuel, 1185
perichoroidal, 1118
perisclerotic, 1113
pneumatic, 1113
popliteal, 707
retro-peritoneal, 1257
retro-pharyngeal, 391, 1230
of Retzius, 1442
subarachnoid, 858, 977
anterior, 978
subdural, 858, 973
suprascleral, 1113
suprasternal, 389
Special sense, organs of, 1097
Spermatic arteries, 681
canal, 450, 1529
cord, 1476
arteries of, 1477
lymphatics of, 1478
nerves of, 1478
structure of, 1476
surgical anatomy of, 1478
veins of, 1477
fascia, 1464
external, 1526
internal, 448
middle, 442
nerve, external, 1018
plexus of, 1094
vein, 765 .
plexus of, 765
Spermatic vein, surgical anatomv
of, 766
Spermatids, 1483
Spermatoblasts, 1483
Spermatocysts, 1483
Spermatogenesis, 1483
Spermatogonia, 1483
Spermatozoid, 1483
Spheno-ethmoidal recess, 145
Spheno-maxillary fissure, 115
138
fossa, 115, 139
Spheno-palatine artery, 617
foramen, 119, 143
ganglion, 1048
nerves, 1047
notch, 118
Spheno-parietal sinus, 740
suture, 128
Spheno-phrenic ligament, 1266
Sphenoid bone, 92
articulations of, 98
attachment of muscles to
98
body of, 92
surfaces of, 93
development of, 97
greater wings of, 95
circumference of, 95
surfaces of, 95
hamular process of, 96
lesser wings of, 96
pterygoid process of, 96
rostrum of, 94, 135
Sphenoidal cells, 94
crest, 94
fissure, 96, 132
process, 1107
of palate bone, 118
sinuses, 94, 143
spine, 95
spongy bones, 97
turbinated bones, 143
Spherical recess, 1174
Sphincter ani muscle, external,
452
internal, 453
muscles, 365
pyloris, 1280
vaginae muscle, 463
Spigelian lobe of liver, 1337
Spina tympanica major, 1161
minor, 1161
Spinal accessory nerve, 1073.
See Accessory nerve,
arachnoid, 858
arteries, anterior, 640
dorsal, 641
lateral, 640
posterior, 641
ventral, 640
branch of vertebral artery, 640
bulb, 874
canal, 69
column, 48
cord, 834
arachnoid, 858
axones of, myelinization of,
855
canal of, central, 845
cells of, 855
columns of, 839
dorsal, ground bundle of,
852
lateral, ground bundles of,
853
ventral, ground bundles
of, 854
commissure of, 844, 845
white, ventral, 854
conus of, 837
Spinal cord, cornua of, dorsal
horn, 844
lateral horn, 845
•ventral horn, 845
development of, 840
dissection of, 856
dura of, 856
enlargement of, 836
cervical, 836
lumbar, 836
external morphology of, 835
fibres, longitudinal, 848
filum of, 837
fissures of, 837
gliosa of, 847
grooves of, 837
ground bundles of, 849
internal structure of, 843'
membranes of, 856
muscular supply from motor
segments of, 843
pia of, 859
reticular formation of, 845
roots of, 836
afferent, 836
dorsal, 836
efferent, 836
motor, 836
sensor, 836
ventral, 836
substances of, gray, 843, 855
white, 848, 856'
surgical anatomy of, 860
tracts of, cerebello-spinal,
853
conducting, 841
direct cerebellar, 852
dorso-lateral spino-cere-
bellar, 852 •
functions of, 844
intermedio-lateral, 853
lateral vestibulo-spinal,
853
marginal, 851
olivo-spinal, 853
prepyramidal, 853
pyramidal, 853
direct, 854
rubro-spinal, 853
spino-mesencephalic, 852
spino-olivary, 853
spino-thalamic., 852
sulco-marginal, 854
superficial ventro-lateral
spino-cerebellar, 852
ventral cerebello-spinal,
854
vestibulo-spinal, 854
veins of, 755
ventral column of, ground
bundle of, 854
weight of, 835
dura, 856
foramen, 49
nerves, 982
accessory, 1073
distribution of, 984
ganglia of, 983
gray ramus communicans of,
985
points of emergence of, 985
roots of, dorsal, 982
ventral, 982
visceral branches of, 985
white ramus communicans
of, 985
portion of accessory nerve, 1074
veins, 753
longitudinal, anterior, 754
posterior, 755
plexus of, 753
1M)EX
1605
Spinalis colli muscle, 422
dorsi muscle, 421
Spindle, aortic, 593
Spindles, neuro-muscular, 830
neuro-tendinous, 831
Spine, articulations of, 278
ethmoidal, 93, 130
frontal, 80
of helix, 1156
of Henle, 88
of ilium, 217
of ischium, 218
mental, 123
nasal, SO
anterior, 111, 139, 143
posterior, 116, 135, 143
palatine, 116
peroneal, 246
pharyngeal, 73, 135
progress of ossification in, 60
of pubis, 219
of scapula, 175
spheiioidal, 95
suprameatal, 88
Spino-cerebellar tract, ventral,
901
Spino-glenoid ligament, 304
Spino-mesencephalic tract of
cord, 852
Spino-olivary tract, 853, 886
Spino-thalamic tract of cord, 852
Spinous processes of ilium, 217
of tibia, 236
of vertebrae, 49
Spiral canal of cochlea, 1177
ligament of cochlea, 1182
line of femur, 225
tube of Schachowa, 1427
Spitzka, marginal tract of, 852
Splanchnic nerves, 1087
Splanchnopleure, 1245
Spleen, 1361
accessory, 1363
arteries of, 1364
development of, 1255
fibre-elastic coat of, 1363
hilum of, 1361
lymphatics of, 804, 1366
Malpighian bodies of, 1365
movability of, 1363
movable, 1363
nerves of, 1366
serous coat of, 1363
.structure of, 1363
supernumerary, 1363
support of, 1363
surface form of, 1366
surgical anatomy of, 1366
veins of, 1366
Splenic artery, 676
flexure of colon, 1317
of large intestine, 1308
glands, 798
plexus, 1072, 1094
pulp, 1363
vein, 768
Splenium, 920, 940, 941
Splenius muscle, 418
Spongioblasts, 818
Spongiosa, 847
Spongy portion of urethra, 1452
tissue of bone, 33
Spur, femoral, 229
Squamo-parietnl suture, 128
Squamo-sphenoidal suture, 128
Squamous portion of occipital
bone, 71
suture, 85, 128
Square lobe of liver, 1340
Stahr, middle fdand of, 784
Stapedius muscle, 1171
Stapes, 1170
base of, 1170
crura of, 1170
foot-plate, 1170
head of, 1170
ligament of, 1171
neck of, 1170
Statoliths, 1181
Stellate cells, 821
ligament, 286
reticulum, 1216
Stenson, duct of, 1225
foramina of, 110
Stephanion, 137
inferior, 76, 150
superior, 76, 150
Sternal arteries, 646
foramen, 159
furrow, 166
glands, 807
ribs, 161
Sterno-clavicular articulations,
299
surface form of, 301
surgical anatomy of, 301
Sterno-cleido-mastoid muscle,391
Sterno-costal ligament, anterior,
290
interarticular, 290
posterior, 290
Sterno-costo pericardial ligament,
560
Sterno-hyoid muscle, 394
Sterno-mastoid artery, 605, 611
glands, 785
muscle, 391
surface form of, 393
surgical anatomy of, 393
Sterno-pericardiac ligaments, 560
Sterno-thyroid muscle, 394
Sternum, 157
angle of, 157
articulations of, 161, 292
attachment of muscles to, 161
development of, 159
ensiform appendix of, 159
gladiolus, 157
ligaments of, 292
manubrium of, 157
structure of, 159
surface form of, 166
surgical anatomy of, 167
xiphoid appendix of, 159
Stigmata, 1256
Stilling, canal of, 1139
nucleus of, 847
Stomach, 1277
alterations in position of, 1280
areolar coat of, 1283
arteries of, 1286
body of, 1277
cardiac orifice of, 1278
portion of, 1277
chamber, 1277
curvatures of, 1278
fundus of, 1277
innervation of, 1288
lymphatic vessels of, 804, 1287
movements of, 1288
mucous membrane of, 1283
muscular coat of, 1282
nerves of, 1287
oesophageal opening of, 1278
peritoneal coat of, 1281
pit of, 166
pyloric orifice of, 1279
portion of, 1277
relations of, 1277
rugae of, 1283
serous coat of, 1281
structure of, 1281
Stomach, submucous coat of,
1283
supports of, 1281
surface form of, 1288
surfaces of, 1277
surgical anatomy of, 1288
vascular coat of, 1283
veins of, 1287
Stomach teeth, 1207
Stomata, 1256
Straight sinus, 738
Stratum cinereum, 907
opticum, 907
zonale, 907, 912
Stria medullaris, 912
terminalis, 913
vascularis, 1182
Striae, olfactory, 935
Striated muscle, 363
structure of, 364
Striatum, 952
connections of, 964
Striped muscle, 363
Stroma of iris, 1128
of ovary, 1514
plexus of, 1121
Stylo-glossus muscle, 399
Stylo-hyal process, 92
Stylo-hyoid ligament, 397
muscle, 396
nerve from facial, 1062
Stylo-mandibular ligament, 283,
389
Stylo-mastoid artery, 611
foramen, 90, 135
Stylo-maxillary ligament, 283
Stylo-pharyngeus muscle, 405
Styloid process of fibula, 239
of temporal bone, 90
of ulna, 191
Subacromial bursa, 307, 473
Subanconeus muscle, 480
Subarachnoid cisternae, 978
space, 859, 977
anterior, 978
tissue, 859
Subarachnoidean areolar tissue,
977
Subcalcarine gyre, 932
Subcallosal gyre, 867
Subcerebellar veins, 736
Subcerebral veins, 735
Subclavian artery, 633
branches of, 639
first part of left, 635
right, 633
peculiarities of, 636
second part of, 635
surface form of, 637
surgical anatomy of, 637
third part of, 636
glands, 790
groove, 170
loop, 1086
plexus of nerves, 1086
triangle, 620
vein, 749
Subclavius muscle, 470
Subcollateral gyre, 932
Subcostal artery, 669
groove, 163
Subcrureus muscle, 521
Subcutaneous acromial bursa,
307
areolar tissue, 1190
olecranon bursa, 479
synovial bursa, 265
tibial bursa, 342
trochanteric bursa, 333
Subdnltoid bursa, 307, 473
Subdural space, 858, 973
1606
INDEX
Subepithelial plexus, 1121
Subfrontal fissure, 927
gyre, 929
Sublingual artery, 606
fossa, 123
gland, 1227
Sublobular veins, 767
Submaxillary artery, 608
fossa, 123
ganglion, 1054
branches of, 1054
gland, 784, 1226
arteries of, 1227
ducts of, 1226
lymphatics of, 1227
nerves of, 1227
veins of, 1227
triangle, 396, 619
vein, 727
Submental artery, 608
glands, 784
Subnasal point of skull, 150
Suboccipital fissure, 931
lymphatic glands, 779
nerves, 986
triangle, 425
Suboperculum, 925
Suborbital glands, 781
Subparotid glands, 1225
lymphatic glands, 781
Subpetrosal sinus, 742
Subpleural mediastinal plexus
646
Subpubic ligament, 298
Subrostral fissure, 928
Subscapular angle, 173
artery, 653
bursa, 307
fascia, 473
fossa, 172
nerves, 1001
Subscapularis muscle, 473
Subserous areolar coat of lungs
1403
tissue, 1256
connective tissue, 1256
Substance of cord, gray, 855
white, 856
Substantia ferruginea, 880
nigra, 906, 907
propria of cornea, 1120
reticularis alba, 933
Substerno-mastoid glands, 785
Subsylvian ramus, 924
Subtemporal fissure, 932
gyre, 932
Subtendinous iliac bursa, 333
synovial bursa, 265
Suburethral gland, 1495
Sucking pad, 383
Suctorial pad, 383
Sudoriferous glands, 1200
Sulco-marginal tract of cord, 854
Sulcus intraparietal of Turner,
930
lachrymal, 113
lateralis mesencephali, 905
lunatus, 931
of Monro, 916
oculomotorius, 904
orbito-palpebral, inferior, 1147
superior, 1147
parolfactory anterior, 935
posterior, 935
sagittal, 73, 80
scleral, 1115
sigmoid, 86
spiralis externus, 1182
internus, 1182
terminalis of His, 568, 1097
tympanic, 1159
Sulcus tympanicus, 1161
Supercentral fissure, 927
Supercerebellar veins, 736
Supercerebral veins, 735
Superciliary ridge, 80
Superficial anterior thoracic
nerve, 1001
branches of cervical plexus
989
cardiac .plexus, 1090
cerebellar veins, 736
cerebral veins, 735
cervical artery, 644
fascia, 388
glands, 783
nerve, 990
region, muscles of, 388
circumflex iliac artery, 704
vein, 756
crural arch, 438, 1541
dorsal veins of penis, 762
epigastric artery, 704
external pudic artery, 704
fascia, 366
of abdomen, 434, 1523
of arm, 472
of back, 413
of cranial region, 368
of femoral region, 514
of perinaeum in male, 457
of shoulder, 472
of thoracic region, 465
femoral artery, 701
inguinal lymphatic glands, 791
long plantar ligament, 355
lymphatic glands of upper ex-
tremity, 787
vessels of gluteal region, 799
of lower extremity, 794
of penis, 799
of perinaeum, 799
of scrotum, 799
of upper extremity, 790
of walls of abdomen, 799
muscles of abdomen, 434
palmar arch, 666
parotid lymphatic glands, 779
perineal artery, 691
sural artery, 710
sylvian vein, 735
temporal artery, 612
nerves, 1052
vein, 727
transverse ligament of fingers,
496
veins of fingers, 745
of foot, 756
of hand, 745
of lower extremity, 756
of upper extremity, 745
ventro-lateral spino-cerebellar
tract, 852
Superficialis colli nerve, 990
volse artery, 661
Superfrontal fissure, 927
gyre, 928, 929, 930
Superior acromio-clavicular lig-
ament, 301
astragalo-scaphoid ligament,
356
branch of superior cervical
ganglion, 1083
calcaneo-cuboid ligament, 355
calcaneo-scaphoid ligament,
355
cardiac nerve, 1085
carotid triangle, 396
cerebellar artery, 642
cerebral veins, 735
cervical ganglion, 1081
constrictor muscle, 403
Superior coronary artery of lip,
609
dental plexus, 1048
epigastric artery, 647
glands, 800
fibular artery, 712
flexure of duodenum, 129a
gemellus muscle, 529
gluteal nerve, 1027
hsemorrhoidal artery, 680
plexus of nerves,' 1095
veins, 768
intercostal artery, 647
veins, 752
lachrymal gland, 1151
laryngeal artery, 605
nerve, 1071
ligament of incus, 1171
of malleus, 1170
lingualis muscle, 401
longitudinal fasciculus, 962
sinus, 78, 130, 736
maxillary bones, 105
nerve, 1046
region, muscles of, 379
meatus of nose, 101, 144
mediastinum, 1396
medullary velum, 901
mesenteric artery, 677
plexus of nerves, 1094
vein, 768
nuchal line, 72
obliquus oculi muscle, 376
olivary nucleus, 887
ophthalmic vein, 740
orbito-palpebral sulcus, 1147
petrosal sinus, 742
phrenic artery, 646
veins, 767
precentral fissure, 927
profunda artery, 657
pubic ligament, 298
pyloric artery, 675
radio-ulnar articulation, 316
ramus of ischium, 218
of pubis, 219
rectus oculi muscle, 375
sacro-sciatic foramen, 296
semicircular canal, 1175
stephanion, 76, 150
sterno-pericardiac ligament.
560
superficial cerebellar veins, 736
external pudic artery, 704
surface of liver, 1336
tarsal arch, 625
thoracic artery, 652
thyroid artery, 604
vein, 730
transverse ligament, 304
turbinated bone, 101
crest, 117
vena cava, 752. See Precava.
vesical artery, 687
plexus of veins, 761
vocal cords, 1378
Supernumerary bones, 103
spleens, 1363
Superpetrosal sinus, 742
Supertemporal fissure, 932
gyre, 932
Supinator longus muscle, 486
radii brevis muscle, 489
Supporting cells of Hensen, 1185
Supra-acromial artery, 644
nerves, 992
Supraclavicular glands, 785
nerves, 991
Supracommissure of Osborn, 915
Supracondylar ridge, external,.
181
1607
Supracondylar ridge, internal
181
Supracondyloid glands of Leaf
794
Supraepitrochlear glands, 787
Supraglenoid tubercle, 176
Suprahyoid aponeurosis, 396
artery, 606
glands, lateral, 784
median, 784
region, muscles of, 396
Supramandibular nerves, 1063
Supramarginal gyre, 931
Supramastoid crest, 84, 137
Supramaxillary lymphatic
glands, 781
nerves, 1063
Suprameatal spine, 88
triangle, 85
Supraorbital arch, 80
artery, 625
foramen, 80, 140.
nerve, 1044
notch, 80, 140
ridge, 140
vein, 726
Suprapatellar bursa, 342, 521
Suprarenal artery, 680
capsule, 1437
arteries of, 1440
left, 1438
lymphatic vessels of, 802
lymphatics of, 1440
nerves of, 1440
relations of, 1437
right, 1437
structure of, 1438
veins of, 1440
glands, 1437
accessory, 1438
impression of liver, 1337
plexus of nerves, 1092
veins, 767
Suprascapular artery, 643
ligament, 304
nerve, 1000
notch, 175
Suprascleral lymph-space, 1113
Supraspinales muscle, 423
Supraspinatus fascia, 474
muscle, 474
Supraspinous fossa, 174
ligament, 275
Suprasternal artery, 644
nerves, 991
notch, 411
space, 389
Supratonsillar fossa. 1223
Supratrochlear foramen, 183
glands, 787
nerve, 1044
Supravaginal portion of uterus,
1500
Surface form of abdominal aorta,
672
of acromio-clavicular artic-
ulation, 303
of ankle-joint, 353
of axillary artery, 651
of bladder, 1449
of bones, 34
of brachial artery, 656
of carotid arteries, common,
601
external. 603
of carpus, 206
of clavicle. 172
of common iliac arteries,
684
of dorsalis pcdis artery, 714
of elbow-joint, 314
Surface form of external auditory
meatus, 1160
iliac artery, 684, 696
of eyelids, 1152
of femoral artery, 702
of femur, 231
of fibula, 241
of fifth nerve, 1055
of foot, 257, 362
of heart, 580
of hip, 335
of humerus, 185
of hyoid bone, 156
of inferior radio-ulnar artic-
ulation, 319
of internal iliac artery, 695
of intestines, 1331
of kidney, 1434
of knee-joint, 345
of lachrymal gland, 1153
sac, 1153
of liver, 1353
of lungs, 1405
of metacarpo-phalangeal ar-
ticulation, 327
of mouth, 1229
of muscles of abdomen, 450
of back, 426
of face, 387
of head, 387
of lower extremity, 552
of upper extremity, 502
of vertebral region, 411
of pancreas, 1360
of parotid duct, 1225
of patella, 234
of pelvis, 222
of plantar arteries, 719
of popliteal artery, 709
of radial artery, 660
of radio-carpal articulation,
320
of radius, 194
of rectum, 1331
of scapula, 178
of shoulder-joint, 309
of skull, 148
of spleen, 1366
of sterno-clavicular articu-
lation, 301
of sterno-mastoid muscle,
393
of sternum, 166
of stomach, 1288
of subclavian artery, 637
of superior radio-ulnar ar-
ticulation, 316
of temporo-mandibular ar-
ticulations, 284
of tibial artery, anterior, 711
posterior, 716
of trachea, 1389
of trifacial nerve, 1055
of trigeminal nerve, 1055
of ulnar artery, 663
of vermiform appendix, 1331
of vertebral column, 69
Surgical anatomy of abdominal
aorta, 672
of abducent nerve, 1058
accessory nerve, 1074
of acromio-clavicular articu-
lation, 303
of ankle-joint, 353
of arch of aorta, 594
of artery of bulb, 692
of ascending pharyngeal ar-
tery, 612
of auditory nerve, 1065
of axilla, 647
of axillary artery, 651
Surgical anatomy of axillary
vein, 748
of azygos veins, 753
of bend of elbow, 655
of bile-duct, 1354
of bladder, 1449
of brachial artery, 656
plexus, 1009
of carotid arteries, common,
601
external, 603
internal, 623
gland, 1064
of carpus, 207
of cavernous sinus, 740
of cervical fascia, 391
ganglion, 1087
plexus, 994
of cheeks, 1234
of clavicle, 172
of colon, 1334
of common iliac arteries,
684
of conjunctiva, 1154
of deep epigastric artery,
698
of -descent of testicles, 1 472
of dorsalis pedis artery, 714
of duodenum, 1332
of ear, 1186
of eighth nerve, 1065
of elbow-joint, 314
of eleventh nerve, 1074
of emissary veins, 743
of external iliac artery, 696
of eye, 1144
of eyelashes, 1153
of eyelids, 1153
of facial artery, 610
nerve, 1064"
veins, 726
of fascia of femoral region,
anterior, 517
of femoral artery, 702
of femur, 232
of fibula, 244
of foot, 258, 362
of gall-bladder, 1354
of glosso-pharyngeal nerve,
1067
of gums, 1234
of hffimorrhoidal veins, 761
of heart, 580
of hernia, 1523
of hip, 335
of humerus, 185
of hyoid bone, 156
of hypoglossal nerve, 1077
of inferior calcaneo-scaphoid
ligament. 356
thyroid artery, 643
of innominate artery, 597
of intercostal artery, 670
nerves, 1014
of internal iliac artery, 687,
695
jugular vein, 732
mammary artery, 647
pudic artery in male, 691
of intestines, 1331
of ischio-rectal region, 1547
of kidney, 1434
of knee-joint, 345
of lachrymal gland, 1154
sac, 1154
of lateral sinus, 739
of ligaments of vertebra, 281
of lingual artery, 606
of lips, 1234
of liver, 1354
of lumbar plexus, 1034
H.OS
INDEX
Surgical anatomy of lungs, 1406
of lymphatic glands, 775
of lymphatics of mammary
'gland, 811
of neck, 786
of upper extremity, 791
vessels of peritoneum, 80(
of stomach, 804
of male breast, 1522
of mammary gland, 1520
of maxillary artery, exter-
nal, 610
of Meibomian glands, 1 153
of membranes of cord, 860
of middle meningeal artery,
615
of mouth, 1234
of muscles of acromial re-
gion, 473
of arm, 480
of femoral region, anterior,
521
internal, 525
posterior, 534
of gluteal region, 531
of iliac region, 513
of lateral thoracic r.egion,
471
of leg, 544
of lower extremity, 554
of orbital region, 377
of palatal region, 408
of radio-ulnar region, an-
terior, 486
posterior, 493
of tongue, 402
of upper extremity , 505
of nasal fossm, 1112
of ninth nerve, 1067
of occipito-frontalis muscle,
371
of oculomotor nerve, 1040
of oesophagus, 1240
of olfactory nerve, 1038
of optic nerve, 1038
of ovary, 1515
of palate, 1234
of palatine artery, 617
of palmar fascia, deep, 496
of pancreas, 1360
of parathyroid glands, 1413
of patella, 234 .
of pelvis, 222
of penis, 1470
of pericardium, 563
of perinseum, 1547
of peritoneum, 1274
of pharynx, 1234
of phrenic nerve, 993
of plantar arteries, 719
fascia, 546
of pleura, 1395
of popliteal artery, 709
of postcava, 766
of precava, 753
of pronator radii teres mus-
cle, 481
of prostate gland, 1462
of prostatico-vesical plexus,
762
of radial artery, 660
of radio-carpal articulation,
320
of radius, 194
of rectum, 1333
of salivary glands, 1234
of saphenous veins, 757
of scapula, 178
of scrotum, 1478
of seminal vesicles, 1487
of seventh nerve, 1064
Surgical anatomy of shoulder
joint, 309
of sixth nerve, 1058
of skull, 150
of spermatic cord, 1478
veins, 766
of spinal cord, 860
of spleen, 1366
of sterno-clavicular articula-
tion, 301
of sterno-mastoid muscle
393
of sternum, 167
of stomach, 1288
of subclavian artery, 637
of superficial fascia of cra-
nial region, 369
inguinal lymphatic glands
794
of superior radio-ulnar artic-
ulation, 316
of synovial tendons at wrist,
494
of tarsal joint, 358
of tarsus, 257
of temporal artery, 613
of temporo-mandibular ar-
ticulations, 284
of tenth nerve, 1072
of testicles, 1484
of thoracic aorta, 668
of thyroid artery, superior,
605
gland, 1411
of tibia, 244
of tibial artery, 716
anterior, 711
of tongue, 1103
of tonsils, 1234
of trachea, 1389
of triangles of neck, 618
of trochlear nerve, 1041
of twelfth nerve, 1077
of ulna, 194
of ulnar artery, 663
of ureter, 1437
of urethra, male, 1454
of utero-ovarian artery, 689
of uterus, 1508
of vagus nerve, 1072
of vermiform appendix,
1332
of vertebral artery, 641
column, 69
neck of humerus, 179
of scapula, 173
Suspensory ligament of axilla,
466
of clitoris, 439
of eye, 1115
of lens, 1139
of liver, 1340
of malleus, 1170
of mamma, 465
of ovary, 1513
of penis, 439
of Treitz, 1294
muscle of duodenum, 1294
Sustentacular cells of spleen, 1363
fibres, 1131
Sustentaculum lienis, 1268
tali, 257
Sutura, 266
dentata, 266
harmonia, 266
limbosa, 266
notha, 266
serrata, 266
squamosa, 266
vera, 266
Sutural bones, 103
Sutural ligament, 261
membrane, 266, 973
Suture or sutures, basilar, 128
coronal, 78, 127
cranial, 127
endo-exo-gnathion, 111
endo-gnathion, 111
endo-meso-gnathion, 111
ethmo-frontal, 130
ethmo-sphenoidal, 130
exo-gnathion, 111
frontal, 79, 127
fronto-malar, 128
fronto-parietal, 127
fronto-sphenoidal, 128, 130
intermaxillary, 139
internasal, 139
interparietal, 127
lambdoid, 75, 78, 128
masto-occipital, 75, 128
masto-parietal, 128
meso-exo-gnathion, 111
meso-gnathion, 111
metopic, 83, 127
naso-maxillary, 139
occipito-parietal, 128
petro-occipital, 75, 128, 133
petro-sphenoidal, 128, 136
petro-squamous, 88
sagittal, 78, 127
spheno-parietal, 128
squamo-parietal, 128
squamo-sphenoidal, 128
squamous, 85, 128
transverse, 128
facial, 128
Sweat-glands, 1200
Sylvian cleft, development of, 925
fissure, 924
vein, superficial, 735
Symington, ano-coccygeal body
' of, 1324
Sympathetic nerve, 827
ganglion of, 1067
plexuses of, 1090
structure of, 1079
Symphysis, 266, 269
' of jaw, 122
sacro-coccygeal, 66
Synarthrosis, 266
Synchondrosis, 266
Syndesmo-odontoid joint, 276
Syndesmosis, 267
Synovial bursa, 265
thecal, 265
ligaments, 264
membranes, 264
articular, 264
bursal, 265
of flexor tendon at wrist,
494
surgical anatomy of,
494
vaginal, 265. See also Indi-
vidual joints,
sheaths, 265
villi, 264
Systemic arteries, 585
veins, 724
TABLES of skull, 33
Tabular portion of occipital bone,
71
Tactile corpuscle, 826, 830
Tsenia pontis, 906
semicircularis, 913, 943, 954
thalami, 912
Talipes, 541
Tapetum of callosum, 945
Tapetum of choroid, 1124
lucidum, 1137
nigrum, 1137
Tarsal arch, 625
artery, 714
bones, development of, 255
glands, 1149
joint, surgical anatomy of,
358
ligament, external, 372
internal, 372
plates of eyelid, 1149
Tarso-metatarsal articulations,
359
Tarsus, 244
articulations of, 354
surface form of, 257
surgical anatomy of, 257
synovial membrane of, 354
Taste-buds, 1100
Teeth, 1205
arrangement of, 1208
auditory, 1183
bicuspid, 1208
•canine, 1207
«ementum of, 1214
cortical substance of, 1214
deciduous, 1206
•development of, 1214
•enamel of, 1213
eruption of, 1218
eye, 1207
general characters of, 1205
grinders, 1208
incisors, 1207
Ivory of, 1212
milk, 1206
molar. 1208
permanent, 1206
superadded, 1218
premolars, 1208
roots of, 1206
solid portion of, 1211
stomach, 1207
structure of, 1210
surfaces of, 1205
temporary, 1206
Tegmen tympani, 87
Tegmental tract, central, 910
Tegmentum, hypothalamic sub-
stance of, 915
of mid-brain, 908
nucleus of, 908
Tela chorioidea inferior, 981
superior, 981
subcutanea, 1190
Telancephalon, 911
Telodendria, 823, 828
Temporal artery, 613
anterior, 613, 642
from internal maxillary, 615
middle, 613
posterior, 613, 642
surgical anatomy of, 613
bone, 83
articulations of, 92
. attachment of muscles to,
92
development of, 91
mastoid portion of, 85
petrous portion of, 88, 136
• squamous portion of, 83
crest, 76, 80, 84
diploic vein, 734
fascia, 384
fossa, 76, 137
lines, 76, 80
lobe, 931
fissures of, 931
gyre of, 932
muscle, 384
INDEX
Temporal nerves from auriculo-
temporal, 1052
deep, 1051
from facial, 1046, 1062
ridges, 76, 80
veins, 727
Temporary teeth, 1206
eruption of, 1219
Temporo-facial nerve, 1062
Temporo-malar filaments, 115
foramen, 115
nerve, 1046
Temporo-mandibular articula-
tions, 282
surface form of, 284
surgical anatomy of, 284
region, muscles of, 383
Temporo-maxillary articulation,
138
vein, 727
Temporo-pontile tract, 910, 957
Tendo Achillis, 538
bursa of, 538
oculi, 372
Tendons, 366
of diaphragm, central, 431
cordiform, 431
flexor, fibrous sheaths of, 548
Tenon, capsule of, 113
Tensor fascia! femoris muscle, 517
palati muscle, 406
tarsi muscle, 373
tympani muscle, 1171
canal for, 1163
Tenth nerve, 1068
surgical anatomy of, 1072
thoracic vertebra, 56
Tentorial sinus, 738
Tentorium, 975
Teres major muscle, 475
minor muscle, 475
Terma, 867, 917
Terminal arteries, 632
Testes gubernaculum, 1471
muliebres of Galen, 1511
of quadrigemina, 705
Testicles, 1471
coverings of, 1472
descent of, 1471
gubernaculum testis, 1471
lobes of, 1482
lymphatic vessels of, 802
mediastinum testis, 1481
. parenchyma of, 1482
rete testis, 1482
sheaths of, proper, 1481
size of, 1481
structure of, 1482
surgical anatomy of, 1484
trabeculaj of , 1482
tubuli seminiferi of, 1482
tunica albuginea, 1482
vaginalis, 1481
vasculosa, 1482
tunics of, 1481
weight of, 1481
Testicular bag. 1472
Thalamencephalon, 911
Thalami, 867, 912
Thalamo-cortical fibres, 914
Thalamo-frontal fibres, 956
Tlialamo-olivary tract, 886
Thalamo-striate fibres, 956
Thalamus, 912
connections of, 914
fibres of, 914
structure of, internal, 914
Thalamic radiation, 914
Thebesian valve, 569, 771
Thecal synovial bursa, 265
Thigh, bones of, 223
1609
Thigh, fascia of, 514
muscles of, 514
Third nerve, 1039
ventricle of brain, 869, 916
Thoracic aorta, 667
branches of, 668
surgical anatomy of, 668
aortic plexus, 1087
artery, acromial, 653
alar, 653
long, 653
superior, 652
axis, 653
cardiac nerves, 1072
duct, 775
structure of, 777
ganglion, 1087
nerves, 1010
branches of, 1010
divisions of, 1010
roots of, 1010
portion of gangliated cord,
1087
of oesophagus, 1236
region, anterior, fascia of, deep,
465
superficial, 465
muscles of, 465
lateral, muscles of, 471
surgical anatomy of, 471
surface of lungs, 1400
trachea, lymphatic vessels of,
813
vein, long, 748
vertebra?, 53
bodies of, 53
eleventh, 56
first, 55
laminae of, 54
ninth, 55
peculiar, 55
pedicles of, 54
processes of, 54
tenth, 56
twelfth, 56
wall, lymphatic glands of, 807
vessels of, 810
Thoracico-epigastric vein, 748
Thoracico-lumbar nerve, 1014
Thorax, 156
boundaries of , 156
cavity of, 558
fascise of, 426
lymphatics of, 807
muscles of, 426
nerves of, cutaneous, 1012
openings of, lower, 558
upper, 558
veins of, 744
Thumb, ligaments of, 323
metacarpal bone of, 203
muscles of, 486
Thymic artery, 596
lymphatic vessels, 813
Thymus gland, 1414
arteries of, 1415
lobes of, 1414
Ivmphatics of, 1415
nerves of, 1415
structure of, 1414
veins of, 1415
Thyro-arytenoid ligament, infe-
rior, 1378
superior, 1378
muscle, 1381
Thyro-epiglottic ligament, 1375
Thyro-epiglottideus muscle, 1381
Thyro-glossal duct, 1100, 1407
Thyro-hyals of hyoid bone, 155
Thyro-hyoid ligaments, 1374
membrane, 1374
1610
INDEX
Thyro-hyoid muscle, 395
nerve, 1077
Thyroid artery, inferior, 643
surgical anatomy of, 643
superior, 604
surgical anatomy of, 605
axis, 642
body, 1401
venous plexus on, 751
cartilage, 1370
foramen, 220
ganglion, 1085
gland, 1407
accessory, 1409
arteries of, 605, 1410
color of, 1407
isthmus of, 1409
lobes of, 1408
lymphatic vessels of, 782
lymphatics of, 1411
nerves of, 1411
structure of, 1409
surgical anatomy of, 1411
veins of, 731, 1411
weight of, 1407
nerve, 1086
notch, 1370
veins, accessory, 731
inferior, 751
middle, 730
superior, 730
Thyroidea ima artery, 596
vein, 751
Tibia, 234
articulations of, 238
attachment of muscles to, 238
crest of, 237
development of, 238
lower extremity of, 238
surfaces of, 238
nutrient artery of, 7i8
oblique line of, 237
shaft of, 237
surfaces of, 237
spinous process of, 236
structure of, 238
surface form of, 239
tubercle of, 236
tuberosities of, 236
upper extremity of, 236
Tibial artery, anterior, 710
branches of, 712
peculiarities of, 711
relations of, 711
surface marking of, 711
surgical anatomy of, 711
posterior, 715
branches of, 716
peculiarities of, 716
relations of, 715
surface marking of, 716
surgical anatomy of, 716
recurrent, anterior, 713
posterior, 712
bursa, subcutaneous, 342
gland, anterior, 794
nerve, 1030
branches of, 1031, 1033
veins, anterior, 758
posterior, 758
Tibialis anticus muscle, 535
bursa of, 535
posticus muscle, 541
Tibio-fibular articulation, 347
region, anterior, muscles of, 534
posterior, muscles of, 537
Tibio-tarsal ligament, anterior,
349
posterior, 349
Tissue, adipose, pads of, 265
areolar, subserous, 1256
Tissue, connective, subserous
1256
elastic, yellow, 264
fibrous, white, 263
intertubular, 1213
subarachnoid , 859
Tomes' fibres, 1213
granular sheath of, 1212
Tongue, 1097
anterior portion of, 1097
apex or tip of, 1 097
arteries of, 1102
base or root of, 1097
body of, 1097
cerium of, 1099
development of, 1253
dorsum of, 1097
fibrous septum of, 400
fraenum of, 1097
glands of, 1101
lymphatic vessels of, 782
lymphatics of, 1103
margin of, 1097
mucous membrane of, 1098
muscles of, 400, 1102
extrinsic, 400
intrinsic, 400
surgical anatomy of, 402
nerves of, 1103
oral portion of, 1097
papillae of, 1099
pharyngeal portion of, 1097
posterior portion of, ] 097
raph^of, 1097
structure of, 1098
surface of, 1 097
surgical anatomy of, 1103
veins of, 1102
Tongue-like lobe of liver, 1343
Tonsil, 1223
arteries of, 1223
development of, 1253
lingual, 1098
lymphatics of, 1223
nerves of, 1223
pharyngeal, 1231, 1234
surgical anatornv of, 1234
veins of, 1223
Tonsillar artery, 608
nerves, 1067
Tooth germ, 1216
Torcular, 74, 737
Touch-corpuscles of Meissner
and Wagner, 830
Trabeculse corpus cavernosum,
1468
of spleen, 1363
of testicle, 1482
Trachea, 1384
arteries of, 643, 1388
cartilages of, 1386 v
fibrous membrane of, 1387
lymphatics of, 1389
mucous membrane of, 1388
muscular fibres of, 1386
nerves of, 1388
relations of, 1384
structure of, 1386
surface form of, 1389
surgical anatomy of, 1389
thoracic, Ivmphatic vessels of,
813
veins of, 751, 1388
Tracheal arteries, 643
glands, 786, 1388
veins, 751
Trachelo-mastoid . muscle, 421
Tract cells of cord, 855
of cord, cerebello-spinal, 853
conducting, 841
direct cerebellar, 852
Tract of cord, dorso-lateral spino-
cerebellar, 852
functions of, 844
intermedio-lateral, 853
lateral vestibulo-spinal, 853.
marginal, 851
olivo-spinal, 853
prepyramidal, 853
pyramidal crossed, 853
direct, 854
rubro-spinal, 853
spino-mesencephalic, 852.
spino-olivary, 853
spino-thalamic, 852
sulco-marginal, 854
superficial ventro-lateral
spino-cerebellar, 852
ventral cerebello-spinal, 854'
vestibulo-spinal, 854
fronto-pontile, 910
geniculate, 956
of Cowers, 901
marginal of Spitzka and Lis—
sauer, 852
motor, 956
occipito-pontile, 956, 957
olfactory, 867, 934, 935, 1037
optic, 1038
central connections of, 917
pyramidal, 956
of crusta, 910
spino-cerebellar, ventral, 901
spino-olivary, 886
tegmental, 910
temporo-pontile, 910, 957
thalamo-olivary, 886
Tractus cerebello-tegmentalis,
901
peduncularis transversus, 906
rubrospinalis, 908, 909
spino-tectalis et thalamicus.,
853
spiralis foraminosus, 89
Tragicus muscle, 1157
Tragus, 1155
Transinsular fissure, 933
Transitional epithelium, 1437
Transorbital fissure, 929
Transparietal fissure, 931
Transprecentral fissure, 928
Transtemporal fissure, 932
gyre, 932
gray substance of, 960
Transversalis cervicis muscle, 421
colli artery, 644
muscle, 421
fascia, 447, 1529
humeri artery, 643
muscle, 444, 1528
Transverse cervical artery, 644
colon, 1317
flexure of, splenic, 1317
diameter of pelvis, 210
facial artery, 613
suture, 128
vein, 727
fibres of pons, 887
foramen, 50
humeral ligament, 307
ligament of acetabulum, 332
of atlas, 277
inferior, 304
of knee, 342
superior, 304
lingualis muscle, 401
mesocolon, 1268, 1317
metacarpal ligament, 326
pelvic ligament, 461
perineal artery, 692
ligament, 461
processes of a vertebra, 49>
1XDEX
1611
Transverse sinus, 743
of pericardium, 562
suture, 128
Transversus auricula* muscle,
1157
menti muscle, 380
perinei superficialis muscle,
459, 462
Trapezium, 887
bone, 200
articulations of, 200
attachment of muscles to,
200
surfaces of, 200
Trapezius muscles, 413
Trapezoid bone, 200
articulations of, 201
surfaces of, 200
ligament, 302
ridge, 169
TreiU, fossa of, 1270
suspensory ligament of, 1294
Triangle, carotid, inferior, 618
superior, 396, 619
of elbow, 655
of election, 619
Hesselbach's, 1532
of necessity, 618
of neck, anterior, 618
posterior, 620
surgical anatomy of, 618
occipital, 620
Petit's, 437
Scarpa's, 518, 698
subclavian, 620
submaxillary, 396, 619
suboccipital, 425
suprameatal, 85
Triangular cartilage of septum of
nos«, 1107
fascia of abdomen, 439, 1527
of urethra, 460
interarticular fibro-cartilage,
317
ligament of urethra, 460
muscles, 365
Triangularis menti muscle, 380
sterni muscle, 427
Triceps extensor cubiti muscle,
479
Tricuspid orifice, 569
valve, 572
Trifacial nerve, 1041
surface marking of, 1055
surgical anatomy of, 1055
Trigeminal depression, 88
nerve, 1041
distribution and connections
of, 1055
nuclei of, 894
afferent, 894
efferent, 894
surface marking of, 1055
surgical anatomy of, 1055
Trigone of bladder, 1447
Trigonum habemi-, 912, 915
hypoglossi, 880
lemnisci, 905
olfactorium, 935
vagi, 880
vrntriculi, 944
vesicse, 1447
Trigoid bodies, 822
Trochanter, great, 225
bursa of, 333
lesser, 225
rudimental, third, 226
Trochanteric fossa, 225
Trochlea of femur, 227
of humerus, 183
Trochlear fossa. 82
Trochlear nerve, 1041
nucleus, 910
surgical anatomy of, 1041
surface of astragalus, 246
Trochoid, 267
Trolard, anastomotic vein of, 735
Troltsch, recessus of, 1172
True vocal cords, 1378
Trunk, arteries of, 667
articulations of, 271
fascia* of, 412
muscles of, 412
of vagus nerve, ganglion of,
1069
Tube or tubes, bronchial, 1384
egg, 1515
Eustachian, 1163
Fallopian, 1510
lymphatic vessels of, 801
neural, 817
spiral, of Schachowa, 1427
tonsil, 1165
Tuber, 867, 917
cinereum, 917
Tuberal lobe of ferebellum, 898
Tubercle, adductor, 227
amygdaloid, 945
carotid, 51
of cervical vertebra, anterior,
50
posterior, 50
Chassaignac's, 69
conoid, 169
comical, of Santorini, 1376
cuneate, 876
cuneiform, of Wrisberg, 1376
of Darwin, 1155'
deltoid, 169
of epiglottis, 1373
of femur, 225
genial, 123
of hyoid bone, 155
infraglenoid, 176
jugular, 74
lachrymal, 109
mental, 122
of navicular bone, 249
olfactory, 935
peroneal, 246
pharyngeal, 73
pterygoid, 97
of quadratus, 226
of ribs, 162
^of scaphoid, 198
supraglenoid, 176
of tibia, 236
of ulna, 188
of zygoma, 84
Tuberculum acusticum, 880
anterius, 913
caudatum, 1340
cinereum, 876, 884
impar, 1253
vestibularis, 880
Tuberosity, bicipital, 192
of calcaneus, 246
of cuboid, 248
of femur, inner, 228
outer, 228
of humerus, 179
of ischium, 218
maxillary, 106
of navicular bone, 249
of palate bone, 117, 135
of radius, 192
of ribs, 162
of sacrum, 63
of scaphoid bone, 249
of tibia external, 236
internal, 236
Tubuli, lactiferi, 1519
Tubuli seminiferi, 1482
uriniferi, 1427
Tunic of Ruysch, 1123
Tunica adventitia, 1238
albuginea, 376, 1467, 1482
interna, 1130
propria, 1190
vaginalis, 1472, 1475, 1481
cavity of, 1481
parietal portion of, 1481
visceral portion of, 1481
vasculosa testis, 1482
Tunics of eye, 1117
of testicle, 1481
Turbinated bone, inferior, 119
articulations of, 120
development of, 120
surfaces of, 120
middle, 101
sphenoidal, 143
superior, 101
crest, 107, 117
Tiirck, bundle of, 910. Note.
fasciculus of, 854
Turner, intraparietal sulcus of,
930
Twelfth nerve, 1074
surgical anatomy of, 1077
thoracic vertebra, 56
Tympanic antrum, 87
aperture, 1161
artery from ascending pharyn-
geal, 612
from internal carotid, 623
maxillary, 615
attic, 87
cavity, 1160
nerve, 1067
from facial, 1061
plexus of, 1067
sulcus, 1159
Tympanohyal process, 92
Tympanomalleolar ligaments,
1166
Tympanum, 1160
arteries of, 1172
cavity of, 1160
floor of, 1161
fundus of, 1161
mucous membrane of, 1172
muscles of, 1171
nerves of, 1173
ossicles of, 1168
pyramid of, 1163
roof of, 1161
veins of, 1173
walls of, 1163
ULNA, 186
articulations of, 191
attachment of muscles to, 191
development of, 191
lower extremity of, 191
shaft of, 190
structure of, 191
surface form of, 191
surgical anatomy of, 194
tubercle of, 188
upper extremity of, 186
coronoid process of, 186
olecranon process of, 186
sigmoid cavities of, 188
Ulnar artery, 662
peculiarities of, 663
surface marking of, 663
surgical anatomy of, 663
groove, 183
nerve, 1005
1612
INDEX
Ulnar region, muscles of, 500
veins, 745
Umbilical arteries in foetus, 583
686
fissure of liver, 1338
fossa of liver, 1338
notch, 1338
region, contents of, 1244
Umbilicus, lymphatic vessels of,
799
Umbo, 1167
Unciform bone, 201
articulations of, 201
attachment of muscles to,
201
process of ethmoid, 100
Uiicinate fasciculus, 962
gyre, 932
process of Winslow, 1357
Uncus, 932, 937
Ungual phalanges, 206
Unipolar cells, 820
Unstriated muscle, 363
Unstriped muscle, 363
Upper deep cervical glands, 785
extremity, arteries of, 633
articulations of, 299
bones of, 169
fasciae of, 464
lymphatic glands of, 787
vessels of, 790
muscles of, 464
surface form of, 502
veins of, 744
subscapular nerve, 1001
Urachus, 1445
fold of, 1531
Ureter, 1435
arteries of, 1437
fibrous coat of, 1436
lymphatic vessels of, 802
mucous coat of, 1436
muscular coat of, 1436
nerves of, 1436
orifices of, 1447
relations of, 1435
structure of, 1435
surgical anatomy of, 1437
Ureteral folds, 1448
Urethra, female, 1455
lymphatic vessels of, 801
mucous coat of, 1456
muscular coat of, 1455
orifice of, 1493
structure of, 1455
submucous coat of, 1456
male, 1450
bulb of, 1468
cavernous portion of, 1452
crest of, 1451
fossa navicularis of, 1453
lymphatic vessels of, 801
membranous portion of,
1451
mucous coat of, 1453
muscular layer of, 1454
portion of, 1451
pendulous portion of, 1452
penile portion of, 1452
prostatic portion of, 1450
spongy portion of, 1452
structure of, 1453
submucous tissue of, 1454
surgical anatomy of, 1454
Urinary bladder. See Bladder.
organs, 1419
Uterine artery, 688
portion of Fallopian tube
1510
plexus of nerves, 1096
veins, 763
Uterine veins, plexus of, 763
Utero-sacral ligaments, 1502
Utero-vaginal plexu.s, 1095
Utero-vesical fold, 1502
pouch, 1499, 1502
Uterus, 1498
abnormalities of, 1505
appendages of, 1509
arbor vitse of, 1505
arteries of, 1507
bicornate, 1505
body of, 1499
cavity of, 1503
changes induced by pregnancy
1505
at menstrual period, 1505
at different ages, 1505
folds of, 1501
fundus of, 1499
ganglia of, 1096
ligaments of, 1501
lymphatic vessels of, 801, 150£
masculinus, 1451
mucous membrane of, 1504
muscular coat of, 1504
neck of, 1500
nerves of, 1096, 1508
after parturition, 1507
structure of, 1503
supravaginal portion of, 1500
surgical anatomy of, 1508
vaginal portion of, 1500
veins of, 1508
Utricle of vestibule, 1179
Uvea, 1128
Uvula of throat, 1221
vesicse, 1447
Uvular lobe of cerebellum, 898
VAGAL, accessory portion of
accessory nerve, 1073
Vagina, 1495
arteries of, 1497
azygos arteries of, 688
columns of, 1496
erectile tissue of, 1497
lymphatic vessels of, 802, 1 49
mucosa intertubercularis, 306
membrane of, 1496
muscular coat of, 1496
nerves of, 1497
orifice of, 1493
relations of, 1496
rugse of, 1496
structure of, 1496
veins of, 1497
vestibule of, 1493
Vaginal artery, 688
bulb, 1495
fornix, 1496
plexus of nerves, 1096
portion of uterus, 1 500
process of temporal bone, 90
synovial membrane, 265
veins, 763
plexuses of, 763
Vagus nerve, ganglion of root
of, 1069
of trunk of, 1069
nuclei of, 890
afferent, 890
efferent, 891
surgical anatomy of, 1072
Valentin, ganglion of, 1047
Vallecula, 895
epiglottica, 1373
sylvii,924
Vallev of cerebellum, 890, 891
Valsalva, sinuses of, aortic, 575
pulmonary, 573
Valve or valves, anal, 1326
of Bauhin, 1315
bicuspid, 574
coronary, 569
Eustachian, 569
in foetus, 581
of Gerlach, 1301
of Guerin, 1453
of Hasner, 1152
Houston's, 1326
ileo-CEecal, 1315
of Kerkring, 1299
of Morgagni, 1326
pyloric, 1280
rectal, 1326
semilunar, 1326
aortic, 574
pulmonic, 573
Thebesian, 569, 771
tricuspid, 572
Valvula, 879, 895, 901
Valvulze conniventes, 1299
Vas deferens, 1482
artery of, 687
lymphatic vessels of, 802
structure of, 1483
spirale, 1183
Vasa brevia arteries, 676
intestini tenuis artery, 677
vasorum of arteries, 588
Vascular papillae, 1191
system at birth, changes in,
584
in foetus, 581
Vasomotor fibres, 826
nerves, 1081
Vastus externus muscle, 520
internus muscle, 520
Vater, ampulla of, 1352
corpuscles of, 830
Vegetative muscle, 363
Veins, 721
of abdomen, 755
anastomotic, of Troland, 735
angular, 726
appendicular, 768
of arm, 744
auditory, 1186
auricular, 727
axillary, 747
azvgos, 752
larger, 752
left lower, 753
upper, 753
right, 752
smaller, 753
basilar, 735
basilic, 746
median, 746
of bones, 41
brachial, 747
brachio-cephalic, 750
bronchial, 753
buccal, 726
cardiac, 770
cava, inferior, 764
superior, 752
cephalic, 747
median, 746
cerebellar, 736
cerebral, 734
cervical, anterior, deep, 733
posterior, deep, 733
choroid, 735
circumflex, iliac, 759
superficial, 756
companion, 747
coronary, 768
costo-axillary, 748
INDEX
1613
Veins, cystic, 7ti!>
digital, hand, 745
of diploe, 733
dorsal, of penis, 762
dorsi-spinal, 7V!
dorso-meilian, 736
of dura of brain. 974 g
dural, 730, 7*1
emissary, 743
emulgent, 766
epigastric, deep, 759
superficial, 756
of face, exterior of, 725
facial, 726
femoral, 758
of fingers, superficial, 745
of foot, 758
frontal, 725
of Galen, 735
gastric, 768
gluteal, 761
ha-morrhoidal, external, 760
inferior, 760
middle, 760
superior, 768
of hand, superficial, 745
of head, 724
of heart, 580
hepatic, 767
histology of, 722
hvpogastric, 760
iliac, circumflex, deep, 759
common, 764
external, 759
internal, 760
ilio-lumbar, 7(>4
innominate, 750
intercostal, 752
interosseous, of forearm, 747
intervertebral, 755
intralobular, 767
jugular, 728
laryngeal, inferior, 751
lingual, 729
longitudinal, inferior, 738
of lower extremity, 755
lumbar, 765
ascending, 753, 765
right, 752
mammary, internal, 750
masseteric, 727
maxillary, internal, 727
median, 745
anterior, 736
posterior, 736
medicerebral, 735
medidural, 734
medulli-spinal, 755
meningeal, 730, 734
meningo-rachulian, 754
mesenteric, 768
of muscle, 364
naso-frontal, 740
of neck, 724
of oblongata, 736
obturator, 761
occipital, 727
oeaophageai, 751
ophthalmic, 740
orbital. 727
ovarian, 766
palatine, 727
palmar, deep, 747
pancreatic, 768
of pelvis, 755
pharyngeal, 730
phrenic, 767
of pia of brain, 982
plantar, 758
plcstis of, palmar, 745
paropinniform, 765
Veins, plexus of, pharyngeal, 730
prostatic, 761
prostatico-vesical, 761
pterygoid, 727
spermatic, 765
spinal, 753 '
on thyroid body, 751
uterine, 763
vaginal, 763
vesical, inferior, 763
superior, 761
popliteal, 758
portal, 769
system of, 768
postcava, 764
precava, 752
profunda femoris, 759
pterygoid plexus, 727
pudic, 760
pulmonary, 723
pyloric, 768
radial, 745
deep, 747
ranine, 729
renal, 767
sacral, lateral, 760
middle, 764
saphenous, 756
sciatic, 761
spermatic, 765
spinal, 753
splenic, 768
subcerebellar, 736
subcerebral, 735
subclavian, 749
sublobular, 767
submaxillary, 727
supercerebellar, 736
supercerebral, 735
supraorbital, 726
suprarenal, 767
sylvian, superficial, 735
systemic, 724
temporal, 727
temporo-maxillary, 727
thoracic, long, 748
thoracico-epigastric, 748
of thorax, 744
thyroid, accessory, 731
gland, 731
inferior, 751
middle, 730
superior, 730
thyroidea ima, 751
tibial, 758
tracheal, 751
ulnar, 745
of upper extremity, 744
uterine, 763
vaginal, 763
velar, 735
ventricular, 735
ventro-median, 736
vennian, 735
of vertebrae, bodies of, 755
vertebral, 732, 751
Vidian, 730
Vela, medullary, 901
Velar veins, 735
Velum, 881, 895, 902, 946, 981
interpositum, 912, 946
medullary, 901
anterior, 901
inferior, 901
posterior, 901
superior, 901
pendulum, palati, 1221
Vena azygos major, 752
minor, 753
basis vertebra?, 49, 755
cava, ascending, 764
Vena cava, inferior, 764. See
Postcava.
superior, 752. See Precava.
magna Galeni, 735
Vena? basis vertebrarum, 755
comites, 723, 747
corporis striati, 735
interlobulares of kidney, 1432
Thebesii, 771
vorticosse, 1123
Venesection, 746
Venous arch, nasal, 725
plexus, intraspinal, 732
on thyroid body, 751
Venter ilii, 216
of scapula, 172
Ventral cerebello-spinal tract of
cord, 854
column of spinal cord, 840
crusta, 905
fissure of oblongata, 874
horn-cells of cord, 856
of cornua, 844
lamina of brain, 870
root of spinal cord, 836
nerve, 982 •
spinal artery, 640
spino-cerebellar tract, 901
vestibulo-spinal tract of cord,
854
white commissure of cord, 854
Ventricle of brain, fifth, 920, 921 ,
941
fourth, 878
lateral, 941
third, 869, 916
infundibular recess of, 917
Verga's 951
of heart, fibres of, 577
left, chordae tendinese of, 575
columnar carnea; of, 575
right, 571
chordae tendineae of, 572
columnar carneae of, 572
of larynx, 1379
Ventricular portion of heart, 570
veins, 735
Ventro-lateral fissure, 875
Ventro-median fissure, 874
Ventro-paramedian fissure of
spinal cord, 839
vein, 736
Verga's ventricle, 951
Vermian vein, 735
Vermiform appendix, 1311
arteries of, 1313
canal of, 1312
lymphatics of, 1314
mesentery of, 1269
mucous membrane of. 1313
muscular coat of, 1312
' serous coat of, 1312
structure of, 1312
subjnucous coat of, 1313
surface form of, 1331
surgical anatomy of, 1332
veins of, 1313
Vermis, 895
Verrucas gyri hippocampi, 933
Vertebras, 48
bodies of, veins of, 755
centrum of, 48
cervical, 49
seventh, 53
coccygeal, 61
development of, 58
dorsal, 53
false, 61
general characters of, 48
immovable, 61
ligaments of, 272
DR. M. LEWIS h MER:
1614 INDEX
Vertebrae, lumbar, 56
fifth, 57
process of, articular, 49
spinous, 49
transverse, 49
prominens, 53
sacral, 61
structure of, 58
thoracic, 53
peculiar, 55
Vertebral aponeurosis, 413, 418
artery, 639
surgical anatomy of, 641
border of scapula, 176
canal 49
column, 48
articulations of, 271
surface form of, 69
surgical anatomy of, 69
foramen, 49
groove, 156
ligaments, 272
plexus of nerves, 1086
region, muscles of, anterior,
408, 411
lateral, 410
ribs, 161
vein, 732, 751
Vertebrarterial foramen, 50
Vertebro-chondral ribs, 161
Vertebro-pericardial ligaments.
560
Vertebro-pleural ligament, 139C
Vertebro-sternal 'ribs,' 101
Vertex of skull, 129, 150
Vertical lingualis muscle, 401
plate of palate bone, 117
Verumontanum, 1451
Vesical arteries, 687, 688
plexus of nerves, 1095
of veins, inferior, 762
superior, 761
trigone, 1447
Vesicle, prostatic, 1451
Vesicles of brain, 864
optic, 865
Graafian, 1514
seminal, 1486
Vesico-uterine ligament, 1502
Vesicula prostatica, 1450
Vestibular artery, 1186
ganglion, 1065
nerve, 1065
branches of, 1065
nuclei of, 893
window, 1162
Vestibule, aortic, of Sibson,
574
of ear, 1174
of mouth, 1204
of nose, 1109
Vestibule of vagina, 1491
Vestibulo-spinal tract, of cord,
lateral, 853
ventral, 854
Vestigial fold of pericardium, 563
Vibrissse, 1106
Vicq d'Azyr, band of, 939
bundle of, 914, 916
Vidian artery, 617
canal, 96, 135
nerve, 1049
veins, 730
Vieussens, ansa of, 1086
Villi of small intestine, 1300
synovial, 264
Viscera, development of, 1245
Visceral cranium, 71
layer of pleura, 1391
lymphatics, 808
peritoneum, 1257
portion of tunica vaginalis,
1481
surface of liver, 1336
of stomach, 1278
Visual axis, 1116
purple, 1130
Vitreous body, 1139
humor of eye, 1139
table of skull, 34
Vocal cords, false, 1378
true, 1378
process, 1373 >
Voice, organs of, 1369
Volar interosseous nerve, 1004
Volkmann's canals, 38
Voluntary muscle, 363
Vomer, 120
alse of, 121, 143
articulations of, 122
development of, 122
surfaces of, 121
Vomerine cartilage, 1107
Vortex of heart, 578
\Vilvo-vaginal gland, 1495
W
WALDEYER, germinal epithelium
of, 1513
odontoblasts of, 1211
Wedge bones, 249
Wharton's duct, 1226
White commissure of cord, 854
fibrous tissue, 263
line of Hilton, 1327
substance of cord, 848, 856
W ilder, post-oblongata of, 874
Willis, circle of, 631, 642
Winslow, accessory anterior cru-
ral nerve of, 1020
Winslow, ligament of, posterior,
337
uncinate process of, 1357
Wirsung, canal of, 1359
Wornb, 1498
Worm of cerebellum, 895
Wormian bones, 103
development of, 104
Wrisberg, cardiac ganglion of.
1090
cartilages of, 1373
cuneiform tubercle of, 1376
ligament of, 341
nerve of, 1003
pars intermedia of, 1059
Wrist, articulations of, 319
bursa of, 494
Wrist-joint, 319
ligament of, 320
surface form of, 320
surgical anatomy of, 320
XIPHO-PERICARDIAL ligament,
561
Xiphoid appendix, 159
surfaces of, 159
cartilage, 157
Y-LJGAMENT, 330
Yellow elastic tissue, 264
spot of Sommerring, 1131
Z
ZINN, ligament of, 375
zonule of, 1139
Zona arcuata, 1183
fasciculata, 1439
glomerulosa, 1439
orbicularis, 329
pectinata, 1183
reticularis, 1439
tecta, 1183
Zones of brain, longitudinal, 870
Zonula ciliaris, 1139
Zonule of Zinn, 1139
Zygoma, 84
Zygomatic arch, 138
'fossa, 138
lymphatic glands, 781
process of malar, 115
of temporal bone, 84
Zygomaticus major muscle, 379
minor muscle, 379
Zymogen granules, 1352
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